1 // Copyright 2014 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 "components/data_reduction_proxy/common/data_reduction_proxy_headers.h"
6
7 #include <string>
8
9 #include "base/strings/string_number_conversions.h"
10 #include "base/strings/string_piece.h"
11 #include "base/strings/string_util.h"
12 #include "base/time/time.h"
13 #include "net/http/http_response_headers.h"
14 #include "net/http/http_status_code.h"
15 #include "net/proxy/proxy_service.h"
16
17 using base::StringPiece;
18 using base::TimeDelta;
19 using net::ProxyService;
20
21 namespace data_reduction_proxy {
22
GetDataReductionProxyBypassDuration(const net::HttpResponseHeaders * headers,const std::string & action_prefix,base::TimeDelta * duration)23 bool GetDataReductionProxyBypassDuration(
24 const net::HttpResponseHeaders* headers,
25 const std::string& action_prefix,
26 base::TimeDelta* duration) {
27 void* iter = NULL;
28 std::string value;
29 std::string name = "chrome-proxy";
30
31 while (headers->EnumerateHeader(&iter, name, &value)) {
32 if (value.size() > action_prefix.size()) {
33 if (LowerCaseEqualsASCII(value.begin(),
34 value.begin() + action_prefix.size(),
35 action_prefix.c_str())) {
36 int64 seconds;
37 if (!base::StringToInt64(
38 StringPiece(value.begin() + action_prefix.size(), value.end()),
39 &seconds) || seconds < 0) {
40 continue; // In case there is a well formed instruction.
41 }
42 *duration = TimeDelta::FromSeconds(seconds);
43 return true;
44 }
45 }
46 }
47 return false;
48 }
49
GetDataReductionProxyInfo(const net::HttpResponseHeaders * headers,DataReductionProxyInfo * proxy_info)50 bool GetDataReductionProxyInfo(const net::HttpResponseHeaders* headers,
51 DataReductionProxyInfo* proxy_info) {
52 DCHECK(proxy_info);
53 proxy_info->bypass_all = false;
54 proxy_info->bypass_duration = TimeDelta();
55 // Support header of the form Chrome-Proxy: bypass|block=<duration>, where
56 // <duration> is the number of seconds to wait before retrying
57 // the proxy. If the duration is 0, then the default proxy retry delay
58 // (specified in |ProxyList::UpdateRetryInfoOnFallback|) will be used.
59 // 'bypass' instructs Chrome to bypass the currently connected data reduction
60 // proxy, whereas 'block' instructs Chrome to bypass all available data
61 // reduction proxies.
62
63 // 'block' takes precedence over 'bypass', so look for it first.
64 // TODO(bengr): Reduce checks for 'block' and 'bypass' to a single loop.
65 if (GetDataReductionProxyBypassDuration(
66 headers, "block=", &proxy_info->bypass_duration)) {
67 proxy_info->bypass_all = true;
68 return true;
69 }
70
71 // Next, look for 'bypass'.
72 if (GetDataReductionProxyBypassDuration(
73 headers, "bypass=", &proxy_info->bypass_duration)) {
74 return true;
75 }
76 return false;
77 }
78
HasDataReductionProxyViaHeader(const net::HttpResponseHeaders * headers)79 bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers) {
80 const size_t kVersionSize = 4;
81 const char kDataReductionProxyViaValue[] = "Chrome-Compression-Proxy";
82 size_t value_len = strlen(kDataReductionProxyViaValue);
83 void* iter = NULL;
84 std::string value;
85
86 // Case-sensitive comparison of |value|. Assumes the received protocol and the
87 // space following it are always |kVersionSize| characters. E.g.,
88 // 'Via: 1.1 Chrome-Compression-Proxy'
89 while (headers->EnumerateHeader(&iter, "via", &value)) {
90 if (value.size() >= kVersionSize + value_len &&
91 !value.compare(kVersionSize, value_len, kDataReductionProxyViaValue))
92 return true;
93 }
94
95 // TODO(bengr): Remove deprecated header value.
96 const char kDeprecatedDataReductionProxyViaValue[] =
97 "1.1 Chrome Compression Proxy";
98 iter = NULL;
99 while (headers->EnumerateHeader(&iter, "via", &value))
100 if (value == kDeprecatedDataReductionProxyViaValue)
101 return true;
102
103 return false;
104 }
105
106 net::ProxyService::DataReductionProxyBypassEventType
GetDataReductionProxyBypassEventType(const net::HttpResponseHeaders * headers,DataReductionProxyInfo * data_reduction_proxy_info)107 GetDataReductionProxyBypassEventType(
108 const net::HttpResponseHeaders* headers,
109 DataReductionProxyInfo* data_reduction_proxy_info) {
110 DCHECK(data_reduction_proxy_info);
111 if (GetDataReductionProxyInfo(headers, data_reduction_proxy_info)) {
112 // A chrome-proxy response header is only present in a 502. For proper
113 // reporting, this check must come before the 5xx checks below.
114 if (data_reduction_proxy_info->bypass_duration < TimeDelta::FromMinutes(30))
115 return ProxyService::SHORT_BYPASS;
116 return ProxyService::LONG_BYPASS;
117 }
118 if (headers->response_code() == net::HTTP_INTERNAL_SERVER_ERROR ||
119 headers->response_code() == net::HTTP_BAD_GATEWAY ||
120 headers->response_code() == net::HTTP_SERVICE_UNAVAILABLE) {
121 // Fall back if a 500, 502 or 503 is returned.
122 return ProxyService::INTERNAL_SERVER_ERROR_BYPASS;
123 }
124 // TODO(kundaji): Bypass if Proxy-Authenticate header value cannot be
125 // interpreted by data reduction proxy.
126 if (headers->response_code() == net::HTTP_PROXY_AUTHENTICATION_REQUIRED &&
127 !headers->HasHeader("Proxy-Authenticate")) {
128 return ProxyService::MALFORMED_407_BYPASS;
129 }
130 if (!HasDataReductionProxyViaHeader(headers) &&
131 (headers->response_code() != net::HTTP_NOT_MODIFIED)) {
132 // A Via header might not be present in a 304. Since the goal of a 304
133 // response is to minimize information transfer, a sender in general
134 // should not generate representation metadata other than Cache-Control,
135 // Content-Location, Date, ETag, Expires, and Vary.
136
137 // The proxy Via header might also not be present in a 4xx response.
138 // Separate this case from other responses that are missing the header.
139 if (headers->response_code() >= net::HTTP_BAD_REQUEST &&
140 headers->response_code() < net::HTTP_INTERNAL_SERVER_ERROR) {
141 return ProxyService::PROXY_4XX_BYPASS;
142 }
143 return ProxyService::MISSING_VIA_HEADER;
144 }
145 // There is no bypass event.
146 return ProxyService::BYPASS_EVENT_TYPE_MAX;
147 }
148
149 } // namespace data_reduction_proxy
150