feat: Implement basic Yggdrasil service

app/src/main/java/io/github/chronosx88/yggdrasil/Constants.kt

@@ -0,0 +1,3 @@
+package io.github.chronosx88.yggdrasil
+
+const val YGGDRASIL_VERSION = "0.3.7"

app/src/main/java/io/github/chronosx88/yggdrasil/Utils.kt

@@ -0,0 +1,11 @@
+package io.github.chronosx88.yggdrasil
+
+import android.content.Context
+import java.io.File
+import java.lang.Runtime.getRuntime
+
+val Context.yggBin get() = File(filesDir, "yggdrasil-0.3.7")
+
+fun Context.execYgg(cmd: String) = getRuntime().exec(
+    "${yggBin.absolutePath} $cmd"
+)

app/src/main/java/io/github/chronosx88/yggdrasil/YggdrasilService.kt

@@ -0,0 +1,69 @@
+package io.github.chronosx88.yggdrasil
+
+import android.app.Service
+import android.content.Intent
+import android.os.Build.CPU_ABI
+import android.util.Log
+import kotlin.system.exitProcess
+
+class YggdrasilService : Service() {
+    private val LOG_TAG: String = YggdrasilService::class.java.simpleName
+
+    override fun onBind(intent: Intent) = null
+
+    companion object {
+        var daemon: Process? = null
+    }
+
+    private fun installBinary() {
+        val type = CPU_ABI.let {
+            when{
+                it.contains("v8") -> "arm64"
+                it.contains("v7") -> "armhf"
+                else -> throw Exception("Unsupported ABI")
+            }
+        }
+
+        yggBin.apply {
+            delete()
+            createNewFile()
+        }
+
+        val input = assets.open(type)
+        val output = yggBin.outputStream()
+
+        try {
+            input.copyTo(output)
+        } finally {
+            input.close(); output.close()
+        }
+
+        yggBin.setExecutable(true)
+        execYgg("-genconf > yggdrasil.conf").waitFor() // Generate config
+        Log.i(LOG_TAG, "# Binary installed successfully")
+    }
+
+    private fun start() {
+        execYgg("-useconffile yggdrasil.conf").apply {
+            daemon = this
+        }
+    }
+
+    private fun stop() {
+        daemon?.destroy()
+        daemon = null
+    }
+
+    override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
+        super.onStartCommand(intent, flags, startId)
+        when (intent?.action) {
+            "start" -> start()
+            "stop" -> stop()
+            "restart" -> {
+                stop(); start()
+            }
+            "exit" -> exitProcess(0)
+        }
+        return START_STICKY
+    }
+}