netwerk/dns/nsHostResolver.cpp

   1 /* vim:set ts=4 sw=2 sts=2 et cin: */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsIThreadPool.h"
   7 #if defined(HAVE_RES_NINIT)
   8 #  include <sys/types.h>
   9 #  include <netinet/in.h>
  10 #  include <arpa/inet.h>
  11 #  include <arpa/nameser.h>
  12 #  include <resolv.h>
  13 #  define RES_RETRY_ON_FAILURE
  14 #endif
  15
  16 #include <stdlib.h>
  17 #include <ctime>
  18 #include "nsHostResolver.h"
  19 #include "nsError.h"
  20 #include "nsISupports.h"
  21 #include "nsISupportsUtils.h"
  22 #include "nsIThreadManager.h"
  23 #include "nsComponentManagerUtils.h"
  24 #include "nsNetUtil.h"
  25 #include "nsPrintfCString.h"
  26 #include "nsXPCOMCIDInternal.h"
  27 #include "prthread.h"
  28 #include "prerror.h"
  29 #include "prtime.h"
  30 #include "mozilla/Logging.h"
  31 #include "PLDHashTable.h"
  32 #include "nsQueryObject.h"
  33 #include "nsURLHelper.h"
  34 #include "nsThreadUtils.h"
  35 #include "nsThreadPool.h"
  36 #include "GetAddrInfo.h"
  37 #include "TRR.h"
  38 #include "TRRQuery.h"
  39 #include "TRRService.h"
  40
  41 #include "mozilla/Atomics.h"
  42 #include "mozilla/glean/GleanMetrics.h"
  43 #include "mozilla/HashFunctions.h"
  44 #include "mozilla/TimeStamp.h"
  45 #include "mozilla/Telemetry.h"
  46 #include "mozilla/DebugOnly.h"
  47 #include "mozilla/Preferences.h"
  48 #include "mozilla/StaticPrefs_network.h"
  49 // Put DNSLogging.h at the end to avoid LOG being overwritten by other headers.
  50 #include "DNSLogging.h"
  51
  52 #ifdef XP_WIN
  53 #  include "mozilla/WindowsVersion.h"
  54 #endif  // XP_WIN
  55
  56 #ifdef MOZ_WIDGET_ANDROID
  57 #  include "mozilla/jni/Utils.h"
  58 #endif
  59
  60 #define IS_ADDR_TYPE(_type) ((_type) == nsIDNSService::RESOLVE_TYPE_DEFAULT)
  61 #define IS_OTHER_TYPE(_type) ((_type) != nsIDNSService::RESOLVE_TYPE_DEFAULT)
  62
  63 using namespace mozilla;
  64 using namespace mozilla::net;
  65
  66 // None of our implementations expose a TTL for negative responses, so we use a
  67 // constant always.
  68 static const unsigned int NEGATIVE_RECORD_LIFETIME = 60;
  69
  70 //----------------------------------------------------------------------------
  71
  72 // Use a persistent thread pool in order to avoid spinning up new threads all
  73 // the time. In particular, thread creation results in a res_init() call from
  74 // libc which is quite expensive.
  75 //
  76 // The pool dynamically grows between 0 and MaxResolverThreads() in size. New
  77 // requests go first to an idle thread. If that cannot be found and there are
  78 // fewer than MaxResolverThreads() currently in the pool a new thread is created
  79 // for high priority requests. If the new request is at a lower priority a new
  80 // thread will only be created if there are fewer than
  81 // MaxResolverThreadsAnyPriority() currently outstanding. If a thread cannot be
  82 // created or an idle thread located for the request it is queued.
  83 //
  84 // When the pool is greater than MaxResolverThreadsAnyPriority() in size a
  85 // thread will be destroyed after ShortIdleTimeoutSeconds of idle time. Smaller
  86 // pools use LongIdleTimeoutSeconds for a timeout period.
  87
  88 // for threads 1 -> MaxResolverThreadsAnyPriority()
  89 #define LongIdleTimeoutSeconds 300
  90 // for threads MaxResolverThreadsAnyPriority() + 1 -> MaxResolverThreads()
  91 #define ShortIdleTimeoutSeconds 60
  92
  93 //----------------------------------------------------------------------------
  94
  95 namespace mozilla::net {
  96 LazyLogModule gHostResolverLog("nsHostResolver");
  97 }  // namespace mozilla::net
  98
  99 //----------------------------------------------------------------------------
 100
 101 #if defined(RES_RETRY_ON_FAILURE)
 102
 103 // this class represents the resolver state for a given thread.  if we
 104 // encounter a lookup failure, then we can invoke the Reset method on an
 105 // instance of this class to reset the resolver (in case /etc/resolv.conf
 106 // for example changed).  this is mainly an issue on GNU systems since glibc
 107 // only reads in /etc/resolv.conf once per thread.  it may be an issue on
 108 // other systems as well.
 109
 110 class nsResState {
 111  public:
 112   nsResState()
 113       // initialize mLastReset to the time when this object
 114       // is created.  this means that a reset will not occur
 115       // if a thread is too young.  the alternative would be
 116       // to initialize this to the beginning of time, so that
 117       // the first failure would cause a reset, but since the
 118       // thread would have just started up, it likely would
 119       // already have current /etc/resolv.conf info.
 120       : mLastReset(PR_IntervalNow()) {}
 121
 122   bool Reset() {
 123     // reset no more than once per second
 124     if (PR_IntervalToSeconds(PR_IntervalNow() - mLastReset) < 1) {
 125       return false;
 126     }
 127
 128     mLastReset = PR_IntervalNow();
 129     auto result = res_ninit(&_res);
 130
 131     LOG(("nsResState::Reset() > 'res_ninit' returned %d", result));
 132     return (result == 0);
 133   }
 134
 135  private:
 136   PRIntervalTime mLastReset;
 137 };
 138
 139 #endif  // RES_RETRY_ON_FAILURE
 140
 141 class DnsThreadListener final : public nsIThreadPoolListener {
 142   NS_DECL_THREADSAFE_ISUPPORTS
 143   NS_DECL_NSITHREADPOOLLISTENER
 144  private:
 145   virtual ~DnsThreadListener() = default;
 146 };
 147
 148 NS_IMETHODIMP
 149 DnsThreadListener::OnThreadCreated() { return NS_OK; }
 150
 151 NS_IMETHODIMP
 152 DnsThreadListener::OnThreadShuttingDown() {
 153   DNSThreadShutdown();
 154   return NS_OK;
 155 }
 156
 157 NS_IMPL_ISUPPORTS(DnsThreadListener, nsIThreadPoolListener)
 158
 159 //----------------------------------------------------------------------------
 160
 161 static const char kPrefGetTtl[] = "network.dns.get-ttl";
 162 static const char kPrefNativeIsLocalhost[] = "network.dns.native-is-localhost";
 163 static const char kPrefThreadIdleTime[] =
 164     "network.dns.resolver-thread-extra-idle-time-seconds";
 165 static bool sGetTtlEnabled = false;
 166 mozilla::Atomic<bool, mozilla::Relaxed> gNativeIsLocalhost;
 167 mozilla::Atomic<bool, mozilla::Relaxed> sNativeHTTPSSupported{false};
 168
 169 static void DnsPrefChanged(const char* aPref, void* aSelf) {
 170   MOZ_ASSERT(NS_IsMainThread(),
 171              "Should be getting pref changed notification on main thread!");
 172
 173   MOZ_ASSERT(aSelf);
 174
 175   if (!strcmp(aPref, kPrefGetTtl)) {
 176 #ifdef DNSQUERY_AVAILABLE
 177     sGetTtlEnabled = Preferences::GetBool(kPrefGetTtl);
 178 #endif
 179   } else if (!strcmp(aPref, kPrefNativeIsLocalhost)) {
 180     gNativeIsLocalhost = Preferences::GetBool(kPrefNativeIsLocalhost);
 181   }
 182 }
 183
 184 NS_IMPL_ISUPPORTS0(nsHostResolver)
 185
 186 nsHostResolver::nsHostResolver(uint32_t maxCacheEntries,
 187                                uint32_t defaultCacheEntryLifetime,
 188                                uint32_t defaultGracePeriod)
 189     : mMaxCacheEntries(maxCacheEntries),
 190       mDefaultCacheLifetime(defaultCacheEntryLifetime),
 191       mDefaultGracePeriod(defaultGracePeriod),
 192       mIdleTaskCV(mLock, "nsHostResolver.mIdleTaskCV") {
 193   mCreationTime = PR_Now();
 194
 195   mLongIdleTimeout = TimeDuration::FromSeconds(LongIdleTimeoutSeconds);
 196   mShortIdleTimeout = TimeDuration::FromSeconds(ShortIdleTimeoutSeconds);
 197 }
 198
 199 nsHostResolver::~nsHostResolver() = default;
 200
 201 nsresult nsHostResolver::Init() MOZ_NO_THREAD_SAFETY_ANALYSIS {
 202   MOZ_ASSERT(NS_IsMainThread());
 203   if (NS_FAILED(GetAddrInfoInit())) {
 204     return NS_ERROR_FAILURE;
 205   }
 206
 207   LOG(("nsHostResolver::Init this=%p", this));
 208
 209   mShutdown = false;
 210   mNCS = NetworkConnectivityService::GetSingleton();
 211
 212   // The preferences probably haven't been loaded from the disk yet, so we
 213   // need to register a callback that will set up the experiment once they
 214   // are. We also need to explicitly set a value for the props otherwise the
 215   // callback won't be called.
 216   {
 217     DebugOnly<nsresult> rv = Preferences::RegisterCallbackAndCall(
 218         &DnsPrefChanged, kPrefGetTtl, this);
 219     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
 220                          "Could not register DNS TTL pref callback.");
 221     rv = Preferences::RegisterCallbackAndCall(&DnsPrefChanged,
 222                                               kPrefNativeIsLocalhost, this);
 223     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
 224                          "Could not register DNS pref callback.");
 225   }
 226
 227 #if defined(HAVE_RES_NINIT)
 228   // We want to make sure the system is using the correct resolver settings,
 229   // so we force it to reload those settings whenever we startup a subsequent
 230   // nsHostResolver instance.  We assume that there is no reason to do this
 231   // for the first nsHostResolver instance since that is usually created
 232   // during application startup.
 233   static int initCount = 0;
 234   if (initCount++ > 0) {
 235     auto result = res_ninit(&_res);
 236     LOG(("nsHostResolver::Init > 'res_ninit' returned %d", result));
 237   }
 238 #endif
 239
 240   // We can configure the threadpool to keep threads alive for a while after
 241   // the last ThreadFunc task has been executed.
 242   int32_t poolTimeoutSecs = Preferences::GetInt(kPrefThreadIdleTime, 60);
 243   uint32_t poolTimeoutMs;
 244   if (poolTimeoutSecs < 0) {
 245     // This means never shut down the idle threads
 246     poolTimeoutMs = UINT32_MAX;
 247   } else {
 248     // We clamp down the idle time between 0 and one hour.
 249     poolTimeoutMs =
 250         mozilla::clamped<uint32_t>(poolTimeoutSecs * 1000, 0, 3600 * 1000);
 251   }
 252
 253 #if defined(XP_WIN)
 254   // For some reason, the DNSQuery_A API doesn't work on Windows 10.
 255   // It returns a success code, but no records. We only allow
 256   // native HTTPS records on Win 11 for now.
 257   sNativeHTTPSSupported = StaticPrefs::network_dns_native_https_query_win10() ||
 258                           mozilla::IsWin11OrLater();
 259 #elif defined(MOZ_WIDGET_ANDROID)
 260   // android_res_nquery only got added in API level 29
 261   sNativeHTTPSSupported = jni::GetAPIVersion() >= 29;
 262 #elif defined(XP_LINUX) || defined(XP_MACOSX)
 263   sNativeHTTPSSupported = true;
 264 #endif
 265   LOG(("Native HTTPS records supported=%d", bool(sNativeHTTPSSupported)));
 266
 267   nsCOMPtr<nsIThreadPool> threadPool = new nsThreadPool();
 268   MOZ_ALWAYS_SUCCEEDS(threadPool->SetThreadLimit(MaxResolverThreads()));
 269   MOZ_ALWAYS_SUCCEEDS(threadPool->SetIdleThreadLimit(MaxResolverThreads()));
 270   MOZ_ALWAYS_SUCCEEDS(threadPool->SetIdleThreadTimeout(poolTimeoutMs));
 271   MOZ_ALWAYS_SUCCEEDS(
 272       threadPool->SetThreadStackSize(nsIThreadManager::kThreadPoolStackSize));
 273   MOZ_ALWAYS_SUCCEEDS(threadPool->SetName("DNS Resolver"_ns));
 274   nsCOMPtr<nsIThreadPoolListener> listener = new DnsThreadListener();
 275   threadPool->SetListener(listener);
 276   mResolverThreads = ToRefPtr(std::move(threadPool));
 277
 278   return NS_OK;
 279 }
 280
 281 void nsHostResolver::ClearPendingQueue(
 282     LinkedList<RefPtr<nsHostRecord>>& aPendingQ) {
 283   // loop through pending queue, erroring out pending lookups.
 284   if (!aPendingQ.isEmpty()) {
 285     for (const RefPtr<nsHostRecord>& rec : aPendingQ) {
 286       rec->Cancel();
 287       if (rec->IsAddrRecord()) {
 288         CompleteLookup(rec, NS_ERROR_ABORT, nullptr, rec->pb, rec->originSuffix,
 289                        rec->mTRRSkippedReason, nullptr);
 290       } else {
 291         mozilla::net::TypeRecordResultType empty(Nothing{});
 292         CompleteLookupByType(rec, NS_ERROR_ABORT, empty, rec->mTRRSkippedReason,
 293                              0, rec->pb);
 294       }
 295     }
 296   }
 297 }
 298
 299 //
 300 // FlushCache() is what we call when the network has changed. We must not
 301 // trust names that were resolved before this change. They may resolve
 302 // differently now.
 303 //
 304 // This function removes all existing resolved host entries from the hash.
 305 // Names that are in the pending queues can be left there. Entries in the
 306 // cache that have 'Resolve' set true but not 'OnQueue' are being resolved
 307 // right now, so we need to mark them to get re-resolved on completion!
 308
 309 void nsHostResolver::FlushCache(bool aTrrToo) {
 310   MutexAutoLock lock(mLock);
 311
 312   mQueue.FlushEvictionQ(mRecordDB, lock);
 313
 314   // Refresh the cache entries that are resolving RIGHT now, remove the rest.
 315   for (auto iter = mRecordDB.Iter(); !iter.Done(); iter.Next()) {
 316     nsHostRecord* record = iter.UserData();
 317     // Try to remove the record, or mark it for refresh.
 318     // By-type records are from TRR. We do not need to flush those entry
 319     // when the network has change, because they are not local.
 320     if (record->IsAddrRecord()) {
 321       RefPtr<AddrHostRecord> addrRec = do_QueryObject(record);
 322       MOZ_ASSERT(addrRec);
 323       if (addrRec->RemoveOrRefresh(aTrrToo)) {
 324         mQueue.MaybeRemoveFromQ(record, lock);
 325         LOG(("Removing (%s) Addr record from mRecordDB", record->host.get()));
 326         iter.Remove();
 327       }
 328     } else if (aTrrToo) {
 329       // remove by type records
 330       LOG(("Removing (%s) type record from mRecordDB", record->host.get()));
 331       iter.Remove();
 332     }
 333   }
 334 }
 335
 336 void nsHostResolver::Shutdown() {
 337   LOG(("Shutting down host resolver.\n"));
 338
 339   {
 340     DebugOnly<nsresult> rv =
 341         Preferences::UnregisterCallback(&DnsPrefChanged, kPrefGetTtl, this);
 342     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
 343                          "Could not unregister DNS TTL pref callback.");
 344   }
 345
 346   LinkedList<RefPtr<nsHostRecord>> pendingQHigh, pendingQMed, pendingQLow,
 347       evictionQ;
 348
 349   {
 350     MutexAutoLock lock(mLock);
 351
 352     mShutdown = true;
 353
 354     if (mNumIdleTasks) {
 355       mIdleTaskCV.NotifyAll();
 356     }
 357
 358     mQueue.ClearAll(
 359         [&](nsHostRecord* aRec) {
 360           mLock.AssertCurrentThreadOwns();
 361           if (aRec->IsAddrRecord()) {
 362             CompleteLookupLocked(aRec, NS_ERROR_ABORT, nullptr, aRec->pb,
 363                                  aRec->originSuffix, aRec->mTRRSkippedReason,
 364                                  nullptr, lock);
 365           } else {
 366             mozilla::net::TypeRecordResultType empty(Nothing{});
 367             CompleteLookupByTypeLocked(aRec, NS_ERROR_ABORT, empty,
 368                                        aRec->mTRRSkippedReason, 0, aRec->pb,
 369                                        lock);
 370           }
 371         },
 372         lock);
 373
 374     for (const auto& data : mRecordDB.Values()) {
 375       data->Cancel();
 376     }
 377     // empty host database
 378     mRecordDB.Clear();
 379
 380     mNCS = nullptr;
 381   }
 382
 383   // Shutdown the resolver threads, but with a timeout of 2 seconds (prefable).
 384   // If the timeout is exceeded, any stuck threads will be leaked.
 385   mResolverThreads->ShutdownWithTimeout(
 386       StaticPrefs::network_dns_resolver_shutdown_timeout_ms());
 387
 388   {
 389     mozilla::DebugOnly<nsresult> rv = GetAddrInfoShutdown();
 390     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Failed to shutdown GetAddrInfo");
 391   }
 392 }
 393
 394 nsresult nsHostResolver::GetHostRecord(
 395     const nsACString& host, const nsACString& aTrrServer, uint16_t type,
 396     nsIDNSService::DNSFlags flags, uint16_t af, bool pb,
 397     const nsCString& originSuffix, nsHostRecord** result) {
 398   MutexAutoLock lock(mLock);
 399   nsHostKey key(host, aTrrServer, type, flags, af, pb, originSuffix);
 400
 401   RefPtr<nsHostRecord> rec =
 402       mRecordDB.LookupOrInsertWith(key, [&] { return InitRecord(key); });
 403   if (rec->IsAddrRecord()) {
 404     RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
 405     if (addrRec->addr) {
 406       return NS_ERROR_FAILURE;
 407     }
 408   }
 409
 410   if (rec->mResolving) {
 411     return NS_ERROR_FAILURE;
 412   }
 413
 414   *result = rec.forget().take();
 415   return NS_OK;
 416 }
 417
 418 nsHostRecord* nsHostResolver::InitRecord(const nsHostKey& key) {
 419   if (IS_ADDR_TYPE(key.type)) {
 420     return new AddrHostRecord(key);
 421   }
 422   return new TypeHostRecord(key);
 423 }
 424
 425 already_AddRefed<nsHostRecord> nsHostResolver::InitLoopbackRecord(
 426     const nsHostKey& key, nsresult* aRv) {
 427   MOZ_ASSERT(aRv);
 428   MOZ_ASSERT(IS_ADDR_TYPE(key.type));
 429
 430   *aRv = NS_ERROR_FAILURE;
 431   RefPtr<nsHostRecord> rec = InitRecord(key);
 432
 433   nsTArray<NetAddr> addresses;
 434   NetAddr addr;
 435   if (key.af == PR_AF_INET || key.af == PR_AF_UNSPEC) {
 436     MOZ_RELEASE_ASSERT(NS_SUCCEEDED(addr.InitFromString("127.0.0.1"_ns)));
 437     addresses.AppendElement(addr);
 438   }
 439   if (key.af == PR_AF_INET6 || key.af == PR_AF_UNSPEC) {
 440     MOZ_RELEASE_ASSERT(NS_SUCCEEDED(addr.InitFromString("::1"_ns)));
 441     addresses.AppendElement(addr);
 442   }
 443
 444   RefPtr<AddrInfo> ai =
 445       new AddrInfo(rec->host, DNSResolverType::Native, 0, std::move(addresses));
 446
 447   RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
 448   MutexAutoLock lock(addrRec->addr_info_lock);
 449   addrRec->addr_info = ai;
 450   addrRec->SetExpiration(TimeStamp::NowLoRes(), mDefaultCacheLifetime,
 451                          mDefaultGracePeriod);
 452   addrRec->negative = false;
 453
 454   *aRv = NS_OK;
 455   return rec.forget();
 456 }
 457
 458 static bool IsNativeHTTPSEnabled() {
 459   if (!StaticPrefs::network_dns_native_https_query()) {
 460     return false;
 461   }
 462   return sNativeHTTPSSupported;
 463 }
 464
 465 nsresult nsHostResolver::ResolveHost(const nsACString& aHost,
 466                                      const nsACString& aTrrServer,
 467                                      int32_t aPort, uint16_t type,
 468                                      const OriginAttributes& aOriginAttributes,
 469                                      nsIDNSService::DNSFlags flags, uint16_t af,
 470                                      nsResolveHostCallback* aCallback) {
 471   nsAutoCString host(aHost);
 472   NS_ENSURE_TRUE(!host.IsEmpty(), NS_ERROR_UNEXPECTED);
 473
 474   nsAutoCString originSuffix;
 475   aOriginAttributes.CreateSuffix(originSuffix);
 476   LOG(("Resolving host [%s]<%s>%s%s type %d. [this=%p]\n", host.get(),
 477        originSuffix.get(), flags & RES_BYPASS_CACHE ? " - bypassing cache" : "",
 478        flags & RES_REFRESH_CACHE ? " - refresh cache" : "", type, this));
 479
 480   // ensure that we are working with a valid hostname before proceeding.  see
 481   // bug 304904 for details.
 482   if (!net_IsValidHostName(host)) {
 483     return NS_ERROR_UNKNOWN_HOST;
 484   }
 485
 486   // If TRR is disabled we can return immediately if the native API is disabled
 487   if (!IsNativeHTTPSEnabled() && IS_OTHER_TYPE(type) &&
 488       Mode() == nsIDNSService::MODE_TRROFF) {
 489     return NS_ERROR_UNKNOWN_HOST;
 490   }
 491
 492   // Used to try to parse to an IP address literal.
 493   NetAddr tempAddr;
 494   if (IS_OTHER_TYPE(type) && (NS_SUCCEEDED(tempAddr.InitFromString(host)))) {
 495     // For by-type queries the host cannot be IP literal.
 496     return NS_ERROR_UNKNOWN_HOST;
 497   }
 498
 499   RefPtr<nsResolveHostCallback> callback(aCallback);
 500   // if result is set inside the lock, then we need to issue the
 501   // callback before returning.
 502   RefPtr<nsHostRecord> result;
 503   nsresult status = NS_OK, rv = NS_OK;
 504   {
 505     MutexAutoLock lock(mLock);
 506
 507     if (mShutdown) {
 508       return NS_ERROR_NOT_INITIALIZED;
 509     }
 510
 511     // check to see if there is already an entry for this |host|
 512     // in the hash table.  if so, then check to see if we can't
 513     // just reuse the lookup result.  otherwise, if there are
 514     // any pending callbacks, then add to pending callbacks queue,
 515     // and return.  otherwise, add ourselves as first pending
 516     // callback, and proceed to do the lookup.
 517
 518     Maybe<nsCString> originHost;
 519     if (StaticPrefs::network_dns_port_prefixed_qname_https_rr() &&
 520         type == nsIDNSService::RESOLVE_TYPE_HTTPSSVC && aPort != -1 &&
 521         aPort != 443) {
 522       originHost = Some(host);
 523       host = nsPrintfCString("_%d._https.%s", aPort, host.get());
 524       LOG(("  Using port prefixed host name [%s]", host.get()));
 525     }
 526
 527     bool excludedFromTRR = false;
 528     if (TRRService::Get() && TRRService::Get()->IsExcludedFromTRR(host)) {
 529       flags |= nsIDNSService::RESOLVE_DISABLE_TRR;
 530       excludedFromTRR = true;
 531
 532       if (!aTrrServer.IsEmpty()) {
 533         return NS_ERROR_UNKNOWN_HOST;
 534       }
 535     }
 536
 537     nsHostKey key(host, aTrrServer, type, flags, af,
 538                   (aOriginAttributes.mPrivateBrowsingId > 0), originSuffix);
 539
 540     // Check if we have a localhost domain, if so hardcode to loopback
 541     if (IS_ADDR_TYPE(type) && IsLoopbackHostname(host)) {
 542       nsresult rv;
 543       RefPtr<nsHostRecord> result = InitLoopbackRecord(key, &rv);
 544       if (NS_WARN_IF(NS_FAILED(rv))) {
 545         return rv;
 546       }
 547       MOZ_ASSERT(result);
 548       aCallback->OnResolveHostComplete(this, result, NS_OK);
 549       return NS_OK;
 550     }
 551
 552     RefPtr<nsHostRecord> rec =
 553         mRecordDB.LookupOrInsertWith(key, [&] { return InitRecord(key); });
 554
 555     RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
 556     MOZ_ASSERT(rec, "Record should not be null");
 557     MOZ_ASSERT((IS_ADDR_TYPE(type) && rec->IsAddrRecord() && addrRec) ||
 558                (IS_OTHER_TYPE(type) && !rec->IsAddrRecord()));
 559
 560     if (IS_OTHER_TYPE(type) && originHost) {
 561       RefPtr<TypeHostRecord> typeRec = do_QueryObject(rec);
 562       typeRec->mOriginHost = std::move(originHost);
 563     }
 564
 565     if (excludedFromTRR) {
 566       rec->RecordReason(TRRSkippedReason::TRR_EXCLUDED);
 567     }
 568
 569     if (!(flags & RES_BYPASS_CACHE) &&
 570         rec->HasUsableResult(TimeStamp::NowLoRes(), flags)) {
 571       result = FromCache(rec, host, type, status, lock);
 572     } else if (addrRec && addrRec->addr) {
 573       // if the host name is an IP address literal and has been
 574       // parsed, go ahead and use it.
 575       LOG(("  Using cached address for IP Literal [%s].\n", host.get()));
 576       result = FromCachedIPLiteral(rec);
 577     } else if (addrRec && NS_SUCCEEDED(tempAddr.InitFromString(host))) {
 578       // try parsing the host name as an IP address literal to short
 579       // circuit full host resolution.  (this is necessary on some
 580       // platforms like Win9x.  see bug 219376 for more details.)
 581       LOG(("  Host is IP Literal [%s].\n", host.get()));
 582       result = FromIPLiteral(addrRec, tempAddr);
 583     } else if (mQueue.PendingCount() >= MAX_NON_PRIORITY_REQUESTS &&
 584                !IsHighPriority(flags) && !rec->mResolving) {
 585       LOG(
 586           ("  Lookup queue full: dropping %s priority request for "
 587            "host [%s].\n",
 588            IsMediumPriority(flags) ? "medium" : "low", host.get()));
 589       if (IS_ADDR_TYPE(type)) {
 590         Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_OVERFLOW);
 591       }
 592       // This is a lower priority request and we are swamped, so refuse it.
 593       rv = NS_ERROR_DNS_LOOKUP_QUEUE_FULL;
 594
 595       // Check if the offline flag is set.
 596     } else if (flags & RES_OFFLINE) {
 597       LOG(("  Offline request for host [%s]; ignoring.\n", host.get()));
 598       rv = NS_ERROR_OFFLINE;
 599
 600       // We do not have a valid result till here.
 601       // A/AAAA request can check for an alternative entry like AF_UNSPEC.
 602       // Otherwise we need to start a new query.
 603     } else if (!rec->mResolving) {
 604       result =
 605           FromUnspecEntry(rec, host, aTrrServer, originSuffix, type, flags, af,
 606                           aOriginAttributes.mPrivateBrowsingId > 0, status);
 607       // If this is a by-type request or if no valid record was found
 608       // in the cache or this is an AF_UNSPEC request, then start a
 609       // new lookup.
 610       if (!result) {
 611         LOG(("  No usable record in cache for host [%s] type %d.", host.get(),
 612              type));
 613
 614         if (flags & RES_REFRESH_CACHE) {
 615           rec->Invalidate();
 616         }
 617
 618         // Add callback to the list of pending callbacks.
 619         rec->mCallbacks.insertBack(callback);
 620         rec->flags = flags;
 621         rv = NameLookup(rec, lock);
 622         if (IS_ADDR_TYPE(type)) {
 623           Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2,
 624                                 METHOD_NETWORK_FIRST);
 625         }
 626         if (NS_FAILED(rv) && callback->isInList()) {
 627           callback->remove();
 628         } else {
 629           LOG(
 630               ("  DNS lookup for host [%s] blocking "
 631                "pending 'getaddrinfo' or trr query: "
 632                "callback [%p]",
 633                host.get(), callback.get()));
 634         }
 635       }
 636     } else {
 637       LOG(
 638           ("  Host [%s] is being resolved. Appending callback "
 639            "[%p].",
 640            host.get(), callback.get()));
 641
 642       rec->mCallbacks.insertBack(callback);
 643
 644       if (rec && rec->onQueue()) {
 645         Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2,
 646                               METHOD_NETWORK_SHARED);
 647
 648         // Consider the case where we are on a pending queue of
 649         // lower priority than the request is being made at.
 650         // In that case we should upgrade to the higher queue.
 651
 652         if (IsHighPriority(flags) && !IsHighPriority(rec->flags)) {
 653           // Move from (low|med) to high.
 654           mQueue.MoveToAnotherPendingQ(rec, flags, lock);
 655           rec->flags = flags;
 656           ConditionallyCreateThread(rec);
 657         } else if (IsMediumPriority(flags) && IsLowPriority(rec->flags)) {
 658           // Move from low to med.
 659           mQueue.MoveToAnotherPendingQ(rec, flags, lock);
 660           rec->flags = flags;
 661           mIdleTaskCV.Notify();
 662         }
 663       }
 664     }
 665
 666     if (result && callback->isInList()) {
 667       callback->remove();
 668     }
 669   }  // lock
 670
 671   if (result) {
 672     callback->OnResolveHostComplete(this, result, status);
 673   }
 674
 675   return rv;
 676 }
 677
 678 already_AddRefed<nsHostRecord> nsHostResolver::FromCache(
 679     nsHostRecord* aRec, const nsACString& aHost, uint16_t aType,
 680     nsresult& aStatus, const MutexAutoLock& aLock) {
 681   LOG(("  Using cached record for host [%s].\n",
 682        nsPromiseFlatCString(aHost).get()));
 683
 684   // put reference to host record on stack...
 685   RefPtr<nsHostRecord> result = aRec;
 686   if (IS_ADDR_TYPE(aType)) {
 687     Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_HIT);
 688   }
 689
 690   // For entries that are in the grace period
 691   // or all cached negative entries, use the cache but start a new
 692   // lookup in the background
 693   ConditionallyRefreshRecord(aRec, aHost, aLock);
 694
 695   if (aRec->negative) {
 696     LOG(("  Negative cache entry for host [%s].\n",
 697          nsPromiseFlatCString(aHost).get()));
 698     if (IS_ADDR_TYPE(aType)) {
 699       Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_NEGATIVE_HIT);
 700     }
 701     aStatus = NS_ERROR_UNKNOWN_HOST;
 702   }
 703
 704   return result.forget();
 705 }
 706
 707 already_AddRefed<nsHostRecord> nsHostResolver::FromCachedIPLiteral(
 708     nsHostRecord* aRec) {
 709   Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_LITERAL);
 710   RefPtr<nsHostRecord> result = aRec;
 711   return result.forget();
 712 }
 713
 714 already_AddRefed<nsHostRecord> nsHostResolver::FromIPLiteral(
 715     AddrHostRecord* aAddrRec, const NetAddr& aAddr) {
 716   // ok, just copy the result into the host record, and be
 717   // done with it! ;-)
 718   aAddrRec->addr = MakeUnique<NetAddr>(aAddr);
 719   Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_LITERAL);
 720   // put reference to host record on stack...
 721   RefPtr<nsHostRecord> result = aAddrRec;
 722   return result.forget();
 723 }
 724
 725 already_AddRefed<nsHostRecord> nsHostResolver::FromUnspecEntry(
 726     nsHostRecord* aRec, const nsACString& aHost, const nsACString& aTrrServer,
 727     const nsACString& aOriginSuffix, uint16_t aType,
 728     nsIDNSService::DNSFlags aFlags, uint16_t af, bool aPb, nsresult& aStatus) {
 729   RefPtr<nsHostRecord> result = nullptr;
 730   // If this is an IPV4 or IPV6 specific request, check if there is
 731   // an AF_UNSPEC entry we can use. Otherwise, hit the resolver...
 732   RefPtr<AddrHostRecord> addrRec = do_QueryObject(aRec);
 733   if (addrRec && !(aFlags & RES_BYPASS_CACHE) &&
 734       ((af == PR_AF_INET) || (af == PR_AF_INET6))) {
 735     // Check for an AF_UNSPEC entry.
 736
 737     const nsHostKey unspecKey(aHost, aTrrServer,
 738                               nsIDNSService::RESOLVE_TYPE_DEFAULT, aFlags,
 739                               PR_AF_UNSPEC, aPb, aOriginSuffix);
 740     RefPtr<nsHostRecord> unspecRec = mRecordDB.Get(unspecKey);
 741
 742     TimeStamp now = TimeStamp::NowLoRes();
 743     if (unspecRec && unspecRec->HasUsableResult(now, aFlags)) {
 744       MOZ_ASSERT(unspecRec->IsAddrRecord());
 745
 746       RefPtr<AddrHostRecord> addrUnspecRec = do_QueryObject(unspecRec);
 747       MOZ_ASSERT(addrUnspecRec);
 748       MOZ_ASSERT(addrUnspecRec->addr_info || addrUnspecRec->negative,
 749                  "Entry should be resolved or negative.");
 750
 751       LOG(("  Trying AF_UNSPEC entry for host [%s] af: %s.\n",
 752            PromiseFlatCString(aHost).get(),
 753            (af == PR_AF_INET) ? "AF_INET" : "AF_INET6"));
 754
 755       // We need to lock in case any other thread is reading
 756       // addr_info.
 757       MutexAutoLock lock(addrRec->addr_info_lock);
 758
 759       addrRec->addr_info = nullptr;
 760       addrRec->addr_info_gencnt++;
 761       if (unspecRec->negative) {
 762         aRec->negative = unspecRec->negative;
 763         aRec->CopyExpirationTimesAndFlagsFrom(unspecRec);
 764       } else if (addrUnspecRec->addr_info) {
 765         MutexAutoLock lock(addrUnspecRec->addr_info_lock);
 766         if (addrUnspecRec->addr_info) {
 767           // Search for any valid address in the AF_UNSPEC entry
 768           // in the cache (not blocklisted and from the right
 769           // family).
 770           nsTArray<NetAddr> addresses;
 771           for (const auto& addr : addrUnspecRec->addr_info->Addresses()) {
 772             if ((af == addr.inet.family) &&
 773                 !addrUnspecRec->Blocklisted(&addr)) {
 774               addresses.AppendElement(addr);
 775             }
 776           }
 777           if (!addresses.IsEmpty()) {
 778             addrRec->addr_info = new AddrInfo(
 779                 addrUnspecRec->addr_info->Hostname(),
 780                 addrUnspecRec->addr_info->CanonicalHostname(),
 781                 addrUnspecRec->addr_info->ResolverType(),
 782                 addrUnspecRec->addr_info->TRRType(), std::move(addresses));
 783             addrRec->addr_info_gencnt++;
 784             aRec->CopyExpirationTimesAndFlagsFrom(unspecRec);
 785           }
 786         }
 787       }
 788       // Now check if we have a new record.
 789       if (aRec->HasUsableResult(now, aFlags)) {
 790         result = aRec;
 791         if (aRec->negative) {
 792           aStatus = NS_ERROR_UNKNOWN_HOST;
 793         }
 794         Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_HIT);
 795         ConditionallyRefreshRecord(aRec, aHost, lock);
 796       } else if (af == PR_AF_INET6) {
 797         // For AF_INET6, a new lookup means another AF_UNSPEC
 798         // lookup. We have already iterated through the
 799         // AF_UNSPEC addresses, so we mark this record as
 800         // negative.
 801         LOG(
 802             ("  No AF_INET6 in AF_UNSPEC entry: "
 803              "host [%s] unknown host.",
 804              nsPromiseFlatCString(aHost).get()));
 805         result = aRec;
 806         aRec->negative = true;
 807         aStatus = NS_ERROR_UNKNOWN_HOST;
 808         Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2,
 809                               METHOD_NEGATIVE_HIT);
 810       }
 811     }
 812   }
 813
 814   return result.forget();
 815 }
 816
 817 void nsHostResolver::DetachCallback(
 818     const nsACString& host, const nsACString& aTrrServer, uint16_t aType,
 819     const OriginAttributes& aOriginAttributes, nsIDNSService::DNSFlags flags,
 820     uint16_t af, nsResolveHostCallback* aCallback, nsresult status) {
 821   RefPtr<nsHostRecord> rec;
 822   RefPtr<nsResolveHostCallback> callback(aCallback);
 823
 824   {
 825     MutexAutoLock lock(mLock);
 826
 827     nsAutoCString originSuffix;
 828     aOriginAttributes.CreateSuffix(originSuffix);
 829
 830     nsHostKey key(host, aTrrServer, aType, flags, af,
 831                   (aOriginAttributes.mPrivateBrowsingId > 0), originSuffix);
 832     RefPtr<nsHostRecord> entry = mRecordDB.Get(key);
 833     if (entry) {
 834       // walk list looking for |callback|... we cannot assume
 835       // that it will be there!
 836
 837       for (nsResolveHostCallback* c : entry->mCallbacks) {
 838         if (c == callback) {
 839           rec = entry;
 840           c->remove();
 841           break;
 842         }
 843       }
 844     }
 845   }
 846
 847   // complete callback with the given status code; this would only be done if
 848   // the record was in the process of being resolved.
 849   if (rec) {
 850     callback->OnResolveHostComplete(this, rec, status);
 851   }
 852 }
 853
 854 nsresult nsHostResolver::ConditionallyCreateThread(nsHostRecord* rec) {
 855   if (mNumIdleTasks) {
 856     // wake up idle tasks to process this lookup
 857     mIdleTaskCV.Notify();
 858   } else if ((mActiveTaskCount < MaxResolverThreadsAnyPriority()) ||
 859              (IsHighPriority(rec->flags) &&
 860               mActiveTaskCount < MaxResolverThreads())) {
 861     nsCOMPtr<nsIRunnable> event = mozilla::NewRunnableMethod(
 862         "nsHostResolver::ThreadFunc", this, &nsHostResolver::ThreadFunc);
 863     mActiveTaskCount++;
 864     nsresult rv =
 865         mResolverThreads->Dispatch(event, nsIEventTarget::DISPATCH_NORMAL);
 866     if (NS_FAILED(rv)) {
 867       mActiveTaskCount--;
 868     }
 869   } else {
 870     LOG(("  Unable to find a thread for looking up host [%s].\n",
 871          rec->host.get()));
 872   }
 873   return NS_OK;
 874 }
 875
 876 nsresult nsHostResolver::TrrLookup_unlocked(nsHostRecord* rec, TRR* pushedTRR) {
 877   MutexAutoLock lock(mLock);
 878   return TrrLookup(rec, lock, pushedTRR);
 879 }
 880
 881 void nsHostResolver::MaybeRenewHostRecord(nsHostRecord* aRec) {
 882   MutexAutoLock lock(mLock);
 883   MaybeRenewHostRecordLocked(aRec, lock);
 884 }
 885
 886 void nsHostResolver::MaybeRenewHostRecordLocked(nsHostRecord* aRec,
 887                                                 const MutexAutoLock& aLock) {
 888   mQueue.MaybeRenewHostRecord(aRec, aLock);
 889 }
 890
 891 bool nsHostResolver::TRRServiceEnabledForRecord(nsHostRecord* aRec) {
 892   MOZ_ASSERT(aRec, "Record must not be empty");
 893   MOZ_ASSERT(aRec->mEffectiveTRRMode != nsIRequest::TRR_DEFAULT_MODE,
 894              "effective TRR mode must be computed before this call");
 895   if (!TRRService::Get()) {
 896     aRec->RecordReason(TRRSkippedReason::TRR_NO_GSERVICE);
 897     return false;
 898   }
 899
 900   // We always try custom resolvers.
 901   if (!aRec->mTrrServer.IsEmpty()) {
 902     return true;
 903   }
 904
 905   nsIRequest::TRRMode reqMode = aRec->mEffectiveTRRMode;
 906   if (TRRService::Get()->Enabled(reqMode)) {
 907     return true;
 908   }
 909
 910   if (NS_IsOffline()) {
 911     // If we are in the NOT_CONFIRMED state _because_ we lack connectivity,
 912     // then we should report that the browser is offline instead.
 913     aRec->RecordReason(TRRSkippedReason::TRR_IS_OFFLINE);
 914     return false;
 915   }
 916
 917   auto hasConnectivity = [this]() -> bool {
 918     mLock.AssertCurrentThreadOwns();
 919     if (!mNCS) {
 920       return true;
 921     }
 922     nsINetworkConnectivityService::ConnectivityState ipv4 = mNCS->GetIPv4();
 923     nsINetworkConnectivityService::ConnectivityState ipv6 = mNCS->GetIPv6();
 924
 925     if (ipv4 == nsINetworkConnectivityService::OK ||
 926         ipv6 == nsINetworkConnectivityService::OK) {
 927       return true;
 928     }
 929
 930     if (ipv4 == nsINetworkConnectivityService::UNKNOWN ||
 931         ipv6 == nsINetworkConnectivityService::UNKNOWN) {
 932       // One of the checks hasn't completed yet. Optimistically assume we'll
 933       // have network connectivity.
 934       return true;
 935     }
 936
 937     return false;
 938   };
 939
 940   if (!hasConnectivity()) {
 941     aRec->RecordReason(TRRSkippedReason::TRR_NO_CONNECTIVITY);
 942     return false;
 943   }
 944
 945   bool isConfirmed = TRRService::Get()->IsConfirmed();
 946   if (!isConfirmed) {
 947     aRec->RecordReason(TRRSkippedReason::TRR_NOT_CONFIRMED);
 948   }
 949
 950   return isConfirmed;
 951 }
 952
 953 // returns error if no TRR resolve is issued
 954 // it is impt this is not called while a native lookup is going on
 955 nsresult nsHostResolver::TrrLookup(nsHostRecord* aRec,
 956                                    const MutexAutoLock& aLock, TRR* pushedTRR) {
 957   if (Mode() == nsIDNSService::MODE_TRROFF ||
 958       StaticPrefs::network_dns_disabled()) {
 959     return NS_ERROR_UNKNOWN_HOST;
 960   }
 961   LOG(("TrrLookup host:%s af:%" PRId16, aRec->host.get(), aRec->af));
 962
 963   RefPtr<nsHostRecord> rec(aRec);
 964   mLock.AssertCurrentThreadOwns();
 965
 966   RefPtr<AddrHostRecord> addrRec;
 967   RefPtr<TypeHostRecord> typeRec;
 968
 969   if (rec->IsAddrRecord()) {
 970     addrRec = do_QueryObject(rec);
 971     MOZ_ASSERT(addrRec);
 972   } else {
 973     typeRec = do_QueryObject(rec);
 974     MOZ_ASSERT(typeRec);
 975   }
 976
 977   MOZ_ASSERT(!rec->mResolving);
 978
 979   if (!TRRServiceEnabledForRecord(aRec)) {
 980     return NS_ERROR_UNKNOWN_HOST;
 981   }
 982
 983   MaybeRenewHostRecordLocked(rec, aLock);
 984
 985   RefPtr<TRRQuery> query = new TRRQuery(this, rec);
 986   nsresult rv = query->DispatchLookup(pushedTRR);
 987   if (NS_FAILED(rv)) {
 988     rec->RecordReason(TRRSkippedReason::TRR_DID_NOT_MAKE_QUERY);
 989     return rv;
 990   }
 991
 992   {
 993     auto lock = rec->mTRRQuery.Lock();
 994     MOZ_ASSERT(!lock.ref(), "TRR already in progress");
 995     lock.ref() = query;
 996   }
 997
 998   rec->mResolving++;
 999   rec->mTrrAttempts++;
1000   rec->StoreNative(false);
1001   return NS_OK;
1002 }
1003
1004 nsresult nsHostResolver::NativeLookup(nsHostRecord* aRec,
1005                                       const MutexAutoLock& aLock) {
1006   if (StaticPrefs::network_dns_disabled()) {
1007     return NS_ERROR_UNKNOWN_HOST;
1008   }
1009   LOG(("NativeLookup host:%s af:%" PRId16, aRec->host.get(), aRec->af));
1010
1011   // If this is not a A/AAAA request, make sure native HTTPS is enabled.
1012   MOZ_ASSERT(aRec->IsAddrRecord() || IsNativeHTTPSEnabled());
1013   mLock.AssertCurrentThreadOwns();
1014
1015   RefPtr<nsHostRecord> rec(aRec);
1016
1017   rec->mNativeStart = TimeStamp::Now();
1018
1019   // Add rec to one of the pending queues, possibly removing it from mEvictionQ.
1020   MaybeRenewHostRecordLocked(aRec, aLock);
1021
1022   mQueue.InsertRecord(rec, rec->flags, aLock);
1023
1024   rec->StoreNative(true);
1025   rec->StoreNativeUsed(true);
1026   rec->mResolving++;
1027
1028   nsresult rv = ConditionallyCreateThread(rec);
1029
1030   LOG(("  DNS thread counters: total=%d any-live=%d idle=%d pending=%d\n",
1031        static_cast<uint32_t>(mActiveTaskCount),
1032        static_cast<uint32_t>(mActiveAnyThreadCount),
1033        static_cast<uint32_t>(mNumIdleTasks), mQueue.PendingCount()));
1034
1035   return rv;
1036 }
1037
1038 // static
1039 nsIDNSService::ResolverMode nsHostResolver::Mode() {
1040   if (TRRService::Get()) {
1041     return TRRService::Get()->Mode();
1042   }
1043
1044   // If we don't have a TRR service just return MODE_TRROFF so we don't make
1045   // any TRR requests by mistake.
1046   return nsIDNSService::MODE_TRROFF;
1047 }
1048
1049 nsIRequest::TRRMode nsHostRecord::TRRMode() {
1050   return nsIDNSService::GetTRRModeFromFlags(flags);
1051 }
1052
1053 // static
1054 void nsHostResolver::ComputeEffectiveTRRMode(nsHostRecord* aRec) {
1055   nsIDNSService::ResolverMode resolverMode = nsHostResolver::Mode();
1056   nsIRequest::TRRMode requestMode = aRec->TRRMode();
1057
1058   // For domains that are excluded from TRR or when parental control is enabled,
1059   // we fallback to NativeLookup. This happens even in MODE_TRRONLY. By default
1060   // localhost and local are excluded (so we cover *.local hosts) See the
1061   // network.trr.excluded-domains pref.
1062
1063   if (!TRRService::Get()) {
1064     aRec->RecordReason(TRRSkippedReason::TRR_NO_GSERVICE);
1065     aRec->mEffectiveTRRMode = requestMode;
1066     return;
1067   }
1068
1069   if (!aRec->mTrrServer.IsEmpty()) {
1070     aRec->mEffectiveTRRMode = nsIRequest::TRR_ONLY_MODE;
1071     return;
1072   }
1073
1074   if (TRRService::Get()->IsExcludedFromTRR(aRec->host)) {
1075     aRec->RecordReason(TRRSkippedReason::TRR_EXCLUDED);
1076     aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1077     return;
1078   }
1079
1080   if (TRRService::Get()->ParentalControlEnabled()) {
1081     aRec->RecordReason(TRRSkippedReason::TRR_PARENTAL_CONTROL);
1082     aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1083     return;
1084   }
1085
1086   if (resolverMode == nsIDNSService::MODE_TRROFF) {
1087     aRec->RecordReason(TRRSkippedReason::TRR_OFF_EXPLICIT);
1088     aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1089     return;
1090   }
1091
1092   if (requestMode == nsIRequest::TRR_DISABLED_MODE) {
1093     aRec->RecordReason(TRRSkippedReason::TRR_REQ_MODE_DISABLED);
1094     aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1095     return;
1096   }
1097
1098   if ((requestMode == nsIRequest::TRR_DEFAULT_MODE &&
1099        resolverMode == nsIDNSService::MODE_NATIVEONLY)) {
1100     if (StaticPrefs::network_trr_display_fallback_warning()) {
1101       TRRSkippedReason heuristicResult =
1102           TRRService::Get()->GetHeuristicDetectionResult();
1103       if (heuristicResult != TRRSkippedReason::TRR_UNSET &&
1104           heuristicResult != TRRSkippedReason::TRR_OK) {
1105         aRec->RecordReason(heuristicResult);
1106         aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1107         return;
1108       }
1109     }
1110     aRec->RecordReason(TRRSkippedReason::TRR_MODE_NOT_ENABLED);
1111     aRec->mEffectiveTRRMode = nsIRequest::TRR_DISABLED_MODE;
1112     return;
1113   }
1114
1115   if (requestMode == nsIRequest::TRR_DEFAULT_MODE &&
1116       resolverMode == nsIDNSService::MODE_TRRFIRST) {
1117     aRec->mEffectiveTRRMode = nsIRequest::TRR_FIRST_MODE;
1118     return;
1119   }
1120
1121   if (requestMode == nsIRequest::TRR_DEFAULT_MODE &&
1122       resolverMode == nsIDNSService::MODE_TRRONLY) {
1123     aRec->mEffectiveTRRMode = nsIRequest::TRR_ONLY_MODE;
1124     return;
1125   }
1126
1127   aRec->mEffectiveTRRMode = requestMode;
1128 }
1129
1130 // Kick-off a name resolve operation, using native resolver and/or TRR
1131 nsresult nsHostResolver::NameLookup(nsHostRecord* rec,
1132                                     const mozilla::MutexAutoLock& aLock) {
1133   LOG(("NameLookup host:%s af:%" PRId16, rec->host.get(), rec->af));
1134   mLock.AssertCurrentThreadOwns();
1135
1136   if (rec->flags & RES_IP_HINT) {
1137     LOG(("Skip lookup if RES_IP_HINT is set\n"));
1138     return NS_ERROR_UNKNOWN_HOST;
1139   }
1140
1141   nsresult rv = NS_ERROR_UNKNOWN_HOST;
1142   if (rec->mResolving) {
1143     LOG(("NameLookup %s while already resolving\n", rec->host.get()));
1144     return NS_OK;
1145   }
1146
1147   // Make sure we reset the reason each time we attempt to do a new lookup
1148   // so we don't wrongly report the reason for the previous one.
1149   rec->Reset();
1150
1151   ComputeEffectiveTRRMode(rec);
1152
1153   if (!rec->mTrrServer.IsEmpty()) {
1154     LOG(("NameLookup: %s use trr:%s", rec->host.get(), rec->mTrrServer.get()));
1155     if (rec->mEffectiveTRRMode != nsIRequest::TRR_ONLY_MODE) {
1156       return NS_ERROR_UNKNOWN_HOST;
1157     }
1158
1159     if (rec->flags & nsIDNSService::RESOLVE_DISABLE_TRR) {
1160       LOG(("TRR with server and DISABLE_TRR flag. Returning error."));
1161       return NS_ERROR_UNKNOWN_HOST;
1162     }
1163     return TrrLookup(rec, aLock);
1164   }
1165
1166   LOG(("NameLookup: %s effectiveTRRmode: %d flags: %X", rec->host.get(),
1167        static_cast<nsIRequest::TRRMode>(rec->mEffectiveTRRMode), rec->flags));
1168
1169   if (rec->flags & nsIDNSService::RESOLVE_DISABLE_TRR) {
1170     rec->RecordReason(TRRSkippedReason::TRR_DISABLED_FLAG);
1171   }
1172
1173   bool serviceNotReady = !TRRServiceEnabledForRecord(rec);
1174
1175   if (rec->mEffectiveTRRMode != nsIRequest::TRR_DISABLED_MODE &&
1176       !((rec->flags & nsIDNSService::RESOLVE_DISABLE_TRR)) &&
1177       !serviceNotReady) {
1178     rv = TrrLookup(rec, aLock);
1179   }
1180
1181   if (rec->mEffectiveTRRMode == nsIRequest::TRR_DISABLED_MODE ||
1182       (rec->mEffectiveTRRMode == nsIRequest::TRR_FIRST_MODE &&
1183        (rec->flags & nsIDNSService::RESOLVE_DISABLE_TRR || serviceNotReady ||
1184         NS_FAILED(rv)))) {
1185     if (!IsNativeHTTPSEnabled() && !rec->IsAddrRecord()) {
1186       return rv;
1187     }
1188
1189 #ifdef DEBUG
1190     // If we use this branch then the mTRRUsed flag should not be set
1191     // Even if we did call TrrLookup above, the fact that it failed sync-ly
1192     // means that we didn't actually succeed in opening the channel.
1193     RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
1194     MOZ_ASSERT_IF(addrRec, addrRec->mResolverType == DNSResolverType::Native);
1195 #endif
1196
1197     // We did not lookup via TRR - don't fallback to native if the
1198     // network.trr.display_fallback_warning pref is set and either
1199     // 1. we are in TRR first mode and confirmation failed
1200     // 2. the record has trr_disabled and a heuristic skip reason
1201     if (StaticPrefs::network_trr_display_fallback_warning() &&
1202         rec->mEffectiveTRRMode != nsIRequest::TRR_ONLY_MODE) {
1203       if ((rec->mEffectiveTRRMode == nsIRequest::TRR_FIRST_MODE &&
1204            rec->mTRRSkippedReason == TRRSkippedReason::TRR_NOT_CONFIRMED) ||
1205           (rec->mEffectiveTRRMode == nsIRequest::TRR_DISABLED_MODE &&
1206            rec->mTRRSkippedReason >=
1207                nsITRRSkipReason::TRR_HEURISTIC_TRIPPED_GOOGLE_SAFESEARCH &&
1208            rec->mTRRSkippedReason <=
1209                nsITRRSkipReason::TRR_HEURISTIC_TRIPPED_NRPT)) {
1210         LOG((
1211             "NameLookup: ResolveHostComplete with status NS_ERROR_UNKNOWN_HOST "
1212             "for: %s effectiveTRRmode: "
1213             "%d SkippedReason: %d",
1214             rec->host.get(),
1215             static_cast<nsIRequest::TRRMode>(rec->mEffectiveTRRMode),
1216             static_cast<int32_t>(rec->mTRRSkippedReason)));
1217
1218         mozilla::LinkedList<RefPtr<nsResolveHostCallback>> cbs =
1219             std::move(rec->mCallbacks);
1220         for (nsResolveHostCallback* c = cbs.getFirst(); c;
1221              c = c->removeAndGetNext()) {
1222           c->OnResolveHostComplete(this, rec, NS_ERROR_UNKNOWN_HOST);
1223         }
1224
1225         return NS_OK;
1226       }
1227     }
1228
1229     rv = NativeLookup(rec, aLock);
1230   }
1231
1232   return rv;
1233 }
1234
1235 nsresult nsHostResolver::ConditionallyRefreshRecord(
1236     nsHostRecord* rec, const nsACString& host, const MutexAutoLock& aLock) {
1237   if ((rec->CheckExpiration(TimeStamp::NowLoRes()) != nsHostRecord::EXP_VALID ||
1238        rec->negative) &&
1239       !rec->mResolving && rec->RefreshForNegativeResponse()) {
1240     LOG(("  Using %s cache entry for host [%s] but starting async renewal.",
1241          rec->negative ? "negative" : "positive", host.BeginReading()));
1242     NameLookup(rec, aLock);
1243
1244     if (rec->IsAddrRecord() && !rec->negative) {
1245       // negative entries are constantly being refreshed, only
1246       // track positive grace period induced renewals
1247       Telemetry::Accumulate(Telemetry::DNS_LOOKUP_METHOD2, METHOD_RENEWAL);
1248     }
1249   }
1250   return NS_OK;
1251 }
1252
1253 bool nsHostResolver::GetHostToLookup(nsHostRecord** result) {
1254   bool timedOut = false;
1255   TimeDuration timeout;
1256   TimeStamp epoch, now;
1257
1258   MutexAutoLock lock(mLock);
1259
1260   timeout = (mNumIdleTasks >= MaxResolverThreadsAnyPriority())
1261                 ? mShortIdleTimeout
1262                 : mLongIdleTimeout;
1263   epoch = TimeStamp::Now();
1264
1265   while (!mShutdown) {
1266     // remove next record from Q; hand over owning reference. Check high, then
1267     // med, then low
1268
1269 #define SET_GET_TTL(var, val) (var)->StoreGetTtl(sGetTtlEnabled && (val))
1270
1271     RefPtr<nsHostRecord> rec = mQueue.Dequeue(true, lock);
1272     if (rec) {
1273       SET_GET_TTL(rec, false);
1274       rec.forget(result);
1275       return true;
1276     }
1277
1278     if (mActiveAnyThreadCount < MaxResolverThreadsAnyPriority()) {
1279       rec = mQueue.Dequeue(false, lock);
1280       if (rec) {
1281         MOZ_ASSERT(IsMediumPriority(rec->flags) || IsLowPriority(rec->flags));
1282         mActiveAnyThreadCount++;
1283         rec->StoreUsingAnyThread(true);
1284         SET_GET_TTL(rec, true);
1285         rec.forget(result);
1286         return true;
1287       }
1288     }
1289
1290     // Determining timeout is racy, so allow one cycle through checking the
1291     // queues before exiting.
1292     if (timedOut) {
1293       break;
1294     }
1295
1296     // wait for one or more of the following to occur:
1297     //  (1) the pending queue has a host record to process
1298     //  (2) the shutdown flag has been set
1299     //  (3) the thread has been idle for too long
1300
1301     mNumIdleTasks++;
1302     mIdleTaskCV.Wait(timeout);
1303     mNumIdleTasks--;
1304
1305     now = TimeStamp::Now();
1306
1307     if (now - epoch >= timeout) {
1308       timedOut = true;
1309     } else {
1310       // It is possible that CondVar::Wait() was interrupted and returned
1311       // early, in which case we will loop back and re-enter it. In that
1312       // case we want to do so with the new timeout reduced to reflect
1313       // time already spent waiting.
1314       timeout -= now - epoch;
1315       epoch = now;
1316     }
1317   }
1318
1319   // tell thread to exit...
1320   return false;
1321 }
1322
1323 void nsHostResolver::PrepareRecordExpirationAddrRecord(
1324     AddrHostRecord* rec) const {
1325   // NOTE: rec->addr_info_lock is already held by parent
1326   MOZ_ASSERT(((bool)rec->addr_info) != rec->negative);
1327   mLock.AssertCurrentThreadOwns();
1328   if (!rec->addr_info) {
1329     rec->SetExpiration(TimeStamp::NowLoRes(), NEGATIVE_RECORD_LIFETIME, 0);
1330     LOG(("Caching host [%s] negative record for %u seconds.\n", rec->host.get(),
1331          NEGATIVE_RECORD_LIFETIME));
1332     return;
1333   }
1334
1335   unsigned int lifetime = mDefaultCacheLifetime;
1336   unsigned int grace = mDefaultGracePeriod;
1337
1338   unsigned int ttl = mDefaultCacheLifetime;
1339   if (sGetTtlEnabled || rec->addr_info->IsTRR()) {
1340     if (rec->addr_info && rec->addr_info->TTL() != AddrInfo::NO_TTL_DATA) {
1341       ttl = rec->addr_info->TTL();
1342     }
1343     lifetime = ttl;
1344     grace = 0;
1345   }
1346
1347   rec->SetExpiration(TimeStamp::NowLoRes(), lifetime, grace);
1348   LOG(("Caching host [%s] record for %u seconds (grace %d).", rec->host.get(),
1349        lifetime, grace));
1350 }
1351
1352 static bool different_rrset(AddrInfo* rrset1, AddrInfo* rrset2) {
1353   if (!rrset1 || !rrset2) {
1354     return true;
1355   }
1356
1357   LOG(("different_rrset %s\n", rrset1->Hostname().get()));
1358
1359   if (rrset1->ResolverType() != rrset2->ResolverType()) {
1360     return true;
1361   }
1362
1363   if (rrset1->TRRType() != rrset2->TRRType()) {
1364     return true;
1365   }
1366
1367   if (rrset1->Addresses().Length() != rrset2->Addresses().Length()) {
1368     LOG(("different_rrset true due to length change\n"));
1369     return true;
1370   }
1371
1372   nsTArray<NetAddr> orderedSet1 = rrset1->Addresses().Clone();
1373   nsTArray<NetAddr> orderedSet2 = rrset2->Addresses().Clone();
1374   orderedSet1.Sort();
1375   orderedSet2.Sort();
1376
1377   bool eq = orderedSet1 == orderedSet2;
1378   if (!eq) {
1379     LOG(("different_rrset true due to content change\n"));
1380   } else {
1381     LOG(("different_rrset false\n"));
1382   }
1383   return !eq;
1384 }
1385
1386 void nsHostResolver::AddToEvictionQ(nsHostRecord* rec,
1387                                     const MutexAutoLock& aLock) {
1388   mQueue.AddToEvictionQ(rec, mMaxCacheEntries, mRecordDB, aLock);
1389 }
1390
1391 // After a first lookup attempt with TRR in mode 2, we may:
1392 // - If network.trr.retry_on_recoverable_errors is false, retry with native.
1393 // - If network.trr.retry_on_recoverable_errors is true:
1394 //   - Retry with native if the first attempt failed because we got NXDOMAIN, an
1395 //     unreachable address (TRR_DISABLED_FLAG), or we skipped TRR because
1396 //     Confirmation failed.
1397 //   - Trigger a "RetryTRR" Confirmation which will start a fresh
1398 //     connection for TRR, and then retry the lookup with TRR.
1399 //   - If the second attempt failed, fallback to native if
1400 //     network.trr.strict_native_fallback is false.
1401 // Returns true if we retried with either TRR or Native.
1402 bool nsHostResolver::MaybeRetryTRRLookup(
1403     AddrHostRecord* aAddrRec, nsresult aFirstAttemptStatus,
1404     TRRSkippedReason aFirstAttemptSkipReason, nsresult aChannelStatus,
1405     const MutexAutoLock& aLock) {
1406   if (NS_FAILED(aFirstAttemptStatus) &&
1407       (aChannelStatus == NS_ERROR_PROXY_UNAUTHORIZED ||
1408        aChannelStatus == NS_ERROR_PROXY_AUTHENTICATION_FAILED) &&
1409       aAddrRec->mEffectiveTRRMode == nsIRequest::TRR_ONLY_MODE) {
1410     LOG(("MaybeRetryTRRLookup retry because of proxy connect failed"));
1411     TRRService::Get()->DontUseTRRThread();
1412     return DoRetryTRR(aAddrRec, aLock);
1413   }
1414
1415   if (NS_SUCCEEDED(aFirstAttemptStatus) ||
1416       aAddrRec->mEffectiveTRRMode != nsIRequest::TRR_FIRST_MODE ||
1417       aFirstAttemptStatus == NS_ERROR_DEFINITIVE_UNKNOWN_HOST) {
1418     return false;
1419   }
1420
1421   MOZ_ASSERT(!aAddrRec->mResolving);
1422   if (!StaticPrefs::network_trr_retry_on_recoverable_errors()) {
1423     LOG(("nsHostResolver::MaybeRetryTRRLookup retrying with native"));
1424     return NS_SUCCEEDED(NativeLookup(aAddrRec, aLock));
1425   }
1426
1427   if (IsFailedConfirmationOrNoConnectivity(aFirstAttemptSkipReason) ||
1428       IsNonRecoverableTRRSkipReason(aFirstAttemptSkipReason) ||
1429       IsBlockedTRRRequest(aFirstAttemptSkipReason)) {
1430     LOG(
1431         ("nsHostResolver::MaybeRetryTRRLookup retrying with native in strict "
1432          "mode, skip reason was %d",
1433          static_cast<uint32_t>(aFirstAttemptSkipReason)));
1434     return NS_SUCCEEDED(NativeLookup(aAddrRec, aLock));
1435   }
1436
1437   if (aAddrRec->mTrrAttempts > 1) {
1438     if (!StaticPrefs::network_trr_strict_native_fallback()) {
1439       LOG(
1440           ("nsHostResolver::MaybeRetryTRRLookup retry failed. Using "
1441            "native."));
1442       return NS_SUCCEEDED(NativeLookup(aAddrRec, aLock));
1443     }
1444
1445     if (aFirstAttemptSkipReason == TRRSkippedReason::TRR_TIMEOUT &&
1446         StaticPrefs::network_trr_strict_native_fallback_allow_timeouts()) {
1447       LOG(
1448           ("nsHostResolver::MaybeRetryTRRLookup retry timed out. Using "
1449            "native."));
1450       return NS_SUCCEEDED(NativeLookup(aAddrRec, aLock));
1451     }
1452     LOG(("nsHostResolver::MaybeRetryTRRLookup mTrrAttempts>1, not retrying."));
1453     return false;
1454   }
1455
1456   LOG(
1457       ("nsHostResolver::MaybeRetryTRRLookup triggering Confirmation and "
1458        "retrying with TRR, skip reason was %d",
1459        static_cast<uint32_t>(aFirstAttemptSkipReason)));
1460   TRRService::Get()->RetryTRRConfirm();
1461
1462   return DoRetryTRR(aAddrRec, aLock);
1463 }
1464
1465 bool nsHostResolver::DoRetryTRR(AddrHostRecord* aAddrRec,
1466                                 const mozilla::MutexAutoLock& aLock) {
1467   {
1468     // Clear out the old query
1469     auto trrQuery = aAddrRec->mTRRQuery.Lock();
1470     trrQuery.ref() = nullptr;
1471   }
1472
1473   if (NS_SUCCEEDED(TrrLookup(aAddrRec, aLock, nullptr /* pushedTRR */))) {
1474     aAddrRec->NotifyRetryingTrr();
1475     return true;
1476   }
1477
1478   return false;
1479 }
1480
1481 //
1482 // CompleteLookup() checks if the resolving should be redone and if so it
1483 // returns LOOKUP_RESOLVEAGAIN, but only if 'status' is not NS_ERROR_ABORT.
1484 nsHostResolver::LookupStatus nsHostResolver::CompleteLookup(
1485     nsHostRecord* rec, nsresult status, AddrInfo* aNewRRSet, bool pb,
1486     const nsACString& aOriginsuffix, TRRSkippedReason aReason,
1487     mozilla::net::TRR* aTRRRequest) {
1488   MutexAutoLock lock(mLock);
1489   return CompleteLookupLocked(rec, status, aNewRRSet, pb, aOriginsuffix,
1490                               aReason, aTRRRequest, lock);
1491 }
1492
1493 nsHostResolver::LookupStatus nsHostResolver::CompleteLookupLocked(
1494     nsHostRecord* rec, nsresult status, AddrInfo* aNewRRSet, bool pb,
1495     const nsACString& aOriginsuffix, TRRSkippedReason aReason,
1496     mozilla::net::TRR* aTRRRequest, const mozilla::MutexAutoLock& aLock) {
1497   MOZ_ASSERT(rec);
1498   MOZ_ASSERT(rec->pb == pb);
1499   MOZ_ASSERT(rec->IsAddrRecord());
1500
1501   RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
1502   MOZ_ASSERT(addrRec);
1503
1504   RefPtr<AddrInfo> newRRSet(aNewRRSet);
1505   MOZ_ASSERT(NS_FAILED(status) || newRRSet->Addresses().Length() > 0);
1506
1507   DNSResolverType type =
1508       newRRSet ? newRRSet->ResolverType() : DNSResolverType::Native;
1509
1510   if (NS_FAILED(status)) {
1511     newRRSet = nullptr;
1512   }
1513
1514   if (addrRec->LoadResolveAgain() && (status != NS_ERROR_ABORT) &&
1515       type == DNSResolverType::Native) {
1516     LOG(("nsHostResolver record %p resolve again due to flushcache\n",
1517          addrRec.get()));
1518     addrRec->StoreResolveAgain(false);
1519     return LOOKUP_RESOLVEAGAIN;
1520   }
1521
1522   MOZ_ASSERT(addrRec->mResolving);
1523   addrRec->mResolving--;
1524   LOG((
1525       "nsHostResolver::CompleteLookup %s %p %X resolver=%d stillResolving=%d\n",
1526       addrRec->host.get(), aNewRRSet, (unsigned int)status, (int)type,
1527       int(addrRec->mResolving)));
1528
1529   if (type != DNSResolverType::Native) {
1530     if (NS_FAILED(status) && status != NS_ERROR_UNKNOWN_HOST &&
1531         status != NS_ERROR_DEFINITIVE_UNKNOWN_HOST) {
1532       // the errors are not failed resolves, that means
1533       // something else failed, consider this as *TRR not used*
1534       // for actually trying to resolve the host
1535       addrRec->mResolverType = DNSResolverType::Native;
1536     }
1537
1538     if (NS_FAILED(status)) {
1539       if (aReason != TRRSkippedReason::TRR_UNSET) {
1540         addrRec->RecordReason(aReason);
1541       } else {
1542         // Unknown failed reason.
1543         addrRec->RecordReason(TRRSkippedReason::TRR_FAILED);
1544       }
1545     } else {
1546       addrRec->mTRRSuccess = true;
1547       addrRec->RecordReason(TRRSkippedReason::TRR_OK);
1548     }
1549
1550     nsresult channelStatus = aTRRRequest->ChannelStatus();
1551     if (MaybeRetryTRRLookup(addrRec, status, aReason, channelStatus, aLock)) {
1552       MOZ_ASSERT(addrRec->mResolving);
1553       return LOOKUP_OK;
1554     }
1555
1556     if (!addrRec->mTRRSuccess) {
1557       // no TRR success
1558       newRRSet = nullptr;
1559     }
1560
1561     if (NS_FAILED(status)) {
1562       // This is the error that consumers expect.
1563       status = NS_ERROR_UNKNOWN_HOST;
1564     }
1565   } else {  // native resolve completed
1566     if (addrRec->LoadUsingAnyThread()) {
1567       mActiveAnyThreadCount--;
1568       addrRec->StoreUsingAnyThread(false);
1569     }
1570
1571     addrRec->mNativeSuccess = static_cast<bool>(newRRSet);
1572     if (addrRec->mNativeSuccess) {
1573       addrRec->mNativeDuration = TimeStamp::Now() - addrRec->mNativeStart;
1574     }
1575   }
1576
1577   addrRec->OnCompleteLookup();
1578
1579   // update record fields.  We might have a addrRec->addr_info already if a
1580   // previous lookup result expired and we're reresolving it or we get
1581   // a late second TRR response.
1582   if (!mShutdown) {
1583     MutexAutoLock lock(addrRec->addr_info_lock);
1584     RefPtr<AddrInfo> old_addr_info;
1585     if (different_rrset(addrRec->addr_info, newRRSet)) {
1586       LOG(("nsHostResolver record %p new gencnt\n", addrRec.get()));
1587       old_addr_info = addrRec->addr_info;
1588       addrRec->addr_info = std::move(newRRSet);
1589       addrRec->addr_info_gencnt++;
1590     } else {
1591       if (addrRec->addr_info && newRRSet) {
1592         auto builder = addrRec->addr_info->Build();
1593         builder.SetTTL(newRRSet->TTL());
1594         // Update trr timings
1595         builder.SetTrrFetchDuration(newRRSet->GetTrrFetchDuration());
1596         builder.SetTrrFetchDurationNetworkOnly(
1597             newRRSet->GetTrrFetchDurationNetworkOnly());
1598
1599         addrRec->addr_info = builder.Finish();
1600       }
1601       old_addr_info = std::move(newRRSet);
1602     }
1603     addrRec->negative = !addrRec->addr_info;
1604     PrepareRecordExpirationAddrRecord(addrRec);
1605   }
1606
1607   if (LOG_ENABLED()) {
1608     MutexAutoLock lock(addrRec->addr_info_lock);
1609     if (addrRec->addr_info) {
1610       for (const auto& elem : addrRec->addr_info->Addresses()) {
1611         char buf[128];
1612         elem.ToStringBuffer(buf, sizeof(buf));
1613         LOG(("CompleteLookup: %s has %s\n", addrRec->host.get(), buf));
1614       }
1615     } else {
1616       LOG(("CompleteLookup: %s has NO address\n", addrRec->host.get()));
1617     }
1618   }
1619
1620   // get the list of pending callbacks for this lookup, and notify
1621   // them that the lookup is complete.
1622   mozilla::LinkedList<RefPtr<nsResolveHostCallback>> cbs =
1623       std::move(rec->mCallbacks);
1624
1625   LOG(("nsHostResolver record %p calling back dns users status:%X\n",
1626        addrRec.get(), int(status)));
1627
1628   for (nsResolveHostCallback* c = cbs.getFirst(); c;
1629        c = c->removeAndGetNext()) {
1630     c->OnResolveHostComplete(this, rec, status);
1631   }
1632
1633   OnResolveComplete(rec, aLock);
1634
1635 #ifdef DNSQUERY_AVAILABLE
1636   // Unless the result is from TRR, resolve again to get TTL
1637   bool hasNativeResult = false;
1638   {
1639     MutexAutoLock lock(addrRec->addr_info_lock);
1640     if (addrRec->addr_info && !addrRec->addr_info->IsTRR()) {
1641       hasNativeResult = true;
1642     }
1643   }
1644   if (hasNativeResult && !mShutdown && !addrRec->LoadGetTtl() &&
1645       !rec->mResolving && sGetTtlEnabled) {
1646     LOG(("Issuing second async lookup for TTL for host [%s].",
1647          addrRec->host.get()));
1648     addrRec->flags =
1649         (addrRec->flags & ~nsIDNSService::RESOLVE_PRIORITY_MEDIUM) |
1650         nsIDNSService::RESOLVE_PRIORITY_LOW;
1651     DebugOnly<nsresult> rv = NativeLookup(rec, aLock);
1652     NS_WARNING_ASSERTION(NS_SUCCEEDED(rv),
1653                          "Could not issue second async lookup for TTL.");
1654   }
1655 #endif
1656   return LOOKUP_OK;
1657 }
1658
1659 nsHostResolver::LookupStatus nsHostResolver::CompleteLookupByType(
1660     nsHostRecord* rec, nsresult status,
1661     mozilla::net::TypeRecordResultType& aResult, TRRSkippedReason aReason,
1662     uint32_t aTtl, bool pb) {
1663   MutexAutoLock lock(mLock);
1664   return CompleteLookupByTypeLocked(rec, status, aResult, aReason, aTtl, pb,
1665                                     lock);
1666 }
1667
1668 nsHostResolver::LookupStatus nsHostResolver::CompleteLookupByTypeLocked(
1669     nsHostRecord* rec, nsresult status,
1670     mozilla::net::TypeRecordResultType& aResult, TRRSkippedReason aReason,
1671     uint32_t aTtl, bool pb, const mozilla::MutexAutoLock& aLock) {
1672   MOZ_ASSERT(rec);
1673   MOZ_ASSERT(rec->pb == pb);
1674   MOZ_ASSERT(!rec->IsAddrRecord());
1675
1676   RefPtr<TypeHostRecord> typeRec = do_QueryObject(rec);
1677   MOZ_ASSERT(typeRec);
1678
1679   MOZ_ASSERT(typeRec->mResolving);
1680   typeRec->mResolving--;
1681
1682   if (NS_FAILED(status)) {
1683     LOG(("nsHostResolver::CompleteLookupByType record %p [%s] status %x\n",
1684          typeRec.get(), typeRec->host.get(), (unsigned int)status));
1685     typeRec->SetExpiration(
1686         TimeStamp::NowLoRes(),
1687         StaticPrefs::network_dns_negative_ttl_for_type_record(), 0);
1688     MOZ_ASSERT(aResult.is<TypeRecordEmpty>());
1689     status = NS_ERROR_UNKNOWN_HOST;
1690     typeRec->negative = true;
1691     if (aReason != TRRSkippedReason::TRR_UNSET) {
1692       typeRec->RecordReason(aReason);
1693     } else {
1694       // Unknown failed reason.
1695       typeRec->RecordReason(TRRSkippedReason::TRR_FAILED);
1696     }
1697   } else {
1698     size_t recordCount = 0;
1699     if (aResult.is<TypeRecordTxt>()) {
1700       recordCount = aResult.as<TypeRecordTxt>().Length();
1701     } else if (aResult.is<TypeRecordHTTPSSVC>()) {
1702       recordCount = aResult.as<TypeRecordHTTPSSVC>().Length();
1703     }
1704     LOG(
1705         ("nsHostResolver::CompleteLookupByType record %p [%s], number of "
1706          "records %zu\n",
1707          typeRec.get(), typeRec->host.get(), recordCount));
1708     MutexAutoLock typeLock(typeRec->mResultsLock);
1709     typeRec->mResults = aResult;
1710     typeRec->SetExpiration(TimeStamp::NowLoRes(), aTtl, mDefaultGracePeriod);
1711     typeRec->negative = false;
1712     typeRec->mTRRSuccess = !rec->LoadNative();
1713     typeRec->mNativeSuccess = rec->LoadNative();
1714     MOZ_ASSERT(aReason != TRRSkippedReason::TRR_UNSET);
1715     typeRec->RecordReason(aReason);
1716   }
1717
1718   mozilla::LinkedList<RefPtr<nsResolveHostCallback>> cbs =
1719       std::move(typeRec->mCallbacks);
1720
1721   LOG(
1722       ("nsHostResolver::CompleteLookupByType record %p calling back dns "
1723        "users\n",
1724        typeRec.get()));
1725
1726   for (nsResolveHostCallback* c = cbs.getFirst(); c;
1727        c = c->removeAndGetNext()) {
1728     c->OnResolveHostComplete(this, rec, status);
1729   }
1730
1731   OnResolveComplete(rec, aLock);
1732
1733   return LOOKUP_OK;
1734 }
1735
1736 void nsHostResolver::OnResolveComplete(nsHostRecord* aRec,
1737                                        const mozilla::MutexAutoLock& aLock) {
1738   if (!aRec->mResolving && !mShutdown) {
1739     {
1740       auto trrQuery = aRec->mTRRQuery.Lock();
1741       if (trrQuery.ref()) {
1742         aRec->mTrrDuration = trrQuery.ref()->Duration();
1743       }
1744       trrQuery.ref() = nullptr;
1745     }
1746     aRec->ResolveComplete();
1747
1748     AddToEvictionQ(aRec, aLock);
1749   }
1750 }
1751
1752 void nsHostResolver::CancelAsyncRequest(
1753     const nsACString& host, const nsACString& aTrrServer, uint16_t aType,
1754     const OriginAttributes& aOriginAttributes, nsIDNSService::DNSFlags flags,
1755     uint16_t af, nsIDNSListener* aListener, nsresult status)
1756
1757 {
1758   MutexAutoLock lock(mLock);
1759
1760   nsAutoCString originSuffix;
1761   aOriginAttributes.CreateSuffix(originSuffix);
1762
1763   // Lookup the host record associated with host, flags & address family
1764
1765   nsHostKey key(host, aTrrServer, aType, flags, af,
1766                 (aOriginAttributes.mPrivateBrowsingId > 0), originSuffix);
1767   RefPtr<nsHostRecord> rec = mRecordDB.Get(key);
1768   if (!rec) {
1769     return;
1770   }
1771
1772   for (RefPtr<nsResolveHostCallback> c : rec->mCallbacks) {
1773     if (c->EqualsAsyncListener(aListener)) {
1774       c->remove();
1775       c->OnResolveHostComplete(this, rec.get(), status);
1776       break;
1777     }
1778   }
1779
1780   // If there are no more callbacks, remove the hash table entry
1781   if (rec->mCallbacks.isEmpty()) {
1782     mRecordDB.Remove(*static_cast<nsHostKey*>(rec.get()));
1783     // If record is on a Queue, remove it
1784     mQueue.MaybeRemoveFromQ(rec, lock);
1785   }
1786 }
1787
1788 size_t nsHostResolver::SizeOfIncludingThis(MallocSizeOf mallocSizeOf) const {
1789   MutexAutoLock lock(mLock);
1790
1791   size_t n = mallocSizeOf(this);
1792
1793   n += mRecordDB.ShallowSizeOfExcludingThis(mallocSizeOf);
1794   for (const auto& entry : mRecordDB.Values()) {
1795     n += entry->SizeOfIncludingThis(mallocSizeOf);
1796   }
1797
1798   // The following fields aren't measured.
1799   // - mHighQ, mMediumQ, mLowQ, mEvictionQ, because they just point to
1800   //   nsHostRecords that also pointed to by entries |mRecordDB|, and
1801   //   measured when |mRecordDB| is measured.
1802
1803   return n;
1804 }
1805
1806 void nsHostResolver::ThreadFunc() {
1807   LOG(("DNS lookup thread - starting execution.\n"));
1808
1809 #if defined(RES_RETRY_ON_FAILURE)
1810   nsResState rs;
1811 #endif
1812   RefPtr<nsHostRecord> rec;
1813   RefPtr<AddrInfo> ai;
1814
1815   do {
1816     if (!rec) {
1817       RefPtr<nsHostRecord> tmpRec;
1818       if (!GetHostToLookup(getter_AddRefs(tmpRec))) {
1819         break;  // thread shutdown signal
1820       }
1821       // GetHostToLookup() returns an owning reference
1822       MOZ_ASSERT(tmpRec);
1823       rec.swap(tmpRec);
1824     }
1825
1826     LOG1(("DNS lookup thread - Calling getaddrinfo for host [%s].\n",
1827           rec->host.get()));
1828
1829     TimeStamp startTime = TimeStamp::Now();
1830     bool getTtl = rec->LoadGetTtl();
1831     TimeDuration inQueue = startTime - rec->mNativeStart;
1832     uint32_t ms = static_cast<uint32_t>(inQueue.ToMilliseconds());
1833     Telemetry::Accumulate(Telemetry::DNS_NATIVE_QUEUING, ms);
1834
1835     if (!rec->IsAddrRecord()) {
1836       LOG(("byType on DNS thread"));
1837       TypeRecordResultType result = AsVariant(mozilla::Nothing());
1838       uint32_t ttl = UINT32_MAX;
1839       nsresult status = ResolveHTTPSRecord(rec->host, rec->flags, result, ttl);
1840       mozilla::glean::networking::dns_native_count
1841           .EnumGet(rec->pb
1842                        ? glean::networking::DnsNativeCountLabel::eHttpsPrivate
1843                        : glean::networking::DnsNativeCountLabel::eHttpsRegular)
1844           .Add(1);
1845       CompleteLookupByType(rec, status, result, rec->mTRRSkippedReason, ttl,
1846                            rec->pb);
1847       rec = nullptr;
1848       continue;
1849     }
1850
1851     nsresult status =
1852         GetAddrInfo(rec->host, rec->af, rec->flags, getter_AddRefs(ai), getTtl);
1853 #if defined(RES_RETRY_ON_FAILURE)
1854     if (NS_FAILED(status) && rs.Reset()) {
1855       status = GetAddrInfo(rec->host, rec->af, rec->flags, getter_AddRefs(ai),
1856                            getTtl);
1857     }
1858 #endif
1859
1860     mozilla::glean::networking::dns_native_count
1861         .EnumGet(rec->pb ? glean::networking::DnsNativeCountLabel::ePrivate
1862                          : glean::networking::DnsNativeCountLabel::eRegular)
1863         .Add(1);
1864
1865     if (RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec)) {
1866       // obtain lock to check shutdown and manage inter-module telemetry
1867       MutexAutoLock lock(mLock);
1868
1869       if (!mShutdown) {
1870         TimeDuration elapsed = TimeStamp::Now() - startTime;
1871         if (NS_SUCCEEDED(status)) {
1872           if (!addrRec->addr_info_gencnt) {
1873             // Time for initial lookup.
1874             glean::networking::dns_lookup_time.AccumulateRawDuration(elapsed);
1875           } else if (!getTtl) {
1876             // Time for renewal; categorized by expiration strategy.
1877             glean::networking::dns_renewal_time.AccumulateRawDuration(elapsed);
1878           } else {
1879             // Time to get TTL; categorized by expiration strategy.
1880             glean::networking::dns_renewal_time_for_ttl.AccumulateRawDuration(
1881                 elapsed);
1882           }
1883         } else {
1884           glean::networking::dns_failed_lookup_time.AccumulateRawDuration(
1885               elapsed);
1886         }
1887       }
1888     }
1889
1890     LOG1(("DNS lookup thread - lookup completed for host [%s]: %s.\n",
1891           rec->host.get(), ai ? "success" : "failure: unknown host"));
1892
1893     if (LOOKUP_RESOLVEAGAIN ==
1894         CompleteLookup(rec, status, ai, rec->pb, rec->originSuffix,
1895                        rec->mTRRSkippedReason, nullptr)) {
1896       // leave 'rec' assigned and loop to make a renewed host resolve
1897       LOG(("DNS lookup thread - Re-resolving host [%s].\n", rec->host.get()));
1898     } else {
1899       rec = nullptr;
1900     }
1901   } while (true);
1902
1903   MutexAutoLock lock(mLock);
1904   mActiveTaskCount--;
1905   LOG(("DNS lookup thread - queue empty, task finished.\n"));
1906 }
1907
1908 void nsHostResolver::SetCacheLimits(uint32_t aMaxCacheEntries,
1909                                     uint32_t aDefaultCacheEntryLifetime,
1910                                     uint32_t aDefaultGracePeriod) {
1911   MutexAutoLock lock(mLock);
1912   mMaxCacheEntries = aMaxCacheEntries;
1913   mDefaultCacheLifetime = aDefaultCacheEntryLifetime;
1914   mDefaultGracePeriod = aDefaultGracePeriod;
1915 }
1916
1917 nsresult nsHostResolver::Create(uint32_t maxCacheEntries,
1918                                 uint32_t defaultCacheEntryLifetime,
1919                                 uint32_t defaultGracePeriod,
1920                                 nsHostResolver** result) {
1921   RefPtr<nsHostResolver> res = new nsHostResolver(
1922       maxCacheEntries, defaultCacheEntryLifetime, defaultGracePeriod);
1923
1924   nsresult rv = res->Init();
1925   if (NS_FAILED(rv)) {
1926     return rv;
1927   }
1928
1929   res.forget(result);
1930   return NS_OK;
1931 }
1932
1933 void nsHostResolver::GetDNSCacheEntries(nsTArray<DNSCacheEntries>* args) {
1934   MutexAutoLock lock(mLock);
1935   for (const auto& recordEntry : mRecordDB) {
1936     // We don't pay attention to address literals, only resolved domains.
1937     // Also require a host.
1938     nsHostRecord* rec = recordEntry.GetWeak();
1939     MOZ_ASSERT(rec, "rec should never be null here!");
1940
1941     if (!rec) {
1942       continue;
1943     }
1944
1945     // For now we only show A/AAAA records.
1946     if (!rec->IsAddrRecord()) {
1947       continue;
1948     }
1949
1950     RefPtr<AddrHostRecord> addrRec = do_QueryObject(rec);
1951     MOZ_ASSERT(addrRec);
1952     if (!addrRec || !addrRec->addr_info) {
1953       continue;
1954     }
1955
1956     DNSCacheEntries info;
1957     info.hostname = rec->host;
1958     info.family = rec->af;
1959     info.expiration =
1960         (int64_t)(rec->mValidEnd - TimeStamp::NowLoRes()).ToSeconds();
1961     if (info.expiration <= 0) {
1962       // We only need valid DNS cache entries
1963       continue;
1964     }
1965
1966     {
1967       MutexAutoLock lock(addrRec->addr_info_lock);
1968       for (const auto& addr : addrRec->addr_info->Addresses()) {
1969         char buf[kIPv6CStrBufSize];
1970         if (addr.ToStringBuffer(buf, sizeof(buf))) {
1971           info.hostaddr.AppendElement(buf);
1972         }
1973       }
1974       info.TRR = addrRec->addr_info->IsTRR();
1975     }
1976
1977     info.originAttributesSuffix = recordEntry.GetKey().originSuffix;
1978     info.flags = nsPrintfCString("%u|0x%x|%u|%d|%s", rec->type, rec->flags,
1979                                  rec->af, rec->pb, rec->mTrrServer.get());
1980
1981     args->AppendElement(std::move(info));
1982   }
1983 }
1984
1985 #undef LOG
1986 #undef LOG_ENABLED