embeddable-dll-service: add basic outline for embedding wireguard

This allows people to embed WireGuard inside other apps as a service.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

3 files changed, 108 insertions, 0 deletions

diff --git a/embeddable-dll-service/README.md b/embeddable-dll-service/README.md
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+## Embeddable WireGuard Tunnel Library
+
+This allows embedding WireGuard as a service inside of another application. Build `tunnel.dll` by running `./build.bat` in this folder. The first time you run it, it will invoke `..\build.bat` simply for downloading dependencies. After, you should have `amd64/tunnel.dll` and `x86/tunnel.dll`.
+
+The basic setup to use `tunnel.dll` is:
+
+##### 1. Install a service with these parameters:
+
+    Service Name:  "SomeServiceName"
+    Display Name:  "Some Service Name"
+    Service Type:  SERVICE_WIN32_OWN_PROCESS
+    Start Type:    StartAutomatic
+    Error Control: ErrorNormal,
+    Dependencies:  [ "Nsi" ]
+    Sid Type:      SERVICE_SID_TYPE_UNRESTRICTED
+    Executable:    "C:\path\to\example\vpnclient.exe /service configfile.conf"
+
+Some of these may have to be changed with `ChangeServiceConfig2` after the
+initial call to `CreateService` The `SERVICE_SID_TYPE_UNRESTRICTED` parameter
+is absolutely essential; do not forget it.
+
+##### 2. Have your program's main function handle the `/service` switch:
+
+    if (!strcmp(argv[1], "/service") && argc == 3) {
+        HMODULE tunnel_lib = LoadLibrary("tunnel.dll");
+        if (!tunnel_lib)
+            abort();
+        tunnel_proc_t tunnel_proc = (tunnel_proc_t)GetProcAddress(tunnel_lib, "WireGuardTunnelService");
+        if (!tunnel_proc)
+            abort();
+        struct go_string conf_file = {
+            .str = argv[2],
+            .n = strlen(argv[2])
+        };
+        return tunnel_proc(conf_file);
+    }
+
+##### 3. Scoop up logs by implementing a ringlogger format reader.
+
+##### 4. Talk to the service over its named pipe.
diff --git a/embeddable-dll-service/build.bat b/embeddable-dll-service/build.bat
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+++ b/embeddable-dll-service/build.bat
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+@echo off
+rem SPDX-License-Identifier: MIT
+rem Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+
+setlocal
+set BUILDDIR=%~dp0
+set PATH=%BUILDDIR%..\.deps\go\bin;%BUILDDIR%..\.deps;%PATH%
+set PATHEXT=.exe
+cd /d %BUILDDIR% || exit /b 1
+
+if exist ..\.deps\prepared goto :build
+:installdeps
+	call ..\build.bat || goto :error
+
+:build
+	set GOOS=windows
+	set GOPATH=%BUILDDIR%..\.deps\gopath
+	set GOROOT=%BUILDDIR%..\.deps\go
+	set CGO_ENABLED=1
+	set CGO_CFLAGS=-O3 -Wall -Wno-unused-function -Wno-switch -std=gnu11 -DWINVER=0x0601
+	set CGO_LDFLAGS=-Wl,--major-os-version=6 -Wl,--minor-os-version=1 -Wl,--major-subsystem-version=6 -Wl,--minor-subsystem-version=1
+	call :build_plat x86 i686 386 || goto :error
+	call :build_plat amd64 x86_64 amd64 || goto :error
+
+:success
+	echo [+] Success
+	exit /b 0
+
+:build_plat
+	set PATH=%BUILDDIR%..\.deps\%~2-w64-mingw32-native\bin;%PATH%
+	set CC=%~2-w64-mingw32-gcc
+	set GOARCH=%~3
+	mkdir %1 >NUL 2>&1
+	echo [+] Building library %1
+	go build -buildmode c-shared -ldflags="-w -s" -trimpath -v -o "%~1/tunnel.dll" || exit /b 1
+	del "%~1\tunnel.h"
+	goto :eof
+
+:error
+	echo [-] Failed with error #%errorlevel%.
+	cmd /c exit %errorlevel%
diff --git a/embeddable-dll-service/main.go b/embeddable-dll-service/main.go
new file mode 100644
index 00000000..a8ce7c10
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+++ b/embeddable-dll-service/main.go
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+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
+ */
+
+package main
+
+import (
+	"C"
+	"golang.zx2c4.com/wireguard/windows/conf"
+	"golang.zx2c4.com/wireguard/windows/tunnel"
+	"log"
+	"path/filepath"
+)
+
+//export WireGuardTunnelService
+func WireGuardTunnelService(confFile string) bool {
+	conf.PresetRootDirectory(filepath.Dir(confFile))
+	tunnel.UseFixedGUIDInsteadOfDeterministic = true
+	err := tunnel.Run(confFile)
+	if err != nil {
+		log.Printf("Service run error: %v", err)
+	}
+	return err == nil
+}
+
+func main() {}