net: fix invalid write after end error

Don't error if not ended.
Fixes: #36029
PR-URL: #36043
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: ronag

lib/net.js

@@ -30,6 +30,7 @@ const {
  NumberParseInt,
  ObjectDefineProperty,
  ObjectSetPrototypeOf,
+ ReflectApply,
  Symbol,
 }=primordials;
 
@@ -434,6 +435,11 @@ function afterShutdown() {
 // of the other side sending a FIN. The standard 'write after end'
 // is overly vague, and makes it seem like the user's code is to blame.
 functionwriteAfterFIN(chunk,encoding,cb){
+if(!this.writableEnded){
+returnReflectApply(
+stream.Duplex.prototype.write,this,[chunk,encoding,cb]);
+}
+
 if(typeofencoding==='function'){
 cb=encoding;
 encoding=null;
@@ -947,7 +953,6 @@ Socket.prototype.connect = function(...args) {
 this._unrefTimer();
 
 this.connecting=true;
-this.writable=true;
 
 if(pipe){
 validateString(path,'options.path');

test/parallel/test-net-writable.js

@@ -0,0 +1,15 @@
+'use strict';
+constcommon=require('../common');
+constassert=require('assert');
+constnet=require('net');
+
+constserver=net.createServer(common.mustCall(function(s){
+server.close();
+s.end();
+})).listen(0,'localhost',common.mustCall(function(){
+constsocket=net.connect(this.address().port,'localhost');
+socket.on('end',common.mustCall(()=>{
+assert.strictEqual(socket.writable,true);
+socket.write('hello world');
+}));
+}));

test/parallel/test-socket-write-after-fin-error.js

@@ -26,8 +26,10 @@ const server = net.createServer(function(sock) {
 });
 sock.on('end',function(){
 gotServerEnd=true;
-sock.write(serverData);
-sock.end();
+setImmediate(()=>{
+sock.write(serverData);
+sock.end();
+});
 });
 server.close();
 });