Bypass data reduction proxy if no handler is found for a 407 error.

components/data_reduction_proxy/common/data_reduction_proxy_headers.cc

 // Copyright 2014 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 "components/data_reduction_proxy/common/data_reduction_proxy_headers.h"
 
 #include <string>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
@@ skipping 103 matching lines @@
     if (data_reduction_proxy_info->bypass_duration < TimeDelta::FromMinutes(30))
       return ProxyService::SHORT_BYPASS;
     return ProxyService::LONG_BYPASS;
   }
   if (headers->response_code() == net::HTTP_INTERNAL_SERVER_ERROR ||
       headers->response_code() == net::HTTP_BAD_GATEWAY ||
       headers->response_code() == net::HTTP_SERVICE_UNAVAILABLE) {
     // Fall back if a 500, 502 or 503 is returned.
     return ProxyService::INTERNAL_SERVER_ERROR_BYPASS;
   }
+  // TODO(kundaji): Bypass if Proxy-Authenticate header value cannot be
+  // interpreted by data reduction proxy.
+  if (headers->response_code() == net::HTTP_PROXY_AUTHENTICATION_REQUIRED &&
+      !headers->HasHeader("Proxy-Authenticate")) {
+    return ProxyService::MALFORMED_407_BYPASS;
+  }
   if (!IsDataReductionProxyResponse(headers) &&
       (headers->response_code() != net::HTTP_NOT_MODIFIED)) {
     // A Via header might not be present in a 304. Since the goal of a 304
     // response is to minimize information transfer, a sender in general
     // should not generate representation metadata other than Cache-Control,
     // Content-Location, Date, ETag, Expires, and Vary.
 
     // The proxy Via header might also not be present in a 4xx response.
     // Separate this case from other responses that are missing the header.
     if (headers->response_code() >= net::HTTP_BAD_REQUEST &&
         headers->response_code() < net::HTTP_INTERNAL_SERVER_ERROR) {
       return ProxyService::PROXY_4XX_BYPASS;
     }
     return ProxyService::MISSING_VIA_HEADER;
   }
   // There is no bypass event.
   return ProxyService::BYPASS_EVENT_TYPE_MAX;
 }
 
 }  // namespace data_reduction_proxy