Initial import of the Chrome Frame codebase. Integration in chrome.gyp coming...

chrome_frame/urlmon_url_request.cc

Index: chrome_frame/urlmon_url_request.cc
===================================================================
--- chrome_frame/urlmon_url_request.cc	(revision 0)
+++ chrome_frame/urlmon_url_request.cc	(revision 0)
@@ -0,0 +1,751 @@
+// Copyright (c) 2009 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 "chrome_frame/urlmon_url_request.h"
+
+#include <wininet.h>
+
+#include "base/scoped_ptr.h"
+#include "base/string_util.h"
+#include "base/logging.h"
+#include "chrome_frame/urlmon_upload_data_stream.h"
+#include "net/http/http_util.h"
+#include "net/http/http_response_headers.h"
+
+static const LARGE_INTEGER kZero = {0};
+static const ULARGE_INTEGER kUnsignedZero = {0};
+int UrlmonUrlRequest::instance_count_ = 0;
+const char kXFrameOptionsHeader[] = "X-Frame-Options";
+
+UrlmonUrlRequest::UrlmonUrlRequest()
+    : pending_read_size_(0),
+      status_(URLRequestStatus::FAILED, net::ERR_FAILED),
+      thread_(PlatformThread::CurrentId()),
+      is_request_started_(false),
+      post_data_len_(0),
+      redirect_status_(0),
+      parent_window_(NULL) {
+  DLOG(INFO) << StringPrintf("Created request. Obj: %X", this)
+      << " Count: " << ++instance_count_;
+}
+
+UrlmonUrlRequest::~UrlmonUrlRequest() {
+  DLOG(INFO) << StringPrintf("Deleted request. Obj: %X", this)
+      << " Count: " << --instance_count_;
+}
+
+bool UrlmonUrlRequest::Start() {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  status_.set_status(URLRequestStatus::IO_PENDING);
+  HRESULT hr = StartAsyncDownload();
+  if (FAILED(hr)) {
+    // Do not call EndRequest() here since it will attempt to free references
+    // that have not been established.
+    status_.set_os_error(HresultToNetError(hr));
+    status_.set_status(URLRequestStatus::FAILED);
+    DLOG(ERROR) << "StartAsyncDownload failed";
+    OnResponseEnd(status_);
+    return false;
+  }
+
+  // Take a self reference to maintain COM lifetime. This will be released
+  // in EndRequest. Set a flag indicating that we have an additional
+  // reference here
+  is_request_started_ = true;
+  AddRef();
+  request_handler()->AddRequest(this);
+  return true;
+}
+
+void UrlmonUrlRequest::Stop() {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  if (binding_) {
+    binding_->Abort();
+  } else {
+    status_.set_status(URLRequestStatus::CANCELED);
+    status_.set_os_error(net::ERR_FAILED);
+    EndRequest();
+  }
+}
+
+bool UrlmonUrlRequest::Read(int bytes_to_read) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this);
+
+  // Send cached data if available.
+  CComObjectStackEx<SendStream> send_stream;
+  send_stream.Initialize(this);
+  size_t bytes_copied = 0;
+  if (cached_data_.is_valid() && cached_data_.Read(&send_stream, bytes_to_read,
+                                                   &bytes_copied)) {
+    DLOG(INFO) << StringPrintf("URL: %s Obj: %X - bytes read from cache: %d",
+                               url().c_str(), this, bytes_copied);
+    return true;
+  }
+
+  // if the request is finished or there's nothing more to read
+  // then end the request
+  if (!status_.is_io_pending() || !binding_) {
+    DLOG(INFO) << StringPrintf("URL: %s Obj: %X. Response finished. Status: %d",
+                               url().c_str(), this, status_.status());
+    EndRequest();
+    return true;
+  }
+
+  pending_read_size_ = bytes_to_read;
+  DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+      "- Read pending for: " << bytes_to_read;
+  return true;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnStartBinding(
+    DWORD reserved, IBinding *binding) {
+  binding_ = binding;
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::GetPriority(LONG *priority) {
+  if (!priority)
+    return E_POINTER;
+  *priority = THREAD_PRIORITY_NORMAL;
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnLowResource(DWORD reserved) {
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnProgress(ULONG progress, ULONG max_progress,
+    ULONG status_code, LPCWSTR status_text) {
+  switch (status_code) {
+    case BINDSTATUS_REDIRECTING:
+      DCHECK(status_text != NULL);
+      DLOG(INFO) << "URL: " << url() << " redirected to "
+                 << status_text;
+      redirect_url_ = status_text;
+      // Fetch the redirect status as they aren't all equal (307 in particular
+      // retains the HTTP request verb).
+      redirect_status_ = GetHttpResponseStatus();
+      break;
+
+    default:
+      DLOG(INFO) << " Obj: " << std::hex << this << " OnProgress(" << url()
+          << StringPrintf(L") code: %i status: %ls", status_code, status_text);
+      break;
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnStopBinding(HRESULT result, LPCWSTR error) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+      " - Request stopped, Result: " << std::hex << result <<
+      " Status: " << status_.status();
+  if (FAILED(result)) {
+    status_.set_status(URLRequestStatus::FAILED);
+    status_.set_os_error(HresultToNetError(result));
+    EndRequest();
+  } else {
+    status_.set_status(URLRequestStatus::SUCCESS);
+    status_.set_os_error(0);
+  }
+
+  // Release these variables after reporting EndRequest since we might need to
+  // access their state.
+  binding_ = NULL;
+  bind_context_ = NULL;
+
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::GetBindInfo(DWORD* bind_flags,
+    BINDINFO *bind_info) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  if ((bind_info == NULL) || (bind_info->cbSize == 0) || (bind_flags == NULL))
+    return E_INVALIDARG;
+
+  *bind_flags = BINDF_ASYNCHRONOUS | BINDF_ASYNCSTORAGE | BINDF_PULLDATA;
+  if (LowerCaseEqualsASCII(method(), "get")) {
+    bind_info->dwBindVerb = BINDVERB_GET;
+  } else if (LowerCaseEqualsASCII(method(), "post")) {
+    bind_info->dwBindVerb = BINDVERB_POST;
+
+    // Bypass caching proxies on POSTs and avoid writing responses to POST
+    // requests to the browser's cache.
+    *bind_flags |= BINDF_GETNEWESTVERSION | BINDF_NOWRITECACHE |
+                   BINDF_PRAGMA_NO_CACHE;
+
+    // Initialize the STGMEDIUM.
+    memset(&bind_info->stgmedData, 0, sizeof(STGMEDIUM));
+    bind_info->grfBindInfoF = 0;
+    bind_info->szCustomVerb = NULL;
+
+    scoped_refptr<net::UploadData> upload_data(upload_data());
+    post_data_len_ = upload_data.get() ? upload_data->GetContentLength() : 0;
+    if (post_data_len_) {
+      DLOG(INFO) << " Obj: " << std::hex << this << " POST request with "
+          << Int64ToString(post_data_len_) << " bytes";
+      CComObject<UrlmonUploadDataStream>* upload_stream = NULL;
+      HRESULT hr =
+          CComObject<UrlmonUploadDataStream>::CreateInstance(&upload_stream);
+      if (FAILED(hr)) {
+        NOTREACHED();
+        return hr;
+      }
+      upload_stream->Initialize(upload_data.get());
+
+      // Fill the STGMEDIUM with the data to post
+      bind_info->stgmedData.tymed = TYMED_ISTREAM;
+      bind_info->stgmedData.pstm = static_cast<IStream*>(upload_stream);
+      bind_info->stgmedData.pstm->AddRef();
+    } else {
+      DLOG(INFO) << " Obj: " << std::hex << this
+          << "POST request with no data!";
+    }
+  } else {
+    NOTREACHED() << "Unknown HTTP method.";
+    status_.set_status(URLRequestStatus::FAILED);
+    status_.set_os_error(net::ERR_INVALID_URL);
+    EndRequest();
+    return E_FAIL;
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnDataAvailable(DWORD flags, DWORD size,
+                                               FORMATETC* formatetc,
+                                               STGMEDIUM* storage) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+  DLOG(INFO) << StringPrintf("URL: %s Obj: %X - Bytes available: %d",
+                             url().c_str(), this, size);
+
+  if (!storage || (storage->tymed != TYMED_ISTREAM)) {
+    NOTREACHED();
+    return E_INVALIDARG;
+  }
+
+  IStream* read_stream = storage->pstm;
+  if (!read_stream) {
+    NOTREACHED();
+    return E_UNEXPECTED;
+  }
+
+  HRESULT hr = S_OK;
+  if (BSCF_FIRSTDATANOTIFICATION & flags) {
+    DCHECK(!cached_data_.is_valid());
+    cached_data_.Create();
+  }
+
+  // Always read data into cache. We have to read all the data here at this
+  // time or it won't be available later. Since the size of the data could
+  // be more than pending read size, it's not straightforward (or might even
+  // be impossible) to implement a true data pull model.
+  size_t bytes_available = 0;
+  cached_data_.Append(read_stream, &bytes_available);
+  DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+      " -  Bytes read into cache: " << bytes_available;
+
+  if (pending_read_size_) {
+    CComObjectStackEx<SendStream> send_stream;
+    send_stream.Initialize(this);
+    cached_data_.Read(&send_stream, pending_read_size_, &pending_read_size_);
+    DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+        " - size read: " << pending_read_size_;
+    pending_read_size_ = 0;
+  } else {
+    DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+        " - waiting for remote read";
+  }
+
+  if (BSCF_LASTDATANOTIFICATION & flags) {
+    status_.set_status(URLRequestStatus::SUCCESS);
+    DLOG(INFO) << StringPrintf("URL: %s Obj: %X", url().c_str(), this) <<
+        " - end of data.";
+  }
+
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnObjectAvailable(REFIID iid, IUnknown *object) {
+  // We are calling BindToStorage on the moniker we should always get called
+  // back on OnDataAvailable and should never get OnObjectAvailable
+  NOTREACHED();
+  return E_NOTIMPL;
+}
+
+STDMETHODIMP UrlmonUrlRequest::BeginningTransaction(const wchar_t* url,
+    const wchar_t* current_headers, DWORD reserved,
+    wchar_t** additional_headers) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+  if (!additional_headers) {
+    NOTREACHED();
+    return E_POINTER;
+  }
+
+  DLOG(INFO) << "URL: " << url << " Obj: " << std::hex << this <<
+      " - Request headers: \n" << current_headers;
+
+  HRESULT hr = S_OK;
+
+  std::string new_headers;
+  if (post_data_len_ > 0) {
+    // Tack on the Content-Length header since when using an IStream type
+    // STGMEDIUM, it looks like it doesn't get set for us :(
+    new_headers = StringPrintf("Content-Length: %s\r\n",
+                               Int64ToString(post_data_len_).c_str());
+  }
+
+  if (!extra_headers().empty()) {
+    // TODO(robertshield): We may need to sanitize headers on POST here.
+    new_headers += extra_headers();
+  }
+
+  if (!referrer().empty()) {
+    // Referrer is famously misspelled in HTTP:
+    new_headers += StringPrintf("Referer: %s\r\n", referrer().c_str());
+  }
+
+  if (!new_headers.empty()) {
+    *additional_headers = reinterpret_cast<wchar_t*>(
+        CoTaskMemAlloc((new_headers.size() + 1) * sizeof(wchar_t)));
+
+    if (*additional_headers == NULL) {
+      NOTREACHED();
+      hr = E_OUTOFMEMORY;
+    } else {
+      lstrcpynW(*additional_headers, ASCIIToWide(new_headers).c_str(),
+                new_headers.size());
+    }
+  }
+
+  return hr;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnResponse(DWORD dwResponseCode,
+    const wchar_t* response_headers, const wchar_t* request_headers,
+    wchar_t** additional_headers) {
+  DCHECK_EQ(PlatformThread::CurrentId(), thread_);
+
+  std::string raw_headers = WideToUTF8(response_headers);
+
+  // Security check for frame busting headers. We don't honor the headers
+  // as-such, but instead simply kill requests which we've been asked to 
+  // look for. This puts the onus on the user of the UrlRequest to specify 
+  // whether or not requests should be inspected. For ActiveDocuments, the 
+  // answer is "no", since WebKit's detection/handling is sufficient and since 
+  // ActiveDocuments cannot be hosted as iframes. For NPAPI and ActiveX 
+  // documents, the Initialize() function of the PluginUrlRequest object 
+  // allows them to specify how they'd like requests handled. Both should 
+  // set enable_frame_busting_ to true to avoid CSRF attacks.
+  // Should WebKit's handling of this ever change, we will need to re-visit 
+  // how and when frames are killed to better mirror a policy which may 
+  // do something other than kill the sub-document outright.
+
+  // NOTE(slightlyoff): We don't use net::HttpResponseHeaders here because 
+  //    of lingering ICU/base_noicu issues.
+  if (frame_busting_enabled_ &&
+      net::HttpUtil::HasHeader(raw_headers, kXFrameOptionsHeader)) {
+    DLOG(ERROR) << "X-Frame-Options header detected, navigation canceled";
+    return E_FAIL;
+  }
+
+  std::wstring url_for_persistent_cookies =
+      redirect_url_.empty() ? UTF8ToWide(url()) : redirect_url_;
+
+  std::string persistent_cookies;
+
+  DWORD cookie_size = 0;  // NOLINT
+  InternetGetCookie(url_for_persistent_cookies.c_str(), NULL, NULL,
+                    &cookie_size);
+  if (cookie_size) {
+    scoped_ptr<wchar_t> cookies(new wchar_t[cookie_size + 1]);
+    if (!InternetGetCookie(url_for_persistent_cookies.c_str(), NULL,
+                           cookies.get(), &cookie_size)) {
+      NOTREACHED() << "InternetGetCookie failed. Error: " << GetLastError();
+    } else {
+      persistent_cookies = WideToUTF8(cookies.get());
+    }
+  }
+
+  OnResponseStarted("",
+                    raw_headers.c_str(),
+                    0,
+                    base::Time(),
+                    persistent_cookies,
+                    redirect_url_.empty() ? std::string() :
+                        WideToUTF8(redirect_url_),
+                    redirect_status_);
+
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::GetWindow(const GUID& guid_reason,
+                                         HWND* parent_window) {
+  if (!parent_window) {
+    return E_INVALIDARG;
+  }
+
+#ifndef NDEBUG
+  wchar_t guid[40] = {0};
+  ::StringFromGUID2(guid_reason, guid, arraysize(guid));
+
+  DLOG(INFO) << " Obj: " << std::hex << this << " GetWindow: " <<
+      (guid_reason == IID_IAuthenticate ? L" - IAuthenticate" :
+       (guid_reason == IID_IHttpSecurity ? L"IHttpSecurity" :
+        (guid_reason == IID_IWindowForBindingUI ? L"IWindowForBindingUI" :
+                                                  guid)));
+#endif
+
+  // TODO(iyengar): This hits when running the URL request tests.
+  DLOG_IF(ERROR, !::IsWindow(parent_window_))
+      << "UrlmonUrlRequest::GetWindow - no window!";
+  *parent_window = parent_window_;
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::Authenticate(HWND* parent_window,
+                                            LPWSTR* user_name,
+                                            LPWSTR* password) {
+  if (!parent_window) {
+    return E_INVALIDARG;
+  }
+
+  DCHECK(::IsWindow(parent_window_));
+  *parent_window = parent_window_;
+  return S_OK;
+}
+
+STDMETHODIMP UrlmonUrlRequest::OnSecurityProblem(DWORD problem) {
+  // Urlmon notifies the client of authentication problems, certificate
+  // errors, etc by querying the object implementing the IBindStatusCallback
+  // interface for the IHttpSecurity interface. If this interface is not
+  // implemented then Urlmon checks for the problem codes defined below
+  // and performs actions as defined below:-
+  // It invokes the ReportProgress method of the protocol sink with
+  // these problem codes and eventually invokes the ReportResult method
+  // on the protocol sink which ends up in a call to the OnStopBinding
+  // method of the IBindStatusCallBack interface.
+
+  // MSHTML's implementation of the IBindStatusCallback interface does not
+  // implement the IHttpSecurity interface. However it handles the
+  // OnStopBinding call with a HRESULT of 0x800c0019 and navigates to
+  // an interstitial page which presents the user with a choice of whether
+  // to abort the navigation.
+
+  // In our OnStopBinding implementation we stop the navigation and inform
+  // Chrome about the result. Ideally Chrome should behave in a manner similar
+  // to IE, i.e. display the SSL error interstitial page and if the user
+  // decides to proceed anyway we would turn off SSL warnings for that
+  // particular navigation and allow IE to download the content.
+  // We would need to return the certificate information to Chrome for display
+  // purposes. Currently we only return a dummy certificate to Chrome.
+  // At this point we decided that it is a lot of work at this point and
+  // decided to go with the easier option of implementing the IHttpSecurity
+  // interface and replicating the checks performed by Urlmon. This
+  // causes Urlmon to display a dialog box on the same lines as IE6.
+  DLOG(INFO) << __FUNCTION__ << " Security problem : " << problem;
+
+  HRESULT hr = E_ABORT;
+
+  switch (problem) {
+    case ERROR_INTERNET_SEC_CERT_REV_FAILED: {
+      hr = RPC_E_RETRY;
+      break;
+    }
+
+    case ERROR_INTERNET_SEC_CERT_DATE_INVALID:
+    case ERROR_INTERNET_SEC_CERT_CN_INVALID:
+    case ERROR_INTERNET_INVALID_CA: {
+      hr = S_FALSE;
+      break;
+    }
+
+    default: {
+      NOTREACHED() << "Unhandled security problem : " << problem;
+      break;
+    }
+  }
+  return hr;
+}
+
+HRESULT UrlmonUrlRequest::ConnectToExistingMoniker(IMoniker* moniker,
+                                                   IBindCtx* context,
+                                                   const std::wstring& url) {
+  if (!moniker || url.empty()) {
+    NOTREACHED() << "Invalid arguments";
+    return E_INVALIDARG;
+  }
+
+  DCHECK(moniker_.get() == NULL);
+  DCHECK(bind_context_.get() == NULL);
+
+  moniker_ = moniker;
+  bind_context_ = context;
+  set_url(WideToUTF8(url));
+  return S_OK;
+}
+
+HRESULT UrlmonUrlRequest::StartAsyncDownload() {
+  HRESULT hr = E_FAIL;
+  if (moniker_.get() == NULL) {
+    std::wstring wide_url = UTF8ToWide(url());
+    hr = CreateURLMonikerEx(NULL, wide_url.c_str(), moniker_.Receive(),
+                            URL_MK_UNIFORM);
+    if (FAILED(hr)) {
+      NOTREACHED() << "CreateURLMonikerEx failed. Error: " << hr;
+    } else {
+      hr = CreateAsyncBindCtx(0, this, NULL, bind_context_.Receive());
+      DCHECK(SUCCEEDED(hr)) << "CreateAsyncBindCtx failed. Error: " << hr;
+    }
+  } else {
+    DCHECK(bind_context_.get() != NULL);
+    hr = RegisterBindStatusCallback(bind_context_, this, NULL, 0);
+  }
+
+  if (SUCCEEDED(hr)) {
+    ScopedComPtr<IStream> stream;
+    hr = moniker_->BindToStorage(bind_context_, NULL, __uuidof(IStream),
+                                 reinterpret_cast<void**>(stream.Receive()));
+    if (FAILED(hr)) {
+      // TODO(joshia): Look into. This currently fails for:
+      // http://user2:secret@localhost:1337/auth-basic?set-cookie-if-challenged
+      // when running the UrlRequest unit tests.
+      DLOG(ERROR) <<
+          StringPrintf("IUrlMoniker::BindToStorage failed. Error: 0x%08X.", hr)
+          << std::endl << url();
+      DCHECK(hr == MK_E_SYNTAX);
+    }
+  }
+
+  DLOG_IF(ERROR, FAILED(hr))
+      << StringPrintf(L"StartAsyncDownload failed: 0x%08X", hr);
+
+  return hr;
+}
+
+void UrlmonUrlRequest::EndRequest() {
+  DLOG(INFO) << __FUNCTION__;
+  // Special case.  If the last request was a redirect and the current OS
+  // error value is E_ACCESSDENIED, that means an unsafe redirect was attempted.
+  // In that case, correct the OS error value to be the more specific
+  // ERR_UNSAFE_REDIRECT error value.
+  if (!status_.is_success() && status_.os_error() == net::ERR_ACCESS_DENIED) {
+    int status = GetHttpResponseStatus();
+    if (status >= 300 && status < 400) {
+      redirect_status_ = status;  // store the latest redirect status value.
+      status_.set_os_error(net::ERR_UNSAFE_REDIRECT);
+    }
+  }
+  request_handler()->RemoveRequest(this);
+  OnResponseEnd(status_);
+
+  // If the request was started then we must have an additional reference on the
+  // request.
+  if (is_request_started_) {
+    is_request_started_ = false;
+    Release();
+  }
+}
+
+int UrlmonUrlRequest::GetHttpResponseStatus() const {
+  if (binding_ == NULL) {
+    DLOG(WARNING) << "GetHttpResponseStatus - no binding_";
+    return 0;
+  }
+
+  int http_status = 0;
+
+  ScopedComPtr<IWinInetHttpInfo> info;
+  if (SUCCEEDED(info.QueryFrom(binding_))) {
+    char status[10] = {0};
+    DWORD buf_size = sizeof(status);
+    if (SUCCEEDED(info->QueryInfo(HTTP_QUERY_STATUS_CODE, status, &buf_size,
+                                  0, NULL))) {
+      http_status = StringToInt(status);
+    } else {
+      NOTREACHED() << "Failed to get HTTP status";
+    }
+  } else {
+    NOTREACHED() << "failed to get IWinInetHttpInfo from binding_";
+  }
+
+  return http_status;
+}
+
+//
+// UrlmonUrlRequest::Cache implementation.
+//
+
+size_t UrlmonUrlRequest::Cache::Size() {
+  size_t size = 0;
+  if (stream_) {
+    STATSTG cache_stat = {0};
+    stream_->Stat(&cache_stat, STATFLAG_NONAME);
+
+    DCHECK_EQ(0, cache_stat.cbSize.HighPart);
+    size = cache_stat.cbSize.LowPart;
+  }
+
+  return size;
+}
+
+size_t UrlmonUrlRequest::Cache::CurrentPos() {
+  size_t pos = 0;
+  if (stream_) {
+    ULARGE_INTEGER current_index = {0};
+    stream_->Seek(kZero, STREAM_SEEK_CUR, &current_index);
+
+    DCHECK_EQ(0, current_index.HighPart);
+    pos = current_index.LowPart;
+  }
+
+  return pos;
+}
+
+size_t UrlmonUrlRequest::Cache::SizeRemaining() {
+  size_t size = Size();
+  size_t pos = CurrentPos();
+  size_t size_remaining = 0;
+
+  if (size) {
+    DCHECK(pos <= size);
+    size_remaining = size - pos;
+  }
+  return size_remaining;
+}
+
+void UrlmonUrlRequest::Cache::Clear() {
+  if (!stream_) {
+    NOTREACHED();
+    return;
+  }
+
+  HRESULT hr = stream_->SetSize(kUnsignedZero);
+  DCHECK(SUCCEEDED(hr));
+}
+
+bool UrlmonUrlRequest::Cache::Read(IStream* dest, size_t size,
+                                   size_t* bytes_copied) {
+  if (!dest || !size) {
+    NOTREACHED();
+    return false;
+  }
+
+  // Copy the data and clear cache if there is no more data to copy.
+  ULARGE_INTEGER size_to_copy = {size, 0};
+  ULARGE_INTEGER size_written = {0};
+  stream_->CopyTo(dest, size_to_copy, NULL, &size_written);
+
+  if (size_written.LowPart && bytes_copied)
+    *bytes_copied = size_written.LowPart;
+
+  if (!SizeRemaining()) {
+    Clear();
+    stream_->Seek(kZero, STREAM_SEEK_SET, NULL);
+  }
+
+  return (size_written.LowPart != 0);
+}
+
+bool UrlmonUrlRequest::Cache::Append(IStream* source,
+                                     size_t* bytes_copied) {
+  if (!source) {
+    NOTREACHED();
+    return false;
+  }
+
+  size_t current_pos = CurrentPos();
+  stream_->Seek(kZero, STREAM_SEEK_END, NULL);
+
+  HRESULT hr = S_OK;
+  while (SUCCEEDED(hr)) {
+    DWORD chunk_read = 0;  // NOLINT
+    hr = source->Read(read_buffer_, sizeof(read_buffer_), &chunk_read);
+    if (!chunk_read)
+      break;
+
+    DWORD chunk_written = 0;  // NOLINT
+    stream_->Write(read_buffer_, chunk_read, &chunk_written);
+    DCHECK_EQ(chunk_read, chunk_written);
+
+    if (bytes_copied)
+      *bytes_copied += chunk_written;
+  }
+
+  LARGE_INTEGER last_read_position = {current_pos, 0};
+  stream_->Seek(last_read_position, STREAM_SEEK_SET, NULL);
+  return SUCCEEDED(hr);
+}
+
+bool UrlmonUrlRequest::Cache::Create() {
+  DCHECK(stream_ == NULL);
+  bool ret = SUCCEEDED(CreateStreamOnHGlobal(NULL, TRUE, stream_.Receive()));
+  DCHECK(ret && stream_);
+  return ret;
+}
+
+net::Error UrlmonUrlRequest::HresultToNetError(HRESULT hr) {
+  // Useful reference:
+  // http://msdn.microsoft.com/en-us/library/ms775145(VS.85).aspx
+
+  net::Error ret = net::ERR_UNEXPECTED;
+
+  switch (hr) {
+    case S_OK:
+      ret = net::OK;
+      break;
+
+    case MK_E_SYNTAX:
+      ret = net::ERR_INVALID_URL;
+      break;
+
+    case INET_E_CANNOT_CONNECT:
+      ret = net::ERR_CONNECTION_FAILED;
+      break;
+
+    case INET_E_DOWNLOAD_FAILURE:
+    case INET_E_CONNECTION_TIMEOUT:
+    case E_ABORT:
+      ret = net::ERR_CONNECTION_ABORTED;
+      break;
+
+    case INET_E_DATA_NOT_AVAILABLE:
+      ret = net::ERR_EMPTY_RESPONSE;
+      break;
+
+    case INET_E_RESOURCE_NOT_FOUND:
+      // To behave more closely to the chrome network stack, we translate this
+      // error value as tunnel connection failed.  This error value is tested
+      // in the ProxyTunnelRedirectTest and UnexpectedServerAuthTest tests.
+      ret = net::ERR_TUNNEL_CONNECTION_FAILED;
+      break;
+
+    case INET_E_INVALID_URL:
+    case INET_E_UNKNOWN_PROTOCOL:
+    case INET_E_REDIRECT_FAILED:
+      ret = net::ERR_INVALID_URL;
+      break;
+
+    case INET_E_INVALID_CERTIFICATE:
+      ret = net::ERR_CERT_INVALID;
+      break;
+
+    case E_ACCESSDENIED:
+      ret = net::ERR_ACCESS_DENIED;
+      break;
+
+    default:
+      DLOG(WARNING)
+          << StringPrintf("TODO: translate HRESULT 0x%08X to net::Error", hr);
+      break;
+  }
+  return ret;
+}