Add test for ensuring HPACK lowercase header names

- ensure lowercase mask only applied to uppercase letters

src/Kestrel.Core/Internal/Http2/HPack/HPackEncoder.cs

@@ -141,7 +141,7 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http2.HPack
                     return false;
                 }
 
-                buffer[i++] = (byte)(s[j] | (lowercase ? toLowerMask : 0));
+                buffer[i++] = (byte)(s[j] | (lowercase && s[j] >= (byte)'A' && s[j] <= (byte)'Z' ? toLowerMask : 0));
             }
 
             length = i;

test/Kestrel.Core.Tests/HPackEncoderTests.cs

@@ -10,37 +10,96 @@ namespace Microsoft.AspNetCore.Server.Kestrel.Core.Tests
 {
     public class HPackEncoderTests
     {
-        [Fact]
+        public static TheoryData<KeyValuePair<string, string>[], byte[], int?> SinglePayloadData
-        public void EncodesHeadersInSinglePayloadWhenSpaceAvailable()
+        {
+            get
+            {
+                var data = new TheoryData<KeyValuePair<string, string>[], byte[], int?>();
+
+                // Lowercase header name letters only
+                data.Add(
+                    new[]
+                    {
+                        new KeyValuePair<string, string>("CustomHeader", "CustomValue"),
+                    },
+                    new byte[]
+                    {
+                        // 0    12     c     u     s     t     o     m
+                        0x00, 0x0c, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d,
+                        // h     e     a     d     e     r    11     C
+                        0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x0b, 0x43,
+                        // u     s     t     o     m     V     a     l
+                        0x75, 0x73, 0x74, 0x6f, 0x6d, 0x56, 0x61, 0x6c,
+                        // u     e
+                        0x75, 0x65
+                    },
+                    null);
+                // Lowercase header name letters only
+                data.Add(
+                    new[]
+                    {
+                        new KeyValuePair<string, string>("CustomHeader!#$%&'*+-.^_`|~", "CustomValue"),
+                    },
+                    new byte[]
+                    {
+                        // 0    27     c     u     s     t     o     m
+                        0x00, 0x1b, 0x63, 0x75, 0x73, 0x74, 0x6f, 0x6d,
+                        // h     e     a     d     e     r     !     #
+                        0x68, 0x65, 0x61, 0x64, 0x65, 0x72, 0x21, 0x23,
+                        // $     %     &     '     *     +     -     .
+                        0x24, 0x25, 0x26, 0x27, 0x2a, 0x2b, 0x2d, 0x2e,
+                        // ^     _     `     |     ~    11     C     u
+                        0x5e, 0x5f, 0x60, 0x7c, 0x7e, 0x0b, 0x43, 0x75,
+                        // s     t     o     m     V     a     l     u
+                        0x73, 0x74, 0x6f, 0x6d, 0x56, 0x61, 0x6c, 0x75,
+                        // e
+                        0x65
+                    },
+                    null);
+                // Single Payload
+                data.Add(
+                    new[]
+                    {
+                        new KeyValuePair<string, string>("date", "Mon, 24 Jul 2017 19:22:30 GMT"),
+                        new KeyValuePair<string, string>("content-type", "text/html; charset=utf-8"),
+                        new KeyValuePair<string, string>("server", "Kestrel")
+                    },
+                    new byte[]
+                    {
+                        0x88, 0x00, 0x04, 0x64, 0x61, 0x74, 0x65, 0x1d,
+                        0x4d, 0x6f, 0x6e, 0x2c, 0x20, 0x32, 0x34, 0x20,
+                        0x4a, 0x75, 0x6c, 0x20, 0x32, 0x30, 0x31, 0x37,
+                        0x20, 0x31, 0x39, 0x3a, 0x32, 0x32, 0x3a, 0x33,
+                        0x30, 0x20, 0x47, 0x4d, 0x54, 0x00, 0x0c, 0x63,
+                        0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x74,
+                        0x79, 0x70, 0x65, 0x18, 0x74, 0x65, 0x78, 0x74,
+                        0x2f, 0x68, 0x74, 0x6d, 0x6c, 0x3b, 0x20, 0x63,
+                        0x68, 0x61, 0x72, 0x73, 0x65, 0x74, 0x3d, 0x75,
+                        0x74, 0x66, 0x2d, 0x38, 0x00, 0x06, 0x73, 0x65,
+                        0x72, 0x76, 0x65, 0x72, 0x07, 0x4b, 0x65, 0x73,
+                        0x74, 0x72, 0x65, 0x6c
+                    },
+                    200);
+
+                return data;
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(SinglePayloadData))]
+        public void EncodesHeadersInSinglePayloadWhenSpaceAvailable(KeyValuePair<string, string>[] headers, byte[] expectedPayload, int? statusCode)
         {
             var encoder = new HPackEncoder();
-
-            var statusCode = 200;
-            var headers = new []
-            {
-                new KeyValuePair<string, string>("date", "Mon, 24 Jul 2017 19:22:30 GMT"),
-                new KeyValuePair<string, string>("content-type", "text/html; charset=utf-8"),
-                new KeyValuePair<string, string>("server", "Kestrel")
-            };
-
-            var expectedPayload = new byte[]
-            {
-                0x88, 0x00, 0x04, 0x64, 0x61, 0x74, 0x65, 0x1d,
-                0x4d, 0x6f, 0x6e, 0x2c, 0x20, 0x32, 0x34, 0x20,
-                0x4a, 0x75, 0x6c, 0x20, 0x32, 0x30, 0x31, 0x37,
-                0x20, 0x31, 0x39, 0x3a, 0x32, 0x32, 0x3a, 0x33,
-                0x30, 0x20, 0x47, 0x4d, 0x54, 0x00, 0x0c, 0x63,
-                0x6f, 0x6e, 0x74, 0x65, 0x6e, 0x74, 0x2d, 0x74,
-                0x79, 0x70, 0x65, 0x18, 0x74, 0x65, 0x78, 0x74,
-                0x2f, 0x68, 0x74, 0x6d, 0x6c, 0x3b, 0x20, 0x63,
-                0x68, 0x61, 0x72, 0x73, 0x65, 0x74, 0x3d, 0x75,
-                0x74, 0x66, 0x2d, 0x38, 0x00, 0x06, 0x73, 0x65,
-                0x72, 0x76, 0x65, 0x72, 0x07, 0x4b, 0x65, 0x73,
-                0x74, 0x72, 0x65, 0x6c
-            };
-
             var payload = new byte[1024];
-            Assert.True(encoder.BeginEncode(statusCode, headers, payload, out var length));
+            var length = 0;
+            if (statusCode.HasValue)
+            {
+                Assert.True(encoder.BeginEncode(statusCode.Value, headers, payload, out length));
+            }
+            else
+            {
+                Assert.True(encoder.BeginEncode(headers, payload, out length));
+            }
             Assert.Equal(expectedPayload.Length, length);
 
             for (var i = 0; i < length; i++)