/* -*- 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 "nsThreadUtils.h"
#include "nsIAuthPrompt.h"
#include "nsIPromptFactory.h"
#include "nsIHttpChannel.h"
#include "nsIPrefService.h"
#include "nsIPrefBranch.h"
#include "nsNetUtil.h"
#include "nsCRT.h"
#include "prmon.h"
#include "nsIAsyncVerifyRedirectCallback.h"
#include "nsProxyRelease.h"

//-----------------------------------------------------------------------------
using namespace mozilla;
using namespace mozilla::net;

#include "prlog.h"
#if defined(PR_LOGGING)
static PRLogModuleInfo *
GetProxyLog()
{
    static PRLogModuleInfo *sLog;
    if (!sLog)
        sLog = PR_NewLogModule("proxy");
    return sLog;
}
#endif
#define LOG(args) PR_LOG(GetProxyLog(), PR_LOG_DEBUG, args)

// 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)
    httpChannel->GetRequestSucceeded(&result);

  return result;
}

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

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

class ExecuteCallback MOZ_FINAL : public nsRunnable
{
public:
  ExecuteCallback(nsPACManCallback *aCallback,
                  nsresult status)
    : mCallback(aCallback)
    , mStatus(status)
  {
  }

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

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

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

private:
  nsRefPtr<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 MOZ_FINAL : public nsRunnable
{
public:
  ShutdownThread(nsIThread *thread)
    : mThread(thread)
  {
  }

  NS_IMETHODIMP Run()
  {
    NS_ABORT_IF_FALSE(NS_IsMainThread(), "wrong thread");
    mThread->Shutdown();
    return NS_OK;
  }

private:
  nsCOMPtr<nsIThread> mThread;
};

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

// 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 MOZ_FINAL : public nsRunnable
{
public:
  PACLoadComplete(nsPACMan *aPACMan)
    : mPACMan(aPACMan)
  {
  }

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

private:
    nsRefPtr<nsPACMan> mPACMan;
};

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

// ExecutePACThreadAction is used to proxy actions from the main
// thread onto the PAC thread. There are 3 options: process the queue,
// cancel the queue, and setup the javascript context with a new PAC file

class ExecutePACThreadAction MOZ_FINAL : public nsRunnable
{
public:
  // by default we just process the queue
  ExecutePACThreadAction(nsPACMan *aPACMan)
    : mPACMan(aPACMan)
    , mCancel(false)
    , mSetupPAC(false)
  { }

  void CancelQueue (nsresult status)
  {
    mCancel = true;
    mCancelStatus = status;
  }

  void SetupPAC (const char *text, uint32_t datalen, nsCString &pacURI)
  {
    mSetupPAC = true;
    mSetupPACData.Assign(text, datalen);
    mSetupPACURI = pacURI;
  }

  NS_IMETHODIMP Run()
  {
    NS_ABORT_IF_FALSE(!NS_IsMainThread(), "wrong thread");
    if (mCancel) {
      mPACMan->CancelPendingQ(mCancelStatus);
      mCancel = false;
      return NS_OK;
    }

    if (mSetupPAC) {
      mSetupPAC = false;

      mPACMan->mPAC.Init(mSetupPACURI,
                         mSetupPACData);

      nsRefPtr<PACLoadComplete> runnable = new PACLoadComplete(mPACMan);
      NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL);
      return NS_OK;
    }

    mPACMan->ProcessPendingQ();
    return NS_OK;
  }

private:
  nsRefPtr<nsPACMan> mPACMan;

  bool      mCancel;
  nsresult  mCancelStatus;

  bool                 mSetupPAC;
  nsCString            mSetupPACData;
  nsCString            mSetupPACURI;
};

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

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

void
PendingPACQuery::Complete(nsresult status, const nsCString &pacString)
{
  if (!mCallback)
    return;
  nsRefPtr<ExecuteCallback> runnable = new ExecuteCallback(mCallback, status);
  runnable->SetPACString(pacString);
  if (mOnMainThreadOnly)
    NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL);
  else
    runnable->Run();
}

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

  nsRefPtr<ExecuteCallback> runnable = new ExecuteCallback(mCallback, NS_OK);
  runnable->SetPACURL(pacURL);
  if (mOnMainThreadOnly)
    NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL);
  else
    runnable->Run();
}

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

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

nsPACMan::nsPACMan()
  : mLoadPending(false)
  , mShutdown(false)
  , mLoadFailureCount(0)
  , mInProgress(false)
{
  NS_ABORT_IF_FALSE(NS_IsMainThread(), "pacman must be created on main thread");
}

nsPACMan::~nsPACMan()
{
  if (mPACThread) {
    if (NS_IsMainThread()) {
      mPACThread->Shutdown();
    }
    else {
      nsRefPtr<ShutdownThread> runnable = new ShutdownThread(mPACThread);
      NS_DispatchToMainThread(runnable, NS_DISPATCH_NORMAL);
    }
  }

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

void
nsPACMan::Shutdown()
{
  NS_ABORT_IF_FALSE(NS_IsMainThread(), "pacman must be shutdown on main thread");
  CancelExistingLoad();
  mShutdown = true;
  PostCancelPendingQ(NS_ERROR_ABORT);
}

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

  // Maybe Reload PAC
  if (!mPACURISpec.IsEmpty() && !mScheduledReload.IsNull() &&
      TimeStamp::Now() > mScheduledReload)
    LoadPACFromURI(EmptyCString());

  nsRefPtr<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 mPACThread->Dispatch(query, nsIEventTarget::DISPATCH_NORMAL);
}

nsresult
nsPACMan::PostQuery(PendingPACQuery *query)
{
  NS_ABORT_IF_FALSE(!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
  nsRefPtr<PendingPACQuery> addref(query);
  mPendingQ.insertBack(addref.forget().get());
  ProcessPendingQ();
  return NS_OK;
}

nsresult
nsPACMan::LoadPACFromURI(const nsCString &spec)
{
  NS_ENSURE_STATE(!mShutdown);
  NS_ENSURE_ARG(!spec.IsEmpty() || !mPACURISpec.IsEmpty());

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

  // 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> event =
      NS_NewRunnableMethod(this, &nsPACMan::StartLoading);
    nsresult rv;
    if (NS_FAILED(rv = NS_DispatchToCurrentThread(event)))
      return rv;
    mLoadPending = true;
  }

  CancelExistingLoad();

  mLoader = loader;
  if (!spec.IsEmpty()) {
    mPACURISpec = spec;
    mPACURIRedirectSpec.Truncate();
    mLoadFailureCount = 0;  // reset
  }

  // reset to Null
  mScheduledReload = TimeStamp();
  return NS_OK;
}

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

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

  if (NS_SUCCEEDED(mLoader->Init(this))) {
    // 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) {
        ios->NewChannelFromURI(pacURI, getter_AddRefs(channel));
      }
      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, nullptr)))
          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);

  // 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()
{
  NS_ABORT_IF_FALSE(NS_IsMainThread(), "wrong thread");
  nsRefPtr<ExecutePACThreadAction> pending =
    new ExecutePACThreadAction(this);
  if (mPACThread)
    mPACThread->Dispatch(pending, nsIEventTarget::DISPATCH_NORMAL);
}

void
nsPACMan::PostCancelPendingQ(nsresult status)
{
  NS_ABORT_IF_FALSE(NS_IsMainThread(), "wrong thread");
  nsRefPtr<ExecutePACThreadAction> pending =
    new ExecutePACThreadAction(this);
  pending->CancelQueue(status);
  if (mPACThread)
    mPACThread->Dispatch(pending, nsIEventTarget::DISPATCH_NORMAL);
}

void
nsPACMan::CancelPendingQ(nsresult status)
{
  NS_ABORT_IF_FALSE(!NS_IsMainThread(), "wrong thread");
  nsRefPtr<PendingPACQuery> query;

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

  if (mShutdown)
    mPAC.Shutdown();
}

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

  // do GC while the thread has nothing pending
  mPAC.GC();

  if (mShutdown)
    mPAC.Shutdown();
}

// 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;

  nsRefPtr<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);
    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))) {
    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);
    query->Complete(status, pacString);
  }

  mInProgress = false;
  return true;
}

NS_IMPL_THREADSAFE_ISUPPORTS3(nsPACMan, nsIStreamLoaderObserver,
                              nsIInterfaceRequestor, nsIChannelEventSink)

NS_IMETHODIMP
nsPACMan::OnStreamComplete(nsIStreamLoader *loader,
                           nsISupports *context,
                           nsresult status,
                           uint32_t dataLen,
                           const uint8_t *data)
{
  NS_ABORT_IF_FALSE(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.
    if (status == NS_ERROR_ABORT)
      return NS_OK;
  }

  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 assume that the PAC text is ASCII (or ISO-Latin-1).  We've had this
    // assumption forever, and some real-world PAC scripts actually have some
    // non-ASCII text in comment blocks (see bug 296163).
    const char *text = (const char *) data;

    // we have 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 is where it will be used.

    nsRefPtr<ExecutePACThreadAction> pending =
      new ExecutePACThreadAction(this);
    pending->SetupPAC(text, dataLen, pacURI);
    if (mPACThread)
      mPACThread->Dispatch(pending, nsIEventTarget::DISPATCH_NORMAL);

    // 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.
    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)
{
  NS_ABORT_IF_FALSE(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;
}

void
nsPACMan::NamePACThread()
{
  NS_ABORT_IF_FALSE(!NS_IsMainThread(), "wrong thread");
  PR_SetCurrentThreadName("Proxy Resolution");
}

nsresult
nsPACMan::Init(nsISystemProxySettings *systemProxySettings)
{
  mSystemProxySettings = systemProxySettings;

  nsresult rv = NS_NewThread(getter_AddRefs(mPACThread), nullptr);
  if (NS_FAILED(rv))
    return rv;

  nsCOMPtr<nsIRunnable> event = NS_NewRunnableMethod(this, &nsPACMan::NamePACThread);
  // don't check return value as it is not a big deal for this to fail.
  mPACThread->Dispatch(event, nsIEventTarget::DISPATCH_NORMAL);

  return NS_OK;
}
