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/*
* sip.c
*
* Copyright (C) 2009-11 - ipoque GmbH
* Copyright (C) 2011-22 - 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_protocol_ids.h"
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_SIP
#include "ndpi_api.h"
#include "ndpi_private.h"
static void ndpi_int_sip_add_connection(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_SIP, NDPI_PROTOCOL_UNKNOWN, NDPI_CONFIDENCE_DPI);
}
/* ********************************************************** */
static int search_cmd(struct ndpi_detection_module_struct *ndpi_struct)
{
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
const u_int8_t *packet_payload = packet->payload;
u_int32_t payload_len = packet->payload_packet_len;
const char **cs;
size_t length;
const char *cmds_a[] = { "Ack sip",
"Ack tel",
NULL };
const char *cmds_b[] = { "Bye sip",
NULL};
const char *cmds_c[] = { "Cancel sip",
"Cancel tel",
NULL};
const char *cmds_i[] = { "Invite sip",
"Info sip",
NULL};
const char *cmds_m[] = { "Message sip",
NULL};
const char *cmds_n[] = { "Notify sip",
NULL};
const char *cmds_o[] = { "Options sip",
"Options tel",
NULL};
const char *cmds_p[] = { "Publish sip",
"Prack sip",
NULL};
const char *cmds_r[] = { "Register sip",
"Refer sip",
NULL};
const char *cmds_s[] = { "Subscribe sip",
"SIP/2.0", /* Reply; useful with asymmetric flows */
NULL};
switch(packet_payload[0]) {
case 'a':
case 'A':
cs = cmds_a;
break;
case 'b':
case 'B':
cs = cmds_b;
break;
case 'c':
case 'C':
cs = cmds_c;
break;
case 'i':
case 'I':
cs = cmds_i;
break;
case 'm':
case 'M':
cs = cmds_m;
break;
case 'n':
case 'N':
cs = cmds_n;
break;
case 'o':
case 'O':
cs = cmds_o;
break;
case 'p':
case 'P':
cs = cmds_p;
break;
case 'r':
case 'R':
cs = cmds_r;
break;
case 's':
case 'S':
cs = cmds_s;
break;
default:
return 0;
}
while(*cs) {
length = strlen(*cs);
if(payload_len > length &&
strncasecmp((const char *)packet_payload, *cs, length) == 0) {
NDPI_LOG_DBG(ndpi_struct, "Matching with [%s]\n", *cs);
return 1;
}
cs++;
}
return 0;
}
void ndpi_search_sip(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &ndpi_struct->packet;
const u_int8_t *packet_payload = packet->payload;
u_int32_t payload_len = packet->payload_packet_len;
NDPI_LOG_DBG(ndpi_struct, "Searching for SIP\n");
if(flow->packet_counter >= 8) {
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if(payload_len > 4) {
/* search for STUN Turn ChannelData Prefix */
u_int16_t message_len = ntohs(get_u_int16_t(packet->payload, 2));
if(payload_len - 4 == message_len) {
NDPI_LOG_DBG2(ndpi_struct, "found STUN TURN ChannelData prefix\n");
payload_len -= 4;
packet_payload += 4;
}
if(!isprint(packet_payload[0])) {
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
}
if(payload_len == 5 && memcmp(packet_payload, "hello", 5) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found sip via HELLO (kind of ping)\n");
ndpi_int_sip_add_connection(ndpi_struct, flow);
return;
}
if(payload_len >= 30) { /* Arbitrary value: SIP packets are quite big */
if(search_cmd(ndpi_struct) == 1) {
NDPI_LOG_INFO(ndpi_struct, "found sip command\n");
ndpi_int_sip_add_connection(ndpi_struct, flow);
return;
}
}
}
/* ********************************************************** */
void init_sip_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id) {
ndpi_set_bitmask_protocol_detection("SIP", ndpi_struct, *id,
NDPI_PROTOCOL_SIP,
ndpi_search_sip,
NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_TCP_OR_UDP_WITH_PAYLOAD_WITHOUT_RETRANSMISSION,/* Fix courtesy of Miguel Quesada <mquesadab@gmail.com> */
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}
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