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-rw-r--r--src/lib/protocols/mail_smtp.c180
1 files changed, 180 insertions, 0 deletions
diff --git a/src/lib/protocols/mail_smtp.c b/src/lib/protocols/mail_smtp.c
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+++ b/src/lib/protocols/mail_smtp.c
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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_int_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_MAIL_SMTP, NDPI_REAL_PROTOCOL);
+}
+
+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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