dgram: copy the list in send

This commit fix a possible crash situation in dgram send().
A crash is possible if an array is passed, and then altered after the
send call, as the call to libuv is wrapped in process.nextTick().
It also avoid sending an empty array to libuv by allocating an empty
buffer. It also does some cleanup inside send() to increase readability.

It removes test flakyness by use common.mustCall and
common.platformTimeout. Fixes situations were some events were not
asserted to be emitted.

Fixes: https://github.com/nodejs/node/issues/6616
PR-URL: https://github.com/nodejs/node/pull/6804
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

1 files changed, 33 insertions, 0 deletions

diff --git a/test/parallel/test-dgram-send-multi-buffer-copy.js b/test/parallel/test-dgram-send-multi-buffer-copy.js
new file mode 100644
index 0000000000..6ece56e02a
--- /dev/null
+++ b/test/parallel/test-dgram-send-multi-buffer-copy.js
@@ -0,0 +1,33 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const dgram = require('dgram');
+
+const client = dgram.createSocket('udp4');
+
+const timer = setTimeout(function() {
+  throw new Error('Timeout');
+}, common.platformTimeout(200));
+
+const onMessage = common.mustCall(function(err, bytes) {
+  assert.equal(bytes, buf1.length + buf2.length);
+  clearTimeout(timer);
+});
+
+const buf1 = Buffer.alloc(256, 'x');
+const buf2 = Buffer.alloc(256, 'y');
+
+client.on('listening', function() {
+  const toSend = [buf1, buf2];
+  client.send(toSend, common.PORT, common.localhostIPv4, onMessage);
+  toSend.splice(0, 2);
+});
+
+client.on('message', common.mustCall(function onMessage(buf, info) {
+  const expected = Buffer.concat([buf1, buf2]);
+  assert.ok(buf.equals(expected), 'message was received correctly');
+  client.close();
+}));
+
+client.bind(common.PORT);