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Add NAPTR support for RFC 3263 compliant DNS resolution #163

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180 changes: 149 additions & 31 deletions sip.js
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Original file line number Diff line number Diff line change
Expand Up @@ -886,6 +886,15 @@ function makeWellBehavingResolver(resolve) {
var resolveSrv = makeWellBehavingResolver(dns.resolveSrv);
var resolve4 = makeWellBehavingResolver(dns.resolve4);
var resolve6 = makeWellBehavingResolver(dns.resolve6);
var resolveNaptr = makeWellBehavingResolver(dns.resolveNaptr);

// NAPTR service to protocol mapping per RFC 3263
var naptrServices = {
'SIP+D2T': 'tcp', // SIP over TCP
'SIP+D2U': 'udp', // SIP over UDP
'SIP+D2S': 'sctp', // SIP over SCTP
'SIPS+D2T': 'tls' // SIP over TLS
};

function resolve(uri, action) {
if(uri.params.transport === 'ws')
Expand Down Expand Up @@ -917,41 +926,150 @@ function resolve(uri, action) {
});
}
else {
var protocols = uri.params.transport ? [uri.params.transport] : ['tcp', 'udp', 'tls'];

var n = protocols.length;
var addresses = [];

protocols.forEach(function(proto) {
resolveSrv('_sip._'+proto+'.'+uri.host, function(e, r) {
--n;

if(Array.isArray(r)) {
n += r.length;
r.forEach(function(srv) {
resolve46(srv.name, function(e, r) {
addresses = addresses.concat((r||[]).map(function(a) { return {protocol: proto, address: a, port: srv.port};}));

if((--n)===0) // all outstanding requests has completed
action(addresses);
// Helper function to resolve SRV records for given protocols (existing behavior)
function resolveSrvForProtocols(protocols, host, callback) {
var n = protocols.length;
var addresses = [];

protocols.forEach(function(proto) {
resolveSrv('_sip._'+proto+'.'+host, function(e, r) {
--n;

if(Array.isArray(r)) {
n += r.length;
r.forEach(function(srv) {
resolve46(srv.name, function(e, r) {
addresses = addresses.concat((r||[]).map(function(a) { return {protocol: proto, address: a, port: srv.port};}));

if((--n)===0) // all outstanding requests have completed
callback(addresses);
});
});
});
}
else if(0 === n) {
if(addresses.length) {
action(addresses);
}
else {
// all srv requests failed
resolve46(uri.host, function(err, address) {
address = (address || []).map(function(x) { return protocols.map(function(p) { return { protocol: p, address: x, port: uri.port || defaultPort(p)};});})
.reduce(function(arr,v) { return arr.concat(v); }, []);
action(address);
});
else if(0 === n) {
if(addresses.length) {
callback(addresses);
}
else {
// all srv requests failed, fallback to A/AAAA
resolve46(host, function(err, address) {
address = (address || []).map(function(x) { return protocols.map(function(p) { return { protocol: p, address: x, port: defaultPort(p)};});})
.reduce(function(arr,v) { return arr.concat(v); }, []);
callback(address);
});
}
}
});
});
}

// Helper function to resolve addresses from NAPTR records
function resolveFromNaptr(naptrRecords, callback) {
// Sort NAPTR records by order, then by preference (lower values = higher priority)
naptrRecords.sort(function(a, b) {
return (a.order - b.order) || (a.preference - b.preference);
});

// Filter for SIP-related services and extract protocol info
var sipRecords = naptrRecords.filter(function(r) {
return naptrServices[r.service];
});

if(sipRecords.length === 0) {
return callback(null); // No SIP NAPTR records, trigger fallback
}

var addresses = [];
var pending = sipRecords.length;

sipRecords.forEach(function(naptr) {
var proto = naptrServices[naptr.service];
var flags = (naptr.flags || '').toLowerCase();

if(flags === 's') {
// 's' flag: replacement is an SRV target
resolveSrv(naptr.replacement, function(e, srvRecords) {
if(Array.isArray(srvRecords) && srvRecords.length > 0) {
var srvPending = srvRecords.length;
srvRecords.forEach(function(srv) {
resolve46(srv.name, function(e, addrs) {
addresses = addresses.concat((addrs||[]).map(function(a) {
return {protocol: proto, address: a, port: srv.port, order: naptr.order, preference: naptr.preference};
}));
if(--srvPending === 0 && --pending === 0) {
finalize();
}
});
});
} else {
if(--pending === 0) finalize();
}
});
} else if(flags === 'a') {
// 'a' flag: replacement is a hostname for A/AAAA lookup
resolve46(naptr.replacement, function(e, addrs) {
addresses = addresses.concat((addrs||[]).map(function(a) {
return {protocol: proto, address: a, port: defaultPort(proto), order: naptr.order, preference: naptr.preference};
}));
if(--pending === 0) finalize();
});
} else {
// Empty or unknown flags: treat replacement as SRV target (common case)
resolveSrv(naptr.replacement, function(e, srvRecords) {
if(Array.isArray(srvRecords) && srvRecords.length > 0) {
var srvPending = srvRecords.length;
srvRecords.forEach(function(srv) {
resolve46(srv.name, function(e, addrs) {
addresses = addresses.concat((addrs||[]).map(function(a) {
return {protocol: proto, address: a, port: srv.port, order: naptr.order, preference: naptr.preference};
}));
if(--srvPending === 0 && --pending === 0) {
finalize();
}
});
});
} else {
if(--pending === 0) finalize();
}
});
}
})
});
});

function finalize() {
// Sort final addresses by NAPTR order/preference
addresses.sort(function(a, b) {
return (a.order - b.order) || (a.preference - b.preference);
});
// Remove order/preference from final result
addresses = addresses.map(function(a) {
return {protocol: a.protocol, address: a.address, port: a.port};
});
callback(addresses);
}
}

// If transport is explicitly specified, skip NAPTR and use SRV directly
if(uri.params.transport) {
resolveSrvForProtocols([uri.params.transport], uri.host, action);
}
else {
// RFC 3263: Try NAPTR first, then fall back to SRV
resolveNaptr(uri.host, function(err, naptrRecords) {
if(naptrRecords && naptrRecords.length > 0) {
resolveFromNaptr(naptrRecords, function(addresses) {
if(addresses && addresses.length > 0) {
action(addresses);
} else {
// NAPTR records existed but yielded no addresses, fall back to SRV
resolveSrvForProtocols(['tcp', 'udp', 'tls'], uri.host, action);
}
});
} else {
// No NAPTR records, fall back to SRV queries
resolveSrvForProtocols(['tcp', 'udp', 'tls'], uri.host, action);
}
});
}
}
}

Expand Down