Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1453 insertions, 0 deletions

diff --git a/netwerk/dns/nsDNSService2.cpp b/netwerk/dns/nsDNSService2.cpp
new file mode 100644
index 0000000000..443c226116
--- /dev/null
+++ b/netwerk/dns/nsDNSService2.cpp
@@ -0,0 +1,1453 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et tw=80 : */
+/* 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 "nsDNSService2.h"
+#include "nsIDNSRecord.h"
+#include "nsIDNSListener.h"
+#include "nsIDNSByTypeRecord.h"
+#include "nsICancelable.h"
+#include "nsIPrefBranch.h"
+#include "nsIOService.h"
+#include "nsIXPConnect.h"
+#include "nsProxyRelease.h"
+#include "nsReadableUtils.h"
+#include "nsString.h"
+#include "nsNetCID.h"
+#include "nsError.h"
+#include "nsDNSPrefetch.h"
+#include "nsThreadUtils.h"
+#include "nsIProtocolProxyService.h"
+#include "prsystem.h"
+#include "prnetdb.h"
+#include "prmon.h"
+#include "prio.h"
+#include "plstr.h"
+#include "nsCharSeparatedTokenizer.h"
+#include "nsNetAddr.h"
+#include "nsProxyRelease.h"
+#include "nsQueryObject.h"
+#include "nsIObserverService.h"
+#include "nsINetworkLinkService.h"
+#include "DNSResolverInfo.h"
+#include "TRRService.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/net/NeckoCommon.h"
+#include "mozilla/net/ChildDNSService.h"
+#include "mozilla/net/DNSListenerProxy.h"
+#include "mozilla/Services.h"
+#include "mozilla/StaticPrefs_network.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/SyncRunnable.h"
+#include "mozilla/TextUtils.h"
+#include "mozilla/Utf8.h"
+
+using namespace mozilla;
+using namespace mozilla::net;
+
+static const char kPrefDnsCacheEntries[] = "network.dnsCacheEntries";
+static const char kPrefDnsCacheExpiration[] = "network.dnsCacheExpiration";
+static const char kPrefDnsCacheGrace[] =
+    "network.dnsCacheExpirationGracePeriod";
+static const char kPrefIPv4OnlyDomains[] = "network.dns.ipv4OnlyDomains";
+static const char kPrefDisableIPv6[] = "network.dns.disableIPv6";
+static const char kPrefDisablePrefetch[] = "network.dns.disablePrefetch";
+static const char kPrefBlockDotOnion[] = "network.dns.blockDotOnion";
+static const char kPrefDnsLocalDomains[] = "network.dns.localDomains";
+static const char kPrefDnsForceResolve[] = "network.dns.forceResolve";
+static const char kPrefDnsOfflineLocalhost[] = "network.dns.offline-localhost";
+static const char kPrefDnsNotifyResolution[] = "network.dns.notifyResolution";
+static const char kPrefNetworkProxySOCKS[] = "network.proxy.socks";
+
+//-----------------------------------------------------------------------------
+
+class nsDNSRecord : public nsIDNSAddrRecord {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIDNSRECORD
+  NS_DECL_NSIDNSADDRRECORD
+
+  explicit nsDNSRecord(nsHostRecord* hostRecord)
+      : mIterGenCnt(-1), mDone(false) {
+    mHostRecord = do_QueryObject(hostRecord);
+  }
+
+ private:
+  virtual ~nsDNSRecord() = default;
+
+  RefPtr<AddrHostRecord> mHostRecord;
+  // Since mIter is holding a weak reference to the NetAddr array we must
+  // make sure it is not released. So we also keep a RefPtr to the AddrInfo
+  // which is immutable.
+  RefPtr<AddrInfo> mAddrInfo;
+  nsTArray<NetAddr>::const_iterator mIter;
+  const NetAddr* iter() {
+    if (!mIter.GetArray()) {
+      return nullptr;
+    }
+    if (mIter.GetArray()->end() == mIter) {
+      return nullptr;
+    }
+    return &*mIter;
+  }
+
+  int mIterGenCnt;  // the generation count of
+                    // mHostRecord->addr_info when we
+                    // start iterating
+  bool mDone;
+};
+
+NS_IMPL_ISUPPORTS(nsDNSRecord, nsIDNSRecord, nsIDNSAddrRecord)
+
+NS_IMETHODIMP
+nsDNSRecord::GetCanonicalName(nsACString& result) {
+  // this method should only be called if we have a CNAME
+  NS_ENSURE_TRUE(mHostRecord->flags & nsHostResolver::RES_CANON_NAME,
+                 NS_ERROR_NOT_AVAILABLE);
+
+  MutexAutoLock lock(mHostRecord->addr_info_lock);
+
+  // if the record is for an IP address literal, then the canonical
+  // host name is the IP address literal.
+  if (!mHostRecord->addr_info) {
+    result = mHostRecord->host;
+    return NS_OK;
+  }
+
+  if (mHostRecord->addr_info->CanonicalHostname().IsEmpty()) {
+    result = mHostRecord->addr_info->Hostname();
+  } else {
+    result = mHostRecord->addr_info->CanonicalHostname();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::IsTRR(bool* retval) {
+  MutexAutoLock lock(mHostRecord->addr_info_lock);
+  if (mHostRecord->addr_info) {
+    *retval = mHostRecord->addr_info->IsTRR();
+  } else {
+    *retval = false;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetTrrFetchDuration(double* aTime) {
+  MutexAutoLock lock(mHostRecord->addr_info_lock);
+  if (mHostRecord->addr_info && mHostRecord->addr_info->IsTRR()) {
+    *aTime = mHostRecord->addr_info->GetTrrFetchDuration();
+  } else {
+    *aTime = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetTrrFetchDurationNetworkOnly(double* aTime) {
+  MutexAutoLock lock(mHostRecord->addr_info_lock);
+  if (mHostRecord->addr_info && mHostRecord->addr_info->IsTRR()) {
+    *aTime = mHostRecord->addr_info->GetTrrFetchDurationNetworkOnly();
+  } else {
+    *aTime = 0;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetNextAddr(uint16_t port, NetAddr* addr) {
+  if (mDone) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  mHostRecord->addr_info_lock.Lock();
+  if (mHostRecord->addr_info) {
+    if (mIterGenCnt != mHostRecord->addr_info_gencnt) {
+      // mHostRecord->addr_info has changed, restart the iteration.
+      mIter = nsTArray<NetAddr>::const_iterator();
+      mIterGenCnt = mHostRecord->addr_info_gencnt;
+      // Make sure to hold a RefPtr to the AddrInfo so we can iterate through
+      // the NetAddr array.
+      mAddrInfo = mHostRecord->addr_info;
+    }
+
+    bool startedFresh = !iter();
+
+    do {
+      if (!iter()) {
+        mIter = mAddrInfo->Addresses().begin();
+      } else {
+        mIter++;
+      }
+    } while (iter() && mHostRecord->Blocklisted(iter()));
+
+    if (!iter() && startedFresh) {
+      // If everything was blocklisted we want to reset the blocklist (and
+      // likely relearn it) and return the first address. That is better
+      // than nothing.
+      mHostRecord->ResetBlocklist();
+      mIter = mAddrInfo->Addresses().begin();
+    }
+
+    if (iter()) {
+      *addr = *mIter;
+    }
+
+    mHostRecord->addr_info_lock.Unlock();
+
+    if (!iter()) {
+      mDone = true;
+      mIter = nsTArray<NetAddr>::const_iterator();
+      mAddrInfo = nullptr;
+      mIterGenCnt = -1;
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+  } else {
+    mHostRecord->addr_info_lock.Unlock();
+
+    if (!mHostRecord->addr) {
+      // Both mHostRecord->addr_info and mHostRecord->addr are null.
+      // This can happen if mHostRecord->addr_info expired and the
+      // attempt to reresolve it failed.
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    memcpy(addr, mHostRecord->addr.get(), sizeof(NetAddr));
+    mDone = true;
+  }
+
+  // set given port
+  port = htons(port);
+  if (addr->raw.family == AF_INET) {
+    addr->inet.port = port;
+  } else if (addr->raw.family == AF_INET6) {
+    addr->inet6.port = port;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetAddresses(nsTArray<NetAddr>& aAddressArray) {
+  if (mDone) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  mHostRecord->addr_info_lock.Lock();
+  if (mHostRecord->addr_info) {
+    for (const auto& address : mHostRecord->addr_info->Addresses()) {
+      if (mHostRecord->Blocklisted(&address)) {
+        continue;
+      }
+      NetAddr* addr = aAddressArray.AppendElement(address);
+      if (addr->raw.family == AF_INET) {
+        addr->inet.port = 0;
+      } else if (addr->raw.family == AF_INET6) {
+        addr->inet6.port = 0;
+      }
+    }
+    mHostRecord->addr_info_lock.Unlock();
+  } else {
+    mHostRecord->addr_info_lock.Unlock();
+
+    if (!mHostRecord->addr) {
+      return NS_ERROR_NOT_AVAILABLE;
+    }
+    NetAddr* addr = aAddressArray.AppendElement(NetAddr());
+    memcpy(addr, mHostRecord->addr.get(), sizeof(NetAddr));
+    if (addr->raw.family == AF_INET) {
+      addr->inet.port = 0;
+    } else if (addr->raw.family == AF_INET6) {
+      addr->inet6.port = 0;
+    }
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetScriptableNextAddr(uint16_t port, nsINetAddr** result) {
+  NetAddr addr;
+  nsresult rv = GetNextAddr(port, &addr);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  RefPtr<nsNetAddr> netaddr = new nsNetAddr(&addr);
+  netaddr.forget(result);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetNextAddrAsString(nsACString& result) {
+  NetAddr addr;
+  nsresult rv = GetNextAddr(0, &addr);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  char buf[kIPv6CStrBufSize];
+  if (addr.ToStringBuffer(buf, sizeof(buf))) {
+    result.Assign(buf);
+    return NS_OK;
+  }
+  NS_ERROR("NetAddrToString failed unexpectedly");
+  return NS_ERROR_FAILURE;  // conversion failed for some reason
+}
+
+NS_IMETHODIMP
+nsDNSRecord::HasMore(bool* result) {
+  if (mDone) {
+    *result = false;
+    return NS_OK;
+  }
+
+  nsTArray<NetAddr>::const_iterator iterCopy = mIter;
+  int iterGenCntCopy = mIterGenCnt;
+
+  NetAddr addr;
+  *result = NS_SUCCEEDED(GetNextAddr(0, &addr));
+
+  mIter = iterCopy;
+  mIterGenCnt = iterGenCntCopy;
+  mDone = false;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::Rewind() {
+  mIter = nsTArray<NetAddr>::const_iterator();
+  mIterGenCnt = -1;
+  mDone = false;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::ReportUnusable(uint16_t aPort) {
+  // right now we don't use the port in the blocklist
+
+  MutexAutoLock lock(mHostRecord->addr_info_lock);
+
+  // Check that we are using a real addr_info (as opposed to a single
+  // constant address), and that the generation count is valid. Otherwise,
+  // ignore the report.
+
+  if (mHostRecord->addr_info && mIterGenCnt == mHostRecord->addr_info_gencnt &&
+      iter()) {
+    mHostRecord->ReportUnusable(iter());
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSRecord::GetEffectiveTRRMode(uint32_t* aMode) {
+  *aMode = mHostRecord->EffectiveTRRMode();
+  return NS_OK;
+}
+
+class nsDNSByTypeRecord : public nsIDNSByTypeRecord,
+                          public nsIDNSTXTRecord,
+                          public nsIDNSHTTPSSVCRecord {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSIDNSRECORD
+  NS_DECL_NSIDNSBYTYPERECORD
+  NS_DECL_NSIDNSTXTRECORD
+  NS_DECL_NSIDNSHTTPSSVCRECORD
+
+  explicit nsDNSByTypeRecord(nsHostRecord* hostRecord) {
+    mHostRecord = do_QueryObject(hostRecord);
+  }
+
+ private:
+  virtual ~nsDNSByTypeRecord() = default;
+  RefPtr<TypeHostRecord> mHostRecord;
+};
+
+NS_IMPL_ISUPPORTS(nsDNSByTypeRecord, nsIDNSRecord, nsIDNSByTypeRecord,
+                  nsIDNSTXTRecord, nsIDNSHTTPSSVCRecord)
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetType(uint32_t* aType) {
+  *aType = mHostRecord->GetType();
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetRecords(CopyableTArray<nsCString>& aRecords) {
+  // deep copy
+  return mHostRecord->GetRecords(aRecords);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetRecordsAsOneString(nsACString& aRecords) {
+  // deep copy
+  return mHostRecord->GetRecordsAsOneString(aRecords);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetRecords(nsTArray<RefPtr<nsISVCBRecord>>& aRecords) {
+  return mHostRecord->GetRecords(aRecords);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetServiceModeRecord(bool aNoHttp2, bool aNoHttp3,
+                                        nsISVCBRecord** aRecord) {
+  return mHostRecord->GetServiceModeRecord(aNoHttp2, aNoHttp3, aRecord);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetAllRecordsWithEchConfig(
+    bool aNoHttp2, bool aNoHttp3, bool* aAllRecordsHaveEchConfig,
+    bool* aAllRecordsInH3ExcludedList,
+    nsTArray<RefPtr<nsISVCBRecord>>& aResult) {
+  return mHostRecord->GetAllRecordsWithEchConfig(
+      aNoHttp2, aNoHttp3, aAllRecordsHaveEchConfig, aAllRecordsInH3ExcludedList,
+      aResult);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetHasIPAddresses(bool* aResult) {
+  return mHostRecord->GetHasIPAddresses(aResult);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetAllRecordsExcluded(bool* aResult) {
+  return mHostRecord->GetAllRecordsExcluded(aResult);
+}
+
+NS_IMETHODIMP
+nsDNSByTypeRecord::GetResults(mozilla::net::TypeRecordResultType* aResults) {
+  *aResults = mHostRecord->GetResults();
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+
+class nsDNSAsyncRequest final : public nsResolveHostCallback,
+                                public nsICancelable {
+ public:
+  NS_DECL_THREADSAFE_ISUPPORTS
+  NS_DECL_NSICANCELABLE
+
+  nsDNSAsyncRequest(nsHostResolver* res, const nsACString& host,
+                    const nsACString& trrServer, uint16_t type,
+                    const OriginAttributes& attrs, nsIDNSListener* listener,
+                    uint16_t flags, uint16_t af)
+      : mResolver(res),
+        mHost(host),
+        mTrrServer(trrServer),
+        mType(type),
+        mOriginAttributes(attrs),
+        mListener(listener),
+        mFlags(flags),
+        mAF(af) {}
+
+  void OnResolveHostComplete(nsHostResolver*, nsHostRecord*, nsresult) override;
+  // Returns TRUE if the DNS listener arg is the same as the member listener
+  // Used in Cancellations to remove DNS requests associated with a
+  // particular hostname and nsIDNSListener
+  bool EqualsAsyncListener(nsIDNSListener* aListener) override;
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf) const override;
+
+  RefPtr<nsHostResolver> mResolver;
+  nsCString mHost;       // hostname we're resolving
+  nsCString mTrrServer;  // A trr server to be used.
+  uint16_t mType;
+  const OriginAttributes
+      mOriginAttributes;  // The originAttributes for this resolving
+  nsCOMPtr<nsIDNSListener> mListener;
+  uint16_t mFlags;
+  uint16_t mAF;
+
+ private:
+  virtual ~nsDNSAsyncRequest() = default;
+};
+
+NS_IMPL_ISUPPORTS(nsDNSAsyncRequest, nsICancelable)
+
+void nsDNSAsyncRequest::OnResolveHostComplete(nsHostResolver* resolver,
+                                              nsHostRecord* hostRecord,
+                                              nsresult status) {
+  // need to have an owning ref when we issue the callback to enable
+  // the caller to be able to addref/release multiple times without
+  // destroying the record prematurely.
+  nsCOMPtr<nsIDNSRecord> rec;
+  if (NS_SUCCEEDED(status)) {
+    MOZ_ASSERT(hostRecord, "no host record");
+    if (hostRecord->type != nsDNSService::RESOLVE_TYPE_DEFAULT) {
+      rec = new nsDNSByTypeRecord(hostRecord);
+    } else {
+      rec = new nsDNSRecord(hostRecord);
+    }
+  }
+
+  mListener->OnLookupComplete(this, rec, status);
+  mListener = nullptr;
+}
+
+bool nsDNSAsyncRequest::EqualsAsyncListener(nsIDNSListener* aListener) {
+  uintptr_t originalListenerAddr = reinterpret_cast<uintptr_t>(mListener.get());
+  RefPtr<DNSListenerProxy> wrapper = do_QueryObject(mListener);
+  if (wrapper) {
+    originalListenerAddr = wrapper->GetOriginalListenerAddress();
+  }
+
+  uintptr_t listenerAddr = reinterpret_cast<uintptr_t>(aListener);
+  return (listenerAddr == originalListenerAddr);
+}
+
+size_t nsDNSAsyncRequest::SizeOfIncludingThis(MallocSizeOf mallocSizeOf) const {
+  size_t n = mallocSizeOf(this);
+
+  // The following fields aren't measured.
+  // - mHost, because it's a non-owning pointer
+  // - mResolver, because it's a non-owning pointer
+  // - mListener, because it's a non-owning pointer
+
+  return n;
+}
+
+NS_IMETHODIMP
+nsDNSAsyncRequest::Cancel(nsresult reason) {
+  NS_ENSURE_ARG(NS_FAILED(reason));
+  mResolver->DetachCallback(mHost, mTrrServer, mType, mOriginAttributes, mFlags,
+                            mAF, this, reason);
+  return NS_OK;
+}
+
+//-----------------------------------------------------------------------------
+
+class nsDNSSyncRequest : public nsResolveHostCallback {
+  NS_DECL_THREADSAFE_ISUPPORTS
+ public:
+  explicit nsDNSSyncRequest(PRMonitor* mon)
+      : mDone(false), mStatus(NS_OK), mMonitor(mon) {}
+
+  void OnResolveHostComplete(nsHostResolver*, nsHostRecord*, nsresult) override;
+  bool EqualsAsyncListener(nsIDNSListener* aListener) override;
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf) const override;
+
+  bool mDone;
+  nsresult mStatus;
+  RefPtr<nsHostRecord> mHostRecord;
+
+ private:
+  virtual ~nsDNSSyncRequest() = default;
+
+  PRMonitor* mMonitor;
+};
+
+NS_IMPL_ISUPPORTS0(nsDNSSyncRequest)
+
+void nsDNSSyncRequest::OnResolveHostComplete(nsHostResolver* resolver,
+                                             nsHostRecord* hostRecord,
+                                             nsresult status) {
+  // store results, and wake up nsDNSService::Resolve to process results.
+  PR_EnterMonitor(mMonitor);
+  mDone = true;
+  mStatus = status;
+  mHostRecord = hostRecord;
+  PR_Notify(mMonitor);
+  PR_ExitMonitor(mMonitor);
+}
+
+bool nsDNSSyncRequest::EqualsAsyncListener(nsIDNSListener* aListener) {
+  // Sync request: no listener to compare
+  return false;
+}
+
+size_t nsDNSSyncRequest::SizeOfIncludingThis(MallocSizeOf mallocSizeOf) const {
+  size_t n = mallocSizeOf(this);
+
+  // The following fields aren't measured.
+  // - mHostRecord, because it's a non-owning pointer
+
+  // Measurement of the following members may be added later if DMD finds it
+  // is worthwhile:
+  // - mMonitor
+
+  return n;
+}
+
+class NotifyDNSResolution : public Runnable {
+ public:
+  explicit NotifyDNSResolution(const nsACString& aHostname)
+      : mozilla::Runnable("NotifyDNSResolution"), mHostname(aHostname) {}
+
+  NS_IMETHOD Run() override {
+    MOZ_ASSERT(NS_IsMainThread());
+    nsCOMPtr<nsIObserverService> obs = services::GetObserverService();
+    if (obs) {
+      obs->NotifyObservers(nullptr, "dns-resolution-request",
+                           NS_ConvertUTF8toUTF16(mHostname).get());
+    }
+    return NS_OK;
+  }
+
+ private:
+  nsCString mHostname;
+};
+
+//-----------------------------------------------------------------------------
+
+nsDNSService::nsDNSService()
+    : mLock("nsDNSServer.mLock"),
+      mDisableIPv6(false),
+      mDisablePrefetch(false),
+      mBlockDotOnion(false),
+      mNotifyResolution(false),
+      mOfflineLocalhost(false),
+      mForceResolveOn(false),
+      mTrrService(nullptr),
+      mHasSocksProxy(false),
+      mResCacheEntries(0),
+      mResCacheExpiration(0),
+      mResCacheGrace(0),
+      mResolverPrefsUpdated(false) {}
+
+nsDNSService::~nsDNSService() = default;
+
+NS_IMPL_ISUPPORTS(nsDNSService, nsIDNSService, nsPIDNSService, nsIObserver,
+                  nsIMemoryReporter)
+
+/******************************************************************************
+ * nsDNSService impl:
+ * singleton instance ctor/dtor methods
+ ******************************************************************************/
+static StaticRefPtr<nsDNSService> gDNSService;
+
+already_AddRefed<nsIDNSService> nsDNSService::GetXPCOMSingleton() {
+  if (nsIOService::UseSocketProcess()) {
+    if (XRE_IsSocketProcess()) {
+      return GetSingleton();
+    }
+
+    if (XRE_IsContentProcess() || XRE_IsParentProcess()) {
+      return ChildDNSService::GetSingleton();
+    }
+
+    return nullptr;
+  }
+
+  if (XRE_IsParentProcess()) {
+    return GetSingleton();
+  }
+
+  if (XRE_IsContentProcess() || XRE_IsSocketProcess()) {
+    return ChildDNSService::GetSingleton();
+  }
+
+  return nullptr;
+}
+
+already_AddRefed<nsDNSService> nsDNSService::GetSingleton() {
+  MOZ_ASSERT_IF(nsIOService::UseSocketProcess(), XRE_IsSocketProcess());
+  MOZ_ASSERT_IF(!nsIOService::UseSocketProcess(), XRE_IsParentProcess());
+
+  if (!gDNSService) {
+    if (!NS_IsMainThread()) {
+      return nullptr;
+    }
+    gDNSService = new nsDNSService();
+    if (NS_SUCCEEDED(gDNSService->Init())) {
+      ClearOnShutdown(&gDNSService);
+    } else {
+      gDNSService = nullptr;
+    }
+  }
+
+  return do_AddRef(gDNSService);
+}
+
+nsresult nsDNSService::ReadPrefs(const char* name) {
+  bool tmpbool;
+  uint32_t tmpint;
+  mResolverPrefsUpdated = false;
+
+  // resolver-specific prefs first
+  if (!name || !strcmp(name, kPrefDnsCacheEntries)) {
+    if (NS_SUCCEEDED(Preferences::GetUint(kPrefDnsCacheEntries, &tmpint))) {
+      if (!name || (tmpint != mResCacheEntries)) {
+        mResCacheEntries = tmpint;
+        mResolverPrefsUpdated = true;
+      }
+    }
+  }
+  if (!name || !strcmp(name, kPrefDnsCacheExpiration)) {
+    if (NS_SUCCEEDED(Preferences::GetUint(kPrefDnsCacheExpiration, &tmpint))) {
+      if (!name || (tmpint != mResCacheExpiration)) {
+        mResCacheExpiration = tmpint;
+        mResolverPrefsUpdated = true;
+      }
+    }
+  }
+  if (!name || !strcmp(name, kPrefDnsCacheGrace)) {
+    if (NS_SUCCEEDED(Preferences::GetUint(kPrefDnsCacheGrace, &tmpint))) {
+      if (!name || (tmpint != mResCacheGrace)) {
+        mResCacheGrace = tmpint;
+        mResolverPrefsUpdated = true;
+      }
+    }
+  }
+
+  // DNSservice prefs
+  if (!name || !strcmp(name, kPrefDisableIPv6)) {
+    if (NS_SUCCEEDED(Preferences::GetBool(kPrefDisableIPv6, &tmpbool))) {
+      mDisableIPv6 = tmpbool;
+    }
+  }
+  if (!name || !strcmp(name, kPrefDnsOfflineLocalhost)) {
+    if (NS_SUCCEEDED(
+            Preferences::GetBool(kPrefDnsOfflineLocalhost, &tmpbool))) {
+      mOfflineLocalhost = tmpbool;
+    }
+  }
+  if (!name || !strcmp(name, kPrefDisablePrefetch)) {
+    if (NS_SUCCEEDED(Preferences::GetBool(kPrefDisablePrefetch, &tmpbool))) {
+      mDisablePrefetch = tmpbool;
+    }
+  }
+  if (!name || !strcmp(name, kPrefBlockDotOnion)) {
+    if (NS_SUCCEEDED(Preferences::GetBool(kPrefBlockDotOnion, &tmpbool))) {
+      mBlockDotOnion = tmpbool;
+    }
+  }
+  if (!name || !strcmp(name, kPrefDnsNotifyResolution)) {
+    if (NS_SUCCEEDED(
+            Preferences::GetBool(kPrefDnsNotifyResolution, &tmpbool))) {
+      mNotifyResolution = tmpbool;
+    }
+  }
+  if (!name || !strcmp(name, kPrefNetworkProxySOCKS)) {
+    nsAutoCString socks;
+    if (NS_SUCCEEDED(Preferences::GetCString(kPrefNetworkProxySOCKS, socks))) {
+      mHasSocksProxy = !socks.IsEmpty();
+    }
+  }
+  if (!name || !strcmp(name, kPrefIPv4OnlyDomains)) {
+    Preferences::GetCString(kPrefIPv4OnlyDomains, mIPv4OnlyDomains);
+  }
+  if (!name || !strcmp(name, kPrefDnsLocalDomains)) {
+    nsCString localDomains;
+    Preferences::GetCString(kPrefDnsLocalDomains, localDomains);
+    MutexAutoLock lock(mLock);
+    mLocalDomains.Clear();
+    for (const auto& token :
+         nsCCharSeparatedTokenizerTemplate<NS_IsAsciiWhitespace,
+                                           nsTokenizerFlags::SeparatorOptional>(
+             localDomains, ',')
+             .ToRange()) {
+      mLocalDomains.PutEntry(token);
+    }
+  }
+  if (!name || !strcmp(name, kPrefDnsForceResolve)) {
+    Preferences::GetCString(kPrefDnsForceResolve, mForceResolve);
+    mForceResolveOn = !mForceResolve.IsEmpty();
+  }
+
+  if (StaticPrefs::network_proxy_type() ==
+      nsIProtocolProxyService::PROXYCONFIG_MANUAL) {
+    // Disable prefetching either by explicit preference or if a
+    // manual proxy is configured
+    mDisablePrefetch = true;
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::Init() {
+  MOZ_ASSERT(!mResolver);
+  MOZ_ASSERT(NS_IsMainThread());
+
+  ReadPrefs(nullptr);
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->AddObserver(this, "last-pb-context-exited", false);
+    observerService->AddObserver(this, NS_NETWORK_LINK_TOPIC, false);
+    observerService->AddObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID, false);
+  }
+
+  RefPtr<nsHostResolver> res;
+  nsresult rv = nsHostResolver::Create(mResCacheEntries, mResCacheExpiration,
+                                       mResCacheGrace, getter_AddRefs(res));
+  if (NS_SUCCEEDED(rv)) {
+    // now, set all of our member variables while holding the lock
+    MutexAutoLock lock(mLock);
+    mResolver = res;
+  }
+
+  nsCOMPtr<nsIPrefBranch> prefs = do_GetService(NS_PREFSERVICE_CONTRACTID);
+  if (prefs) {
+    // register as prefs observer
+    prefs->AddObserver(kPrefDnsCacheEntries, this, false);
+    prefs->AddObserver(kPrefDnsCacheExpiration, this, false);
+    prefs->AddObserver(kPrefDnsCacheGrace, this, false);
+    prefs->AddObserver(kPrefIPv4OnlyDomains, this, false);
+    prefs->AddObserver(kPrefDnsLocalDomains, this, false);
+    prefs->AddObserver(kPrefDnsForceResolve, this, false);
+    prefs->AddObserver(kPrefDisableIPv6, this, false);
+    prefs->AddObserver(kPrefDnsOfflineLocalhost, this, false);
+    prefs->AddObserver(kPrefDisablePrefetch, this, false);
+    prefs->AddObserver(kPrefBlockDotOnion, this, false);
+    prefs->AddObserver(kPrefDnsNotifyResolution, this, false);
+
+    // Monitor these to see if there is a change in proxy configuration
+    prefs->AddObserver(kPrefNetworkProxySOCKS, this, false);
+  }
+
+  nsDNSPrefetch::Initialize(this);
+
+  RegisterWeakMemoryReporter(this);
+
+  mTrrService = new TRRService();
+  if (NS_FAILED(mTrrService->Init())) {
+    mTrrService = nullptr;
+  }
+
+  nsCOMPtr<nsIIDNService> idn = do_GetService(NS_IDNSERVICE_CONTRACTID);
+  mIDN = idn;
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::Shutdown() {
+  UnregisterWeakMemoryReporter(this);
+
+  RefPtr<nsHostResolver> res;
+  {
+    MutexAutoLock lock(mLock);
+    res = mResolver;
+    mResolver = nullptr;
+  }
+  if (res) {
+    res->Shutdown();
+  }
+
+  nsCOMPtr<nsIObserverService> observerService =
+      mozilla::services::GetObserverService();
+  if (observerService) {
+    observerService->RemoveObserver(this, NS_NETWORK_LINK_TOPIC);
+    observerService->RemoveObserver(this, "last-pb-context-exited");
+    observerService->RemoveObserver(this, NS_XPCOM_SHUTDOWN_OBSERVER_ID);
+  }
+
+  return NS_OK;
+}
+
+bool nsDNSService::GetOffline() const {
+  bool offline = false;
+  nsCOMPtr<nsIIOService> io = do_GetService(NS_IOSERVICE_CONTRACTID);
+  if (io) {
+    io->GetOffline(&offline);
+  }
+  return offline;
+}
+
+NS_IMETHODIMP
+nsDNSService::GetPrefetchEnabled(bool* outVal) {
+  MutexAutoLock lock(mLock);
+  *outVal = !mDisablePrefetch;
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::SetPrefetchEnabled(bool inVal) {
+  MutexAutoLock lock(mLock);
+  mDisablePrefetch = !inVal;
+  return NS_OK;
+}
+
+bool nsDNSService::DNSForbiddenByActiveProxy(const nsACString& aHostname,
+                                             uint32_t flags) {
+  if (flags & nsIDNSService::RESOLVE_IGNORE_SOCKS_DNS) {
+    return false;
+  }
+
+  // We should avoid doing DNS when a proxy is in use.
+  PRNetAddr tempAddr;
+  if (StaticPrefs::network_proxy_type() ==
+          nsIProtocolProxyService::PROXYCONFIG_MANUAL &&
+      mHasSocksProxy && StaticPrefs::network_proxy_socks_remote_dns()) {
+    // Allow IP lookups through, but nothing else.
+    if (PR_StringToNetAddr(nsCString(aHostname).get(), &tempAddr) !=
+        PR_SUCCESS) {
+      return true;
+    }
+  }
+  return false;
+}
+
+nsresult nsDNSService::PreprocessHostname(bool aLocalDomain,
+                                          const nsACString& aInput,
+                                          nsIIDNService* aIDN,
+                                          nsACString& aACE) {
+  // Enforce RFC 7686
+  if (mBlockDotOnion && StringEndsWith(aInput, ".onion"_ns)) {
+    return NS_ERROR_UNKNOWN_HOST;
+  }
+
+  if (aLocalDomain) {
+    aACE.AssignLiteral("localhost");
+    return NS_OK;
+  }
+
+  if (mTrrService && mTrrService->MaybeBootstrap(aInput, aACE)) {
+    return NS_OK;
+  }
+
+  if (mForceResolveOn) {
+    MutexAutoLock lock(mLock);
+    if (!aInput.LowerCaseEqualsASCII("localhost") &&
+        !aInput.LowerCaseEqualsASCII("127.0.0.1")) {
+      aACE.Assign(mForceResolve);
+      return NS_OK;
+    }
+  }
+
+  if (!aIDN || IsAscii(aInput)) {
+    aACE = aInput;
+    return NS_OK;
+  }
+
+  if (!(IsUtf8(aInput) && NS_SUCCEEDED(aIDN->ConvertUTF8toACE(aInput, aACE)))) {
+    return NS_ERROR_FAILURE;
+  }
+  return NS_OK;
+}
+
+nsresult nsDNSService::AsyncResolveInternal(
+    const nsACString& aHostname, uint16_t type, uint32_t flags,
+    nsIDNSResolverInfo* aResolver, nsIDNSListener* aListener,
+    nsIEventTarget* target_, const OriginAttributes& aOriginAttributes,
+    nsICancelable** result) {
+  // grab reference to global host resolver and IDN service.  beware
+  // simultaneous shutdown!!
+  RefPtr<nsHostResolver> res;
+  nsCOMPtr<nsIIDNService> idn;
+  nsCOMPtr<nsIEventTarget> target = target_;
+  nsCOMPtr<nsIDNSListener> listener = aListener;
+  bool localDomain = false;
+  {
+    MutexAutoLock lock(mLock);
+
+    if (mDisablePrefetch && (flags & RESOLVE_SPECULATE)) {
+      return NS_ERROR_DNS_LOOKUP_QUEUE_FULL;
+    }
+
+    res = mResolver;
+    idn = mIDN;
+    localDomain = mLocalDomains.GetEntry(aHostname);
+  }
+
+  if (mNotifyResolution) {
+    NS_DispatchToMainThread(new NotifyDNSResolution(aHostname));
+  }
+
+  if (!res) {
+    return NS_ERROR_OFFLINE;
+  }
+
+  if ((type != RESOLVE_TYPE_DEFAULT) && (type != RESOLVE_TYPE_TXT) &&
+      (type != RESOLVE_TYPE_HTTPSSVC)) {
+    return NS_ERROR_INVALID_ARG;
+  }
+
+  if (DNSForbiddenByActiveProxy(aHostname, flags)) {
+    // nsHostResolver returns NS_ERROR_UNKNOWN_HOST for lots of reasons.
+    // We use a different error code to differentiate this failure and to make
+    // it clear(er) where this error comes from.
+    return NS_ERROR_UNKNOWN_PROXY_HOST;
+  }
+
+  nsCString hostname;
+  nsresult rv = PreprocessHostname(localDomain, aHostname, idn, hostname);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (GetOffline() &&
+      (!mOfflineLocalhost || !hostname.LowerCaseEqualsASCII("localhost"))) {
+    flags |= RESOLVE_OFFLINE;
+  }
+
+  // make sure JS callers get notification on the main thread
+  nsCOMPtr<nsIXPConnectWrappedJS> wrappedListener = do_QueryInterface(listener);
+  if (wrappedListener && !target) {
+    target = GetMainThreadEventTarget();
+  }
+
+  if (target) {
+    listener = new DNSListenerProxy(listener, target);
+  }
+
+  uint16_t af =
+      (type != RESOLVE_TYPE_DEFAULT) ? 0 : GetAFForLookup(hostname, flags);
+
+  MOZ_ASSERT(listener);
+  RefPtr<nsDNSAsyncRequest> req =
+      new nsDNSAsyncRequest(res, hostname, DNSResolverInfo::URL(aResolver),
+                            type, aOriginAttributes, listener, flags, af);
+  if (!req) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  rv = res->ResolveHost(req->mHost, DNSResolverInfo::URL(aResolver), type,
+                        req->mOriginAttributes, flags, af, req);
+  req.forget(result);
+  return rv;
+}
+
+nsresult nsDNSService::CancelAsyncResolveInternal(
+    const nsACString& aHostname, uint16_t aType, uint32_t aFlags,
+    nsIDNSResolverInfo* aResolver, nsIDNSListener* aListener, nsresult aReason,
+    const OriginAttributes& aOriginAttributes) {
+  // grab reference to global host resolver and IDN service.  beware
+  // simultaneous shutdown!!
+  RefPtr<nsHostResolver> res;
+  nsCOMPtr<nsIIDNService> idn;
+  bool localDomain = false;
+  {
+    MutexAutoLock lock(mLock);
+
+    if (mDisablePrefetch && (aFlags & RESOLVE_SPECULATE)) {
+      return NS_ERROR_DNS_LOOKUP_QUEUE_FULL;
+    }
+
+    res = mResolver;
+    idn = mIDN;
+    localDomain = mLocalDomains.GetEntry(aHostname);
+  }
+  if (!res) {
+    return NS_ERROR_OFFLINE;
+  }
+
+  nsCString hostname;
+  nsresult rv = PreprocessHostname(localDomain, aHostname, idn, hostname);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  uint16_t af =
+      (aType != RESOLVE_TYPE_DEFAULT) ? 0 : GetAFForLookup(hostname, aFlags);
+
+  res->CancelAsyncRequest(hostname, DNSResolverInfo::URL(aResolver), aType,
+                          aOriginAttributes, aFlags, af, aListener, aReason);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::AsyncResolve(const nsACString& aHostname,
+                           nsIDNSService::ResolveType aType, uint32_t flags,
+                           nsIDNSResolverInfo* aResolver,
+                           nsIDNSListener* listener, nsIEventTarget* target_,
+                           JS::HandleValue aOriginAttributes, JSContext* aCx,
+                           uint8_t aArgc, nsICancelable** result) {
+  OriginAttributes attrs;
+
+  if (aArgc == 1) {
+    if (!aOriginAttributes.isObject() || !attrs.Init(aCx, aOriginAttributes)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+
+  return AsyncResolveInternal(aHostname, aType, flags, aResolver, listener,
+                              target_, attrs, result);
+}
+
+NS_IMETHODIMP
+nsDNSService::AsyncResolveNative(const nsACString& aHostname,
+                                 nsIDNSService::ResolveType aType,
+                                 uint32_t flags, nsIDNSResolverInfo* aResolver,
+                                 nsIDNSListener* aListener,
+                                 nsIEventTarget* target_,
+                                 const OriginAttributes& aOriginAttributes,
+                                 nsICancelable** result) {
+  return AsyncResolveInternal(aHostname, aType, flags, aResolver, aListener,
+                              target_, aOriginAttributes, result);
+}
+
+NS_IMETHODIMP
+nsDNSService::NewTRRResolverInfo(const nsACString& aTrrURL,
+                                 nsIDNSResolverInfo** aResolver) {
+  RefPtr<DNSResolverInfo> res = new DNSResolverInfo(aTrrURL);
+  res.forget(aResolver);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::CancelAsyncResolve(const nsACString& aHostname,
+                                 nsIDNSService::ResolveType aType,
+                                 uint32_t aFlags, nsIDNSResolverInfo* aResolver,
+                                 nsIDNSListener* aListener, nsresult aReason,
+                                 JS::HandleValue aOriginAttributes,
+                                 JSContext* aCx, uint8_t aArgc) {
+  OriginAttributes attrs;
+
+  if (aArgc == 1) {
+    if (!aOriginAttributes.isObject() || !attrs.Init(aCx, aOriginAttributes)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+
+  return CancelAsyncResolveInternal(aHostname, aType, aFlags, aResolver,
+                                    aListener, aReason, attrs);
+}
+
+NS_IMETHODIMP
+nsDNSService::CancelAsyncResolveNative(
+    const nsACString& aHostname, nsIDNSService::ResolveType aType,
+    uint32_t aFlags, nsIDNSResolverInfo* aResolver, nsIDNSListener* aListener,
+    nsresult aReason, const OriginAttributes& aOriginAttributes) {
+  return CancelAsyncResolveInternal(aHostname, aType, aFlags, aResolver,
+                                    aListener, aReason, aOriginAttributes);
+}
+
+NS_IMETHODIMP
+nsDNSService::Resolve(const nsACString& aHostname, uint32_t flags,
+                      JS::HandleValue aOriginAttributes, JSContext* aCx,
+                      uint8_t aArgc, nsIDNSRecord** result) {
+  OriginAttributes attrs;
+
+  if (aArgc == 1) {
+    if (!aOriginAttributes.isObject() || !attrs.Init(aCx, aOriginAttributes)) {
+      return NS_ERROR_INVALID_ARG;
+    }
+  }
+
+  return ResolveNative(aHostname, flags, attrs, result);
+}
+
+NS_IMETHODIMP
+nsDNSService::ResolveNative(const nsACString& aHostname, uint32_t flags,
+                            const OriginAttributes& aOriginAttributes,
+                            nsIDNSRecord** result) {
+  // Synchronous resolution is not available on the main thread.
+  if (NS_IsMainThread()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  return ResolveInternal(aHostname, flags, aOriginAttributes, result);
+}
+
+nsresult nsDNSService::DeprecatedSyncResolve(
+    const nsACString& aHostname, uint32_t flags,
+    const OriginAttributes& aOriginAttributes, nsIDNSRecord** result) {
+  return ResolveInternal(aHostname, flags, aOriginAttributes, result);
+}
+
+nsresult nsDNSService::ResolveInternal(
+    const nsACString& aHostname, uint32_t flags,
+    const OriginAttributes& aOriginAttributes, nsIDNSRecord** result) {
+  // grab reference to global host resolver and IDN service.  beware
+  // simultaneous shutdown!!
+  RefPtr<nsHostResolver> res;
+  nsCOMPtr<nsIIDNService> idn;
+  bool localDomain = false;
+  {
+    MutexAutoLock lock(mLock);
+    res = mResolver;
+    idn = mIDN;
+    localDomain = mLocalDomains.GetEntry(aHostname);
+  }
+
+  if (mNotifyResolution) {
+    NS_DispatchToMainThread(new NotifyDNSResolution(aHostname));
+  }
+
+  NS_ENSURE_TRUE(res, NS_ERROR_OFFLINE);
+
+  nsCString hostname;
+  nsresult rv = PreprocessHostname(localDomain, aHostname, idn, hostname);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (GetOffline() &&
+      (!mOfflineLocalhost || !hostname.LowerCaseEqualsASCII("localhost"))) {
+    flags |= RESOLVE_OFFLINE;
+  }
+
+  if (DNSForbiddenByActiveProxy(aHostname, flags)) {
+    return NS_ERROR_UNKNOWN_PROXY_HOST;
+  }
+
+  //
+  // sync resolve: since the host resolver only works asynchronously, we need
+  // to use a mutex and a condvar to wait for the result.  however, since the
+  // result may be in the resolvers cache, we might get called back recursively
+  // on the same thread.  so, our mutex needs to be re-entrant.  in other words,
+  // we need to use a monitor! ;-)
+  //
+
+  PRMonitor* mon = PR_NewMonitor();
+  if (!mon) {
+    return NS_ERROR_OUT_OF_MEMORY;
+  }
+
+  PR_EnterMonitor(mon);
+  RefPtr<nsDNSSyncRequest> syncReq = new nsDNSSyncRequest(mon);
+
+  uint16_t af = GetAFForLookup(hostname, flags);
+
+  // TRR uses the main thread for the HTTPS channel to the DoH server.
+  // If this were to block the main thread while waiting for TRR it would
+  // likely cause a deadlock. Instead we intentionally choose to not use TRR
+  // for this.
+  if (NS_IsMainThread()) {
+    flags |= RESOLVE_DISABLE_TRR;
+  }
+
+  rv = res->ResolveHost(hostname, ""_ns, RESOLVE_TYPE_DEFAULT,
+                        aOriginAttributes, flags, af, syncReq);
+  if (NS_SUCCEEDED(rv)) {
+    // wait for result
+    while (!syncReq->mDone) {
+      PR_Wait(mon, PR_INTERVAL_NO_TIMEOUT);
+    }
+
+    if (NS_FAILED(syncReq->mStatus)) {
+      rv = syncReq->mStatus;
+    } else {
+      NS_ASSERTION(syncReq->mHostRecord, "no host record");
+      RefPtr<nsDNSRecord> rec = new nsDNSRecord(syncReq->mHostRecord);
+      rec.forget(result);
+    }
+  }
+
+  PR_ExitMonitor(mon);
+  PR_DestroyMonitor(mon);
+  return rv;
+}
+
+NS_IMETHODIMP
+nsDNSService::GetMyHostName(nsACString& result) {
+  char name[100];
+  if (PR_GetSystemInfo(PR_SI_HOSTNAME, name, sizeof(name)) == PR_SUCCESS) {
+    result = name;
+    return NS_OK;
+  }
+  return NS_ERROR_FAILURE;
+}
+
+NS_IMETHODIMP
+nsDNSService::Observe(nsISupports* subject, const char* topic,
+                      const char16_t* data) {
+  bool flushCache = false;
+  if (!strcmp(topic, NS_NETWORK_LINK_TOPIC)) {
+    nsAutoCString converted = NS_ConvertUTF16toUTF8(data);
+    if (mResolver && !strcmp(converted.get(), NS_NETWORK_LINK_DATA_CHANGED)) {
+      flushCache = true;
+    }
+  } else if (!strcmp(topic, "last-pb-context-exited")) {
+    flushCache = true;
+  } else if (!strcmp(topic, NS_PREFBRANCH_PREFCHANGE_TOPIC_ID)) {
+    ReadPrefs(NS_ConvertUTF16toUTF8(data).get());
+    NS_ENSURE_TRUE(mResolver, NS_ERROR_NOT_INITIALIZED);
+    if (mResolverPrefsUpdated && mResolver) {
+      mResolver->SetCacheLimits(mResCacheEntries, mResCacheExpiration,
+                                mResCacheGrace);
+    }
+  } else if (!strcmp(topic, NS_XPCOM_SHUTDOWN_OBSERVER_ID)) {
+    Shutdown();
+  }
+
+  if (flushCache && mResolver) {
+    mResolver->FlushCache(false);
+    return NS_OK;
+  }
+
+  return NS_OK;
+}
+
+uint16_t nsDNSService::GetAFForLookup(const nsACString& host, uint32_t flags) {
+  if (mDisableIPv6 || (flags & RESOLVE_DISABLE_IPV6)) {
+    return PR_AF_INET;
+  }
+
+  MutexAutoLock lock(mLock);
+
+  uint16_t af = PR_AF_UNSPEC;
+
+  if (!mIPv4OnlyDomains.IsEmpty()) {
+    const char *domain, *domainEnd, *end;
+    uint32_t hostLen, domainLen;
+
+    // see if host is in one of the IPv4-only domains
+    domain = mIPv4OnlyDomains.BeginReading();
+    domainEnd = mIPv4OnlyDomains.EndReading();
+
+    nsACString::const_iterator hostStart;
+    host.BeginReading(hostStart);
+    hostLen = host.Length();
+
+    do {
+      // skip any whitespace
+      while (*domain == ' ' || *domain == '\t') {
+        ++domain;
+      }
+
+      // find end of this domain in the string
+      end = strchr(domain, ',');
+      if (!end) {
+        end = domainEnd;
+      }
+
+      // to see if the hostname is in the domain, check if the domain
+      // matches the end of the hostname.
+      domainLen = end - domain;
+      if (domainLen && hostLen >= domainLen) {
+        const char* hostTail = hostStart.get() + hostLen - domainLen;
+        if (PL_strncasecmp(domain, hostTail, domainLen) == 0) {
+          // now, make sure either that the hostname is a direct match or
+          // that the hostname begins with a dot.
+          if (hostLen == domainLen || *hostTail == '.' ||
+              *(hostTail - 1) == '.') {
+            af = PR_AF_INET;
+            break;
+          }
+        }
+      }
+
+      domain = end + 1;
+    } while (*end);
+  }
+
+  if ((af != PR_AF_INET) && (flags & RESOLVE_DISABLE_IPV4)) {
+    af = PR_AF_INET6;
+  }
+
+  return af;
+}
+
+NS_IMETHODIMP
+nsDNSService::GetDNSCacheEntries(
+    nsTArray<mozilla::net::DNSCacheEntries>* args) {
+  NS_ENSURE_TRUE(mResolver, NS_ERROR_NOT_INITIALIZED);
+  mResolver->GetDNSCacheEntries(args);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::ClearCache(bool aTrrToo) {
+  NS_ENSURE_TRUE(mResolver, NS_ERROR_NOT_INITIALIZED);
+  mResolver->FlushCache(aTrrToo);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::ReloadParentalControlEnabled() {
+  if (mTrrService) {
+    mTrrService->mParentalControlEnabled =
+        TRRService::GetParentalControlEnabledInternal();
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::SetDetectedTrrURI(const nsACString& aURI) {
+  if (mTrrService) {
+    mTrrService->SetDetectedTrrURI(aURI);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::GetCurrentTrrURI(nsACString& aURI) {
+  if (mTrrService) {
+    return mTrrService->GetURI(aURI);
+  }
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::GetCurrentTrrMode(uint32_t* aMode) {
+  *aMode = 0;  // The default mode.
+  if (mTrrService) {
+    *aMode = mTrrService->Mode();
+  }
+  return NS_OK;
+}
+
+size_t nsDNSService::SizeOfIncludingThis(
+    mozilla::MallocSizeOf mallocSizeOf) const {
+  // Measurement of the following members may be added later if DMD finds it
+  // is worthwhile:
+  // - mIDN
+  // - mLock
+
+  size_t n = mallocSizeOf(this);
+  n += mResolver ? mResolver->SizeOfIncludingThis(mallocSizeOf) : 0;
+  n += mIPv4OnlyDomains.SizeOfExcludingThisIfUnshared(mallocSizeOf);
+  n += mLocalDomains.SizeOfExcludingThis(mallocSizeOf);
+  n += mFailedSVCDomainNames.ShallowSizeOfExcludingThis(mallocSizeOf);
+  for (auto iter = mFailedSVCDomainNames.ConstIter(); !iter.Done();
+       iter.Next()) {
+    n += iter.UserData()->ShallowSizeOfExcludingThis(mallocSizeOf);
+    for (const auto& name : *iter.UserData()) {
+      n += name.SizeOfExcludingThisIfUnshared(mallocSizeOf);
+    }
+  }
+  return n;
+}
+
+MOZ_DEFINE_MALLOC_SIZE_OF(DNSServiceMallocSizeOf)
+
+NS_IMETHODIMP
+nsDNSService::CollectReports(nsIHandleReportCallback* aHandleReport,
+                             nsISupports* aData, bool aAnonymize) {
+  MOZ_COLLECT_REPORT("explicit/network/dns-service", KIND_HEAP, UNITS_BYTES,
+                     SizeOfIncludingThis(DNSServiceMallocSizeOf),
+                     "Memory used for the DNS service.");
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::ReportFailedSVCDomainName(const nsACString& aOwnerName,
+                                        const nsACString& aSVCDomainName) {
+  MutexAutoLock lock(mLock);
+
+  nsTArray<nsCString>* failedList = mFailedSVCDomainNames.Get(aOwnerName);
+  if (!failedList) {
+    failedList = new nsTArray<nsCString>(1);
+    mFailedSVCDomainNames.Put(aOwnerName, failedList);
+  }
+
+  failedList->AppendElement(aSVCDomainName);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::IsSVCDomainNameFailed(const nsACString& aOwnerName,
+                                    const nsACString& aSVCDomainName,
+                                    bool* aResult) {
+  NS_ENSURE_ARG(aResult);
+
+  MutexAutoLock lock(mLock);
+  *aResult = false;
+  nsTArray<nsCString>* failedList = mFailedSVCDomainNames.Get(aOwnerName);
+  if (!failedList) {
+    return NS_OK;
+  }
+
+  *aResult = failedList->Contains(aSVCDomainName);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+nsDNSService::ResetExcludedSVCDomainName(const nsACString& aOwnerName) {
+  MutexAutoLock lock(mLock);
+  mFailedSVCDomainNames.Remove(aOwnerName);
+  return NS_OK;
+}