[wasm][debugger] Prevent crash on disconnect of client (#18107)

1 files changed, 34 insertions, 14 deletions

diff --git a/sdks/wasm/Mono.WebAssembly.DebuggerProxy/WsProxy.cs b/sdks/wasm/Mono.WebAssembly.DebuggerProxy/WsProxy.cs
index 3dc71059f5d..3d90be7b03b 100644
--- a/sdks/wasm/Mono.WebAssembly.DebuggerProxy/WsProxy.cs
+++ b/sdks/wasm/Mono.WebAssembly.DebuggerProxy/WsProxy.cs
@@ -97,6 +97,7 @@ namespace WsProxy {
 
 	public class WsProxy {
 		TaskCompletionSource<bool> side_exception = new TaskCompletionSource<bool> ();
+		TaskCompletionSource<bool> client_initiated_close = new TaskCompletionSource<bool> ();
 		List<(int, TaskCompletionSource<Result>)> pending_cmds = new List<(int, TaskCompletionSource<Result>)> ();
 		ClientWebSocket browser;
 		WebSocket ide;
@@ -119,8 +120,16 @@ namespace WsProxy {
 			byte [] buff = new byte [4000];
 			var mem = new MemoryStream ();
 			while (true) {
+
+				if (socket.State != WebSocketState.Open) {
+					Console.WriteLine ($"WSProxy: Socket is no longer open.");
+					client_initiated_close.TrySetResult (true);
+					return null;
+				}
+
 				var result = await socket.ReceiveAsync (new ArraySegment<byte> (buff), token);
 				if (result.MessageType == WebSocketMessageType.Close) {
+					client_initiated_close.TrySetResult (true);
 					return null;
 				}
 
@@ -199,9 +208,10 @@ namespace WsProxy {
 
 		void ProcessIdeMessage (string msg, CancellationToken token)
 		{
-			var res = JObject.Parse (msg);
-
-			pending_ops.Add (OnCommand (res ["id"].Value<int> (), res ["method"].Value<string> (), res ["params"] as JObject, token));
+			if (!string.IsNullOrEmpty (msg)) {
+				var res = JObject.Parse (msg);
+				pending_ops.Add (OnCommand (res ["id"].Value<int> (), res ["method"].Value<string> (), res ["params"] as JObject, token));
+			}
 		}
 
 		internal async Task<Result> SendCommand (string method, JObject args, CancellationToken token) {
@@ -255,24 +265,25 @@ namespace WsProxy {
 			Send (this.ide, o, token);
 		}
 
-		 // , HttpContext context)
-		public async Task Run (Uri browserUri, WebSocket ideSocket) 
+		// , HttpContext context)
+		public async Task Run (Uri browserUri, WebSocket ideSocket)
 		{
-			Debug ("wsproxy start");
+			Debug ($"WsProxy Starting on {browserUri}");
 			using (this.ide = ideSocket) {
-				Debug ("ide connected");
+				Debug ($"WsProxy: IDE waiting for connection on {browserUri}");
 				queues.Add (new WsQueue (this.ide));
 				using (this.browser = new ClientWebSocket ()) {
 					this.browser.Options.KeepAliveInterval = Timeout.InfiniteTimeSpan;
 					await this.browser.ConnectAsync (browserUri, CancellationToken.None);
 					queues.Add (new WsQueue (this.browser));
 
-					Debug ("client connected");
+					Debug ($"WsProxy: Client connected on {browserUri}");
 					var x = new CancellationTokenSource ();
 
 					pending_ops.Add (ReadOne (browser, x.Token));
 					pending_ops.Add (ReadOne (ide, x.Token));
 					pending_ops.Add (side_exception.Task);
+					pending_ops.Add (client_initiated_close.Task);
 
 					try {
 						while (!x.IsCancellationRequested) {
@@ -280,15 +291,23 @@ namespace WsProxy {
 							//Console.WriteLine ("pump {0} {1}", task, pending_ops.IndexOf (task));
 							if (task == pending_ops [0]) {
 								var msg = ((Task<string>)task).Result;
-								pending_ops [0] = ReadOne (browser, x.Token); //queue next read
-								ProcessBrowserMessage (msg, x.Token);
+								if (msg != null) {
+									pending_ops [0] = ReadOne (browser, x.Token); //queue next read
+									ProcessBrowserMessage (msg, x.Token);
+								}
 							} else if (task == pending_ops [1]) {
 								var msg = ((Task<string>)task).Result;
-								pending_ops [1] = ReadOne (ide, x.Token); //queue next read
-								ProcessIdeMessage (msg, x.Token);
+								if (msg != null) {
+									pending_ops [1] = ReadOne (ide, x.Token); //queue next read
+									ProcessIdeMessage (msg, x.Token);
+								}
 							} else if (task == pending_ops [2]) {
 								var res = ((Task<bool>)task).Result;
 								throw new Exception ("side task must always complete with an exception, what's going on???");
+							} else if (task == pending_ops [3]) {
+								var res = ((Task<bool>)task).Result;
+								Debug ($"WsProxy: Client initiated close from {browserUri}");
+								x.Cancel ();
 							} else {
 								//must be a background task
 								pending_ops.Remove (task);
@@ -301,10 +320,11 @@ namespace WsProxy {
 							}
 						}
 					} catch (Exception e) {
-						Debug ($"got exception {e}");
+						Debug ($"WsProxy::Run: Exception {e}");
 						//throw;
 					} finally {
-						x.Cancel ();
+						if (!x.IsCancellationRequested)
+							x.Cancel ();
 					}
 				}
 			}