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mdns: add simple dns-sd meta query support

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negativekelvin 2017-02-13 21:53:46 -07:00 committed by Angus Gratton
parent 8ee6f8227e
commit 96e8a3c725
1 changed files with 68 additions and 0 deletions
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68
components/mdns/mdns.c
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@ -46,6 +46,7 @@
#define MDNS_ANSWER_A 0x01
#define MDNS_ANSWER_AAAA 0x10
#define MDNS_ANSWER_NSEC 0x20
#define MDNS_ANSWER_SDPTR 0x80
#define MDNS_SERVICE_PORT 5353 // UDP port that the server runs on
#define MDNS_SERVICE_STACK_DEPTH 4096 // Stack size for the service thread
@ -796,6 +797,52 @@ static uint16_t _mdns_append_ptr_record(uint8_t * packet, uint16_t * index, mdns
return record_length;
}
/**
* @brief appends DNS-SD PTR record for service to a packet, incrementing the index
*
* @param packet MDNS packet
* @param index offset in the packet
* @param server the server that is hosting the service
* @param service the service to add record for
*
* @return length of added data: 0 on error or length on success
*/
static uint16_t _mdns_append_sdptr_record(uint8_t * packet, uint16_t * index, mdns_server_t * server, mdns_service_t * service)
{
const char * str[3];
const char * sd_str[4];
uint16_t record_length = 0;
uint8_t part_length;
sd_str[0] = (char*)"_services";
sd_str[1] = (char*)"_dns-sd";
sd_str[2] = (char*)"_udp";
sd_str[3] = MDNS_DEFAULT_DOMAIN;
str[0] = service->service;
str[1] = service->proto;
str[2] = MDNS_DEFAULT_DOMAIN;
part_length = _mdns_append_fqdn(packet, index, sd_str, 4);
record_length += part_length;
part_length = _mdns_append_type(packet, index, MDNS_ANSWER_PTR, MDNS_ANSWER_PTR_TTL);
if (!part_length) {
return 0;
}
record_length += part_length;
uint16_t data_len_location = *index - 2;
part_length = _mdns_append_fqdn(packet, index, str, 3);
if (!part_length) {
return 0;
}
_mdns_set_u16(packet, data_len_location, part_length);
record_length += part_length;
return record_length;
}
/**
* @brief appends TXT record for service to a packet, incrementing the index
*
@ -1042,6 +1089,13 @@ static void _mdns_send_answers(mdns_server_t * server, mdns_answer_item_t * answ
}
answer_count += 1;
}
if (answers->answer & MDNS_ANSWER_SDPTR) {
if (!_mdns_append_sdptr_record(packet, &index, server, answers->service)) {
return;
}
answer_count += 1;
}
}
mdns_answer_item_t * a = answers;
answers = answers->next;
@ -1274,6 +1328,20 @@ static void _mdns_parse_packet(mdns_server_t * server, const uint8_t * data, siz
}
continue;
}
//is this a dns-sd service discovery meta query?
if (!strcmp(name->host, "_services") && !strcmp(name->service, "_dns-sd") && !strcmp(name->proto, "_udp") && !strcmp(name->domain, MDNS_DEFAULT_DOMAIN) && type == MDNS_TYPE_PTR)
{
//add answers for all services
mdns_srv_item_t * s = server->services;
while(s) {
if (s->service->service && s->service->proto) {
answers = _mdns_add_answer(answers, s->service, MDNS_ANSWER_SDPTR);
}
s = s->next;
}
continue;
}
if (name->sub) {
continue;