Refactor code structure to split up files

Author: Mark Dietzer

PageantHandler.cs

@@ -0,0 +1,137 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace WslSSHPageant
+{
+    public class PageantException : Exception
+    {
+        internal PageantException(string message) : base(message)
+        {
+        }
+    }
+
+    static class PageantHandler
+    {
+        [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
+        static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
+
+        [DllImport("kernel32.dll")]
+        static extern uint GetCurrentThreadId();
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        public static extern IntPtr CreateFileMapping(
+            IntPtr hFile,
+            IntPtr lpFileMappingAttributes,
+            FileMapProtection flProtect,
+            uint dwMaximumSizeHigh,
+            uint dwMaximumSizeLow,
+            string lpName);
+
+        [Flags]
+        public enum FileMapProtection : uint
+        {
+            PageReadonly = 0x02,
+            PageReadWrite = 0x04,
+            PageWriteCopy = 0x08,
+            PageExecuteRead = 0x20,
+            PageExecuteReadWrite = 0x40,
+            SectionCommit = 0x8000000,
+            SectionImage = 0x1000000,
+            SectionNoCache = 0x10000000,
+            SectionReserve = 0x4000000,
+        }
+
+        static readonly IntPtr INVALID_HANDLE_VALUE = new IntPtr(-1);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        static extern IntPtr MapViewOfFile(
+            IntPtr hFileMappingObject,
+            FileMapAccess dwDesiredAccess,
+            UInt32 dwFileOffsetHigh,
+            UInt32 dwFileOffsetLow,
+            UIntPtr dwNumberOfBytesToMap);
+
+        [Flags]
+        public enum FileMapAccess : uint
+        {
+            FileMapCopy = 0x0001,
+            FileMapWrite = 0x0002,
+            FileMapRead = 0x0004,
+            FileMapAllAccess = 0x001f,
+            FileMapExecute = 0x0020,
+        }
+
+        [DllImport("user32.dll")]
+        static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);
+
+        [StructLayout(LayoutKind.Sequential)]
+        struct COPYDATASTRUCT
+        {
+            public IntPtr dwData;    // Any value the sender chooses.  Perhaps its main window handle?
+            public int cbData;       // The count of bytes in the message.
+            public IntPtr lpData;    // The address of the message.
+        }
+
+        const int WM_COPYDATA = 0x004A;
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        static extern bool UnmapViewOfFile(IntPtr lpBaseAddress);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        static extern bool CloseHandle(IntPtr hHandle);
+
+        internal const uint AGENT_MAX_MSGLEN = 8192;
+        static readonly IntPtr AGENT_COPYDATA_ID = new IntPtr(0x804e50ba);
+
+        // Send ssh-agent query to Pageant, ssh-agent and Pageant use same messages
+        internal static byte[] Query(ArraySegment<byte> buf)
+        {
+            var hwnd = FindWindowByCaption(IntPtr.Zero, "Pageant");
+            if (hwnd == IntPtr.Zero)
+            {
+                throw new PageantException("HWND not found");
+            }
+
+            var mapName = String.Format("PageantRequest{0:x8}", GetCurrentThreadId());
+            var fileMap = CreateFileMapping(INVALID_HANDLE_VALUE, IntPtr.Zero, FileMapProtection.PageReadWrite, 0, AGENT_MAX_MSGLEN, mapName);
+            var sharedMemory = MapViewOfFile(fileMap, FileMapAccess.FileMapWrite, 0, 0, UIntPtr.Zero);
+            Marshal.Copy(buf.Array, buf.Offset, sharedMemory, buf.Count);
+
+            var mapNameBytes = Encoding.UTF8.GetBytes(mapName + '\0');
+            var gch = GCHandle.Alloc(mapNameBytes);
+
+            var cds = new COPYDATASTRUCT();
+            cds.dwData = AGENT_COPYDATA_ID;
+            cds.cbData = mapNameBytes.Length;
+            cds.lpData = Marshal.UnsafeAddrOfPinnedArrayElement(mapNameBytes, 0);
+
+            var data = Marshal.AllocHGlobal(Marshal.SizeOf(cds));
+            Marshal.StructureToPtr(cds, data, false);
+            var rcode = SendMessage(hwnd, WM_COPYDATA, IntPtr.Zero, data);
+            if (rcode == IntPtr.Zero)
+            {
+                throw new PageantException("WM_COPYDATA failed");
+            }
+
+            var len = (Marshal.ReadByte(sharedMemory, 0) << 24) |
+                      (Marshal.ReadByte(sharedMemory, 1) << 16) |
+                      (Marshal.ReadByte(sharedMemory, 2) << 8) |
+                      (Marshal.ReadByte(sharedMemory, 3));
+
+            len += 4;
+            if (len > AGENT_MAX_MSGLEN)
+            {
+                throw new PageantException("Message too long");
+            }
+
+            var ret = new byte[len];
+            Marshal.Copy(sharedMemory, ret, 0, len);
+
+            UnmapViewOfFile(sharedMemory);
+            CloseHandle(fileMap);
+
+            return ret;
+        }
+    }
+}