Modify data_reduction_proxy_header to support tamper detection logic.

components/data_reduction_proxy/common/data_reduction_proxy_headers.cc

Index: components/data_reduction_proxy/common/data_reduction_proxy_headers.cc
diff --git a/components/data_reduction_proxy/common/data_reduction_proxy_headers.cc b/components/data_reduction_proxy/common/data_reduction_proxy_headers.cc
index 15d35301f390f19d44de969bb7208a787ba03da2..830a5425b6407484ef4968265a07a8f744209800 100644
--- a/components/data_reduction_proxy/common/data_reduction_proxy_headers.cc
+++ b/components/data_reduction_proxy/common/data_reduction_proxy_headers.cc
@@ -18,24 +18,60 @@ using base::StringPiece;
 using base::TimeDelta;
 using net::ProxyService;
 
+namespace {
+const char kChromeProxyHeader[] = "chrome-proxy";
+}  // namespace
+
 namespace data_reduction_proxy {
 
+const char kChromeProxyActionFingerprintChromeProxy[]   = "fcp";
+const char kChromeProxyActionFingerprintVia[]           = "fvia";
+const char kChromeProxyActionFingerprintOtherHeaders[]  = "foh";
+const char kChromeProxyActionFingerprintContentLength[] = "fcl";
+
+bool GetDataReductionProxyActionValue(
+    const net::HttpResponseHeaders* headers,
+    const std::string& action_prefix,
+    std::string* action_value) {
+  DCHECK(!action_prefix.empty());
+  DCHECK(action_prefix[action_prefix.size() - 1] != '=');

[bolian, 2014/07/28 22:59:18]

I don't think you need this DCHECK. Unnecessary restriction.

[xingx1, 2014/07/29 00:47:40]

Done.

[bolian, 2014/07/29 01:36:20]

I don't see this and other comments are addressed.
Assume you changed locally and forgot to upload?

+  void* iter = NULL;
+  std::string value;
+  std::string prefix = action_prefix + "=";
+
+  while (headers->EnumerateHeader(&iter, kChromeProxyHeader, &value)) {
+    // ">=" to allow empty action value.
+    if (value.size() >= prefix.size()) {
+      if (LowerCaseEqualsASCII(value.begin(),
+                               value.begin() + prefix.size(),
+                               prefix.c_str())) {
+        if (action_value)
+          *action_value = value.substr(prefix.size());
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
 bool GetDataReductionProxyBypassDuration(
     const net::HttpResponseHeaders* headers,
     const std::string& action_prefix,
     base::TimeDelta* duration) {
+  DCHECK(!action_prefix.empty());
+  DCHECK(action_prefix[action_prefix.size() - 1] != '=');
   void* iter = NULL;
   std::string value;
-  std::string name = "chrome-proxy";
+  std::string prefix = action_prefix + "=";
 
-  while (headers->EnumerateHeader(&iter, name, &value)) {
-    if (value.size() > action_prefix.size()) {
+  while (headers->EnumerateHeader(&iter, kChromeProxyHeader, &value)) {
+    if (value.size() > prefix.size()) {
       if (LowerCaseEqualsASCII(value.begin(),
-                               value.begin() + action_prefix.size(),
-                               action_prefix.c_str())) {
+                               value.begin() + prefix.size(),
+                               prefix.c_str())) {
         int64 seconds;
         if (!base::StringToInt64(
-                StringPiece(value.begin() + action_prefix.size(), value.end()),
+                StringPiece(value.begin() + prefix.size(), value.end()),
                 &seconds) || seconds < 0) {
           continue;  // In case there is a well formed instruction.
         }
@@ -63,20 +99,21 @@ bool GetDataReductionProxyInfo(const net::HttpResponseHeaders* headers,
   // 'block' takes precedence over 'bypass', so look for it first.
   // TODO(bengr): Reduce checks for 'block' and 'bypass' to a single loop.
   if (GetDataReductionProxyBypassDuration(
-      headers, "block=", &proxy_info->bypass_duration)) {
+      headers, "block", &proxy_info->bypass_duration)) {
     proxy_info->bypass_all = true;
     return true;
   }
 
   // Next, look for 'bypass'.
   if (GetDataReductionProxyBypassDuration(
-      headers, "bypass=", &proxy_info->bypass_duration)) {
+      headers, "bypass", &proxy_info->bypass_duration)) {
     return true;
   }
   return false;
 }
 
-bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers) {
+bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers,
+                                    bool* has_intermediary) {
   const size_t kVersionSize = 4;
   const char kDataReductionProxyViaValue[] = "Chrome-Compression-Proxy";
   size_t value_len = strlen(kDataReductionProxyViaValue);
@@ -88,8 +125,11 @@ bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers) {
   // 'Via: 1.1 Chrome-Compression-Proxy'
   while (headers->EnumerateHeader(&iter, "via", &value)) {
     if (value.size() >= kVersionSize + value_len &&
-        !value.compare(kVersionSize, value_len, kDataReductionProxyViaValue))
+        !value.compare(kVersionSize, value_len, kDataReductionProxyViaValue)) {
+      if (has_intermediary)
+        *has_intermediary = !(headers->EnumerateHeader(&iter, "via", &value));

[bolian, 2014/07/28 22:59:18]

Are you sure it is ok to call EnumerateHeader inside EnumerateHeader loop?

[xingx1, 2014/07/29 00:47:40]

Yes, it should be fine, |iter| will be updated.

       return true;
+    }
   }
 
   // TODO(bengr): Remove deprecated header value.
@@ -97,8 +137,11 @@ bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers) {
       "1.1 Chrome Compression Proxy";
   iter = NULL;
   while (headers->EnumerateHeader(&iter, "via", &value))
-    if (value == kDeprecatedDataReductionProxyViaValue)
+    if (value == kDeprecatedDataReductionProxyViaValue) {
+      if (has_intermediary)
+        *has_intermediary = !(headers->EnumerateHeader(&iter, "via", &value));
       return true;
+    }
 
   return false;
 }
@@ -136,7 +179,7 @@ GetDataReductionProxyBypassType(
       !headers->HasHeader("Proxy-Authenticate")) {
     return ProxyService::MALFORMED_407;
   }
-  if (!HasDataReductionProxyViaHeader(headers) &&
+  if (!HasDataReductionProxyViaHeader(headers, NULL) &&
       (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