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
11class Pickle;
12class PickleIterator;
13
14namespace net {
15
16struct HttpRequestInfo;
17class 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//
31class 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(const Pickle& pickle, 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_
87