IIS: Identify if a request has a body (#25381)

Author: Tratcher

src/Servers/IIS/IIS/src/Core/IISHttpContext.FeatureCollection.cs

@@ -24,6 +24,7 @@ namespace Microsoft.AspNetCore.Server.IIS.Core
 {
     internal partial class IISHttpContext : IFeatureCollection,
                                             IHttpRequestFeature,
+                                            IHttpRequestBodyDetectionFeature,
                                             IHttpResponseFeature,
                                             IHttpResponseBodyFeature,
                                             IHttpUpgradeFeature,
@@ -141,6 +142,8 @@ Stream IHttpRequestFeature.Body
             set => RequestBody = value;
         }
 
+        bool IHttpRequestBodyDetectionFeature.CanHaveBody => RequestCanHaveBody;
+
         int IHttpResponseFeature.StatusCode
         {
             get => StatusCode;

src/Servers/IIS/IIS/src/Core/IISHttpContext.Features.cs

@@ -9,6 +9,7 @@ namespace Microsoft.AspNetCore.Server.IIS.Core
     internal partial class IISHttpContext
     {
         private static readonly Type IHttpRequestFeatureType = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpRequestFeature);
+        private static readonly Type IHttpRequestBodyDetectionFeature = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpRequestBodyDetectionFeature);
         private static readonly Type IHttpResponseFeatureType = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpResponseFeature);
         private static readonly Type IHttpResponseBodyFeatureType = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpResponseBodyFeature);
         private static readonly Type IHttpRequestIdentifierFeatureType = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpRequestIdentifierFeature);
@@ -32,6 +33,7 @@ internal partial class IISHttpContext
         private static readonly Type IHttpResetFeature = typeof(global::Microsoft.AspNetCore.Http.Features.IHttpResetFeature);
 
         private object _currentIHttpRequestFeature;
+        private object _currentIHttpRequestBodyDetectionFeature;
         private object _currentIHttpResponseFeature;
         private object _currentIHttpResponseBodyFeature;
         private object _currentIHttpRequestIdentifierFeature;
@@ -56,6 +58,7 @@ internal partial class IISHttpContext
         private void Initialize()
         {
             _currentIHttpRequestFeature = this;
+            _currentIHttpRequestBodyDetectionFeature = this;
             _currentIHttpResponseFeature = this;
             _currentIHttpResponseBodyFeature = this;
             _currentIHttpUpgradeFeature = this;
@@ -77,6 +80,10 @@ internal object FastFeatureGet(Type key)
             {
                 return _currentIHttpRequestFeature;
             }
+            if (key == IHttpRequestBodyDetectionFeature)
+            {
+                return _currentIHttpRequestBodyDetectionFeature;
+            }
             if (key == IHttpResponseFeatureType)
             {
                 return _currentIHttpResponseFeature;
@@ -174,6 +181,11 @@ internal void FastFeatureSet(Type key, object feature)
                 _currentIHttpRequestFeature = feature;
                 return;
             }
+            if (key == IHttpRequestBodyDetectionFeature)
+            {
+                _currentIHttpRequestBodyDetectionFeature = feature;
+                return;
+            }
             if (key == IHttpResponseFeatureType)
             {
                 _currentIHttpResponseFeature = feature;
@@ -284,6 +296,10 @@ private IEnumerable<KeyValuePair<Type, object>> FastEnumerable()
             {
                 yield return new KeyValuePair<Type, object>(IHttpRequestFeatureType, _currentIHttpRequestFeature as global::Microsoft.AspNetCore.Http.Features.IHttpRequestFeature);
             }
+            if (_currentIHttpRequestBodyDetectionFeature != null)
+            {
+                yield return new KeyValuePair<Type, object>(IHttpRequestBodyDetectionFeature, _currentIHttpRequestBodyDetectionFeature as global::Microsoft.AspNetCore.Http.Features.IHttpRequestBodyDetectionFeature);
+            }
             if (_currentIHttpResponseFeature != null)
             {
                 yield return new KeyValuePair<Type, object>(IHttpResponseFeatureType, _currentIHttpResponseFeature as global::Microsoft.AspNetCore.Http.Features.IHttpResponseFeature);

src/Servers/IIS/IIS/src/Core/IISHttpContext.cs

@@ -108,6 +108,7 @@ internal unsafe IISHttpContext(
         public string TraceIdentifier { get; set; }
         public ClaimsPrincipal User { get; set; }
         internal WindowsPrincipal WindowsUser { get; set; }
+        internal bool RequestCanHaveBody { get; private set; }
         public Stream RequestBody { get; set; }
         public Stream ResponseBody { get; set; }
         public PipeWriter ResponsePipeWrapper { get; set; }
@@ -165,6 +166,8 @@ protected void InitializeContext()
                 RequestHeaders = new RequestHeaders(this);
                 HttpResponseHeaders = new HeaderCollection();
                 ResponseHeaders = HttpResponseHeaders;
+                // Request headers can be modified by the app, read these first.
+                RequestCanHaveBody = CheckRequestCanHaveBody();
 
                 if (_options.ForwardWindowsAuthentication)
                 {
@@ -250,6 +253,20 @@ public string ReasonPhrase
 
         internal IISHttpServer Server => _server;
 
+        private bool CheckRequestCanHaveBody()
+        {
+            // Http/1.x requests with bodies require either a Content-Length or Transfer-Encoding header.
+            // Note Http.Sys adds the Transfer-Encoding: chunked header to HTTP/2 requests with bodies for back compat.
+            // Transfer-Encoding takes priority over Content-Length.
+            string transferEncoding = RequestHeaders[HttpKnownHeaderNames.TransferEncoding];
+            if (string.Equals("chunked", transferEncoding?.Trim(), StringComparison.OrdinalIgnoreCase))
+            {
+                return true;
+            }
+
+            return RequestHeaders.ContentLength.GetValueOrDefault() > 0;
+        }
+
         private async Task InitializeResponse(bool flushHeaders)
         {
             await FireOnStarting();