Bug 1528352: Logging improvements in nsUDPSocket, and handle negative returns from PR_RecvFrom properly. r=mayhemer

Differential Revision: https://phabricator.services.mozilla.com/D20565

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

netwerk/base/nsUDPSocket.cpp

@@ -270,6 +270,9 @@ void nsUDPSocket::OnMsgAttach() {
 
   // if we hit an error while trying to attach then bail...
   if (NS_FAILED(mCondition)) {
+    UDPSOCKET_LOG(("nsUDPSocket::OnMsgAttach: TryAttach FAILED err=0x%" PRIx32
+                   " [this=%p]\n",
+                   static_cast<uint32_t>(mCondition), this));
     NS_ASSERTION(!mAttached, "should not be attached already");
     OnSocketDetached(mFD);
   }
@@ -383,6 +386,8 @@ UDPMessageProxy::GetOutputStream(nsIOutputStream** aOutputStream) {
 //-----------------------------------------------------------------------------
 
 void nsUDPSocket::OnSocketReady(PRFileDesc* fd, int16_t outFlags) {
+  UDPSOCKET_LOG(
+      ("nsUDPSocket::OnSocketReady: flags=%d [this=%p]\n", outFlags, this));
   NS_ASSERTION(NS_SUCCEEDED(mCondition), "oops");
   NS_ASSERTION(mFD == fd, "wrong file descriptor");
   NS_ASSERTION(outFlags != -1, "unexpected timeout condition reached");
@@ -394,16 +399,24 @@ void nsUDPSocket::OnSocketReady(PRFileDesc* fd, int16_t outFlags) {
   }
 
   PRNetAddr prClientAddr;
-  uint32_t count;
+  int32_t count;
   // Bug 1252755 - use 9216 bytes to allign with nICEr and transportlayer to
   // support the maximum size of jumbo frames
   char buff[9216];
   count = PR_RecvFrom(mFD, buff, sizeof(buff), 0, &prClientAddr,
                       PR_INTERVAL_NO_WAIT);
+  if (count <= 0) {
+    UDPSOCKET_LOG(
+        ("nsUDPSocket::OnSocketReady: PR_RecvFrom returned no data [this=%p]\n",
+         this));
+    return;
+  }
   mByteReadCount += count;
 
   FallibleTArray<uint8_t> data;
   if (!data.AppendElements(buff, count, fallible)) {
+    UDPSOCKET_LOG((
+        "nsUDPSocket::OnSocketReady: AppendElements FAILED [this=%p]\n", this));
     mCondition = NS_ERROR_UNEXPECTED;
     return;
   }
@@ -437,6 +450,7 @@ void nsUDPSocket::OnSocketReady(PRFileDesc* fd, int16_t outFlags) {
 }
 
 void nsUDPSocket::OnSocketDetached(PRFileDesc* fd) {
+  UDPSOCKET_LOG(("nsUDPSocket::OnSocketDetached [this=%p]\n", this));
   // force a failure condition if none set; maybe the STS is shutting down :-/
   if (NS_SUCCEEDED(mCondition)) mCondition = NS_ERROR_ABORT;