Modify data_reduction_proxy_header to support tamper detection logic.

components/data_reduction_proxy/common/data_reduction_proxy_headers.h

 // 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.
 
 #ifndef COMPONENTS_DATA_REDUCTION_PROXY_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_
 #define COMPONENTS_DATA_REDUCTION_PROXY_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_
 
 #include <string>
 
 #include "base/macros.h"
@@ skipping 19 matching lines @@
 // delay. Sets |proxy_info->bypass_duration| to the specified delay if greater
 // than 0, and to 0 otherwise to indicate that the default proxy delay
 // (as specified in |ProxyList::UpdateRetryInfoOnFallback|) should be used.
 // If all available data reduction proxies should by bypassed, |bypass_all| is
 // set to true. |proxy_info| must be non-NULL.
 bool GetDataReductionProxyInfo(
     const net::HttpResponseHeaders* headers,
     DataReductionProxyInfo* proxy_info);
 
 // Returns true if the response contain the data reduction proxy Via header
-// value. Used to check the integrity of data reduction proxy responses.
-bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers);
+// value. If data reduction proxy Via header value exists, set |is_the_last|

[bengr, 2014/07/16 19:23:56]

I can't parse this comment. How about:

// Returns true if the response contains the data reduction proxy Via header 
// value. If non-NULL, sets |has_intermediary| to true if another server added a

// Via header after the data reduction proxy, and to false otherwise.

Also, change is_the_last to has_intermediary

[xingx, 2014/07/16 21:22:33]

Done.

+// as whether it occurs at the last if |is_the_last| is not NULL. Used to check
+// the integrity of data reduction proxy responses and whether there are other
+// middleboxes between data reduction proxy and chrome.
+bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers,
+                                    bool* is_the_last);
 
 // Returns the reason why the Chrome proxy should be bypassed or not, and
 // populates |proxy_info| with information on how long to bypass if
 // applicable.
 net::ProxyService::DataReductionProxyBypassEventType
 GetDataReductionProxyBypassEventType(
     const net::HttpResponseHeaders* headers,
     DataReductionProxyInfo* proxy_info);
 
+// Searches for the specified Chrome-Proxy action, and if present saves its
+// value as a string in |action_value|. Only keeps the first one and ignores
+// the rest if multiple actions match |action_prefix|.
+bool GetDataReductionProxyActionValue(
+    const net::HttpResponseHeaders* headers,
+    const std::string& action_prefix,
+    std::string* action_value);
+
 // Searches for the specified Chrome-Proxy action, and if present interprets
 // its value as a duration in seconds.
 bool GetDataReductionProxyBypassDuration(
     const net::HttpResponseHeaders* headers,
     const std::string& action_prefix,
     base::TimeDelta* duration);
 
 }  // namespace data_reduction_proxy
 #endif  // COMPONENTS_DATA_REDUCTION_PROXY_COMMON_DATA_REDUCTION_PROXY_HEADERS_H_