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// 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/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 data_reduction_proxy {
bool GetDataReductionProxyBypassDuration(
const net::HttpResponseHeaders* headers,
const std::string& action_prefix,
base::TimeDelta* 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.
}
*duration = TimeDelta::FromSeconds(seconds);
return true;
}
}
}
return false;
}
bool GetDataReductionProxyInfo(const net::HttpResponseHeaders* headers,
DataReductionProxyInfo* proxy_info) {
DCHECK(proxy_info);
proxy_info->bypass_all = false;
proxy_info->bypass_duration = TimeDelta();
// 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 (GetDataReductionProxyBypassDuration(
headers, "block=", &proxy_info->bypass_duration)) {
proxy_info->bypass_all = true;
return true;
}
// Next, look for 'bypass'.
if (GetDataReductionProxyBypassDuration(
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::DataReductionProxyBypassEventType
GetDataReductionProxyBypassEventType(
const net::HttpResponseHeaders* headers,
DataReductionProxyInfo* data_reduction_proxy_info) {
DCHECK(data_reduction_proxy_info);
if (GetDataReductionProxyInfo(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.
if (data_reduction_proxy_info->bypass_duration < TimeDelta::FromMinutes(30))
return ProxyService::SHORT_BYPASS;
return ProxyService::LONG_BYPASS;
}
if (headers->response_code() == net::HTTP_INTERNAL_SERVER_ERROR ||
headers->response_code() == net::HTTP_BAD_GATEWAY ||
headers->response_code() == net::HTTP_SERVICE_UNAVAILABLE) {
// Fall back if a 500, 502 or 503 is returned.
return ProxyService::INTERNAL_SERVER_ERROR_BYPASS;
}
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::PROXY_4XX_BYPASS;
}
return ProxyService::MISSING_VIA_HEADER;
}
// There is no bypass event.
return ProxyService::BYPASS_EVENT_TYPE_MAX;
}
} // namespace data_reduction_proxy
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