From f9f841810840716fa01b1e3cd890f58dbc362f7b Mon Sep 17 00:00:00 2001
From: Matteo Collina <hello@matteocollina.com>
Date: Tue, 26 May 2015 09:17:00 +0200
Subject: [PATCH] dgram: do not emit error for failed DNS lookups in send()

Modifies the dgram send() method to not emit errors when a DNS lookup
fails if there is no callback. Given that the same UDP socket can be
used to send messages to different hosts, the socket can be reused even
if one of those send() fails.

This slightly changes the behavior of a stable API, so that it behaves
as users would expect to.

This is based of @chrisdickinson https://github.com/joyent/node/pull/7738.
Discussion in https://github.com/joyent/node/issues/4846.
---
 lib/dgram.js                                  |  6 +--
 .../test-dgram-send-cb-quelches-error.js      | 37 +++++++++++++
 .../test-dgram-send-cb-quelches-error.js      | 54 -------------------
 3 files changed, 38 insertions(+), 59 deletions(-)
 create mode 100644 test/internet/test-dgram-send-cb-quelches-error.js
 delete mode 100644 test/simple/test-dgram-send-cb-quelches-error.js

diff --git a/lib/dgram.js b/lib/dgram.js
index c3a2c004b86867..681de91d4e04b9 100644
--- a/lib/dgram.js
+++ b/lib/dgram.js
@@ -299,12 +299,8 @@ Socket.prototype.send = function(buffer,
 
   self._handle.lookup(address, function(ex, ip) {
     if (ex) {
-      if (callback) {
+      if (typeof callback === 'function') {
         callback(ex);
-
-        if (self.listeners('error').length)
-          self.emit('error', ex);
-
         return;
       }
 
diff --git a/test/internet/test-dgram-send-cb-quelches-error.js b/test/internet/test-dgram-send-cb-quelches-error.js
new file mode 100644
index 00000000000000..e89306b2c29aa2
--- /dev/null
+++ b/test/internet/test-dgram-send-cb-quelches-error.js
@@ -0,0 +1,37 @@
+'use strict';
+var common = require('../common');
+var mustCall = common.mustCall;
+var assert = require('assert');
+var dgram = require('dgram');
+var dns = require('dns');
+
+var socket = dgram.createSocket('udp4');
+var buffer = new Buffer('gary busey');
+
+dns.setServers([]);
+
+socket.once('error', onEvent);
+
+// assert that:
+// * callbacks act as "error" listeners if given.
+// * error is never emitter for missing dns entries
+//   if a callback that handles error is present
+// * error is emitted if a callback with no argument is passed
+socket.send(buffer, 0, buffer.length, 100,
+            'dne.example.com', mustCall(callbackOnly));
+
+function callbackOnly(err) {
+  assert.ok(err);
+  socket.removeListener('error', onEvent);
+  socket.on('error', mustCall(onError));
+  socket.send(buffer, 0, buffer.length, 100, 'dne.example.com');
+}
+
+function onEvent(err) {
+  assert.fail('Error should not be emitted if there is callback');
+}
+
+function onError(err) {
+  assert.ok(err);
+  socket.close();
+}
diff --git a/test/simple/test-dgram-send-cb-quelches-error.js b/test/simple/test-dgram-send-cb-quelches-error.js
deleted file mode 100644
index d5f29f9dafa39f..00000000000000
--- a/test/simple/test-dgram-send-cb-quelches-error.js
+++ /dev/null
@@ -1,54 +0,0 @@
-// Copyright Joyent, Inc. and other Node contributors.
-//
-// Permission is hereby granted, free of charge, to any person obtaining a
-// copy of this software and associated documentation files (the
-// "Software"), to deal in the Software without restriction, including
-// without limitation the rights to use, copy, modify, merge, publish,
-// distribute, sublicense, and/or sell copies of the Software, and to permit
-// persons to whom the Software is furnished to do so, subject to the
-// following conditions:
-//
-// The above copyright notice and this permission notice shall be included
-// in all copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
-// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
-// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
-// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
-// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
-// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
-// USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-var common = require('../common');
-var assert = require('assert');
-var dgram = require('dgram');
-var dns = require('dns');
-
-var socket = dgram.createSocket('udp4');
-var buffer = new Buffer('gary busey');
-var times = 0;
-
-dns.setServers([]);
-
-// assert that:
-// * callbacks act as "error" listeners if given.
-// * callbacks and error events are emitted in a certain order.
-socket.send(buffer, 0, buffer.length, 100, 'dne.example.com', callbackOnly);
-
-function callbackOnly(err) {
-  assert.ok(err);
-  socket.once('error', onEvent);
-  socket.send(buffer, 0, buffer.length, 100, 'dne.example.com', onCallback);
-}
-
-function onEvent(err) {
-  assert.ok(err);
-  assert.equal(times, 0); 
-  times++;
-}
-
-function onCallback(err) {
-  assert.ok(err);
-  assert.equal(times, 1); 
-  socket.close();
-}