Suppress pause-and-buffer behavior when the HTTP response won't satisfy future requests via cache.

net/http/http_util.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.
 
 // The rules for parsing content-types were borrowed from Firefox:
 // http://lxr.mozilla.org/mozilla/source/netwerk/base/src/nsURLHelper.cpp#834
 
 #include "net/http/http_util.h"
 
 #include <algorithm>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/stringprintf.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "base/string_util.h"
+#include "base/time.h"
 
 using std::string;
 
 namespace net {
 
 //-----------------------------------------------------------------------------
 
 // Return the index of the closing quote of the string, if any.
 static size_t FindStringEnd(const string& line, size_t start, char delim) {
   DCHECK(start < line.length() && line[start] == delim &&
@@ skipping 664 matching lines @@
 void HttpUtil::AppendHeaderIfMissing(const char* header_name,
                                      const std::string& header_value,
                                      std::string* headers) {
   if (header_value.empty())
     return;
   if (net::HttpUtil::HasHeader(*headers, header_name))
     return;
   *headers += std::string(header_name) + ": " + header_value + "\r\n";
 }
 
+bool HttpUtil::HasStrongValidators(HttpVersion version,
+                                   const std::string& etag_header,
+                                   const std::string& last_modified_header,
+                                   const std::string& date_header) {
+  if (version < HttpVersion(1, 1))
+    return false;
+
+  if (!etag_header.empty()) {
+    size_t slash = etag_header.find('/');
+    if (slash == std::string::npos || slash == 0)
+      return true;
+
+    std::string::const_iterator i = etag_header.begin();
+    std::string::const_iterator j = etag_header.begin() + slash;
+    TrimLWS(&i, &j);
+    if (!LowerCaseEqualsASCII(i, j, "w"))
+      return true;
+  }
+
+  base::Time last_modified;
+  if (!base::Time::FromString(last_modified_header.c_str(), &last_modified))
+    return false;
+
+  base::Time date;
+  if (!base::Time::FromString(date_header.c_str(), &date))
+    return false;
+
+  return ((date - last_modified).InSeconds() >= 60);
+}
+
 // BNF from section 4.2 of RFC 2616:
 //
 //   message-header = field-name ":" [ field-value ]
 //   field-name     = token
 //   field-value    = *( field-content | LWS )
 //   field-content  = <the OCTETs making up the field-value
 //                     and consisting of either *TEXT or combinations
 //                     of token, separators, and quoted-string>
 //
 
@@ skipping 146 matching lines @@
       value_is_quoted_ = true;
       // Do not store iterators into this. See declaration of unquoted_value_.
       unquoted_value_ = HttpUtil::Unquote(value_begin_, value_end_);
     }
   }
 
   return true;
 }
 
 }  // namespace net