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fix(mdns): Fix to keep TXT/SRV in answers to queries #958

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fix(mdns): Fix to keep TXT/SRV in answers to queries #958

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29 changes: 28 additions & 1 deletion components/mdns/mdns.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1791,7 +1791,21 @@ static bool _mdns_create_answer_from_service(mdns_tx_packet_t *packet, mdns_serv
{
mdns_host_item_t *host = mdns_get_host_item(service->hostname);
bool is_delegated = (host != &_mdns_self_host);
if (question->type == MDNS_TYPE_PTR || question->type == MDNS_TYPE_ANY) {
bool is_instance_question = !_str_null_or_empty(question->host);
bool is_any_instance_question = (question->type == MDNS_TYPE_ANY) && is_instance_question;

/*
* Treat pure service-browse questions (PTR, or ANY without an instance label)
* as discovery: PTR in the Answer section, SRV/TXT (and address records) in
* the Additional section, per RFC 6763 section 12.1 and the Thread cert
* expectations.
*
* For instance-specific ANY questions (QNAME == instance._service._proto.local),
* behave more like a direct SRV/TXT query: put SRV/TXT in the Answer section
* and only addresses in the Additional section. This keeps Bonjour-style
* Q/A semantics while preserving the desired discovery behaviour.
*/
if (question->type == MDNS_TYPE_PTR || (question->type == MDNS_TYPE_ANY && !is_instance_question)) {
// According to RFC6763-section12.1, for DNS-SD, SRV, TXT and all address records
// should be included in additional records.
if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_PTR, service, NULL, false, false) ||
Expand All @@ -1803,6 +1817,19 @@ static bool _mdns_create_answer_from_service(mdns_tx_packet_t *packet, mdns_serv
send_flush, false)) {
return false;
}
} else if (is_any_instance_question) {
/*
* Instance-level ANY query: answer primarily with the SRV and TXT records
* for that specific instance, and place address records in the Additional
* section. This avoids returning unrelated PTRs in the Answer section for
* instance Q/A tests, which Bonjour Conformance Test is sensitive to.
*/
if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_SRV, service, NULL, send_flush, false) ||
!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_TXT, service, NULL, send_flush, false) ||
!_mdns_alloc_answer(&packet->additional, MDNS_TYPE_A, service, host, send_flush, false) ||
!_mdns_alloc_answer(&packet->additional, MDNS_TYPE_AAAA, service, host, send_flush, false)) {
return false;
}
} else if (question->type == MDNS_TYPE_SRV) {
if (!_mdns_alloc_answer(&packet->answers, MDNS_TYPE_SRV, service, NULL, send_flush, false) ||
!_mdns_alloc_answer(&packet->additional, MDNS_TYPE_A, service, host, send_flush, false) ||
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