How to use dns - 10 common examples
To help you get started, we’ve selected a few dns examples, based on popular ways it is used in public projects.
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apigee / trireme / node12 / node12src / src / main / javascript / io / apigee / trireme / node12 / node / net.js View on Github 
dnsopts.hints = dns.ADDRCONFIG;
// The AI_V4MAPPED hint is not supported on FreeBSD, and getaddrinfo
// returns EAI_BADFLAGS. However, it seems to be supported on most other
// systems. See
// http://lists.freebsd.org/pipermail/freebsd-bugs/2008-February/028260.html
// and
// https://svnweb.freebsd.org/base/head/lib/libc/net/getaddrinfo.c?r1=172052&r2=175955
// for more information on the lack of support for FreeBSD.
if (process.platform !== 'freebsd')
dnsopts.hints |= dns.V4MAPPED;
}
debug('connect: find host ' + host);
debug('connect: dns options ' + dnsopts);
self._host = host;
dns.lookup(host, dnsopts, function(err, ip, addressType) {
self.emit('lookup', err, ip, addressType);
// It's possible we were destroyed while looking this up.
// XXX it would be great if we could cancel the promise returned by
// the look up.
if (!self._connecting) return;
if (err) {
// net.createConnection() creates a net.Socket object and
// immediately calls net.Socket.connect() on it (that's us).
// There are no event listeners registered yet so defer the
// error event to the next tick.
process.nextTick(function() {
self.emit('error', err);
self._destroy();
});dnsopts.hints = dns.ADDRCONFIG;
// The AI_V4MAPPED hint is not supported on FreeBSD, and getaddrinfo
// returns EAI_BADFLAGS. However, it seems to be supported on most other
// systems. See
// http://lists.freebsd.org/pipermail/freebsd-bugs/2008-February/028260.html
// and
// https://svnweb.freebsd.org/base/head/lib/libc/net/getaddrinfo.c?r1=172052&r2=175955
// for more information on the lack of support for FreeBSD.
if (process.platform !== 'freebsd')
dnsopts.hints |= dns.V4MAPPED;
}
debug('connect: find host ' + host);
debug('connect: dns options ' + dnsopts);
self._host = host;
dns.lookup(host, dnsopts, function(err, ip, addressType) {
self.emit('lookup', err, ip, addressType);
// It's possible we were destroyed while looking this up.
// XXX it would be great if we could cancel the promise returned by
// the look up.
if (!self._connecting) return;
if (err) {
// net.createConnection() creates a net.Socket object and
// immediately calls net.Socket.connect() on it (that's us).
// There are no event listeners registered yet so defer the
// error event to the next tick.
process.nextTick(function() {
self.emit('error', err);
self._destroy();
});// been solved before in https://github.com/nodejs/node/pull/12342, but was
// reverted as it had unintended side effects.
if (Array.isArray(args[0]) && args[0][normalizedArgsSymbol])
normalized = args[0];
else
normalized = normalizeArgs(args);
let options = normalized[0];
let cb = normalized[1];
if (!options.host)
options.host = '127.0.0.1';
let family = options.port === undefined ? 0 : native.isIP(options.host);
if (options.port === undefined || family)
this._connect(options, family, options.port === undefined ? options.path : options.host, cb);
else
dns.lookup(options.host, (err, host, family) => {
this.emit('lookup', err, options.host, family, host);
if (err) {
this.connecting = false;
this._updateRef();
this.emit('error', err);
return;
}
if (this.destroyed) {
this.connecting = false;
this._updateRef();
return;
}
this._connect(options, family, host, cb);
});var lookup = function(address, family, callback) {
// implicit 'bind before send' needs to run on the same tick
var matchedFamily = isIP(address);
if (matchedFamily)
return callback(null, address, matchedFamily);
if (!dns)
dns = require('dns');
return dns.lookup(address, family, callback);
};function resolve4(next) {
dns.resolve4(name, function resolve4Callback(err, arr) {
if (arr) {
arr.forEach(address => addresses.push({ address, isIPv6: false }));
}
// Ignore error
next();
});
},
function resolve6(next) {TEST(function test_lookup_ipv4_explicit(done) {
var req = dns.lookup('www.google.com', 4, function(err, ip, family) {
if (err) throw err;
assert.ok(net.isIPv4(ip));
assert.strictEqual(family, 4);
done();
});
checkWrap(req);
});return function(errr, stdout) {
var expected = stdout.substr(0, stdout.length - 1).split('\n');
var reversing = dns.reverse(myIp, function(error, domains, ttl, cname) {
if (error) domains = [];
cmpResults(expected, domains, ttl, cname);
});
}
}TEST(function test_lookup_localhost_ipv4(done) {
var req = dns.lookup('localhost', 4, function(err, ip, family) {
if (err) throw err;
assert.strictEqual(ip, '127.0.0.1');
assert.strictEqual(family, 4);
done();
});
checkWrap(req);
});resolution.addCallback(function (addresses, ttl, cname) {
puts("addresses: " + JSON.stringify(addresses));
puts("ttl: " + JSON.stringify(ttl));
puts("cname: " + JSON.stringify(cname));
for (var i = 0; i < addresses.length; i++) {
var a = addresses[i];
var reversing = dns.reverse(a);
reversing.addCallback( function (domains, ttl, cname) {
puts("reverse for " + a + ": " + JSON.stringify(domains));
});
reversing.addErrback( function (code, msg) {
puts("reverse for " + a + " failed: " + msg);
});
}
});TEST(function test_resolve4(done) {
var req = dns.resolve4('www.google.com', function(err, ips) {
if (err) throw err;
assert.ok(ips.length > 0);
for (var i = 0; i < ips.length; i++) {
assert.ok(isIPv4(ips[i]));
}
done();
});
checkWrap(req);
});
