diff options
| author | Ivan Nardi <12729895+IvanNardi@users.noreply.github.com> | 2023-07-31 07:44:43 +0200 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2023-07-31 07:44:43 +0200 |
| commit | 5019022e13ac1f807d818ab4c8d6aafc1bd7d66d (patch) | |
| tree | f05b991e4ba97b505f25c1cc10ac959d75df96c3 /src | |
| parent | d477da997fb3326104037db02094f80f5e5cbe11 (diff) | |
DNS: extract geolocation information, if available (#2065)
The option NSID (RFC5001) is used by Google DNS to report the
airport code of the metro where the DNS query is handled.
This option is quite rare, but the added overhead in DNS code is pretty
much zero for "normal" DNS traffic
Diffstat (limited to 'src')
| -rw-r--r-- | src/include/ndpi_typedefs.h | 1 | ||||
| -rw-r--r-- | src/lib/protocols/dns.c | 31 |
2 files changed, 31 insertions, 1 deletions
diff --git a/src/include/ndpi_typedefs.h b/src/include/ndpi_typedefs.h index f56fdab8f..15415526c 100644 --- a/src/include/ndpi_typedefs.h +++ b/src/include/ndpi_typedefs.h @@ -1486,6 +1486,7 @@ struct ndpi_flow_struct { u_int8_t num_queries, num_answers, reply_code, is_query; u_int16_t query_type, query_class, rsp_type, edns0_udp_payload_size; ndpi_ip_addr_t rsp_addr; /* The first address in a DNS response packet (A and AAAA) */ + char geolocation_iata_code[4]; char ptr_domain_name[64 /* large enough but smaller than { } tls */]; } dns; diff --git a/src/lib/protocols/dns.c b/src/lib/protocols/dns.c index 6e4864405..07358468d 100644 --- a/src/lib/protocols/dns.c +++ b/src/lib/protocols/dns.c @@ -547,7 +547,8 @@ static int search_valid_dns(struct ndpi_detection_module_struct *ndpi_struct, u_int16_t num; for(num = 0; num < dns_header->additional_rrs; num++) { - u_int16_t data_len; + u_int16_t data_len, rdata_len, opt_code, opt_len; + const unsigned char *opt; if((x+6) > packet->payload_packet_len) { break; @@ -576,6 +577,34 @@ static int search_valid_dns(struct ndpi_detection_module_struct *ndpi_struct, printf("[DNS] [response] edns0_udp_payload_size: %u\n", flow->protos.dns.edns0_udp_payload_size); #endif x += 6; + + rdata_len = ntohs(*((u_int16_t *)&packet->payload[x])); +#ifdef DNS_DEBUG + printf("[DNS] [response] rdata len: %u\n", rdata_len); +#endif + if(rdata_len > 0 && + x + 6 <= packet->payload_packet_len) { + opt_code = ntohs(*((u_int16_t *)&packet->payload[x + 2])); + opt_len = ntohs(*((u_int16_t *)&packet->payload[x + 4])); + opt = &packet->payload[x + 6]; + /* TODO: parse the TLV list */ + if(opt_code == 0x03 && + opt_len <= rdata_len + 4 && + opt_len > 6 && + x + 6 + opt_len <= packet->payload_packet_len) { +#ifdef DNS_DEBUG + printf("[DNS] NSID: [%.*s]\n", opt_len, opt); +#endif + if(memcmp(opt, "gpdns-", 6) == 0) { +#ifdef DNS_DEBUG + printf("[DNS] NSID Airport code [%.*s]\n", opt_len - 6, opt + 6); +#endif + memcpy(flow->protos.dns.geolocation_iata_code, opt + 6, + ndpi_min(opt_len - 6, (int)sizeof(flow->protos.dns.geolocation_iata_code) - 1)); + } + } + + } } else { x += 6; } |