diff options
| -rw-r--r-- | src/resolve/resolved-mdns.c | 59 |
1 files changed, 58 insertions, 1 deletions
diff --git a/src/resolve/resolved-mdns.c b/src/resolve/resolved-mdns.c index 6767706f6e..096a4b1fe5 100644 --- a/src/resolve/resolved-mdns.c +++ b/src/resolve/resolved-mdns.c @@ -70,7 +70,64 @@ eaddrinuse: } static int on_mdns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { - /* TODO */ + _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; + Manager *m = userdata; + DnsScope *scope; + int r; + + r = manager_recv(m, fd, DNS_PROTOCOL_MDNS, &p); + if (r <= 0) + return r; + + scope = manager_find_scope(m, p); + if (!scope) { + log_warning("Got mDNS UDP packet on unknown scope. Ignoring."); + return 0; + } + + if (dns_packet_validate_reply(p) > 0) { + unsigned i; + + log_debug("Got mDNS reply packet"); + + /* + * mDNS is different from regular DNS and LLMNR with regard to handling responses. + * While on other protocols, we can ignore every answer that doesn't match a question + * we broadcast earlier, RFC6762, section 18.1 recommends looking at and caching all + * incoming information, regardless of the DNS packet ID. + * + * Hence, extract the packet here, and try to find a transaction for answer the we got + * and complete it. Also store the new information in scope's cache. + */ + r = dns_packet_extract(p); + if (r < 0) { + log_debug("mDNS packet extraction failed."); + return 0; + } + + dns_scope_check_conflicts(scope, p); + + for (i = 0; i < p->answer->n_rrs; i++) { + DnsResourceRecord *rr; + DnsTransaction *t; + + rr = p->answer->items[i].rr; + + t = dns_scope_find_transaction(scope, rr->key, false); + if (t) + dns_transaction_process_reply(t, p); + } + + dns_cache_put(&scope->cache, NULL, DNS_PACKET_RCODE(p), p->answer, + p->answer->n_rrs, false, 0, p->family, &p->sender); + + } else if (dns_packet_validate_query(p) > 0) { + log_debug("Got mDNS query packet for id %u", DNS_PACKET_ID(p)); + + dns_scope_process_query(scope, NULL, p); + } else + log_debug("Invalid mDNS UDP packet."); + return 0; } |