util-lua-smtp.c

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/* Copyright (C) 2014-2025 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 casec Bachelors group
 *  \author Lauritz Prag Sømme <lauritz24@me.com>
 *  \author Levi Tobiassen <levi.tobiassen@gmail.com>
 *  \author Stian Hoel Bergseth <stian.bergseth@hig.no>
 *  \author Vinjar Hillestad <vinjar.hillestad@hig.no>
 */
 
#include "suricata-common.h"
#include "app-layer-smtp.h"
 
#include "util-lua.h"
#include "util-lua-common.h"
#include "util-lua-smtp.h"
 
#include "lua.h"
#include "lauxlib.h"
 
static const char smtp_tx_mt[] = "suricata:smtp:tx";
 
struct LuaSmtpTx {
    SCLuaTxRef ref; /* (flow, tx id); the tx is resolved on demand */
};
 
static int LuaSmtpGetTx(lua_State *L)
{
    if (!(LuaStateNeedProto(L, ALPROTO_SMTP))) {
        return LuaCallbackError(L, "error: protocol not SMTP");
    }
 
    /* prefer the transaction the engine is inspecting (the match setup
     * sets the registry entry in the tx-inspection phase); in the plain
     * packet phase the entry is empty and the flow's current
     * transaction is the one the script wants */
    uint64_t tx_id;
    SMTPTransaction *tx = (SMTPTransaction *)LuaStateGetTX(L);
    if (tx != NULL) {
        tx_id = LuaStateGetTxId(L);
    } else {
        Flow *flow = LuaStateGetFlow(L);
        if (flow == NULL) {
            return LuaCallbackError(L, "error: no flow found");
        }
        SMTPState *state = (SMTPState *)FlowGetAppState(flow);
        if (state == NULL) {
            return LuaCallbackError(L, "error: no SMTP state");
        }
        tx = state->curr_tx;
        if (tx == NULL) {
            return LuaCallbackError(L, "error: no SMTP transaction found");
        }
        tx_id = tx->tx_id;
    }
 
    struct LuaSmtpTx *lua_tx = SCLuaNewUserData(L, SCLUA_TUD_SMTP_TX, sizeof(*lua_tx));
    if (lua_tx == NULL) {
        return LuaCallbackError(L, "error: fail to allocate user data");
    }
    SCLuaTxRefInit(L, &lua_tx->ref, tx_id);
 
    luaL_getmetatable(L, smtp_tx_mt);
    lua_setmetatable(L, -2);
 
    return 1;
}
 
static int LuaSmtpTxGetMimeField(lua_State *L)
{
    struct LuaSmtpTx *ltx = SCLuaCheckUserData(L, 1, smtp_tx_mt, SCLUA_TUD_SMTP_TX);
    if (ltx == NULL) {
        lua_pushnil(L);
        return 1;
    }
    SCLUA_RESOLVE_TX(L, &ltx->ref, txptr);
    SMTPTransaction *tx = (SMTPTransaction *)txptr;
 
    if (tx->mime_state == NULL) {
        return LuaCallbackError(L, "no mime state");
    }
 
    const char *name = luaL_checkstring(L, 2);
    if (name == NULL) {
        return LuaCallbackError(L, "2nd argument missing, empty or wrong type");
    }
 
    const uint8_t *field_value;
    uint32_t field_len;
    if (SCMimeSmtpGetHeader(tx->mime_state, name, &field_value, &field_len)) {
        return LuaPushStringBuffer(L, field_value, field_len);
    }
 
    return LuaCallbackError(L, "request mime field not found");
}
 
static int LuaSmtpTxGetMimeList(lua_State *L)
{
    struct LuaSmtpTx *ltx = SCLuaCheckUserData(L, 1, smtp_tx_mt, SCLUA_TUD_SMTP_TX);
    if (ltx == NULL) {
        lua_pushnil(L);
        return 1;
    }
    SCLUA_RESOLVE_TX(L, &ltx->ref, txptr);
    SMTPTransaction *tx = (SMTPTransaction *)txptr;
 
    if (tx->mime_state == NULL) {
        return LuaCallbackError(L, "no mime state");
    }
 
    const uint8_t *field_name;
    uint32_t field_len;
    /* the FFI accessor is 0-based; the Lua table is 1-based */
    int num = 0;
    lua_newtable(L);
    while (SCMimeSmtpGetHeaderName(tx->mime_state, &field_name, &field_len, (uint32_t)num)) {
        lua_pushinteger(L, num + 1);
        LuaPushStringBuffer(L, field_name, field_len);
        lua_settable(L, -3);
        num++;
    }
    return 1;
}
 
static int LuaSmtpTxGetMailFrom(lua_State *L)
{
    struct LuaSmtpTx *ltx = SCLuaCheckUserData(L, 1, smtp_tx_mt, SCLUA_TUD_SMTP_TX);
    if (ltx == NULL) {
        lua_pushnil(L);
        return 1;
    }
    SCLUA_RESOLVE_TX(L, &ltx->ref, txptr);
    SMTPTransaction *tx = (SMTPTransaction *)txptr;
 
    if (tx->mail_from == NULL || tx->mail_from_len == 0) {
        lua_pushnil(L);
        return 1;
    }
 
    return LuaPushStringBuffer(L, tx->mail_from, tx->mail_from_len);
}
 
static int LuaSmtpTxGetRcptList(lua_State *L)
{
    struct LuaSmtpTx *ltx = SCLuaCheckUserData(L, 1, smtp_tx_mt, SCLUA_TUD_SMTP_TX);
    if (ltx == NULL) {
        lua_pushnil(L);
        return 1;
    }
    SCLUA_RESOLVE_TX(L, &ltx->ref, txptr);
    SMTPTransaction *tx = (SMTPTransaction *)txptr;
 
    /* Create a new table in luastate for rcpt list */
    lua_newtable(L);
    /* rcpt var for iterator */
    int u = 1;
    SMTPString *rcpt;
 
    TAILQ_FOREACH (rcpt, &tx->rcpt_to_list, next) {
        lua_pushinteger(L, u++);
        LuaPushStringBuffer(L, rcpt->str, rcpt->len);
        lua_settable(L, -3);
    }
 
    return 1;
}
 
static const struct luaL_Reg smtptxlib[] = {
    { "get_mime_field", LuaSmtpTxGetMimeField },
    { "get_mime_list", LuaSmtpTxGetMimeList },
    { "get_mail_from", LuaSmtpTxGetMailFrom },
    { "get_rcpt_list", LuaSmtpTxGetRcptList },
    { NULL, NULL },
};
 
static const struct luaL_Reg smtplib[] = {
    { "get_tx", LuaSmtpGetTx },
    { NULL, NULL },
};
 
int SCLuaLoadSmtpLib(lua_State *L)
{
    luaL_newmetatable(L, smtp_tx_mt);
    lua_pushvalue(L, -1);
    lua_setfield(L, -2, "__index");
    luaL_setfuncs(L, smtptxlib, 0);
 
    luaL_newlib(L, smtplib);
    return 1;
}