From cdd3d182b5ea3d6e04ccbc5d032e192ee3d70e3e Mon Sep 17 00:00:00 2001
From: TalAloni <tal.aloni.il@gmail.com>
Date: Fri, 13 Nov 2020 15:32:16 +0200
Subject: [PATCH] Added SMB2TransformHeader implementation

---
 .../SMB2/Enums/SMB2TransformHeaderFlags.cs    | 10 ++++
 SMBLibrary/SMB2/SMB2TransformHeader.cs        | 57 +++++++++++++++++++
 SMBLibrary/SMBLibrary.VS2005.csproj           |  2 +
 3 files changed, 69 insertions(+)
 create mode 100644 SMBLibrary/SMB2/Enums/SMB2TransformHeaderFlags.cs
 create mode 100644 SMBLibrary/SMB2/SMB2TransformHeader.cs

diff --git a/SMBLibrary/SMB2/Enums/SMB2TransformHeaderFlags.cs b/SMBLibrary/SMB2/Enums/SMB2TransformHeaderFlags.cs
new file mode 100644
index 0000000..70dbd28
--- /dev/null
+++ b/SMBLibrary/SMB2/Enums/SMB2TransformHeaderFlags.cs
@@ -0,0 +1,10 @@
+using System;
+
+namespace SMBLibrary.SMB2
+{
+    [Flags]
+    public enum SMB2TransformHeaderFlags : ushort
+    {
+        Encrypted = 0x0001,
+    }
+}
diff --git a/SMBLibrary/SMB2/SMB2TransformHeader.cs b/SMBLibrary/SMB2/SMB2TransformHeader.cs
new file mode 100644
index 0000000..7c39dfb
--- /dev/null
+++ b/SMBLibrary/SMB2/SMB2TransformHeader.cs
@@ -0,0 +1,57 @@
+/* Copyright (C) 2020 Tal Aloni <tal.aloni.il@gmail.com>. All rights reserved.
+ * 
+ * You can redistribute this program and/or modify it under the terms of
+ * the GNU Lesser Public License as published by the Free Software Foundation,
+ * either version 3 of the License, or (at your option) any later version.
+ */
+using System;
+using Utilities;
+
+namespace SMBLibrary.SMB2
+{
+    /// <summary>
+    /// Used by the client or server when sending encrypted messages. only valid for the SMB 3.x dialect family.
+    /// </summary>
+    public class SMB2TransformHeader
+    {
+        public const int Length = 52;
+        public const int SignatureOffset = 4;
+
+        public static readonly byte[] ProtocolSignature = new byte[] { 0xFD, 0x53, 0x4D, 0x42 };
+
+        private byte[] ProtocolId; // 4 bytes, 0xFD followed by "SMB"
+        public byte[] Signature; // 16 bytes
+        public byte[] Nonce; // 16 bytes
+        public uint OriginalMessageSize;
+        public ushort Reserved;
+        public SMB2TransformHeaderFlags Flags; // EncryptionAlgorithm in SMB 3.0 / 3.0.2 where the only possible value is SMB2_ENCRYPTION_AES128_CCM = 0x0001 
+        public ulong SessionId;
+
+        public SMB2TransformHeader()
+        {
+            ProtocolId = ProtocolSignature;
+        }
+
+        public SMB2TransformHeader(byte[] buffer, int offset)
+        {
+            ProtocolId = ByteReader.ReadBytes(buffer, offset + 0, 4);
+            Signature = ByteReader.ReadBytes(buffer, offset + 4, 16);
+            Nonce = ByteReader.ReadBytes(buffer, offset + 20, 16);
+            OriginalMessageSize = LittleEndianConverter.ToUInt32(buffer, offset + 36);
+            Reserved = LittleEndianConverter.ToUInt16(buffer, offset + 40);
+            Flags = (SMB2TransformHeaderFlags)LittleEndianConverter.ToUInt16(buffer, offset + 42);
+            SessionId = LittleEndianConverter.ToUInt64(buffer, offset + 44);
+        }
+
+        public void WriteBytes(byte[] buffer, int offset)
+        {
+            ByteWriter.WriteBytes(buffer, offset + 0, ProtocolId);
+            ByteWriter.WriteBytes(buffer, offset + 4, Signature);
+            ByteWriter.WriteBytes(buffer, offset + 20, Nonce);
+            LittleEndianWriter.WriteUInt32(buffer, offset + 36, OriginalMessageSize);
+            LittleEndianWriter.WriteUInt16(buffer, offset + 40, Reserved);
+            LittleEndianWriter.WriteUInt16(buffer, offset + 42, (ushort)Flags);
+            LittleEndianWriter.WriteUInt64(buffer, offset + 44, SessionId);
+        }
+    }
+}
diff --git a/SMBLibrary/SMBLibrary.VS2005.csproj b/SMBLibrary/SMBLibrary.VS2005.csproj
index a35e8ee..8256a72 100644
--- a/SMBLibrary/SMBLibrary.VS2005.csproj
+++ b/SMBLibrary/SMBLibrary.VS2005.csproj
@@ -575,11 +575,13 @@
     <Compile Include="SMB2\Enums\SessionSetup\SessionSetupFlags.cs" />
     <Compile Include="SMB2\Enums\SMB2CommandName.cs" />
     <Compile Include="SMB2\Enums\SMB2PacketHeaderFlags.cs" />
+    <Compile Include="SMB2\Enums\SMB2TransformHeaderFlags.cs" />
     <Compile Include="SMB2\Enums\TreeConnect\ShareCapabilities.cs" />
     <Compile Include="SMB2\Enums\TreeConnect\ShareFlags.cs" />
     <Compile Include="SMB2\Enums\TreeConnect\ShareType.cs" />
     <Compile Include="SMB2\Enums\Write\WriteFlags.cs" />
     <Compile Include="SMB2\SMB2Header.cs" />
+    <Compile Include="SMB2\SMB2TransformHeader.cs" />
     <Compile Include="SMB2\Structures\CreateContext.cs" />
     <Compile Include="SMB2\Structures\Enums\LockFlags.cs" />
     <Compile Include="SMB2\Structures\FileID.cs" />