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don't crash on rDNS failure

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Node apparently throws even on valid ipv6 input in certain environments,
probably due to the DNS server returning SERVFAIL.
Guard against it and fallback with the plain IP

Fixes: https://github.com/thelounge/thelounge/issues/4768
This commit is contained in:
Reto Brunner 2023-11-03 20:40:56 +01:00
parent f999db99c7
commit 8c54cd50d8
1 changed files with 30 additions and 18 deletions
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48
server/server.ts
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@ -1015,28 +1015,40 @@ function performAuthentication(this: Socket, data) {
}
function reverseDnsLookup(ip: string, callback: (hostname: string) => void) {
dns.reverse(ip, (reverseErr, hostnames) => {
if (reverseErr || hostnames.length < 1) {
return callback(ip);
}
dns.resolve(hostnames[0], net.isIP(ip) === 6 ? "AAAA" : "A", (resolveErr, resolvedIps) => {
// TODO: investigate SoaRecord class
if (!Array.isArray(resolvedIps)) {
// node can throw, even if we provide valid input based on the DNS server
// returning SERVFAIL it seems: https://github.com/thelounge/thelounge/issues/4768
// so we manually resolve with the ip as a fallback in case something fails
try {
dns.reverse(ip, (reverseErr, hostnames) => {
if (reverseErr || hostnames.length < 1) {
return callback(ip);
}
if (resolveErr || resolvedIps.length < 1) {
return callback(ip);
}
dns.resolve(
hostnames[0],
net.isIP(ip) === 6 ? "AAAA" : "A",
(resolveErr, resolvedIps) => {
// TODO: investigate SoaRecord class
if (!Array.isArray(resolvedIps)) {
return callback(ip);
}
for (const resolvedIp of resolvedIps) {
if (ip === resolvedIp) {
return callback(hostnames[0]);
if (resolveErr || resolvedIps.length < 1) {
return callback(ip);
}
for (const resolvedIp of resolvedIps) {
if (ip === resolvedIp) {
return callback(hostnames[0]);
}
}
return callback(ip);
}
}
return callback(ip);
);
});
});
} catch (err) {
log.error(`failed to resolve rDNS for ${ip}, using ip instead`, (err as any).toString());
setImmediate(callback, ip); // makes sure we always behave asynchronously
}
}