From a26016fc08780e8d8f75af8a8f718b9c1ddb7bf1 Mon Sep 17 00:00:00 2001
From: Leonardo Galli <leonardo.galli@bluewin.ch>
Date: Sun, 24 Feb 2019 17:58:19 +0100
Subject: [PATCH] Fixed: Mono bug causing memory leakage when http connections
 use gzip compression.

The bug is registered upstream, but this commit works around the problem by doing the gzip decompression separately from the http stack.

Ref #2296
---
 .../Extensions/Pipelines/GZipPipeline.cs      | 34 ++++++++++++++-----
 .../Http/Dispatchers/ManagedHttpDispatcher.cs | 34 ++++++++++++++++---
 2 files changed, 55 insertions(+), 13 deletions(-)

diff --git a/src/NzbDrone.Api/Extensions/Pipelines/GZipPipeline.cs b/src/NzbDrone.Api/Extensions/Pipelines/GZipPipeline.cs
index 8aa9f4ad2..2366b80ac 100644
--- a/src/NzbDrone.Api/Extensions/Pipelines/GZipPipeline.cs
+++ b/src/NzbDrone.Api/Extensions/Pipelines/GZipPipeline.cs
@@ -5,6 +5,7 @@
 using Nancy;
 using Nancy.Bootstrapper;
 using NLog;
+using NzbDrone.Common.EnvironmentInfo;
 using NzbDrone.Common.Extensions;
 
 namespace NzbDrone.Api.Extensions.Pipelines
@@ -15,9 +16,14 @@ public class GzipCompressionPipeline : IRegisterNancyPipeline
 
         public int Order => 0;
 
+        private readonly Action<Action<Stream>, Stream> _writeGZipStream;
+
         public GzipCompressionPipeline(Logger logger)
         {
             _logger = logger;
+
+            // On Mono GZipStream/DeflateStream leaks memory if an exception is thrown, use an intermediate buffer in that case.
+            _writeGZipStream = PlatformInfo.IsMono ? WriteGZipStreamMono : (Action<Action<Stream>, Stream>)WriteGZipStream;
         }
 
         public void Register(IPipelines pipelines)
@@ -43,14 +49,7 @@ private void CompressResponse(NancyContext context)
                     var contents = response.Contents;
 
                     response.Headers["Content-Encoding"] = "gzip";
-                    response.Contents = responseStream =>
-                    {
-                        using (var gzip = new GZipStream(responseStream, CompressionMode.Compress, true))
-                        using (var buffered = new BufferedStream(gzip, 8192))
-                        {
-                            contents.Invoke(buffered);
-                        }
-                    };
+                    response.Contents = responseStream => _writeGZipStream(contents, responseStream);
                 }
             }
 
@@ -61,6 +60,25 @@ private void CompressResponse(NancyContext context)
             }
         }
 
+        private static void WriteGZipStreamMono(Action<Stream> innerContent, Stream targetStream)
+        {
+            using (var membuffer = new MemoryStream())
+            {
+                WriteGZipStream(innerContent, membuffer);
+                membuffer.Position = 0;
+                membuffer.CopyTo(targetStream);
+            }
+        }
+
+        private static void WriteGZipStream(Action<Stream> innerContent, Stream targetStream)
+        {
+            using (var gzip = new GZipStream(targetStream, CompressionMode.Compress, true))
+            using (var buffered = new BufferedStream(gzip, 8192))
+            {
+                innerContent.Invoke(buffered);
+            }
+        }
+
         private static bool ContentLengthIsTooSmall(Response response)
         {
             var contentLength = response.Headers.GetValueOrDefault("Content-Length");
diff --git a/src/NzbDrone.Common/Http/Dispatchers/ManagedHttpDispatcher.cs b/src/NzbDrone.Common/Http/Dispatchers/ManagedHttpDispatcher.cs
index 01b345f9a..d3ae7bbdb 100644
--- a/src/NzbDrone.Common/Http/Dispatchers/ManagedHttpDispatcher.cs
+++ b/src/NzbDrone.Common/Http/Dispatchers/ManagedHttpDispatcher.cs
@@ -1,4 +1,6 @@
 using System;
+using System.IO;
+using System.IO.Compression;
 using System.Net;
 using NzbDrone.Common.EnvironmentInfo;
 using NzbDrone.Common.Extensions;
@@ -26,11 +28,20 @@ public HttpResponse GetResponse(HttpRequest request, CookieContainer cookies)
             {
                 webRequest = (HttpWebRequest) WebRequest.Create((Uri) request.Url);
 
-                // Deflate is not a standard and could break depending on implementation.
-                // we should just stick with the more compatible Gzip
-                //http://stackoverflow.com/questions/8490718/how-to-decompress-stream-deflated-with-java-util-zip-deflater-in-net
-                webRequest.AutomaticDecompression = DecompressionMethods.GZip;
-
+                if (PlatformInfo.IsMono)
+                {
+                    // On Mono GZipStream/DeflateStream leaks memory if an exception is thrown, use an intermediate buffer in that case.
+                    webRequest.AutomaticDecompression = DecompressionMethods.None;
+                    webRequest.Headers.Add("Accept-Encoding", "gzip");
+                }
+                else
+                {
+                    // Deflate is not a standard and could break depending on implementation.
+                    // we should just stick with the more compatible Gzip
+                    //http://stackoverflow.com/questions/8490718/how-to-decompress-stream-deflated-with-java-util-zip-deflater-in-net
+                    webRequest.AutomaticDecompression = DecompressionMethods.GZip;
+                }
+                
                 webRequest.Method = request.Method.ToString();
                 webRequest.UserAgent = request.UseSimplifiedUserAgent
                     ? UserAgentBuilder.UserAgentSimplified
@@ -86,6 +97,19 @@ public HttpResponse GetResponse(HttpRequest request, CookieContainer cookies)
                     if (responseStream != null)
                     {
                         data = responseStream.ToBytes();
+
+                        if (PlatformInfo.IsMono && httpWebResponse.ContentEncoding == "gzip")
+                        {
+                            using (var compressedStream = new MemoryStream(data))
+                            using (var gzip = new GZipStream(compressedStream, CompressionMode.Decompress))
+                            using (var decompressedStream = new MemoryStream())
+                            {
+                                gzip.CopyTo(decompressedStream);
+                                data = decompressedStream.ToArray();
+                            }
+
+                            httpWebResponse.Headers.Remove("Content-Encoding");
+                        }
                     }
                 }