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mdns: fix mDNS peer discovery on systems without getaddrinfo mDNS resolution #1019

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Merged
pkova merged 1 commit into from
Jul 6, 2026
Merged

mdns: fix mDNS peer discovery on systems without getaddrinfo mDNS resolution #1019

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100 changes: 63 additions & 37 deletions pkg/vere/mdns.c
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Original file line number Diff line number Diff line change
Expand Up @@ -26,20 +26,53 @@ static void close_cb(uv_handle_t* poll) {
c3_free(payload);
}

static void getaddrinfo_cb(uv_getaddrinfo_t* req, int status, struct addrinfo* res) {
mdns_payload* payload = (mdns_payload*)req->data;
static void poll_cb(uv_poll_t* handle, int status, int events) {
mdns_payload* payload = (mdns_payload*) handle->data;
int err = DNSServiceProcessResult(payload->sref);
}

if (status < 0) {
u3l_log("mdns: getaddrinfo error: %s", uv_strerror(status));
} else {
struct sockaddr_in* addr = (struct sockaddr_in*)res->ai_addr;
payload->cb(payload->who, payload->fake, addr->sin_addr.s_addr, payload->port, payload->context);
static void init_sref_poll(mdns_payload* payload) {
int fd = DNSServiceRefSockFD(payload->sref);
uv_loop_t* loop = uv_default_loop();
payload->poll.data = (void*)payload;
uv_poll_init(loop, &payload->poll, fd);
uv_poll_start(&payload->poll, UV_READABLE, poll_cb);
}

static void query_record_cb(DNSServiceRef sref,
DNSServiceFlags f,
uint32_t iface,
DNSServiceErrorType err,
const char *fullname,
uint16_t rrtype,
uint16_t rrclass,
uint16_t rdlen,
const void *rdata,
uint32_t ttl,
void *context)
{
mdns_payload* payload = (mdns_payload*)context;

uv_poll_stop(&payload->poll);

if (err != kDNSServiceErr_NoError) {
u3l_log("mdns: dns query error %d", err);
}
else if ( (kDNSServiceType_A != rrtype) ||
(kDNSServiceClass_IN != rrclass) ||
(4 != rdlen) ||
(0 == (f & kDNSServiceFlagsAdd)) ) {
u3l_log("mdns: unexpected A record response for %s", payload->who);
}
else {
c3_w saddr_w;

memcpy(&saddr_w, rdata, sizeof(saddr_w));
payload->cb(payload->who, payload->fake, saddr_w, payload->port, payload->context);
}

payload->poll.data = payload;
uv_close((uv_handle_t*)&payload->poll, close_cb);
c3_free(req);
uv_freeaddrinfo(res);
}

static void resolve_cb(DNSServiceRef sref,
Expand Down Expand Up @@ -81,37 +114,30 @@ static void resolve_cb(DNSServiceRef sref,
payload->who[i+1] = start[i];
}

struct addrinfo hints;
memset(&hints, 0, sizeof(hints));
hints.ai_family = AF_INET; // Request only IPv4 addresses
hints.ai_socktype = SOCK_STREAM; // TCP socket

uv_getaddrinfo_t* req = (uv_getaddrinfo_t*)c3_calloc(sizeof(uv_getaddrinfo_t));
req->data = (void*)payload;

uv_loop_t* loop = uv_default_loop();

int error = uv_getaddrinfo(loop, req, getaddrinfo_cb, host, NULL, &hints);

if (error < 0) {
u3l_log("mdns: getaddrinfo error: %s\n", uv_strerror(error));
payload->poll.data = payload;
uv_close((uv_handle_t*)&payload->poll, close_cb);
c3_free(req);
mdns_payload* query_payload = c3_calloc(sizeof *query_payload);
memcpy(query_payload, payload, sizeof(*query_payload));

DNSServiceErrorType query_err =
DNSServiceQueryRecord(&query_payload->sref,
0,
iface,
host,
kDNSServiceType_A,
kDNSServiceClass_IN,
query_record_cb,
(void*)query_payload);

if (query_err != kDNSServiceErr_NoError) {
u3l_log("mdns: dns A query error %d", query_err);
c3_free(query_payload);
}
}

static void poll_cb(uv_poll_t* handle, int status, int events) {
mdns_payload* payload = (mdns_payload*) handle->data;
int err = DNSServiceProcessResult(payload->sref);
}
payload->poll.data = payload;
uv_close((uv_handle_t*)&payload->poll, close_cb);

static void init_sref_poll(mdns_payload* payload) {
int fd = DNSServiceRefSockFD(payload->sref);
uv_loop_t* loop = uv_default_loop();
payload->poll.data = (void*)payload;
uv_poll_init(loop, &payload->poll, fd);
uv_poll_start(&payload->poll, UV_READABLE, poll_cb);
if (query_err == kDNSServiceErr_NoError) {
init_sref_poll(query_payload);
}
}

static void browse_cb(DNSServiceRef s,
Expand Down
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