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[dgram] only look up hostname for the requested address family
- [lib/dns.js] dns.lookup takes a new optional argument "family" which should be the integer 4, 6, dns.AF_INET or dns.AF_INET6. Passing a non-false "family" argument makes c-ares explicitly look up addresses for the specified family. - [test/simple/test-c-ares.js] test explicit address family lookups
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+107
-47
lines changed

3 files changed

+107
-47
lines changed

‎doc/api.markdown

+11
Original file line numberDiff line numberDiff line change
@@ -2515,6 +2515,17 @@ resolves the IP addresses which are returned.
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});
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});
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2518+
### dns.lookup(domain, family=null, callback)
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Resolves a domain (e.g. `'google.com'`) into the first found A (IPv4) or
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AAAA (IPv6) record.
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The callback has arguments `(err, address, family)`. The `address` argument
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is a string representation of a IP v4 or v6 address. The `family` argument
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is either the integer 4 or 6 and denotes the family of `address` (not
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neccessarily the value initially passed to `lookup`).
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25182529
### dns.resolve(domain, rrtype='A', callback)
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Resolves a domain (e.g. `'google.com'`) into an array of the record types

‎lib/dgram.js

+23-21
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,16 @@ function getPool() {
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return pool;
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}
3030

31+
function dnsLookup(type, hostname, callback) {
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var family = (type ? ((type === "udp6") ? 6 : 4) : null);
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dns.lookup(hostname, family, function (err, ip, addressFamily) {
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if (!err && family && addressFamily !== family) {
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err = new Error('no address found in family '+type+' for '+hostname);
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}
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callback(err, ip, addressFamily);
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});
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}
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3141
function Socket (type, listener) {
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events.EventEmitter.call(this);
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var self = this;
@@ -103,22 +113,15 @@ Socket.prototype.bind = function () {
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} else {
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// the first argument is the port, the second an address
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this.port = arguments[0];
106-
if (dns.isIP(arguments[1])) {
107-
this.address = arguments[1];
108-
binding.bind(self.fd, port, arguments[1]);
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this.emit("listening");
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} else {
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dns.lookup(arguments[1], function (err, ip, addressType) {
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// TODO - only look up proper record for address family
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if (err) {
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self.emit('error', err);
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} else {
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self.ip = ip;
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binding.bind(self.fd, self.port, ip);
118-
self.emit("listening");
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}
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});
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}
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dnsLookup(this.type, arguments[1], function (err, ip, addressFamily) {
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if (err) {
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self.emit('error', err);
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} else {
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self.ip = ip;
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binding.bind(self.fd, self.port, ip);
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self.emit("listening");
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}
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});
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}
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}
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};
@@ -153,7 +156,7 @@ Socket.prototype.setTTL = function(arg) {
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}
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};
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156-
// translate arguments from JS API into C++ API, after optional DNS lookup
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// translate arguments from JS API into C++ API, possibly after DNS lookup
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Socket.prototype.send = function(buffer, offset, length) {
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var self = this;
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@@ -173,13 +176,12 @@ Socket.prototype.send = function(buffer, offset, length) {
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}
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if (dns.isIP(arguments[4])) {
176-
self.sendto(arguments[0], arguments[1], arguments[2], arguments[3], arguments[4], arguments[5]);
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self.sendto(arguments[0], arguments[1], arguments[2], arguments[3],
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arguments[4], arguments[5]);
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} else {
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var port = arguments[3],
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callback = arguments[5];
180-
181-
// TODO - only look up proper record for address family
182-
dns.lookup(arguments[4], function (err, ip, addressType) {
184+
dnsLookup(this.type, arguments[4], function (err, ip, addressFamily) {
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if (err) { // DNS error
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if (callback) {
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callback(err);

‎lib/dns.js

+73-26
Original file line numberDiff line numberDiff line change
@@ -100,46 +100,93 @@ exports.getHostByName = function (domain, callback) {
100100
var net;
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102102
// Easy DNS A/AAAA look up
103-
exports.lookup = function (domain, callback) {
104-
var addressType = dns.isIP(domain);
105-
if (addressType) {
106-
process.nextTick(function () {
107-
callback(null, domain, addressType);
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});
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// lookup(domain, [family,] callback)
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exports.lookup = function (domain, family, callback) {
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if (arguments.length === 2) {
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callback = family;
107+
family = undefined;
108+
} else if (family && family !== 4 && family !== 6) {
109+
family = parseInt(family);
110+
if (family === dns.AF_INET) {
111+
family = 4;
112+
} else if (family === dns.AF_INET6) {
113+
family = 6;
114+
} else if (family !== 4 && family !== 6) {
115+
throw new Error('invalid argument: "family" must be 4 or 6');
116+
}
117+
}
118+
if (!domain) {
119+
callback(null, null, family === 6 ? 6 : 4);
120+
return;
121+
}
122+
var matchedFamily = dns.isIP(domain);
123+
if (matchedFamily) {
124+
callback(null, domain, matchedFamily);
109125
} else {
110-
if (/\w\.local\.?$/.test(domain) ) {
126+
if (/\w\.local\.?$/.test(domain)) {
111127
// ANNOYING: In the case of mDNS domains use NSS in the thread pool.
112128
// I wish c-ares had better support.
113129
process.binding('net').getaddrinfo(domain, 4, function (err, domains4) {
114130
callback(err, domains4[0], 4);
115131
});
116132
} else {
117-
channel.getHostByName(domain, dns.AF_INET, function (err, domains4) {
118-
if (domains4 && domains4.length) {
119-
callback(null, domains4[0], 4);
120-
} else {
121-
channel.getHostByName(domain, dns.AF_INET6, function (err, domains6) {
122-
if (domains6 && domains6.length) {
123-
callback(null, domains6[0], 6);
133+
if (family) {
134+
// resolve names for explicit address family
135+
var af = (family === 4) ? dns.AF_INET : dns.AF_INET6;
136+
channel.getHostByName(domain, af, function (err, domains) {
137+
if (!err && domains && domains.length) {
138+
if (family !== dns.isIP(domains[0])) {
139+
callback(new Error('not found'), []);
124140
} else {
125-
callback(err, []);
141+
callback(null, domains[0], family);
126142
}
127-
});
128-
}
129-
});
143+
} else {
144+
callback(err, []);
145+
}
146+
});
147+
} else {
148+
// first resolve names for v4 and if that fails, try v6
149+
channel.getHostByName(domain, dns.AF_INET, function (err, domains4) {
150+
if (domains4 && domains4.length) {
151+
callback(null, domains4[0], 4);
152+
} else {
153+
channel.getHostByName(domain, dns.AF_INET6,
154+
function (err, domains6) {
155+
if (domains6 && domains6.length) {
156+
callback(null, domains6[0], 6);
157+
} else {
158+
callback(err, []);
159+
}
160+
});
161+
}
162+
});
163+
}
130164
}
131165
}
132166
};
133167

134168

135-
exports.resolve4 = function(domain, callback) { channel.query(domain, dns.A, callback) };
136-
exports.resolve6 = function(domain, callback) { channel.query(domain, dns.AAAA, callback) };
137-
exports.resolveMx = function(domain, callback) { channel.query(domain, dns.MX, callback) };
138-
exports.resolveTxt = function(domain, callback) { channel.query(domain, dns.TXT, callback) };
139-
exports.resolveSrv = function(domain, callback) { channel.query(domain, dns.SRV, callback) };
140-
exports.reverse = function(domain, callback) { channel.query(domain, dns.PTR, callback) };
141-
exports.resolveNs = function(domain, callback) { channel.query(domain, dns.NS, callback) };
142-
169+
exports.resolve4 = function(domain, callback) {
170+
channel.query(domain, dns.A, callback);
171+
};
172+
exports.resolve6 = function(domain, callback) {
173+
channel.query(domain, dns.AAAA, callback);
174+
};
175+
exports.resolveMx = function(domain, callback) {
176+
channel.query(domain, dns.MX, callback);
177+
};
178+
exports.resolveTxt = function(domain, callback) {
179+
channel.query(domain, dns.TXT, callback);
180+
};
181+
exports.resolveSrv = function(domain, callback) {
182+
channel.query(domain, dns.SRV, callback);
183+
};
184+
exports.reverse = function(domain, callback) {
185+
channel.query(domain, dns.PTR, callback);
186+
};
187+
exports.resolveNs = function(domain, callback) {
188+
channel.query(domain, dns.NS, callback);
189+
};
143190

144191
var resolveMap = {
145192
'A' : exports.resolve4,

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