http: cleanup ClientRequest oncreate

PR-URL: #36862
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Daniele Belardi <dwon.dnl@gmail.com>

lib/_http_client.js

@@ -44,6 +44,7 @@ const {
 const net = require('net');
 const url = require('url');
 const assert = require('internal/assert');
+const { once } = require('internal/util');
 const {
   _checkIsHttpToken: checkIsHttpToken,
   debug,
@@ -240,8 +241,6 @@ function ClientRequest(input, options, cb) {
   this.host = host;
   this.protocol = protocol;
 
-  let called = false;
-
   if (this.agent) {
     // If there is an agent we should default to Connection:keep-alive,
     // but only if the Agent will actually reuse the connection!
@@ -305,18 +304,6 @@ function ClientRequest(input, options, cb) {
                       options.headers);
   }
 
-  const oncreate = (err, socket) => {
-    if (called)
-      return;
-    called = true;
-    if (err) {
-      process.nextTick(() => this.emit('error', err));
-      return;
-    }
-    this.onSocket(socket);
-    this._deferToConnect(null, null, () => this._flush());
-  };
-
   // initiate connection
   if (this.agent) {
     this.agent.addRequest(this, options);
@@ -325,20 +312,27 @@ function ClientRequest(input, options, cb) {
     this._last = true;
     this.shouldKeepAlive = false;
     if (typeof options.createConnection === 'function') {
-      const newSocket = options.createConnection(options, oncreate);
-      if (newSocket && !called) {
-        called = true;
-        this.onSocket(newSocket);
-      } else {
-        return;
+      const oncreate = once((err, socket) => {
+        if (err) {
+          process.nextTick(() => this.emit('error', err));
+        } else {
+          this.onSocket(socket);
+        }
+      });
+
+      try {
+        const newSocket = options.createConnection(options, oncreate);
+        if (newSocket) {
+          oncreate(null, newSocket);
+        }
+      } catch (err) {
+        oncreate(err);
       }
     } else {
       debug('CLIENT use net.createConnection', options);
       this.onSocket(net.createConnection(options));
     }
   }
-
-  this._deferToConnect(null, null, () => this._flush());
 }
 ObjectSetPrototypeOf(ClientRequest.prototype, OutgoingMessage.prototype);
 ObjectSetPrototypeOf(ClientRequest, OutgoingMessage);
@@ -843,6 +837,7 @@ function onSocketNT(req, socket, err) {
     _destroy(req, null, err);
   } else {
     tickOnSocket(req, socket);
+    req._flush();
   }
 }