Add Brotli support to SocketsHttpHandler (dotnet/corefx#29729)

* Add Brotli support to SocketsHttpHandler

- Add DecompressionMethods.Brotli
- Add support for Brotli to SocketsHttpHandler
- Add some tests

* Address PR feedback


Commit migrated from dotnet/corefx@91f2cd7

src/libraries/System.Net.Http/src/System.Net.Http.csproj

@@ -602,6 +602,7 @@
     <Reference Include="System.Diagnostics.Tools" />
     <Reference Include="System.Diagnostics.Tracing" />
     <Reference Include="System.IO.Compression" />
+    <Reference Include="System.IO.Compression.Brotli" />
     <Reference Include="System.Memory" />
     <Reference Include="System.Net.NetworkInformation" />
     <Reference Include="System.Net.Primitives" />

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/DecompressionHandler.cs

@@ -19,8 +19,10 @@ internal sealed class DecompressionHandler : HttpMessageHandler
 
         private const string s_gzip = "gzip";
         private const string s_deflate = "deflate";
+        private const string s_brotli = "br";
         private static readonly StringWithQualityHeaderValue s_gzipHeaderValue = new StringWithQualityHeaderValue(s_gzip);
         private static readonly StringWithQualityHeaderValue s_deflateHeaderValue = new StringWithQualityHeaderValue(s_deflate);
+        private static readonly StringWithQualityHeaderValue s_brotliHeaderValue = new StringWithQualityHeaderValue(s_brotli);
 
         public DecompressionHandler(DecompressionMethods decompressionMethods, HttpMessageHandler innerHandler)
         {
@@ -33,6 +35,7 @@ public DecompressionHandler(DecompressionMethods decompressionMethods, HttpMessa
 
         internal bool GZipEnabled => (_decompressionMethods & DecompressionMethods.GZip) != 0;
         internal bool DeflateEnabled => (_decompressionMethods & DecompressionMethods.Deflate) != 0;
+        internal bool BrotliEnabled => (_decompressionMethods & DecompressionMethods.Brotli) != 0;
 
         protected internal override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
         {
@@ -44,6 +47,10 @@ protected internal override async Task<HttpResponseMessage> SendAsync(HttpReques
             {
                 request.Headers.AcceptEncoding.Add(s_deflateHeaderValue);
             }
+            if (BrotliEnabled)
+            {
+                request.Headers.AcceptEncoding.Add(s_brotliHeaderValue);
+            }
 
             HttpResponseMessage response = await _innerHandler.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
@@ -64,6 +71,10 @@ protected internal override async Task<HttpResponseMessage> SendAsync(HttpReques
                 {
                     response.Content = new DeflateDecompressedContent(response.Content);
                 }
+                else if (BrotliEnabled && last == s_brotli)
+                {
+                    response.Content = new BrotliDecompressedContent(response.Content);
+                }
             }
 
             return response;
@@ -167,5 +178,16 @@ public DeflateDecompressedContent(HttpContent originalContent)
             protected override Stream GetDecompressedStream(Stream originalStream) =>
                 new DeflateStream(originalStream, CompressionMode.Decompress);
         }
+
+        private sealed class BrotliDecompressedContent : DecompressedContent
+        {
+            public BrotliDecompressedContent(HttpContent originalContent) :
+                base(originalContent)
+            {
+            }
+
+            protected override Stream GetDecompressedStream(Stream originalStream) =>
+                new BrotliStream(originalStream, CompressionMode.Decompress);
+        }
     }
 }

src/libraries/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.Decompression.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Collections.Generic;
 using System.IO;
 using System.IO.Compression;
 using System.Net.Test.Common;
@@ -12,34 +13,115 @@ namespace System.Net.Http.Functional.Tests
 {
     public abstract class HttpClientHandler_Decompression_Test : HttpClientTestBase
     {
-        [Fact]
-        public async Task Brotli_DecompressesResponse_Success()
+        public static IEnumerable<object[]> DecompressedResponse_MethodSpecified_DecompressedContentReturned_MemberData()
+        {
+            foreach (bool specifyAllMethods in new[] { false, true })
+            {
+                yield return new object[]
+                {
+                    "deflate",
+                    new Func<Stream, Stream>(s => new DeflateStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                    specifyAllMethods ? DecompressionMethods.Deflate : ~DecompressionMethods.None
+                };
+                yield return new object[]
+                {
+                    "gzip",
+                    new Func<Stream, Stream>(s => new GZipStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                    specifyAllMethods ? DecompressionMethods.GZip : ~DecompressionMethods.None
+                };
+                yield return new object[]
+                {
+                    "br",
+                    new Func<Stream, Stream>(s => new BrotliStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                    specifyAllMethods ? DecompressionMethods.Brotli : ~DecompressionMethods.None
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(DecompressedResponse_MethodSpecified_DecompressedContentReturned_MemberData))]
+        public async Task DecompressedResponse_MethodSpecified_DecompressedContentReturned(
+            string encodingName, Func<Stream, Stream> compress, DecompressionMethods methods)
         {
             var expectedContent = new byte[12345];
             new Random(42).NextBytes(expectedContent);
 
             await LoopbackServer.CreateClientAndServerAsync(async uri =>
             {
-                using (HttpClient client = CreateHttpClient())
-                using (HttpResponseMessage response = await client.GetAsync(uri, HttpCompletionOption.ResponseHeadersRead))
-                using (var decodedStream = new BrotliStream(await response.Content.ReadAsStreamAsync(), CompressionMode.Decompress))
+                using (HttpClientHandler handler = CreateHttpClientHandler())
+                using (var client = new HttpClient(handler))
                 {
-                    var data = new MemoryStream();
-                    await decodedStream.CopyToAsync(data);
-                    Assert.Equal(expectedContent, data.ToArray());
+                    handler.AutomaticDecompression = methods;
+                    Assert.Equal<byte>(expectedContent, await client.GetByteArrayAsync(uri));
                 }
             }, async server =>
             {
                 await server.AcceptConnectionAsync(async connection =>
                 {
                     await connection.ReadRequestHeaderAsync();
-                    await connection.Writer.WriteAsync("HTTP/1.1 200 OK\r\nContent-Encoding: br\r\n\r\n");
-                    using (var brotli = new BrotliStream(connection.Stream, CompressionLevel.Optimal, leaveOpen: true))
+                    await connection.Writer.WriteAsync($"HTTP/1.1 200 OK\r\nContent-Encoding: {encodingName}\r\n\r\n");
+                    using (Stream compressedStream = compress(connection.Stream))
                     {
-                        await brotli.WriteAsync(expectedContent);
+                        await compressedStream.WriteAsync(expectedContent);
                     }
                 });
             });
         }
+
+        public static IEnumerable<object[]> DecompressedResponse_MethodNotSpecified_OriginalContentReturned_MemberData()
+        {
+            yield return new object[]
+            {
+                "deflate",
+                new Func<Stream, Stream>(s => new DeflateStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                DecompressionMethods.None
+            };
+            yield return new object[]
+            {
+                "gzip",
+                new Func<Stream, Stream>(s => new GZipStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                DecompressionMethods.Brotli
+            };
+            yield return new object[]
+            {
+                "br",
+                new Func<Stream, Stream>(s => new BrotliStream(s, CompressionLevel.Optimal, leaveOpen: true)),
+                DecompressionMethods.Deflate | DecompressionMethods.GZip
+            };
+        }
+
+        [Theory]
+        [MemberData(nameof(DecompressedResponse_MethodNotSpecified_OriginalContentReturned_MemberData))]
+        public async Task DecompressedResponse_MethodNotSpecified_OriginalContentReturned(
+            string encodingName, Func<Stream, Stream> compress, DecompressionMethods methods)
+        {
+            var expectedContent = new byte[12345];
+            new Random(42).NextBytes(expectedContent);
+
+            var compressedContentStream = new MemoryStream();
+            using (Stream s = compress(compressedContentStream))
+            {
+                await s.WriteAsync(expectedContent);
+            }
+            byte[] compressedContent = compressedContentStream.ToArray();
+
+            await LoopbackServer.CreateClientAndServerAsync(async uri =>
+            {
+                using (HttpClientHandler handler = CreateHttpClientHandler())
+                using (var client = new HttpClient(handler))
+                {
+                    handler.AutomaticDecompression = methods;
+                    Assert.Equal<byte>(compressedContent, await client.GetByteArrayAsync(uri));
+                }
+            }, async server =>
+            {
+                await server.AcceptConnectionAsync(async connection =>
+                {
+                    await connection.ReadRequestHeaderAsync();
+                    await connection.Writer.WriteAsync($"HTTP/1.1 200 OK\r\nContent-Encoding: {encodingName}\r\n\r\n");
+                    await connection.Stream.WriteAsync(compressedContent);
+                });
+            });
+        }
     }
 }

src/libraries/System.Net.Primitives/ref/System.Net.Primitives.cs

@@ -101,6 +101,7 @@ public void Remove(System.Uri uriPrefix, string authType) { }
     [System.FlagsAttribute]
     public enum DecompressionMethods
     {
+        Brotli = 4,
         Deflate = 2,
         GZip = 1,
         None = 0,

src/libraries/System.Net.Primitives/src/System/Net/DecompressionMethods.cs

@@ -8,7 +8,8 @@ namespace System.Net
     public enum DecompressionMethods
     {
         None = 0,
-        GZip = 1,
-        Deflate = 2
+        GZip = 0x1,
+        Deflate = 0x2,
+        Brotli = 0x4
     }
 }