https://github.com/refvalue/svchostify
Hosting your C#/Java/C++ project as a DLL service easily, NOT ONLY svchost.exe!
https://github.com/refvalue/svchostify
cpp csharp dll java svchost windows windowsservices
Last synced: 3 months ago
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Hosting your C#/Java/C++ project as a DLL service easily, NOT ONLY svchost.exe!
- Host: GitHub
- URL: https://github.com/refvalue/svchostify
- Owner: refvalue
- License: mit
- Created: 2024-11-29T09:54:43.000Z (6 months ago)
- Default Branch: main
- Last Pushed: 2025-02-20T14:06:59.000Z (4 months ago)
- Last Synced: 2025-03-23T10:45:54.819Z (3 months ago)
- Topics: cpp, csharp, dll, java, svchost, windows, windowsservices
- Language: C++
- Homepage:
- Size: 139 KB
- Stars: 1
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# SvcHostify: Hosting Your Own Codebase as A DLL Service Easily
## Motivation
`svchost.exe` is a critical system process for hosting DLLs as Windows Services, but some of its internal workings are undocumented. Creating custom `svchost` DLL services, especially when using languages like Java or C#, can be cumbersome. This is mainly due to the need for exporting C-style functions to interact with `svchost.exe`, which complicates the development process. To address this challenge, I created the "svchostify" project, which simplifies the creation of `svchost` DLL services, making it easier for developers to work with `svchost.exe` and supporting a wider range of programming languages.
## SvcHost Mode - For Personal Use
Microsoft states that `svchost.exe` is reserved for use by the operating system’s own services, so hosting as a SvcHost service is intended for academic and research purposes only, and might be used in personal environments. It is not recommended for use in production systems.
## Standalone Mode - For Production Use (NEW in [v0.1.1]())
This project provides a production-friendly mode, which allows it to run as a standalone service loaded by `rundll32.exe`, the operating system's DLL loader. This mode can be distributed without requiring any third-party executables. NVIDIA, for instance, uses this method to create its services.
**NOTE: This mode is set by default started in v0.1.1.**
## Prerequisites
The latest [Visual C++ Redistributable](https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist) is required for everything to function properly, only for x64 Windows.
## Downloading the Hosting DLL
This project provides a C++ dynamic library that enables hosting a DLL service, which can be registered to be loaded by `svchost.exe`. The latest compiled release can be found on the [Release](../../releases/) page. The default name for the prebuilt DLL is typically `svchostify.dll`. You can download and extract it to any location on your disk that you prefer.
## Command-Line Overview
The `svchostify.dll` is a self-executable library, meaning it can be directly loaded by `rundll32.exe`—the Windows tool used to run DLLs—by locating the C-style function entry specified by the user.
```powershell
rundll32 svchostify.dll invoke
```
Available options and arguments are listed below:
| Parameter | Description |
| --------------------- | ------------------------------------------------------------ |
| `--install`, `-i` | Installs the service. |
| `--uninstall`, `-u` | Uninstalls the service. |
| `--config-file`, `-c` | Specifies a configuration file that the installation or uninstallation is based on. |
| `--help`, `-h` | Displays details of the command line arguments. |
To install or uninstall a service, use:
```powershell
rundll32 svchostify.dll invoke -i -c
rundll32 svchostify.dll invoke -u -c
```
**NOTE: The configuration payload, along with the service metadata, will be written to the Windows Registry simultaneously, eliminating the need for a config file after installation.**
## JSON Configuration
The hosting service reads a JSON file for its internal configuration and the key-value pairs and objects are defined as follows:
| Field Name | Type | Description | Possible Values | Default | Required |
| -------------------------------------- | ----------------- | ------------------------------------------------------------ | ----------------------------------------------- | ---------------- | -------- |
| `workType` | `string` | The type of the service. | `com`, `pure_c`, `jvm`, `executable` | | Yes |
| `name` | `string` | The name of the service. | Any | | Yes |
| `displayName` | `string` | The display name of the service. | Any | | Yes |
| `context` | `string` | Arbitrary content according to the work type: a coclass `{GUID}` for `com`, a DLL path for `pure_c`, a `CLASSPATH` for `jvm`, an EXE path for `executable`. | Any | | Yes |
| `accountType` | `string` | The account type under which the service runs. | `localSystem`, `networkService`, `localService` | | Yes |
| `standalone`
**(NEW in v0.1.1)** | `boolean` | Indicates whether to run as a standalone service (hosted in `rundll32.exe`) instead of `svchost.exe` | `true`, `false` | `true` | No |
| `postQuitMessage` | `boolean` | Indicates whether to post a quit message before the service exits when the type is `executable`. | `true`, `false` | `false` | No |
| `description` | `string` | A description of the service. | Any | `null` | No |
| `jdkDirectory` | `string` | The JDK Directory. | Any valid directory path | `null` | No |
| `workingDirectory` | `string` | The initial working directory. | Any valid directory path | The DLL location | No |
| `arguments` | `array of string` | The startup arguments for the service. | `List of string` | `null` | No |
| `dllDirectories` | `array of string` | Additional directories for loading DLLs. | List of directories | The DLL location | No |
| `logger` | `object` | Logger configuration object. | See below | See below | No |
#### Logger Configuration Object
| Field Name | Type | Description | Possible Values | Default | Required |
| ---------- | -------- | ------------------------------------------------------------ | ------------------------------ | ------------------- | -------- |
| `basePath` | `string` | The base path of the logging file. | Any valid directory path | logs/svchostify.log | Yes |
| `maxSize` | `string` | The maximum size of one single log file. The pattern is `\d+\s*(KiB\|MiB\|GiB\|TiB)?`. | Any valid values like `10 MiB` | 50 MiB | No |
| `maxFiles` | `number` | The maximum count of log files. | Any positive integer | 5 | No |
**Note: The complete JSON schema can be found [here](svchostify.schema.json).**
## JSON Samples
### Hosting a JAR package
```json
{
"workerType": "jvm",
"name": "ABC_SomeTestSvc_Java",
"displayName": "ABC Test Java Service",
"context": "E:/Projects/SvcHostify/samples/svchost.jar",
"accountType": "networkService",
"standalone": true,
"description": "A Test Java Service for SvcHost.",
"jdkDirectory": "D:/jdk-21",
"workingDirectory": "D:/",
"arguments": [
"Hello",
"World"
],
"logger": {
"basePath": "logs/logger_java.log",
"maxSize": "10 MiB",
"maxFiles": 10
}
}
```
The sample project is [located here](samples/java/).
### Hosting a C# DLL implemented as an in-process COM server
```json
{
"workerType": "com",
"name": "ABC_MyTestSvc_CSharp",
"displayName": "ABC Test CSharp Service",
"context": "{47D7093F-69E2-D17D-422D-49BE836EF3A5}",
"accountType": "localSystem",
"standalone": true,
"description": "Test CSharp (Hosted as a COM server) Service for SvcHost.",
"workingDirectory": "D:/",
"arguments": [
"Hello",
"World"
],
"logger": {
"basePath": "logs/logger_csharp.log",
"maxSize": "10 MiB",
"maxFiles": 10
}
}
```
The sample project can be [checked here](samples/csharp/).
### Hosting a C++ DLL by calling exported pure C functions
```json
{
"workerType": "pureC",
"name": "ABC_MyTestSvc_CPP",
"displayName": "ABC Test C++ Service",
"context": "refvalue-test-service.dll",
"accountType": "localSystem",
"standalone": true,
"description": "Test C++ Service for SvcHost.",
"workingDirectory": "D:/",
"arguments": [
"Hello",
"World"
],
"logger": {
"basePath": "logs/logger_cpp.log",
"maxSize": "10 MiB",
"maxFiles": 10
}
}
```
The sample project is provided for [review here](samples/cpp/).
## Calling Conventions
| Programming Language | Calling Method |
| -------------------- | ------------------------------------------------------------ |
| Java | Implements `org.refvalue.SvcHostify` class with `static` methods `void run(String[] args)` and `void onStop()` |
| C# | Implements the COM interface `ISvcHostify` and its methods `void Run(string[] args)` and `void OnStop()` |
| C/C++ | Exports `extern "C"` functions `void refvalue_svchostify_run(std::size_t argc, const char* argv[])` and `void refvalue_svchostify_on_stop()` |
Some quick samples are provided in the `samples` directory. Feel free to [take a look](samples/)!
## Prototypes
### Java
```java
package org.refvalue;
import java.io.PrintStream;
import java.io.UnsupportedEncodingException;
import java.util.concurrent.atomic.AtomicBoolean;
public final class SvcHostify {
private static final AtomicBoolean running = new AtomicBoolean(false);
static {
try {
// Uses UTF-8 encoding all the way.
System.setOut(new PrintStream(System.out, true, "UTF-8"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}
/**
* The main routine of the service.
*
* @param args The input arguments.
*/
public static void run(String[] args) {
// The main loop of your service.
for (int i = 0; running.getAcquire(); i++) {
System.out.println(String.format("Hello service counter: %d", i));
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
System.out.println("Service has stopped from Java.");
}
/**
* This function will be called by the SvcHostify routine in another thread and
* you can, for example, send a signal to your 'run' routine to stop gracefully.
*/
public static void onStop() {
System.out.println("Requesting a stop.");
running.setRelease(false);
}
}
```
### C#
```csharp
using System.Runtime.InteropServices;
namespace Refvalue.Samples.SvcHost
{
[ComVisible(true)]
[Guid("47D7093F-69E2-D17D-422D-49BE836EF3A5")]
[ClassInterface(ClassInterfaceType.None)]
public class TestService : ISvcHostify
{
private int _running = 0;
///
/// The service entry point.
///
/// The input arguments
public void Run(string[] args)
{
Interlocked.Exchange(ref _running, 1);
for (int i = 0; Interlocked.CompareExchange(ref _running, 1, 1) == 1; i++)
{
Console.WriteLine($"Hello service counter: {i}");
Thread.Sleep(100);
}
Console.WriteLine("Service has stopped from CSharp.");
}
///
/// This function will be called by the SvcHostify routine in another thread and
/// you can, for example, send a signal to your 'Run' routine to stop gracefully.
///
public void OnStop()
{
Console.WriteLine("Requesting a stop.");
Interlocked.Exchange(ref _running, 0);
}
}
}
```
### C++
```cpp
#include
#include
#include
#include
#include
#include
namespace {
class test_service {
public:
test_service() : running_{false} {}
/**
* @brief The service entry point.
* @param argc The count of the arguments.
* @param argv The input arguments.
*/
void run(std::size_t argc, const char* argv[]) {
using std::chrono_literals::operator""ms;
running_.store(true, std::memory_order::release);
for (std::size_t i = 0; running_.load(std::memory_order::acquire); i++) {
std::cout << "Hello service counter: " << i << '\n';
std::this_thread::sleep_for(100ms);
}
}
/**
* This function will be called by the SvcHostify routine in another thread and,
* you can, for example, send a signal to your 'run' routine to stop gracefully.
*/
void on_stop() {
printf("Requesting a stop.\n");
running_.store(false, std::memory_order::release);
}
private:
std::atomic_bool running_;
};
test_service service;
} // namespace
extern "C" {
__declspec(dllexport) void refvalue_svchostify_run(std::size_t argc, const char* argv[]) try {
service.run(argc, argv);
} catch (std::exception& ex) {
std::cout << ex.what() << '\n';
}
__declspec(dllexport) void refvalue_svchostify_on_stop() try { service.on_stop(); } catch (std::exception& ex) {
std::cout << ex.what() << '\n';
}
}
```
## Logging Redirection
This system automatically redirects all output sent to `stdout` and `stderr` streams to a log file. It captures logs from various sources, including:
- **Java**: `System.out.println`
- **C#**: `Console.WriteLine`
- **C++**: `std::cout`, `spdlog`, `printf`and other standard output methods
The log file is continuously updated, with a new entry added every time the output exceeds 4 KB, ensuring that log data is refreshed at regular intervals. This redirection simplifies logging by consolidating output from multiple languages and libraries into a single, centralized log file for easier monitoring and troubleshooting.
## Exception Handling in Your Code
The hosting system automatically handles JNI exceptions as well as COM exceptions generated by the .NET Runtime. Throwing exceptions from Java code and the C# coclass implementation are **expected** behaviors. It's **NOT RECOMMENDED** to throw exceptions within the `pure_c` routines.
## LICENSE
This project is licensed under the MIT License.
You are free to use, modify, and distribute the software, including for commercial purposes, under the terms of the MIT License.
See the [LICENSE](LICENSE) file for more details.