Improve the error message for SPDY

dotnet · Jan 28, 2025 · 93d0a04 · 93d0a04
1 parent 33bff40
commit 93d0a04
Showing 1 changed file with 7 additions and 4 deletions.
diff --git a/src/ReverseProxy/Forwarder/HttpForwarder.cs b/src/ReverseProxy/Forwarder/HttpForwarder.cs
@@ -370,9 +370,10 @@ public async ValueTask<ForwarderError> SendAsync(
         var outgoingUpgrade = false;
         var outgoingConnect = false;
         var tryDowngradingH2WsOnFailure = false;
+
         if (isSpdyRequest)
         {
-            // Can only be done on HTTP/1.1, force regardless of options.
+            // Can only be done on HTTP/1.1.
             outgoingUpgrade = true;
         }
         else if (isH1WsRequest || isH2WsRequest)
@@ -384,6 +385,7 @@ public async ValueTask<ForwarderError> SendAsync(
                 case (2, HttpVersionPolicy.RequestVersionOrHigher, _):
                     outgoingConnect = true;
                     break;
+
                 case (1, HttpVersionPolicy.RequestVersionOrHigher, true):
                 case (2, HttpVersionPolicy.RequestVersionOrLower, true):
                 case (3, HttpVersionPolicy.RequestVersionOrLower, true):
@@ -392,8 +394,7 @@ public async ValueTask<ForwarderError> SendAsync(
                     tryDowngradingH2WsOnFailure = true;
                     break;
 #endif
-                // 1.x Lower or Exact, regardless of HTTPS
-                // Anything else without HTTPS except 2 Exact
+
                 default:
                     // Override to use HTTP/1.1, nothing else is supported.
                     outgoingUpgrade = true;
@@ -408,7 +409,9 @@ public async ValueTask<ForwarderError> SendAsync(
             // Can only be done on HTTP/1.1, throw if disallowed by options.
             if (!http1IsAllowed)
             {
-                throw new HttpRequestException("An outgoing HTTP/1.1 Upgrade request is required to proxy this request, but is disallowed by HttpVersionPolicy.");
+                throw new HttpRequestException(isSpdyRequest
+                    ? "SPDY requests require HTTP/1.1 support, but outbound HTTP/1.1 was disallowed by HttpVersionPolicy."
+                    : "An outgoing HTTP/1.1 Upgrade request is required to proxy this request, but is disallowed by HttpVersionPolicy.");
             }
 
             destinationRequest.Version = HttpVersion.Version11;