net: check EADDRINUSE after binding localPort

PR-URL: https://github.com/nodejs/node/pull/15097
Fixes: https://github.com/nodejs/node/issues/15084
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/test/parallel/test-net-client-bind-twice.js b/test/parallel/test-net-client-bind-twice.js
new file mode 100644
index 0000000000..ca7eb502d8
--- /dev/null
+++ b/test/parallel/test-net-client-bind-twice.js
@@ -0,0 +1,26 @@
+'use strict';
+
+// This tests that net.connect() from a used local port throws EADDRINUSE.
+
+const common = require('../common');
+const assert = require('assert');
+const net = require('net');
+
+const server1 = net.createServer(common.mustNotCall());
+server1.listen(0, common.localhostIPv4, common.mustCall(() => {
+  const server2 = net.createServer(common.mustNotCall());
+  server2.listen(0, common.localhostIPv4, common.mustCall(() => {
+    const client = net.connect({
+      host: common.localhostIPv4,
+      port: server1.address().port,
+      localAddress: common.localhostIPv4,
+      localPort: server2.address().port
+    }, common.mustNotCall());
+
+    client.on('error', common.mustCall((err) => {
+      assert.strictEqual(err.code, 'EADDRINUSE');
+      server1.close();
+      server2.close();
+    }));
+  }));
+}));