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/*
* mail_smtp.c
*
* Copyright (C) 2009-2011 by ipoque GmbH
* Copyright (C) 2011-15 - ntop.org
*
* This file is part of nDPI, an open source deep packet inspection
* library based on the OpenDPI and PACE technology by ipoque GmbH
*
* nDPI is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* nDPI 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with nDPI. If not, see <http://www.gnu.org/licenses/>.
*
*/
#include "ndpi_protocols.h"
#ifdef NDPI_PROTOCOL_MAIL_SMTP
#define SMTP_BIT_220 0x01
#define SMTP_BIT_250 0x02
#define SMTP_BIT_235 0x04
#define SMTP_BIT_334 0x08
#define SMTP_BIT_354 0x10
#define SMTP_BIT_HELO_EHLO 0x20
#define SMTP_BIT_MAIL 0x40
#define SMTP_BIT_RCPT 0x80
#define SMTP_BIT_AUTH 0x100
#define SMTP_BIT_STARTTLS 0x200
#define SMTP_BIT_DATA 0x400
#define SMTP_BIT_NOOP 0x800
#define SMTP_BIT_RSET 0x1000
#define SMTP_BIT_TlRM 0x2000
static void ndpi_int_mail_smtp_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_MAIL_SMTP, NDPI_PROTOCOL_UNKNOWN);
}
void ndpi_search_mail_smtp_tcp(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
// struct ndpi_id_struct *src=ndpi_struct->src;
// struct ndpi_id_struct *dst=ndpi_struct->dst;
NDPI_LOG(NDPI_PROTOCOL_MAIL_SMTP, ndpi_struct, NDPI_LOG_DEBUG, "search mail_smtp.\n");
if (packet->payload_packet_len > 2 && ntohs(get_u_int16_t(packet->payload, packet->payload_packet_len - 2)) == 0x0d0a) {
u_int8_t a;
u_int8_t bit_count = 0;
NDPI_PARSE_PACKET_LINE_INFO(ndpi_struct, flow,packet);
for (a = 0; a < packet->parsed_lines; a++) {
// expected server responses
if (packet->line[a].len >= 3) {
if (memcmp(packet->line[a].ptr, "220", 3) == 0) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_220;
} else if (memcmp(packet->line[a].ptr, "250", 3) == 0) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_250;
} else if (memcmp(packet->line[a].ptr, "235", 3) == 0) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_235;
} else if (memcmp(packet->line[a].ptr, "334", 3) == 0) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_334;
} else if (memcmp(packet->line[a].ptr, "354", 3) == 0) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_354;
}
}
// expected client requests
if (packet->line[a].len >= 5) {
if ((((packet->line[a].ptr[0] == 'H' || packet->line[a].ptr[0] == 'h')
&& (packet->line[a].ptr[1] == 'E' || packet->line[a].ptr[1] == 'e'))
|| ((packet->line[a].ptr[0] == 'E' || packet->line[a].ptr[0] == 'e')
&& (packet->line[a].ptr[1] == 'H' || packet->line[a].ptr[1] == 'h')))
&& (packet->line[a].ptr[2] == 'L' || packet->line[a].ptr[2] == 'l')
&& (packet->line[a].ptr[3] == 'O' || packet->line[a].ptr[3] == 'o')
&& packet->line[a].ptr[4] == ' ') {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_HELO_EHLO;
} else if ((packet->line[a].ptr[0] == 'M' || packet->line[a].ptr[0] == 'm')
&& (packet->line[a].ptr[1] == 'A' || packet->line[a].ptr[1] == 'a')
&& (packet->line[a].ptr[2] == 'I' || packet->line[a].ptr[2] == 'i')
&& (packet->line[a].ptr[3] == 'L' || packet->line[a].ptr[3] == 'l')
&& packet->line[a].ptr[4] == ' ') {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_MAIL;
} else if ((packet->line[a].ptr[0] == 'R' || packet->line[a].ptr[0] == 'r')
&& (packet->line[a].ptr[1] == 'C' || packet->line[a].ptr[1] == 'c')
&& (packet->line[a].ptr[2] == 'P' || packet->line[a].ptr[2] == 'p')
&& (packet->line[a].ptr[3] == 'T' || packet->line[a].ptr[3] == 't')
&& packet->line[a].ptr[4] == ' ') {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_RCPT;
} else if ((packet->line[a].ptr[0] == 'A' || packet->line[a].ptr[0] == 'a')
&& (packet->line[a].ptr[1] == 'U' || packet->line[a].ptr[1] == 'u')
&& (packet->line[a].ptr[2] == 'T' || packet->line[a].ptr[2] == 't')
&& (packet->line[a].ptr[3] == 'H' || packet->line[a].ptr[3] == 'h')
&& packet->line[a].ptr[4] == ' ') {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_AUTH;
}
}
if (packet->line[a].len >= 8) {
if ((packet->line[a].ptr[0] == 'S' || packet->line[a].ptr[0] == 's')
&& (packet->line[a].ptr[1] == 'T' || packet->line[a].ptr[1] == 't')
&& (packet->line[a].ptr[2] == 'A' || packet->line[a].ptr[2] == 'a')
&& (packet->line[a].ptr[3] == 'R' || packet->line[a].ptr[3] == 'r')
&& (packet->line[a].ptr[4] == 'T' || packet->line[a].ptr[0] == 't')
&& (packet->line[a].ptr[5] == 'T' || packet->line[a].ptr[1] == 't')
&& (packet->line[a].ptr[6] == 'L' || packet->line[a].ptr[2] == 'l')
&& (packet->line[a].ptr[7] == 'S' || packet->line[a].ptr[3] == 's')) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_STARTTLS;
}
}
if (packet->line[a].len >= 4) {
if ((packet->line[a].ptr[0] == 'D' || packet->line[a].ptr[0] == 'd')
&& (packet->line[a].ptr[1] == 'A' || packet->line[a].ptr[1] == 'a')
&& (packet->line[a].ptr[2] == 'T' || packet->line[a].ptr[2] == 't')
&& (packet->line[a].ptr[3] == 'A' || packet->line[a].ptr[3] == 'a')) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_DATA;
} else if ((packet->line[a].ptr[0] == 'N' || packet->line[a].ptr[0] == 'n')
&& (packet->line[a].ptr[1] == 'O' || packet->line[a].ptr[1] == 'o')
&& (packet->line[a].ptr[2] == 'O' || packet->line[a].ptr[2] == 'o')
&& (packet->line[a].ptr[3] == 'P' || packet->line[a].ptr[3] == 'p')) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_NOOP;
} else if ((packet->line[a].ptr[0] == 'R' || packet->line[a].ptr[0] == 'r')
&& (packet->line[a].ptr[1] == 'S' || packet->line[a].ptr[1] == 's')
&& (packet->line[a].ptr[2] == 'E' || packet->line[a].ptr[2] == 'e')
&& (packet->line[a].ptr[3] == 'T' || packet->line[a].ptr[3] == 't')) {
flow->l4.tcp.smtp_command_bitmask |= SMTP_BIT_RSET;
}
}
}
// now count the bits set in the bitmask
if (flow->l4.tcp.smtp_command_bitmask != 0) {
for (a = 0; a < 16; a++) {
bit_count += (flow->l4.tcp.smtp_command_bitmask >> a) & 0x01;
}
}
NDPI_LOG(NDPI_PROTOCOL_MAIL_SMTP, ndpi_struct, NDPI_LOG_DEBUG, "seen smtp commands and responses: %u.\n",
bit_count);
if (bit_count >= 3) {
NDPI_LOG(NDPI_PROTOCOL_MAIL_SMTP, ndpi_struct, NDPI_LOG_DEBUG, "mail smtp identified\n");
ndpi_int_mail_smtp_add_connection(ndpi_struct, flow);
return;
}
if (bit_count >= 1 && flow->packet_counter < 12) {
return;
}
}
/* when the first or second packets are split into two packets, those packets are ignored. */
if (flow->packet_counter <= 4 &&
packet->payload_packet_len >= 4 &&
(ntohs(get_u_int16_t(packet->payload, packet->payload_packet_len - 2)) == 0x0d0a
|| memcmp(packet->payload, "220", 3) == 0 || memcmp(packet->payload, "EHLO", 4) == 0)) {
NDPI_LOG(NDPI_PROTOCOL_MAIL_SMTP, ndpi_struct, NDPI_LOG_DEBUG, "maybe SMTP, need next packet.\n");
return;
}
NDPI_LOG(NDPI_PROTOCOL_MAIL_SMTP, ndpi_struct, NDPI_LOG_DEBUG, "exclude smtp\n");
NDPI_ADD_PROTOCOL_TO_BITMASK(flow->excluded_protocol_bitmask, NDPI_PROTOCOL_MAIL_SMTP);
}
#endif
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