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dns: fix Windows SRV ECONNREFUSED regression by correcting c-ares fallback detection #61453

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dns: fix Windows SRV ECONNREFUSED regression by correcting c-ares fallback detection #61453

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7914dcd
fix fix Windows SRV ECONNREFUSED regression
NotVivek12 Jan 20, 2026
0683f48
Merge branch 'main' of https://github.com/NotVivek12/node
NotVivek12 Jan 20, 2026
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27 changes: 21 additions & 6 deletions src/cares_wrap.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -983,19 +983,30 @@ void ChannelWrap::EnsureServers() {

ares_get_servers_ports(channel_, &servers);

/* if no server or multi-servers, ignore */
/* if no server, ignore */
if (servers == nullptr) return;

/* if multi-servers, mark as non-default and ignore */
if (servers->next != nullptr) {
ares_free_data(servers);
is_servers_default_ = false;
return;
}

/* if the only server is not 127.0.0.1, ignore */
if (servers[0].family != AF_INET ||
servers[0].addr.addr4.s_addr != htonl(INADDR_LOOPBACK) ||
servers[0].tcp_port != 0 ||
servers[0].udp_port != 0) {
/* Check if the only server is a loopback address (IPv4 127.0.0.1 or IPv6 ::1).
* Newer c-ares versions may set tcp_port/udp_port to 53 instead of 0,
* so we no longer check port values. */
bool is_loopback = false;
if (servers[0].family == AF_INET) {
is_loopback = (servers[0].addr.addr4.s_addr == htonl(INADDR_LOOPBACK));
} else if (servers[0].family == AF_INET6) {
static const unsigned char kIPv6Loopback[16] =
{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1};
is_loopback =
(memcmp(&servers[0].addr.addr6, kIPv6Loopback, sizeof(kIPv6Loopback)) == 0);
}

if (!is_loopback) {
ares_free_data(servers);
is_servers_default_ = false;
return;
Expand Down Expand Up @@ -1769,6 +1780,10 @@ static void Query(const FunctionCallbackInfo<Value>& args) {
node::Utf8Value utf8name(args.GetIsolate(), string);
auto plain_name = utf8name.ToStringView();
std::string name = ada::idna::to_ascii(plain_name);

// Ensure c-ares did not fall back to loopback resolver.
channel->EnsureServers();

channel->ModifyActivityQueryCount(1);
int err = wrap->Send(name.c_str());
if (err) {
Expand Down