net: don't prefer IPv4 addresses during resolution

Currently the address resolution family defaults to IPv4. Instead remove
the preference and instead resolve to a family suitable for the host.

Expose the getaddrinfo flags and allow them to be passed.

Add documentation about new flags.

Reviewed-by: Trevor Norris <trev.norris@gmail.com>

2 files changed, 113 insertions, 9 deletions

diff --git a/test/internet/test-dns.js b/test/internet/test-dns.js
index 6165b30a3a..902545c175 100644
--- a/test/internet/test-dns.js
+++ b/test/internet/test-dns.js
@@ -337,6 +337,36 @@ TEST(function test_lookup_ipv4_implicit(done) {
 });
 
 
+TEST(function test_lookup_ipv4_explicit_object(done) {
+  var req = dns.lookup('www.google.com', {
+    family: 4
+  }, function(err, ip, family) {
+    if (err) throw err;
+    assert.ok(net.isIPv4(ip));
+    assert.strictEqual(family, 4);
+
+    done();
+  });
+
+  checkWrap(req);
+});
+
+
+TEST(function test_lookup_ipv4_hint_addrconfig(done) {
+  var req = dns.lookup('www.google.com', {
+    hint: dns.ADDRCONFIG
+  }, function(err, ip, family) {
+    if (err) throw err;
+    assert.ok(net.isIPv4(ip));
+    assert.strictEqual(family, 4);
+
+    done();
+  });
+
+  checkWrap(req);
+});
+
+
 TEST(function test_lookup_ipv6_explicit(done) {
   var req = dns.lookup('ipv6.google.com', 6, function(err, ip, family) {
     if (err) throw err;
@@ -365,6 +395,36 @@ TEST(function test_lookup_ipv6_implicit(done) {
 */
 
 
+TEST(function test_lookup_ipv6_explicit_object(done) {
+  var req = dns.lookup('ipv6.google.com', {
+    family: 6
+  }, function(err, ip, family) {
+    if (err) throw err;
+    assert.ok(net.isIPv6(ip));
+    assert.strictEqual(family, 6);
+
+    done();
+  });
+
+  checkWrap(req);
+});
+
+
+TEST(function test_lookup_ipv6_hint(done) {
+  var req = dns.lookup('ipv6.google.com', {
+    hint: dns.V4MAPPED
+  }, function(err, ip, family) {
+    if (err) throw err;
+    assert.ok(net.isIPv6(ip));
+    assert.strictEqual(family, 6);
+
+    done();
+  });
+
+  checkWrap(req);
+});
+
+
 TEST(function test_lookup_failure(done) {
   var req = dns.lookup('does.not.exist', 4, function(err, ip, family) {
     assert.ok(err instanceof Error);
diff --git a/test/simple/test-dns.js b/test/simple/test-dns.js
index e7dce4b2ee..48f7d5f40a 100644
--- a/test/simple/test-dns.js
+++ b/test/simple/test-dns.js
@@ -27,6 +27,8 @@ var dns = require('dns');
 var existing = dns.getServers();
 assert(existing.length);
 
+function noop() {}
+
 var goog = [
   '8.8.8.8',
   '8.8.4.4',
@@ -61,12 +63,54 @@ assert.deepEqual(dns.getServers(), portsExpected);
 assert.doesNotThrow(function () { dns.setServers([]); });
 assert.deepEqual(dns.getServers(), []);
 
-assert.throws(
-  function() {
-    dns.resolve('test.com', [], new Function);
-  },
-  function(err) {
-    return !(err instanceof TypeError);
-  },
-  "Unexpected error"
-);
+assert.throws(function() {
+  dns.resolve('test.com', [], noop);
+}, function(err) {
+  return !(err instanceof TypeError);
+}, 'Unexpected error');
+
+assert.throws(function() {
+  dns.lookup('www.google.com', { hints: 1 }, noop);
+});
+
+assert.throws(function() {
+  dns.lookup('www.google.com');
+}, 'invalid arguments: callback must be passed');
+
+assert.throws(function() {
+  dns.lookup('www.google.com', 4);
+}, 'invalid arguments: callback must be passed');
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', 6, noop);
+});
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', {}, noop);
+});
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', {
+    family: 4,
+    hints: 0
+  }, noop);
+});
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', {
+    family: 6,
+    hints: dns.ADDRCONFIG
+  }, noop);
+});
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', {
+    hints: dns.V4MAPPED
+  }, noop);
+});
+
+assert.doesNotThrow(function() {
+  dns.lookup('www.google.com', {
+    hints: dns.ADDRCONFIG | dns.V4MAPPED
+  }, noop);
+});