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/*
* mail_pop.c
*
* Copyright (C) 2011-22 - ntop.org
* Copyright (C) 2009-11 - ipoque GmbH
*
* 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_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_MAIL_POP
#include "ndpi_api.h"
#include "ndpi_private.h"
#define POP_BIT_AUTH 0x0001
#define POP_BIT_APOP 0x0002
#define POP_BIT_USER 0x0004
#define POP_BIT_PASS 0x0008
#define POP_BIT_CAPA 0x0010
#define POP_BIT_LIST 0x0020
#define POP_BIT_STAT 0x0040
#define POP_BIT_UIDL 0x0080
#define POP_BIT_RETR 0x0100
#define POP_BIT_DELE 0x0200
#define POP_BIT_STLS 0x0400
static void ndpi_int_mail_pop_add_connection(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow,
u_int16_t protocol) {
NDPI_LOG_INFO(ndpi_struct, "mail_pop identified\n");
flow->guessed_protocol_id = NDPI_PROTOCOL_UNKNOWN; /* Avoid POP3S to be used s sub-protocol */
ndpi_set_detected_protocol(ndpi_struct, flow, protocol, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
/* **************************************** */
static void popInitExtraPacketProcessing(struct ndpi_flow_struct *flow);
/* **************************************** */
static int ndpi_int_mail_pop_check_for_client_commands(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
if(packet->payload_packet_len > 4) {
if((packet->payload[0] == 'A' || packet->payload[0] == 'a')
&& (packet->payload[1] == 'U' || packet->payload[1] == 'u')
&& (packet->payload[2] == 'T' || packet->payload[2] == 't')
&& (packet->payload[3] == 'H' || packet->payload[3] == 'h')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_AUTH;
return 1;
} else if((packet->payload[0] == 'A' || packet->payload[0] == 'a')
&& (packet->payload[1] == 'P' || packet->payload[1] == 'p')
&& (packet->payload[2] == 'O' || packet->payload[2] == 'o')
&& (packet->payload[3] == 'P' || packet->payload[3] == 'p')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_APOP;
return 1;
} else if((packet->payload[0] == 'U' || packet->payload[0] == 'u')
&& (packet->payload[1] == 'S' || packet->payload[1] == 's')
&& (packet->payload[2] == 'E' || packet->payload[2] == 'e')
&& (packet->payload[3] == 'R' || packet->payload[3] == 'r')) {
char buf[64];
ndpi_user_pwd_payload_copy((u_int8_t*)flow->l4.tcp.ftp_imap_pop_smtp.username,
sizeof(flow->l4.tcp.ftp_imap_pop_smtp.username), 5,
packet->payload, packet->payload_packet_len);
snprintf(buf, sizeof(buf), "Found username (%s)",
flow->l4.tcp.ftp_imap_pop_smtp.username);
ndpi_set_risk(flow, NDPI_CLEAR_TEXT_CREDENTIALS, buf);
flow->l4.tcp.pop_command_bitmask |= POP_BIT_USER;
return 1;
} else if((packet->payload[0] == 'P' || packet->payload[0] == 'p')
&& (packet->payload[1] == 'A' || packet->payload[1] == 'a')
&& (packet->payload[2] == 'S' || packet->payload[2] == 's')
&& (packet->payload[3] == 'S' || packet->payload[3] == 's')) {
ndpi_user_pwd_payload_copy((u_int8_t*)flow->l4.tcp.ftp_imap_pop_smtp.password,
sizeof(flow->l4.tcp.ftp_imap_pop_smtp.password), 5,
packet->payload, packet->payload_packet_len);
ndpi_set_risk(flow, NDPI_CLEAR_TEXT_CREDENTIALS, "Found password");
flow->l4.tcp.pop_command_bitmask |= POP_BIT_PASS;
return 1;
} else if((packet->payload[0] == 'C' || packet->payload[0] == 'c')
&& (packet->payload[1] == 'A' || packet->payload[1] == 'a')
&& (packet->payload[2] == 'P' || packet->payload[2] == 'p')
&& (packet->payload[3] == 'A' || packet->payload[3] == 'a')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_CAPA;
return 1;
} else if((packet->payload[0] == 'L' || packet->payload[0] == 'l')
&& (packet->payload[1] == 'I' || packet->payload[1] == 'i')
&& (packet->payload[2] == 'S' || packet->payload[2] == 's')
&& (packet->payload[3] == 'T' || packet->payload[3] == 't')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_LIST;
return 1;
} else if((packet->payload[0] == 'S' || packet->payload[0] == 's')
&& (packet->payload[1] == 'T' || packet->payload[1] == 't')
&& (packet->payload[2] == 'A' || packet->payload[2] == 'a')
&& (packet->payload[3] == 'T' || packet->payload[3] == 't')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_STAT;
return 1;
} else if((packet->payload[0] == 'U' || packet->payload[0] == 'u')
&& (packet->payload[1] == 'I' || packet->payload[1] == 'i')
&& (packet->payload[2] == 'D' || packet->payload[2] == 'd')
&& (packet->payload[3] == 'L' || packet->payload[3] == 'l')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_UIDL;
return 1;
} else if((packet->payload[0] == 'R' || packet->payload[0] == 'r')
&& (packet->payload[1] == 'E' || packet->payload[1] == 'e')
&& (packet->payload[2] == 'T' || packet->payload[2] == 't')
&& (packet->payload[3] == 'R' || packet->payload[3] == 'r')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_RETR;
return 1;
} else if((packet->payload[0] == 'D' || packet->payload[0] == 'd')
&& (packet->payload[1] == 'E' || packet->payload[1] == 'e')
&& (packet->payload[2] == 'L' || packet->payload[2] == 'l')
&& (packet->payload[3] == 'E' || packet->payload[3] == 'e')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_DELE;
return 1;
} else if((packet->payload[0] == 'S' || packet->payload[0] == 's')
&& (packet->payload[1] == 'T' || packet->payload[1] == 't')
&& (packet->payload[2] == 'L' || packet->payload[2] == 'l')
&& (packet->payload[3] == 'S' || packet->payload[3] == 's')) {
flow->l4.tcp.pop_command_bitmask |= POP_BIT_STLS;
flow->l4.tcp.mail_imap_starttls = 1;
return 1;
}
}
return 0;
}
static void ndpi_search_mail_pop_tcp(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
u_int8_t a = 0;
u_int8_t bit_count = 0;
NDPI_LOG_DBG(ndpi_struct, "search mail_pop\n");
if((packet->payload_packet_len > 3
&& (packet->payload[0] == '+' && (packet->payload[1] == 'O' || packet->payload[1] == 'o')
&& (packet->payload[2] == 'K' || packet->payload[2] == 'k')))
|| (packet->payload_packet_len > 4
&& (packet->payload[0] == '-' && (packet->payload[1] == 'E' || packet->payload[1] == 'e')
&& (packet->payload[2] == 'R' || packet->payload[2] == 'r')
&& (packet->payload[3] == 'R' || packet->payload[3] == 'r')))) {
// +OK or -ERR seen
flow->l4.tcp.mail_pop_stage += 1;
if(packet->payload[0] == '+' && flow->l4.tcp.mail_imap_starttls == 1) {
NDPI_LOG_DBG2(ndpi_struct, "starttls detected\n");
ndpi_int_mail_pop_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_MAIL_POPS);
if(ndpi_struct->cfg.pop_opportunistic_tls_enabled) {
NDPI_LOG_DBG(ndpi_struct, "Switching to [%d/%d]\n",
flow->detected_protocol_stack[0], flow->detected_protocol_stack[1]);
/* We are done (in POP dissector): delegating TLS... */
switch_extra_dissection_to_tls(ndpi_struct, flow);
return;
}
}
if(packet->payload[0] == '-' && flow->l4.tcp.mail_imap_starttls == 1)
flow->l4.tcp.mail_imap_starttls = 0;
} else if(!ndpi_int_mail_pop_check_for_client_commands(ndpi_struct, flow)) {
goto maybe_split_pop;
}
if(packet->payload_packet_len > 2 && ntohs(get_u_int16_t(packet->payload, packet->payload_packet_len - 2)) == 0x0d0a) {
// count the bits set in the bitmask
if(flow->l4.tcp.pop_command_bitmask != 0) {
for (a = 0; a < 16; a++) {
bit_count += (flow->l4.tcp.pop_command_bitmask >> a) & 0x01;
}
}
NDPI_LOG_DBG2(ndpi_struct,
"mail_pop +OK/-ERR responses: %u, unique commands: %u\n",
flow->l4.tcp.mail_pop_stage, bit_count);
if((bit_count + flow->l4.tcp.mail_pop_stage) >= 3) {
if(flow->l4.tcp.mail_pop_stage > 0) {
if((flow->l4.tcp.ftp_imap_pop_smtp.password[0] != '\0')
|| (flow->l4.tcp.mail_pop_stage >= 3)) {
ndpi_int_mail_pop_add_connection(ndpi_struct, flow, NDPI_PROTOCOL_MAIL_POP);
if(flow->l4.tcp.ftp_imap_pop_smtp.password[0] == '\0')
popInitExtraPacketProcessing(flow);
}
}
return;
} else
return;
} else {
// first part of a split packet
NDPI_LOG_DBG2(ndpi_struct,
"mail_pop command without line ending -> skip\n");
return;
}
maybe_split_pop:
if(((packet->payload_packet_len > 2 && ntohs(get_u_int16_t(packet->payload, packet->payload_packet_len - 2)) == 0x0d0a)
|| flow->l4.tcp.pop_command_bitmask != 0 || flow->l4.tcp.mail_pop_stage != 0) && flow->packet_counter < 12) {
// maybe part of a split pop packet
NDPI_LOG_DBG2(ndpi_struct,
"maybe part of split mail_pop packet -> skip\n");
return;
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
/* **************************************** */
int ndpi_extra_search_mail_pop_tcp(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
int rc;
ndpi_search_mail_pop_tcp(ndpi_struct, flow);
rc = (flow->l4.tcp.ftp_imap_pop_smtp.password[0] == '\0') ? 1 : 0;
#ifdef POP_DEBUG
printf("**** %s() [rc: %d]\n", __FUNCTION__, rc);
#endif
return(rc);
}
/* **************************************** */
static void popInitExtraPacketProcessing(struct ndpi_flow_struct *flow) {
#ifdef POP_DEBUG
printf("**** %s()\n", __FUNCTION__);
#endif
/* At most 7 packets should almost always be enough */
flow->max_extra_packets_to_check = 7;
flow->extra_packets_func = ndpi_extra_search_mail_pop_tcp;
}
/* **************************************** */
void init_mail_pop_dissector(struct ndpi_detection_module_struct *ndpi_struct,
u_int32_t *id) {
ndpi_set_bitmask_protocol_detection("MAIL_POP", ndpi_struct, *id,
NDPI_PROTOCOL_MAIL_POP,
ndpi_search_mail_pop_tcp,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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