Add support for Zlib compression (.NET 6.0 onward only)

README.md

@@ -120,6 +120,14 @@ Private keys can be encrypted using one of the following cipher methods:
 * hmac-sha2-256-etm<span></span>@openssh.com
 * hmac-sha2-512-etm<span></span>@openssh.com
 
+
+## Compression
+
+**SSH.NET** supports the following compression algorithms:
+* none (default)
+* zlib<span></span>@openssh.com (.NET 6 and higher)
+* zlib (.NET 6 and higher)
+
 ## Framework Support
 **SSH.NET** supports the following target frameworks:
 * .NETFramework 4.6.2 (and higher)

src/Renci.SshNet/Compression/ZlibOpenSsh.cs

@@ -3,7 +3,7 @@
 namespace Renci.SshNet.Compression
 {
     /// <summary>
-    /// Represents "zlib@openssh.org" compression implementation.
+    /// Represents "zlib@openssh.com" compression implementation.
     /// </summary>
     public class ZlibOpenSsh : Compressor
     {
@@ -12,7 +12,7 @@ public class ZlibOpenSsh : Compressor
         /// </summary>
         public override string Name
         {
-            get { return "zlib@openssh.org"; }
+            get { return "zlib@openssh.com"; }
         }
 
         /// <summary>

src/Renci.SshNet/Compression/ZlibStream.cs

@@ -1,41 +1,40 @@
 using System.IO;
 
-#pragma warning disable S125 // Sections of code should not be commented out
-#pragma warning disable SA1005 // Single line comments should begin with single space
-
 namespace Renci.SshNet.Compression
 {
     /// <summary>
     /// Implements Zlib compression algorithm.
     /// </summary>
 #pragma warning disable CA1711 // Identifiers should not have incorrect suffix
+#pragma warning disable CA1001 // Types that own disposable fields should be disposable
     public class ZlibStream
+#pragma warning restore CA1001 // Types that own disposable fields should be disposable
 #pragma warning restore CA1711 // Identifiers should not have incorrect suffix
     {
-        //private readonly Ionic.Zlib.ZlibStream _baseStream;
+#if NET6_0_OR_GREATER
+        private readonly System.IO.Compression.ZLibStream _baseStream;
+#endif
 
         /// <summary>
         /// Initializes a new instance of the <see cref="ZlibStream" /> class.
         /// </summary>
         /// <param name="stream">The stream.</param>
         /// <param name="mode">The mode.</param>
-#pragma warning disable IDE0060 // Remove unused parameter
         public ZlibStream(Stream stream, CompressionMode mode)
-#pragma warning restore IDE0060 // Remove unused parameter
         {
-            //switch (mode)
-            //{
-            //    case CompressionMode.Compress:
-            //        this._baseStream = new Ionic.Zlib.ZlibStream(stream, Ionic.Zlib.CompressionMode.Compress, Ionic.Zlib.CompressionLevel.Default);
-            //        break;
-            //    case CompressionMode.Decompress:
-            //        this._baseStream = new Ionic.Zlib.ZlibStream(stream, Ionic.Zlib.CompressionMode.Decompress, Ionic.Zlib.CompressionLevel.Default);
-            //        break;
-            //    default:
-            //        break;
-            //}
-
-            //this._baseStream.FlushMode = Ionic.Zlib.FlushType.Partial;
+#if NET6_0_OR_GREATER
+            switch (mode)
+            {
+                case CompressionMode.Compress:
+                    _baseStream = new System.IO.Compression.ZLibStream(stream, System.IO.Compression.CompressionMode.Compress);
+                    break;
+                case CompressionMode.Decompress:
+                    _baseStream = new System.IO.Compression.ZLibStream(stream, System.IO.Compression.CompressionMode.Decompress);
+                    break;
+                default:
+                    break;
+            }
+#endif
         }
 
         /// <summary>
@@ -44,15 +43,11 @@ public ZlibStream(Stream stream, CompressionMode mode)
         /// <param name="buffer">The buffer.</param>
         /// <param name="offset">The offset.</param>
         /// <param name="count">The count.</param>
-#pragma warning disable IDE0060 // Remove unused parameter
         public void Write(byte[] buffer, int offset, int count)
-#pragma warning restore IDE0060 // Remove unused parameter
         {
-            //this._baseStream.Write(buffer, offset, count);
+#if NET6_0_OR_GREATER
+            _baseStream.Write(buffer, offset, count);
+#endif
         }
-#pragma warning restore SA1005 // Single line comments should begin with single space
     }
 }
-
-#pragma warning restore SA1005 // Single line comments should begin with single space
-#pragma warning restore S125 // Sections of code should not be commented out

src/Renci.SshNet/ConnectionInfo.cs

@@ -439,6 +439,10 @@ public ConnectionInfo(string host, int port, string username, ProxyTypes proxyTy
             CompressionAlgorithms = new Dictionary<string, Func<Compressor>>
                 {
                     { "none", null },
+#if NET6_0_OR_GREATER
+                    { "[email protected]", () => new ZlibOpenSsh() },
+                    { "zlib", () => new Zlib() },
+#endif
                 };
 
             ChannelRequests = new Dictionary<string, RequestInfo>

src/Renci.SshNet/Security/KeyExchange.cs

@@ -124,7 +124,7 @@ from a in message.MacAlgorithmsServerToClient
             var compressionAlgorithmName = (from b in session.ConnectionInfo.CompressionAlgorithms.Keys
                                             from a in message.CompressionAlgorithmsClientToServer
                                             where a == b
-                                            select a).LastOrDefault();
+                                            select a).FirstOrDefault();
             if (string.IsNullOrEmpty(compressionAlgorithmName))
             {
                 throw new SshConnectionException("Compression algorithm not found", DisconnectReason.KeyExchangeFailed);
@@ -136,7 +136,7 @@ from a in message.CompressionAlgorithmsClientToServer
             var decompressionAlgorithmName = (from b in session.ConnectionInfo.CompressionAlgorithms.Keys
                                               from a in message.CompressionAlgorithmsServerToClient
                                               where a == b
-                                              select a).LastOrDefault();
+                                              select a).FirstOrDefault();
             if (string.IsNullOrEmpty(decompressionAlgorithmName))
             {
                 throw new SshConnectionException("Decompression algorithm not found", DisconnectReason.KeyExchangeFailed);

test/Renci.SshNet.IntegrationTests/CompressionTests.cs

@@ -0,0 +1,42 @@
+using Renci.SshNet.Compression;
+
+namespace Renci.SshNet.IntegrationTests
+{
+    [TestClass]
+    public class CompressionTests : IntegrationTestBase
+    {
+        private IConnectionInfoFactory _connectionInfoFactory;
+
+        [TestInitialize]
+        public void SetUp()
+        {
+            _connectionInfoFactory = new LinuxVMConnectionFactory(SshServerHostName, SshServerPort);
+        }
+
+        [TestMethod]
+        public void None()
+        {
+            DoTest(new KeyValuePair<string, Func<Compressor>>("none", null));
+        }
+
+#if NET6_0_OR_GREATER
+        [TestMethod]
+        public void ZlibOpenSsh()
+        {
+            DoTest(new KeyValuePair<string, Func<Compressor>>("[email protected]", () => new ZlibOpenSsh()));
+        }
+#endif
+
+        private void DoTest(KeyValuePair<string, Func<Compressor>> compressor)
+        {
+            using (var client = new SshClient(_connectionInfoFactory.Create()))
+            {
+                client.ConnectionInfo.CompressionAlgorithms.Clear();
+                client.ConnectionInfo.CompressionAlgorithms.Add(compressor);
+
+                client.Connect();
+                client.Disconnect();
+            }
+        }
+    }
+}