Handle the TLS version fallback on the bad_record_mac alert error in

net/http/http_network_transaction.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/http/http_network_transaction.h"
 
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 1201 matching lines @@
 // by the endpoint host, request_->url, rather than considering if they were
 // generated by the SSL proxy. http://crbug.com/69329
 int HttpNetworkTransaction::HandleSSLHandshakeError(int error) {
   DCHECK(request_);
   if (server_ssl_config_.send_client_cert &&
       (error == ERR_SSL_PROTOCOL_ERROR || IsClientCertificateError(error))) {
     session_->ssl_client_auth_cache()->Remove(
         GetHostAndPort(request_->url));
   }
 
+  bool should_fallback = false;
   uint16 version_max = server_ssl_config_.version_max;
 
   switch (error) {
     case ERR_SSL_PROTOCOL_ERROR:
     case ERR_SSL_VERSION_OR_CIPHER_MISMATCH:
       if (version_max >= SSL_PROTOCOL_VERSION_TLS1 &&
           version_max > server_ssl_config_.version_min) {
         // This could be a TLS-intolerant server or a server that chose a
         // cipher suite defined only for higher protocol versions (such as
         // an SSL 3.0 server that chose a TLS-only cipher suite).  Fall
@@ skipping 11 matching lines @@
         // reasons, there is a high risk of breaking the servers if this is
         // done in general.
         // For now SSL 3.0 fallback is disabled for Google servers first,
         // and will be expanded to other servers after enough experiences
         // have been gained showing that this experiment works well with
         // today's Internet.
         if (version_max > SSL_PROTOCOL_VERSION_SSL3 ||
             (server_ssl_config_.unrestricted_ssl3_fallback_enabled ||
              !TransportSecurityState::IsGooglePinnedProperty(
                  request_->url.host(), true /* include SNI */))) {
-          net_log_.AddEvent(
-              NetLog::TYPE_SSL_VERSION_FALLBACK,
-              base::Bind(&NetLogSSLVersionFallbackCallback,
-                         &request_->url, error, server_ssl_config_.version_max,
-                         version_max));
-          server_ssl_config_.version_max = version_max;
-          server_ssl_config_.version_fallback = true;
-          ResetConnectionAndRequestForResend();
-          error = OK;
+          should_fallback = true;
         }
       }
       break;
+    case ERR_SSL_BAD_RECORD_MAC_ALERT:
+      if (version_max >= SSL_PROTOCOL_VERSION_TLS1_1 &&
+          version_max > server_ssl_config_.version_min) {
+        // Some broken SSL devices negotiate TLS 1.0 when sent a TLS 1.1 or
+        // 1.2 ClientHello, but then return a bad_record_mac alert. See
+        // crbug.com/260358. In order to make the fallback as minimal as
+        // possible, this fallback is only triggered for >= TLS 1.1.
+        version_max--;

[wtc, 2013/08/09 21:28:31]

We can also change version_max directly to SSL_PROTOCOL_VERSION_TLS1 here.
That'll require checking
   SSL_PROTOCOL_VERSION_TLS1 >= server_ssl_config_.version_min
instead of
    version_max > server_ssl_config_.version_min
on line 1260.

+        should_fallback = true;
+      }
+      break;
+  }
+
+  if (should_fallback) {
+    net_log_.AddEvent(
+        NetLog::TYPE_SSL_VERSION_FALLBACK,
+        base::Bind(&NetLogSSLVersionFallbackCallback,
+                   &request_->url, error, server_ssl_config_.version_max,
+                   version_max));
+    server_ssl_config_.version_max = version_max;
+    server_ssl_config_.version_fallback = true;
+    ResetConnectionAndRequestForResend();
+    error = OK;
   }
 
   return error;
 }
 
 // This method determines whether it is safe to resend the request after an
 // IO error.  It can only be called in response to request header or body
 // write errors or response header read errors.  It should not be used in
 // other cases, such as a Connect error.
 int HttpNetworkTransaction::HandleIOError(int error) {
@@ skipping 186 matching lines @@
       description = base::StringPrintf("Unknown state 0x%08X (%u)", state,
                                        state);
       break;
   }
   return description;
 }
 
 #undef STATE_CASE
 
 }  // namespace net