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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "content/browser/preloading/prefetch/prefetch_proxy_configurator.h"
#include "base/barrier_closure.h"
#include "base/metrics/histogram_functions.h"
#include "base/rand_util.h"
#include "base/time/default_clock.h"
#include "content/browser/preloading/prefetch/prefetch_features.h"
#include "content/browser/preloading/prefetch/prefetch_params.h"
#include "net/base/host_port_pair.h"
#include "net/base/proxy_chain.h"
#include "net/base/proxy_string_util.h"
#include "net/http/http_status_code.h"
#include "net/http/http_util.h"
#include "net/proxy_resolution/proxy_config.h"
#include "url/gurl.h"
namespace content {
// static
std::unique_ptr<PrefetchProxyConfigurator>
PrefetchProxyConfigurator::MaybeCreatePrefetchProxyConfigurator(
const GURL& proxy_url,
const std::string& api_key) {
if (!base::FeatureList::IsEnabled(features::kPrefetchProxy)) {
return nullptr;
}
if (!proxy_url.is_valid())
return nullptr;
return std::make_unique<PrefetchProxyConfigurator>(proxy_url, api_key);
}
PrefetchProxyConfigurator::PrefetchProxyConfigurator(const GURL& proxy_url,
const std::string& api_key)
: prefetch_proxy_chain_(net::GetSchemeFromUriScheme(proxy_url.scheme()),
net::HostPortPair::FromURL(proxy_url)),
clock_(base::DefaultClock::GetInstance()) {
DCHECK(proxy_url.is_valid());
std::string server_experiment_group = PrefetchProxyServerExperimentGroup();
std::string header_value =
"key=" + api_key +
(server_experiment_group != "" ? ",exp=" + server_experiment_group : "");
connect_tunnel_headers_.SetHeader("chrome-tunnel", header_value);
}
PrefetchProxyConfigurator::~PrefetchProxyConfigurator() = default;
void PrefetchProxyConfigurator::SetClockForTesting(const base::Clock* clock) {
clock_ = clock;
}
void PrefetchProxyConfigurator::AddCustomProxyConfigClient(
mojo::Remote<network::mojom::CustomProxyConfigClient> config_client,
base::OnceCallback<void()> callback) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
proxy_config_clients_.Add(std::move(config_client));
UpdateCustomProxyConfig(std::move(callback));
}
void PrefetchProxyConfigurator::UpdateCustomProxyConfig(
base::OnceCallback<void()> callback) {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
base::RepeatingClosure repeating_closure =
base::BarrierClosure(proxy_config_clients_.size(), std::move(callback));
network::mojom::CustomProxyConfigPtr config = CreateCustomProxyConfig();
for (auto& client : proxy_config_clients_) {
client->OnCustomProxyConfigUpdated(config->Clone(), repeating_closure);
}
}
network::mojom::CustomProxyConfigPtr
PrefetchProxyConfigurator::CreateCustomProxyConfig() const {
DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
auto config = network::mojom::CustomProxyConfig::New();
config->rules.type =
net::ProxyConfig::ProxyRules::Type::PROXY_LIST_PER_SCHEME;
// DIRECT is intentionally not added here because we want the proxy to always
// be used in order to mask the user's IP address during the prerender.
config->rules.proxies_for_https.AddProxyChain(prefetch_proxy_chain_);
// This ensures that the user's set proxy is honored, although we also disable
// the feature is such cases.
config->should_override_existing_config = false;
config->allow_non_idempotent_methods = false;
config->connect_tunnel_headers = connect_tunnel_headers_;
return config;
}
mojo::PendingRemote<network::mojom::CustomProxyConnectionObserver>
PrefetchProxyConfigurator::NewProxyConnectionObserverRemote() {
mojo::PendingRemote<network::mojom::CustomProxyConnectionObserver>
observer_remote;
observer_receivers_.Add(this,
observer_remote.InitWithNewPipeAndPassReceiver());
// The disconnect handler is intentionally not set since ReceiverSet manages
// connection clean up on disconnect.
return observer_remote;
}
void PrefetchProxyConfigurator::OnFallback(const net::ProxyChain& bad_chain,
int net_error) {
if (bad_chain != prefetch_proxy_chain_) {
return;
}
base::UmaHistogramSparse("PrefetchProxy.Proxy.Fallback.NetError",
std::abs(net_error));
OnTunnelProxyConnectionError(std::nullopt);
}
void PrefetchProxyConfigurator::OnTunnelHeadersReceived(
const net::ProxyChain& proxy_chain,
uint64_t chain_index,
const scoped_refptr<net::HttpResponseHeaders>& response_headers) {
DCHECK(response_headers);
if (proxy_chain != prefetch_proxy_chain_) {
return;
}
base::UmaHistogramSparse("PrefetchProxy.Proxy.RespCode",
response_headers->response_code());
if (response_headers->response_code() == net::HTTP_OK) {
return;
}
std::string retry_after_string;
if (response_headers->EnumerateHeader(nullptr, "Retry-After",
&retry_after_string)) {
base::TimeDelta retry_after;
if (net::HttpUtil::ParseRetryAfterHeader(retry_after_string, clock_->Now(),
&retry_after)) {
OnTunnelProxyConnectionError(retry_after);
return;
}
}
OnTunnelProxyConnectionError(std::nullopt);
}
bool PrefetchProxyConfigurator::IsPrefetchProxyAvailable() const {
if (!prefetch_proxy_not_available_until_) {
return true;
}
return prefetch_proxy_not_available_until_.value() <= clock_->Now();
}
void PrefetchProxyConfigurator::OnTunnelProxyConnectionError(
std::optional<base::TimeDelta> retry_after) {
base::Time retry_proxy_at;
if (retry_after) {
retry_proxy_at = clock_->Now() + *retry_after;
} else {
// Pick a random value between 1-5 mins if the proxy didn't give us a
// Retry-After value. The randomness will help ensure there is no sudden
// wave of requests following a proxy error.
retry_proxy_at = clock_->Now() + base::Seconds(base::RandInt(
base::Time::kSecondsPerMinute,
5 * base::Time::kSecondsPerMinute));
}
DCHECK(!retry_proxy_at.is_null());
// If there is already a value in |prefetch_proxy_not_available_until_|,
// probably due to some race, take the max.
if (prefetch_proxy_not_available_until_) {
prefetch_proxy_not_available_until_ =
std::max(*prefetch_proxy_not_available_until_, retry_proxy_at);
} else {
prefetch_proxy_not_available_until_ = retry_proxy_at;
}
DCHECK(prefetch_proxy_not_available_until_);
// TODO(crbug.com/40152136): Consider persisting to prefs.
}
} // namespace content
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