Bug 1450893 - Add way to clear DNS cache r=dragana

Differential Revision: https://phabricator.services.mozilla.com/D24300

--HG--
extra : moz-landing-system : lando

netwerk/dns/ChildDNSService.cpp

@@ -285,6 +285,9 @@ ChildDNSService::GetDNSCacheEntries(
   return NS_ERROR_NOT_AVAILABLE;
 }
 
+NS_IMETHODIMP
+ChildDNSService::ClearCache(bool aTrrToo) { return NS_ERROR_NOT_AVAILABLE; }
+
 NS_IMETHODIMP
 ChildDNSService::GetMyHostName(nsACString &result) {
   // TODO: get value from parent during PNecko construction?

netwerk/dns/nsDNSService2.cpp

@@ -1131,7 +1131,7 @@ nsDNSService::Observe(nsISupports *subject, const char *topic,
   }
 
   if (flushCache) {
-    mResolver->FlushCache();
+    mResolver->FlushCache(false);
     return NS_OK;
   }
 
@@ -1198,6 +1198,12 @@ nsDNSService::GetDNSCacheEntries(
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDNSService::ClearCache(bool aTrrToo) {
+  mResolver->FlushCache(aTrrToo);
+  return NS_OK;
+}
+
 size_t nsDNSService::SizeOfIncludingThis(
     mozilla::MallocSizeOf mallocSizeOf) const {
   // Measurement of the following members may be added later if DMD finds it

netwerk/dns/nsHostResolver.cpp

@@ -385,10 +385,10 @@ void AddrHostRecord::Cancel() {
 
 // Returns true if the entry can be removed, or false if it should be left.
 // Sets mResolveAgain true for entries being resolved right now.
-bool AddrHostRecord::RemoveOrRefresh() {
+bool AddrHostRecord::RemoveOrRefresh(bool aTrrToo) {
   // no need to flush TRRed names, they're not resolved "locally"
   MutexAutoLock lock(addr_info_lock);
-  if (addr_info && addr_info->IsTRR()) {
+  if (addr_info && !aTrrToo && addr_info->IsTRR()) {
     return false;
   }
   if (mNative) {
@@ -715,7 +715,7 @@ void nsHostResolver::ClearPendingQueue(
 // cache that have 'Resolve' set true but not 'onQueue' are being resolved
 // right now, so we need to mark them to get re-resolved on completion!
 
-void nsHostResolver::FlushCache() {
+void nsHostResolver::FlushCache(bool aTrrToo) {
   MutexAutoLock lock(mLock);
   mEvictionQSize = 0;
 
@@ -738,7 +738,7 @@ void nsHostResolver::FlushCache() {
     if (record->IsAddrRecord()) {
       RefPtr<AddrHostRecord> addrRec = do_QueryObject(record);
       MOZ_ASSERT(addrRec);
-      if (addrRec->RemoveOrRefresh()) {
+      if (addrRec->RemoveOrRefresh(aTrrToo)) {
         if (record->isInList()) {
           record->remove();
         }

netwerk/dns/nsHostResolver.h

@@ -204,8 +204,8 @@ class AddrHostRecord final : public nsHostRecord {
 
   void Cancel() override;
 
-  bool RemoveOrRefresh();  // Mark records currently being resolved as needed
-                           // to resolve again.
+  bool RemoveOrRefresh(bool aTrrToo);  // Mark records currently being resolved
+                                       // as needed to resolve again.
 
   void ResolveComplete();
 
@@ -475,7 +475,7 @@ class nsHostResolver : public nsISupports, public AHostResolver {
   /**
    * Flush the DNS cache.
    */
-  void FlushCache();
+  void FlushCache(bool aTrrToo);
 
   LookupStatus CompleteLookup(nsHostRecord *, nsresult,
                               mozilla::net::AddrInfo *, bool pb,

netwerk/dns/nsIDNSService.idl

@@ -212,6 +212,17 @@ interface nsIDNSService : nsISupports
      */
     [noscript] void getDNSCacheEntries(in EntriesArray args);
 
+
+    /**
+     * Clears the DNS cache.
+     * @param aTrrToo
+     *        If true we will clear TRR cached entries too. Since these
+     *        are resolved remotely it's not necessary to clear them when
+     *        the network status changes, but it's sometimes useful to do so
+     *        for tests or other situations.
+     */
+    void clearCache(in boolean aTrrToo);
+
     /**
      * @return the hostname of the operating system.
      */