From d0ddb068bea92f75fa0c783e97065ecbe3b2e04c Mon Sep 17 00:00:00 2001
From: Pranav K <prkrishn@hotmail.com>
Date: Thu, 13 Sep 2018 13:35:31 -0700
Subject: [PATCH] Return FormCollection.Empty when Content-Length is 0 (#1038)

* Return FormCollection.Empty when Content-Length is 0

Fixes https://github.com/aspnet/Mvc/issues/5631
---
 .../Features/FormFeature.cs                     |  5 +++++
 .../Features/FormFeatureTests.cs                | 17 +++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/Microsoft.AspNetCore.Http/Features/FormFeature.cs b/src/Microsoft.AspNetCore.Http/Features/FormFeature.cs
index 02c1bd7a..865e183f 100644
--- a/src/Microsoft.AspNetCore.Http/Features/FormFeature.cs
+++ b/src/Microsoft.AspNetCore.Http/Features/FormFeature.cs
@@ -131,6 +131,11 @@ private async Task<IFormCollection> InnerReadFormAsync(CancellationToken cancell
 
             cancellationToken.ThrowIfCancellationRequested();
 
+            if (_request.ContentLength == 0)
+            {
+                return FormCollection.Empty;
+            }
+
             if (_options.BufferBody)
             {
                 _request.EnableRewind(_options.MemoryBufferThreshold, _options.BufferBodyLengthLimit);
diff --git a/test/Microsoft.AspNetCore.Http.Tests/Features/FormFeatureTests.cs b/test/Microsoft.AspNetCore.Http.Tests/Features/FormFeatureTests.cs
index 591f46a4..cfa8b021 100644
--- a/test/Microsoft.AspNetCore.Http.Tests/Features/FormFeatureTests.cs
+++ b/test/Microsoft.AspNetCore.Http.Tests/Features/FormFeatureTests.cs
@@ -12,6 +12,23 @@ namespace Microsoft.AspNetCore.Http.Features
 {
     public class FormFeatureTests
     {
+        [Fact]
+        public async Task ReadFormAsync_0ContentLength_ReturnsEmptyForm()
+        {
+            var context = new DefaultHttpContext();
+            var responseFeature = new FakeResponseFeature();
+            context.Features.Set<IHttpResponseFeature>(responseFeature);
+            context.Request.ContentType = MultipartContentType;
+            context.Request.ContentLength = 0;
+
+            var formFeature = new FormFeature(context.Request, new FormOptions());
+            context.Features.Set<IFormFeature>(formFeature);
+
+            var formCollection = await context.Request.ReadFormAsync();
+
+            Assert.Same(FormCollection.Empty, formCollection);
+        }
+
         [Theory]
         [InlineData(true)]
         [InlineData(false)]