Bug 1748113 - Always load etc/hosts file in parent process, r=necko-reviewers,valentin

Differential Revision: https://phabricator.services.mozilla.com/D135097

netwerk/dns/PTRRService.ipdl

@@ -28,6 +28,7 @@ child:
   async ClearDNSCache(bool aTrrToo);
   async SetDetectedTrrURI(nsCString aURI);
   async SetDefaultTRRConnectionInfo(HttpConnectionInfoCloneArgs? aConnInfoArgs);
+  async UpdateEtcHosts(nsCString[] aHosts);
 };
 
 } //namespace net

netwerk/dns/TRRService.cpp

@@ -23,15 +23,10 @@
 #include "mozilla/Telemetry.h"
 #include "mozilla/TelemetryComms.h"
 #include "mozilla/Tokenizer.h"
-#include "mozilla/net/rust_helper.h"
 #include "mozilla/net/TRRServiceChild.h"
 // Put DNSLogging.h at the end to avoid LOG being overwritten by other headers.
 #include "DNSLogging.h"
 
-#if defined(XP_WIN) && !defined(__MINGW32__)
-#  include <shlobj_core.h>  // for SHGetSpecialFolderPathA
-#endif                      // XP_WIN
-
 static const char kOpenCaptivePortalLoginEvent[] = "captive-portal-login";
 static const char kClearPrivateData[] = "clear-private-data";
 static const char kPurge[] = "browser:purge-session-history";
@@ -432,48 +427,17 @@ void TRRService::AddEtcHosts(const nsTArray<nsCString>& aArray) {
 }
 
 void TRRService::ReadEtcHostsFile() {
-  if (!StaticPrefs::network_trr_exclude_etc_hosts()) {
+  if (!XRE_IsParentProcess()) {
     return;
   }
 
-  auto readHostsTask = []() {
-    MOZ_ASSERT(!NS_IsMainThread(), "Must not run on the main thread");
-#if defined(XP_WIN) && !defined(__MINGW32__)
-    // Inspired by libevent/evdns.c
-    // Windows is a little coy about where it puts its configuration
-    // files.  Sure, they're _usually_ in C:\windows\system32, but
-    // there's no reason in principle they couldn't be in
-    // W:\hoboken chicken emergency
-
-    nsCString path;
-    path.SetLength(MAX_PATH + 1);
-    if (!SHGetSpecialFolderPathA(NULL, path.BeginWriting(), CSIDL_SYSTEM,
-                                 false)) {
-      LOG(("Calling SHGetSpecialFolderPathA failed"));
-      return;
+  DoReadEtcHostsFile([](const nsTArray<nsCString>* aArray) -> bool {
+    RefPtr<TRRService> service(sTRRServicePtr);
+    if (service && aArray) {
+      service->AddEtcHosts(*aArray);
     }
-
-    path.SetLength(strlen(path.get()));
-    path.Append("\\drivers\\etc\\hosts");
-#elif defined(__MINGW32__)
-    nsAutoCString path("C:\\windows\\system32\\drivers\\etc\\hosts"_ns);
-#else
-    nsAutoCString path("/etc/hosts"_ns);
-#endif
-
-    LOG(("Reading hosts file at %s", path.get()));
-    rust_parse_etc_hosts(&path, [](const nsTArray<nsCString>* aArray) -> bool {
-      RefPtr<TRRService> service(sTRRServicePtr);
-      if (service && aArray) {
-        service->AddEtcHosts(*aArray);
-      }
-      return !!service;
-    });
-  };
-
-  Unused << NS_DispatchBackgroundTask(
-      NS_NewRunnableFunction("Read /etc/hosts file", readHostsTask),
-      NS_DISPATCH_EVENT_MAY_BLOCK);
+    return !!service;
+  });
 }
 
 void TRRService::GetURI(nsACString& result) {

netwerk/dns/TRRServiceBase.cpp

@@ -21,6 +21,10 @@
 // Put DNSLogging.h at the end to avoid LOG being overwritten by other headers.
 #include "DNSLogging.h"
 
+#if defined(XP_WIN) && !defined(__MINGW32__)
+#  include <shlobj_core.h>  // for SHGetSpecialFolderPathA
+#endif                      // XP_WIN
+
 namespace mozilla {
 namespace net {
 
@@ -339,5 +343,46 @@ void TRRServiceBase::UnregisterProxyChangeListener() {
   pps->RemoveProxyConfigCallback(this);
 }
 
+void TRRServiceBase::DoReadEtcHostsFile(ParsingCallback aCallback) {
+  MOZ_ASSERT(XRE_IsParentProcess());
+
+  if (!StaticPrefs::network_trr_exclude_etc_hosts()) {
+    return;
+  }
+
+  auto readHostsTask = [aCallback]() {
+    MOZ_ASSERT(!NS_IsMainThread(), "Must not run on the main thread");
+#if defined(XP_WIN) && !defined(__MINGW32__)
+    // Inspired by libevent/evdns.c
+    // Windows is a little coy about where it puts its configuration
+    // files.  Sure, they're _usually_ in C:\windows\system32, but
+    // there's no reason in principle they couldn't be in
+    // W:\hoboken chicken emergency
+
+    nsCString path;
+    path.SetLength(MAX_PATH + 1);
+    if (!SHGetSpecialFolderPathA(NULL, path.BeginWriting(), CSIDL_SYSTEM,
+                                 false)) {
+      LOG(("Calling SHGetSpecialFolderPathA failed"));
+      return;
+    }
+
+    path.SetLength(strlen(path.get()));
+    path.Append("\\drivers\\etc\\hosts");
+#elif defined(__MINGW32__)
+    nsAutoCString path("C:\\windows\\system32\\drivers\\etc\\hosts"_ns);
+#else
+    nsAutoCString path("/etc/hosts"_ns);
+#endif
+
+    LOG(("Reading hosts file at %s", path.get()));
+    rust_parse_etc_hosts(&path, aCallback);
+  };
+
+  Unused << NS_DispatchBackgroundTask(
+      NS_NewRunnableFunction("Read /etc/hosts file", readHostsTask),
+      NS_DISPATCH_EVENT_MAY_BLOCK);
+}
+
 }  // namespace net
 }  // namespace mozilla

netwerk/dns/TRRServiceBase.h

@@ -8,6 +8,7 @@
 
 #include "mozilla/Atomics.h"
 #include "mozilla/DataMutex.h"
+#include "mozilla/net/rust_helper.h"
 #include "nsString.h"
 #include "nsIDNSService.h"
 #include "nsIProtocolProxyService2.h"
@@ -53,7 +54,8 @@ class TRRServiceBase : public nsIProxyConfigChangedCallback {
   void OnTRRModeChange();
   void OnTRRURIChange();
 
-  virtual void ReadEtcHostsFile() {}
+  void DoReadEtcHostsFile(ParsingCallback aCallback);
+  virtual void ReadEtcHostsFile() = 0;
   // Called to create a connection info that will be used by TRRServiceChannel.
   // Note that when this function is called, mDefaultTRRConnectionInfo will be
   // set to null to invalidate the connection info.

netwerk/dns/TRRServiceChild.cpp

@@ -111,5 +111,11 @@ mozilla::ipc::IPCResult TRRServiceChild::RecvSetDefaultTRRConnectionInfo(
   return IPC_OK();
 }
 
+mozilla::ipc::IPCResult TRRServiceChild::RecvUpdateEtcHosts(
+    nsTArray<nsCString>&& aHosts) {
+  TRRService::Get()->AddEtcHosts(aHosts);
+  return IPC_OK();
+}
+
 }  // namespace net
 }  // namespace mozilla

netwerk/dns/TRRServiceChild.h

@@ -41,6 +41,7 @@ class TRRServiceChild : public PTRRServiceChild,
   mozilla::ipc::IPCResult RecvSetDetectedTrrURI(const nsCString& aURI);
   mozilla::ipc::IPCResult RecvSetDefaultTRRConnectionInfo(
       Maybe<HttpConnectionInfoCloneArgs>&& aArgs);
+  mozilla::ipc::IPCResult RecvUpdateEtcHosts(nsTArray<nsCString>&& aHosts);
 
  private:
   virtual ~TRRServiceChild();

netwerk/dns/TRRServiceParent.cpp

@@ -25,6 +25,8 @@
 namespace mozilla {
 namespace net {
 
+static Atomic<TRRServiceParent*> sTRRServiceParentPtr;
+
 static const char* gTRRUriCallbackPrefs[] = {
     "network.trr.uri",  "network.trr.default_provider_uri",
     "network.trr.mode", kRolloutURIPref,
@@ -68,8 +70,10 @@ void TRRServiceParent::Init() {
                                        gTRRUriCallbackPrefs, this);
   prefsChanged(nullptr);
 
-  Unused << socketParent->SendPTRRServiceConstructor(
-      this, captiveIsPassed, parentalControlEnabled, suffixList);
+  if (socketParent->SendPTRRServiceConstructor(
+          this, captiveIsPassed, parentalControlEnabled, suffixList)) {
+    sTRRServiceParentPtr = this;
+  }
 }
 
 NS_IMETHODIMP
@@ -168,6 +172,7 @@ void TRRServiceParent::prefsChanged(const char* aName) {
 }
 
 void TRRServiceParent::ActorDestroy(ActorDestroyReason why) {
+  sTRRServiceParentPtr = nullptr;
   Preferences::UnregisterPrefixCallbacks(TRRServiceParent::PrefsChanged,
                                          gTRRUriCallbackPrefs, this);
 }
@@ -208,5 +213,26 @@ mozilla::ipc::IPCResult TRRServiceParent::RecvSetConfirmationState(
   return IPC_OK();
 }
 
+void TRRServiceParent::ReadEtcHostsFile() {
+  if (!sTRRServiceParentPtr) {
+    return;
+  }
+
+  DoReadEtcHostsFile([](const nsTArray<nsCString>* aArray) -> bool {
+    RefPtr<TRRServiceParent> service(sTRRServiceParentPtr);
+    if (service && aArray) {
+      nsTArray<nsCString> hosts(aArray->Clone());
+      NS_DispatchToMainThread(NS_NewRunnableFunction(
+          "TRRServiceParent::ReadEtcHostsFile",
+          [service, hosts = std::move(hosts)]() mutable {
+            if (service->CanSend()) {
+              Unused << service->SendUpdateEtcHosts(hosts);
+            }
+          }));
+    }
+    return !!service;
+  });
+}
+
 }  // namespace net
 }  // namespace mozilla

netwerk/dns/TRRServiceParent.h

@@ -36,6 +36,7 @@ class TRRServiceParent : public TRRServiceBase,
   mozilla::ipc::IPCResult RecvInitTRRConnectionInfo();
   mozilla::ipc::IPCResult RecvSetConfirmationState(uint32_t aNewState);
   uint32_t GetConfirmationState() { return mConfirmationState; }
+  virtual void ReadEtcHostsFile() override;
 
  private:
   virtual ~TRRServiceParent();