[6329][Web]: Fixed abort race condition in WebConnection.ReadDone().

ReadDone() now passes the 'WebConnectionData' instance to GetResponse()
and 'readState' has been moved into 'WebConnectionData'.

Abort() can now reset 'Data' while ReadDone() still uses the old
instance, but learns about the abort request from 'data.ReadState'.

mcs/class/System/System.Net/WebConnection.cs

@@ -46,7 +46,8 @@ namespace System.Net
 		None,
 		Status,
 		Headers,
-		Content
+		Content,
+		Aborted
 	}
 
 	class WebConnection
@@ -62,7 +63,6 @@ namespace System.Net
 		static AsyncCallback readDoneDelegate = new AsyncCallback (ReadDone);
 		EventHandler abortHandler;
 		AbortHelper abortHelper;
-		ReadState readState;
 		internal WebConnectionData Data;
 		bool chunkedRead;
 		ChunkStream chunkStream;
@@ -108,7 +108,6 @@ namespace System.Net
 		{
 			this.sPoint = sPoint;
 			buffer = new byte [4096];
-			readState = ReadState.None;
 			Data = new WebConnectionData ();
 			initConn = new WaitCallback (state => {
 				try {
@@ -493,7 +492,7 @@ namespace System.Net
 		
 		static void ReadDone (IAsyncResult result)
 		{
-			WebConnection cnc = (WebConnection) result.AsyncState;
+			WebConnection cnc = (WebConnection)result.AsyncState;
 			WebConnectionData data = cnc.Data;
 			Stream ns = cnc.nstream;
 			if (ns == null) {
@@ -526,10 +525,10 @@ namespace System.Net
 
 			int pos = -1;
 			nread += cnc.position;
-			if (cnc.readState == ReadState.None) { 
+			if (data.ReadState == ReadState.None) { 
 				Exception exc = null;
 				try {
-					pos = cnc.GetResponse (cnc.buffer, nread);
+					pos = GetResponse (data, cnc.sPoint, cnc.buffer, nread);
 				} catch (Exception e) {
 					exc = e;
 				}
@@ -540,14 +539,19 @@ namespace System.Net
 				}
 			}
 
-			if (cnc.readState != ReadState.Content) {
+			if (data.ReadState == ReadState.Aborted) {
+				cnc.HandleError (WebExceptionStatus.RequestCanceled, null, "ReadDone");
+				return;
+			}
+
+			if (data.ReadState != ReadState.Content) {
 				int est = nread * 2;
 				int max = (est < cnc.buffer.Length) ? cnc.buffer.Length : est;
 				byte [] newBuffer = new byte [max];
 				Buffer.BlockCopy (cnc.buffer, 0, newBuffer, 0, nread);
 				cnc.buffer = newBuffer;
 				cnc.position = nread;
-				cnc.readState = ReadState.None;
+				data.ReadState = ReadState.None;
 				InitRead (cnc);
 				return;
 			}
@@ -624,7 +628,8 @@ namespace System.Net
 			}
 		}
 		
-		int GetResponse (byte [] buffer, int max)
+		static int GetResponse (WebConnectionData data, ServicePoint sPoint,
+		                        byte [] buffer, int max)
 		{
 			int pos = 0;
 			string line = null;
@@ -632,7 +637,10 @@ namespace System.Net
 			bool isContinue = false;
 			bool emptyFirstLine = false;
 			do {
-				if (readState == ReadState.None) {
+				if (data.ReadState == ReadState.Aborted)
+					return -1;
+
+				if (data.ReadState == ReadState.None) {
 					lineok = ReadLine (buffer, ref pos, max, ref line);
 					if (!lineok)
 						return 0;
@@ -642,35 +650,34 @@ namespace System.Net
 						continue;
 					}
 					emptyFirstLine = false;
-
-					readState = ReadState.Status;
+					data.ReadState = ReadState.Status;
 
 					string [] parts = line.Split (' ');
 					if (parts.Length < 2)
 						return -1;
 
 					if (String.Compare (parts [0], "HTTP/1.1", true) == 0) {
-						Data.Version = HttpVersion.Version11;
+						data.Version = HttpVersion.Version11;
 						sPoint.SetVersion (HttpVersion.Version11);
 					} else {
-						Data.Version = HttpVersion.Version10;
+						data.Version = HttpVersion.Version10;
 						sPoint.SetVersion (HttpVersion.Version10);
 					}
 
-					Data.StatusCode = (int) UInt32.Parse (parts [1]);
+					data.StatusCode = (int) UInt32.Parse (parts [1]);
 					if (parts.Length >= 3)
-						Data.StatusDescription = String.Join (" ", parts, 2, parts.Length - 2);
+						data.StatusDescription = String.Join (" ", parts, 2, parts.Length - 2);
 					else
-						Data.StatusDescription = "";
+						data.StatusDescription = "";
 
 					if (pos >= max)
 						return pos;
 				}
 
 				emptyFirstLine = false;
-				if (readState == ReadState.Status) {
-					readState = ReadState.Headers;
-					Data.Headers = new WebHeaderCollection ();
+				if (data.ReadState == ReadState.Status) {
+					data.ReadState = ReadState.Headers;
+					data.Headers = new WebHeaderCollection ();
 					ArrayList headers = new ArrayList ();
 					bool finished = false;
 					while (!finished) {
@@ -699,25 +706,25 @@ namespace System.Net
 						return 0;
 
 					foreach (string s in headers)
-						Data.Headers.SetInternal (s);
+						data.Headers.SetInternal (s);
 
-					if (Data.StatusCode == (int) HttpStatusCode.Continue) {
+					if (data.StatusCode == (int) HttpStatusCode.Continue) {
 						sPoint.SendContinue = true;
 						if (pos >= max)
 							return pos;
 
-						if (Data.request.ExpectContinue) {
-							Data.request.DoContinueDelegate (Data.StatusCode, Data.Headers);
+						if (data.request.ExpectContinue) {
+							data.request.DoContinueDelegate (data.StatusCode, data.Headers);
 							// Prevent double calls when getting the
 							// headers in several packets.
-							Data.request.ExpectContinue = false;
+							data.request.ExpectContinue = false;
 						}
 
-						readState = ReadState.None;
+						data.ReadState = ReadState.None;
 						isContinue = true;
 					}
 					else {
-						readState = ReadState.Content;
+						data.ReadState = ReadState.Content;
 						return pos;
 					}
 				}
@@ -764,7 +771,6 @@ namespace System.Net
 				return;
 			}
 
-			readState = ReadState.None;
 			request.SetWriteStream (new WebConnectionStream (this, request));
 		}
 		
@@ -1160,6 +1166,11 @@ namespace System.Net
 
 				if (ntlm_authenticated)
 					ResetNtlm ();
+				if (Data != null) {
+					lock (Data) {
+						Data.ReadState = ReadState.Aborted;
+					}
+				}
 				busy = false;
 				Data = new WebConnectionData ();
 				if (sendNext)

mcs/class/System/System.Net/WebConnectionData.cs

@@ -41,9 +41,11 @@ namespace System.Net
 		public Version Version;
 		public Stream stream;
 		public string[] Challenge;
+		ReadState _readState;
 
 		public WebConnectionData ()
 		{
+			_readState = ReadState.None;
 		}
 
 		public WebConnectionData (HttpWebRequest request)
@@ -59,6 +61,19 @@ namespace System.Net
 				_request = value;
 			}
 		}
+
+		public ReadState ReadState {
+			get {
+				return _readState;
+			}
+			set {
+				lock (this) {
+					if ((_readState == ReadState.Aborted) && (value != ReadState.Aborted))
+						throw new WebException ("Aborted", WebExceptionStatus.RequestCanceled);
+					_readState = value;
+				}
+			}
+		}
 	}
 }