net/http/http_vary_data.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_HTTP_HTTP_VARY_DATA_H_
   6 #define NET_HTTP_HTTP_VARY_DATA_H_
   7
   8 #include "base/md5.h"
   9 #include "net/base/net_export.h"
  10
  11 class Pickle;
  12 class PickleIterator;
  13
  14 namespace net {
  15
  16 struct HttpRequestInfo;
  17 class HttpResponseHeaders;
  18
  19 // Used to implement the HTTP/1.1 Vary header.  This class contains a MD5 hash
  20 // over the request headers indicated by a Vary header.
  21 //
  22 // While RFC 2616 requires strict request header comparisons, it is much
  23 // cheaper to store a MD5 sum, which should be sufficient.  Storing a hash also
  24 // avoids messy privacy issues as some of the request headers could hold
  25 // sensitive data (e.g., cookies).
  26 //
  27 // NOTE: This class does not hold onto the contents of the Vary header.
  28 // Instead, it relies on the consumer to store that and to supply it again to
  29 // the MatchesRequest function for comparing against future HTTP requests.
  30 //
  31 class NET_EXPORT_PRIVATE HttpVaryData {
  32  public:
  33   HttpVaryData();
  34
  35   bool is_valid() const { return is_valid_; }
  36
  37   // Initialize from a request and its corresponding response headers.
  38   //
  39   // Returns true if a Vary header was found in the response headers and that
  40   // Vary header was not empty and did not contain the '*' value.  Upon
  41   // success, the object is also marked as valid such that is_valid() will
  42   // return true.  Otherwise, false is returned to indicate that this object
  43   // is marked as invalid.
  44   //
  45   bool Init(const HttpRequestInfo& request_info,
  46             const HttpResponseHeaders& response_headers);
  47
  48   // Initialize from a pickle that contains data generated by a call to the
  49   // vary data's Persist method.
  50   //
  51   // Upon success, true is returned and the object is marked as valid such that
  52   // is_valid() will return true.  Otherwise, false is returned to indicate
  53   // that this object is marked as invalid.
  54   //
  55   bool InitFromPickle(PickleIterator* pickle_iter);
  56
  57   // Call this method to persist the vary data. Illegal to call this on an
  58   // invalid object.
  59   void Persist(Pickle* pickle) const;
  60
  61   // Call this method to test if the given request matches the previous request
  62   // with which this vary data corresponds.  The |cached_response_headers| must
  63   // be the same response headers used to generate this vary data.
  64   bool MatchesRequest(const HttpRequestInfo& request_info,
  65                       const HttpResponseHeaders& cached_response_headers) const;
  66
  67  private:
  68   // Returns the corresponding request header value.
  69   static std::string GetRequestValue(const HttpRequestInfo& request_info,
  70                                      const std::string& request_header);
  71
  72   // Append to the MD5 context for the given request header.
  73   static void AddField(const HttpRequestInfo& request_info,
  74                        const std::string& request_header,
  75                        base::MD5Context* context);
  76
  77   // A digested version of the request headers corresponding to the Vary header.
  78   base::MD5Digest request_digest_;
  79
  80   // True when request_digest_ contains meaningful data.
  81   bool is_valid_;
  82 };
  83
  84 }  // namespace net
  85
  86 #endif  // NET_HTTP_HTTP_VARY_DATA_H_