Changing the way in which Accept is validated. Resolves #34

Author: tpeczek

Lib.AspNetCore.ServerSentEvents/Lib.AspNetCore.ServerSentEvents.csproj

@@ -3,7 +3,7 @@
     <Description>Lib.AspNetCore.ServerSentEvents is a library which provides Server-Sent Events (SSE) support for ASP.NET Core</Description>
     <Copyright>Copyright © 2017 - 2020 Tomasz Pęczek</Copyright>
     <VersionPrefix>5.0.0</VersionPrefix>
-    <VersionSuffix>alpha2</VersionSuffix>
+    <VersionSuffix>alpha3</VersionSuffix>
     <Authors>Tomasz Pęczek</Authors>
     <TargetFrameworks>netcoreapp2.1;netcoreapp3.0;net461</TargetFrameworks>
     <AssemblyTitle>Lib.AspNetCore.ServerSentEvents</AssemblyTitle>

Lib.AspNetCore.ServerSentEvents/ServerSentEventsMiddleware.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
@@ -52,7 +53,7 @@ public ServerSentEventsMiddleware(RequestDelegate next, IAuthorizationPolicyProv
         /// <returns>The task object representing the asynchronous operation.</returns>
         public async Task Invoke(HttpContext context, IPolicyEvaluator policyEvaluator)
         {
-            if (context.Request.Headers[Constants.ACCEPT_HTTP_HEADER] == Constants.SSE_CONTENT_TYPE)
+            if (CheckAcceptHeader(context.Request.Headers))
             {
                 if (!await AuthorizeAsync(context, policyEvaluator))
                 {
@@ -84,6 +85,26 @@ public async Task Invoke(HttpContext context, IPolicyEvaluator policyEvaluator)
             }
         }
 
+        private bool CheckAcceptHeader(IHeaderDictionary requestHeaders)
+        {
+            if (!requestHeaders.ContainsKey(Constants.ACCEPT_HTTP_HEADER))
+            {
+                return true;
+            }
+
+            if (requestHeaders[Constants.ACCEPT_HTTP_HEADER].Count == 0)
+            {
+                return true;
+            }
+
+            if (requestHeaders[Constants.ACCEPT_HTTP_HEADER].Any(acceptHeaderValue => acceptHeaderValue == Constants.SSE_CONTENT_TYPE))
+            {
+                return true;
+            }
+
+            return false;
+        }
+
         private async Task<bool> AuthorizeAsync(HttpContext context, IPolicyEvaluator policyEvaluator)
         {
             bool authorized = false;

Test.AspNetCore.ServerSentEvents/Middleware/HandshakeTests.cs

@@ -34,11 +34,15 @@ private ServerSentEventsMiddleware<ServerSentEventsService> PrepareServerSentEve
             );
         }
 
-        private HttpContext PrepareHttpContext()
+        private HttpContext PrepareHttpContext(string acceptHeaderValue)
         {
             HttpContext context = new DefaultHttpContext();
 
-            context.Request.Headers.Append(ACCEPT_HTTP_HEADER, SSE_CONTENT_TYPE);
+            if (acceptHeaderValue != null)
+            {
+                context.Request.Headers.Append(ACCEPT_HTTP_HEADER, acceptHeaderValue);
+            }
+
             context.RequestAborted = new CancellationToken(true);
 
             return context;
@@ -47,16 +51,38 @@ private HttpContext PrepareHttpContext()
 
         #region Tests
         [Fact]
-        public async Task Invoke_SseRequest_Accepts()
+        public async Task Invoke_SseRequestWithoutAcceptHeader_Accepts()
         {
             ServerSentEventsMiddleware<ServerSentEventsService> serverSentEventsMiddleware = PrepareServerSentEventsMiddleware();
-            HttpContext context = PrepareHttpContext();
+            HttpContext context = PrepareHttpContext(null);
 
             await serverSentEventsMiddleware.Invoke(context, null);
 
             Assert.Equal(SSE_CONTENT_TYPE, context.Response.ContentType);
         }
 
+        [Fact]
+        public async Task Invoke_SseRequestWithEventStreamAcceptHeader_Accepts()
+        {
+            ServerSentEventsMiddleware<ServerSentEventsService> serverSentEventsMiddleware = PrepareServerSentEventsMiddleware();
+            HttpContext context = PrepareHttpContext(SSE_CONTENT_TYPE);
+
+            await serverSentEventsMiddleware.Invoke(context, null);
+
+            Assert.Equal(SSE_CONTENT_TYPE, context.Response.ContentType);
+        }
+
+        [Fact]
+        public async Task Invoke_SseRequestWithNotEventStreamAcceptHeader_Accepts()
+        {
+            ServerSentEventsMiddleware<ServerSentEventsService> serverSentEventsMiddleware = PrepareServerSentEventsMiddleware();
+            HttpContext context = PrepareHttpContext("text/plain");
+
+            await serverSentEventsMiddleware.Invoke(context, null);
+
+            Assert.Null(context.Response.ContentType);
+        }
+
         [Fact]
         public async Task Invoke_SseRequest_CallsOnPrepareAccept()
         {
@@ -66,7 +92,7 @@ public async Task Invoke_SseRequest_CallsOnPrepareAccept()
                 OnPrepareAccept = onPrepareAcceptMock.Object
             });
 
-            await serverSentEventsMiddleware.Invoke(PrepareHttpContext(), null);
+            await serverSentEventsMiddleware.Invoke(PrepareHttpContext(null), null);
 
             onPrepareAcceptMock.Verify(m => m(It.IsAny<HttpResponse>()), Times.Once);
         }