stream-tcp.c

Go to the documentation of this file.

/* Copyright (C) 2007-2023 Open Information Security Foundation
 *
 * You can copy, redistribute or modify this Program under the terms of
 * the GNU General Public License version 2 as published by the Free
 * Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 */
 
/**
 * \file
 *
 * \author Victor Julien <victor@inliniac.net>
 * \author Gurvinder Singh <gurvindersinghdahiya@gmail.com>
 *
 * TCP stream tracking and reassembly engine.
 *
 * \todo - 4WHS: what if after the 2nd SYN we turn out to be normal 3WHS anyway?
 */
 
#include "suricata-common.h"
#include "suricata.h"
#include "packet.h"
#include "decode.h"
#include "detect.h"
 
#include "flow.h"
#include "flow-util.h"
 
#include "conf.h"
#include "conf-yaml-loader.h"
 
#include "threads.h"
#include "threadvars.h"
#include "tm-threads.h"
 
#include "util-pool.h"
#include "util-pool-thread.h"
#include "util-checksum.h"
#include "util-unittest.h"
#include "util-print.h"
#include "util-debug.h"
#include "util-device.h"
 
#include "stream-tcp-private.h"
#include "stream-tcp.h"
#include "stream-tcp-cache.h"
#include "stream-tcp-inline.h"
#include "stream-tcp-reassemble.h"
#include "stream-tcp-sack.h"
#include "stream-tcp-util.h"
#include "stream.h"
 
#include "pkt-var.h"
#include "host.h"
 
#include "app-layer.h"
#include "app-layer-parser.h"
#include "app-layer-protos.h"
#include "app-layer-htp-mem.h"
 
#include "util-host-os-info.h"
#include "util-privs.h"
#include "util-profiling.h"
#include "util-misc.h"
#include "util-validate.h"
#include "util-runmodes.h"
#include "util-random.h"
#include "util-exception-policy.h"
#include "util-time.h"
 
#include "source-pcap-file.h"
#include "action-globals.h"
 
//#define DEBUG
 
#define STREAMTCP_DEFAULT_PREALLOC              2048
#define STREAMTCP_DEFAULT_MEMCAP                (64 * 1024 * 1024)  /* 64mb */
#define STREAMTCP_DEFAULT_REASSEMBLY_MEMCAP     (256 * 1024 * 1024) /* 256mb */
#define STREAMTCP_DEFAULT_TOSERVER_CHUNK_SIZE   2560
#define STREAMTCP_DEFAULT_TOCLIENT_CHUNK_SIZE   2560
#define STREAMTCP_DEFAULT_MAX_SYNACK_QUEUED     5
 
static int StreamTcpHandleFin(ThreadVars *tv, StreamTcpThread *, TcpSession *, Packet *, PacketQueueNoLock *);
void StreamTcpReturnStreamSegments (TcpStream *);
void StreamTcpInitConfig(bool);
int StreamTcpGetFlowState(void *);
void StreamTcpSetOSPolicy(TcpStream*, Packet*);
 
static int StreamTcpValidateTimestamp(TcpSession * , Packet *);
static int StreamTcpHandleTimestamp(TcpSession * , Packet *);
static int StreamTcpValidateRst(TcpSession * , Packet *);
static inline int StreamTcpValidateAck(TcpSession *ssn, TcpStream *, Packet *);
static int StreamTcpStateDispatch(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq,
        uint8_t state);
 
extern thread_local uint64_t t_pcapcnt;
extern int g_detect_disabled;
 
PoolThread *ssn_pool = NULL;
static SCMutex ssn_pool_mutex = SCMUTEX_INITIALIZER; /**< init only, protect initializing and growing pool */
#ifdef DEBUG
static uint64_t ssn_pool_cnt = 0; /** counts ssns, protected by ssn_pool_mutex */
#endif
 
TcpStreamCnf stream_config;
uint64_t StreamTcpReassembleMemuseGlobalCounter(void);
SC_ATOMIC_DECLARE(uint64_t, st_memuse);
 
void StreamTcpInitMemuse(void)
{
    SC_ATOMIC_INIT(st_memuse);
}
 
void StreamTcpIncrMemuse(uint64_t size)
{
    (void) SC_ATOMIC_ADD(st_memuse, size);
    SCLogDebug("STREAM %"PRIu64", incr %"PRIu64, StreamTcpMemuseCounter(), size);
    return;
}
 
void StreamTcpDecrMemuse(uint64_t size)
{
#ifdef DEBUG_VALIDATION
    uint64_t presize = SC_ATOMIC_GET(st_memuse);
    if (RunmodeIsUnittests()) {
        BUG_ON(presize > UINT_MAX);
    }
#endif
 
    (void) SC_ATOMIC_SUB(st_memuse, size);
 
#ifdef DEBUG_VALIDATION
    if (RunmodeIsUnittests()) {
        uint64_t postsize = SC_ATOMIC_GET(st_memuse);
        BUG_ON(postsize > presize);
    }
#endif
    SCLogDebug("STREAM %"PRIu64", decr %"PRIu64, StreamTcpMemuseCounter(), size);
    return;
}
 
uint64_t StreamTcpMemuseCounter(void)
{
    uint64_t memusecopy = SC_ATOMIC_GET(st_memuse);
    return memusecopy;
}
 
/**
 *  \brief Check if alloc'ing "size" would mean we're over memcap
 *
 *  \retval 1 if in bounds
 *  \retval 0 if not in bounds
 */
int StreamTcpCheckMemcap(uint64_t size)
{
    uint64_t memcapcopy = SC_ATOMIC_GET(stream_config.memcap);
    if (memcapcopy == 0 || size + SC_ATOMIC_GET(st_memuse) <= memcapcopy)
        return 1;
    return 0;
}
 
/**
 *  \brief Update memcap value
 *
 *  \param size new memcap value
 */
int StreamTcpSetMemcap(uint64_t size)
{
    if (size == 0 || (uint64_t)SC_ATOMIC_GET(st_memuse) < size) {
        SC_ATOMIC_SET(stream_config.memcap, size);
        return 1;
    }
 
    return 0;
}
 
/**
 *  \brief Return memcap value
 *
 *  \param memcap memcap value
 */
uint64_t StreamTcpGetMemcap(void)
{
    uint64_t memcapcopy = SC_ATOMIC_GET(stream_config.memcap);
    return memcapcopy;
}
 
void StreamTcpStreamCleanup(TcpStream *stream)
{
    if (stream != NULL) {
        StreamTcpSackFreeList(stream);
        StreamTcpReturnStreamSegments(stream);
        StreamingBufferClear(&stream->sb, &stream_config.sbcnf);
    }
}
 
/**
 *  \brief Session cleanup function. Does not free the ssn.
 *  \param ssn tcp session
 */
void StreamTcpSessionCleanup(TcpSession *ssn)
{
    SCEnter();
    TcpStateQueue *q, *q_next;
 
    if (ssn == NULL)
        return;
 
    StreamTcpStreamCleanup(&ssn->client);
    StreamTcpStreamCleanup(&ssn->server);
 
    q = ssn->queue;
    while (q != NULL) {
        q_next = q->next;
        SCFree(q);
        q = q_next;
        StreamTcpDecrMemuse((uint64_t)sizeof(TcpStateQueue));
    }
    ssn->queue = NULL;
    ssn->queue_len = 0;
 
    SCReturn;
}
 
/**
 *  \brief Function to return the stream back to the pool. It returns the
 *         segments in the stream to the segment pool.
 *
 *  This function is called when the flow is destroyed, so it should free
 *  *everything* related to the tcp session. So including the app layer
 *  data.
 *
 *  \param ssn Void ptr to the ssn.
 */
void StreamTcpSessionClear(void *ssnptr)
{
    SCEnter();
    TcpSession *ssn = (TcpSession *)ssnptr;
    if (ssn == NULL)
        return;
 
    StreamTcpSessionCleanup(ssn);
 
    /* HACK: don't loose track of thread id */
    PoolThreadId pool_id = ssn->pool_id;
    memset(ssn, 0, sizeof(TcpSession));
    ssn->pool_id = pool_id;
 
    StreamTcpThreadCacheReturnSession(ssn);
#ifdef DEBUG
    SCMutexLock(&ssn_pool_mutex);
    ssn_pool_cnt--;
    SCMutexUnlock(&ssn_pool_mutex);
#endif
 
    SCReturn;
}
 
/**
 *  \brief Function to return the stream segments back to the pool.
 *
 *  \param p Packet used to identify the stream.
 */
void StreamTcpSessionPktFree (Packet *p)
{
    SCEnter();
 
    TcpSession *ssn = (TcpSession *)p->flow->protoctx;
    if (ssn == NULL)
        SCReturn;
 
    StreamTcpReturnStreamSegments(&ssn->client);
    StreamTcpReturnStreamSegments(&ssn->server);
 
    SCReturn;
}
 
/** \brief Stream alloc function for the Pool
 *  \retval ptr void ptr to TcpSession structure with all vars set to 0/NULL
 */
static void *StreamTcpSessionPoolAlloc(void)
{
    void *ptr = NULL;
 
    if (StreamTcpCheckMemcap((uint32_t)sizeof(TcpSession)) == 0)
        return NULL;
 
    ptr = SCMalloc(sizeof(TcpSession));
    if (unlikely(ptr == NULL))
        return NULL;
 
    return ptr;
}
 
static int StreamTcpSessionPoolInit(void *data, void* initdata)
{
    memset(data, 0, sizeof(TcpSession));
    StreamTcpIncrMemuse((uint64_t)sizeof(TcpSession));
 
    return 1;
}
 
/** \brief Pool cleanup function
 *  \param s Void ptr to TcpSession memory */
static void StreamTcpSessionPoolCleanup(void *s)
{
    if (s != NULL) {
        StreamTcpSessionCleanup(s);
        /** \todo not very clean, as the memory is not freed here */
        StreamTcpDecrMemuse((uint64_t)sizeof(TcpSession));
    }
}
 
/**
 *  \brief See if stream engine is dropping invalid packet in inline mode
 *
 *  \retval 0 no
 *  \retval 1 yes
 */
int StreamTcpInlineDropInvalid(void)
{
    return ((stream_config.flags & STREAMTCP_INIT_FLAG_INLINE)
            && (stream_config.flags & STREAMTCP_INIT_FLAG_DROP_INVALID));
}
 
/* hack: stream random range code expects random values in range of 0-RAND_MAX,
 * but we can get both <0 and >RAND_MAX values from RandomGet
 */
static int RandomGetWrap(void)
{
    unsigned long r;
 
    do {
        r = RandomGet();
    } while(r >= ULONG_MAX - (ULONG_MAX % RAND_MAX));
 
    return r % RAND_MAX;
}
 
/** \brief          To initialize the stream global configuration data
 *
 *  \param  quiet   It tells the mode of operation, if it is true nothing will
 *                  be get printed.
 */
 
void StreamTcpInitConfig(bool quiet)
{
    intmax_t value = 0;
    uint16_t rdrange = 10;
 
    SCLogDebug("Initializing Stream");
 
    memset(&stream_config,  0, sizeof(stream_config));
 
    SC_ATOMIC_INIT(stream_config.memcap);
    SC_ATOMIC_INIT(stream_config.reassembly_memcap);
 
    if ((ConfGetInt("stream.max-sessions", &value)) == 1) {
        SCLogWarning("max-sessions is obsolete. "
                     "Number of concurrent sessions is now only limited by Flow and "
                     "TCP stream engine memcaps.");
    }
 
    if ((ConfGetInt("stream.prealloc-sessions", &value)) == 1) {
        stream_config.prealloc_sessions = (uint32_t)value;
    } else {
        if (RunmodeIsUnittests()) {
            stream_config.prealloc_sessions = 128;
        } else {
            stream_config.prealloc_sessions = STREAMTCP_DEFAULT_PREALLOC;
            if (ConfGetNode("stream.prealloc-sessions") != NULL) {
                WarnInvalidConfEntry("stream.prealloc_sessions",
                                     "%"PRIu32,
                                     stream_config.prealloc_sessions);
            }
        }
    }
    if (!quiet) {
        SCLogConfig("stream \"prealloc-sessions\": %"PRIu32" (per thread)",
                stream_config.prealloc_sessions);
    }
 
    const char *temp_stream_memcap_str;
    if (ConfGet("stream.memcap", &temp_stream_memcap_str) == 1) {
        uint64_t stream_memcap_copy;
        if (ParseSizeStringU64(temp_stream_memcap_str, &stream_memcap_copy) < 0) {
            SCLogError("Error parsing stream.memcap "
                       "from conf file - %s.  Killing engine",
                    temp_stream_memcap_str);
            exit(EXIT_FAILURE);
        } else {
            SC_ATOMIC_SET(stream_config.memcap, stream_memcap_copy);
        }
    } else {
        SC_ATOMIC_SET(stream_config.memcap, STREAMTCP_DEFAULT_MEMCAP);
    }
 
    if (!quiet) {
        SCLogConfig("stream \"memcap\": %"PRIu64, SC_ATOMIC_GET(stream_config.memcap));
    }
 
    int imidstream;
    (void)ConfGetBool("stream.midstream", &imidstream);
    stream_config.midstream = imidstream != 0;
 
    if (!quiet) {
        SCLogConfig("stream \"midstream\" session pickups: %s", stream_config.midstream ? "enabled" : "disabled");
    }
 
    (void)ConfGetBool("stream.async-oneside", &stream_config.async_oneside);
 
    if (!quiet) {
        SCLogConfig("stream \"async-oneside\": %s", stream_config.async_oneside ? "enabled" : "disabled");
    }
 
    int csum = 0;
 
    if ((ConfGetBool("stream.checksum-validation", &csum)) == 1) {
        if (csum == 1) {
            stream_config.flags |= STREAMTCP_INIT_FLAG_CHECKSUM_VALIDATION;
        }
    /* Default is that we validate the checksum of all the packets */
    } else {
        stream_config.flags |= STREAMTCP_INIT_FLAG_CHECKSUM_VALIDATION;
    }
 
    if (!quiet) {
        SCLogConfig("stream \"checksum-validation\": %s",
                stream_config.flags & STREAMTCP_INIT_FLAG_CHECKSUM_VALIDATION ?
                "enabled" : "disabled");
    }
 
    const char *temp_stream_inline_str;
    if (ConfGet("stream.inline", &temp_stream_inline_str) == 1) {
        int inl = 0;
 
        /* checking for "auto" and falling back to boolean to provide
         * backward compatibility */
        if (strcmp(temp_stream_inline_str, "auto") == 0) {
            if (EngineModeIsIPS()) {
                stream_config.flags |= STREAMTCP_INIT_FLAG_INLINE;
            }
        } else if (ConfGetBool("stream.inline", &inl) == 1) {
            if (inl) {
                stream_config.flags |= STREAMTCP_INIT_FLAG_INLINE;
            }
        }
    } else {
        /* default to 'auto' */
        if (EngineModeIsIPS()) {
            stream_config.flags |= STREAMTCP_INIT_FLAG_INLINE;
        }
    }
    stream_config.ssn_memcap_policy = ExceptionPolicyParse("stream.memcap-policy", true);
    stream_config.reassembly_memcap_policy =
            ExceptionPolicyParse("stream.reassembly.memcap-policy", true);
    stream_config.midstream_policy = ExceptionPolicyParse("stream.midstream-policy", true);
    if (stream_config.midstream && stream_config.midstream_policy != EXCEPTION_POLICY_NOT_SET) {
        SCLogWarning("stream.midstream_policy setting conflicting with stream.midstream enabled. "
                     "Ignoring stream.midstream_policy. Bug #5825.");
        stream_config.midstream_policy = EXCEPTION_POLICY_NOT_SET;
    }
 
    if (!quiet) {
        SCLogConfig("stream.\"inline\": %s",
                    stream_config.flags & STREAMTCP_INIT_FLAG_INLINE
                    ? "enabled" : "disabled");
    }
 
    int bypass = 0;
    if ((ConfGetBool("stream.bypass", &bypass)) == 1) {
        if (bypass == 1) {
            stream_config.flags |= STREAMTCP_INIT_FLAG_BYPASS;
        }
    }
 
    if (!quiet) {
        SCLogConfig("stream \"bypass\": %s",
                    (stream_config.flags & STREAMTCP_INIT_FLAG_BYPASS)
                    ? "enabled" : "disabled");
    }
 
    int drop_invalid = 0;
    if ((ConfGetBool("stream.drop-invalid", &drop_invalid)) == 1) {
        if (drop_invalid == 1) {
            stream_config.flags |= STREAMTCP_INIT_FLAG_DROP_INVALID;
        }
    } else {
        stream_config.flags |= STREAMTCP_INIT_FLAG_DROP_INVALID;
    }
 
    if ((ConfGetInt("stream.max-synack-queued", &value)) == 1) {
        if (value >= 0 && value <= 255) {
            stream_config.max_synack_queued = (uint8_t)value;
        } else {
            stream_config.max_synack_queued = (uint8_t)STREAMTCP_DEFAULT_MAX_SYNACK_QUEUED;
        }
    } else {
        stream_config.max_synack_queued = (uint8_t)STREAMTCP_DEFAULT_MAX_SYNACK_QUEUED;
    }
    if (!quiet) {
        SCLogConfig("stream \"max-synack-queued\": %"PRIu8, stream_config.max_synack_queued);
    }
 
    const char *temp_stream_reassembly_memcap_str;
    if (ConfGet("stream.reassembly.memcap", &temp_stream_reassembly_memcap_str) == 1) {
        uint64_t stream_reassembly_memcap_copy;
        if (ParseSizeStringU64(temp_stream_reassembly_memcap_str,
                               &stream_reassembly_memcap_copy) < 0) {
            SCLogError("Error parsing "
                       "stream.reassembly.memcap "
                       "from conf file - %s.  Killing engine",
                    temp_stream_reassembly_memcap_str);
            exit(EXIT_FAILURE);
        } else {
            SC_ATOMIC_SET(stream_config.reassembly_memcap, stream_reassembly_memcap_copy);
        }
    } else {
        SC_ATOMIC_SET(stream_config.reassembly_memcap , STREAMTCP_DEFAULT_REASSEMBLY_MEMCAP);
    }
 
    if (!quiet) {
        SCLogConfig("stream.reassembly \"memcap\": %"PRIu64"",
                    SC_ATOMIC_GET(stream_config.reassembly_memcap));
    }
 
    const char *temp_stream_reassembly_depth_str;
    if (ConfGet("stream.reassembly.depth", &temp_stream_reassembly_depth_str) == 1) {
        if (ParseSizeStringU32(temp_stream_reassembly_depth_str,
                               &stream_config.reassembly_depth) < 0) {
            SCLogError("Error parsing "
                       "stream.reassembly.depth "
                       "from conf file - %s.  Killing engine",
                    temp_stream_reassembly_depth_str);
            exit(EXIT_FAILURE);
        }
    } else {
        stream_config.reassembly_depth = 0;
    }
 
    if (!quiet) {
        SCLogConfig("stream.reassembly \"depth\": %"PRIu32"", stream_config.reassembly_depth);
    }
 
    int randomize = 0;
    if ((ConfGetBool("stream.reassembly.randomize-chunk-size", &randomize)) == 0) {
        /* randomize by default if value not set
         * In ut mode we disable, to get predictable test results */
        if (!(RunmodeIsUnittests()))
            randomize = 1;
    }
 
    if (randomize) {
        const char *temp_rdrange;
        if (ConfGet("stream.reassembly.randomize-chunk-range", &temp_rdrange) == 1) {
            if (ParseSizeStringU16(temp_rdrange, &rdrange) < 0) {
                SCLogError("Error parsing "
                           "stream.reassembly.randomize-chunk-range "
                           "from conf file - %s.  Killing engine",
                        temp_rdrange);
                exit(EXIT_FAILURE);
            } else if (rdrange >= 100) {
                FatalError("stream.reassembly.randomize-chunk-range "
                           "must be lower than 100");
            }
        }
    }
 
    const char *temp_stream_reassembly_toserver_chunk_size_str;
    if (ConfGet("stream.reassembly.toserver-chunk-size",
                &temp_stream_reassembly_toserver_chunk_size_str) == 1) {
        if (ParseSizeStringU16(temp_stream_reassembly_toserver_chunk_size_str,
                               &stream_config.reassembly_toserver_chunk_size) < 0) {
            SCLogError("Error parsing "
                       "stream.reassembly.toserver-chunk-size "
                       "from conf file - %s.  Killing engine",
                    temp_stream_reassembly_toserver_chunk_size_str);
            exit(EXIT_FAILURE);
        }
    } else {
        stream_config.reassembly_toserver_chunk_size =
            STREAMTCP_DEFAULT_TOSERVER_CHUNK_SIZE;
    }
 
    if (randomize) {
        long int r = RandomGetWrap();
        stream_config.reassembly_toserver_chunk_size +=
                (int)(stream_config.reassembly_toserver_chunk_size * ((double)r / RAND_MAX - 0.5) *
                        rdrange / 100);
    }
    const char *temp_stream_reassembly_toclient_chunk_size_str;
    if (ConfGet("stream.reassembly.toclient-chunk-size",
                &temp_stream_reassembly_toclient_chunk_size_str) == 1) {
        if (ParseSizeStringU16(temp_stream_reassembly_toclient_chunk_size_str,
                               &stream_config.reassembly_toclient_chunk_size) < 0) {
            SCLogError("Error parsing "
                       "stream.reassembly.toclient-chunk-size "
                       "from conf file - %s.  Killing engine",
                    temp_stream_reassembly_toclient_chunk_size_str);
            exit(EXIT_FAILURE);
        }
    } else {
        stream_config.reassembly_toclient_chunk_size =
            STREAMTCP_DEFAULT_TOCLIENT_CHUNK_SIZE;
    }
 
    if (randomize) {
        long int r = RandomGetWrap();
        stream_config.reassembly_toclient_chunk_size +=
                (int)(stream_config.reassembly_toclient_chunk_size * ((double)r / RAND_MAX - 0.5) *
                        rdrange / 100);
    }
    if (!quiet) {
        SCLogConfig("stream.reassembly \"toserver-chunk-size\": %"PRIu16,
            stream_config.reassembly_toserver_chunk_size);
        SCLogConfig("stream.reassembly \"toclient-chunk-size\": %"PRIu16,
            stream_config.reassembly_toclient_chunk_size);
    }
 
    int enable_raw = 1;
    if (ConfGetBool("stream.reassembly.raw", &enable_raw) == 1) {
        if (!enable_raw) {
            stream_config.stream_init_flags = STREAMTCP_STREAM_FLAG_DISABLE_RAW;
        }
    } else {
        enable_raw = 1;
    }
    if (!quiet)
        SCLogConfig("stream.reassembly.raw: %s", enable_raw ? "enabled" : "disabled");
 
    /* init the memcap/use tracking */
    StreamTcpInitMemuse();
    StatsRegisterGlobalCounter("tcp.memuse", StreamTcpMemuseCounter);
 
    StreamTcpReassembleInit(quiet);
 
    /* set the default free function and flow state function
     * values. */
    FlowSetProtoFreeFunc(IPPROTO_TCP, StreamTcpSessionClear);
 
#ifdef UNITTESTS
    if (RunmodeIsUnittests()) {
        SCMutexLock(&ssn_pool_mutex);
        if (ssn_pool == NULL) {
            ssn_pool = PoolThreadInit(1, /* thread */
                    0, /* unlimited */
                    stream_config.prealloc_sessions,
                    sizeof(TcpSession),
                    StreamTcpSessionPoolAlloc,
                    StreamTcpSessionPoolInit, NULL,
                    StreamTcpSessionPoolCleanup, NULL);
        }
        SCMutexUnlock(&ssn_pool_mutex);
    }
#endif
}
 
void StreamTcpFreeConfig(bool quiet)
{
    StreamTcpReassembleFree(quiet);
 
    SCMutexLock(&ssn_pool_mutex);
    if (ssn_pool != NULL) {
        PoolThreadFree(ssn_pool);
        ssn_pool = NULL;
    }
    SCMutexUnlock(&ssn_pool_mutex);
    SCMutexDestroy(&ssn_pool_mutex);
 
    SCLogDebug("ssn_pool_cnt %"PRIu64"", ssn_pool_cnt);
}
 
/** \internal
 *  \brief The function is used to fetch a TCP session from the
 *         ssn_pool, when a TCP SYN is received.
 *
 *  \param p packet starting the new TCP session.
 *  \param id thread pool id
 *
 *  \retval ssn new TCP session.
 */
static TcpSession *StreamTcpNewSession(ThreadVars *tv, StreamTcpThread *stt, Packet *p, int id)
{
    TcpSession *ssn = (TcpSession *)p->flow->protoctx;
 
    if (ssn == NULL) {
        DEBUG_VALIDATE_BUG_ON(id < 0 || id > UINT16_MAX);
        p->flow->protoctx = StreamTcpThreadCacheGetSession();
        if (p->flow->protoctx != NULL) {
#ifdef UNITTESTS
            if (tv)
#endif
                StatsIncr(tv, stt->counter_tcp_ssn_from_cache);
        } else {
            p->flow->protoctx = PoolThreadGetById(ssn_pool, (uint16_t)id);
            if (p->flow->protoctx != NULL)
#ifdef UNITTESTS
                if (tv)
#endif
                    StatsIncr(tv, stt->counter_tcp_ssn_from_pool);
        }
#ifdef DEBUG
        SCMutexLock(&ssn_pool_mutex);
        if (p->flow->protoctx != NULL)
            ssn_pool_cnt++;
        SCMutexUnlock(&ssn_pool_mutex);
 
        if (unlikely((g_eps_stream_ssn_memcap != UINT64_MAX &&
                      g_eps_stream_ssn_memcap == t_pcapcnt))) {
            SCLogNotice("simulating memcap reached condition for packet %" PRIu64, t_pcapcnt);
            ExceptionPolicyApply(p, stream_config.ssn_memcap_policy, PKT_DROP_REASON_STREAM_MEMCAP);
            return NULL;
        }
#endif
        ssn = (TcpSession *)p->flow->protoctx;
        if (ssn == NULL) {
            SCLogDebug("ssn_pool is empty");
            ExceptionPolicyApply(p, stream_config.ssn_memcap_policy, PKT_DROP_REASON_STREAM_MEMCAP);
            return NULL;
        }
 
        ssn->state = TCP_NONE;
        ssn->reassembly_depth = stream_config.reassembly_depth;
        ssn->tcp_packet_flags = p->tcph ? p->tcph->th_flags : 0;
        ssn->server.flags = stream_config.stream_init_flags;
        ssn->client.flags = stream_config.stream_init_flags;
 
        StreamingBuffer x = STREAMING_BUFFER_INITIALIZER;
        ssn->client.sb = x;
        ssn->server.sb = x;
 
        if (PKT_IS_TOSERVER(p)) {
            ssn->client.tcp_flags = p->tcph ? p->tcph->th_flags : 0;
            ssn->server.tcp_flags = 0;
        } else if (PKT_IS_TOCLIENT(p)) {
            ssn->server.tcp_flags = p->tcph ? p->tcph->th_flags : 0;
            ssn->client.tcp_flags = 0;
        }
    }
 
    return ssn;
}
 
static void StreamTcpPacketSetState(Packet *p, TcpSession *ssn,
                                           uint8_t state)
{
    if (state == ssn->state || PKT_IS_PSEUDOPKT(p))
        return;
 
    ssn->pstate = ssn->state;
    ssn->state = state;
 
    /* update the flow state */
    switch(ssn->state) {
        case TCP_ESTABLISHED:
        case TCP_FIN_WAIT1:
        case TCP_FIN_WAIT2:
        case TCP_CLOSING:
        case TCP_CLOSE_WAIT:
            FlowUpdateState(p->flow, FLOW_STATE_ESTABLISHED);
            break;
        case TCP_LAST_ACK:
        case TCP_TIME_WAIT:
        case TCP_CLOSED:
            FlowUpdateState(p->flow, FLOW_STATE_CLOSED);
            break;
    }
}
 
/**
 *  \brief  Function to set the OS policy for the given stream based on the
 *          destination of the received packet.
 *
 *  \param  stream  TcpStream of which os_policy needs to set
 *  \param  p       Packet which is used to set the os policy
 */
void StreamTcpSetOSPolicy(TcpStream *stream, Packet *p)
{
    if (PKT_IS_IPV4(p)) {
        /* Get the OS policy based on destination IP address, as destination
           OS will decide how to react on the anomalies of newly received
           packets */
        int ret = SCHInfoGetIPv4HostOSFlavour((uint8_t *)GET_IPV4_DST_ADDR_PTR(p));
        if (ret > 0)
            stream->os_policy = (uint8_t)ret;
        else
            stream->os_policy = OS_POLICY_DEFAULT;
 
    } else if (PKT_IS_IPV6(p)) {
        /* Get the OS policy based on destination IP address, as destination
           OS will decide how to react on the anomalies of newly received
           packets */
        int ret = SCHInfoGetIPv6HostOSFlavour((uint8_t *)GET_IPV6_DST_ADDR(p));
        if (ret > 0)
            stream->os_policy = (uint8_t)ret;
        else
            stream->os_policy = OS_POLICY_DEFAULT;
    }
 
    if (stream->os_policy == OS_POLICY_BSD_RIGHT)
        stream->os_policy = OS_POLICY_BSD;
    else if (stream->os_policy == OS_POLICY_OLD_SOLARIS)
        stream->os_policy = OS_POLICY_SOLARIS;
 
    SCLogDebug("Policy is %"PRIu8"", stream->os_policy);
 
}
 
/**
 *  \brief macro to update last_ack only if the new value is higher
 *
 *  \param ssn session
 *  \param stream stream to update
 *  \param ack ACK value to test and set
 */
#define StreamTcpUpdateLastAck(ssn, stream, ack) { \
    if (SEQ_GT((ack), (stream)->last_ack)) \
    { \
        SCLogDebug("ssn %p: last_ack set to %"PRIu32", moved %u forward", (ssn), (ack), (ack) - (stream)->last_ack); \
        if ((SEQ_LEQ((stream)->last_ack, (stream)->next_seq) && SEQ_GT((ack),(stream)->next_seq))) { \
            SCLogDebug("last_ack just passed next_seq: %u (was %u) > %u", (ack), (stream)->last_ack, (stream)->next_seq); \
        } else { \
            SCLogDebug("next_seq (%u) <> last_ack now %d", (stream)->next_seq, (int)(stream)->next_seq - (ack)); \
        }\
        (stream)->last_ack = (ack); \
        StreamTcpSackPruneList((stream)); \
    } else { \
        SCLogDebug("ssn %p: no update: ack %u, last_ack %"PRIu32", next_seq %u (state %u)", \
                    (ssn), (ack), (stream)->last_ack, (stream)->next_seq, (ssn)->state); \
    }\
}
 
#define StreamTcpAsyncLastAckUpdate(ssn, stream) {                              \
    if ((ssn)->flags & STREAMTCP_FLAG_ASYNC) {                                  \
        if (SEQ_GT((stream)->next_seq, (stream)->last_ack)) {                   \
            uint32_t ack_diff = (stream)->next_seq - (stream)->last_ack;        \
            (stream)->last_ack += ack_diff;                                     \
            SCLogDebug("ssn %p: ASYNC last_ack set to %"PRIu32", moved %u forward",     \
                    (ssn), (stream)->next_seq, ack_diff);                               \
        }                                                                       \
    }                                                                           \
}
 
#define StreamTcpUpdateNextSeq(ssn, stream, seq) {                      \
    (stream)->next_seq = seq;                                           \
    SCLogDebug("ssn %p: next_seq %" PRIu32, (ssn), (stream)->next_seq); \
    StreamTcpAsyncLastAckUpdate((ssn), (stream));                       \
}
 
/**
 *  \brief macro to update next_win only if the new value is higher
 *
 *  \param ssn session
 *  \param stream stream to update
 *  \param win window value to test and set
 */
#define StreamTcpUpdateNextWin(ssn, stream, win) { \
    uint32_t sacked_size__ = StreamTcpSackedSize((stream)); \
    if (SEQ_GT(((win) + sacked_size__), (stream)->next_win)) { \
        (stream)->next_win = ((win) + sacked_size__); \
        SCLogDebug("ssn %p: next_win set to %"PRIu32, (ssn), (stream)->next_win); \
    } \
}
 
static inline void StreamTcpCloseSsnWithReset(Packet *p, TcpSession *ssn)
{
    ssn->flags |= STREAMTCP_FLAG_CLOSED_BY_RST;
    StreamTcpPacketSetState(p, ssn, TCP_CLOSED);
    SCLogDebug("ssn %p: (state: %s) Reset received and state changed to "
            "TCP_CLOSED", ssn, StreamTcpStateAsString(ssn->state));
}
 
static int StreamTcpPacketIsRetransmission(TcpStream *stream, Packet *p)
{
    if (p->payload_len == 0)
        SCReturnInt(0);
 
    /* retransmission of already partially ack'd data */
    if (SEQ_LT(TCP_GET_SEQ(p), stream->last_ack) && SEQ_GT((TCP_GET_SEQ(p) + p->payload_len), stream->last_ack))
    {
        StreamTcpSetEvent(p, STREAM_PKT_RETRANSMISSION);
        SCReturnInt(1);
    }
 
    /* retransmission of already ack'd data */
    if (SEQ_LEQ((TCP_GET_SEQ(p) + p->payload_len), stream->last_ack)) {
        StreamTcpSetEvent(p, STREAM_PKT_RETRANSMISSION);
        SCReturnInt(1);
    }
 
    /* retransmission of in flight data */
    if (SEQ_LEQ((TCP_GET_SEQ(p) + p->payload_len), stream->next_seq)) {
        StreamTcpSetEvent(p, STREAM_PKT_RETRANSMISSION);
        SCReturnInt(2);
    }
 
    SCLogDebug("seq %u payload_len %u => %u, last_ack %u, next_seq %u", TCP_GET_SEQ(p),
            p->payload_len, (TCP_GET_SEQ(p) + p->payload_len), stream->last_ack, stream->next_seq);
    SCReturnInt(0);
}
 
/**
 *  \internal
 *  \brief  Function to handle the TCP_CLOSED or NONE state. The function handles
 *          packets while the session state is None which means a newly
 *          initialized structure, or a fully closed session.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Stream Thread module registered to handle the stream handling
 *
 *  \retval 0 ok
 *  \retval -1 error
 */
static int StreamTcpPacketStateNone(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn,
        PacketQueueNoLock *pq)
{
    if (p->tcph->th_flags & TH_RST) {
        StreamTcpSetEvent(p, STREAM_RST_BUT_NO_SESSION);
        SCLogDebug("RST packet received, no session setup");
        return -1;
 
    } else if (p->tcph->th_flags & TH_FIN) {
        StreamTcpSetEvent(p, STREAM_FIN_BUT_NO_SESSION);
        SCLogDebug("FIN packet received, no session setup");
        return -1;
 
    /* SYN/ACK */
    } else if ((p->tcph->th_flags & (TH_SYN | TH_ACK)) == (TH_SYN | TH_ACK)) {
        /* Drop reason will only be used if midstream policy is set to fail closed */
        ExceptionPolicyApply(p, stream_config.midstream_policy, PKT_DROP_REASON_STREAM_MIDSTREAM);
 
        if (!stream_config.midstream && stream_config.async_oneside == FALSE) {
            SCLogDebug("Midstream not enabled, so won't pick up a session");
            return 0;
        }
        if (!(stream_config.midstream_policy == EXCEPTION_POLICY_NOT_SET ||
                    stream_config.midstream_policy == EXCEPTION_POLICY_PASS_FLOW ||
                    stream_config.midstream_policy == EXCEPTION_POLICY_PASS_PACKET)) {
            SCLogDebug("Midstream policy not permissive, so won't pick up a session");
            return 0;
        }
        SCLogDebug("midstream picked up");
 
        if (ssn == NULL) {
            ssn = StreamTcpNewSession(tv, stt, p, stt->ssn_pool_id);
            if (ssn == NULL) {
                StatsIncr(tv, stt->counter_tcp_ssn_memcap);
                return -1;
            }
            StatsIncr(tv, stt->counter_tcp_sessions);
            StatsIncr(tv, stt->counter_tcp_active_sessions);
            StatsIncr(tv, stt->counter_tcp_midstream_pickups);
        }
 
        /* reverse packet and flow */
        SCLogDebug("reversing flow and packet");
        PacketSwap(p);
        FlowSwap(p->flow);
 
        /* set the state */
        StreamTcpPacketSetState(p, ssn, TCP_SYN_RECV);
        SCLogDebug("ssn %p: =~ midstream picked ssn state is now "
                "TCP_SYN_RECV", ssn);
        ssn->flags |= STREAMTCP_FLAG_MIDSTREAM;
        /* Flag used to change the direct in the later stage in the session */
        ssn->flags |= STREAMTCP_FLAG_MIDSTREAM_SYNACK;
        if (stream_config.async_oneside) {
            SCLogDebug("ssn %p: =~ ASYNC", ssn);
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
        }
 
        /* sequence number & window */
        ssn->server.isn = TCP_GET_SEQ(p);
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->server, ssn->server.isn);
        ssn->server.next_seq = ssn->server.isn + 1;
        ssn->server.window = TCP_GET_WINDOW(p);
        SCLogDebug("ssn %p: server window %u", ssn, ssn->server.window);
 
        ssn->client.isn = TCP_GET_ACK(p) - 1;
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->client, ssn->client.isn);
        ssn->client.next_seq = ssn->client.isn + 1;
 
        ssn->client.last_ack = TCP_GET_ACK(p);
        ssn->server.last_ack = TCP_GET_SEQ(p);
 
        ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
 
        /** If the client has a wscale option the server had it too,
         *  so set the wscale for the server to max. Otherwise none
         *  will have the wscale opt just like it should. */
        if (TCP_HAS_WSCALE(p)) {
            ssn->client.wscale = TCP_GET_WSCALE(p);
            ssn->server.wscale = TCP_WSCALE_MAX;
            SCLogDebug("ssn %p: wscale enabled. client %u server %u",
                    ssn, ssn->client.wscale, ssn->server.wscale);
        }
 
        SCLogDebug("ssn %p: ssn->client.isn %"PRIu32", ssn->client.next_seq"
                " %"PRIu32", ssn->client.last_ack %"PRIu32"", ssn,
                ssn->client.isn, ssn->client.next_seq,
                ssn->client.last_ack);
        SCLogDebug("ssn %p: ssn->server.isn %"PRIu32", ssn->server.next_seq"
                " %"PRIu32", ssn->server.last_ack %"PRIu32"", ssn,
                ssn->server.isn, ssn->server.next_seq,
                ssn->server.last_ack);
 
        /* Set the timestamp value for both streams, if packet has timestamp
         * option enabled.*/
        if (TCP_HAS_TS(p)) {
            ssn->server.last_ts = TCP_GET_TSVAL(p);
            ssn->client.last_ts = TCP_GET_TSECR(p);
            SCLogDebug("ssn %p: ssn->server.last_ts %" PRIu32" "
                    "ssn->client.last_ts %" PRIu32"", ssn,
                    ssn->server.last_ts, ssn->client.last_ts);
 
            ssn->flags |= STREAMTCP_FLAG_TIMESTAMP;
 
            ssn->server.last_pkt_ts = SCTIME_SECS(p->ts);
            if (ssn->server.last_ts == 0)
                ssn->server.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
            if (ssn->client.last_ts == 0)
                ssn->client.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
 
        } else {
            ssn->server.last_ts = 0;
            ssn->client.last_ts = 0;
        }
 
        if (TCP_GET_SACKOK(p) == 1) {
            ssn->flags |= STREAMTCP_FLAG_SACKOK;
            SCLogDebug("ssn %p: SYN/ACK with SACK permitted, assuming "
                    "SACK permitted for both sides", ssn);
        }
        return 0;
 
    } else if (p->tcph->th_flags & TH_SYN) {
        if (ssn == NULL) {
            ssn = StreamTcpNewSession(tv, stt, p, stt->ssn_pool_id);
            if (ssn == NULL) {
                StatsIncr(tv, stt->counter_tcp_ssn_memcap);
                return -1;
            }
 
            StatsIncr(tv, stt->counter_tcp_sessions);
            StatsIncr(tv, stt->counter_tcp_active_sessions);
        }
 
        /* set the state */
        StreamTcpPacketSetState(p, ssn, TCP_SYN_SENT);
        SCLogDebug("ssn %p: =~ ssn state is now TCP_SYN_SENT", ssn);
 
        if (stream_config.async_oneside) {
            SCLogDebug("ssn %p: =~ ASYNC", ssn);
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
        }
 
        /* set the sequence numbers and window */
        ssn->client.isn = TCP_GET_SEQ(p);
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->client, ssn->client.isn);
        ssn->client.next_seq = ssn->client.isn + 1;
 
        /* Set the stream timestamp value, if packet has timestamp option
         * enabled. */
        if (TCP_HAS_TS(p)) {
            ssn->client.last_ts = TCP_GET_TSVAL(p);
            SCLogDebug("ssn %p: %02x", ssn, ssn->client.last_ts);
 
            if (ssn->client.last_ts == 0)
                ssn->client.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
 
            ssn->client.last_pkt_ts = SCTIME_SECS(p->ts);
            ssn->client.flags |= STREAMTCP_STREAM_FLAG_TIMESTAMP;
        }
 
        ssn->server.window = TCP_GET_WINDOW(p);
        if (TCP_HAS_WSCALE(p)) {
            ssn->flags |= STREAMTCP_FLAG_SERVER_WSCALE;
            ssn->server.wscale = TCP_GET_WSCALE(p);
        }
 
        if (TCP_GET_SACKOK(p) == 1) {
            ssn->flags |= STREAMTCP_FLAG_CLIENT_SACKOK;
            SCLogDebug("ssn %p: SACK permitted on SYN packet", ssn);
        }
 
        if (TCP_HAS_TFO(p)) {
            ssn->flags |= STREAMTCP_FLAG_TCP_FAST_OPEN;
            if (p->payload_len) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
                SCLogDebug("ssn: %p (TFO) [len: %d] isn %u base_seq %u next_seq %u payload len %u",
                        ssn, p->tcpvars.tfo.len, ssn->client.isn, ssn->client.base_seq, ssn->client.next_seq, p->payload_len);
                StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->client, p, pq);
            }
        }
 
        SCLogDebug("ssn %p: ssn->client.isn %" PRIu32 ", "
                "ssn->client.next_seq %" PRIu32 ", ssn->client.last_ack "
                "%"PRIu32"", ssn, ssn->client.isn, ssn->client.next_seq,
                ssn->client.last_ack);
 
    } else if (p->tcph->th_flags & TH_ACK) {
        /* Drop reason will only be used if midstream policy is set to fail closed */
        ExceptionPolicyApply(p, stream_config.midstream_policy, PKT_DROP_REASON_STREAM_MIDSTREAM);
 
        if (!stream_config.midstream) {
            SCLogDebug("Midstream not enabled, so won't pick up a session");
            return 0;
        }
        if (!(stream_config.midstream_policy == EXCEPTION_POLICY_NOT_SET ||
                    stream_config.midstream_policy == EXCEPTION_POLICY_PASS_FLOW ||
                    stream_config.midstream_policy == EXCEPTION_POLICY_PASS_PACKET)) {
            SCLogDebug("Midstream policy not permissive, so won't pick up a session");
            return 0;
        }
        SCLogDebug("midstream picked up");
 
        if (ssn == NULL) {
            ssn = StreamTcpNewSession(tv, stt, p, stt->ssn_pool_id);
            if (ssn == NULL) {
                StatsIncr(tv, stt->counter_tcp_ssn_memcap);
                return -1;
            }
            StatsIncr(tv, stt->counter_tcp_sessions);
            StatsIncr(tv, stt->counter_tcp_active_sessions);
            StatsIncr(tv, stt->counter_tcp_midstream_pickups);
        }
        /* set the state */
        StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
        SCLogDebug("ssn %p: =~ midstream picked ssn state is now "
                "TCP_ESTABLISHED", ssn);
 
        ssn->flags = STREAMTCP_FLAG_MIDSTREAM;
        ssn->flags |= STREAMTCP_FLAG_MIDSTREAM_ESTABLISHED;
        if (stream_config.async_oneside) {
            SCLogDebug("ssn %p: =~ ASYNC", ssn);
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
        }
 
        /** window scaling for midstream pickups, we can't do much other
         *  than assume that it's set to the max value: 14 */
        ssn->client.wscale = TCP_WSCALE_MAX;
        ssn->server.wscale = TCP_WSCALE_MAX;
 
        /* set the sequence numbers and window */
        ssn->client.isn = TCP_GET_SEQ(p) - 1;
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->client, ssn->client.isn);
        ssn->client.next_seq = TCP_GET_SEQ(p) + p->payload_len;
        ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
        ssn->client.last_ack = TCP_GET_SEQ(p);
        ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
        SCLogDebug("ssn %p: ssn->client.isn %u, ssn->client.next_seq %u",
                ssn, ssn->client.isn, ssn->client.next_seq);
 
        ssn->server.isn = TCP_GET_ACK(p) - 1;
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->server, ssn->server.isn);
        ssn->server.next_seq = ssn->server.isn + 1;
        ssn->server.last_ack = TCP_GET_ACK(p);
        ssn->server.next_win = ssn->server.last_ack;
 
        SCLogDebug("ssn %p: ssn->client.next_win %"PRIu32", "
                "ssn->server.next_win %"PRIu32"", ssn,
                ssn->client.next_win, ssn->server.next_win);
        SCLogDebug("ssn %p: ssn->client.last_ack %"PRIu32", "
                "ssn->server.last_ack %"PRIu32"", ssn,
                ssn->client.last_ack, ssn->server.last_ack);
 
        /* Set the timestamp value for both streams, if packet has timestamp
         * option enabled.*/
        if (TCP_HAS_TS(p)) {
            ssn->client.last_ts = TCP_GET_TSVAL(p);
            ssn->server.last_ts = TCP_GET_TSECR(p);
            SCLogDebug("ssn %p: ssn->server.last_ts %" PRIu32" "
                    "ssn->client.last_ts %" PRIu32"", ssn,
                    ssn->server.last_ts, ssn->client.last_ts);
 
            ssn->flags |= STREAMTCP_FLAG_TIMESTAMP;
 
            ssn->client.last_pkt_ts = SCTIME_SECS(p->ts);
            if (ssn->server.last_ts == 0)
                ssn->server.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
            if (ssn->client.last_ts == 0)
                ssn->client.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
 
        } else {
            ssn->server.last_ts = 0;
            ssn->client.last_ts = 0;
        }
 
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->client, p, pq);
 
        ssn->flags |= STREAMTCP_FLAG_SACKOK;
        SCLogDebug("ssn %p: assuming SACK permitted for both sides", ssn);
 
    } else {
        SCLogDebug("default case");
    }
 
    return 0;
}
 
/** \internal
 *  \brief Setup TcpStateQueue based on SYN/ACK packet
 */
static inline void StreamTcp3whsSynAckToStateQueue(Packet *p, TcpStateQueue *q)
{
    q->flags = 0;
    q->wscale = 0;
    q->ts = 0;
    q->win = TCP_GET_WINDOW(p);
    q->seq = TCP_GET_SEQ(p);
    q->ack = TCP_GET_ACK(p);
    q->pkt_ts = SCTIME_SECS(p->ts);
 
    if (TCP_GET_SACKOK(p) == 1)
        q->flags |= STREAMTCP_QUEUE_FLAG_SACK;
 
    if (TCP_HAS_WSCALE(p)) {
        q->flags |= STREAMTCP_QUEUE_FLAG_WS;
        q->wscale = TCP_GET_WSCALE(p);
    }
    if (TCP_HAS_TS(p)) {
        q->flags |= STREAMTCP_QUEUE_FLAG_TS;
        q->ts = TCP_GET_TSVAL(p);
    }
}
 
/** \internal
 *  \brief Find the Queued SYN/ACK that is the same as this SYN/ACK
 *  \retval q or NULL */
static TcpStateQueue *StreamTcp3whsFindSynAckBySynAck(TcpSession *ssn, Packet *p)
{
    TcpStateQueue *q = ssn->queue;
    TcpStateQueue search;
 
    StreamTcp3whsSynAckToStateQueue(p, &search);
 
    while (q != NULL) {
        if (search.flags == q->flags &&
            search.wscale == q->wscale &&
            search.win == q->win &&
            search.seq == q->seq &&
            search.ack == q->ack &&
            search.ts == q->ts) {
            return q;
        }
 
        q = q->next;
    }
 
    return q;
}
 
static int StreamTcp3whsQueueSynAck(TcpSession *ssn, Packet *p)
{
    /* first see if this is already in our list */
    if (StreamTcp3whsFindSynAckBySynAck(ssn, p) != NULL)
        return 0;
 
    if (ssn->queue_len == stream_config.max_synack_queued) {
        SCLogDebug("ssn %p: =~ SYN/ACK queue limit reached", ssn);
        StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_FLOOD);
        return -1;
    }
 
    if (StreamTcpCheckMemcap((uint32_t)sizeof(TcpStateQueue)) == 0) {
        SCLogDebug("ssn %p: =~ SYN/ACK queue failed: stream memcap reached", ssn);
        return -1;
    }
 
    TcpStateQueue *q = SCMalloc(sizeof(*q));
    if (unlikely(q == NULL)) {
        SCLogDebug("ssn %p: =~ SYN/ACK queue failed: alloc failed", ssn);
        return -1;
    }
    memset(q, 0x00, sizeof(*q));
    StreamTcpIncrMemuse((uint64_t)sizeof(TcpStateQueue));
 
    StreamTcp3whsSynAckToStateQueue(p, q);
 
    /* put in list */
    q->next = ssn->queue;
    ssn->queue = q;
    ssn->queue_len++;
    return 0;
}
 
/** \internal
 *  \brief Find the Queued SYN/ACK that goes with this ACK
 *  \retval q or NULL */
static TcpStateQueue *StreamTcp3whsFindSynAckByAck(TcpSession *ssn, Packet *p)
{
    uint32_t ack = TCP_GET_SEQ(p);
    uint32_t seq = TCP_GET_ACK(p) - 1;
    TcpStateQueue *q = ssn->queue;
 
    while (q != NULL) {
        if (seq == q->seq &&
            ack == q->ack) {
            return q;
        }
 
        q = q->next;
    }
 
    return NULL;
}
 
/** \internal
 *  \brief Update SSN after receiving a valid SYN/ACK
 *
 *  Normally we update the SSN from the SYN/ACK packet. But in case
 *  of queued SYN/ACKs, we can use one of those.
 *
 *  \param ssn TCP session
 *  \param p Packet
 *  \param q queued state if used, NULL otherwise
 *
 *  To make sure all SYN/ACK based state updates are in one place,
 *  this function can updated based on Packet or TcpStateQueue, where
 *  the latter takes precedence.
 */
static void StreamTcp3whsSynAckUpdate(TcpSession *ssn, Packet *p, TcpStateQueue *q)
{
    TcpStateQueue update;
    if (likely(q == NULL)) {
        StreamTcp3whsSynAckToStateQueue(p, &update);
        q = &update;
    }
 
    if (ssn->state != TCP_SYN_RECV) {
        /* update state */
        StreamTcpPacketSetState(p, ssn, TCP_SYN_RECV);
        SCLogDebug("ssn %p: =~ ssn state is now TCP_SYN_RECV", ssn);
    }
    /* sequence number & window */
    ssn->server.isn = q->seq;
    STREAMTCP_SET_RA_BASE_SEQ(&ssn->server, ssn->server.isn);
    ssn->server.next_seq = ssn->server.isn + 1;
 
    ssn->client.window = q->win;
    SCLogDebug("ssn %p: window %" PRIu32 "", ssn, ssn->server.window);
 
    /* Set the timestamp values used to validate the timestamp of
     * received packets.*/
    if ((q->flags & STREAMTCP_QUEUE_FLAG_TS) &&
            (ssn->client.flags & STREAMTCP_STREAM_FLAG_TIMESTAMP))
    {
        ssn->server.last_ts = q->ts;
        SCLogDebug("ssn %p: ssn->server.last_ts %" PRIu32" "
                "ssn->client.last_ts %" PRIu32"", ssn,
                ssn->server.last_ts, ssn->client.last_ts);
        ssn->flags |= STREAMTCP_FLAG_TIMESTAMP;
        ssn->server.last_pkt_ts = q->pkt_ts;
        if (ssn->server.last_ts == 0)
            ssn->server.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
    } else {
        ssn->client.last_ts = 0;
        ssn->server.last_ts = 0;
        ssn->client.flags &= ~STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
    }
 
    ssn->client.last_ack = q->ack;
    ssn->server.last_ack = ssn->server.isn + 1;
 
    /** check for the presense of the ws ptr to determine if we
     *  support wscale at all */
    if ((ssn->flags & STREAMTCP_FLAG_SERVER_WSCALE) &&
            (q->flags & STREAMTCP_QUEUE_FLAG_WS))
    {
        ssn->client.wscale = q->wscale;
    } else {
        ssn->client.wscale = 0;
    }
 
    if ((ssn->flags & STREAMTCP_FLAG_CLIENT_SACKOK) &&
            (q->flags & STREAMTCP_QUEUE_FLAG_SACK)) {
        ssn->flags |= STREAMTCP_FLAG_SACKOK;
        SCLogDebug("ssn %p: SACK permitted for session", ssn);
    } else {
        ssn->flags &= ~STREAMTCP_FLAG_SACKOK;
    }
 
    ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
    ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
    SCLogDebug("ssn %p: ssn->server.next_win %" PRIu32 "", ssn,
            ssn->server.next_win);
    SCLogDebug("ssn %p: ssn->client.next_win %" PRIu32 "", ssn,
            ssn->client.next_win);
    SCLogDebug("ssn %p: ssn->server.isn %" PRIu32 ", "
            "ssn->server.next_seq %" PRIu32 ", "
            "ssn->server.last_ack %" PRIu32 " "
            "(ssn->client.last_ack %" PRIu32 ")", ssn,
            ssn->server.isn, ssn->server.next_seq,
            ssn->server.last_ack, ssn->client.last_ack);
 
    /* unset the 4WHS flag as we received this SYN/ACK as part of a
     * (so far) valid 3WHS */
    if (ssn->flags & STREAMTCP_FLAG_4WHS)
        SCLogDebug("ssn %p: STREAMTCP_FLAG_4WHS unset, normal SYN/ACK"
                " so considering 3WHS", ssn);
 
    ssn->flags &=~ STREAMTCP_FLAG_4WHS;
}
 
/** \internal
 *  \brief detect timestamp anomalies when processing responses to the
 *         SYN packet.
 *  \retval true packet is ok
 *  \retval false packet is bad
 */
static inline bool StateSynSentValidateTimestamp(TcpSession *ssn, Packet *p)
{
    /* we only care about evil server here, so skip TS packets */
    if (PKT_IS_TOSERVER(p) || !(TCP_HAS_TS(p))) {
        return true;
    }
 
    TcpStream *receiver_stream = &ssn->client;
    uint32_t ts_echo = TCP_GET_TSECR(p);
    if ((receiver_stream->flags & STREAMTCP_STREAM_FLAG_TIMESTAMP) != 0) {
        if (receiver_stream->last_ts != 0 && ts_echo != 0 &&
            ts_echo != receiver_stream->last_ts)
        {
            SCLogDebug("ssn %p: BAD TSECR echo %u recv %u", ssn,
                    ts_echo, receiver_stream->last_ts);
            return false;
        }
    } else {
        if (receiver_stream->last_ts == 0 && ts_echo != 0) {
            SCLogDebug("ssn %p: BAD TSECR echo %u recv %u", ssn,
                    ts_echo, receiver_stream->last_ts);
            return false;
        }
    }
    return true;
}
 
/**
 *  \brief  Function to handle the TCP_SYN_SENT state. The function handles
 *          SYN, SYN/ACK, RST packets and correspondingly changes the connection
 *          state.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateSynSent(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn,
        PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    SCLogDebug("ssn %p: pkt received: %s", ssn, PKT_IS_TOCLIENT(p) ?
               "toclient":"toserver");
 
    /* check for bad responses */
    if (StateSynSentValidateTimestamp(ssn, p) == false)
        return -1;
 
    /* RST */
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        if (PKT_IS_TOSERVER(p)) {
            if (SEQ_EQ(TCP_GET_SEQ(p), ssn->client.isn) &&
                    SEQ_EQ(TCP_GET_WINDOW(p), 0) &&
                    SEQ_EQ(TCP_GET_ACK(p), (ssn->client.isn + 1)))
            {
                SCLogDebug("ssn->server.flags |= STREAMTCP_STREAM_FLAG_RST_RECV");
                ssn->server.flags |= STREAMTCP_STREAM_FLAG_RST_RECV;
                StreamTcpCloseSsnWithReset(p, ssn);
            }
        } else {
            ssn->client.flags |= STREAMTCP_STREAM_FLAG_RST_RECV;
            SCLogDebug("ssn->client.flags |= STREAMTCP_STREAM_FLAG_RST_RECV");
            StreamTcpCloseSsnWithReset(p, ssn);
        }
 
    /* FIN */
    } else if (p->tcph->th_flags & TH_FIN) {
        /** \todo */
 
    /* SYN/ACK */
    } else if ((p->tcph->th_flags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) {
        if ((ssn->flags & STREAMTCP_FLAG_4WHS) && PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: SYN/ACK received on 4WHS session", ssn);
 
            /* Check if the SYN/ACK packet ack's the earlier
             * received SYN packet. */
            if (!(SEQ_EQ(TCP_GET_ACK(p), ssn->server.isn + 1))) {
                StreamTcpSetEvent(p, STREAM_4WHS_SYNACK_WITH_WRONG_ACK);
 
                SCLogDebug("ssn %p: 4WHS ACK mismatch, packet ACK %"PRIu32""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_ACK(p), ssn->server.isn + 1);
                return -1;
            }
 
            /* Check if the SYN/ACK packet SEQ's the *FIRST* received SYN
             * packet. */
            if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->client.isn))) {
                StreamTcpSetEvent(p, STREAM_4WHS_SYNACK_WITH_WRONG_SYN);
 
                SCLogDebug("ssn %p: 4WHS SEQ mismatch, packet SEQ %"PRIu32""
                        " != %" PRIu32 " from *first* SYN pkt", ssn,
                        TCP_GET_SEQ(p), ssn->client.isn);
                return -1;
            }
 
 
            /* update state */
            StreamTcpPacketSetState(p, ssn, TCP_SYN_RECV);
            SCLogDebug("ssn %p: =~ 4WHS ssn state is now TCP_SYN_RECV", ssn);
 
            /* sequence number & window */
            ssn->client.isn = TCP_GET_SEQ(p);
            STREAMTCP_SET_RA_BASE_SEQ(&ssn->client, ssn->client.isn);
            ssn->client.next_seq = ssn->client.isn + 1;
 
            ssn->server.window = TCP_GET_WINDOW(p);
            SCLogDebug("ssn %p: 4WHS window %" PRIu32 "", ssn,
                    ssn->client.window);
 
            /* Set the timestamp values used to validate the timestamp of
             * received packets. */
            if ((TCP_HAS_TS(p)) &&
                    (ssn->server.flags & STREAMTCP_STREAM_FLAG_TIMESTAMP))
            {
                ssn->client.last_ts = TCP_GET_TSVAL(p);
                SCLogDebug("ssn %p: 4WHS ssn->client.last_ts %" PRIu32" "
                        "ssn->server.last_ts %" PRIu32"", ssn,
                        ssn->client.last_ts, ssn->server.last_ts);
                ssn->flags |= STREAMTCP_FLAG_TIMESTAMP;
                ssn->client.last_pkt_ts = SCTIME_SECS(p->ts);
                if (ssn->client.last_ts == 0)
                    ssn->client.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
            } else {
                ssn->server.last_ts = 0;
                ssn->client.last_ts = 0;
                ssn->server.flags &= ~STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
            }
 
            ssn->server.last_ack = TCP_GET_ACK(p);
            ssn->client.last_ack = ssn->client.isn + 1;
 
            /** check for the presense of the ws ptr to determine if we
             *  support wscale at all */
            if ((ssn->flags & STREAMTCP_FLAG_SERVER_WSCALE) &&
                    (TCP_HAS_WSCALE(p)))
            {
                ssn->server.wscale = TCP_GET_WSCALE(p);
            } else {
                ssn->server.wscale = 0;
            }
 
            if ((ssn->flags & STREAMTCP_FLAG_CLIENT_SACKOK) &&
                    TCP_GET_SACKOK(p) == 1) {
                ssn->flags |= STREAMTCP_FLAG_SACKOK;
                SCLogDebug("ssn %p: SACK permitted for 4WHS session", ssn);
            }
 
            ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
            ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
            SCLogDebug("ssn %p: 4WHS ssn->client.next_win %" PRIu32 "", ssn,
                    ssn->client.next_win);
            SCLogDebug("ssn %p: 4WHS ssn->server.next_win %" PRIu32 "", ssn,
                    ssn->server.next_win);
            SCLogDebug("ssn %p: 4WHS ssn->client.isn %" PRIu32 ", "
                    "ssn->client.next_seq %" PRIu32 ", "
                    "ssn->client.last_ack %" PRIu32 " "
                    "(ssn->server.last_ack %" PRIu32 ")", ssn,
                    ssn->client.isn, ssn->client.next_seq,
                    ssn->client.last_ack, ssn->server.last_ack);
 
            /* done here */
            return 0;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_IN_WRONG_DIRECTION);
            SCLogDebug("ssn %p: SYN/ACK received in the wrong direction", ssn);
            return -1;
        }
 
        if (!(TCP_HAS_TFO(p) || (ssn->flags & STREAMTCP_FLAG_TCP_FAST_OPEN))) {
            /* Check if the SYN/ACK packet ack's the earlier
             * received SYN packet. */
            if (!(SEQ_EQ(TCP_GET_ACK(p), ssn->client.isn + 1))) {
                StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_WITH_WRONG_ACK);
                SCLogDebug("ssn %p: ACK mismatch, packet ACK %" PRIu32 " != "
                        "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                        ssn->client.isn + 1);
                return -1;
            }
        } else {
            if (!(SEQ_EQ(TCP_GET_ACK(p), ssn->client.next_seq))) {
                StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_WITH_WRONG_ACK);
                SCLogDebug("ssn %p: (TFO) ACK mismatch, packet ACK %" PRIu32 " != "
                        "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                        ssn->client.next_seq);
                return -1;
            }
            SCLogDebug("ssn %p: (TFO) ACK match, packet ACK %" PRIu32 " == "
                    "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                    ssn->client.next_seq);
 
            ssn->flags |= STREAMTCP_FLAG_TCP_FAST_OPEN;
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
        }
        StreamTcp3whsSynAckUpdate(ssn, p, /* no queue override */NULL);
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn %p: SYN packet on state SYN_SENT... resent", ssn);
        if (ssn->flags & STREAMTCP_FLAG_4WHS) {
            SCLogDebug("ssn %p: SYN packet on state SYN_SENT... resent of "
                    "4WHS SYN", ssn);
        }
 
        if (PKT_IS_TOCLIENT(p)) {
            /** a SYN only packet in the opposite direction could be:
             *  http://www.breakingpointsystems.com/community/blog/tcp-
             *  portals-the-three-way-handshake-is-a-lie
             *
             * \todo improve resetting the session */
 
            /* indicate that we're dealing with 4WHS here */
            ssn->flags |= STREAMTCP_FLAG_4WHS;
            SCLogDebug("ssn %p: STREAMTCP_FLAG_4WHS flag set", ssn);
 
            /* set the sequence numbers and window for server
             * We leave the ssn->client.isn in place as we will
             * check the SYN/ACK pkt with that.
             */
            ssn->server.isn = TCP_GET_SEQ(p);
            STREAMTCP_SET_RA_BASE_SEQ(&ssn->server, ssn->server.isn);
            ssn->server.next_seq = ssn->server.isn + 1;
 
            /* Set the stream timestamp value, if packet has timestamp
             * option enabled. */
            if (TCP_HAS_TS(p)) {
                ssn->server.last_ts = TCP_GET_TSVAL(p);
                SCLogDebug("ssn %p: %02x", ssn, ssn->server.last_ts);
 
                if (ssn->server.last_ts == 0)
                    ssn->server.flags |= STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
                ssn->server.last_pkt_ts = SCTIME_SECS(p->ts);
                ssn->server.flags |= STREAMTCP_STREAM_FLAG_TIMESTAMP;
            }
 
            ssn->server.window = TCP_GET_WINDOW(p);
            if (TCP_HAS_WSCALE(p)) {
                ssn->flags |= STREAMTCP_FLAG_SERVER_WSCALE;
                ssn->server.wscale = TCP_GET_WSCALE(p);
            } else {
                ssn->flags &= ~STREAMTCP_FLAG_SERVER_WSCALE;
                ssn->server.wscale = 0;
            }
 
            if (TCP_GET_SACKOK(p) == 1) {
                ssn->flags |= STREAMTCP_FLAG_CLIENT_SACKOK;
            } else {
                ssn->flags &= ~STREAMTCP_FLAG_CLIENT_SACKOK;
            }
 
            SCLogDebug("ssn %p: 4WHS ssn->server.isn %" PRIu32 ", "
                    "ssn->server.next_seq %" PRIu32 ", "
                    "ssn->server.last_ack %"PRIu32"", ssn,
                    ssn->server.isn, ssn->server.next_seq,
                    ssn->server.last_ack);
            SCLogDebug("ssn %p: 4WHS ssn->client.isn %" PRIu32 ", "
                    "ssn->client.next_seq %" PRIu32 ", "
                    "ssn->client.last_ack %"PRIu32"", ssn,
                    ssn->client.isn, ssn->client.next_seq,
                    ssn->client.last_ack);
        } else if (PKT_IS_TOSERVER(p)) {
            /*
             * On retransmitted SYN packets, the timestamp value must be updated,
             * to avoid dropping any SYN+ACK packets that respond to a retransmitted SYN
             * with an updated timestamp in StateSynSentValidateTimestamp.
             */
            if ((ssn->client.flags & STREAMTCP_STREAM_FLAG_TIMESTAMP) && TCP_HAS_TS(p)) {
                uint32_t ts_val = TCP_GET_TSVAL(p);
 
                // Check whether packets have been received in the correct order (only ever update)
                if (ssn->client.last_ts < ts_val) {
                    ssn->client.last_ts = ts_val;
                    ssn->client.last_pkt_ts = SCTIME_SECS(p->ts);
                }
 
                SCLogDebug("ssn %p: Retransmitted SYN. Updated timestamp from packet %" PRIu64, ssn,
                        p->pcap_cnt);
            }
        }
 
        /** \todo check if it's correct or set event */
 
    } else if (p->tcph->th_flags & TH_ACK) {
        /* Handle the asynchronous stream, when we receive a  SYN packet
           and now instead of receiving a SYN/ACK we receive a ACK from the
           same host, which sent the SYN, this suggests the ASYNC streams.*/
        if (stream_config.async_oneside == FALSE)
            return 0;
 
        /* we are in AYNC (one side) mode now. */
 
        /* one side async means we won't see a SYN/ACK, so we can
         * only check the SYN. */
        if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq))) {
            StreamTcpSetEvent(p, STREAM_3WHS_ASYNC_WRONG_SEQ);
 
            SCLogDebug("ssn %p: SEQ mismatch, packet SEQ %" PRIu32 " != "
                    "%" PRIu32 " from stream",ssn, TCP_GET_SEQ(p),
                    ssn->client.next_seq);
            return -1;
        }
 
        ssn->flags |= STREAMTCP_FLAG_ASYNC;
        StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
        SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
        ssn->client.window = TCP_GET_WINDOW(p);
        ssn->client.last_ack = TCP_GET_SEQ(p);
        ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
 
        /* Set the server side parameters */
        ssn->server.isn = TCP_GET_ACK(p) - 1;
        STREAMTCP_SET_RA_BASE_SEQ(&ssn->server, ssn->server.isn);
        ssn->server.next_seq = ssn->server.isn + 1;
        ssn->server.last_ack = ssn->server.next_seq;
        ssn->server.next_win = ssn->server.last_ack;
 
        SCLogDebug("ssn %p: synsent => Asynchronous stream, packet SEQ"
                " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "), "
                "ssn->client.next_seq %" PRIu32 ""
                ,ssn, TCP_GET_SEQ(p), p->payload_len, TCP_GET_SEQ(p)
                + p->payload_len, ssn->client.next_seq);
 
        /* if SYN had wscale, assume it to be supported. Otherwise
         * we know it not to be supported. */
        if (ssn->flags & STREAMTCP_FLAG_SERVER_WSCALE) {
            ssn->client.wscale = TCP_WSCALE_MAX;
        }
 
        /* Set the timestamp values used to validate the timestamp of
         * received packets.*/
        if (TCP_HAS_TS(p) &&
                (ssn->client.flags & STREAMTCP_STREAM_FLAG_TIMESTAMP))
        {
            ssn->flags |= STREAMTCP_FLAG_TIMESTAMP;
            ssn->client.flags &= ~STREAMTCP_STREAM_FLAG_TIMESTAMP;
            ssn->client.last_pkt_ts = SCTIME_SECS(p->ts);
        } else {
            ssn->client.last_ts = 0;
            ssn->client.flags &= ~STREAMTCP_STREAM_FLAG_ZERO_TIMESTAMP;
        }
 
        if (ssn->flags & STREAMTCP_FLAG_CLIENT_SACKOK) {
            ssn->flags |= STREAMTCP_FLAG_SACKOK;
        }
 
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                &ssn->client, p, pq);
 
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_SYN_RECV state. The function handles
 *          SYN, SYN/ACK, ACK, FIN, RST packets and correspondingly changes
 *          the connection state.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 *
 *  \retval  0 ok
 *  \retval -1 error
 */
 
static int StreamTcpPacketStateSynRecv(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn,
        PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        bool reset = true;
        /* After receiveing the RST in SYN_RECV state and if detection
           evasion flags has been set, then the following operating
           systems will not closed the connection. As they consider the
           packet as stray packet and not belonging to the current
           session, for more information check
           http://www.packetstan.com/2010/06/recently-ive-been-on-campaign-to-make.html */
        if (ssn->flags & STREAMTCP_FLAG_DETECTION_EVASION_ATTEMPT) {
            if (PKT_IS_TOSERVER(p)) {
                if ((ssn->server.os_policy == OS_POLICY_LINUX) ||
                        (ssn->server.os_policy == OS_POLICY_OLD_LINUX) ||
                        (ssn->server.os_policy == OS_POLICY_SOLARIS))
                {
                    reset = false;
                    SCLogDebug("Detection evasion has been attempted, so"
                            " not resetting the connection !!");
                }
            } else {
                if ((ssn->client.os_policy == OS_POLICY_LINUX) ||
                        (ssn->client.os_policy == OS_POLICY_OLD_LINUX) ||
                        (ssn->client.os_policy == OS_POLICY_SOLARIS))
                {
                    reset = false;
                    SCLogDebug("Detection evasion has been attempted, so"
                            " not resetting the connection !!");
                }
            }
        }
 
        if (reset) {
            StreamTcpCloseSsnWithReset(p, ssn);
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        /* FIN is handled in the same way as in TCP_ESTABLISHED case */;
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if ((StreamTcpHandleFin(tv, stt, ssn, p, pq)) == -1)
            return -1;
 
    /* SYN/ACK */
    } else if ((p->tcph->th_flags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) {
        SCLogDebug("ssn %p: SYN/ACK packet on state SYN_RECV. resent", ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: SYN/ACK-pkt to server in SYN_RECV state", ssn);
 
            StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_TOSERVER_ON_SYN_RECV);
            return -1;
        }
 
        /* Check if the SYN/ACK packets ACK matches the earlier
         * received SYN/ACK packet. */
        if (!(SEQ_EQ(TCP_GET_ACK(p), ssn->client.last_ack))) {
            SCLogDebug("ssn %p: ACK mismatch, packet ACK %" PRIu32 " != "
                    "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                    ssn->client.isn + 1);
 
            StreamTcpSetEvent(p, STREAM_3WHS_SYNACK_RESEND_WITH_DIFFERENT_ACK);
            return -1;
        }
 
        /* Check if the SYN/ACK packet SEQ the earlier
         * received SYN/ACK packet, server resend with different ISN. */
        if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->server.isn))) {
            SCLogDebug("ssn %p: SEQ mismatch, packet SEQ %" PRIu32 " != "
                    "%" PRIu32 " from stream", ssn, TCP_GET_SEQ(p),
                    ssn->client.isn);
 
            if (StreamTcp3whsQueueSynAck(ssn, p) == -1)
                return -1;
            SCLogDebug("ssn %p: queued different SYN/ACK", ssn);
        }
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn %p: SYN packet on state SYN_RECV... resent", ssn);
 
        if (PKT_IS_TOCLIENT(p)) {
            SCLogDebug("ssn %p: SYN-pkt to client in SYN_RECV state", ssn);
 
            StreamTcpSetEvent(p, STREAM_3WHS_SYN_TOCLIENT_ON_SYN_RECV);
            return -1;
        }
 
        if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->client.isn))) {
            SCLogDebug("ssn %p: SYN with different SEQ on SYN_RECV state", ssn);
 
            StreamTcpSetEvent(p, STREAM_3WHS_SYN_RESEND_DIFF_SEQ_ON_SYN_RECV);
            return -1;
        }
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->queue_len) {
            SCLogDebug("ssn %p: checking ACK against queued SYN/ACKs", ssn);
            TcpStateQueue *q = StreamTcp3whsFindSynAckByAck(ssn, p);
            if (q != NULL) {
                SCLogDebug("ssn %p: here we update state against queued SYN/ACK", ssn);
                StreamTcp3whsSynAckUpdate(ssn, p, /* using queue to update state */q);
            } else {
                SCLogDebug("ssn %p: none found, now checking ACK against original SYN/ACK (state)", ssn);
            }
        }
 
 
        /* If the timestamp option is enabled for both the streams, then
         * validate the received packet timestamp value against the
         * stream->last_ts. If the timestamp is valid then process the
         * packet normally otherwise the drop the packet (RFC 1323)*/
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!(StreamTcpValidateTimestamp(ssn, p))) {
                return -1;
            }
        }
 
        if ((ssn->flags & STREAMTCP_FLAG_4WHS) && PKT_IS_TOCLIENT(p)) {
            SCLogDebug("ssn %p: ACK received on 4WHS session",ssn);
 
            if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq))) {
                SCLogDebug("ssn %p: 4WHS wrong seq nr on packet", ssn);
                StreamTcpSetEvent(p, STREAM_4WHS_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: 4WHS invalid ack nr on packet", ssn);
                StreamTcpSetEvent(p, STREAM_4WHS_INVALID_ACK);
                return -1;
            }
 
            SCLogDebug("4WHS normal pkt");
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
            StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
            SCLogDebug("ssn %p: ssn->client.next_win %" PRIu32 ", "
                    "ssn->client.last_ack %"PRIu32"", ssn,
                    ssn->client.next_win, ssn->client.last_ack);
            return 0;
        }
 
        bool ack_indicates_missed_3whs_ack_packet = false;
        /* Check if the ACK received is in right direction. But when we have
         * picked up a mid stream session after missing the initial SYN pkt,
         * in this case the ACK packet can arrive from either client (normal
         * case) or from server itself (asynchronous streams). Therefore
         *  the check has been avoided in this case */
        if (PKT_IS_TOCLIENT(p)) {
            /* special case, handle 4WHS, so SYN/ACK in the opposite
             * direction */
            if (ssn->flags & STREAMTCP_FLAG_MIDSTREAM_SYNACK) {
                SCLogDebug("ssn %p: ACK received on midstream SYN/ACK "
                        "pickup session",ssn);
                /* fall through */
            } else if (ssn->flags & STREAMTCP_FLAG_TCP_FAST_OPEN) {
                SCLogDebug("ssn %p: ACK received on TFO session",ssn);
                /* fall through */
 
            } else {
                /* if we missed traffic between the S/SA and the current
                 * 'wrong direction' ACK, we could end up here. In IPS
                 * reject it. But in IDS mode we continue.
                 *
                 * IPS rejects as it should see all packets, so pktloss
                 * should lead to retransmissions. As this can also be
                 * pattern for MOTS/MITM injection attacks, we need to be
                 * careful.
                 */
                if (StreamTcpInlineMode()) {
                    if (p->payload_len > 0 &&
                            SEQ_EQ(TCP_GET_ACK(p), ssn->client.last_ack) &&
                            SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq)) {
                        /* packet loss is possible but unlikely here */
                        SCLogDebug("ssn %p: possible data injection", ssn);
                        StreamTcpSetEvent(p, STREAM_3WHS_ACK_DATA_INJECT);
                        return -1;
                    }
 
                    SCLogDebug("ssn %p: ACK received in the wrong direction",
                            ssn);
                    StreamTcpSetEvent(p, STREAM_3WHS_ACK_IN_WRONG_DIR);
                    return -1;
                }
                ack_indicates_missed_3whs_ack_packet = true;
            }
        }
 
        SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ %" PRIu32 ""
                ", ACK %" PRIu32 "", ssn, p->payload_len, TCP_GET_SEQ(p),
                TCP_GET_ACK(p));
 
        /* Check both seq and ack number before accepting the packet and
           changing to ESTABLISHED state */
        if ((SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq)) &&
                SEQ_EQ(TCP_GET_ACK(p), ssn->server.next_seq)) {
            SCLogDebug("normal pkt");
 
            /* process the packet normal, No Async streams :) */
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
            StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
 
            ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
 
            if (ssn->flags & STREAMTCP_FLAG_MIDSTREAM) {
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
                ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
                ssn->server.next_win = ssn->server.last_ack +
                    ssn->server.window;
                if (!(ssn->flags & STREAMTCP_FLAG_MIDSTREAM_SYNACK)) {
                    /* window scaling for midstream pickups, we can't do much
                     * other than assume that it's set to the max value: 14 */
                    ssn->server.wscale = TCP_WSCALE_MAX;
                    ssn->client.wscale = TCP_WSCALE_MAX;
                    ssn->flags |= STREAMTCP_FLAG_SACKOK;
                }
            }
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            /* If asynchronous stream handling is allowed then set the session,
               if packet's seq number is equal the expected seq no.*/
        } else if (stream_config.async_oneside == TRUE &&
                (SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq)))
        {
            /*set the ASYNC flag used to indicate the session as async stream
              and helps in relaxing the windows checks.*/
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
            ssn->server.next_seq += p->payload_len;
            ssn->server.last_ack = TCP_GET_SEQ(p);
 
            ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            ssn->client.last_ack = TCP_GET_ACK(p);
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            if (ssn->flags & STREAMTCP_FLAG_MIDSTREAM) {
                ssn->server.window = TCP_GET_WINDOW(p);
                ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
                /* window scaling for midstream pickups, we can't do much
                 * other than assume that it's set to the max value: 14 */
                ssn->server.wscale = TCP_WSCALE_MAX;
                ssn->client.wscale = TCP_WSCALE_MAX;
                ssn->flags |= STREAMTCP_FLAG_SACKOK;
            }
 
            SCLogDebug("ssn %p: synrecv => Asynchronous stream, packet SEQ"
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "), "
                    "ssn->server.next_seq %" PRIu32
                    , ssn, TCP_GET_SEQ(p), p->payload_len, TCP_GET_SEQ(p)
                    + p->payload_len, ssn->server.next_seq);
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            /* Upon receiving the packet with correct seq number and wrong
               ACK number, it causes the other end to send RST. But some target
               system (Linux & solaris) does not RST the connection, so it is
               likely to avoid the detection */
        } else if (SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq)){
            ssn->flags |= STREAMTCP_FLAG_DETECTION_EVASION_ATTEMPT;
            SCLogDebug("ssn %p: wrong ack nr on packet, possible evasion!!",
                    ssn);
 
            StreamTcpSetEvent(p, STREAM_3WHS_RIGHT_SEQ_WRONG_ACK_EVASION);
            return -1;
 
            /* SYN/ACK followed by more TOCLIENT suggesting packet loss */
        } else if (PKT_IS_TOCLIENT(p) && !StreamTcpInlineMode() &&
                   SEQ_GT(TCP_GET_SEQ(p), ssn->client.next_seq) &&
                   SEQ_GT(TCP_GET_ACK(p), ssn->client.last_ack)) {
            SCLogDebug("ssn %p: ACK for missing data", ssn);
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            ssn->server.next_seq = TCP_GET_SEQ(p) + p->payload_len;
            SCLogDebug("ssn %p: ACK for missing data: ssn->server.next_seq %u", ssn,
                    ssn->server.next_seq);
            ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
 
            ssn->client.next_win = ssn->client.last_ack + ssn->client.window;
 
            ssn->client.window = TCP_GET_WINDOW(p);
            ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->server, p, pq);
 
            /* if we get a packet with a proper ack, but a seq that is beyond
             * next_seq but in-window, we probably missed some packets */
        } else if (SEQ_GT(TCP_GET_SEQ(p), ssn->client.next_seq) &&
                   SEQ_LEQ(TCP_GET_SEQ(p), ssn->client.next_win) &&
                   SEQ_EQ(TCP_GET_ACK(p), ssn->server.next_seq)) {
            SCLogDebug("ssn %p: ACK for missing data", ssn);
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            ssn->client.next_seq = TCP_GET_SEQ(p) + p->payload_len;
            SCLogDebug("ssn %p: ACK for missing data: ssn->client.next_seq %u", ssn, ssn->client.next_seq);
            ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
 
            ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
 
            if (ssn->flags & STREAMTCP_FLAG_MIDSTREAM) {
                ssn->client.window = TCP_GET_WINDOW(p);
                ssn->server.next_win = ssn->server.last_ack +
                    ssn->server.window;
                /* window scaling for midstream pickups, we can't do much
                 * other than assume that it's set to the max value: 14 */
                ssn->server.wscale = TCP_WSCALE_MAX;
                ssn->client.wscale = TCP_WSCALE_MAX;
                ssn->flags |= STREAMTCP_FLAG_SACKOK;
            }
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
        /* toclient packet: after having missed the 3whs's final ACK */
        } else if ((ack_indicates_missed_3whs_ack_packet ||
                           (ssn->flags & STREAMTCP_FLAG_TCP_FAST_OPEN)) &&
                   SEQ_EQ(TCP_GET_ACK(p), ssn->client.last_ack) &&
                   SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq)) {
            if (ack_indicates_missed_3whs_ack_packet) {
                SCLogDebug("ssn %p: packet fits perfectly after a missed 3whs-ACK", ssn);
            } else {
                SCLogDebug("ssn %p: (TFO) expected packet fits perfectly after SYN/ACK", ssn);
            }
 
            StreamTcpUpdateNextSeq(ssn, &ssn->server, (TCP_GET_SEQ(p) + p->payload_len));
 
            ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
 
            StreamTcpPacketSetState(p, ssn, TCP_ESTABLISHED);
            SCLogDebug("ssn %p: =~ ssn state is now TCP_ESTABLISHED", ssn);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
        } else {
            SCLogDebug("ssn %p: wrong seq nr on packet", ssn);
 
            StreamTcpSetEvent(p, STREAM_3WHS_WRONG_SEQ_WRONG_ACK);
            return -1;
        }
 
        SCLogDebug("ssn %p: ssn->server.next_win %" PRIu32 ", "
                "ssn->server.last_ack %"PRIu32"", ssn,
                ssn->server.next_win, ssn->server.last_ack);
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_ESTABLISHED state packets, which are
 *          sent by the client to server. The function handles
 *          ACK packets and call StreamTcpReassembleHandleSegment() to handle
 *          the reassembly.
 *
 *  Timestamp has already been checked at this point.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity etc.
 *  \param  ssn     Pointer to the current TCP session
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
static int HandleEstablishedPacketToServer(ThreadVars *tv, TcpSession *ssn, Packet *p,
                        StreamTcpThread *stt, PacketQueueNoLock *pq)
{
    SCLogDebug("ssn %p: =+ pkt (%" PRIu32 ") is to server: SEQ %" PRIu32 ","
               "ACK %" PRIu32 ", WIN %"PRIu16"", ssn, p->payload_len,
                TCP_GET_SEQ(p), TCP_GET_ACK(p), TCP_GET_WINDOW(p));
 
    if (StreamTcpValidateAck(ssn, &(ssn->server), p) == -1) {
        SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
        StreamTcpSetEvent(p, STREAM_EST_INVALID_ACK);
        return -1;
    }
 
    /* check for Keep Alive */
    if ((p->payload_len == 0 || p->payload_len == 1) &&
            (TCP_GET_SEQ(p) == (ssn->client.next_seq - 1))) {
        SCLogDebug("ssn %p: pkt is keep alive", ssn);
 
    /* normal pkt */
    } else if (!(SEQ_GEQ((TCP_GET_SEQ(p)+p->payload_len), ssn->client.last_ack))) {
        if (ssn->flags & STREAMTCP_FLAG_ASYNC) {
            SCLogDebug("ssn %p: server => Asynchrouns stream, packet SEQ"
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "),"
                    " ssn->client.last_ack %" PRIu32 ", ssn->client.next_win"
                    "%" PRIu32"(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                    p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                    ssn->client.last_ack, ssn->client.next_win,
                    TCP_GET_SEQ(p) + p->payload_len - ssn->client.next_win);
 
            /* update the last_ack to current seq number as the session is
             * async and other stream is not updating it anymore :( */
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_SEQ(p));
 
        } else if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p)) &&
                (stream_config.async_oneside == TRUE) &&
                (ssn->flags & STREAMTCP_FLAG_MIDSTREAM)) {
            SCLogDebug("ssn %p: server => Asynchronous stream, packet SEQ."
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "), "
                    "ssn->client.last_ack %" PRIu32 ", ssn->client.next_win "
                    "%" PRIu32 "(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                    p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                    ssn->client.last_ack, ssn->client.next_win,
                    TCP_GET_SEQ(p) + p->payload_len - ssn->client.next_win);
 
            /* it seems we missed SYN and SYN/ACK packets of this session.
             * Update the last_ack to current seq number as the session
             * is async and other stream is not updating it anymore :( */
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_SEQ(p));
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
 
        } else if (SEQ_EQ(ssn->client.last_ack, (ssn->client.isn + 1)) &&
                (stream_config.async_oneside == TRUE) &&
                (ssn->flags & STREAMTCP_FLAG_MIDSTREAM)) {
            SCLogDebug("ssn %p: server => Asynchronous stream, packet SEQ"
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "), "
                    "ssn->client.last_ack %" PRIu32 ", ssn->client.next_win "
                    "%" PRIu32 "(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                    p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                    ssn->client.last_ack, ssn->client.next_win,
                    TCP_GET_SEQ(p) + p->payload_len - ssn->client.next_win);
 
            /* it seems we missed SYN and SYN/ACK packets of this session.
             * Update the last_ack to current seq number as the session
             * is async and other stream is not updating it anymore :(*/
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_SEQ(p));
            ssn->flags |= STREAMTCP_FLAG_ASYNC;
 
        /* if last ack is beyond next_seq, we have accepted ack's for missing data.
         * In this case we do accept the data before last_ack if it is (partly)
         * beyond next seq */
        } else if (SEQ_GT(ssn->client.last_ack, ssn->client.next_seq) &&
                   SEQ_GT((TCP_GET_SEQ(p)+p->payload_len),ssn->client.next_seq))
        {
            SCLogDebug("ssn %p: PKT SEQ %"PRIu32" payload_len %"PRIu16
                    " before last_ack %"PRIu32", after next_seq %"PRIu32":"
                    " acked data that we haven't seen before",
                    ssn, TCP_GET_SEQ(p), p->payload_len, ssn->client.last_ack, ssn->client.next_seq);
            if (SEQ_EQ(TCP_GET_SEQ(p),ssn->client.next_seq)) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            }
        } else {
            SCLogDebug("ssn %p: server => SEQ before last_ack, packet SEQ"
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "), "
                    "ssn->client.last_ack %" PRIu32 ", ssn->client.next_win "
                    "%" PRIu32 "(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                    p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                    ssn->client.last_ack, ssn->client.next_win,
                    TCP_GET_SEQ(p) + p->payload_len - ssn->client.next_win);
 
            SCLogDebug("ssn %p: rejecting because pkt before last_ack", ssn);
            StreamTcpSetEvent(p, STREAM_EST_PKT_BEFORE_LAST_ACK);
            return -1;
        }
    }
 
    int zerowindowprobe = 0;
    /* zero window probe */
    if (p->payload_len == 1 && TCP_GET_SEQ(p) == ssn->client.next_seq && ssn->client.window == 0) {
        SCLogDebug("ssn %p: zero window probe", ssn);
        zerowindowprobe = 1;
 
    /* expected packet */
    } else if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
        StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
 
    /* not completely as expected, but valid */
    } else if (SEQ_LT(TCP_GET_SEQ(p),ssn->client.next_seq) &&
               SEQ_GT((TCP_GET_SEQ(p)+p->payload_len), ssn->client.next_seq))
    {
        StreamTcpUpdateNextSeq(ssn, &ssn->client, (TCP_GET_SEQ(p) + p->payload_len));
        SCLogDebug("ssn %p: ssn->client.next_seq %"PRIu32
                   " (started before next_seq, ended after)",
                   ssn, ssn->client.next_seq);
 
    /* if next_seq has fallen behind last_ack, we got some catching up to do */
    } else if (SEQ_LT(ssn->client.next_seq, ssn->client.last_ack)) {
        StreamTcpUpdateNextSeq(ssn, &ssn->client, (TCP_GET_SEQ(p) + p->payload_len));
        SCLogDebug("ssn %p: ssn->client.next_seq %"PRIu32
                   " (next_seq had fallen behind last_ack)",
                   ssn, ssn->client.next_seq);
 
    } else {
        SCLogDebug("ssn %p: no update to ssn->client.next_seq %"PRIu32
                   " SEQ %u SEQ+ %u last_ack %u",
                   ssn, ssn->client.next_seq,
                   TCP_GET_SEQ(p), TCP_GET_SEQ(p)+p->payload_len, ssn->client.last_ack);
    }
 
    /* in window check */
    if (zerowindowprobe) {
        SCLogDebug("ssn %p: zero window probe, skipping oow check", ssn);
    } else if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->client.next_win) ||
            (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
    {
        SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->client.next_win "
                   "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->client.next_win);
 
        ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
        SCLogDebug("ssn %p: ssn->server.window %"PRIu32"", ssn,
                    ssn->server.window);
 
        /* Check if the ACK value is sane and inside the window limit */
        if (p->tcph->th_flags & TH_ACK)
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
        SCLogDebug("ack %u last_ack %u next_seq %u", TCP_GET_ACK(p), ssn->server.last_ack, ssn->server.next_seq);
 
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            StreamTcpHandleTimestamp(ssn, p);
        }
 
        StreamTcpSackUpdatePacket(&ssn->server, p);
 
        /* update next_win */
        StreamTcpUpdateNextWin(ssn, &ssn->server, (ssn->server.last_ack + ssn->server.window));
 
        /* handle data (if any) */
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->client, p, pq);
 
    } else {
        SCLogDebug("ssn %p: toserver => SEQ out of window, packet SEQ "
                "%" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "),"
                "ssn->client.last_ack %" PRIu32 ", ssn->client.next_win "
                "%" PRIu32 "(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                ssn->client.last_ack, ssn->client.next_win,
                (TCP_GET_SEQ(p) + p->payload_len) - ssn->client.next_win);
        SCLogDebug("ssn %p: window %u sacked %u", ssn, ssn->client.window,
                StreamTcpSackedSize(&ssn->client));
        StreamTcpSetEvent(p, STREAM_EST_PACKET_OUT_OF_WINDOW);
        return -1;
    }
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_ESTABLISHED state packets, which are
 *          sent by the server to client. The function handles
 *          ACK packets and call StreamTcpReassembleHandleSegment() to handle
 *          the reassembly
 *
 *  Timestamp has already been checked at this point.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity etc.
 *  \param  ssn     Pointer to the current TCP session
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
static int HandleEstablishedPacketToClient(ThreadVars *tv, TcpSession *ssn, Packet *p,
                        StreamTcpThread *stt, PacketQueueNoLock *pq)
{
    SCLogDebug("ssn %p: =+ pkt (%" PRIu32 ") is to client: SEQ %" PRIu32 ","
               " ACK %" PRIu32 ", WIN %"PRIu16"", ssn, p->payload_len,
                TCP_GET_SEQ(p), TCP_GET_ACK(p), TCP_GET_WINDOW(p));
 
    if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
        SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
        StreamTcpSetEvent(p, STREAM_EST_INVALID_ACK);
        return -1;
    }
 
    /* To get the server window value from the servers packet, when connection
       is picked up as midstream */
    if ((ssn->flags & STREAMTCP_FLAG_MIDSTREAM) &&
            (ssn->flags & STREAMTCP_FLAG_MIDSTREAM_ESTABLISHED))
    {
        ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
        ssn->server.next_win = ssn->server.last_ack + ssn->server.window;
        ssn->flags &= ~STREAMTCP_FLAG_MIDSTREAM_ESTABLISHED;
        SCLogDebug("ssn %p: adjusted midstream ssn->server.next_win to "
                "%" PRIu32 "", ssn, ssn->server.next_win);
    }
 
    /* check for Keep Alive */
    if ((p->payload_len == 0 || p->payload_len == 1) &&
            (TCP_GET_SEQ(p) == (ssn->server.next_seq - 1))) {
        SCLogDebug("ssn %p: pkt is keep alive", ssn);
 
    /* normal pkt */
    } else if (!(SEQ_GEQ((TCP_GET_SEQ(p)+p->payload_len), ssn->server.last_ack))) {
        if (ssn->flags & STREAMTCP_FLAG_ASYNC) {
 
            SCLogDebug("ssn %p: client => Asynchrouns stream, packet SEQ"
                    " %" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "),"
                    " ssn->client.last_ack %" PRIu32 ", ssn->client.next_win"
                    " %"PRIu32"(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                    p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                    ssn->server.last_ack, ssn->server.next_win,
                    TCP_GET_SEQ(p) + p->payload_len - ssn->server.next_win);
 
            ssn->server.last_ack = TCP_GET_SEQ(p);
 
        /* if last ack is beyond next_seq, we have accepted ack's for missing data.
         * In this case we do accept the data before last_ack if it is (partly)
         * beyond next seq */
        } else if (SEQ_GT(ssn->server.last_ack, ssn->server.next_seq) &&
                   SEQ_GT((TCP_GET_SEQ(p)+p->payload_len),ssn->server.next_seq))
        {
            SCLogDebug("ssn %p: PKT SEQ %"PRIu32" payload_len %"PRIu16
                    " before last_ack %"PRIu32", after next_seq %"PRIu32":"
                    " acked data that we haven't seen before",
                    ssn, TCP_GET_SEQ(p), p->payload_len, ssn->server.last_ack, ssn->server.next_seq);
            if (SEQ_EQ(TCP_GET_SEQ(p),ssn->server.next_seq)) {
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            }
        } else {
            SCLogDebug("ssn %p: PKT SEQ %"PRIu32" payload_len %"PRIu16
                    " before last_ack %"PRIu32". next_seq %"PRIu32,
                    ssn, TCP_GET_SEQ(p), p->payload_len, ssn->server.last_ack, ssn->server.next_seq);
            StreamTcpSetEvent(p, STREAM_EST_PKT_BEFORE_LAST_ACK);
            return -1;
        }
    }
 
    int zerowindowprobe = 0;
    /* zero window probe */
    if (p->payload_len == 1 && TCP_GET_SEQ(p) == ssn->server.next_seq && ssn->server.window == 0) {
        SCLogDebug("ssn %p: zero window probe", ssn);
        zerowindowprobe = 1;
 
    /* expected packet */
    } else if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p))) {
        StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
 
    /* not completely as expected, but valid */
    } else if (SEQ_LT(TCP_GET_SEQ(p),ssn->server.next_seq) &&
               SEQ_GT((TCP_GET_SEQ(p)+p->payload_len), ssn->server.next_seq))
    {
        StreamTcpUpdateNextSeq(ssn, &ssn->server, (TCP_GET_SEQ(p) + p->payload_len));
        SCLogDebug("ssn %p: ssn->server.next_seq %" PRIu32
                   " (started before next_seq, ended after)",
                   ssn, ssn->server.next_seq);
 
    /* if next_seq has fallen behind last_ack, we got some catching up to do */
    } else if (SEQ_LT(ssn->server.next_seq, ssn->server.last_ack)) {
        StreamTcpUpdateNextSeq(ssn, &ssn->server, (TCP_GET_SEQ(p) + p->payload_len));
        SCLogDebug("ssn %p: ssn->server.next_seq %"PRIu32
                   " (next_seq had fallen behind last_ack)",
                   ssn, ssn->server.next_seq);
    } else {
        SCLogDebug("ssn %p: no update to ssn->server.next_seq %"PRIu32
                   " SEQ %u SEQ+ %u last_ack %u",
                   ssn, ssn->server.next_seq,
                   TCP_GET_SEQ(p), TCP_GET_SEQ(p)+p->payload_len, ssn->server.last_ack);
    }
 
    if (zerowindowprobe) {
        SCLogDebug("ssn %p: zero window probe, skipping oow check", ssn);
    } else if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->server.next_win) ||
            (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
    {
        SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->server.next_win "
                "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->server.next_win);
        ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
        SCLogDebug("ssn %p: ssn->client.window %"PRIu32"", ssn,
                    ssn->client.window);
 
        if (p->tcph->th_flags & TH_ACK)
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            StreamTcpHandleTimestamp(ssn, p);
        }
 
        StreamTcpSackUpdatePacket(&ssn->client, p);
 
        StreamTcpUpdateNextWin(ssn, &ssn->client, (ssn->client.last_ack + ssn->client.window));
 
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->server, p, pq);
    } else {
        SCLogDebug("ssn %p: client => SEQ out of window, packet SEQ"
                   "%" PRIu32 ", payload size %" PRIu32 " (%" PRIu32 "),"
                   " ssn->server.last_ack %" PRIu32 ", ssn->server.next_win "
                   "%" PRIu32 "(%"PRIu32")", ssn, TCP_GET_SEQ(p),
                   p->payload_len, TCP_GET_SEQ(p) + p->payload_len,
                   ssn->server.last_ack, ssn->server.next_win,
                   TCP_GET_SEQ(p) + p->payload_len - ssn->server.next_win);
        StreamTcpSetEvent(p, STREAM_EST_PACKET_OUT_OF_WINDOW);
        return -1;
    }
    return 0;
}
 
/**
 *  \internal
 *
 *  \brief Find the highest sequence number needed to consider all segments as ACK'd
 *
 *  Used to treat all segments as ACK'd upon receiving a valid RST.
 *
 *  \param stream stream to inspect the segments from
 *  \param seq sequence number to check against
 *
 *  \retval ack highest ack we need to set
 */
static inline uint32_t StreamTcpResetGetMaxAck(TcpStream *stream, uint32_t seq)
{
    uint32_t ack = seq;
 
    if (STREAM_HAS_SEEN_DATA(stream)) {
        const uint32_t tail_seq = STREAM_SEQ_RIGHT_EDGE(stream);
        if (SEQ_GT(tail_seq, ack)) {
            ack = tail_seq;
        }
    }
 
    SCReturnUInt(ack);
}
 
/** \internal
 *  \brief check if a ACK packet is outdated so processing can be fast tracked
 *
 *  Consider a packet outdated ack if:
 *  - state is >= ESTABLISHED
 *  - ACK < last_ACK
 *  - SACK acks nothing new
 *  - packet has no data
 *  - SEQ == next_SEQ
 *  - flags has ACK set but don't contain SYN/FIN/RST
 *
 *  \todo the most likely explanation for this packet is that we already
 *        accepted a "newer" ACK. We will not consider an outdated timestamp
 *        option an issue for this packet, but we should probably still
 *        check if the ts isn't too far off.
 */
static bool StreamTcpPacketIsOutdatedAck(TcpSession *ssn, Packet *p)
{
    if (ssn->state < TCP_ESTABLISHED)
        return false;
    if (p->payload_len != 0)
        return false;
    if ((p->tcph->th_flags & (TH_ACK | TH_SYN | TH_FIN | TH_RST)) != TH_ACK)
        return false;
 
    /* lets see if this is a packet that is entirely eclipsed by earlier ACKs */
    if (PKT_IS_TOSERVER(p)) {
        if (SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq) &&
                SEQ_LT(TCP_GET_ACK(p), ssn->server.last_ack)) {
            if (!TCP_HAS_SACK(p)) {
                SCLogDebug("outdated ACK (no SACK, SEQ %u vs next_seq %u)", TCP_GET_SEQ(p),
                        ssn->client.next_seq);
                return true;
            }
 
            if (StreamTcpSackPacketIsOutdated(&ssn->server, p)) {
                SCLogDebug("outdated ACK (have SACK, SEQ %u vs next_seq %u)", TCP_GET_SEQ(p),
                        ssn->client.next_seq);
                return true;
            }
        }
    } else {
        if (SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq) &&
                SEQ_LT(TCP_GET_ACK(p), ssn->client.last_ack)) {
            if (!TCP_HAS_SACK(p)) {
                SCLogDebug("outdated ACK (no SACK, SEQ %u vs next_seq %u)", TCP_GET_SEQ(p),
                        ssn->client.next_seq);
                return true;
            }
 
            if (StreamTcpSackPacketIsOutdated(&ssn->client, p)) {
                SCLogDebug("outdated ACK (have SACK, SEQ %u vs next_seq %u)", TCP_GET_SEQ(p),
                        ssn->client.next_seq);
                return true;
            }
        }
    }
    return false;
}
 
/** \internal
 *  \brief check if packet is before ack'd windows
 *  If packet is before last ack, we will not accept it
 */
static bool StreamTcpPacketIsSpuriousRetransmission(TcpSession *ssn, Packet *p)
{
    TcpStream *stream;
    if (PKT_IS_TOCLIENT(p)) {
        stream = &ssn->server;
    } else {
        stream = &ssn->client;
    }
    /* take base_seq into account to avoid edge cases where last_ack might be
     * too far ahead during heavy packet loss */
    const uint32_t le = MIN(stream->last_ack, stream->base_seq);
    if (p->payload_len > 0 && (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, le))) {
        SCLogDebug("ssn %p: spurious retransmission; packet entirely before last_ack: SEQ %u(%u) "
                   "last_ack %u",
                ssn, TCP_GET_SEQ(p), TCP_GET_SEQ(p) + p->payload_len, stream->last_ack);
        return true;
    }
    SCLogDebug("ssn %p: NOT spurious retransmission; packet NOT entirely before last_ack: SEQ "
               "%u(%u) last_ack %u, le %u",
            ssn, TCP_GET_SEQ(p), TCP_GET_SEQ(p) + p->payload_len, stream->last_ack, le);
    return false;
}
 
/**
 *  \brief  Function to handle the TCP_ESTABLISHED state. The function handles
 *          ACK, FIN, RST packets and correspondingly changes the connection
 *          state. The function handles the data inside packets and call
 *          StreamTcpReassembleHandleSegment(tv, ) to handle the reassembling.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity etc.
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateEstablished(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        if (PKT_IS_TOSERVER(p)) {
            StreamTcpCloseSsnWithReset(p, ssn);
 
            ssn->server.next_seq = TCP_GET_ACK(p);
            ssn->client.next_seq = TCP_GET_SEQ(p) + p->payload_len;
            SCLogDebug("ssn %p: ssn->server.next_seq %" PRIu32 "", ssn,
                    ssn->server.next_seq);
            ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
 
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
 
            /* don't return packets to pools here just yet, the pseudo
             * packet will take care, otherwise the normal session
             * cleanup. */
        } else {
            StreamTcpCloseSsnWithReset(p, ssn);
 
            ssn->server.next_seq = TCP_GET_SEQ(p) + p->payload_len + 1;
            ssn->client.next_seq = TCP_GET_ACK(p);
 
            SCLogDebug("ssn %p: ssn->server.next_seq %" PRIu32 "", ssn,
                    ssn->server.next_seq);
            ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
 
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
 
            /* don't return packets to pools here just yet, the pseudo
             * packet will take care, otherwise the normal session
             * cleanup. */
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        SCLogDebug("ssn (%p: FIN received SEQ"
                " %" PRIu32 ", last ACK %" PRIu32 ", next win %"PRIu32","
                " win %" PRIu32 "", ssn, ssn->server.next_seq,
                ssn->client.last_ack, ssn->server.next_win,
                ssn->server.window);
 
        if ((StreamTcpHandleFin(tv, stt, ssn, p, pq)) == -1)
            return -1;
 
    /* SYN/ACK */
    } else if ((p->tcph->th_flags & (TH_SYN|TH_ACK)) == (TH_SYN|TH_ACK)) {
        SCLogDebug("ssn %p: SYN/ACK packet on state ESTABLISHED... resent",
                ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: SYN/ACK-pkt to server in ESTABLISHED state", ssn);
 
            StreamTcpSetEvent(p, STREAM_EST_SYNACK_TOSERVER);
            return -1;
        }
 
        /* Check if the SYN/ACK packets ACK matches the earlier
         * received SYN/ACK packet. */
        if (!(SEQ_EQ(TCP_GET_ACK(p), ssn->client.last_ack))) {
            SCLogDebug("ssn %p: ACK mismatch, packet ACK %" PRIu32 " != "
                    "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                    ssn->client.isn + 1);
 
            StreamTcpSetEvent(p, STREAM_EST_SYNACK_RESEND_WITH_DIFFERENT_ACK);
            return -1;
        }
 
        /* Check if the SYN/ACK packet SEQ the earlier
         * received SYN packet. */
        if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->server.isn))) {
            SCLogDebug("ssn %p: SEQ mismatch, packet SEQ %" PRIu32 " != "
                    "%" PRIu32 " from stream", ssn, TCP_GET_ACK(p),
                    ssn->client.isn + 1);
 
            StreamTcpSetEvent(p, STREAM_EST_SYNACK_RESEND_WITH_DIFF_SEQ);
            return -1;
        }
 
        if (ssn->flags & STREAMTCP_FLAG_3WHS_CONFIRMED) {
            /* a resend of a SYN while we are established already -- fishy */
            StreamTcpSetEvent(p, STREAM_EST_SYNACK_RESEND);
            return -1;
        }
 
        SCLogDebug("ssn %p: SYN/ACK packet on state ESTABLISHED... resent. "
                "Likely due server not receiving final ACK in 3whs", ssn);
        return 0;
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn %p: SYN packet on state ESTABLISHED... resent", ssn);
        if (PKT_IS_TOCLIENT(p)) {
            SCLogDebug("ssn %p: SYN-pkt to client in EST state", ssn);
 
            StreamTcpSetEvent(p, STREAM_EST_SYN_TOCLIENT);
            return -1;
        }
 
        if (!(SEQ_EQ(TCP_GET_SEQ(p), ssn->client.isn))) {
            SCLogDebug("ssn %p: SYN with different SEQ on SYN_RECV state", ssn);
 
            StreamTcpSetEvent(p, STREAM_EST_SYN_RESEND_DIFF_SEQ);
            return -1;
        }
 
        /* a resend of a SYN while we are established already -- fishy */
        StreamTcpSetEvent(p, STREAM_EST_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        /* Urgent pointer size can be more than the payload size, as it tells
         * the future coming data from the sender will be handled urgently
         * until data of size equal to urgent offset has been processed
         * (RFC 2147) */
 
        /* If the timestamp option is enabled for both the streams, then
         * validate the received packet timestamp value against the
         * stream->last_ts. If the timestamp is valid then process the
         * packet normally otherwise the drop the packet (RFC 1323) */
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            /* Process the received packet to server */
            HandleEstablishedPacketToServer(tv, ssn, p, stt, pq);
 
            SCLogDebug("ssn %p: next SEQ %" PRIu32 ", last ACK %" PRIu32 ","
                    " next win %" PRIu32 ", win %" PRIu32 "", ssn,
                    ssn->client.next_seq, ssn->server.last_ack
                    ,ssn->client.next_win, ssn->client.window);
 
        } else { /* implied to client */
            if (!(ssn->flags & STREAMTCP_FLAG_3WHS_CONFIRMED)) {
                ssn->flags |= STREAMTCP_FLAG_3WHS_CONFIRMED;
                SCLogDebug("3whs is now confirmed by server");
            }
 
            /* Process the received packet to client */
            HandleEstablishedPacketToClient(tv, ssn, p, stt, pq);
 
            SCLogDebug("ssn %p: next SEQ %" PRIu32 ", last ACK %" PRIu32 ","
                    " next win %" PRIu32 ", win %" PRIu32 "", ssn,
                    ssn->server.next_seq, ssn->client.last_ack,
                    ssn->server.next_win, ssn->server.window);
        }
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the FIN packets for states TCP_SYN_RECV and
 *          TCP_ESTABLISHED and changes to another TCP state as required.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 *
 *  \retval 0 success
 *  \retval -1 something wrong with the packet
 */
 
static int StreamTcpHandleFin(ThreadVars *tv, StreamTcpThread *stt,
                                TcpSession *ssn, Packet *p, PacketQueueNoLock *pq)
{
    if (PKT_IS_TOSERVER(p)) {
        SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ %" PRIu32 ","
                " ACK %" PRIu32 "", ssn, p->payload_len, TCP_GET_SEQ(p),
                TCP_GET_ACK(p));
 
        if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
            SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
            StreamTcpSetEvent(p, STREAM_FIN_INVALID_ACK);
            return -1;
        }
 
        if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq) ||
            SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
        {
            SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 " != "
                    "%" PRIu32 " from stream", ssn, TCP_GET_SEQ(p),
                    ssn->client.next_seq);
 
            StreamTcpSetEvent(p, STREAM_FIN_OUT_OF_WINDOW);
            return -1;
        }
 
        if (p->tcph->th_flags & TH_SYN) {
            SCLogDebug("ssn %p: FIN+SYN", ssn);
            StreamTcpSetEvent(p, STREAM_FIN_SYN);
            return -1;
        }
        StreamTcpPacketSetState(p, ssn, TCP_CLOSE_WAIT);
        SCLogDebug("ssn %p: state changed to TCP_CLOSE_WAIT", ssn);
 
        if (SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq))
            ssn->client.next_seq = TCP_GET_SEQ(p) + p->payload_len;
 
        SCLogDebug("ssn %p: ssn->client.next_seq %" PRIu32 "", ssn,
                    ssn->client.next_seq);
        ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
 
        if (p->tcph->th_flags & TH_ACK)
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            StreamTcpHandleTimestamp(ssn, p);
        }
 
        /* Update the next_seq, in case if we have missed the client packet
           and server has already received and acked it */
        if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
            ssn->server.next_seq = TCP_GET_ACK(p);
 
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->client, p, pq);
 
        SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK %" PRIu32 "",
                ssn, ssn->client.next_seq, ssn->server.last_ack);
    } else { /* implied to client */
        SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ %" PRIu32 ", "
                   "ACK %" PRIu32 "", ssn, p->payload_len, TCP_GET_SEQ(p),
                    TCP_GET_ACK(p));
 
        if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
            SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
            StreamTcpSetEvent(p, STREAM_FIN_INVALID_ACK);
            return -1;
        }
 
        if (SEQ_LT(TCP_GET_SEQ(p), ssn->server.next_seq) ||
                SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window)))
        {
            SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 " != "
                    "%" PRIu32 " from stream (last_ack %u win %u = %u)", ssn, TCP_GET_SEQ(p),
                    ssn->server.next_seq, ssn->server.last_ack, ssn->server.window, (ssn->server.last_ack + ssn->server.window));
 
            StreamTcpSetEvent(p, STREAM_FIN_OUT_OF_WINDOW);
            return -1;
        }
 
        StreamTcpPacketSetState(p, ssn, TCP_FIN_WAIT1);
        SCLogDebug("ssn %p: state changed to TCP_FIN_WAIT1", ssn);
 
        if (SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq))
            ssn->server.next_seq = TCP_GET_SEQ(p) + p->payload_len;
 
        SCLogDebug("ssn %p: ssn->server.next_seq %" PRIu32 "", ssn,
                    ssn->server.next_seq);
        ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
 
        if (p->tcph->th_flags & TH_ACK)
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            StreamTcpHandleTimestamp(ssn, p);
        }
 
        /* Update the next_seq, in case if we have missed the client packet
           and server has already received and acked it */
        if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
            ssn->client.next_seq = TCP_GET_ACK(p);
 
        StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn, &ssn->server, p, pq);
 
        SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK %" PRIu32 "",
                ssn, ssn->server.next_seq, ssn->client.last_ack);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_FIN_WAIT1 state. The function handles
 *          ACK, FIN, RST packets and correspondingly changes the connection
 *          state.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 *
 *  \retval 0 success
 *  \retval -1 something wrong with the packet
 */
 
static int StreamTcpPacketStateFinWait1(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if ((p->tcph->th_flags & (TH_FIN|TH_ACK)) == (TH_FIN|TH_ACK)) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq) ||
                    SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN1_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else { /* implied to client */
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            } else if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p)) &&
                       SEQ_EQ(ssn->client.last_ack, TCP_GET_ACK(p))) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->server.next_seq) ||
                       SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window))) {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->server.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN1_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq) ||
                    SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN1_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_CLOSING);
                SCLogDebug("ssn %p: state changed to TCP_CLOSING", ssn);
 
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else { /* implied to client */
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->server.next_seq) ||
                    SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->server.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN1_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_CLOSING);
                SCLogDebug("ssn %p: state changed to TCP_CLOSING", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on FinWait1", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->client.next_win) ||
                        (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
                {
                    SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->client.next_win "
                            "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->client.next_win);
 
                    if (TCP_GET_SEQ(p) == ssn->client.next_seq) {
                        StreamTcpPacketSetState(p, ssn, TCP_FIN_WAIT2);
                        SCLogDebug("ssn %p: state changed to TCP_FIN_WAIT2", ssn);
                    }
                } else {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->client.next_seq);
 
                    StreamTcpSetEvent(p, STREAM_FIN1_ACK_WRONG_SEQ);
                    return -1;
                }
 
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            }
 
            StreamTcpSackUpdatePacket(&ssn->server, p);
 
            /* update next_win */
            StreamTcpUpdateNextWin(ssn, &ssn->server, (ssn->server.last_ack + ssn->server.window));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
 
        } else { /* implied to client */
 
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN1_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->server.next_win) ||
                        (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
                {
                    SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->server.next_win "
                            "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->server.next_win);
 
                    if (TCP_GET_SEQ(p) == ssn->server.next_seq) {
                        StreamTcpPacketSetState(p, ssn, TCP_FIN_WAIT2);
                        SCLogDebug("ssn %p: state changed to TCP_FIN_WAIT2", ssn);
                    }
                } else {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->server.next_seq);
                    StreamTcpSetEvent(p, STREAM_FIN1_ACK_WRONG_SEQ);
                    return -1;
                }
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            }
 
            StreamTcpSackUpdatePacket(&ssn->client, p);
 
            /* update next_win */
            StreamTcpUpdateNextWin(ssn, &ssn->client, (ssn->client.last_ack + ssn->client.window));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
    } else {
        SCLogDebug("ssn (%p): default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_FIN_WAIT2 state. The function handles
 *          ACK, RST, FIN packets and correspondingly changes the connection
 *          state.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateFinWait2(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (SEQ_EQ(TCP_GET_SEQ(p), ssn->client.next_seq - 1) &&
                SEQ_EQ(TCP_GET_ACK(p), ssn->server.last_ack)) {
                SCLogDebug("ssn %p: retransmission", ssn);
                retransmission = 1;
            } else if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq) ||
                    SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ "
                        "%" PRIu32 " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN2_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN2_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
                    StreamTcpUpdateNextSeq(
                            ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
                }
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else { /* implied to client */
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (SEQ_EQ(TCP_GET_SEQ(p), ssn->server.next_seq - 1) &&
                SEQ_EQ(TCP_GET_ACK(p), ssn->client.last_ack)) {
                SCLogDebug("ssn %p: retransmission", ssn);
                retransmission = 1;
            } else if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (SEQ_LT(TCP_GET_SEQ(p), ssn->server.next_seq) ||
                    SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ "
                        "%" PRIu32 " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->server.next_seq);
                StreamTcpSetEvent(p, STREAM_FIN2_FIN_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN2_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on FinWait2", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN2_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->client.next_win) ||
                        (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
                {
                    SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->client.next_win "
                            "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->client.next_win);
 
                } else {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->client.next_seq);
                    StreamTcpSetEvent(p, STREAM_FIN2_ACK_WRONG_SEQ);
                    return -1;
                }
 
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            if (SEQ_EQ(ssn->client.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
            }
 
            StreamTcpSackUpdatePacket(&ssn->server, p);
 
            /* update next_win */
            StreamTcpUpdateNextWin(ssn, &ssn->server, (ssn->server.last_ack + ssn->server.window));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else { /* implied to client */
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
 
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_FIN2_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                if (SEQ_LEQ(TCP_GET_SEQ(p) + p->payload_len, ssn->server.next_win) ||
                        (ssn->flags & (STREAMTCP_FLAG_MIDSTREAM|STREAMTCP_FLAG_ASYNC)))
                {
                    SCLogDebug("ssn %p: seq %"PRIu32" in window, ssn->server.next_win "
                            "%" PRIu32 "", ssn, TCP_GET_SEQ(p), ssn->server.next_win);
                } else {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->server.next_seq);
                    StreamTcpSetEvent(p, STREAM_FIN2_ACK_WRONG_SEQ);
                    return -1;
                }
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            if (SEQ_EQ(ssn->server.next_seq, TCP_GET_SEQ(p))) {
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
            }
 
            StreamTcpSackUpdatePacket(&ssn->client, p);
 
            /* update next_win */
            StreamTcpUpdateNextWin(ssn, &ssn->client, (ssn->client.last_ack + ssn->client.window));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
 
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_CLOSING state. Upon arrival of ACK
 *          the connection goes to TCP_TIME_WAIT state. The state has been
 *          reached as both end application has been closed.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateClosing(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on Closing", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (TCP_GET_SEQ(p) != ssn->client.next_seq) {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_CLOSING_ACK_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSING_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else { /* implied to client */
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (TCP_GET_SEQ(p) != ssn->server.next_seq) {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->server.next_seq);
                StreamTcpSetEvent(p, STREAM_CLOSING_ACK_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSING_INVALID_ACK);
                return -1;
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_TIME_WAIT);
                SCLogDebug("ssn %p: state changed to TCP_TIME_WAIT", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("StreamTcpPacketStateClosing (%p): =+ next SEQ "
                    "%" PRIu32 ", last ACK %" PRIu32 "", ssn,
                    ssn->server.next_seq, ssn->client.last_ack);
        }
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_CLOSE_WAIT state. Upon arrival of FIN
 *          packet from server the connection goes to TCP_LAST_ACK state.
 *          The state is possible only for server host.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateCloseWait(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    SCEnter();
 
    if (ssn == NULL) {
        SCReturnInt(-1);
    }
 
    if (PKT_IS_TOCLIENT(p)) {
        SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                TCP_GET_SEQ(p), TCP_GET_ACK(p));
    } else {
        SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                TCP_GET_SEQ(p), TCP_GET_ACK(p));
    }
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                SCReturnInt(-1);
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (!retransmission) {
                if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq) ||
                        SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
                {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->client.next_seq);
                    StreamTcpSetEvent(p, STREAM_CLOSEWAIT_FIN_OUT_OF_WINDOW);
                    SCReturnInt(-1);
                }
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            /* don't update to LAST_ACK here as we want a toclient FIN for that */
 
            if (!retransmission)
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (!retransmission) {
                if (SEQ_LT(TCP_GET_SEQ(p), ssn->server.next_seq) ||
                        SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window)))
                {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->server.next_seq);
                    StreamTcpSetEvent(p, STREAM_CLOSEWAIT_FIN_OUT_OF_WINDOW);
                    SCReturnInt(-1);
                }
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_LAST_ACK);
                SCLogDebug("ssn %p: state changed to TCP_LAST_ACK", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            if (p->tcph->th_flags & TH_ACK)
                StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on CloseWait", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        SCReturnInt(-1);
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                SCReturnInt(-1);
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (p->payload_len > 0 && (SEQ_LEQ((TCP_GET_SEQ(p) + p->payload_len), ssn->client.last_ack))) {
                SCLogDebug("ssn %p: -> retransmission", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_PKT_BEFORE_LAST_ACK);
                SCReturnInt(-1);
 
            } else if (SEQ_GT(TCP_GET_SEQ(p), (ssn->client.last_ack + ssn->client.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_ACK_OUT_OF_WINDOW);
                SCReturnInt(-1);
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(TCP_GET_SEQ(p),ssn->client.next_seq))
                StreamTcpUpdateNextSeq(ssn, &ssn->client, (ssn->client.next_seq + p->payload_len));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (p->payload_len > 0 && (SEQ_LEQ((TCP_GET_SEQ(p) + p->payload_len), ssn->server.last_ack))) {
                SCLogDebug("ssn %p: -> retransmission", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_PKT_BEFORE_LAST_ACK);
                SCReturnInt(-1);
 
            } else if (SEQ_GT(TCP_GET_SEQ(p), (ssn->server.last_ack + ssn->server.window)))
            {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->server.next_seq);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_ACK_OUT_OF_WINDOW);
                SCReturnInt(-1);
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_CLOSEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            if (SEQ_EQ(TCP_GET_SEQ(p),ssn->server.next_seq))
                StreamTcpUpdateNextSeq(ssn, &ssn->server, (ssn->server.next_seq + p->payload_len));
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
 
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
    SCReturnInt(0);
}
 
/**
 *  \brief  Function to handle the TCP_LAST_ACK state. Upon arrival of ACK
 *          the connection goes to TCP_CLOSED state and stream memory is
 *          returned back to pool. The state is possible only for server host.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateLastAck(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        /** \todo */
        SCLogDebug("ssn (%p): FIN pkt on LastAck", ssn);
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on LastAck", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
 
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_LASTACK_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                if (SEQ_LT(TCP_GET_SEQ(p), ssn->client.next_seq)) {
                    SCLogDebug("ssn %p: not updating state as packet is before next_seq", ssn);
                } else if (TCP_GET_SEQ(p) != ssn->client.next_seq && TCP_GET_SEQ(p) != ssn->client.next_seq + 1) {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->client.next_seq);
                    StreamTcpSetEvent(p, STREAM_LASTACK_ACK_WRONG_SEQ);
                    return -1;
                } else {
                    StreamTcpPacketSetState(p, ssn, TCP_CLOSED);
                    SCLogDebug("ssn %p: state changed to TCP_CLOSED", ssn);
 
                }
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        }
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
/**
 *  \brief  Function to handle the TCP_TIME_WAIT state. Upon arrival of ACK
 *          the connection goes to TCP_CLOSED state and stream memory is
 *          returned back to pool.
 *
 *  \param  tv      Thread Variable containing  input/output queue, cpu affinity
 *  \param  p       Packet which has to be handled in this TCP state.
 *  \param  stt     Strean Thread module registered to handle the stream handling
 */
 
static int StreamTcpPacketStateTimeWait(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        if (!StreamTcpValidateRst(ssn, p))
            return -1;
 
        StreamTcpCloseSsnWithReset(p, ssn);
 
        if (PKT_IS_TOSERVER(p)) {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->server, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->server,
                        StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->client,
                    StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
        } else {
            if ((p->tcph->th_flags & TH_ACK) && StreamTcpValidateAck(ssn, &ssn->client, p) == 0)
                StreamTcpUpdateLastAck(ssn, &ssn->client,
                        StreamTcpResetGetMaxAck(&ssn->client, TCP_GET_ACK(p)));
 
            StreamTcpUpdateLastAck(ssn, &ssn->server,
                    StreamTcpResetGetMaxAck(&ssn->server, TCP_GET_SEQ(p)));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
        }
 
    } else if (p->tcph->th_flags & TH_FIN) {
        /** \todo */
 
    } else if (p->tcph->th_flags & TH_SYN) {
        SCLogDebug("ssn (%p): SYN pkt on TimeWait", ssn);
        StreamTcpSetEvent(p, STREAM_SHUTDOWN_SYN_RESEND);
        return -1;
 
    } else if (p->tcph->th_flags & TH_ACK) {
        if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
            if (!StreamTcpValidateTimestamp(ssn, p))
                return -1;
        }
 
        if (PKT_IS_TOSERVER(p)) {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to server: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->client, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
 
            } else if (TCP_GET_SEQ(p) != ssn->client.next_seq && TCP_GET_SEQ(p) != ssn->client.next_seq+1) {
                SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                        " != %" PRIu32 " from stream", ssn,
                        TCP_GET_SEQ(p), ssn->client.next_seq);
                StreamTcpSetEvent(p, STREAM_TIMEWAIT_ACK_WRONG_SEQ);
                return -1;
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->server, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_TIMEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_CLOSED);
                SCLogDebug("ssn %p: state changed to TCP_CLOSED", ssn);
 
                ssn->server.window = TCP_GET_WINDOW(p) << ssn->server.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->server, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->server.next_seq, TCP_GET_ACK(p)))
                ssn->server.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->client, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->client.next_seq,
                    ssn->server.last_ack);
        } else {
            SCLogDebug("ssn %p: pkt (%" PRIu32 ") is to client: SEQ "
                    "%" PRIu32 ", ACK %" PRIu32 "", ssn, p->payload_len,
                    TCP_GET_SEQ(p), TCP_GET_ACK(p));
            int retransmission = 0;
            if (StreamTcpPacketIsRetransmission(&ssn->server, p)) {
                SCLogDebug("ssn %p: packet is retransmission", ssn);
                retransmission = 1;
            } else if (TCP_GET_SEQ(p) != ssn->server.next_seq && TCP_GET_SEQ(p) != ssn->server.next_seq+1) {
                if (p->payload_len > 0 && TCP_GET_SEQ(p) == ssn->server.last_ack) {
                    SCLogDebug("ssn %p: -> retransmission", ssn);
                    SCReturnInt(0);
                } else {
                    SCLogDebug("ssn %p: -> SEQ mismatch, packet SEQ %" PRIu32 ""
                            " != %" PRIu32 " from stream", ssn,
                            TCP_GET_SEQ(p), ssn->server.next_seq);
                    StreamTcpSetEvent(p, STREAM_TIMEWAIT_ACK_WRONG_SEQ);
                    return -1;
                }
            }
 
            if (StreamTcpValidateAck(ssn, &ssn->client, p) == -1) {
                SCLogDebug("ssn %p: rejecting because of invalid ack value", ssn);
                StreamTcpSetEvent(p, STREAM_TIMEWAIT_INVALID_ACK);
                SCReturnInt(-1);
            }
 
            if (!retransmission) {
                StreamTcpPacketSetState(p, ssn, TCP_CLOSED);
                SCLogDebug("ssn %p: state changed to TCP_CLOSED", ssn);
 
                ssn->client.window = TCP_GET_WINDOW(p) << ssn->client.wscale;
            }
 
            StreamTcpUpdateLastAck(ssn, &ssn->client, TCP_GET_ACK(p));
 
            if (ssn->flags & STREAMTCP_FLAG_TIMESTAMP) {
                StreamTcpHandleTimestamp(ssn, p);
            }
 
            /* Update the next_seq, in case if we have missed the client
               packet and server has already received and acked it */
            if (SEQ_LT(ssn->client.next_seq, TCP_GET_ACK(p)))
                ssn->client.next_seq = TCP_GET_ACK(p);
 
            StreamTcpReassembleHandleSegment(tv, stt->ra_ctx, ssn,
                    &ssn->server, p, pq);
            SCLogDebug("ssn %p: =+ next SEQ %" PRIu32 ", last ACK "
                    "%" PRIu32 "", ssn, ssn->server.next_seq,
                    ssn->client.last_ack);
        }
 
    } else {
        SCLogDebug("ssn %p: default case", ssn);
    }
 
    return 0;
}
 
static int StreamTcpPacketStateClosed(ThreadVars *tv, Packet *p,
        StreamTcpThread *stt, TcpSession *ssn, PacketQueueNoLock *pq)
{
    if (ssn == NULL)
        return -1;
 
    if (p->tcph->th_flags & TH_RST) {
        SCLogDebug("RST on closed state");
        return 0;
    }
 
    TcpStream *stream = NULL, *ostream = NULL;
    if (PKT_IS_TOSERVER(p)) {
        stream = &ssn->client;
        ostream = &ssn->server;
    } else {
        stream = &ssn->server;
        ostream = &ssn->client;
    }
 
    SCLogDebug("stream %s ostream %s",
            stream->flags & STREAMTCP_STREAM_FLAG_RST_RECV?"true":"false",
            ostream->flags & STREAMTCP_STREAM_FLAG_RST_RECV ? "true":"false");
 
    /* if we've seen a RST on our direction, but not on the other
     * see if we perhaps need to continue processing anyway. */
    if ((stream->flags & STREAMTCP_STREAM_FLAG_RST_RECV) == 0) {
        if (ostream->flags & STREAMTCP_STREAM_FLAG_RST_RECV) {
            if (StreamTcpStateDispatch(tv, p, stt, ssn, &stt->pseudo_queue, ssn->pstate) < 0)
                return -1;
            /* if state is still "closed", it wasn't updated by our dispatch. */
            if (ssn->state == TCP_CLOSED)
                ssn->state = ssn->pstate;
        }
    }
    return 0;
}
 
static void StreamTcpPacketCheckPostRst(TcpSession *ssn, Packet *p)
{
    if (p->flags & PKT_PSEUDO_S