src/content/renderer/media/cache_util.cc

   1 // Copyright 2013 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 #include "content/renderer/media/cache_util.h"
   6
   7 #include <string>
   8
   9 #include "base/strings/string_number_conversions.h"
  10 #include "base/strings/string_util.h"
  11 #include "base/time/time.h"
  12 #include "net/http/http_util.h"
  13 #include "net/http/http_version.h"
  14 #include "third_party/WebKit/public/platform/WebCString.h"
  15 #include "third_party/WebKit/public/platform/WebString.h"
  16 #include "third_party/WebKit/public/platform/WebURLResponse.h"
  17
  18 using base::Time;
  19 using base::TimeDelta;
  20 using net::HttpVersion;
  21 using WebKit::WebURLResponse;
  22
  23 namespace content {
  24
  25 enum { kHttpOK = 200, kHttpPartialContent = 206 };
  26
  27 uint32 GetReasonsForUncacheability(const WebURLResponse& response) {
  28   uint32 reasons = 0;
  29   const int code = response.httpStatusCode();
  30   const int version = response.httpVersion();
  31   const HttpVersion http_version =
  32       version == WebURLResponse::HTTP_1_1 ? HttpVersion(1, 1) :
  33       version == WebURLResponse::HTTP_1_0 ? HttpVersion(1, 0) :
  34       version == WebURLResponse::HTTP_0_9 ? HttpVersion(0, 9) :
  35       HttpVersion();
  36   if (code != kHttpOK && code != kHttpPartialContent)
  37     reasons |= kNoData;
  38   if (http_version < HttpVersion(1, 1) && code == kHttpPartialContent)
  39     reasons |= kPre11PartialResponse;
  40   if (code == kHttpPartialContent &&
  41       !net::HttpUtil::HasStrongValidators(
  42           http_version,
  43           response.httpHeaderField("etag").utf8(),
  44           response.httpHeaderField("Last-Modified").utf8(),
  45           response.httpHeaderField("Date").utf8())) {
  46     reasons |= kNoStrongValidatorOnPartialResponse;
  47   }
  48
  49   std::string cache_control_header =
  50       response.httpHeaderField("cache-control").utf8();
  51   StringToLowerASCII(&cache_control_header);
  52   if (cache_control_header.find("no-cache") != std::string::npos)
  53     reasons |= kNoCache;
  54   if (cache_control_header.find("no-store") != std::string::npos)
  55     reasons |= kNoStore;
  56   if (cache_control_header.find("must-revalidate") != std::string::npos)
  57     reasons |= kHasMustRevalidate;
  58
  59   const TimeDelta kMinimumAgeForUsefulness =
  60       TimeDelta::FromSeconds(3600);  // Arbitrary value.
  61
  62   const char kMaxAgePrefix[] = "max-age=";
  63   const size_t kMaxAgePrefixLen = arraysize(kMaxAgePrefix) - 1;
  64   if (cache_control_header.substr(0, kMaxAgePrefixLen) == kMaxAgePrefix) {
  65     int64 max_age_seconds;
  66     base::StringToInt64(
  67         base::StringPiece(cache_control_header.begin() + kMaxAgePrefixLen,
  68                           cache_control_header.end()),
  69         &max_age_seconds);
  70     if (TimeDelta::FromSeconds(max_age_seconds) < kMinimumAgeForUsefulness)
  71       reasons |= kShortMaxAge;
  72   }
  73
  74   Time date;
  75   Time expires;
  76   if (Time::FromString(response.httpHeaderField("Date").utf8().data(), &date) &&
  77       Time::FromString(response.httpHeaderField("Expires").utf8().data(),
  78                        &expires) &&
  79       date > Time() && expires > Time() &&
  80       (expires - date) < kMinimumAgeForUsefulness) {
  81     reasons |= kExpiresTooSoon;
  82   }
  83
  84   return reasons;
  85 }
  86
  87 }  // namespace content