services/proxy_resolver_win/windows_system_proxy_resolver_impl.cc - chromium/src - Git at Google

 // Copyright 2020 The Chromium Authors
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include "services/proxy_resolver_win/windows_system_proxy_resolver_impl.h"

 #include <cwchar>
 #include <utility>

 #include "base/functional/bind.h"
 #include "base/logging.h"
 #include "base/memory/raw_ptr.h"
 #include "base/memory/ref_counted.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/task/sequenced_task_runner.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/proxy_server.h"
 #include "net/proxy_resolution/proxy_list.h"
 #include "services/proxy_resolver_win/winhttp_api_wrapper_impl.h"
 #include "url/gurl.h"
 #include "url/url_canon.h"

 namespace proxy_resolver_win {

 namespace {

 bool GetProxyChainFromWinHttpResultEntry(
     const WINHTTP_PROXY_RESULT_ENTRY& result_entry,
     net::ProxyChain* out_proxy_chain) {
   // TODO(https://crbug.com/1032820): Include net logs for proxy bypass
   if (!result_entry.fProxy) {
     *out_proxy_chain = net::ProxyChain::Direct();
     return true;
   }

   net::ProxyServer::Scheme scheme = net::ProxyServer::Scheme::SCHEME_INVALID;
   switch (result_entry.ProxyScheme) {
     case (INTERNET_SCHEME_HTTP):
       scheme = net::ProxyServer::Scheme::SCHEME_HTTP;
       break;
     case (INTERNET_SCHEME_HTTPS):
       scheme = net::ProxyServer::Scheme::SCHEME_HTTPS;
       break;
     case (INTERNET_SCHEME_SOCKS):
       scheme = net::ProxyServer::Scheme::SCHEME_SOCKS4;
       break;
     default:
       LOG(WARNING) << "Of the possible proxy schemes returned by WinHttp, "
                       "Chrome supports HTTP(S) and SOCKS4. The ProxyScheme "
                       "that triggered this message is: "
                    << result_entry.ProxyScheme;
       break;
   }

   if (scheme == net::ProxyServer::Scheme::SCHEME_INVALID)
     return false;

   // Chrome expects a specific port from WinHttp. The WinHttp documentation on
   // MSDN makes it unclear whether or not a specific port is guaranteed.
   if (result_entry.ProxyPort == INTERNET_DEFAULT_PORT) {
     LOG(WARNING) << "WinHttpGetProxyForUrlEx() returned a proxy with "
                     "INTERNET_PORT_DEFAULT!";
     return false;
   }

   // Since there is a proxy in the result (i.e. `fProxy` is TRUE), the
   // `pwszProxy` is guaranteed to be non-null and non-empty.
   DCHECK(!!result_entry.pwszProxy);
   DCHECK(wcslen(result_entry.pwszProxy) > 0);

   std::wstring host_wide(result_entry.pwszProxy,
                          wcslen(result_entry.pwszProxy));
   if (!base::IsStringASCII(host_wide)) {
     const int kInitialBufferSize = 256;
     url::RawCanonOutputT<char16_t, kInitialBufferSize> punycode_output;
     if (!url::IDNToASCII(base::AsStringPiece16(host_wide), &punycode_output)) {
       return false;
     }

     host_wide = base::AsWString(punycode_output.view());
   }

   // At this point the string in `host_wide` is ASCII.
   std::string host;
   if (!base::WideToUTF8(host_wide.data(), host_wide.length(), &host))
     return false;

   net::HostPortPair host_and_port(host, result_entry.ProxyPort);
   *out_proxy_chain = net::ProxyChain(scheme, host_and_port);
   return true;
 }

 }  // namespace

 // Encapsulates an in-flight WinHttp proxy resolution request. This also owns
 // the GetProxyForUrlCallback and will attempt to supply that callback with the
 // proxy result once WinHttp returns.
 class WindowsSystemProxyResolverImpl::Request {
  public:
   Request(WindowsSystemProxyResolverImpl* parent,
           GetProxyForUrlCallback callback);
   Request(const Request&) = delete;
   Request& operator=(const Request&) = delete;
   ~Request();

   // Sets up and kicks off proxy resolution using WinHttp.
   bool Start(const GURL& url);

   base::SequencedTaskRunner* sequenced_task_runner() {
     return sequenced_task_runner_.get();
   }

   // Called from WinHttpStatusCallback on the right sequence. This will make
   // decisions about what to do from the results of the proxy resolution call.
   void DoWinHttpStatusCallback(HINTERNET resolver_handle,
                                DWORD status,
                                int windows_error);

  private:
   // On a successful call to WinHttpGetProxyForUrlEx(), this translates WinHttp
   // results into Chromium-friendly structures and reports the result.
   void GetProxyResultForCallback();

   // Notifies `callback_` of the proxy result.
   void ReportResult(const net::ProxyList& proxy_list,
                     net::WinHttpStatus winhttp_status,
                     int windows_error);

   WinHttpAPIWrapper* winhttp_api_wrapper() {
     return parent_->winhttp_api_wrapper_.get();
   }

   // The WindowsSystemProxyResolverImpl manages the lifetime of this object. The
   // Request cannot outlive the WindowsSystemProxyResolverImpl. Thus, it is safe
   // to hold on to a raw pointer.
   const raw_ptr<WindowsSystemProxyResolverImpl> parent_;
   GetProxyForUrlCallback callback_;
   HINTERNET resolver_handle_;
   scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;

   SEQUENCE_CHECKER(sequence_checker_);
 };

 WindowsSystemProxyResolverImpl::Request::Request(
     WindowsSystemProxyResolverImpl* parent,
     GetProxyForUrlCallback callback)
     : parent_(parent),
       callback_(std::move(callback)),
       resolver_handle_(nullptr),
       sequenced_task_runner_(base::SequencedTaskRunner::GetCurrentDefault()) {}

 WindowsSystemProxyResolverImpl::Request::~Request() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // If the `resolver_handle_` is not null, then there may be an in-flight
   // WinHttp call. This could conceivably happen in some shutdown scenarios. In
   // this case, close the handle to cancel the operation.
   if (resolver_handle_) {
     winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
     resolver_handle_ = nullptr;
   }
 }

 bool WindowsSystemProxyResolverImpl::Request::Start(const GURL& url) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

   // TODO(https://crbug.com/1032820): Use better/distinct net errors.
   net::WinHttpStatus winhttp_status = parent_->EnsureInitialized();
   if (winhttp_status != net::WinHttpStatus::kOk) {
     const int error = GetLastError();
     ReportResult(net::ProxyList(), winhttp_status, error);
     return false;
   }

   // Fetch the current system proxy settings. These are per current network
   // interface and per current user.
   ScopedIEConfig scoped_ie_config;
   if (!winhttp_api_wrapper()->CallWinHttpGetIEProxyConfigForCurrentUser(
           scoped_ie_config.config())) {
     const int error = GetLastError();
     ReportResult(
         net::ProxyList(),
         net::WinHttpStatus::kWinHttpGetIEProxyConfigForCurrentUserFailed,
         error);
     return false;
   }

   // This will create a handle specifically for WinHttpGetProxyForUrlEx().
   if (!winhttp_api_wrapper()->CallWinHttpCreateProxyResolver(
           &resolver_handle_)) {
     const int error = GetLastError();
     ReportResult(net::ProxyList(),
                  net::WinHttpStatus::kWinHttpCreateProxyResolverFailed, error);
     return false;
   }

   // WinHttp will do all necessary proxy resolution fallback for this request.
   // If automatic settings aren't configured or fail, it'll use any manually
   // configured proxies on the machine. The WINHTTP_AUTOPROXY_ALLOW_STATIC flag
   // tells the APIs to pick up manually configured proxies.
   //
   // Separately, Windows allows different proxy settings for different network
   // interfaces. The WINHTTP_AUTOPROXY_ALLOW_CM flag tells WinHttp to
   // differentiate between these settings and to get the proxy that's most
   // specific to the current interface.
   WINHTTP_AUTOPROXY_OPTIONS autoproxy_options = {0};
   autoproxy_options.dwFlags =
       WINHTTP_AUTOPROXY_ALLOW_STATIC | WINHTTP_AUTOPROXY_ALLOW_CM;

   // The fAutoLogonIfChallenged option has been deprecated and should always be
   // set to FALSE throughout Windows 10. Even in earlier versions of the OS,
   // this feature did not work particularly well.
   // https://support.microsoft.com/en-us/help/3161949/ms16-077-description-of-the-security-update-for-wpad-june-14-2016
   autoproxy_options.fAutoLogonIfChallenged = FALSE;

   // Sets a specific PAC URL if there was one in the IE configs.
   if (scoped_ie_config.config()->lpszAutoConfigUrl) {
     autoproxy_options.dwFlags |= WINHTTP_AUTOPROXY_CONFIG_URL;
     autoproxy_options.lpszAutoConfigUrl =
         scoped_ie_config.config()->lpszAutoConfigUrl;
   }

   // Similarly, allow WPAD if it was enabled in the IE configs.
   if (!!scoped_ie_config.config()->fAutoDetect) {
     autoproxy_options.dwFlags |= WINHTTP_AUTOPROXY_AUTO_DETECT;

     // Enable WPAD using both DNS and DHCP, since that is what idiomatic Windows
     // applications do.
     autoproxy_options.dwAutoDetectFlags |= WINHTTP_AUTO_DETECT_TYPE_DNS_A;
     autoproxy_options.dwAutoDetectFlags |= WINHTTP_AUTO_DETECT_TYPE_DHCP;
   }

   // Now that everything is set-up, ask WinHTTP to get the actual proxy list.
   const DWORD_PTR context = reinterpret_cast<DWORD_PTR>(this);
   if (!winhttp_api_wrapper()->CallWinHttpGetProxyForUrlEx(
           resolver_handle_, url.spec(), &autoproxy_options, context)) {
     const int error = GetLastError();
     winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
     resolver_handle_ = nullptr;
     ReportResult(net::ProxyList(),
                  net::WinHttpStatus::kWinHttpGetProxyForURLExFailed, error);
     return false;
   }

   return true;
 }

 void WindowsSystemProxyResolverImpl::Request::DoWinHttpStatusCallback(
     HINTERNET resolver_handle,
     DWORD status,
     int windows_error) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // The `resolver_handle` should correspond to `resolver_handle_`.
   DCHECK_EQ(resolver_handle_, resolver_handle);

   // There is no work to do if this request has been cancelled.
   if (callback_) {
     switch (status) {
       case WINHTTP_CALLBACK_STATUS_GETPROXYFORURL_COMPLETE:
         GetProxyResultForCallback();
         break;
       case WINHTTP_CALLBACK_STATUS_REQUEST_ERROR:
         // TODO(https://crbug.com/1032820): Use a better/distinct net error.
         ReportResult(net::ProxyList(),
                      net::WinHttpStatus::kStatusCallbackFailed, windows_error);
         break;
       default:
         LOG(WARNING) << "DoWinHttpStatusCallback() expects only callbacks for "
                         "WINHTTP_CALLBACK_STATUS_GETPROXYFORURL_COMPLETE and "
                         "WINHTTP_CALLBACK_STATUS_REQUEST_ERROR, not: "
                      << status;
         ReportResult(net::ProxyList(),
                      net::WinHttpStatus::kStatusCallbackFailed, status);
         break;
     }
   }

   // The HINTERNET `resolver_handle_` for this attempt at getting a proxy is no
   // longer needed.
   winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
   resolver_handle_ = nullptr;

   // At this point, the mojo callback has definitely been called.
   DCHECK(callback_.is_null());

   // Now, it's finally safe to delete this object.
   auto it = parent_->requests_.find(this);
   DCHECK(it != parent_->requests_.end());
   parent_->requests_.erase(it);

   // DO NOT ADD ANYTHING BELOW THIS LINE, THE OBJECT HAS NOW BEEN DESTROYED.
 }

 void WindowsSystemProxyResolverImpl::Request::GetProxyResultForCallback() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // TODO(https://crbug.com/1032820): Use better/distinct net errors.
   WINHTTP_PROXY_RESULT proxy_result = {0};
   if (!winhttp_api_wrapper()->CallWinHttpGetProxyResult(resolver_handle_,
                                                         &proxy_result)) {
     const int error = GetLastError();
     ReportResult(net::ProxyList(),
                  net::WinHttpStatus::kWinHttpGetProxyResultFailed, error);
     return;
   }

   // Translate the results for ProxyInfo.
   net::ProxyList proxy_list;
   for (DWORD i = 0u; i < proxy_result.cEntries; ++i) {
     net::ProxyChain proxy_chain;
     if (GetProxyChainFromWinHttpResultEntry(proxy_result.pEntries[i],
                                             &proxy_chain)) {
       proxy_list.AddProxyChain(proxy_chain);
     }
   }

   // The `proxy_result` must be freed.
   winhttp_api_wrapper()->CallWinHttpFreeProxyResult(&proxy_result);

   // The consumer of this proxy resolution may not understand an empty proxy
   // list. Thus, this case is considered an error.
   net::WinHttpStatus winhttp_status = proxy_list.IsEmpty()
                                           ? net::WinHttpStatus::kEmptyProxyList
                                           : net::WinHttpStatus::kOk;
   ReportResult(proxy_list, winhttp_status, 0);
 }

 void WindowsSystemProxyResolverImpl::Request::ReportResult(
     const net::ProxyList& proxy_list,
     net::WinHttpStatus winhttp_status,
     int windows_error) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (!callback_)
     return;

   std::move(callback_).Run(proxy_list, winhttp_status, windows_error);
   callback_.Reset();

   // Even though there are no more mojo calls to make, it is not safe to delete
   // this object yet. To be absolutely sure that WinHttpStatusCallback() does
   // not attempt to dereference a freed object, the only times we delete this
   // object are when we fail to call into WinHttp APIs completely (i.e. we do
   // not expect a callback) and when the WinHttp callback completes in
   // DoWinHttpStatusCallback().
 }

 WindowsSystemProxyResolverImpl::WindowsSystemProxyResolverImpl(
     mojo::PendingReceiver<mojom::WindowsSystemProxyResolver> receiver)
     : receiver_(this, std::move(receiver)) {}
 WindowsSystemProxyResolverImpl::~WindowsSystemProxyResolverImpl() {
   // The WindowsSystemProxyResolverImpl must outlive every Request it owns.
   CHECK(requests_.empty());
 }

 void WindowsSystemProxyResolverImpl::SetCreateWinHttpAPIWrapperForTesting(
     std::unique_ptr<WinHttpAPIWrapper> winhttp_api_wrapper_for_testing) {
   winhttp_api_wrapper_ = std::move(winhttp_api_wrapper_for_testing);
 }

 void WindowsSystemProxyResolverImpl::GetProxyForUrl(
     const GURL& url,
     GetProxyForUrlCallback callback) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   std::unique_ptr<Request> request =
       std::make_unique<Request>(this, std::move(callback));

   // If the request fails to start, it will internally report that to
   // `callback`. After that, it's safe to delete this `request`.
   if (request->Start(url))
     requests_.insert(std::move(request));
 }

 net::WinHttpStatus WindowsSystemProxyResolverImpl::EnsureInitialized() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (initialized_)
     return net::WinHttpStatus::kOk;

   // TODO(https://crbug.com/1032820): Limit the number of times this can
   // fail to initialize.

   // The `winhttp_api_wrapper_` is intended to only get set when initialization
   // is successful. However, it may have been pre-populated via
   // SetCreateWinHttpAPIWrapperForTesting(). In those cases, use that object
   // instead of creating a new one.
   std::unique_ptr<WinHttpAPIWrapper> uninitialized_winhttp_api_wrapper;
   if (winhttp_api_wrapper_) {
     uninitialized_winhttp_api_wrapper = std::move(winhttp_api_wrapper_);
     winhttp_api_wrapper_.reset();
   } else {
     uninitialized_winhttp_api_wrapper =
         std::make_unique<WinHttpAPIWrapperImpl>();
   }

   if (!uninitialized_winhttp_api_wrapper->CallWinHttpOpen())
     return net::WinHttpStatus::kWinHttpOpenFailed;

   // Since this session handle will never be used for WinHTTP connections,
   // these timeouts don't really mean much individually.  However, WinHTTP's
   // out of process PAC resolution will use a combined (sum of all timeouts)
   // value to wait for an RPC reply.
   if (!uninitialized_winhttp_api_wrapper->CallWinHttpSetTimeouts(10000, 10000,
                                                                  5000, 5000)) {
     return net::WinHttpStatus::kWinHttpSetTimeoutsFailed;
   }

   // This sets the entry point for every callback in the WinHttp session created
   // above.
   if (!uninitialized_winhttp_api_wrapper->CallWinHttpSetStatusCallback(
           &WindowsSystemProxyResolverImpl::WinHttpStatusCallback)) {
     return net::WinHttpStatus::kWinHttpSetStatusCallbackFailed;
   }

   initialized_ = true;
   winhttp_api_wrapper_ = std::move(uninitialized_winhttp_api_wrapper);
   return net::WinHttpStatus::kOk;
 }

 // static
 void CALLBACK
 WindowsSystemProxyResolverImpl::WinHttpStatusCallback(HINTERNET resolver_handle,
                                                       DWORD_PTR context,
                                                       DWORD status,
                                                       void* info,
                                                       DWORD info_len) {
   DCHECK(resolver_handle);
   DCHECK(context);
   Request* request = reinterpret_cast<Request*>(context);

   // Make a copy of any error information in `info` so it can be accessed from
   // the subsequently posted task. The `info` pointer's lifetime is managed by
   // WinHTTP and hence is not valid once this frame returns.
   int windows_error = S_OK;
   if (info && status == WINHTTP_CALLBACK_STATUS_REQUEST_ERROR) {
     WINHTTP_ASYNC_RESULT* result = static_cast<WINHTTP_ASYNC_RESULT*>(info);
     windows_error = result->dwError;
   }

   request->sequenced_task_runner()->PostTask(
       FROM_HERE, base::BindOnce(&Request::DoWinHttpStatusCallback,
                                 base::Unretained(request), resolver_handle,
                                 status, windows_error));
 }

 }  // namespace proxy_resolver_win
	// Copyright 2020 The Chromium Authors
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include "services/proxy_resolver_win/windows_system_proxy_resolver_impl.h"

	#include <cwchar>
	#include <utility>

	#include "base/functional/bind.h"
	#include "base/logging.h"
	#include "base/memory/raw_ptr.h"
	#include "base/memory/ref_counted.h"
	#include "base/strings/string_util.h"
	#include "base/strings/utf_string_conversions.h"
	#include "base/task/sequenced_task_runner.h"
	#include "net/base/host_port_pair.h"
	#include "net/base/proxy_server.h"
	#include "net/proxy_resolution/proxy_list.h"
	#include "services/proxy_resolver_win/winhttp_api_wrapper_impl.h"
	#include "url/gurl.h"
	#include "url/url_canon.h"

	namespace proxy_resolver_win {

	namespace {

	bool GetProxyChainFromWinHttpResultEntry(
	const WINHTTP_PROXY_RESULT_ENTRY& result_entry,
	net::ProxyChain* out_proxy_chain) {
	// TODO(https://crbug.com/1032820): Include net logs for proxy bypass
	if (!result_entry.fProxy) {
	*out_proxy_chain = net::ProxyChain::Direct();
	return true;
	}

	net::ProxyServer::Scheme scheme = net::ProxyServer::Scheme::SCHEME_INVALID;
	switch (result_entry.ProxyScheme) {
	case (INTERNET_SCHEME_HTTP):
	scheme = net::ProxyServer::Scheme::SCHEME_HTTP;
	break;
	case (INTERNET_SCHEME_HTTPS):
	scheme = net::ProxyServer::Scheme::SCHEME_HTTPS;
	break;
	case (INTERNET_SCHEME_SOCKS):
	scheme = net::ProxyServer::Scheme::SCHEME_SOCKS4;
	break;
	default:
	LOG(WARNING) << "Of the possible proxy schemes returned by WinHttp, "
	"Chrome supports HTTP(S) and SOCKS4. The ProxyScheme "
	"that triggered this message is: "
	<< result_entry.ProxyScheme;
	break;
	}

	if (scheme == net::ProxyServer::Scheme::SCHEME_INVALID)
	return false;

	// Chrome expects a specific port from WinHttp. The WinHttp documentation on
	// MSDN makes it unclear whether or not a specific port is guaranteed.
	if (result_entry.ProxyPort == INTERNET_DEFAULT_PORT) {
	LOG(WARNING) << "WinHttpGetProxyForUrlEx() returned a proxy with "
	"INTERNET_PORT_DEFAULT!";
	return false;
	}

	// Since there is a proxy in the result (i.e. `fProxy` is TRUE), the
	// `pwszProxy` is guaranteed to be non-null and non-empty.
	DCHECK(!!result_entry.pwszProxy);
	DCHECK(wcslen(result_entry.pwszProxy) > 0);

	std::wstring host_wide(result_entry.pwszProxy,
	wcslen(result_entry.pwszProxy));
	if (!base::IsStringASCII(host_wide)) {
	const int kInitialBufferSize = 256;
	url::RawCanonOutputT<char16_t, kInitialBufferSize> punycode_output;
	if (!url::IDNToASCII(base::AsStringPiece16(host_wide), &punycode_output)) {
	return false;
	}

	host_wide = base::AsWString(punycode_output.view());
	}

	// At this point the string in `host_wide` is ASCII.
	std::string host;
	if (!base::WideToUTF8(host_wide.data(), host_wide.length(), &host))
	return false;

	net::HostPortPair host_and_port(host, result_entry.ProxyPort);
	*out_proxy_chain = net::ProxyChain(scheme, host_and_port);
	return true;
	}

	} // namespace

	// Encapsulates an in-flight WinHttp proxy resolution request. This also owns
	// the GetProxyForUrlCallback and will attempt to supply that callback with the
	// proxy result once WinHttp returns.
	class WindowsSystemProxyResolverImpl::Request {
	public:
	Request(WindowsSystemProxyResolverImpl* parent,
	GetProxyForUrlCallback callback);
	Request(const Request&) = delete;
	Request& operator=(const Request&) = delete;
	~Request();

	// Sets up and kicks off proxy resolution using WinHttp.
	bool Start(const GURL& url);

	base::SequencedTaskRunner* sequenced_task_runner() {
	return sequenced_task_runner_.get();
	}

	// Called from WinHttpStatusCallback on the right sequence. This will make
	// decisions about what to do from the results of the proxy resolution call.
	void DoWinHttpStatusCallback(HINTERNET resolver_handle,
	DWORD status,
	int windows_error);

	private:
	// On a successful call to WinHttpGetProxyForUrlEx(), this translates WinHttp
	// results into Chromium-friendly structures and reports the result.
	void GetProxyResultForCallback();

	// Notifies `callback_` of the proxy result.
	void ReportResult(const net::ProxyList& proxy_list,
	net::WinHttpStatus winhttp_status,
	int windows_error);

	WinHttpAPIWrapper* winhttp_api_wrapper() {
	return parent_->winhttp_api_wrapper_.get();
	}

	// The WindowsSystemProxyResolverImpl manages the lifetime of this object. The
	// Request cannot outlive the WindowsSystemProxyResolverImpl. Thus, it is safe
	// to hold on to a raw pointer.
	const raw_ptr<WindowsSystemProxyResolverImpl> parent_;
	GetProxyForUrlCallback callback_;
	HINTERNET resolver_handle_;
	scoped_refptr<base::SequencedTaskRunner> sequenced_task_runner_;

	SEQUENCE_CHECKER(sequence_checker_);
	};

	WindowsSystemProxyResolverImpl::Request::Request(
	WindowsSystemProxyResolverImpl* parent,
	GetProxyForUrlCallback callback)
	: parent_(parent),
	callback_(std::move(callback)),
	resolver_handle_(nullptr),
	sequenced_task_runner_(base::SequencedTaskRunner::GetCurrentDefault()) {}

	WindowsSystemProxyResolverImpl::Request::~Request() {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	// If the `resolver_handle_` is not null, then there may be an in-flight
	// WinHttp call. This could conceivably happen in some shutdown scenarios. In
	// this case, close the handle to cancel the operation.
	if (resolver_handle_) {
	winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
	resolver_handle_ = nullptr;
	}
	}

	bool WindowsSystemProxyResolverImpl::Request::Start(const GURL& url) {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);

	// TODO(https://crbug.com/1032820): Use better/distinct net errors.
	net::WinHttpStatus winhttp_status = parent_->EnsureInitialized();
	if (winhttp_status != net::WinHttpStatus::kOk) {
	const int error = GetLastError();
	ReportResult(net::ProxyList(), winhttp_status, error);
	return false;
	}

	// Fetch the current system proxy settings. These are per current network
	// interface and per current user.
	ScopedIEConfig scoped_ie_config;
	if (!winhttp_api_wrapper()->CallWinHttpGetIEProxyConfigForCurrentUser(
	scoped_ie_config.config())) {
	const int error = GetLastError();
	ReportResult(
	net::ProxyList(),
	net::WinHttpStatus::kWinHttpGetIEProxyConfigForCurrentUserFailed,
	error);
	return false;
	}

	// This will create a handle specifically for WinHttpGetProxyForUrlEx().
	if (!winhttp_api_wrapper()->CallWinHttpCreateProxyResolver(
	&resolver_handle_)) {
	const int error = GetLastError();
	ReportResult(net::ProxyList(),
	net::WinHttpStatus::kWinHttpCreateProxyResolverFailed, error);
	return false;
	}

	// WinHttp will do all necessary proxy resolution fallback for this request.
	// If automatic settings aren't configured or fail, it'll use any manually
	// configured proxies on the machine. The WINHTTP_AUTOPROXY_ALLOW_STATIC flag
	// tells the APIs to pick up manually configured proxies.
	//
	// Separately, Windows allows different proxy settings for different network
	// interfaces. The WINHTTP_AUTOPROXY_ALLOW_CM flag tells WinHttp to
	// differentiate between these settings and to get the proxy that's most
	// specific to the current interface.
	WINHTTP_AUTOPROXY_OPTIONS autoproxy_options = {0};
	autoproxy_options.dwFlags =
	WINHTTP_AUTOPROXY_ALLOW_STATIC \| WINHTTP_AUTOPROXY_ALLOW_CM;

	// The fAutoLogonIfChallenged option has been deprecated and should always be
	// set to FALSE throughout Windows 10. Even in earlier versions of the OS,
	// this feature did not work particularly well.
	// https://support.microsoft.com/en-us/help/3161949/ms16-077-description-of-the-security-update-for-wpad-june-14-2016
	autoproxy_options.fAutoLogonIfChallenged = FALSE;

	// Sets a specific PAC URL if there was one in the IE configs.
	if (scoped_ie_config.config()->lpszAutoConfigUrl) {
	autoproxy_options.dwFlags \|= WINHTTP_AUTOPROXY_CONFIG_URL;
	autoproxy_options.lpszAutoConfigUrl =
	scoped_ie_config.config()->lpszAutoConfigUrl;
	}

	// Similarly, allow WPAD if it was enabled in the IE configs.
	if (!!scoped_ie_config.config()->fAutoDetect) {
	autoproxy_options.dwFlags \|= WINHTTP_AUTOPROXY_AUTO_DETECT;

	// Enable WPAD using both DNS and DHCP, since that is what idiomatic Windows
	// applications do.
	autoproxy_options.dwAutoDetectFlags \|= WINHTTP_AUTO_DETECT_TYPE_DNS_A;
	autoproxy_options.dwAutoDetectFlags \|= WINHTTP_AUTO_DETECT_TYPE_DHCP;
	}

	// Now that everything is set-up, ask WinHTTP to get the actual proxy list.
	const DWORD_PTR context = reinterpret_cast<DWORD_PTR>(this);
	if (!winhttp_api_wrapper()->CallWinHttpGetProxyForUrlEx(
	resolver_handle_, url.spec(), &autoproxy_options, context)) {
	const int error = GetLastError();
	winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
	resolver_handle_ = nullptr;
	ReportResult(net::ProxyList(),
	net::WinHttpStatus::kWinHttpGetProxyForURLExFailed, error);
	return false;
	}

	return true;
	}

	void WindowsSystemProxyResolverImpl::Request::DoWinHttpStatusCallback(
	HINTERNET resolver_handle,
	DWORD status,
	int windows_error) {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	// The `resolver_handle` should correspond to `resolver_handle_`.
	DCHECK_EQ(resolver_handle_, resolver_handle);

	// There is no work to do if this request has been cancelled.
	if (callback_) {
	switch (status) {
	case WINHTTP_CALLBACK_STATUS_GETPROXYFORURL_COMPLETE:
	GetProxyResultForCallback();
	break;
	case WINHTTP_CALLBACK_STATUS_REQUEST_ERROR:
	// TODO(https://crbug.com/1032820): Use a better/distinct net error.
	ReportResult(net::ProxyList(),
	net::WinHttpStatus::kStatusCallbackFailed, windows_error);
	break;
	default:
	LOG(WARNING) << "DoWinHttpStatusCallback() expects only callbacks for "
	"WINHTTP_CALLBACK_STATUS_GETPROXYFORURL_COMPLETE and "
	"WINHTTP_CALLBACK_STATUS_REQUEST_ERROR, not: "
	<< status;
	ReportResult(net::ProxyList(),
	net::WinHttpStatus::kStatusCallbackFailed, status);
	break;
	}
	}

	// The HINTERNET `resolver_handle_` for this attempt at getting a proxy is no
	// longer needed.
	winhttp_api_wrapper()->CallWinHttpCloseHandle(resolver_handle_);
	resolver_handle_ = nullptr;

	// At this point, the mojo callback has definitely been called.
	DCHECK(callback_.is_null());

	// Now, it's finally safe to delete this object.
	auto it = parent_->requests_.find(this);
	DCHECK(it != parent_->requests_.end());
	parent_->requests_.erase(it);

	// DO NOT ADD ANYTHING BELOW THIS LINE, THE OBJECT HAS NOW BEEN DESTROYED.
	}

	void WindowsSystemProxyResolverImpl::Request::GetProxyResultForCallback() {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	// TODO(https://crbug.com/1032820): Use better/distinct net errors.
	WINHTTP_PROXY_RESULT proxy_result = {0};
	if (!winhttp_api_wrapper()->CallWinHttpGetProxyResult(resolver_handle_,
	&proxy_result)) {
	const int error = GetLastError();
	ReportResult(net::ProxyList(),
	net::WinHttpStatus::kWinHttpGetProxyResultFailed, error);
	return;
	}

	// Translate the results for ProxyInfo.
	net::ProxyList proxy_list;
	for (DWORD i = 0u; i < proxy_result.cEntries; ++i) {
	net::ProxyChain proxy_chain;
	if (GetProxyChainFromWinHttpResultEntry(proxy_result.pEntries[i],
	&proxy_chain)) {
	proxy_list.AddProxyChain(proxy_chain);
	}
	}

	// The `proxy_result` must be freed.
	winhttp_api_wrapper()->CallWinHttpFreeProxyResult(&proxy_result);

	// The consumer of this proxy resolution may not understand an empty proxy
	// list. Thus, this case is considered an error.
	net::WinHttpStatus winhttp_status = proxy_list.IsEmpty()
	? net::WinHttpStatus::kEmptyProxyList
	: net::WinHttpStatus::kOk;
	ReportResult(proxy_list, winhttp_status, 0);
	}

	void WindowsSystemProxyResolverImpl::Request::ReportResult(
	const net::ProxyList& proxy_list,
	net::WinHttpStatus winhttp_status,
	int windows_error) {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	if (!callback_)
	return;

	std::move(callback_).Run(proxy_list, winhttp_status, windows_error);
	callback_.Reset();

	// Even though there are no more mojo calls to make, it is not safe to delete
	// this object yet. To be absolutely sure that WinHttpStatusCallback() does
	// not attempt to dereference a freed object, the only times we delete this
	// object are when we fail to call into WinHttp APIs completely (i.e. we do
	// not expect a callback) and when the WinHttp callback completes in
	// DoWinHttpStatusCallback().
	}

	WindowsSystemProxyResolverImpl::WindowsSystemProxyResolverImpl(
	mojo::PendingReceiver<mojom::WindowsSystemProxyResolver> receiver)
	: receiver_(this, std::move(receiver)) {}
	WindowsSystemProxyResolverImpl::~WindowsSystemProxyResolverImpl() {
	// The WindowsSystemProxyResolverImpl must outlive every Request it owns.
	CHECK(requests_.empty());
	}

	void WindowsSystemProxyResolverImpl::SetCreateWinHttpAPIWrapperForTesting(
	std::unique_ptr<WinHttpAPIWrapper> winhttp_api_wrapper_for_testing) {
	winhttp_api_wrapper_ = std::move(winhttp_api_wrapper_for_testing);
	}

	void WindowsSystemProxyResolverImpl::GetProxyForUrl(
	const GURL& url,
	GetProxyForUrlCallback callback) {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	std::unique_ptr<Request> request =
	std::make_unique<Request>(this, std::move(callback));

	// If the request fails to start, it will internally report that to
	// `callback`. After that, it's safe to delete this `request`.
	if (request->Start(url))
	requests_.insert(std::move(request));
	}

	net::WinHttpStatus WindowsSystemProxyResolverImpl::EnsureInitialized() {
	DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
	if (initialized_)
	return net::WinHttpStatus::kOk;

	// TODO(https://crbug.com/1032820): Limit the number of times this can
	// fail to initialize.

	// The `winhttp_api_wrapper_` is intended to only get set when initialization
	// is successful. However, it may have been pre-populated via
	// SetCreateWinHttpAPIWrapperForTesting(). In those cases, use that object
	// instead of creating a new one.
	std::unique_ptr<WinHttpAPIWrapper> uninitialized_winhttp_api_wrapper;
	if (winhttp_api_wrapper_) {
	uninitialized_winhttp_api_wrapper = std::move(winhttp_api_wrapper_);
	winhttp_api_wrapper_.reset();
	} else {
	uninitialized_winhttp_api_wrapper =
	std::make_unique<WinHttpAPIWrapperImpl>();
	}

	if (!uninitialized_winhttp_api_wrapper->CallWinHttpOpen())
	return net::WinHttpStatus::kWinHttpOpenFailed;

	// Since this session handle will never be used for WinHTTP connections,
	// these timeouts don't really mean much individually. However, WinHTTP's
	// out of process PAC resolution will use a combined (sum of all timeouts)
	// value to wait for an RPC reply.
	if (!uninitialized_winhttp_api_wrapper->CallWinHttpSetTimeouts(10000, 10000,
	5000, 5000)) {
	return net::WinHttpStatus::kWinHttpSetTimeoutsFailed;
	}

	// This sets the entry point for every callback in the WinHttp session created
	// above.
	if (!uninitialized_winhttp_api_wrapper->CallWinHttpSetStatusCallback(
	&WindowsSystemProxyResolverImpl::WinHttpStatusCallback)) {
	return net::WinHttpStatus::kWinHttpSetStatusCallbackFailed;
	}

	initialized_ = true;
	winhttp_api_wrapper_ = std::move(uninitialized_winhttp_api_wrapper);
	return net::WinHttpStatus::kOk;
	}

	// static
	void CALLBACK
	WindowsSystemProxyResolverImpl::WinHttpStatusCallback(HINTERNET resolver_handle,
	DWORD_PTR context,
	DWORD status,
	void* info,
	DWORD info_len) {
	DCHECK(resolver_handle);
	DCHECK(context);
	Request* request = reinterpret_cast<Request*>(context);

	// Make a copy of any error information in `info` so it can be accessed from
	// the subsequently posted task. The `info` pointer's lifetime is managed by
	// WinHTTP and hence is not valid once this frame returns.
	int windows_error = S_OK;
	if (info && status == WINHTTP_CALLBACK_STATUS_REQUEST_ERROR) {
	WINHTTP_ASYNC_RESULT* result = static_cast<WINHTTP_ASYNC_RESULT*>(info);
	windows_error = result->dwError;
	}

	request->sequenced_task_runner()->PostTask(
	FROM_HERE, base::BindOnce(&Request::DoWinHttpStatusCallback,
	base::Unretained(request), resolver_handle,
	status, windows_error));
	}

	} // namespace proxy_resolver_win