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- // Copyright (c) 2012 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 "net/proxy_resolution/pac_file_fetcher_impl.h"
- #include "base/bind.h"
- #include "base/compiler_specific.h"
- #include "base/location.h"
- #include "base/logging.h"
- #include "base/memory/ptr_util.h"
- #include "base/metrics/histogram_macros.h"
- #include "base/ranges/algorithm.h"
- #include "base/strings/string_piece.h"
- #include "base/strings/string_util.h"
- #include "base/task/single_thread_task_runner.h"
- #include "base/threading/thread_task_runner_handle.h"
- #include "net/base/data_url.h"
- #include "net/base/io_buffer.h"
- #include "net/base/load_flags.h"
- #include "net/base/net_errors.h"
- #include "net/base/net_string_util.h"
- #include "net/base/request_priority.h"
- #include "net/cert/cert_status_flags.h"
- #include "net/http/http_response_headers.h"
- #include "net/url_request/redirect_info.h"
- #include "net/url_request/url_request_context.h"
- // TODO(eroman):
- // - Support auth-prompts (http://crbug.com/77366)
- namespace net {
- namespace {
- // The maximum size (in bytes) allowed for a PAC script. Responses exceeding
- // this will fail with ERR_FILE_TOO_BIG.
- const int kDefaultMaxResponseBytes = 1048576; // 1 megabyte
- // The maximum duration (in milliseconds) allowed for fetching the PAC script.
- // Responses exceeding this will fail with ERR_TIMED_OUT.
- //
- // This timeout applies to both scripts fetched in the course of WPAD, as well
- // as explicitly configured ones.
- //
- // If the default timeout is too high, auto-detect can stall for a long time,
- // and if it is too low then slow loading scripts may be skipped.
- //
- // 30 seconds is a compromise between those competing goals. This value also
- // appears to match Microsoft Edge (based on testing).
- constexpr base::TimeDelta kDefaultMaxDuration = base::Seconds(30);
- // Returns true if |mime_type| is one of the known PAC mime type.
- constexpr bool IsPacMimeType(base::StringPiece mime_type) {
- constexpr base::StringPiece kSupportedPacMimeTypes[] = {
- "application/x-ns-proxy-autoconfig",
- "application/x-javascript-config",
- };
- return base::ranges::any_of(kSupportedPacMimeTypes, [&](auto pac_mime_type) {
- return base::EqualsCaseInsensitiveASCII(pac_mime_type, mime_type);
- });
- }
- struct BomMapping {
- base::StringPiece prefix;
- const char* charset;
- };
- const BomMapping kBomMappings[] = {
- {"\xFE\xFF", "utf-16be"},
- {"\xFF\xFE", "utf-16le"},
- {"\xEF\xBB\xBF", "utf-8"},
- };
- // Converts |bytes| (which is encoded by |charset|) to UTF16, saving the resul
- // to |*utf16|.
- // If |charset| is empty, then we don't know what it was and guess.
- void ConvertResponseToUTF16(const std::string& charset,
- const std::string& bytes,
- std::u16string* utf16) {
- if (charset.empty()) {
- // Guess the charset by looking at the BOM.
- base::StringPiece bytes_str(bytes);
- for (const auto& bom : kBomMappings) {
- if (base::StartsWith(bytes_str, bom.prefix)) {
- return ConvertResponseToUTF16(
- bom.charset,
- // Strip the BOM in the converted response.
- bytes.substr(bom.prefix.size()), utf16);
- }
- }
- // Otherwise assume ISO-8859-1 if no charset was specified.
- return ConvertResponseToUTF16(kCharsetLatin1, bytes, utf16);
- }
- DCHECK(!charset.empty());
- // Be generous in the conversion -- if any characters lie outside of |charset|
- // (i.e. invalid), then substitute them with U+FFFD rather than failing.
- ConvertToUTF16WithSubstitutions(bytes, charset.c_str(), utf16);
- }
- } // namespace
- std::unique_ptr<PacFileFetcherImpl> PacFileFetcherImpl::Create(
- URLRequestContext* url_request_context) {
- return base::WrapUnique(new PacFileFetcherImpl(url_request_context));
- }
- PacFileFetcherImpl::~PacFileFetcherImpl() {
- // The URLRequest's destructor will cancel the outstanding request, and
- // ensure that the delegate (this) is not called again.
- }
- base::TimeDelta PacFileFetcherImpl::SetTimeoutConstraint(
- base::TimeDelta timeout) {
- base::TimeDelta prev = max_duration_;
- max_duration_ = timeout;
- return prev;
- }
- size_t PacFileFetcherImpl::SetSizeConstraint(size_t size_bytes) {
- size_t prev = max_response_bytes_;
- max_response_bytes_ = size_bytes;
- return prev;
- }
- void PacFileFetcherImpl::OnResponseCompleted(URLRequest* request,
- int net_error) {
- DCHECK_EQ(request, cur_request_.get());
- // Use |result_code_| as the request's error if we have already set it to
- // something specific.
- if (result_code_ == OK && net_error != OK)
- result_code_ = net_error;
- FetchCompleted();
- }
- int PacFileFetcherImpl::Fetch(
- const GURL& url,
- std::u16string* text,
- CompletionOnceCallback callback,
- const NetworkTrafficAnnotationTag traffic_annotation) {
- // It is invalid to call Fetch() while a request is already in progress.
- DCHECK(!cur_request_.get());
- DCHECK(!callback.is_null());
- DCHECK(text);
- if (!url_request_context_)
- return ERR_CONTEXT_SHUT_DOWN;
- if (!IsUrlSchemeAllowed(url))
- return ERR_DISALLOWED_URL_SCHEME;
- // Handle base-64 encoded data-urls that contain custom PAC scripts.
- if (url.SchemeIs("data")) {
- std::string mime_type;
- std::string charset;
- std::string data;
- if (!DataURL::Parse(url, &mime_type, &charset, &data))
- return ERR_FAILED;
- ConvertResponseToUTF16(charset, data, text);
- return OK;
- }
- DCHECK(fetch_start_time_.is_null());
- fetch_start_time_ = base::TimeTicks::Now();
- // Use highest priority, so if socket pools are being used for other types of
- // requests, PAC requests are aren't blocked on them.
- cur_request_ = url_request_context_->CreateRequest(url, MAXIMUM_PRIORITY,
- this, traffic_annotation);
- cur_request_->set_isolation_info(isolation_info());
- // Make sure that the PAC script is downloaded using a direct connection,
- // to avoid circular dependencies (fetching is a part of proxy resolution).
- // Also disable the use of the disk cache. The cache is disabled so that if
- // the user switches networks we don't potentially use the cached response
- // from old network when we should in fact be re-fetching on the new network.
- // If the PAC script is hosted on an HTTPS server we bypass revocation
- // checking in order to avoid a circular dependency when attempting to fetch
- // the OCSP response or CRL. We could make the revocation check go direct but
- // the proxy might be the only way to the outside world. IGNORE_LIMITS is
- // used to avoid blocking proxy resolution on other network requests.
- cur_request_->SetLoadFlags(LOAD_BYPASS_PROXY | LOAD_DISABLE_CACHE |
- LOAD_DISABLE_CERT_NETWORK_FETCHES |
- LOAD_IGNORE_LIMITS);
- // Save the caller's info for notification on completion.
- callback_ = std::move(callback);
- result_text_ = text;
- bytes_read_so_far_.clear();
- // Post a task to timeout this request if it takes too long.
- cur_request_id_ = ++next_id_;
- base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
- FROM_HERE,
- base::BindOnce(&PacFileFetcherImpl::OnTimeout, weak_factory_.GetWeakPtr(),
- cur_request_id_),
- max_duration_);
- // Start the request.
- cur_request_->Start();
- return ERR_IO_PENDING;
- }
- void PacFileFetcherImpl::Cancel() {
- // ResetCurRequestState will free the URLRequest, which will cause
- // cancellation.
- ResetCurRequestState();
- }
- URLRequestContext* PacFileFetcherImpl::GetRequestContext() const {
- return url_request_context_;
- }
- void PacFileFetcherImpl::OnShutdown() {
- url_request_context_ = nullptr;
- if (cur_request_) {
- result_code_ = ERR_CONTEXT_SHUT_DOWN;
- FetchCompleted();
- }
- }
- void PacFileFetcherImpl::OnReceivedRedirect(URLRequest* request,
- const RedirectInfo& redirect_info,
- bool* defer_redirect) {
- int error = OK;
- // Redirection to file:// is never OK. Ordinarily this is handled lower in the
- // stack (|FileProtocolHandler::IsSafeRedirectTarget|), but this is reachable
- // when built without file:// suppport. Return the same error for consistency.
- if (redirect_info.new_url.SchemeIsFile()) {
- error = ERR_UNSAFE_REDIRECT;
- } else if (!IsUrlSchemeAllowed(redirect_info.new_url)) {
- error = ERR_DISALLOWED_URL_SCHEME;
- }
- if (error != OK) {
- // Fail the redirect.
- request->CancelWithError(error);
- OnResponseCompleted(request, error);
- }
- }
- void PacFileFetcherImpl::OnAuthRequired(URLRequest* request,
- const AuthChallengeInfo& auth_info) {
- DCHECK_EQ(request, cur_request_.get());
- // TODO(eroman): http://crbug.com/77366
- LOG(WARNING) << "Auth required to fetch PAC script, aborting.";
- result_code_ = ERR_NOT_IMPLEMENTED;
- request->CancelAuth();
- }
- void PacFileFetcherImpl::OnSSLCertificateError(URLRequest* request,
- int net_error,
- const SSLInfo& ssl_info,
- bool fatal) {
- DCHECK_EQ(request, cur_request_.get());
- LOG(WARNING) << "SSL certificate error when fetching PAC script, aborting.";
- // Certificate errors are in same space as net errors.
- result_code_ = net_error;
- request->Cancel();
- }
- void PacFileFetcherImpl::OnResponseStarted(URLRequest* request, int net_error) {
- DCHECK_EQ(request, cur_request_.get());
- DCHECK_NE(ERR_IO_PENDING, net_error);
- if (net_error != OK) {
- OnResponseCompleted(request, net_error);
- return;
- }
- // Require HTTP responses to have a success status code.
- if (request->url().SchemeIsHTTPOrHTTPS()) {
- // NOTE about status codes: We are like Firefox 3 in this respect.
- // {IE 7, Safari 3, Opera 9.5} do not care about the status code.
- if (request->GetResponseCode() != 200) {
- VLOG(1) << "Fetched PAC script had (bad) status line: "
- << request->response_headers()->GetStatusLine();
- result_code_ = ERR_HTTP_RESPONSE_CODE_FAILURE;
- request->Cancel();
- return;
- }
- // NOTE about mime types: We do not enforce mime types on PAC files.
- // This is for compatibility with {IE 7, Firefox 3, Opera 9.5}. We will
- // however log mismatches to help with debugging.
- std::string mime_type;
- cur_request_->GetMimeType(&mime_type);
- if (!IsPacMimeType(mime_type)) {
- VLOG(1) << "Fetched PAC script does not have a proper mime type: "
- << mime_type;
- }
- }
- ReadBody(request);
- }
- void PacFileFetcherImpl::OnReadCompleted(URLRequest* request, int num_bytes) {
- DCHECK_NE(ERR_IO_PENDING, num_bytes);
- DCHECK_EQ(request, cur_request_.get());
- if (ConsumeBytesRead(request, num_bytes)) {
- // Keep reading.
- ReadBody(request);
- }
- }
- PacFileFetcherImpl::PacFileFetcherImpl(URLRequestContext* url_request_context)
- : url_request_context_(url_request_context),
- buf_(base::MakeRefCounted<IOBuffer>(kBufSize)),
- max_response_bytes_(kDefaultMaxResponseBytes),
- max_duration_(kDefaultMaxDuration) {
- DCHECK(url_request_context);
- }
- bool PacFileFetcherImpl::IsUrlSchemeAllowed(const GURL& url) const {
- // Always allow http://, https://, and data:.
- if (url.SchemeIsHTTPOrHTTPS() || url.SchemeIs("data"))
- return true;
- // Disallow any other URL scheme.
- return false;
- }
- void PacFileFetcherImpl::ReadBody(URLRequest* request) {
- // Read as many bytes as are available synchronously.
- while (true) {
- int num_bytes = request->Read(buf_.get(), kBufSize);
- if (num_bytes == ERR_IO_PENDING)
- return;
- if (num_bytes < 0) {
- OnResponseCompleted(request, num_bytes);
- return;
- }
- if (!ConsumeBytesRead(request, num_bytes))
- return;
- }
- }
- bool PacFileFetcherImpl::ConsumeBytesRead(URLRequest* request, int num_bytes) {
- if (fetch_time_to_first_byte_.is_null())
- fetch_time_to_first_byte_ = base::TimeTicks::Now();
- if (num_bytes <= 0) {
- // Error while reading, or EOF.
- OnResponseCompleted(request, num_bytes);
- return false;
- }
- // Enforce maximum size bound.
- if (num_bytes + bytes_read_so_far_.size() >
- static_cast<size_t>(max_response_bytes_)) {
- result_code_ = ERR_FILE_TOO_BIG;
- request->Cancel();
- return false;
- }
- bytes_read_so_far_.append(buf_->data(), num_bytes);
- return true;
- }
- void PacFileFetcherImpl::FetchCompleted() {
- if (result_code_ == OK) {
- // Calculate duration of time for PAC file fetch to complete.
- DCHECK(!fetch_start_time_.is_null());
- DCHECK(!fetch_time_to_first_byte_.is_null());
- UMA_HISTOGRAM_MEDIUM_TIMES("Net.ProxyScriptFetcher.SuccessDuration",
- base::TimeTicks::Now() - fetch_start_time_);
- UMA_HISTOGRAM_MEDIUM_TIMES("Net.ProxyScriptFetcher.FirstByteDuration",
- fetch_time_to_first_byte_ - fetch_start_time_);
- // The caller expects the response to be encoded as UTF16.
- std::string charset;
- cur_request_->GetCharset(&charset);
- ConvertResponseToUTF16(charset, bytes_read_so_far_, result_text_);
- } else {
- // On error, the caller expects empty string for bytes.
- result_text_->clear();
- }
- int result_code = result_code_;
- CompletionOnceCallback callback = std::move(callback_);
- ResetCurRequestState();
- std::move(callback).Run(result_code);
- }
- void PacFileFetcherImpl::ResetCurRequestState() {
- cur_request_.reset();
- cur_request_id_ = 0;
- callback_.Reset();
- result_code_ = OK;
- result_text_ = nullptr;
- fetch_start_time_ = base::TimeTicks();
- fetch_time_to_first_byte_ = base::TimeTicks();
- }
- void PacFileFetcherImpl::OnTimeout(int id) {
- // Timeout tasks may outlive the URLRequest they reference. Make sure it
- // is still applicable.
- if (cur_request_id_ != id)
- return;
- DCHECK(cur_request_.get());
- result_code_ = ERR_TIMED_OUT;
- FetchCompleted();
- }
- } // namespace net
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