Work around for a Firefox bug

Firefox won't fire EventSource open event until it receives some data. The workaround is to send an empty comment when starting ServerSentEvent transport.

Fixes: #352

samples/ChatSample/Views/Home/Index.cshtml

@@ -14,26 +14,45 @@
 </div>
 <script src="lib/signalr-client/signalr-client.js"></script>
 <script>
+let transportType = signalR.TransportType[getParameterByName('transport')] || signalR.TransportType.WebSockets;
 let connection = new signalR.HubConnection(`http://${document.location.host}/chat`, 'formatType=json&format=text');
 
-connection.on('Send', function (message) {
+connection.on('Send', message => appendLine(message));
-    var child = document.createElement('li');
+connection.onClosed = e => {
-    child.innerText = message;
+    if (e) {
-    document.getElementById('messages').appendChild(child);
+        appendLine('Connection closed with error: ' + e, 'red');
-});
+    }
+    else {
+        appendLine('Disconnected', 'green');
+    }
+};
 
-connection.start();
+connection.start(transportType).catch(err => appendLine(err, 'red'));
 
 document.getElementById('sendmessage').addEventListener('submit', event => {
     let data = document.getElementById('new-message').value;
-
+    connection.invoke('Send', data).catch(err => appendLine(err, 'red'));
-    connection.invoke('Send', data).catch(err => {
-        var child = document.createElement('li');
-        child.style.color = 'red';
-        child.innerText = err;
-        document.getElementById('messages').appendChild(child);
-    });
-
     event.preventDefault();
 });
+
+function appendLine(line, color) {
+    let child = document.createElement('li');
+    if (color) {
+        child.style.color = color;
+    }
+    child.innerText = line;
+    document.getElementById('messages').appendChild(child);
+}
+
+function getParameterByName(name, url) {
+    if (!url) {
+        url = window.location.href;
+    }
+    name = name.replace(/[\[\]]/g, "\\$&");
+    var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
+        results = regex.exec(url);
+    if (!results) return null;
+    if (!results[2]) return '';
+    return decodeURIComponent(results[2].replace(/\+/g, " "));
+}
 </script>

src/Microsoft.AspNetCore.Sockets.Common/Internal/Formatters/ServerSentEventsMessageParser.cs

@@ -13,6 +13,7 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
     {
         private const byte ByteCR = (byte)'\r';
         private const byte ByteLF = (byte)'\n';
+        private const byte ByteColon = (byte)':';
         private const byte ByteT = (byte)'T';
         private const byte ByteB = (byte)'B';
         private const byte ByteC = (byte)'C';
@@ -38,7 +39,6 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
 
             while (!reader.End)
             {
-
                 if (ReadCursorOperations.Seek(start, end, out var lineEnd, ByteLF) == -1)
                 {
                     // For the case of  data: Foo\r\n\r\<Anytine except \n>
@@ -63,6 +63,14 @@ namespace Microsoft.AspNetCore.Sockets.Internal.Formatters
                     throw new FormatException("There was an error in the frame format");
                 }
 
+                // Skip comments
+                if (line[0] == ByteColon)
+                {
+                    start = lineEnd;
+                    consumed = lineEnd;
+                    continue;
+                }
+
                 if (IsMessageEnd(line))
                 {
                     _internalParserState = InternalParseState.ReadEndOfMessage;

src/Microsoft.AspNetCore.Sockets/Transports/ServerSentEventsTransport.cs

@@ -37,6 +37,9 @@ namespace Microsoft.AspNetCore.Sockets.Transports
 
             context.Response.Headers["Content-Encoding"] = "identity";
 
+            // Workaround for a Firefox bug where EventSource won't fire the open event
+            // until it receives some data
+            await context.Response.WriteAsync(":\r\n");
             await context.Response.Body.FlushAsync();
 
             var pipe = context.Response.Body.AsPipelineWriter();

test/Microsoft.AspNetCore.Sockets.Common.Tests/Internal/Formatters/ServerSentEventsParserTests.cs

@@ -16,14 +16,20 @@ namespace Microsoft.AspNetCore.Sockets.Common.Tests.Internal.Formatters
         [Theory]
         [InlineData("data: T\r\n\r\n", "", MessageType.Text)]
         [InlineData("data: B\r\n\r\n", "", MessageType.Binary)]
+        [InlineData("data: T\r\n\r\n:\r\n", "", MessageType.Text)]
+        [InlineData("data: T\r\n\r\n:comment\r\n", "", MessageType.Text)]
         [InlineData("data: T\r\ndata: \r\r\n\r\n", "\r", MessageType.Text)]
+        [InlineData("data: T\r\n:comment\r\ndata: \r\r\n\r\n", "\r", MessageType.Text)]
         [InlineData("data: T\r\ndata: A\rB\r\n\r\n", "A\rB", MessageType.Text)]
         [InlineData("data: T\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
         [InlineData("data: T\r\ndata: Hello, World\r\n\r\ndata: ", "Hello, World", MessageType.Text)]
+        [InlineData("data: T\r\ndata: Hello, World\r\n\r\n:comment\r\ndata: ", "Hello, World", MessageType.Text)]
+        [InlineData("data: T\r\ndata: Hello, World\r\n\r\n:comment", "Hello, World", MessageType.Text)]
+        [InlineData("data: T\r\ndata: Hello, World\r\n\r\n:comment\r\n", "Hello, World", MessageType.Text)]
+        [InlineData("data: T\r\ndata: Hello, World\r\n:comment\r\n\r\n", "Hello, World", MessageType.Text)]
         [InlineData("data: B\r\ndata: SGVsbG8sIFdvcmxk\r\n\r\n", "Hello, World", MessageType.Binary)]
         [InlineData("data: B\r\ndata: SGVsbG8g\r\ndata: V29ybGQ=\r\n\r\n", "Hello World", MessageType.Binary)]
-    public void ParseSSEMessageSuccessCases(string encodedMessage, string expectedMessage, MessageType messageType)
+        public void ParseSSEMessageSuccessCases(string encodedMessage, string expectedMessage, MessageType messageType)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
             var readableBuffer = ReadableBuffer.Create(buffer);
@@ -68,6 +74,9 @@ namespace Microsoft.AspNetCore.Sockets.Common.Tests.Internal.Formatters
 
         [Theory]
         [InlineData("")]
+        [InlineData(":")]
+        [InlineData(":comment")]
+        [InlineData(":comment\r\n")]
         [InlineData("data:")]
         [InlineData("data: \r")]
         [InlineData("data: T\r\nda")]
@@ -77,6 +86,10 @@ namespace Microsoft.AspNetCore.Sockets.Common.Tests.Internal.Formatters
         [InlineData("data: T\r\ndata: Hello, World\r\n")]
         [InlineData("data: T\r\ndata: Hello, World\r\n\r")]
         [InlineData("data: B\r\ndata: SGVsbG8sIFd")]
+        [InlineData(":\r\ndata:")]
+        [InlineData("data: T\r\n:\r\n")]
+        [InlineData("data: T\r\n:\r\ndata:")]
+        [InlineData("data: T\r\ndata: Hello, World\r\n:comment")]
         public void ParseSSEMessageIncompleteParseResult(string encodedMessage)
         {
             var buffer = Encoding.UTF8.GetBytes(encodedMessage);
@@ -89,40 +102,47 @@ namespace Microsoft.AspNetCore.Sockets.Common.Tests.Internal.Formatters
         }
 
         [Theory]
-        [InlineData("d", "ata: T\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "d", "ata: T\r\ndata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T", "\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T", "\r\ndata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r", "\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r", "\ndata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\n", "data: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r\n", "data: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\nd", "ata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r\nd", "ata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\ndata: ", "Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r\ndata: ", "Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\ndata: Hello, World", "\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r\ndata: Hello, World", "\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T\r\ndata: Hello, World\r\n", "\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: T\r\ndata: Hello, World\r\n", "\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: T", "\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: ", "T\r\ndata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: ", "T\r\ndata: Hello, World\r\n\r\n", "Hello, World", MessageType.Text)]
+        [InlineData(new[] { ":", "comment", "\r\n", "d", "ata: T\r\ndata: Hello, World\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        [InlineData("data: B\r\ndata: SGVs", "bG8sIFdvcmxk\r\n\r\n", "Hello, World", MessageType.Binary)]
+        [InlineData(new[] { "data: T\r\n", ":comment", "\r\n", "data: Hello, World", "\r\n\r\n" }, "Hello, World", MessageType.Text)]
-        public async Task ParseMessageAcrossMultipleReadsSuccess(string encodedMessagePart1, string encodedMessagePart2, string expectedMessage, MessageType expectedMessageType)
+        [InlineData(new[] { "data: T\r\ndata: Hello, World\r\n", ":comment\r\n", "\r\n" }, "Hello, World", MessageType.Text)]
+        [InlineData(new[] { "data: B\r\ndata: SGVs", "bG8sIFdvcmxk\r\n\r\n" }, "Hello, World", MessageType.Binary)]
+        public async Task ParseMessageAcrossMultipleReadsSuccess(string[] messageParts, string expectedMessage, MessageType expectedMessageType)
         {
             using (var pipeFactory = new PipeFactory())
             {
+                var parser = new ServerSentEventsMessageParser();
                 var pipe = pipeFactory.Create();
 
-                // Read the first part of the message
+                Message message = default(Message);
-                await pipe.Writer.WriteAsync(Encoding.UTF8.GetBytes(encodedMessagePart1));
+                ReadCursor consumed = default(ReadCursor), examined = default(ReadCursor);
 
-                var result = await pipe.Reader.ReadAsync();
+                for (var i = 0; i < messageParts.Length; i++)
-                var parser = new ServerSentEventsMessageParser();
+                {
+                    var messagePart = messageParts[i];
+                    await pipe.Writer.WriteAsync(Encoding.UTF8.GetBytes(messagePart));
+                    var result = await pipe.Reader.ReadAsync();
 
-                var parseResult = parser.ParseMessage(result.Buffer, out var consumed, out var examined, out Message message);
+                    var parseResult = parser.ParseMessage(result.Buffer, out consumed, out examined, out message);
-                Assert.Equal(ServerSentEventsMessageParser.ParseResult.Incomplete, parseResult);
+                    pipe.Reader.Advance(consumed, examined);
 
-                pipe.Reader.Advance(consumed, examined);
+                    // parse result should be complete only after we parsed the last message part
+                    var expectedResult =
+                        i == messageParts.Length - 1
+                            ? ServerSentEventsMessageParser.ParseResult.Completed
+                            : ServerSentEventsMessageParser.ParseResult.Incomplete;
 
-                // Send the rest of the data and parse the complete message
+                    Assert.Equal(expectedResult, parseResult);
-                await pipe.Writer.WriteAsync(Encoding.UTF8.GetBytes(encodedMessagePart2));
+                }
-                result = await pipe.Reader.ReadAsync();
 
-                parseResult = parser.ParseMessage(result.Buffer, out consumed, out examined, out message);
-                Assert.Equal(ServerSentEventsMessageParser.ParseResult.Completed, parseResult);
                 Assert.Equal(expectedMessageType, message.Type);
                 Assert.Equal(consumed, examined);
 

test/Microsoft.AspNetCore.Sockets.Tests/ServerSentEventsTests.cs

@@ -49,9 +49,9 @@ namespace Microsoft.AspNetCore.Sockets.Tests
         }
 
         [Theory]
-        [InlineData("Hello World", "data: T\r\ndata: Hello World\r\n\r\n")]
+        [InlineData("Hello World", ":\r\ndata: T\r\ndata: Hello World\r\n\r\n")]
-        [InlineData("Hello\nWorld", "data: T\r\ndata: Hello\r\ndata: World\r\n\r\n")]
+        [InlineData("Hello\nWorld", ":\r\ndata: T\r\ndata: Hello\r\ndata: World\r\n\r\n")]
-        [InlineData("Hello\r\nWorld", "data: T\r\ndata: Hello\r\ndata: World\r\n\r\n")]
+        [InlineData("Hello\r\nWorld", ":\r\ndata: T\r\ndata: Hello\r\ndata: World\r\n\r\n")]
         public async Task SSEAddsAppropriateFraming(string message, string expected)
         {
             var channel = Channel.CreateUnbounded<Message>();