/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsPACMan.h"

#include "mozilla/Preferences.h"
#include "nsContentUtils.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsIAuthPrompt.h"
#include "nsIDHCPClient.h"
#include "nsIHttpChannel.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch.h"
#include "nsIPromptFactory.h"
#include "nsIProtocolProxyService.h"
#include "nsISystemProxySettings.h"
#include "nsNetUtil.h"
#include "nsThreadUtils.h"
#include "mozilla/Result.h"
#include "mozilla/ResultExtensions.h"

//-----------------------------------------------------------------------------

namespace mozilla {
namespace net {

LazyLogModule gProxyLog("proxy");

#undef LOG
#define LOG(args) MOZ_LOG(gProxyLog, LogLevel::Debug, args)
#define MOZ_WPAD_URL "http://wpad/wpad.dat"
#define MOZ_DHCP_WPAD_OPTION 252

// The PAC thread does evaluations of both PAC files and
// nsISystemProxySettings because they can both block the calling thread and we
// don't want that on the main thread

// Check to see if the underlying request was not an error page in the case of
// a HTTP request.  For other types of channels, just return true.
static bool HttpRequestSucceeded(nsIStreamLoader *loader) {
  nsCOMPtr<nsIRequest> request;
  loader->GetRequest(getter_AddRefs(request));

  bool result = true;  // default to assuming success

  nsCOMPtr<nsIHttpChannel> httpChannel = do_QueryInterface(request);
  if (httpChannel) {
    // failsafe
    Unused << httpChannel->GetRequestSucceeded(&result);
  }

  return result;
}

// Read preference setting of extra JavaScript context heap size.
// PrefService tends to be run on main thread, where ProxyAutoConfig runs on
// ProxyResolution thread, so it's read here and passed to ProxyAutoConfig.
static uint32_t GetExtraJSContextHeapSize() {
  MOZ_ASSERT(NS_IsMainThread());

  static int32_t extraSize = -1;

  if (extraSize < 0) {
    nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
    int32_t value;

    if (prefs &&
        NS_SUCCEEDED(prefs->GetIntPref(
            "network.proxy.autoconfig_extra_jscontext_heap_size", &value))) {
      LOG(("autoconfig_extra_jscontext_heap_size: %d\n", value));

      extraSize = value;
    }
  }

  return extraSize < 0 ? 0 : extraSize;
}

// Read network proxy type from preference
// Used to verify that the preference is WPAD in nsPACMan::ConfigureWPAD
nsresult GetNetworkProxyTypeFromPref(int32_t *type) {
  *type = 0;
  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);

  if (!prefs) {
    LOG(("Failed to get a preference service object"));
    return NS_ERROR_FACTORY_NOT_REGISTERED;
  }
  nsresult rv = prefs->GetIntPref("network.proxy.type", type);
  if (NS_FAILED(rv)) {
    LOG(("Failed to retrieve network.proxy.type from prefs"));
    return rv;
  }
  LOG(("network.proxy.type pref retrieved: %d\n", *type));
  return NS_OK;
}

//-----------------------------------------------------------------------------

// The ExecuteCallback runnable is triggered by
// nsPACManCallback::OnQueryComplete on the Main thread when its completion is
// discovered on the pac thread

class ExecuteCallback final : public Runnable {
 public:
  ExecuteCallback(nsPACManCallback *aCallback, nsresult status)
      : Runnable("net::ExecuteCallback"),
        mCallback(aCallback),
        mStatus(status) {}

  void SetPACString(const nsACString &pacString) { mPACString = pacString; }

  void SetPACURL(const nsACString &pacURL) { mPACURL = pacURL; }

  NS_IMETHOD Run() override {
    mCallback->OnQueryComplete(mStatus, mPACString, mPACURL);
    mCallback = nullptr;
    return NS_OK;
  }

 private:
  RefPtr<nsPACManCallback> mCallback;
  nsresult mStatus;
  nsCString mPACString;
  nsCString mPACURL;
};

//-----------------------------------------------------------------------------

// The PAC thread must be deleted from the main thread, this class
// acts as a proxy to do that, as the PACMan is reference counted
// and might be destroyed on either thread

class ShutdownThread final : public Runnable {
 public:
  explicit ShutdownThread(nsIThread *thread)
      : Runnable("net::ShutdownThread"), mThread(thread) {}

  NS_IMETHOD Run() override {
    MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
    mThread->Shutdown();
    return NS_OK;
  }

 private:
  nsCOMPtr<nsIThread> mThread;
};

// Dispatch this to wait until the PAC thread shuts down.

class WaitForThreadShutdown final : public Runnable {
 public:
  explicit WaitForThreadShutdown(nsPACMan *aPACMan)
      : Runnable("net::WaitForThreadShutdown"), mPACMan(aPACMan) {}

  NS_IMETHOD Run() override {
    MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
    if (mPACMan->mPACThread) {
      mPACMan->mPACThread->Shutdown();
      mPACMan->mPACThread = nullptr;
    }
    return NS_OK;
  }

 private:
  RefPtr<nsPACMan> mPACMan;
};

//-----------------------------------------------------------------------------

// PACLoadComplete allows the PAC thread to tell the main thread that
// the javascript PAC file has been installed (perhaps unsuccessfully)
// and that there is no reason to queue executions anymore

class PACLoadComplete final : public Runnable {
 public:
  explicit PACLoadComplete(nsPACMan *aPACMan)
      : Runnable("net::PACLoadComplete"), mPACMan(aPACMan) {}

  NS_IMETHOD Run() override {
    MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
    mPACMan->mLoader = nullptr;
    mPACMan->PostProcessPendingQ();
    return NS_OK;
  }

 private:
  RefPtr<nsPACMan> mPACMan;
};

//-----------------------------------------------------------------------------

// ConfigureWPADComplete allows the PAC thread to tell the main thread that
// the URL for the PAC file has been found
class ConfigureWPADComplete final : public Runnable {
 public:
  ConfigureWPADComplete(nsPACMan *aPACMan, const nsACString &aPACURISpec)
      : Runnable("net::ConfigureWPADComplete"),
        mPACMan(aPACMan),
        mPACURISpec(aPACURISpec) {}

  NS_IMETHOD Run() override {
    MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
    mPACMan->AssignPACURISpec(mPACURISpec);
    mPACMan->ContinueLoadingAfterPACUriKnown();
    return NS_OK;
  }

 private:
  RefPtr<nsPACMan> mPACMan;
  nsCString mPACURISpec;
};

//-----------------------------------------------------------------------------

// ExecutePACThreadAction is used to proxy actions from the main
// thread onto the PAC thread. There are 4 options: process the queue,
// cancel the queue, query DHCP for the PAC option
// and setup the javascript context with a new PAC file

class ExecutePACThreadAction final : public Runnable {
 public:
  // by default we just process the queue
  explicit ExecutePACThreadAction(nsPACMan *aPACMan)
      : Runnable("net::ExecutePACThreadAction"),
        mPACMan(aPACMan),
        mCancel(false),
        mCancelStatus(NS_OK),
        mSetupPAC(false),
        mExtraHeapSize(0),
        mConfigureWPAD(false),
        mShutdown(false) {}

  void CancelQueue(nsresult status, bool aShutdown) {
    mCancel = true;
    mCancelStatus = status;
    mShutdown = aShutdown;
  }

  void SetupPAC(const char *data, uint32_t dataLen, const nsACString &pacURI,
                uint32_t extraHeapSize) {
    mSetupPAC = true;
    mSetupPACData.Assign(data, dataLen);
    mSetupPACURI = pacURI;
    mExtraHeapSize = extraHeapSize;
  }

  void ConfigureWPAD() { mConfigureWPAD = true; }

  NS_IMETHOD Run() override {
    MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");
    if (mCancel) {
      mPACMan->CancelPendingQ(mCancelStatus, mShutdown);
      mCancel = false;
      return NS_OK;
    }

    if (mSetupPAC) {
      mSetupPAC = false;

      nsCOMPtr<nsIEventTarget> target = mPACMan->GetNeckoTarget();
      mPACMan->mPAC.Init(mSetupPACURI, mSetupPACData, mPACMan->mIncludePath,
                         mExtraHeapSize, target);

      RefPtr<PACLoadComplete> runnable = new PACLoadComplete(mPACMan);
      mPACMan->Dispatch(runnable.forget());
      return NS_OK;
    }

    if (mConfigureWPAD) {
      nsAutoCString spec;
      mConfigureWPAD = false;
      mPACMan->ConfigureWPAD(spec);
      RefPtr<ConfigureWPADComplete> runnable =
          new ConfigureWPADComplete(mPACMan, spec);
      mPACMan->Dispatch(runnable.forget());
      return NS_OK;
    }

    mPACMan->ProcessPendingQ();
    return NS_OK;
  }

 private:
  RefPtr<nsPACMan> mPACMan;

  bool mCancel;
  nsresult mCancelStatus;

  bool mSetupPAC;
  uint32_t mExtraHeapSize;
  nsCString mSetupPACData;
  nsCString mSetupPACURI;
  bool mConfigureWPAD;
  bool mShutdown;
};

//-----------------------------------------------------------------------------

PendingPACQuery::PendingPACQuery(nsPACMan *pacMan, nsIURI *uri,
                                 nsPACManCallback *callback,
                                 bool mainThreadResponse)
    : Runnable("net::PendingPACQuery"),
      mPort(0),
      mPACMan(pacMan),
      mCallback(callback),
      mOnMainThreadOnly(mainThreadResponse) {
  uri->GetAsciiSpec(mSpec);
  uri->GetAsciiHost(mHost);
  uri->GetScheme(mScheme);
  uri->GetPort(&mPort);
}

void PendingPACQuery::Complete(nsresult status, const nsACString &pacString) {
  if (!mCallback) return;
  RefPtr<ExecuteCallback> runnable = new ExecuteCallback(mCallback, status);
  runnable->SetPACString(pacString);
  if (mOnMainThreadOnly)
    mPACMan->Dispatch(runnable.forget());
  else
    runnable->Run();
}

void PendingPACQuery::UseAlternatePACFile(const nsACString &pacURL) {
  if (!mCallback) return;

  RefPtr<ExecuteCallback> runnable = new ExecuteCallback(mCallback, NS_OK);
  runnable->SetPACURL(pacURL);
  if (mOnMainThreadOnly)
    mPACMan->Dispatch(runnable.forget());
  else
    runnable->Run();
}

NS_IMETHODIMP
PendingPACQuery::Run() {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");
  mPACMan->PostQuery(this);
  return NS_OK;
}

//-----------------------------------------------------------------------------

static bool sThreadLocalSetup = false;
static uint32_t sThreadLocalIndex = 0xdeadbeef;  // out of range

static const char *kPACIncludePath =
    "network.proxy.autoconfig_url.include_path";

nsPACMan::nsPACMan(nsIEventTarget *mainThreadEventTarget)
    : NeckoTargetHolder(mainThreadEventTarget),
      mLoadPending(false),
      mShutdown(false),
      mLoadFailureCount(0),
      mInProgress(false),
      mAutoDetect(false),
      mWPADOverDHCPEnabled(false),
      mProxyConfigType(0) {
  MOZ_ASSERT(NS_IsMainThread(), "pacman must be created on main thread");
  if (!sThreadLocalSetup) {
    sThreadLocalSetup = true;
    PR_NewThreadPrivateIndex(&sThreadLocalIndex, nullptr);
  }
  mPAC.SetThreadLocalIndex(sThreadLocalIndex);
  mIncludePath = Preferences::GetBool(kPACIncludePath, false);
}

nsPACMan::~nsPACMan() {
  MOZ_ASSERT(mShutdown, "Shutdown must be called before dtor.");

  if (mPACThread) {
    if (NS_IsMainThread()) {
      mPACThread->Shutdown();
      mPACThread = nullptr;
    } else {
      RefPtr<ShutdownThread> runnable = new ShutdownThread(mPACThread);
      Dispatch(runnable.forget());
    }
  }

  NS_ASSERTION(mLoader == nullptr, "pac man not shutdown properly");
  NS_ASSERTION(mPendingQ.isEmpty(), "pac man not shutdown properly");
}

void nsPACMan::Shutdown() {
  MOZ_ASSERT(NS_IsMainThread(), "pacman must be shutdown on main thread");
  if (mShutdown) {
    return;
  }

  CancelExistingLoad();

  if (mPACThread) {
    PostCancelPendingQ(NS_ERROR_ABORT, /*aShutdown =*/true);

    // Shutdown is initiated from an observer. We don't want to block the
    // observer service on thread shutdown so we post a shutdown runnable that
    // will run after we return instead.
    RefPtr<WaitForThreadShutdown> runnable = new WaitForThreadShutdown(this);
    Dispatch(runnable.forget());
  }

  mShutdown = true;
}

nsresult nsPACMan::DispatchToPAC(already_AddRefed<nsIRunnable> aEvent,
                                 bool aSync) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");

  nsCOMPtr<nsIRunnable> e(aEvent);

  if (mShutdown) {
    return NS_ERROR_NOT_AVAILABLE;
  }

  // Lazily create the PAC thread. This method is main-thread only so we don't
  // have to worry about threading issues here.
  if (!mPACThread) {
    MOZ_TRY(NS_NewNamedThread("ProxyResolution", getter_AddRefs(mPACThread)));
  }

  return mPACThread->Dispatch(
      e.forget(),
      aSync ? nsIEventTarget::DISPATCH_SYNC : nsIEventTarget::DISPATCH_NORMAL);
}

nsresult nsPACMan::AsyncGetProxyForURI(nsIURI *uri, nsPACManCallback *callback,
                                       bool mainThreadResponse) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  if (mShutdown) return NS_ERROR_NOT_AVAILABLE;

  // Maybe Reload PAC
  if (!mPACURISpec.IsEmpty() && !mScheduledReload.IsNull() &&
      TimeStamp::Now() > mScheduledReload) {
    LOG(("nsPACMan::AsyncGetProxyForURI reload as scheduled\n"));

    LoadPACFromURI(mAutoDetect ? EmptyCString() : mPACURISpec, false);
  }

  RefPtr<PendingPACQuery> query =
      new PendingPACQuery(this, uri, callback, mainThreadResponse);

  if (IsPACURI(uri)) {
    // deal with this directly instead of queueing it
    query->Complete(NS_OK, EmptyCString());
    return NS_OK;
  }

  return DispatchToPAC(query.forget());
}

nsresult nsPACMan::PostQuery(PendingPACQuery *query) {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");

  if (mShutdown) {
    query->Complete(NS_ERROR_NOT_AVAILABLE, EmptyCString());
    return NS_OK;
  }

  // add a reference to the query while it is in the pending list
  RefPtr<PendingPACQuery> addref(query);
  mPendingQ.insertBack(addref.forget().take());
  ProcessPendingQ();
  return NS_OK;
}

nsresult nsPACMan::LoadPACFromURI(const nsACString &aSpec) {
  return LoadPACFromURI(aSpec, true);
}

nsresult nsPACMan::LoadPACFromURI(const nsACString &aSpec,
                                  bool aResetLoadFailureCount) {
  NS_ENSURE_STATE(!mShutdown);

  nsCOMPtr<nsIStreamLoader> loader =
      do_CreateInstance(NS_STREAMLOADER_CONTRACTID);
  NS_ENSURE_STATE(loader);

  LOG(("nsPACMan::LoadPACFromURI aSpec: %s, aResetLoadFailureCount: %s\n",
       aSpec.BeginReading(), aResetLoadFailureCount ? "true" : "false"));

  CancelExistingLoad();

  mLoader = loader;
  mPACURIRedirectSpec.Truncate();
  mNormalPACURISpec.Truncate();  // set at load time
  if (aResetLoadFailureCount) {
    mLoadFailureCount = 0;
  }
  mAutoDetect = aSpec.IsEmpty();
  mPACURISpec.Assign(aSpec);

  // reset to Null
  mScheduledReload = TimeStamp();

  // if we're on the main thread here so we can get hold of prefs,
  // we check that we have WPAD preffed on if we're auto-detecting
  if (mAutoDetect && NS_IsMainThread()) {
    nsresult rv = GetNetworkProxyTypeFromPref(&mProxyConfigType);
    if (NS_FAILED(rv)) {
      return rv;
    }
    if (mProxyConfigType != nsIProtocolProxyService::PROXYCONFIG_WPAD) {
      LOG(
          ("LoadPACFromURI - Aborting WPAD autodetection because the pref "
           "doesn't match anymore"));
      return NS_BINDING_ABORTED;
    }
  }
  // Since we might get called from nsProtocolProxyService::Init, we need to
  // post an event back to the main thread before we try to use the IO service.
  //
  // But, we need to flag ourselves as loading, so that we queue up any PAC
  // queries the enter between now and when we actually load the PAC file.

  if (!mLoadPending) {
    nsCOMPtr<nsIRunnable> runnable = NewRunnableMethod(
        "nsPACMan::StartLoading", this, &nsPACMan::StartLoading);
    nsresult rv =
        NS_IsMainThread()
            ? Dispatch(runnable.forget())
            : GetCurrentThreadEventTarget()->Dispatch(runnable.forget());
    if (NS_FAILED(rv)) return rv;
    mLoadPending = true;
  }

  return NS_OK;
}

nsresult nsPACMan::GetPACFromDHCP(nsACString &aSpec) {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");
  if (!mDHCPClient) {
    LOG(
        ("nsPACMan::GetPACFromDHCP DHCP option %d query failed because there "
         "is no DHCP client available\n",
         MOZ_DHCP_WPAD_OPTION));
    return NS_ERROR_NOT_IMPLEMENTED;
  }
  nsresult rv;
  rv = mDHCPClient->GetOption(MOZ_DHCP_WPAD_OPTION, aSpec);
  if (NS_FAILED(rv)) {
    LOG((
        "nsPACMan::GetPACFromDHCP DHCP option %d query failed with result %d\n",
        MOZ_DHCP_WPAD_OPTION, (uint32_t)rv));
  } else {
    LOG(
        ("nsPACMan::GetPACFromDHCP DHCP option %d query succeeded, finding PAC "
         "URL %s\n",
         MOZ_DHCP_WPAD_OPTION, aSpec.BeginReading()));
  }
  return rv;
}

nsresult nsPACMan::ConfigureWPAD(nsACString &aSpec) {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");

  if (mProxyConfigType != nsIProtocolProxyService::PROXYCONFIG_WPAD) {
    LOG(
        ("ConfigureWPAD - Aborting WPAD autodetection because the pref "
         "doesn't match anymore"));
    return NS_BINDING_ABORTED;
  }

  aSpec.Truncate();
  if (mWPADOverDHCPEnabled) {
    GetPACFromDHCP(aSpec);
  }

  if (aSpec.IsEmpty()) {
    // We diverge from the WPAD spec here in that we don't walk the
    // hosts's FQDN, stripping components until we hit a TLD.  Doing so
    // is dangerous in the face of an incomplete list of TLDs, and TLDs
    // get added over time.  We could consider doing only a single
    // substitution of the first component, if that proves to help
    // compatibility.
    aSpec.AssignLiteral(MOZ_WPAD_URL);
  }
  return NS_OK;
}

void nsPACMan::AssignPACURISpec(const nsACString &aSpec) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  mPACURISpec.Assign(aSpec);
}

void nsPACMan::StartLoading() {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  mLoadPending = false;

  // CancelExistingLoad was called...
  if (!mLoader) {
    PostCancelPendingQ(NS_ERROR_ABORT);
    return;
  }

  if (mAutoDetect) {
    nsresult rv = GetNetworkProxyTypeFromPref(&mProxyConfigType);
    if (NS_FAILED(rv)) {
      NS_WARNING(
          "Could not retrieve Network Proxy Type pref when auto-detecting "
          "proxy. Halting.");
      return;
    }
    RefPtr<ExecutePACThreadAction> wpadConfigurer =
        new ExecutePACThreadAction(this);
    wpadConfigurer->ConfigureWPAD();
    DispatchToPAC(wpadConfigurer.forget());
  } else {
    ContinueLoadingAfterPACUriKnown();
  }
}

void nsPACMan::ContinueLoadingAfterPACUriKnown() {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");

  // CancelExistingLoad was called...
  if (!mLoader) {
    PostCancelPendingQ(NS_ERROR_ABORT);
    return;
  }
  if (NS_SUCCEEDED(mLoader->Init(this, nullptr))) {
    // Always hit the origin server when loading PAC.
    nsCOMPtr<nsIIOService> ios = do_GetIOService();
    if (ios) {
      nsCOMPtr<nsIChannel> channel;
      nsCOMPtr<nsIURI> pacURI;
      NS_NewURI(getter_AddRefs(pacURI), mPACURISpec);

      // NOTE: This results in GetProxyForURI being called
      if (pacURI) {
        nsresult rv = pacURI->GetSpec(mNormalPACURISpec);
        MOZ_RELEASE_ASSERT(NS_SUCCEEDED(rv));
        NS_NewChannel(getter_AddRefs(channel), pacURI,
                      nsContentUtils::GetSystemPrincipal(),
                      nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL,
                      nsIContentPolicy::TYPE_OTHER,
                      nullptr,  // PerformanceStorage,
                      nullptr,  // aLoadGroup
                      nullptr,  // aCallbacks
                      nsIRequest::LOAD_NORMAL, ios);
      } else {
        LOG(("nsPACMan::StartLoading Failed pacspec uri conversion %s\n",
             mPACURISpec.get()));
      }

      if (channel) {
        channel->SetLoadFlags(nsIRequest::LOAD_BYPASS_CACHE);
        channel->SetNotificationCallbacks(this);
        if (NS_SUCCEEDED(channel->AsyncOpen(mLoader))) return;
      }
    }
  }

  CancelExistingLoad();
  PostCancelPendingQ(NS_ERROR_UNEXPECTED);
}

void nsPACMan::OnLoadFailure() {
  int32_t minInterval = 5;    // 5 seconds
  int32_t maxInterval = 300;  // 5 minutes

  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
  if (prefs) {
    prefs->GetIntPref("network.proxy.autoconfig_retry_interval_min",
                      &minInterval);
    prefs->GetIntPref("network.proxy.autoconfig_retry_interval_max",
                      &maxInterval);
  }

  int32_t interval = minInterval << mLoadFailureCount++;  // seconds
  if (!interval || interval > maxInterval) interval = maxInterval;

  mScheduledReload = TimeStamp::Now() + TimeDuration::FromSeconds(interval);

  LOG(("OnLoadFailure: retry in %d seconds (%d fails)\n", interval,
       mLoadFailureCount));

  // while we wait for the retry queued members should try direct
  // even if that means fast failure.
  PostCancelPendingQ(NS_ERROR_NOT_AVAILABLE);
}

void nsPACMan::CancelExistingLoad() {
  if (mLoader) {
    nsCOMPtr<nsIRequest> request;
    mLoader->GetRequest(getter_AddRefs(request));
    if (request) request->Cancel(NS_ERROR_ABORT);
    mLoader = nullptr;
  }
}

void nsPACMan::PostProcessPendingQ() {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  RefPtr<ExecutePACThreadAction> pending = new ExecutePACThreadAction(this);
  DispatchToPAC(pending.forget());
}

void nsPACMan::PostCancelPendingQ(nsresult status, bool aShutdown) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  RefPtr<ExecutePACThreadAction> pending = new ExecutePACThreadAction(this);
  pending->CancelQueue(status, aShutdown);
  DispatchToPAC(pending.forget());
}

void nsPACMan::CancelPendingQ(nsresult status, bool aShutdown) {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");
  RefPtr<PendingPACQuery> query;

  while (!mPendingQ.isEmpty()) {
    query = dont_AddRef(mPendingQ.popLast());
    query->Complete(status, EmptyCString());
  }

  if (aShutdown) mPAC.Shutdown();
}

void nsPACMan::ProcessPendingQ() {
  MOZ_ASSERT(!NS_IsMainThread(), "wrong thread");
  while (ProcessPending())
    ;

  if (mShutdown) {
    mPAC.Shutdown();
  } else {
    // do GC while the thread has nothing pending
    mPAC.GC();
  }
}

// returns true if progress was made by shortening the queue
bool nsPACMan::ProcessPending() {
  if (mPendingQ.isEmpty()) return false;

  // queue during normal load, but if we are retrying a failed load then
  // fast fail the queries
  if (mInProgress || (IsLoading() && !mLoadFailureCount)) return false;

  RefPtr<PendingPACQuery> query(dont_AddRef(mPendingQ.popFirst()));

  if (mShutdown || IsLoading()) {
    query->Complete(NS_ERROR_NOT_AVAILABLE, EmptyCString());
    return true;
  }

  nsAutoCString pacString;
  bool completed = false;
  mInProgress = true;
  nsAutoCString PACURI;

  // first we need to consider the system proxy changing the pac url
  if (mSystemProxySettings &&
      NS_SUCCEEDED(mSystemProxySettings->GetPACURI(PACURI)) &&
      !PACURI.IsEmpty() && !PACURI.Equals(mPACURISpec)) {
    query->UseAlternatePACFile(PACURI);
    LOG(("Use PAC from system settings: %s\n", PACURI.get()));
    completed = true;
  }

  // now try the system proxy settings for this particular url if
  // PAC was not specified
  if (!completed && mSystemProxySettings && PACURI.IsEmpty() &&
      NS_SUCCEEDED(mSystemProxySettings->GetProxyForURI(
          query->mSpec, query->mScheme, query->mHost, query->mPort,
          pacString))) {
    LOG(("Use proxy from system settings: %s\n", pacString.get()));
    query->Complete(NS_OK, pacString);
    completed = true;
  }

  // the systemproxysettings didn't complete the resolution. try via PAC
  if (!completed) {
    nsresult status =
        mPAC.GetProxyForURI(query->mSpec, query->mHost, pacString);
    LOG(("Use proxy from PAC: %s\n", pacString.get()));
    query->Complete(status, pacString);
  }

  mInProgress = false;
  return true;
}

NS_IMPL_ISUPPORTS(nsPACMan, nsIStreamLoaderObserver, nsIInterfaceRequestor,
                  nsIChannelEventSink)

NS_IMETHODIMP
nsPACMan::OnStreamComplete(nsIStreamLoader *loader, nsISupports *context,
                           nsresult status, uint32_t dataLen,
                           const uint8_t *data) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");
  if (mLoader != loader) {
    // If this happens, then it means that LoadPACFromURI was called more
    // than once before the initial call completed.  In this case, status
    // should be NS_ERROR_ABORT, and if so, then we know that we can and
    // should delay any processing.
    LOG(("OnStreamComplete: called more than once\n"));
    if (status == NS_ERROR_ABORT) return NS_OK;
  }

  LOG(("OnStreamComplete: entry\n"));

  if (NS_SUCCEEDED(status) && HttpRequestSucceeded(loader)) {
    // Get the URI spec used to load this PAC script.
    nsAutoCString pacURI;
    {
      nsCOMPtr<nsIRequest> request;
      loader->GetRequest(getter_AddRefs(request));
      nsCOMPtr<nsIChannel> channel = do_QueryInterface(request);
      if (channel) {
        nsCOMPtr<nsIURI> uri;
        channel->GetURI(getter_AddRefs(uri));
        if (uri) uri->GetAsciiSpec(pacURI);
      }
    }

    // We succeeded in loading the pac file using a bunch of interfaces that are
    // main thread only.  Unfortunately, we have to initialize the instance of
    // the PAC evaluator (NS_PROXYAUTOCONFIG_CONTRACTID) on the PAC thread,
    // because that's where it will be used.
    RefPtr<ExecutePACThreadAction> pending = new ExecutePACThreadAction(this);
    pending->SetupPAC(reinterpret_cast<const char *>(data), dataLen, pacURI,
                      GetExtraJSContextHeapSize());
    DispatchToPAC(pending.forget());

    LOG(("OnStreamComplete: process the PAC contents\n"));

    // Even if the PAC file could not be parsed, we did succeed in loading the
    // data for it.
    mLoadFailureCount = 0;
  } else {
    // We were unable to load the PAC file (presumably because of a network
    // failure).  Try again a little later.
    LOG(("OnStreamComplete: unable to load PAC, retry later\n"));
    OnLoadFailure();
  }

  if (NS_SUCCEEDED(status))
    PostProcessPendingQ();
  else
    PostCancelPendingQ(status);

  return NS_OK;
}

NS_IMETHODIMP
nsPACMan::GetInterface(const nsIID &iid, void **result) {
  // In case loading the PAC file requires authentication.
  if (iid.Equals(NS_GET_IID(nsIAuthPrompt))) {
    nsCOMPtr<nsIPromptFactory> promptFac =
        do_GetService("@mozilla.org/prompter;1");
    NS_ENSURE_TRUE(promptFac, NS_ERROR_FAILURE);
    return promptFac->GetPrompt(nullptr, iid,
                                reinterpret_cast<void **>(result));
  }

  // In case loading the PAC file results in a redirect.
  if (iid.Equals(NS_GET_IID(nsIChannelEventSink))) {
    NS_ADDREF_THIS();
    *result = static_cast<nsIChannelEventSink *>(this);
    return NS_OK;
  }

  return NS_ERROR_NO_INTERFACE;
}

NS_IMETHODIMP
nsPACMan::AsyncOnChannelRedirect(nsIChannel *oldChannel, nsIChannel *newChannel,
                                 uint32_t flags,
                                 nsIAsyncVerifyRedirectCallback *callback) {
  MOZ_ASSERT(NS_IsMainThread(), "wrong thread");

  nsresult rv = NS_OK;
  nsCOMPtr<nsIURI> pacURI;
  if (NS_FAILED((rv = newChannel->GetURI(getter_AddRefs(pacURI))))) return rv;

  rv = pacURI->GetSpec(mPACURIRedirectSpec);
  if (NS_FAILED(rv)) return rv;

  LOG(("nsPACMan redirect from original %s to redirected %s\n",
       mPACURISpec.get(), mPACURIRedirectSpec.get()));

  // do not update mPACURISpec - that needs to stay as the
  // configured URI so that we can determine when the config changes.
  // However do track the most recent URI in the redirect change
  // as mPACURIRedirectSpec so that URI can be allowed to bypass
  // the proxy and actually fetch the pac file.

  callback->OnRedirectVerifyCallback(NS_OK);
  return NS_OK;
}

nsresult nsPACMan::Init(nsISystemProxySettings *systemProxySettings) {
  mSystemProxySettings = systemProxySettings;
  mDHCPClient = do_GetService(NS_DHCPCLIENT_CONTRACTID);
  return NS_OK;
}

}  // namespace net
}  // namespace mozilla