Merge branch 'feature/handle_empty_forms' into develop

Resolves #33

Author: Jericho

Source/HttpMultipartParser.UnitTests/ParserScenarios/EmptyForm.cs

@@ -0,0 +1,69 @@
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace HttpMultipartParser.UnitTests.ParserScenarios
+{
+    public class EmptyForm
+    {
+        private static readonly string _testData = TestUtil.TrimAllLines(
+           @"------WebKitFormBoundaryb4SfPlH9Bv7c2PKS--"
+        );
+
+        private static readonly TestData _testCase = new TestData(
+            _testData,
+            Enumerable.Empty<ParameterPart>().ToList(),
+            Enumerable.Empty<FilePart>().ToList()
+        );
+
+        public EmptyForm()
+        {
+            foreach (var filePart in _testCase.ExpectedFileData)
+            {
+                filePart.Data.Position = 0;
+            }
+        }
+
+        [Fact]
+        public void Parse_empty_form_boundary_specified()
+        {
+            using (Stream stream = TestUtil.StringToStream(_testCase.Request, Encoding.UTF8))
+            {
+                var parser = MultipartFormDataParser.Parse(stream, "----WebKitFormBoundaryb4SfPlH9Bv7c2PKS");
+                Assert.True(_testCase.Validate(parser));
+            }
+        }
+
+        [Fact]
+        public void Parse_empty_form_boundary_omitted()
+        {
+            using (Stream stream = TestUtil.StringToStream(_testCase.Request, Encoding.UTF8))
+            {
+                var parser = MultipartFormDataParser.Parse(stream);
+                Assert.True(_testCase.Validate(parser));
+            }
+        }
+
+        [Fact]
+        public async Task Parse_empty_form_boundary_specified_async()
+        {
+            using (Stream stream = TestUtil.StringToStream(_testCase.Request, Encoding.UTF8))
+            {
+                var parser = await MultipartFormDataParser.ParseAsync(stream, "----WebKitFormBoundaryb4SfPlH9Bv7c2PKS").ConfigureAwait(false);
+                Assert.True(_testCase.Validate(parser));
+            }
+        }
+
+        [Fact]
+        public async Task Parse_empty_form_boundary_omitted_async()
+        {
+            using (Stream stream = TestUtil.StringToStream(_testCase.Request, Encoding.UTF8))
+            {
+                var parser = await MultipartFormDataParser.ParseAsync(stream).ConfigureAwait(false);
+                Assert.True(_testCase.Validate(parser));
+            }
+        }
+    }
+}

Source/HttpMultipartParser/StreamingMultipartFormDataParser.cs

@@ -351,7 +351,19 @@ private static string DetectBoundary(RebufferableBinaryReader reader)
             // Presumably the boundary is --|||||||||||||| where -- is the stuff added on to
             // the front as per the protocol and ||||||||||||| is the part we care about.
             string boundary = string.Concat(reader.ReadLine().Skip(2));
-            reader.Buffer("--" + boundary + "\n");
+
+            // If the string ends with '--' it means that we found the "end" boundary and we
+            // need to trim the two dashes to get the actual boundary
+            if (boundary.EndsWith("--"))
+            {
+                boundary = boundary.Substring(0, boundary.Length - 2);
+                reader.Buffer($"--{boundary}--\n");
+            }
+            else
+            {
+                reader.Buffer($"--{boundary}\n");
+            }
+
             return boundary;
         }
 
@@ -374,8 +386,20 @@ private static async Task<string> DetectBoundaryAsync(RebufferableBinaryReader r
             // Presumably the boundary is --|||||||||||||| where -- is the stuff added on to
             // the front as per the protocol and ||||||||||||| is the part we care about.
             var line = await reader.ReadLineAsync(cancellationToken).ConfigureAwait(false);
-            var boundary = string.Concat(line.Skip(2));
-            reader.Buffer("--" + boundary + "\n");
+            string boundary = string.Concat(line.Skip(2));
+
+            // If the string ends with '--' it means that we found the "end" boundary and we
+            // need to trim the two dashes to get the actual boundary.
+            if (boundary.EndsWith("--"))
+            {
+                boundary = boundary.Substring(0, boundary.Length - 2);
+                reader.Buffer($"--{boundary}--\n");
+            }
+            else
+            {
+                reader.Buffer($"--{boundary}\n");
+            }
+
             return boundary;
         }
 
@@ -470,12 +494,17 @@ private void Parse(RebufferableBinaryReader reader)
             while (true)
             {
                 string line = reader.ReadLine();
+
                 if (line == boundary)
                 {
                     break;
                 }
-
-                if (line == null)
+                else if (line == endBoundary)
+                {
+                    readEndBoundary = true;
+                    break;
+                }
+                else if (line == null)
                 {
                     throw new MultipartParseException("Could not find expected boundary");
                 }
@@ -518,12 +547,17 @@ private async Task ParseAsync(RebufferableBinaryReader reader, CancellationToken
             while (true)
             {
                 string line = await reader.ReadLineAsync(cancellationToken).ConfigureAwait(false);
+
                 if (line == boundary)
                 {
                     break;
                 }
-
-                if (line == null)
+                else if (line == endBoundary)
+                {
+                    readEndBoundary = true;
+                    break;
+                }
+                else if (line == null)
                 {
                     throw new MultipartParseException("Could not find expected boundary");
                 }