suricata
decode-ipv4.h
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1 /* Copyright (C) 2007-2024 Open Information Security Foundation
2  *
3  * You can copy, redistribute or modify this Program under the terms of
4  * the GNU General Public License version 2 as published by the Free
5  * Software Foundation.
6  *
7  * This program is distributed in the hope that it will be useful,
8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10  * GNU General Public License for more details.
11  *
12  * You should have received a copy of the GNU General Public License
13  * version 2 along with this program; if not, write to the Free Software
14  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
15  * 02110-1301, USA.
16  */
17 
18 /**
19  * \file
20  *
21  * \author Victor Julien <victor@inliniac.net>
22  * \author Brian Rectanus <brectanu@gmail.com>
23  */
24 
25 #ifndef SURICATA_DECODE_IPV4_H
26 #define SURICATA_DECODE_IPV4_H
27 
28 #define IPV4_HEADER_LEN 20 /**< Header length */
29 #define IPV4_OPTMAX 40 /**< Max options length */
30 #define IPV4_MAXPACKET_LEN 65535 /**< Maximum packet size */
31 
32 /** IP Option Types */
33 #define IPV4_OPT_EOL 0x00 /**< Option: End of List */
34 #define IPV4_OPT_NOP 0x01 /**< Option: No op */
35 #define IPV4_OPT_RR 0x07 /**< Option: Record Route */
36 #define IPV4_OPT_QS 0x19 /**< Option: Quick Start */
37 #define IPV4_OPT_TS 0x44 /**< Option: Timestamp */
38 #define IPV4_OPT_SEC 0x82 /**< Option: Security */
39 #define IPV4_OPT_LSRR 0x83 /**< Option: Loose Source Route */
40 #define IPV4_OPT_ESEC 0x85 /**< Option: Extended Security */
41 #define IPV4_OPT_CIPSO 0x86 /**< Option: Commercial IP Security */
42 #define IPV4_OPT_SID 0x88 /**< Option: Stream Identifier */
43 #define IPV4_OPT_SSRR 0x89 /**< Option: Strict Source Route */
44 #define IPV4_OPT_RTRALT 0x94 /**< Option: Router Alert */
45 
46 /** IP Option Lengths (fixed) */
47 #define IPV4_OPT_SID_LEN 4 /**< SID Option Fixed Length */
48 #define IPV4_OPT_RTRALT_LEN 4 /**< RTRALT Option Fixed Length */
49 
50 /** IP Option Lengths (variable) */
51 #define IPV4_OPT_SEC_MIN 3 /**< SEC, ESEC Option Min Length */
52 #define IPV4_OPT_ROUTE_MIN 3 /**< RR, SRR, LTRR Option Min Length */
53 #define IPV4_OPT_QS_MIN 8 /**< QS Option Min Length */
54 #define IPV4_OPT_TS_MIN 5 /**< TS Option Min Length */
55 #define IPV4_OPT_CIPSO_MIN 10 /**< CIPSO Option Min Length */
56 
57 /** IP Option fields */
58 #define IPV4_OPTS ip4vars.ip_opts
59 #define IPV4_OPTS_CNT ip4vars.ip_opt_cnt
60 
61 typedef struct IPV4Opt_ {
62  /** \todo We may want to break type up into its 3 fields
63  * as the reassembler may want to know which options
64  * must be copied to each fragment.
65  */
66  uint8_t type; /**< option type */
67  uint8_t len; /**< option length (type+len+data) */
68  const uint8_t *data; /**< option data */
69 } IPV4Opt;
70 
71 typedef struct IPV4Hdr_
72 {
73  uint8_t ip_verhl; /**< version & header length */
74  uint8_t ip_tos; /**< type of service */
75  uint16_t ip_len; /**< length */
76  uint16_t ip_id; /**< id */
77  uint16_t ip_off; /**< frag offset */
78  uint8_t ip_ttl; /**< time to live */
79  uint8_t ip_proto; /**< protocol (tcp, udp, etc) */
80  uint16_t ip_csum; /**< checksum */
81  union {
82  struct {
83  struct in_addr ip_src;/**< source address */
84  struct in_addr ip_dst;/**< destination address */
85  } ip4_un1;
86  uint16_t ip_addrs[4];
87  } ip4_hdrun1;
88 } IPV4Hdr;
89 
90 
91 #define s_ip_src ip4_hdrun1.ip4_un1.ip_src
92 #define s_ip_dst ip4_hdrun1.ip4_un1.ip_dst
93 #define s_ip_addrs ip4_hdrun1.ip_addrs
94 
95 #define IPV4_GET_RAW_VER(ip4h) (((ip4h)->ip_verhl & 0xf0) >> 4)
96 #define IPV4_GET_RAW_HLEN(ip4h) (uint8_t)(((ip4h)->ip_verhl & (uint8_t)0x0f) << (uint8_t)2)
97 #define IPV4_GET_RAW_IPTOS(ip4h) ((ip4h)->ip_tos)
98 #define IPV4_GET_RAW_IPLEN(ip4h) (SCNtohs((ip4h)->ip_len))
99 #define IPV4_GET_RAW_IPID(ip4h) (SCNtohs((ip4h)->ip_id))
100 #define IPV4_GET_RAW_IPOFFSET(ip4h) SCNtohs((ip4h)->ip_off)
101 #define IPV4_GET_RAW_FRAGOFFSET(ip4h) (IPV4_GET_RAW_IPOFFSET((ip4h)) & 0x1fff)
102 #define IPV4_GET_RAW_IPTTL(ip4h) ((ip4h)->ip_ttl)
103 #define IPV4_GET_RAW_IPPROTO(ip4h) ((ip4h)->ip_proto)
104 #define IPV4_GET_RAW_IPSRC(ip4h) ((ip4h)->s_ip_src)
105 #define IPV4_GET_RAW_IPDST(ip4h) ((ip4h)->s_ip_dst)
106 
107 /** return the raw (directly from the header) src ip as uint32_t */
108 #define IPV4_GET_RAW_IPSRC_U32(ip4h) (uint32_t)((ip4h)->s_ip_src.s_addr)
109 /** return the raw (directly from the header) dst ip as uint32_t */
110 #define IPV4_GET_RAW_IPDST_U32(ip4h) (uint32_t)((ip4h)->s_ip_dst.s_addr)
111 
112 #define IPV4_GET_RAW_FLAG_MF(ip4h) ((IPV4_GET_RAW_IPOFFSET((ip4h)) & 0x2000) != 0)
113 #define IPV4_GET_RAW_FLAG_DF(ip4h) ((IPV4_GET_RAW_IPOFFSET((ip4h)) & 0x4000) != 0)
114 #define IPV4_GET_RAW_FLAG_RF(ip4h) ((IPV4_GET_RAW_IPOFFSET((ip4h)) & 0x8000) != 0)
115 
116 #define IPV4_OPT_FLAG_EOL BIT_U16(1)
117 #define IPV4_OPT_FLAG_NOP BIT_U16(2)
118 #define IPV4_OPT_FLAG_RR BIT_U16(3)
119 #define IPV4_OPT_FLAG_TS BIT_U16(4)
120 #define IPV4_OPT_FLAG_QS BIT_U16(5)
121 #define IPV4_OPT_FLAG_LSRR BIT_U16(6)
122 #define IPV4_OPT_FLAG_SSRR BIT_U16(7)
123 #define IPV4_OPT_FLAG_SID BIT_U16(8)
124 #define IPV4_OPT_FLAG_SEC BIT_U16(9)
125 #define IPV4_OPT_FLAG_CIPSO BIT_U16(10)
126 #define IPV4_OPT_FLAG_RTRALT BIT_U16(11)
127 #define IPV4_OPT_FLAG_ESEC BIT_U16(12)
128 
129 /* helper structure with parsed ipv4 info */
130 typedef struct IPV4Vars_ {
131  uint16_t opt_cnt;
132  uint16_t opts_set;
133 } IPV4Vars;
134 
135 void DecodeIPV4RegisterTests(void);
136 
137 /** ----- Inline functions ----- */
138 
139 /**
140  * \brief Calculate or validate the checksum for the IP packet
141  *
142  * \param pkt Pointer to the start of the IP packet
143  * \param hlen Length of the IP header
144  * \param init The current checksum if validating, 0 if generating.
145  *
146  * \retval csum For validation 0 will be returned for success, for calculation
147  * this will be the checksum.
148  */
149 static inline uint16_t IPV4Checksum(const uint16_t *pkt, uint16_t hlen, uint16_t init)
150 {
151  uint32_t csum = init;
152 
153  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[6] + pkt[7] +
154  pkt[8] + pkt[9];
155 
156  hlen -= 20;
157  pkt += 10;
158 
159  if (hlen == 0) {
160  ;
161  } else if (hlen == 4) {
162  csum += pkt[0] + pkt[1];
163  } else if (hlen == 8) {
164  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3];
165  } else if (hlen == 12) {
166  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5];
167  } else if (hlen == 16) {
168  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
169  pkt[7];
170  } else if (hlen == 20) {
171  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
172  pkt[7] + pkt[8] + pkt[9];
173  } else if (hlen == 24) {
174  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
175  pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11];
176  } else if (hlen == 28) {
177  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
178  pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13];
179  } else if (hlen == 32) {
180  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
181  pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] +
182  pkt[14] + pkt[15];
183  } else if (hlen == 36) {
184  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
185  pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] +
186  pkt[14] + pkt[15] + pkt[16] + pkt[17];
187  } else if (hlen == 40) {
188  csum += pkt[0] + pkt[1] + pkt[2] + pkt[3] + pkt[4] + pkt[5] + pkt[6] +
189  pkt[7] + pkt[8] + pkt[9] + pkt[10] + pkt[11] + pkt[12] + pkt[13] +
190  pkt[14] + pkt[15] + pkt[16] + pkt[17] + pkt[18] + pkt[19];
191  }
192 
193  csum = (csum >> 16) + (csum & 0x0000FFFF);
194  csum += (csum >> 16);
195 
196  return (uint16_t) ~csum;
197 }
198 
199 #endif /* SURICATA_DECODE_IPV4_H */
IPV4Vars_
Definition: decode-ipv4.h:130
IPV4Hdr_::ip_addrs
uint16_t ip_addrs[4]
Definition: decode-ipv4.h:86
IPV4Hdr_::ip_ttl
uint8_t ip_ttl
Definition: decode-ipv4.h:78
IPV4Hdr_::ip_id
uint16_t ip_id
Definition: decode-ipv4.h:76
IPV4Hdr_::ip_tos
uint8_t ip_tos
Definition: decode-ipv4.h:74
DecodeIPV4RegisterTests
void DecodeIPV4RegisterTests(void)
Definition: decode-ipv4.c:1555
IPV4Opt_::len
uint8_t len
Definition: decode-ipv4.h:67
IPV4Hdr
struct IPV4Hdr_ IPV4Hdr
IPV4Hdr_::ip_src
struct in_addr ip_src
Definition: decode-ipv4.h:83
IPV4Vars
struct IPV4Vars_ IPV4Vars
IPV4Hdr_::ip_len
uint16_t ip_len
Definition: decode-ipv4.h:75
IPV4Vars_::opt_cnt
uint16_t opt_cnt
Definition: decode-ipv4.h:131
IPV4Opt_::data
const uint8_t * data
Definition: decode-ipv4.h:68
IPV4Hdr_
Definition: decode-ipv4.h:72
IPV4Hdr_::ip4_un1
struct IPV4Hdr_::@25::@26 ip4_un1
IPV4Opt_::type
uint8_t type
Definition: decode-ipv4.h:66
IPV4Opt
struct IPV4Opt_ IPV4Opt
IPV4Hdr_::ip_dst
struct in_addr ip_dst
Definition: decode-ipv4.h:84
IPV4Hdr_::ip4_hdrun1
union IPV4Hdr_::@25 ip4_hdrun1
IPV4Hdr_::ip_csum
uint16_t ip_csum
Definition: decode-ipv4.h:80
IPV4Vars_::opts_set
uint16_t opts_set
Definition: decode-ipv4.h:132
IPV4Hdr_::ip_off
uint16_t ip_off
Definition: decode-ipv4.h:77
IPV4Opt_
Definition: decode-ipv4.h:61
IPV4Hdr_::ip_proto
uint8_t ip_proto
Definition: decode-ipv4.h:79
IPV4Hdr_::ip_verhl
uint8_t ip_verhl
Definition: decode-ipv4.h:73