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Diffstat (limited to 'src/lib/protocols/mdns_proto.c')
| -rw-r--r-- | src/lib/protocols/mdns_proto.c | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/src/lib/protocols/mdns_proto.c b/src/lib/protocols/mdns_proto.c new file mode 100644 index 000000000..77bdf4208 --- /dev/null +++ b/src/lib/protocols/mdns_proto.c @@ -0,0 +1,159 @@ +/* + * mdns.c + * + * Copyright (C) 2016-18 - 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_MDNS + +#include "ndpi_api.h" + +#define NDPI_MAX_MDNS_REQUESTS 128 + +PACK_ON +struct mdns_header { + u_int16_t transaction_id, flags, questions, answers, authority_rr, additional_rr; +} PACK_OFF; + +/** + MDNS header is similar to dns header + + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | ID = 0x0000 | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | FLAGS | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | QDCOUNT | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | ANCOUNT | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | NSCOUNT | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | ARCOUNT | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ +*/ + + +static void ndpi_int_mdns_add_connection(struct ndpi_detection_module_struct + *ndpi_struct, struct ndpi_flow_struct *flow) { + ndpi_set_detected_protocol(ndpi_struct, flow, NDPI_PROTOCOL_MDNS, NDPI_PROTOCOL_UNKNOWN); +} + +static int ndpi_int_check_mdns_payload(struct ndpi_detection_module_struct + *ndpi_struct, struct ndpi_flow_struct *flow) { + struct ndpi_packet_struct *packet = &flow->packet; + struct mdns_header *h = (struct mdns_header*)packet->payload; + u_int16_t questions = ntohs(h->questions), answers = ntohs(h->answers); + + if(((packet->payload[2] & 0x80) == 0) + && (questions <= NDPI_MAX_MDNS_REQUESTS) + && (answers <= NDPI_MAX_MDNS_REQUESTS)) { + NDPI_LOG_INFO(ndpi_struct, "found MDNS with question query\n"); + return 1; + } + else if(((packet->payload[2] & 0x80) != 0) + && (questions == 0) + && (answers <= NDPI_MAX_MDNS_REQUESTS) + && (answers != 0)) { + char answer[256]; + int i, j, len; + + for(i=13, j=0; (packet->payload[i] != 0) && (i < packet->payload_packet_len) && (i < (sizeof(answer)-1)); i++) + answer[j++] = (packet->payload[i] < 13) ? '.' : packet->payload[i]; + + answer[j] = '\0'; + + /* printf("==> [%d] %s\n", j, answer); */ + + if(!ndpi_struct->disable_metadata_export) { + len = ndpi_min(sizeof(flow->protos.mdns.answer)-1, j); + strncpy(flow->protos.mdns.answer, (const char *)answer, len); + flow->protos.mdns.answer[len] = '\0'; + } + + NDPI_LOG_INFO(ndpi_struct, "found MDNS with answer query\n"); + return 1; + } + + return 0; +} + +void ndpi_search_mdns(struct ndpi_detection_module_struct *ndpi_struct, struct ndpi_flow_struct *flow) +{ + struct ndpi_packet_struct *packet = &flow->packet; + u_int16_t dport; + + NDPI_LOG_DBG(ndpi_struct, "search MDNS\n"); + + /** + information from http://www.it-administrator.de/lexikon/multicast-dns.html + */ + + /* check if UDP packet */ + if(packet->udp != NULL) { + /* read destination port */ + dport = ntohs(packet->udp->dest); + + /* check standard MDNS ON port 5353 */ + if(dport == 5353 && packet->payload_packet_len >= 12) { + /* mdns protocol must have destination address 224.0.0.251 */ + if(packet->iph != NULL /* && ntohl(packet->iph->daddr) == 0xe00000fb */) { + + NDPI_LOG_INFO(ndpi_struct, "found MDNS with destination address 224.0.0.251 (=0xe00000fb)\n"); + + if(ndpi_int_check_mdns_payload(ndpi_struct, flow) == 1) { + ndpi_int_mdns_add_connection(ndpi_struct, flow); + return; + } + } +#ifdef NDPI_DETECTION_SUPPORT_IPV6 + if(packet->iphv6 != NULL) { + const u_int32_t *daddr = packet->iphv6->ip6_dst.u6_addr.u6_addr32; + if(daddr[0] == htonl(0xff020000) /* && daddr[1] == 0 && daddr[2] == 0 && daddr[3] == htonl(0xfb) */) { + + NDPI_LOG_INFO(ndpi_struct, "found MDNS with destination address ff02::fb\n"); + + if(ndpi_int_check_mdns_payload(ndpi_struct, flow) == 1) { + ndpi_int_mdns_add_connection(ndpi_struct, flow); + return; + } + } + } +#endif + } + } + NDPI_EXCLUDE_PROTO(ndpi_struct, flow); +} + + +void init_mdns_dissector(struct ndpi_detection_module_struct *ndpi_struct, u_int32_t *id, NDPI_PROTOCOL_BITMASK *detection_bitmask) +{ + ndpi_set_bitmask_protocol_detection("MDNS", ndpi_struct, detection_bitmask, *id, + NDPI_PROTOCOL_MDNS, + ndpi_search_mdns, + NDPI_SELECTION_BITMASK_PROTOCOL_V4_V6_UDP_WITH_PAYLOAD, + SAVE_DETECTION_BITMASK_AS_UNKNOWN, + ADD_TO_DETECTION_BITMASK); + + *id += 1; +} + |