toolkit/components/antitracking/TemporaryAccessGrantObserver.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "TemporaryAccessGrantObserver.h"
   8
   9 #include "mozilla/AppShutdown.h"
  10 #include "mozilla/ClearOnShutdown.h"
  11 #include "mozilla/PermissionManager.h"
  12 #include "mozilla/Services.h"
  13 #include "nsIObserverService.h"
  14 #include "nsTHashtable.h"
  15 #include "nsXULAppAPI.h"
  16
  17 using namespace mozilla;
  18
  19 StaticAutoPtr<TemporaryAccessGrantObserver::ObserversTable>
  20     TemporaryAccessGrantObserver::sObservers;
  21
  22 TemporaryAccessGrantObserver::TemporaryAccessGrantObserver(
  23     PermissionManager* aPM, nsIPrincipal* aPrincipal, const nsACString& aType)
  24     : mPM(aPM), mPrincipal(aPrincipal), mType(aType) {
  25   MOZ_ASSERT(XRE_IsParentProcess(),
  26              "Enforcing temporary access grant lifetimes can only be done in "
  27              "the parent process");
  28 }
  29
  30 NS_IMPL_ISUPPORTS(TemporaryAccessGrantObserver, nsIObserver, nsINamed)
  31
  32 // static
  33 void TemporaryAccessGrantObserver::Create(PermissionManager* aPM,
  34                                           nsIPrincipal* aPrincipal,
  35                                           const nsACString& aType) {
  36   MOZ_ASSERT(XRE_IsParentProcess());
  37   MOZ_ASSERT(NS_IsMainThread());
  38
  39   if (!sObservers) {
  40     // Prevent us from resurrection during shutdown. Note that ClearOnShutdown
  41     // would kill us right away in this case, but we want to return with no-op.
  42     if (AppShutdown::IsInOrBeyond(ShutdownPhase::XPCOMWillShutdown)) {
  43       return;
  44     }
  45     sObservers = new ObserversTable();
  46     // PermissionManager shuts down in this phase, so we should avoid to keep
  47     // references to it for longer. Clearing will cancel all outstanding timers
  48     // and clear the table. This is safe as the timers have been created from
  49     // and target to the main thread (so we do not need an explicit Cancel).
  50     ClearOnShutdown(&sObservers, ShutdownPhase::XPCOMWillShutdown);
  51   }
  52   sObservers->LookupOrInsertWith(
  53       std::make_pair(nsCOMPtr<nsIPrincipal>(aPrincipal), nsCString(aType)),
  54       [&]() -> nsCOMPtr<nsITimer> {
  55         // Only create a new observer if we don't have a matching
  56         // entry in our hashtable.
  57         nsCOMPtr<nsITimer> timer;
  58         RefPtr<TemporaryAccessGrantObserver> observer =
  59             new TemporaryAccessGrantObserver(aPM, aPrincipal, aType);
  60         nsresult rv = NS_NewTimerWithObserver(getter_AddRefs(timer), observer,
  61                                               24 * 60 * 60 * 1000,  // 24 hours
  62                                               nsITimer::TYPE_ONE_SHOT);
  63
  64         if (NS_SUCCEEDED(rv)) {
  65           observer->SetTimer(timer);
  66           return timer;
  67         }
  68         timer->Cancel();
  69         return nullptr;
  70       });
  71 }
  72
  73 void TemporaryAccessGrantObserver::SetTimer(nsITimer* aTimer) {
  74   mTimer = aTimer;
  75 }
  76
  77 NS_IMETHODIMP
  78 TemporaryAccessGrantObserver::Observe(nsISupports* aSubject, const char* aTopic,
  79                                       const char16_t* aData) {
  80   if (strcmp(aTopic, NS_TIMER_CALLBACK_TOPIC) == 0) {
  81     Unused << mPM->RemoveFromPrincipal(mPrincipal, mType);
  82
  83     MOZ_ASSERT(sObservers);
  84     sObservers->Remove(std::make_pair(mPrincipal, mType));
  85   }
  86
  87   return NS_OK;
  88 }
  89
  90 NS_IMETHODIMP
  91 TemporaryAccessGrantObserver::GetName(nsACString& aName) {
  92   aName.AssignLiteral("TemporaryAccessGrantObserver");
  93   return NS_OK;
  94 }