http: add setDefaultHeaders option to http.request

This makes it possible to disable the various default headers directly
from the constructor. While this is possible for many use cases by
manually calling removeHeader on the request object instead, when
passing a raw header array to the request constructor the headers are
serialized and prepared to send immediately, and removeHeader cannot
subsequently be used.

With this change, it's now possible to 100% control sent request
headers by passing 'setDefaultHeaders: false' and a raw headers array to
http.request.

PR-URL: #56112
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: pimterry

doc/api/http.md

@@ -3848,8 +3848,13 @@ changes:
   * `port` {number} Port of remote server. **Default:** `defaultPort` if set,
     else `80`.
   * `protocol` {string} Protocol to use. **Default:** `'http:'`.
+  * `setDefaultHeaders` {boolean}: Specifies whether or not to automatically add
+    default headers such as `Connection`, `Content-Length`, `Transfer-Encoding`,
+    and `Host`. If set to `false` then all necessary headers must be added
+    manually. Defaults to `true`.
   * `setHost` {boolean}: Specifies whether or not to automatically add the
-    `Host` header. Defaults to `true`.
+    `Host` header. If provided, this overrides `setDefaultHeaders`. Defaults to
+    `true`.
   * `signal` {AbortSignal}: An AbortSignal that may be used to abort an ongoing
     request.
   * `socketPath` {string} Unix domain socket. Cannot be used if one of `host`

lib/_http_client.js

@@ -199,7 +199,13 @@ function ClientRequest(input, options, cb) {
   const host = optsWithoutSignal.host = validateHost(options.hostname, 'hostname') ||
                                         validateHost(options.host, 'host') || 'localhost';
 
-  const setHost = (options.setHost === undefined || Boolean(options.setHost));
+  const setHost = options.setHost !== undefined ?
+    Boolean(options.setHost) :
+    options.setDefaultHeaders !== false;
+
+  this._removedConnection = options.setDefaultHeaders === false;
+  this._removedContLen = options.setDefaultHeaders === false;
+  this._removedTE = options.setDefaultHeaders === false;
 
   this.socketPath = options.socketPath;
 

test/parallel/test-http-dont-set-default-headers-with-set-header.js

@@ -0,0 +1,33 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(common.mustCall(function(req, res) {
+  assert.deepStrictEqual(req.rawHeaders, [
+    'test', 'value',
+    'HOST', `127.0.0.1:${server.address().port}`,
+    'foo', 'bar',
+    'foo', 'baz',
+    'connection', 'close',
+  ]);
+
+  res.end('ok');
+  server.close();
+}));
+server.listen(0, common.localhostIPv4, function() {
+  const req = http.request({
+    method: 'POST',
+    host: common.localhostIPv4,
+    port: this.address().port,
+    setDefaultHeaders: false,
+  });
+
+  req.setHeader('test', 'value');
+  req.setHeader('HOST', `${common.localhostIPv4}:${server.address().port}`);
+  req.setHeader('foo', ['bar', 'baz']);
+  req.setHeader('connection', 'close');
+
+  req.end();
+});

test/parallel/test-http-dont-set-default-headers-with-setHost.js

@@ -0,0 +1,23 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(common.mustCall(function(req, res) {
+  assert.deepStrictEqual(req.rawHeaders, [
+    'Host', `${common.localhostIPv4}:${server.address().port}`,
+  ]);
+
+  res.end('ok');
+  server.close();
+}));
+server.listen(0, common.localhostIPv4, function() {
+  http.request({
+    method: 'POST',
+    host: common.localhostIPv4,
+    port: this.address().port,
+    setDefaultHeaders: false,
+    setHost: true
+  }).end();
+});

test/parallel/test-http-dont-set-default-headers.js

@@ -0,0 +1,31 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+const server = http.createServer(common.mustCall(function(req, res) {
+  assert.deepStrictEqual(req.rawHeaders, [
+    'host', `${common.localhostIPv4}:${server.address().port}`,
+    'foo', 'bar',
+    'test', 'value',
+    'foo', 'baz',
+  ]);
+
+  res.end('ok');
+  server.close();
+}));
+server.listen(0, common.localhostIPv4, function() {
+  http.request({
+    method: 'POST',
+    host: common.localhostIPv4,
+    port: this.address().port,
+    setDefaultHeaders: false,
+    headers: [
+      'host', `${common.localhostIPv4}:${server.address().port}`,
+      'foo', 'bar',
+      'test', 'value',
+      'foo', 'baz',
+    ]
+  }).end();
+});