/* 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 "nsContentBlocker.h"

#include "nsIContent.h"

#include "nsIURI.h"

#include "nsIServiceManager.h"

#include "nsIDocShellTreeItem.h"

#include "nsIPrefService.h"

#include "nsIPrefBranch.h"

#include "nsIDocShell.h"

#include "nsString.h"

#include "nsContentPolicyUtils.h"

#include "nsIObjectLoadingContent.h"

#include "mozilla/ArrayUtils.h"

#include "nsContentUtils.h"

// Possible behavior pref values

// Those map to the nsIPermissionManager values where possible

#define BEHAVIOR_ACCEPT nsIPermissionManager::ALLOW_ACTION

#define BEHAVIOR_REJECT nsIPermissionManager::DENY_ACTION

#define BEHAVIOR_NOFOREIGN 3

// From nsIContentPolicy

static const char *kTypeString[] = {

                                    "other",

                                    "script",

                                    "image",

                                    "stylesheet",

                                    "object",

                                    "document",

                                    "subdocument",

                                    "refresh",

                                    "xbl",

                                    "ping",

                                    "xmlhttprequest",

                                    "objectsubrequest",

                                    "dtd",

                                    "font",

                                    "media",

                                    "websocket",

                                    "csp_report",

                                    "xslt",

                                    "beacon",

                                    "fetch",

                                    "image",

                                    "manifest",

                                    "", // TYPE_INTERNAL_SCRIPT

                                    "", // TYPE_INTERNAL_WORKER

                                    "", // TYPE_INTERNAL_SHARED_WORKER

                                    "", // TYPE_INTERNAL_EMBED

                                    "", // TYPE_INTERNAL_OBJECT

                                    "", // TYPE_INTERNAL_FRAME

                                    "", // TYPE_INTERNAL_IFRAME

                                    "", // TYPE_INTERNAL_AUDIO

                                    "", // TYPE_INTERNAL_VIDEO

                                    "", // TYPE_INTERNAL_TRACK

                                    "", // TYPE_INTERNAL_XMLHTTPREQUEST

                                    "", // TYPE_INTERNAL_EVENTSOURCE

                                    "", // TYPE_INTERNAL_SERVICE_WORKER

                                    "", // TYPE_INTERNAL_SCRIPT_PRELOAD

                                    "", // TYPE_INTERNAL_IMAGE

                                    "", // TYPE_INTERNAL_IMAGE_PRELOAD

                                    "", // TYPE_INTERNAL_STYLESHEET

                                    "", // TYPE_INTERNAL_STYLESHEET_PRELOAD

                                    "", // TYPE_INTERNAL_IMAGE_FAVICON

                                    "", // TYPE_INTERNAL_WORKERS_IMPORT_SCRIPTS

                                    "saveas_download",

                                    "speculative",

};

#define NUMBER_OF_TYPES MOZ_ARRAY_LENGTH(kTypeString)

uint8_t nsContentBlocker::mBehaviorPref[NUMBER_OF_TYPES];

NS_IMPL_ISUPPORTS(nsContentBlocker,

                  nsIContentPolicy,

                  nsIObserver,

                  nsISupportsWeakReference)

nsContentBlocker::nsContentBlocker()

{

  memset(mBehaviorPref, BEHAVIOR_ACCEPT, NUMBER_OF_TYPES);

}

nsresult

nsContentBlocker::Init()

{

  nsresult rv;

  mPermissionManager = do_GetService(NS_PERMISSIONMANAGER_CONTRACTID, &rv);

  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIPrefService> prefService = do_GetService(NS_PREFSERVICE_CONTRACTID, &rv);

  NS_ENSURE_SUCCESS(rv, rv);

  nsCOMPtr<nsIPrefBranch> prefBranch;

  rv = prefService->GetBranch("permissions.default.", getter_AddRefs(prefBranch));

  NS_ENSURE_SUCCESS(rv, rv);

  // Migrate old image blocker pref

  nsCOMPtr<nsIPrefBranch> oldPrefBranch;

  oldPrefBranch = do_QueryInterface(prefService);

  int32_t oldPref;

  rv = oldPrefBranch->GetIntPref("network.image.imageBehavior", &oldPref);

  if (NS_SUCCEEDED(rv) && oldPref) {

    int32_t newPref;

    switch (oldPref) {

      default:

        newPref = BEHAVIOR_ACCEPT;

        break;

      case 1:

        newPref = BEHAVIOR_NOFOREIGN;

        break;

      case 2:

        newPref = BEHAVIOR_REJECT;

        break;

    }

    prefBranch->SetIntPref("image", newPref);

    oldPrefBranch->ClearUserPref("network.image.imageBehavior");

  }

  // The branch is not a copy of the prefservice, but a new object, because

  // it is a non-default branch. Adding obeservers to it will only work if

  // we make sure that the object doesn't die. So, keep a reference to it.

  mPrefBranchInternal = do_QueryInterface(prefBranch, &rv);

  NS_ENSURE_SUCCESS(rv, rv);

  rv = mPrefBranchInternal->AddObserver("", this, true);

  PrefChanged(prefBranch, nullptr);

  return rv;

}

#undef  LIMIT

#define LIMIT(x, low, high, default) ((x) >= (low) && (x) <= (high) ? (x) : (default))

void

nsContentBlocker::PrefChanged(nsIPrefBranch *aPrefBranch,

                              const char    *aPref)

{

  int32_t val;

#define PREF_CHANGED(_P) (!aPref || !strcmp(aPref, _P))

  for(uint32_t i = 0; i < NUMBER_OF_TYPES; ++i) {

    if (*kTypeString[i] &&

        PREF_CHANGED(kTypeString[i]) &&

        NS_SUCCEEDED(aPrefBranch->GetIntPref(kTypeString[i], &val)))

      mBehaviorPref[i] = LIMIT(val, 1, 3, 1);

  }

}

// nsIContentPolicy Implementation

NS_IMETHODIMP

nsContentBlocker::ShouldLoad(nsIURI           *aContentLocation,

                             nsILoadInfo      *aLoadInfo,

                             const nsACString &aMimeGuess,

                             int16_t          *aDecision)

{

  uint32_t contentType = aLoadInfo->GetExternalContentPolicyType();

  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->LoadingPrincipal();

  nsCOMPtr<nsIURI> requestingLocation;

  if (loadingPrincipal) {

    loadingPrincipal->GetURI(getter_AddRefs(requestingLocation));

  }

  MOZ_ASSERT(contentType == nsContentUtils::InternalContentPolicyTypeToExternal(contentType),

             "We should only see external content policy types here.");

  *aDecision = nsIContentPolicy::ACCEPT;

  nsresult rv;

  // Ony support NUMBER_OF_TYPES content types. that all there is at the

  // moment, but you never know...

  if (contentType > NUMBER_OF_TYPES)

    return NS_OK;

  // we can't do anything without this

  if (!aContentLocation)

    return NS_OK;

  // The final type of an object tag may mutate before it reaches

  // shouldProcess, so we cannot make any sane blocking decisions here

  if (contentType == nsIContentPolicy::TYPE_OBJECT)

    return NS_OK;

  // we only want to check http, https, ftp

  // for chrome:// and resources and others, no need to check.

  nsAutoCString scheme;

  aContentLocation->GetScheme(scheme);

  if (!scheme.LowerCaseEqualsLiteral("ftp") &&

      !scheme.LowerCaseEqualsLiteral("http") &&

      !scheme.LowerCaseEqualsLiteral("https"))

    return NS_OK;

  bool shouldLoad, fromPrefs;

  rv = TestPermission(aContentLocation, requestingLocation, contentType,

                      &shouldLoad, &fromPrefs);

  NS_ENSURE_SUCCESS(rv, rv);

  if (!shouldLoad) {

    if (fromPrefs) {

      *aDecision = nsIContentPolicy::REJECT_TYPE;

    } else {

      *aDecision = nsIContentPolicy::REJECT_SERVER;

    }

  }

  return NS_OK;

}

NS_IMETHODIMP

nsContentBlocker::ShouldProcess(nsIURI           *aContentLocation,

                                nsILoadInfo      *aLoadInfo,

                                const nsACString &aMimeGuess,

                                int16_t          *aDecision)

{

  uint32_t contentType = aLoadInfo->GetExternalContentPolicyType();

  nsCOMPtr<nsISupports> requestingContext = aLoadInfo->GetLoadingContext();

  nsCOMPtr<nsIPrincipal> loadingPrincipal = aLoadInfo->LoadingPrincipal();

  nsCOMPtr<nsIURI> requestingLocation;

  if (loadingPrincipal) {

    loadingPrincipal->GetURI(getter_AddRefs(requestingLocation));

  }

  MOZ_ASSERT(contentType == nsContentUtils::InternalContentPolicyTypeToExternal(contentType),

             "We should only see external content policy types here.");

  // For loads where requesting context is chrome, we should just

  // accept.  Those are most likely toplevel loads in windows, and

  // chrome generally knows what it's doing anyway.

  nsCOMPtr<nsIDocShellTreeItem> item =

    do_QueryInterface(NS_CP_GetDocShellFromContext(requestingContext));

  if (item && item->ItemType() == nsIDocShellTreeItem::typeChrome) {

    *aDecision = nsIContentPolicy::ACCEPT;

    return NS_OK;

  }

  // For objects, we only check policy in shouldProcess, as the final type isn't

  // determined until the channel is open -- We don't want to block images in

  // object tags because plugins are disallowed.

  // NOTE that this bypasses the aContentLocation checks in ShouldLoad - this is

  // intentional, as aContentLocation may be null for plugins that load by type

  // (e.g. java)

  if (contentType == nsIContentPolicy::TYPE_OBJECT) {

    *aDecision = nsIContentPolicy::ACCEPT;

    bool shouldLoad, fromPrefs;

    nsresult rv = TestPermission(aContentLocation, requestingLocation,

                                 contentType, &shouldLoad, &fromPrefs);

    NS_ENSURE_SUCCESS(rv, rv);

    if (!shouldLoad) {

      if (fromPrefs) {

        *aDecision = nsIContentPolicy::REJECT_TYPE;

      } else {

        *aDecision = nsIContentPolicy::REJECT_SERVER;

      }

    }

    return NS_OK;

  }

  // This isn't a load from chrome or an object tag - Just do a ShouldLoad()

  // check -- we want the same answer here

  return ShouldLoad(aContentLocation, aLoadInfo, aMimeGuess, aDecision);

}

nsresult

nsContentBlocker::TestPermission(nsIURI *aCurrentURI,

                                 nsIURI *aFirstURI,

                                 int32_t aContentType,

                                 bool *aPermission,

                                 bool *aFromPrefs)

{

  *aFromPrefs = false;

  nsresult rv;

  if (!*kTypeString[aContentType - 1]) {

    // Disallow internal content policy types, they should not be used here.

    *aPermission = false;

    return NS_OK;

  }

  // This default will also get used if there is an unknown value in the

  // permission list, or if the permission manager returns unknown values.

  *aPermission = true;

  // check the permission list first; if we find an entry, it overrides

  // default prefs.

  // Don't forget the aContentType ranges from 1..8, while the

  // array is indexed 0..7

  // All permissions tested by this method are preload permissions, so don't

  // bother actually checking with the permission manager unless we have a

  // preload permission.

  uint32_t permission = nsIPermissionManager::UNKNOWN_ACTION;

  if (mPermissionManager->GetHasPreloadPermissions()) {

    rv = mPermissionManager->TestPermission(aCurrentURI,

                                            kTypeString[aContentType - 1],

                                            &permission);

    NS_ENSURE_SUCCESS(rv, rv);

  }

  // If there is nothing on the list, use the default.

  if (!permission) {

    permission = mBehaviorPref[aContentType - 1];

    *aFromPrefs = true;

  }

  // Use the fact that the nsIPermissionManager values map to

  // the BEHAVIOR_* values above.

  switch (permission) {

  case BEHAVIOR_ACCEPT:

    *aPermission = true;

    break;

  case BEHAVIOR_REJECT:

    *aPermission = false;

    break;

  case BEHAVIOR_NOFOREIGN:

    // Third party checking

    // Need a requesting uri for third party checks to work.

    if (!aFirstURI)

      return NS_OK;

    bool trustedSource = false;

    rv = aFirstURI->SchemeIs("chrome", &trustedSource);

    NS_ENSURE_SUCCESS(rv,rv);

    if (!trustedSource) {

      rv = aFirstURI->SchemeIs("resource", &trustedSource);

      NS_ENSURE_SUCCESS(rv,rv);

    }

    if (trustedSource)

      return NS_OK;

    // compare tails of names checking to see if they have a common domain

    // we do this by comparing the tails of both names where each tail

    // includes at least one dot

    // A more generic method somewhere would be nice

    nsAutoCString currentHost;

    rv = aCurrentURI->GetAsciiHost(currentHost);

    NS_ENSURE_SUCCESS(rv, rv);

    // Search for two dots, starting at the end.

    // If there are no two dots found, ++dot will turn to zero,

    // that will return the entire string.

    int32_t dot = currentHost.RFindChar('.');

    dot = currentHost.RFindChar('.', dot-1);

    ++dot;

    // Get the domain, ie the last part of the host (www.domain.com -> domain.com)

    // This will break on co.uk

    const nsACString& tail =

      Substring(currentHost, dot, currentHost.Length() - dot);

    nsAutoCString firstHost;

    rv = aFirstURI->GetAsciiHost(firstHost);

    NS_ENSURE_SUCCESS(rv, rv);

    // If the tail is longer then the whole firstHost, it will never match

    if (firstHost.Length() < tail.Length()) {

      *aPermission = false;

      return NS_OK;

    }

    // Get the last part of the firstUri with the same length as |tail|

    const nsACString& firstTail =

      Substring(firstHost, firstHost.Length() - tail.Length(), tail.Length());

    // Check that both tails are the same, and that just before the tail in

    // |firstUri| there is a dot. That means both url are in the same domain

    if ((firstHost.Length() > tail.Length() &&

         firstHost.CharAt(firstHost.Length() - tail.Length() - 1) != '.') ||

        !tail.Equals(firstTail)) {

      *aPermission = false;

    }

    break;

  }

  return NS_OK;

}

NS_IMETHODIMP

nsContentBlocker::Observe(nsISupports     *aSubject,

                          const char      *aTopic,

                          const char16_t *aData)

{

  NS_ASSERTION(!strcmp(NS_PREFBRANCH_PREFCHANGE_TOPIC_ID, aTopic),

               "unexpected topic - we only deal with pref changes!");

  if (mPrefBranchInternal)

    PrefChanged(mPrefBranchInternal, NS_LossyConvertUTF16toASCII(aData).get());

  return NS_OK;

}