net: fix socket._getpeername

Fixes: #43009

If calling `this._handle.getpeername` returns an error at the first
call, its result shouldn't be cached to `this._peername`.

Signed-off-by: Daeyeon Jeong daeyeon.dev@gmail.com

PR-URL: #43010
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Zeyu "Alex" Yang <himself65@outlook.com>

lib/net.js

@@ -785,9 +785,10 @@ Socket.prototype._getpeername = function() {
   if (!this._handle || !this._handle.getpeername || this.connecting) {
     return this._peername || {};
   } else if (!this._peername) {
-    this._peername = {};
-    // FIXME(bnoordhuis) Throw when the return value is not 0?
-    this._handle.getpeername(this._peername);
+    const out = {};
+    const err = this._handle.getpeername(out);
+    if (err) return out;
+    this._peername = out;
   }
   return this._peername;
 };

test/parallel/test-net-remote-address.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const common = require('../common');
+const net = require('net');
+const { strictEqual } = require('assert');
+
+const server = net.createServer();
+
+server.listen(common.mustCall(function() {
+  const socket = net.connect({ port: server.address().port });
+
+  strictEqual(socket.connecting, true);
+  strictEqual(socket.remoteAddress, undefined);
+
+  socket.on('connect', common.mustCall(function() {
+    strictEqual(socket.remoteAddress !== undefined, true);
+    socket.end();
+  }));
+
+  socket.on('end', common.mustCall(function() {
+    server.close();
+  }));
+}));