http: keep HTTP/1.1 conns alive even if the Connection header is removed

Previously persistence was completed disabled if you removed this
header, which is not correct for modern HTTP, where the header is
optional and all connections should persist by default regardless.
PR-URL: #46331
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Minwoo Jung <nodecorelab@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ricky Zhou <0x19951125@gmail.com>

Author: pimterry

lib/_http_outgoing.js

@@ -506,8 +506,9 @@ function _storeHeader(firstLine, headers) {
 
 // keep-alive logic
 if(this._removedConnection){
-this._last=true;
-this.shouldKeepAlive=false;
+// shouldKeepAlive is generally true for HTTP/1.1. In that common case,
+// even if the connection header isn't sent, we still persist by default.
+this._last=!this.shouldKeepAlive;
 }elseif(!state.connection){
 constshouldSendKeepAlive=this.shouldKeepAlive&&
 (state.contLen||this.useChunkedEncodingByDefault||this.agent);

test/parallel/test-http-remove-connection-header-persists-connection.js

@@ -0,0 +1,72 @@
+'use strict';
+require('../common');
+constassert=require('assert');
+
+constnet=require('net');
+consthttp=require('http');
+
+constserver=http.createServer(function(request,response){
+// When the connection header is removed, for HTTP/1.1 the connection should still persist.
+// For HTTP/1.0, the connection should be closed after the response automatically.
+response.removeHeader('connection');
+
+response.end('beep boop\n');
+});
+
+constagent=newhttp.Agent({keepAlive: true});
+
+functionmakeHttp11Request(cb){
+http.get({
+port: server.address().port,
+ agent
+},function(res){
+constsocket=res.socket;
+
+assert.strictEqual(res.statusCode,200);
+assert.strictEqual(res.headers.connection,undefined);
+
+res.setEncoding('ascii');
+letresponse='';
+res.on('data',function(chunk){
+response+=chunk;
+});
+res.on('end',function(){
+assert.strictEqual(response,'beep boop\n');
+
+// Wait till next tick to ensure that the socket is returned to the agent before
+// we continue to the next request
+process.nextTick(function(){
+cb(socket);
+});
+});
+});
+}
+
+functionmakeHttp10Request(cb){
+// We have to manually make HTTP/1.0 requests since Node does not allow sending them:
+constsocket=net.connect({port: server.address().port},function(){
+socket.write('GET / HTTP/1.0\r\n'+
+'Host: localhost:'+server.address().port+'\r\n'+
+'\r\n');
+socket.resume();// Ignore the response itself
+
+setTimeout(function(){
+cb(socket);
+},10);
+});
+}
+
+server.listen(0,function(){
+makeHttp11Request(function(firstSocket){
+makeHttp11Request(function(secondSocket){
+// Both HTTP/1.1 requests should have used the same socket:
+assert.strictEqual(firstSocket,secondSocket);
+
+makeHttp10Request(function(socket){
+// The server should have immediately closed the HTTP/1.0 socket:
+assert.strictEqual(socket.closed,true);
+server.close();
+});
+});
+});
+});