feat: add ChildProcessTracker

Netch/Controllers/HTTPController.cs

@@ -31,7 +31,10 @@ namespace Netch.Controllers
 
             try
             {
-                pPrivoxyController.Start(MainController.ServerController.Server, mode);
+                if (pPrivoxyController.Start(MainController.ServerController.Server, mode))
+                {
+                    ChildProcessTracker.AddProcess(pPrivoxyController.Instance);
+                }
 
                 if (mode.Type == 3) NativeMethods.SetGlobal($"127.0.0.1:{Global.Settings.HTTPLocalPort}", IEProxyExceptions);
             }

Netch/Controllers/MainController.cs

@@ -122,6 +122,14 @@ namespace Netch.Controllers
             Global.MainForm.StatusText(i18N.TranslateFormat("Starting {0}", controller.Name));
             if (controller.Start(in server, mode))
             {
+                if (controller is Guard guard)
+                {
+                    if (guard.Instance != null)
+                    {
+                        ChildProcessTracker.AddProcess(guard.Instance);
+                    }
+                }
+
                 UsingPorts.Add(StatusPortInfoText.Socks5Port = controller.Socks5LocalPort());
                 StatusPortInfoText.ShareLan = controller.LocalAddress == "0.0.0.0";
 
@@ -143,7 +151,20 @@ namespace Netch.Controllers
             if (ModeController != null)
             {
                 Global.MainForm.StatusText(i18N.TranslateFormat("Starting {0}", ModeController.Name));
-                return await Task.Run(() => ModeController.Start(mode));
+                if (await Task.Run(() => ModeController.Start(mode)))
+                {
+                    if (ModeController is Guard guard)
+                    {
+                        if (guard.Instance != null)
+                        {
+                            ChildProcessTracker.AddProcess(guard.Instance);
+                        }
+                    }
+
+                    return true;
+                }
+
+                return false;
             }
 
             return true;

Netch/Utils/ChildProcessTracker.cs

@@ -0,0 +1,145 @@
+using System;
+using System.ComponentModel;
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+
+namespace Netch.Utils
+{
+    /// <summary>
+    /// Allows processes to be automatically killed if this parent process unexpectedly quits.
+    /// This feature requires Windows 8 or greater. On Windows 7, nothing is done.</summary>
+    /// <remarks>References:
+    ///  https://stackoverflow.com/a/4657392/386091
+    ///  https://stackoverflow.com/a/9164742/386091 </remarks>
+    public static class ChildProcessTracker
+    {
+        /// <summary>
+        /// Add the process to be tracked. If our current process is killed, the child processes
+        /// that we are tracking will be automatically killed, too. If the child process terminates
+        /// first, that's fine, too.</summary>
+        /// <param name="process"></param>
+        public static void AddProcess(Process process)
+        {
+            if (s_jobHandle != IntPtr.Zero)
+            {
+                var success = AssignProcessToJobObject(s_jobHandle, process.Handle);
+                if (!success && !process.HasExited)
+                    throw new Win32Exception();
+            }
+        }
+
+        static ChildProcessTracker()
+        {
+            // This feature requires Windows 8 or later. To support Windows 7 requires
+            //  registry settings to be added if you are using Visual Studio plus an
+            //  app.manifest change.
+            //  https://stackoverflow.com/a/4232259/386091
+            //  https://stackoverflow.com/a/9507862/386091
+            /*if (Environment.OSVersion.Version < new Version(6, 2))
+                return;*/
+
+            // The job name is optional (and can be null) but it helps with diagnostics.
+            //  If it's not null, it has to be unique. Use SysInternals' Handle command-line
+            //  utility: handle -a ChildProcessTracker
+            var jobName = "ChildProcessTracker" + Process.GetCurrentProcess().Id;
+            s_jobHandle = CreateJobObject(IntPtr.Zero, jobName);
+
+            var info = new JOBOBJECT_BASIC_LIMIT_INFORMATION();
+
+            // This is the key flag. When our process is killed, Windows will automatically
+            //  close the job handle, and when that happens, we want the child processes to
+            //  be killed, too.
+            info.LimitFlags = JOBOBJECTLIMIT.JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE;
+
+            var extendedInfo = new JOBOBJECT_EXTENDED_LIMIT_INFORMATION
+            {
+                BasicLimitInformation = info
+            };
+
+            var length = Marshal.SizeOf(typeof(JOBOBJECT_EXTENDED_LIMIT_INFORMATION));
+            var extendedInfoPtr = Marshal.AllocHGlobal(length);
+            try
+            {
+                Marshal.StructureToPtr(extendedInfo, extendedInfoPtr, false);
+
+                if (!SetInformationJobObject(s_jobHandle, JobObjectInfoType.ExtendedLimitInformation,
+                    extendedInfoPtr, (uint) length))
+                {
+                    throw new Win32Exception();
+                }
+            }
+            finally
+            {
+                Marshal.FreeHGlobal(extendedInfoPtr);
+            }
+        }
+
+        [DllImport("kernel32.dll", CharSet = CharSet.Unicode)]
+        private static extern IntPtr CreateJobObject(IntPtr lpJobAttributes, string name);
+
+        [DllImport("kernel32.dll")]
+        private static extern bool SetInformationJobObject(IntPtr job, JobObjectInfoType infoType,
+            IntPtr lpJobObjectInfo, uint cbJobObjectInfoLength);
+
+        [DllImport("kernel32.dll", SetLastError = true)]
+        private static extern bool AssignProcessToJobObject(IntPtr job, IntPtr process);
+
+        // Windows will automatically close any open job handles when our process terminates.
+        //  This can be verified by using SysInternals' Handle utility. When the job handle
+        //  is closed, the child processes will be killed.
+        private static readonly IntPtr s_jobHandle;
+    }
+
+    public enum JobObjectInfoType
+    {
+        AssociateCompletionPortInformation = 7,
+        BasicLimitInformation = 2,
+        BasicUIRestrictions = 4,
+        EndOfJobTimeInformation = 6,
+        ExtendedLimitInformation = 9,
+        SecurityLimitInformation = 5,
+        GroupInformation = 11
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    public struct JOBOBJECT_BASIC_LIMIT_INFORMATION
+    {
+        public Int64 PerProcessUserTimeLimit;
+        public Int64 PerJobUserTimeLimit;
+        public JOBOBJECTLIMIT LimitFlags;
+        public UIntPtr MinimumWorkingSetSize;
+        public UIntPtr MaximumWorkingSetSize;
+        public UInt32 ActiveProcessLimit;
+        public Int64 Affinity;
+        public UInt32 PriorityClass;
+        public UInt32 SchedulingClass;
+    }
+
+    [Flags]
+    public enum JOBOBJECTLIMIT : uint
+    {
+        JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE = 0x2000
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    public struct IO_COUNTERS
+    {
+        public UInt64 ReadOperationCount;
+        public UInt64 WriteOperationCount;
+        public UInt64 OtherOperationCount;
+        public UInt64 ReadTransferCount;
+        public UInt64 WriteTransferCount;
+        public UInt64 OtherTransferCount;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    public struct JOBOBJECT_EXTENDED_LIMIT_INFORMATION
+    {
+        public JOBOBJECT_BASIC_LIMIT_INFORMATION BasicLimitInformation;
+        public IO_COUNTERS IoInfo;
+        public UIntPtr ProcessMemoryLimit;
+        public UIntPtr JobMemoryLimit;
+        public UIntPtr PeakProcessMemoryUsed;
+        public UIntPtr PeakJobMemoryUsed;
+    }
+}