1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
|
// Copyright 2014 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.
#include "components/data_reduction_proxy/common/data_reduction_proxy_headers.h"
#include <string>
#include "base/rand_util.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/string_piece.h"
#include "base/strings/string_util.h"
#include "base/time/time.h"
#include "net/http/http_response_headers.h"
#include "net/http/http_status_code.h"
#include "net/proxy/proxy_service.h"
using base::StringPiece;
using base::TimeDelta;
using net::ProxyService;
namespace {
const int kShortBypassMaxSeconds = 59;
const int kMediumBypassMaxSeconds = 300;
// Returns a random bypass duration between 1 and 5 minutes.
base::TimeDelta GetDefaultBypassDuration() {
const int64 delta_ms =
base::RandInt(base::TimeDelta::FromMinutes(1).InMilliseconds(),
base::TimeDelta::FromMinutes(5).InMilliseconds());
return TimeDelta::FromMilliseconds(delta_ms);
}
} // namespace
namespace data_reduction_proxy {
bool ParseHeadersAndSetBypassDuration(const net::HttpResponseHeaders* headers,
const std::string& action_prefix,
base::TimeDelta* bypass_duration) {
void* iter = NULL;
std::string value;
std::string name = "chrome-proxy";
while (headers->EnumerateHeader(&iter, name, &value)) {
if (value.size() > action_prefix.size()) {
if (LowerCaseEqualsASCII(value.begin(),
value.begin() + action_prefix.size(),
action_prefix.c_str())) {
int64 seconds;
if (!base::StringToInt64(
StringPiece(value.begin() + action_prefix.size(), value.end()),
&seconds) || seconds < 0) {
continue; // In case there is a well formed instruction.
}
if (seconds != 0) {
*bypass_duration = TimeDelta::FromSeconds(seconds);
} else {
// Server deferred to us to choose a duration. Default to a random
// duration between one and five minutes.
*bypass_duration = GetDefaultBypassDuration();
}
return true;
}
}
}
return false;
}
bool ParseHeadersAndSetProxyInfo(const net::HttpResponseHeaders* headers,
DataReductionProxyInfo* proxy_info) {
DCHECK(proxy_info);
proxy_info->bypass_all = false;
// Support header of the form Chrome-Proxy: bypass|block=<duration>, where
// <duration> is the number of seconds to wait before retrying
// the proxy. If the duration is 0, then the default proxy retry delay
// (specified in |ProxyList::UpdateRetryInfoOnFallback|) will be used.
// 'bypass' instructs Chrome to bypass the currently connected data reduction
// proxy, whereas 'block' instructs Chrome to bypass all available data
// reduction proxies.
// 'block' takes precedence over 'bypass', so look for it first.
// TODO(bengr): Reduce checks for 'block' and 'bypass' to a single loop.
if (ParseHeadersAndSetBypassDuration(
headers, "block=", &proxy_info->bypass_duration)) {
proxy_info->bypass_all = true;
return true;
}
// Next, look for 'bypass'.
if (ParseHeadersAndSetBypassDuration(
headers, "bypass=", &proxy_info->bypass_duration)) {
return true;
}
return false;
}
bool HasDataReductionProxyViaHeader(const net::HttpResponseHeaders* headers) {
const size_t kVersionSize = 4;
const char kDataReductionProxyViaValue[] = "Chrome-Compression-Proxy";
size_t value_len = strlen(kDataReductionProxyViaValue);
void* iter = NULL;
std::string value;
// Case-sensitive comparison of |value|. Assumes the received protocol and the
// space following it are always |kVersionSize| characters. E.g.,
// 'Via: 1.1 Chrome-Compression-Proxy'
while (headers->EnumerateHeader(&iter, "via", &value)) {
if (value.size() >= kVersionSize + value_len &&
!value.compare(kVersionSize, value_len, kDataReductionProxyViaValue))
return true;
}
// TODO(bengr): Remove deprecated header value.
const char kDeprecatedDataReductionProxyViaValue[] =
"1.1 Chrome Compression Proxy";
iter = NULL;
while (headers->EnumerateHeader(&iter, "via", &value))
if (value == kDeprecatedDataReductionProxyViaValue)
return true;
return false;
}
net::ProxyService::DataReductionProxyBypassType
GetDataReductionProxyBypassType(
const net::HttpResponseHeaders* headers,
DataReductionProxyInfo* data_reduction_proxy_info) {
DCHECK(data_reduction_proxy_info);
if (ParseHeadersAndSetProxyInfo(headers, data_reduction_proxy_info)) {
// A chrome-proxy response header is only present in a 502. For proper
// reporting, this check must come before the 5xx checks below.
const TimeDelta& duration = data_reduction_proxy_info->bypass_duration;
if (duration <= TimeDelta::FromSeconds(kShortBypassMaxSeconds))
return ProxyService::SHORT_BYPASS;
if (duration <= TimeDelta::FromSeconds(kMediumBypassMaxSeconds))
return ProxyService::MEDIUM_BYPASS;
return ProxyService::LONG_BYPASS;
}
data_reduction_proxy_info->bypass_duration = GetDefaultBypassDuration();
// Fall back if a 500, 502 or 503 is returned.
if (headers->response_code() == net::HTTP_INTERNAL_SERVER_ERROR)
return ProxyService::STATUS_500_HTTP_INTERNAL_SERVER_ERROR;
if (headers->response_code() == net::HTTP_BAD_GATEWAY)
return ProxyService::STATUS_502_HTTP_BAD_GATEWAY;
if (headers->response_code() == net::HTTP_SERVICE_UNAVAILABLE)
return ProxyService::STATUS_503_HTTP_SERVICE_UNAVAILABLE;
// TODO(kundaji): Bypass if Proxy-Authenticate header value cannot be
// interpreted by data reduction proxy.
if (headers->response_code() == net::HTTP_PROXY_AUTHENTICATION_REQUIRED &&
!headers->HasHeader("Proxy-Authenticate")) {
return ProxyService::MALFORMED_407;
}
if (!HasDataReductionProxyViaHeader(headers) &&
(headers->response_code() != net::HTTP_NOT_MODIFIED)) {
// A Via header might not be present in a 304. Since the goal of a 304
// response is to minimize information transfer, a sender in general
// should not generate representation metadata other than Cache-Control,
// Content-Location, Date, ETag, Expires, and Vary.
// The proxy Via header might also not be present in a 4xx response.
// Separate this case from other responses that are missing the header.
if (headers->response_code() >= net::HTTP_BAD_REQUEST &&
headers->response_code() < net::HTTP_INTERNAL_SERVER_ERROR) {
return ProxyService::MISSING_VIA_HEADER_4XX;
}
return ProxyService::MISSING_VIA_HEADER_OTHER;
}
// There is no bypass event.
return ProxyService::BYPASS_EVENT_TYPE_MAX;
}
} // namespace data_reduction_proxy
|
