bug 857291 - fix 807678 regression of DNS::GetCanonicalName r=josh

netwerk/dns/DNS.cpp

@@ -176,11 +176,19 @@ NetAddrElement::~NetAddrElement()
 }
 
 AddrInfo::AddrInfo(const char *host, const PRAddrInfo *prAddrInfo,
-                   bool disableIPv4)
+                   bool disableIPv4, const char *cname)
 {
   size_t hostlen = strlen(host);
   mHostName = static_cast<char*>(moz_xmalloc(hostlen + 1));
   memcpy(mHostName, host, hostlen + 1);
+  if (cname) {
+      size_t cnameLen = strlen(cname);
+      mCanonicalName = static_cast<char*>(moz_xmalloc(cnameLen + 1));
+      memcpy(mCanonicalName, cname, cnameLen + 1);
+  }
+  else {
+      mCanonicalName = nullptr;
+  }
 
   PRNetAddr tmpAddr;
   void *iter = nullptr;
@@ -200,6 +208,7 @@ AddrInfo::~AddrInfo()
     delete addrElement;
   }
   moz_free(mHostName);
+  moz_free(mCanonicalName);
 }
 
 } // namespace dns

netwerk/dns/DNS.h

@@ -121,10 +121,12 @@ public:
 
 class AddrInfo {
 public:
-  AddrInfo(const char *host, const PRAddrInfo *prAddrInfo, bool disableIPv4);
+  AddrInfo(const char *host, const PRAddrInfo *prAddrInfo, bool disableIPv4,
+           const char *cname);
   ~AddrInfo();
 
   char *mHostName;
+  char *mCanonicalName;
   LinkedList<NetAddrElement> mAddresses;
 };
 

netwerk/dns/nsDNSService2.cpp

@@ -83,7 +83,9 @@ nsDNSRecord::GetCanonicalName(nsACString &result)
     {
         MutexAutoLock lock(mHostRecord->addr_info_lock);
         if (mHostRecord->addr_info)
-            cname = mHostRecord->addr_info->mHostName;
+            cname = mHostRecord->addr_info->mCanonicalName ?
+                mHostRecord->addr_info->mCanonicalName :
+                mHostRecord->addr_info->mHostName;
         else
             cname = mHostRecord->host;
         result.Assign(cname);

netwerk/dns/nsHostResolver.cpp

@@ -997,7 +997,10 @@ nsHostResolver::ThreadFunc(void *arg)
         nsresult status;
         AddrInfo *ai = nullptr;
         if (prai) {
-            ai = new AddrInfo(rec->host, prai, disableIPv4);
+            const char *cname = nullptr;
+            if (rec->flags & RES_CANON_NAME)
+                cname = PR_GetCanonNameFromAddrInfo(prai);
+            ai = new AddrInfo(rec->host, prai, disableIPv4, cname);
             PR_FreeAddrInfo(prai);
             if (ai->mAddresses.isEmpty()) {
                 delete ai;