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/*
* fbzero.c
*
* Copyright (C) 2018 - ntop.org
*
* 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"
/* https://code.facebook.com/posts/608854979307125/building-zero-protocol-for-fast-secure-mobile-connections/ */
#define NDPI_CURRENT_PROTO NDPI_PROTOCOL_FBZERO
#include "ndpi_api.h"
PACK_ON
struct fbzero_tag {
char tag[4];
u_int32_t tag_offset_len;
} PACK_OFF;
PACK_ON
struct fbzero_header {
u_int8_t flags;
char version[3];
u_int8_t unknown;
u_int32_t len;
char tag[4];
u_int16_t tag_number, _pad;
} PACK_OFF;
/* **************************************************************************** */
void ndpi_search_fbzero(struct ndpi_detection_module_struct *ndpi_struct,
struct ndpi_flow_struct *flow) {
struct ndpi_packet_struct *packet = &flow->packet;
NDPI_LOG_DBG(ndpi_struct, "search FacebookZero\n");
if(packet->payload_packet_len > sizeof(struct fbzero_header)) {
struct fbzero_header *h = (struct fbzero_header*)packet->payload;
struct fbzero_tag *t;
u_int offset = sizeof(struct fbzero_header), i, data_offset, tag_number, data_prev_offset = 0;
if((h->flags & 0x01) == 0)
goto fbzero_not_found;
if((h->version[0] != 'Q')
|| (h->version[1] != 'T')
|| (h->version[2] != 'V'))
goto fbzero_not_found;
if(h->unknown != 0x30)
goto fbzero_not_found;
t = (struct fbzero_tag*)&packet->payload[offset];
tag_number = h->tag_number;
data_offset = offset + tag_number*sizeof(struct fbzero_tag);
if(strncmp(h->tag, "CHLO", 4))
goto fbzero_not_found;
for(i=0; i<h->tag_number; i++) {
#ifdef DEBUG
printf("[FBZERO] %u) %c%c%c%c\n", i, t->tag[0], t->tag[1], t->tag[2], t->tag[3]);
#endif
offset += sizeof(struct fbzero_tag);
if((t->tag[0] == 'S') && (t->tag[1] == 'N')
&& (t->tag[2] == 'I') && (t->tag[3] == '\0')) {
char *value = (char*)&packet->payload[data_offset + data_prev_offset];
u_int tag_len = t->tag_offset_len-data_prev_offset, max_len;
max_len = ndpi_min(tag_len, sizeof(flow->host_server_name)-1);
strncpy((char*)flow->host_server_name, value, max_len);
flow->host_server_name[max_len] = '\0';
#ifdef DEBUG
printf("[FBZERO] SNI [@%u][len: %u][%s]\n", tag_len,
t->tag_offset_len-data_prev_offset, flow->host_server_name);
#endif
ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_FBZERO, NDPI_PROTOCOL_UNKNOWN);
ndpi_match_host_subprotocol(ndpi_struct, flow, (char *)flow->host_server_name,
strlen((const char *)flow->host_server_name),
NDPI_PROTOCOL_FBZERO);
return;
}
data_prev_offset = t->tag_offset_len;
t = (struct fbzero_tag*)&packet->payload[offset];
}
return;
}
fbzero_not_found:
NDPI_EXCLUDE_PROTO(ndpi_struct, flow);
}
/* **************************************************************************** */
void init_fbzero_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id,
NDPI_PROTOCOL_BITMASK *detection_bitmask) {
ndpi_set_bitmask_protocol_detection("FacebookZero", ndpi_struct, detection_bitmask, *id,
NDPI_PROTOCOL_FBZERO,
ndpi_search_fbzero,
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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