Rewrite HTTP requests over port 443 to HTTPS (in the HSTS code).

net/url_request/url_request.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/url_request/url_request.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
@@ skipping 1009 matching lines @@
                       NetLog::IntegerCallback("priority", priority_));
     job_->SetPriority(priority_);
   }
 }
 
 bool URLRequest::GetHSTSRedirect(GURL* redirect_url) const {
   const GURL& url = this->url();
   if (!url.SchemeIs("http"))
     return false;
   TransportSecurityState* state = context()->transport_security_state();
-  if (state && state->ShouldUpgradeToSSL(url.host())) {
+  bool shouldUpgradeDueToHost = state && state->ShouldUpgradeToSSL(url.host());
+  // If the port is 443, always redirect. This prevents sites from using AJAX
+  // calls to tell if HSTS is set for a domain (by visiting
+  // http://example.com:443), which is a privacy leak if the site is not on the
+  // preload list.
+  // https://code.google.com/p/chromium/issues/detail?id=436451
+  bool shouldUpgradeDueToPort = url.has_port() && url.IntPort() == 443;
+  if (shouldUpgradeDueToHost || shouldUpgradeDueToPort) {
     url::Replacements<char> replacements;
     const char kNewScheme[] = "https";
     replacements.SetScheme(kNewScheme, url::Component(0, strlen(kNewScheme)));
     *redirect_url = url.ReplaceComponents(replacements);
     return true;
   }
   return false;
 }
 
 void URLRequest::NotifyAuthRequired(AuthChallengeInfo* auth_info) {
@@ skipping 184 matching lines @@
       new base::debug::StackTrace(NULL, 0);
   *stack_trace_copy = stack_trace;
   stack_trace_.reset(stack_trace_copy);
 }
 
 const base::debug::StackTrace* URLRequest::stack_trace() const {
   return stack_trace_.get();
 }
 
 }  // namespace net