nDPI/src/lib/protocols/bittorrent.c
Luca Deri ab9246f51f Adedd DTLS check in STUN
Uodated (C)
2019-09-21 09:16:56 +02:00

503 lines
18 KiB
C

/*
* bittorrent.c
*
* Copyright (C) 2009-2011 by ipoque GmbH
* Copyright (C) 2011-19 - 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_BITTORRENT
#include "ndpi_api.h"
#define NDPI_PROTOCOL_UNSAFE_DETECTION 0
#define NDPI_PROTOCOL_SAFE_DETECTION 1
#define NDPI_PROTOCOL_PLAIN_DETECTION 0
#define NDPI_PROTOCOL_WEBSEED_DETECTION 2
struct ndpi_utp_hdr {
u_int8_t h_version:4, h_type:4, next_extension;
u_int16_t connection_id;
u_int32_t ts_usec, tdiff_usec, window_size;
u_int16_t sequence_nr, ack_nr;
};
static u_int8_t is_utp_pkt(const u_int8_t *payload, u_int payload_len) {
struct ndpi_utp_hdr *h = (struct ndpi_utp_hdr*)payload;
if(payload_len < sizeof(struct ndpi_utp_hdr)) return(0);
if(h->h_version != 1) return(0);
if(h->h_type > 4) return(0);
if(h->next_extension > 2) return(0);
if(ntohl(h->window_size) > 65565) return(0);
return(1);
}
static void ndpi_add_connection_as_bittorrent(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow,
int bt_offset, int check_hash,
const u_int8_t save_detection, const u_int8_t encrypted_connection)
{
if(check_hash) {
const char *bt_hash = NULL; /* 20 bytes long */
if(bt_offset == -1) {
const char *bt_magic = ndpi_strnstr((const char *)flow->packet.payload,
"BitTorrent protocol", flow->packet.payload_packet_len);
if(bt_magic)
bt_hash = &bt_magic[19];
} else
bt_hash = (const char*)&flow->packet.payload[28];
if(!ndpi_struct->disable_metadata_export) {
if(bt_hash) memcpy(flow->protos.bittorrent.hash, bt_hash, 20);
}
}
ndpi_int_change_protocol(ndpi_struct, flow, NDPI_PROTOCOL_BITTORRENT, NDPI_PROTOCOL_UNKNOWN);
}
static u_int8_t ndpi_int_search_bittorrent_tcp_zero(struct ndpi_detection_module_struct
*ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
u_int16_t a = 0;
if(packet->payload_packet_len == 1 && packet->payload[0] == 0x13) {
/* reset stage back to 0 so we will see the next packet here too */
flow->bittorrent_stage = 0;
return 0;
}
if(flow->packet_counter == 2 && packet->payload_packet_len > 20) {
if(memcmp(&packet->payload[0], "BitTorrent protocol", 19) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: plain\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, 19, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
}
if(packet->payload_packet_len > 20) {
/* test for match 0x13+"BitTorrent protocol" */
if(packet->payload[0] == 0x13) {
if(memcmp(&packet->payload[1], "BitTorrent protocol", 19) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: plain\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, 20, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
}
}
if(packet->payload_packet_len > 23 && memcmp(packet->payload, "GET /webseed?info_hash=", 23) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: plain webseed\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_WEBSEED_DETECTION);
return 1;
}
/* seen Azureus as server for webseed, possibly other servers existing, to implement */
/* is Server: hypertracker Bittorrent? */
/* no asymmetric detection possible for answer of pattern "GET /data?fid=". */
if(packet->payload_packet_len > 60
&& memcmp(packet->payload, "GET /data?fid=", 14) == 0 && memcmp(&packet->payload[54], "&size=", 6) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: plain Bitcomet persistent seed\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_WEBSEED_DETECTION);
return 1;
}
if(packet->payload_packet_len > 90 && (memcmp(packet->payload, "GET ", 4) == 0
|| memcmp(packet->payload, "POST ", 5) == 0)) {
const u_int8_t *ptr = &packet->payload[4];
u_int16_t len = packet->payload_packet_len - 4;
/* parse complete get packet here into line structure elements */
ndpi_parse_packet_line_info(ndpi_struct, flow);
/* answer to this pattern is HTTP....Server: hypertracker */
if(packet->user_agent_line.ptr != NULL
&& ((packet->user_agent_line.len > 8 && memcmp(packet->user_agent_line.ptr, "Azureus ", 8) == 0)
|| (packet->user_agent_line.len >= 10 && memcmp(packet->user_agent_line.ptr, "BitTorrent", 10) == 0)
|| (packet->user_agent_line.len >= 11 && memcmp(packet->user_agent_line.ptr, "BTWebClient", 11) == 0))) {
NDPI_LOG_INFO(ndpi_struct, "found BT: Azureus /Bittorrent user agent\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_WEBSEED_DETECTION);
return 1;
}
if(packet->user_agent_line.ptr != NULL
&& (packet->user_agent_line.len >= 9 && memcmp(packet->user_agent_line.ptr, "Shareaza ", 9) == 0)
&& (packet->parsed_lines > 8 && packet->line[8].ptr != 0
&& packet->line[8].len >= 9 && memcmp(packet->line[8].ptr, "X-Queue: ", 9) == 0)) {
NDPI_LOG_INFO(ndpi_struct, "found BT: Shareaza detected\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_WEBSEED_DETECTION);
return 1;
}
/* this is a self built client, not possible to catch asymmetrically */
if((packet->parsed_lines == 10 || (packet->parsed_lines == 11 && packet->line[11].len == 0))
&& packet->user_agent_line.ptr != NULL
&& packet->user_agent_line.len > 12
&& memcmp(packet->user_agent_line.ptr, "Mozilla/4.0 ",
12) == 0
&& packet->host_line.ptr != NULL
&& packet->host_line.len >= 7
&& packet->line[2].ptr != NULL
&& packet->line[2].len > 14
&& memcmp(packet->line[2].ptr, "Keep-Alive: 300", 15) == 0
&& packet->line[3].ptr != NULL
&& packet->line[3].len > 21
&& memcmp(packet->line[3].ptr, "Connection: Keep-alive", 22) == 0
&& packet->line[4].ptr != NULL
&& packet->line[4].len > 10
&& (memcmp(packet->line[4].ptr, "Accpet: */*", 11) == 0
|| memcmp(packet->line[4].ptr, "Accept: */*", 11) == 0)
&& packet->line[5].ptr != NULL
&& packet->line[5].len > 12
&& memcmp(packet->line[5].ptr, "Range: bytes=", 13) == 0
&& packet->line[7].ptr != NULL
&& packet->line[7].len > 15
&& memcmp(packet->line[7].ptr, "Pragma: no-cache", 16) == 0
&& packet->line[8].ptr != NULL
&& packet->line[8].len > 22 && memcmp(packet->line[8].ptr, "Cache-Control: no-cache", 23) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: Bitcomet LTS\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_UNSAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
/* FlashGet pattern */
if(packet->parsed_lines == 8
&& packet->user_agent_line.ptr != NULL
&& packet->user_agent_line.len > (sizeof("Mozilla/4.0 (compatible; MSIE 6.0;") - 1)
&& memcmp(packet->user_agent_line.ptr, "Mozilla/4.0 (compatible; MSIE 6.0;",
sizeof("Mozilla/4.0 (compatible; MSIE 6.0;") - 1) == 0
&& packet->host_line.ptr != NULL
&& packet->host_line.len >= 7
&& packet->line[2].ptr != NULL
&& packet->line[2].len == 11
&& memcmp(packet->line[2].ptr, "Accept: */*", 11) == 0
&& packet->line[3].ptr != NULL && packet->line[3].len >= (sizeof("Referer: ") - 1)
&& memcmp(packet->line[3].ptr, "Referer: ", sizeof("Referer: ") - 1) == 0
&& packet->line[5].ptr != NULL
&& packet->line[5].len > 13
&& memcmp(packet->line[5].ptr, "Range: bytes=", 13) == 0
&& packet->line[6].ptr != NULL
&& packet->line[6].len > 21 && memcmp(packet->line[6].ptr, "Connection: Keep-Alive", 22) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: FlashGet\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_UNSAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
if(packet->parsed_lines == 7
&& packet->user_agent_line.ptr != NULL
&& packet->user_agent_line.len > (sizeof("Mozilla/4.0 (compatible; MSIE 6.0;") - 1)
&& memcmp(packet->user_agent_line.ptr, "Mozilla/4.0 (compatible; MSIE 6.0;",
sizeof("Mozilla/4.0 (compatible; MSIE 6.0;") - 1) == 0
&& packet->host_line.ptr != NULL
&& packet->host_line.len >= 7
&& packet->line[2].ptr != NULL
&& packet->line[2].len == 11
&& memcmp(packet->line[2].ptr, "Accept: */*", 11) == 0
&& packet->line[3].ptr != NULL && packet->line[3].len >= (sizeof("Referer: ") - 1)
&& memcmp(packet->line[3].ptr, "Referer: ", sizeof("Referer: ") - 1) == 0
&& packet->line[5].ptr != NULL
&& packet->line[5].len > 21 && memcmp(packet->line[5].ptr, "Connection: Keep-Alive", 22) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: FlashGet\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_UNSAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
/* answer to this pattern is not possible to implement asymmetrically */
while (1) {
if(len < 50 || ptr[0] == 0x0d) {
goto ndpi_end_bt_tracker_check;
}
if(memcmp(ptr, "info_hash=", 10) == 0) {
break;
}
len--;
ptr++;
}
NDPI_LOG_DBG2(ndpi_struct, " BT stat: tracker info hash found\n");
/* len is > 50, so save operation here */
len -= 10;
ptr += 10;
/* parse bt hash */
for (a = 0; a < 20; a++) {
if(len < 3) {
goto ndpi_end_bt_tracker_check;
}
if(*ptr == '%') {
u_int8_t x1 = 0xFF;
u_int8_t x2 = 0xFF;
if(ptr[1] >= '0' && ptr[1] <= '9') {
x1 = ptr[1] - '0';
}
if(ptr[1] >= 'a' && ptr[1] <= 'f') {
x1 = 10 + ptr[1] - 'a';
}
if(ptr[1] >= 'A' && ptr[1] <= 'F') {
x1 = 10 + ptr[1] - 'A';
}
if(ptr[2] >= '0' && ptr[2] <= '9') {
x2 = ptr[2] - '0';
}
if(ptr[2] >= 'a' && ptr[2] <= 'f') {
x2 = 10 + ptr[2] - 'a';
}
if(ptr[2] >= 'A' && ptr[2] <= 'F') {
x2 = 10 + ptr[2] - 'A';
}
if(x1 == 0xFF || x2 == 0xFF) {
goto ndpi_end_bt_tracker_check;
}
ptr += 3;
len -= 3;
} else if(*ptr >= 32 && *ptr < 127) {
ptr++;
len--;
} else {
goto ndpi_end_bt_tracker_check;
}
}
NDPI_LOG_INFO(ndpi_struct, "found BT: tracker info hash parsed\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
ndpi_end_bt_tracker_check:
if(packet->payload_packet_len == 80) {
/* Warez 80 Bytes Packet
* +----------------+---------------+-----------------+-----------------+
* |20 BytesPattern | 32 Bytes Value| 12 BytesPattern | 16 Bytes Data |
* +----------------+---------------+-----------------+-----------------+
* 20 BytesPattern : 4c 00 00 00 ff ff ff ff 57 00 00 00 00 00 00 00 20 00 00 00
* 12 BytesPattern : 28 23 00 00 01 00 00 00 10 00 00 00
* */
static const char pattern_20_bytes[20] = { 0x4c, 0x00, 0x00, 0x00, 0xff,
0xff, 0xff, 0xff, 0x57, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00
};
static const char pattern_12_bytes[12] = { 0x28, 0x23, 0x00, 0x00, 0x01,
0x00, 0x00, 0x00, 0x10, 0x00,
0x00, 0x00
};
/* did not see this pattern anywhere */
if((memcmp(&packet->payload[0], pattern_20_bytes, 20) == 0)
&& (memcmp(&packet->payload[52], pattern_12_bytes, 12) == 0)) {
NDPI_LOG_INFO(ndpi_struct, "found BT: Warez - Plain\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return 1;
}
}
else if(packet->payload_packet_len > 50) {
if(memcmp(packet->payload, "GET", 3) == 0) {
ndpi_parse_packet_line_info(ndpi_struct, flow);
/* haven't fount this pattern anywhere */
if(packet->host_line.ptr != NULL
&& packet->host_line.len >= 9 && memcmp(packet->host_line.ptr, "ip2p.com:", 9) == 0) {
NDPI_LOG_INFO(ndpi_struct, "found BT: Warez - Plain Host: ip2p.com: pattern\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_WEBSEED_DETECTION);
return 1;
}
}
}
return 0;
}
/*Search for BitTorrent commands*/
static void ndpi_int_search_bittorrent_tcp(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
if(packet->payload_packet_len == 0) {
return;
}
if(flow->bittorrent_stage == 0 && packet->payload_packet_len != 0) {
/* exclude stage 0 detection from next run */
flow->bittorrent_stage = 1;
if(ndpi_int_search_bittorrent_tcp_zero(ndpi_struct, flow) != 0) {
NDPI_LOG_DBG2(ndpi_struct, "stage 0 has detected something, returning\n");
return;
}
NDPI_LOG_DBG2(ndpi_struct, "stage 0 has no direct detection, fall through\n");
}
return;
}
void ndpi_search_bittorrent(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow)
{
struct ndpi_packet_struct *packet = &flow->packet;
char *bt_proto = NULL;
/* This is broadcast */
if(packet->iph
&& (((packet->iph->saddr == 0xFFFFFFFF) || (packet->iph->daddr == 0xFFFFFFFF))
|| (packet->udp
&& ((ntohs(packet->udp->source) == 3544) /* teredo.c */
|| (ntohs(packet->udp->dest) == 3544))))) {
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
return;
}
if(packet->detected_protocol_stack[0] != NDPI_PROTOCOL_BITTORRENT) {
/* check for tcp retransmission here */
if((packet->tcp != NULL)
&& (packet->tcp_retransmission == 0 || packet->num_retried_bytes)) {
ndpi_int_search_bittorrent_tcp(ndpi_struct, flow);
}
else if(packet->udp != NULL) {
char *bt_search = "BT-SEARCH * HTTP/1.1\r\n";
if((ntohs(packet->udp->source) < 1024)
|| (ntohs(packet->udp->dest) < 1024) /* High ports only */)
return;
/*
Check for uTP http://www.bittorrent.org/beps/bep_0029.html
wireshark/epan/dissectors/packet-bt-utp.c
*/
if(packet->payload_packet_len >= 23 /* min header size */) {
if(strncmp((const char*)packet->payload, bt_search, strlen(bt_search)) == 0) {
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 1,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return;
} else {
/* Check if this is protocol v0 */
u_int8_t v0_extension = packet->payload[17];
u_int8_t v0_flags = packet->payload[18];
/* Check if this is protocol v1 */
u_int8_t v1_version = packet->payload[0];
u_int8_t v1_extension = packet->payload[1];
u_int32_t v1_window_size = *((u_int32_t*)&packet->payload[12]);
if(is_utp_pkt(packet->payload, packet->payload_packet_len))
goto bittorrent_found;
else if((packet->payload[0]== 0x60)
&& (packet->payload[1]== 0x0)
&& (packet->payload[2]== 0x0)
&& (packet->payload[3]== 0x0)
&& (packet->payload[4]== 0x0)) {
/* Heuristic */
bt_proto = ndpi_strnstr((const char *)&packet->payload[20], "BitTorrent protocol", packet->payload_packet_len-20);
goto bittorrent_found;
/* CSGO/DOTA conflict */
} else if(flow->packet_counter > 8 && ((v1_version & 0x0f) == 1)
&& ((v1_version >> 4) < 5 /* ST_NUM_STATES */)
&& (v1_extension < 3 /* EXT_NUM_EXT */)
&& (v1_window_size < 32768 /* 32k */)
) {
bt_proto = ndpi_strnstr((const char *)&packet->payload[20], "BitTorrent protocol", packet->payload_packet_len-20);
goto bittorrent_found;
} else if((v0_flags < 6 /* ST_NUM_STATES */) && (v0_extension < 3 /* EXT_NUM_EXT */)) {
u_int32_t ts = ntohl(*((u_int32_t*)&(packet->payload[4])));
u_int32_t now;
now = (u_int32_t)time(NULL);
if((ts < (now+86400)) && (ts > (now-86400))) {
bt_proto = ndpi_strnstr((const char *)&packet->payload[20], "BitTorrent protocol", packet->payload_packet_len-20);
goto bittorrent_found;
}
}
}
}
flow->bittorrent_stage++;
if(flow->bittorrent_stage < 10) {
/* We have detected bittorrent but we need to wait until we get a hash */
if(packet->payload_packet_len > 19 /* min size */) {
if(ndpi_strnstr((const char *)packet->payload, ":target20:", packet->payload_packet_len)
|| ndpi_strnstr((const char *)packet->payload, ":find_node1:", packet->payload_packet_len)
|| ndpi_strnstr((const char *)packet->payload, "d1:ad2:id20:", packet->payload_packet_len)
|| ndpi_strnstr((const char *)packet->payload, ":info_hash20:", packet->payload_packet_len)
|| ndpi_strnstr((const char *)packet->payload, ":filter64", packet->payload_packet_len)
|| ndpi_strnstr((const char *)packet->payload, "d1:rd2:id20:", packet->payload_packet_len)
|| (bt_proto = ndpi_strnstr((const char *)packet->payload, "BitTorrent protocol", packet->payload_packet_len))
) {
bittorrent_found:
if(bt_proto && (packet->payload_packet_len > 47))
memcpy(flow->protos.bittorrent.hash, &bt_proto[27], 20);
NDPI_LOG_INFO(ndpi_struct, "found BT: plain\n");
ndpi_add_connection_as_bittorrent(ndpi_struct, flow, -1, 0,
NDPI_PROTOCOL_SAFE_DETECTION, NDPI_PROTOCOL_PLAIN_DETECTION);
return;
}
}
return;
}
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
}
}
void init_bittorrent_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask)
{
ndpi_set_bitmask_protocol_detection("BitTorrent", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_BITTORRENT,
ndpi_search_bittorrent,
NDPI_SELECTION_BITMASK_PROTOCOL_TCP_OR_UDP,
SAVE_DETECTION_BITMASK_AS_UNKNOWN,
ADD_TO_DETECTION_BITMASK);
*id += 1;
}