/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */

// See also: docshell/base/nsAboutRedirector.cpp

#include "AboutRedirector.h"
#include "nsNetUtil.h"
#include "nsIAboutNewTabService.h"
#include "nsIChannel.h"
#include "nsIURI.h"
#include "nsIScriptSecurityManager.h"
#include "nsIProtocolHandler.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Preferences.h"
#include "nsServiceManagerUtils.h"

namespace mozilla {
namespace browser {

NS_IMPL_ISUPPORTS(AboutRedirector, nsIAboutModule)

bool AboutRedirector::sNewTabPageEnabled = false;
bool AboutRedirector::sNewCertErrorPageEnabled = false;

static const uint32_t ACTIVITY_STREAM_FLAGS =
  nsIAboutModule::ALLOW_SCRIPT |
  nsIAboutModule::ENABLE_INDEXED_DB |
  nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
  nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT;

struct RedirEntry {
  const char* id;
  const char* url;
  uint32_t flags;
};

/*
  Entries which do not have URI_SAFE_FOR_UNTRUSTED_CONTENT will run with chrome
  privileges. This is potentially dangerous. Please use
  URI_SAFE_FOR_UNTRUSTED_CONTENT in the third argument to each map item below
  unless your about: page really needs chrome privileges. Security review is
  required before adding new map entries without
  URI_SAFE_FOR_UNTRUSTED_CONTENT.
*/
static const RedirEntry kRedirMap[] = {
  { "blocked", "chrome://browser/content/blockedSite.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::URI_CAN_LOAD_IN_CHILD |
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "certerror", "chrome://browser/content/aboutNetError.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::URI_CAN_LOAD_IN_CHILD |
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "tabcrashed", "chrome://browser/content/aboutTabCrashed.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "feeds", "chrome://browser/content/feeds/subscribe.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "privatebrowsing", "chrome://browser/content/aboutPrivateBrowsing.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
    nsIAboutModule::ALLOW_SCRIPT },
  { "rights",
    "chrome://global/content/aboutRights.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::MAKE_LINKABLE |
    nsIAboutModule::ALLOW_SCRIPT },
  { "robots", "chrome://browser/content/aboutRobots.xhtml",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::ALLOW_SCRIPT },
  { "searchreset", "chrome://browser/content/search/searchReset.xhtml",
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "sessionrestore", "chrome://browser/content/aboutSessionRestore.xhtml",
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "welcomeback", "chrome://browser/content/aboutWelcomeBack.xhtml",
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  // Actual activity stream URL for home and newtab are set in channel creation
  { "home", "about:blank", ACTIVITY_STREAM_FLAGS },
  { "newtab", "about:blank", ACTIVITY_STREAM_FLAGS },
  { "welcome", "about:blank",
    nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::ALLOW_SCRIPT },
  { "library", "chrome://browser/content/aboutLibrary.xhtml",
    nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT },
  { "preferences", "chrome://browser/content/preferences/in-content/preferences.xul",
    nsIAboutModule::ALLOW_SCRIPT },
  { "downloads", "chrome://browser/content/downloads/contentAreaDownloadsView.xul",
    nsIAboutModule::ALLOW_SCRIPT },
  { "reader", "chrome://global/content/reader/aboutReader.html",
    nsIAboutModule::URI_SAFE_FOR_UNTRUSTED_CONTENT |
    nsIAboutModule::ALLOW_SCRIPT |
    nsIAboutModule::URI_MUST_LOAD_IN_CHILD |
    nsIAboutModule::HIDE_FROM_ABOUTABOUT },
  { "restartrequired", "chrome://browser/content/aboutRestartRequired.xhtml",
    nsIAboutModule::ALLOW_SCRIPT },
};

static nsAutoCString
GetAboutModuleName(nsIURI *aURI)
{
  nsAutoCString path;
  aURI->GetPathQueryRef(path);

  int32_t f = path.FindChar('#');
  if (f >= 0)
    path.SetLength(f);

  f = path.FindChar('?');
  if (f >= 0)
    path.SetLength(f);

  ToLowerCase(path);
  return path;
}

NS_IMETHODIMP
AboutRedirector::NewChannel(nsIURI* aURI,
                            nsILoadInfo* aLoadInfo,
                            nsIChannel** result)
{
  NS_ENSURE_ARG_POINTER(aURI);
  NS_ENSURE_ARG_POINTER(aLoadInfo);

  NS_ASSERTION(result, "must not be null");

  nsAutoCString path = GetAboutModuleName(aURI);

  nsresult rv;
  nsCOMPtr<nsIIOService> ioService = do_GetIOService(&rv);
  NS_ENSURE_SUCCESS(rv, rv);

  static bool sNTPEnabledCacheInited = false;
  if (!sNTPEnabledCacheInited) {
    Preferences::AddBoolVarCache(&AboutRedirector::sNewTabPageEnabled,
                                 "browser.newtabpage.enabled");
    sNTPEnabledCacheInited = true;
  }

  static bool sNCEPEnabledCacheInited = false;
  if (!sNCEPEnabledCacheInited) {
    Preferences::AddBoolVarCache(&AboutRedirector::sNewCertErrorPageEnabled,
                                 "browser.security.newcerterrorpage.enabled");
    sNCEPEnabledCacheInited = true;
  }

  for (auto & redir : kRedirMap) {
    if (!strcmp(path.get(), redir.id)) {
      nsAutoCString url;

      // Let the aboutNewTabService decide where to redirect for about:home and
      // enabled about:newtab. Disabledx about:newtab page uses fallback.
      if (path.EqualsLiteral("home") ||
          (sNewTabPageEnabled && path.EqualsLiteral("newtab")) ||
          path.EqualsLiteral("welcome")) {
        nsCOMPtr<nsIAboutNewTabService> aboutNewTabService =
          do_GetService("@mozilla.org/browser/aboutnewtab-service;1", &rv);
        NS_ENSURE_SUCCESS(rv, rv);
        rv = aboutNewTabService->GetDefaultURL(url);
        NS_ENSURE_SUCCESS(rv, rv);
      }

      if (sNewCertErrorPageEnabled && path.EqualsLiteral("certerror")) {
        url.AssignASCII("chrome://browser/content/aboutNetError-new.xhtml");
      }

      // fall back to the specified url in the map
      if (url.IsEmpty()) {
        url.AssignASCII(redir.url);
      }

      nsCOMPtr<nsIChannel> tempChannel;
      nsCOMPtr<nsIURI> tempURI;
      rv = NS_NewURI(getter_AddRefs(tempURI), url);
      NS_ENSURE_SUCCESS(rv, rv);

      // If tempURI links to an external URI (i.e. something other than
      // chrome:// or resource://) then set the result principal URI on the
      // load info which forces the channel prncipal to reflect the displayed
      // URL rather then being the systemPrincipal.
      bool isUIResource = false;
      rv = NS_URIChainHasFlags(tempURI, nsIProtocolHandler::URI_IS_UI_RESOURCE,
                               &isUIResource);
      NS_ENSURE_SUCCESS(rv, rv);

      rv = NS_NewChannelInternal(getter_AddRefs(tempChannel),
                                 tempURI,
                                 aLoadInfo);
      NS_ENSURE_SUCCESS(rv, rv);

      if (!isUIResource) {
        aLoadInfo->SetResultPrincipalURI(tempURI);
      }
      tempChannel->SetOriginalURI(aURI);

      NS_ADDREF(*result = tempChannel);
      return rv;
    }
  }

  return NS_ERROR_ILLEGAL_VALUE;
}

NS_IMETHODIMP
AboutRedirector::GetURIFlags(nsIURI *aURI, uint32_t *result)
{
  NS_ENSURE_ARG_POINTER(aURI);

  nsAutoCString name = GetAboutModuleName(aURI);

  for (auto & redir : kRedirMap) {
    if (name.Equals(redir.id)) {
      *result = redir.flags;
      return NS_OK;
    }
  }

  return NS_ERROR_ILLEGAL_VALUE;
}

nsresult
AboutRedirector::Create(nsISupports *aOuter, REFNSIID aIID, void **result)
{
  AboutRedirector* about = new AboutRedirector();
  if (about == nullptr)
    return NS_ERROR_OUT_OF_MEMORY;
  NS_ADDREF(about);
  nsresult rv = about->QueryInterface(aIID, result);
  NS_RELEASE(about);
  return rv;
}

} // namespace browser
} // namespace mozilla
