dgram: add support for UDP connected sockets

Added the `dgram.connect()` and `dgram.disconnect()` methods that
associate/disassociate a udp socket to/from a remote address.
It optimizes for cases where lots of packets are sent to the same
address.
Also added the `dgram.remoteAddress()` method to retrieve the associated
remote address.

PR-URL: https://github.com/nodejs/node/pull/26871
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/test/parallel/test-dgram-connect-send-callback-multi-buffer.js b/test/parallel/test-dgram-connect-send-callback-multi-buffer.js
new file mode 100644
index 0000000000..defc73697c
--- /dev/null
+++ b/test/parallel/test-dgram-connect-send-callback-multi-buffer.js
@@ -0,0 +1,29 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const dgram = require('dgram');
+
+const client = dgram.createSocket('udp4');
+
+const messageSent = common.mustCall((err, bytes) => {
+  assert.strictEqual(bytes, buf1.length + buf2.length);
+});
+
+const buf1 = Buffer.alloc(256, 'x');
+const buf2 = Buffer.alloc(256, 'y');
+
+client.on('listening', common.mustCall(() => {
+  const port = client.address().port;
+  client.connect(port, common.mustCall(() => {
+    client.send([buf1, buf2], messageSent);
+  }));
+}));
+
+client.on('message', common.mustCall((buf, info) => {
+  const expected = Buffer.concat([buf1, buf2]);
+  assert.ok(buf.equals(expected), 'message was received correctly');
+  client.close();
+}));
+
+client.bind(0);