http: improve request options.

lib/http/request.js

@@ -49,6 +49,7 @@ function RequestOptions(options) {
   this.maxRedirects = 5;
   this.timeout = 5000;
   this.buffer = false;
+  this.headers = null;
 
   // Hack
   ensureRequires();
@@ -191,6 +192,11 @@ RequestOptions.prototype.fromOptions = function fromOptions(options) {
     assert(typeof options.buffer === 'boolean');
     this.buffer = options.buffer;
   }
+
+  if (options.headers != null) {
+    assert(typeof options.headers === 'object');
+    this.headers = options.headers;
+  }
 };
 
 RequestOptions.prototype.isExpected = function isExpected(type) {
@@ -220,20 +226,21 @@ RequestOptions.prototype.getBackend = function getBackend() {
   return this.ssl ? https : http;
 };
 
-RequestOptions.prototype.toHTTP = function toHTTP() {
-  var query = '';
-  var headers = {};
-  var auth;
+RequestOptions.prototype.getHeaders = function getHeaders() {
+  var headers, auth;
 
-  if (this.query)
-    query = '?' + qs.stringify(this.query);
+  if (this.headers)
+    return this.headers;
+
+  headers = {};
 
   headers['User-Agent'] = this.agent;
 
-  if (this.body) {
+  if (this.type)
     headers['Content-Type'] = getType(this.type);
+
+  if (this.body)
     headers['Content-Length'] = this.body.length + '';
-  }
 
   if (this.auth) {
     auth = this.auth.username + ':' + this.auth.password;
@@ -241,12 +248,21 @@ RequestOptions.prototype.toHTTP = function toHTTP() {
       'Basic ' + new Buffer(auth, 'utf8').toString('base64');
   }
 
+  return headers;
+};
+
+RequestOptions.prototype.toHTTP = function toHTTP() {
+  var query = '';
+
+  if (this.query)
+    query = '?' + qs.stringify(this.query);
+
   return {
     method: this.method,
     host: this.host,
     port: this.port,
     path: this.path + query,
-    headers: headers,
+    headers: this.getHeaders(),
     agent: this.pool ? null : false,
     rejectUnauthorized: this.strictSSL
   };
@@ -561,6 +577,9 @@ function parseType(type) {
     case 'text/html':
     case 'application/xhtml+xml':
       return 'html';
+    case 'text/xml':
+    case 'application/xml':
+      return 'xml';
     case 'text/javascript':
     case 'application/javascript':
       return 'js';
@@ -583,6 +602,8 @@ function getType(type) {
       return 'application/x-www-form-urlencoded; charset=utf-8';
     case 'html':
       return 'text/html; charset=utf-8';
+    case 'xml':
+      return 'application/xml; charset=utf-8';
     case 'js':
       return 'application/javascript; charset=utf-8';
     case 'css':