1 files changed, 174 insertions, 0 deletions

diff --git a/app/src/main/java/org/pacien/tincapp/service/ConfigurationAccessService.kt b/app/src/main/java/org/pacien/tincapp/service/ConfigurationAccessService.kt
new file mode 100644
index 0000000..b083a83
--- /dev/null
+++ b/app/src/main/java/org/pacien/tincapp/service/ConfigurationAccessService.kt
@@ -0,0 +1,174 @@
+/*
+ * Tinc App, an Android binding and user interface for the tinc mesh VPN daemon
+ * Copyright (C) 2017-2020 Pacien TRAN-GIRARD
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.pacien.tincapp.service
+
+import android.app.PendingIntent
+import android.app.Service
+import android.content.Intent
+import android.os.IBinder
+import androidx.databinding.ObservableBoolean
+import ch.qos.logback.classic.Level
+import ch.qos.logback.classic.Logger
+import org.apache.ftpserver.FtpServer
+import org.apache.ftpserver.FtpServerFactory
+import org.apache.ftpserver.ftplet.*
+import org.apache.ftpserver.listener.ListenerFactory
+import org.apache.ftpserver.usermanager.UsernamePasswordAuthentication
+import org.apache.ftpserver.usermanager.impl.WritePermission
+import org.pacien.tincapp.R
+import org.pacien.tincapp.activities.configure.ConfigureActivity
+import org.pacien.tincapp.context.App
+import org.pacien.tincapp.context.AppNotificationManager
+import org.pacien.tincapp.extensions.Java.defaultMessage
+import org.slf4j.LoggerFactory
+import java.io.IOException
+
+/**
+ * FTP server service allowing a remote and local user to access and modify configuration files in
+ * the application's context.
+ *
+ * @author pacien
+ */
+class ConfigurationAccessService : Service() {
+  companion object {
+    // Apache Mina FtpServer's INFO log level is actually VERBOSE.
+    // The object holds static references to those loggers so that they stay around.
+    @Suppress("unused")
+    private val MINA_FTP_LOGGER_OVERRIDER = MinaLoggerOverrider(Level.WARN)
+
+    const val FTP_PORT = 65521 // tinc port `concat` FTP port
+    const val FTP_USERNAME = "tincapp"
+    val FTP_HOME_DIR = App.getContext().applicationInfo.dataDir!!
+    val FTP_PASSWORD = generateRandomString(8)
+
+    val runningState = ObservableBoolean(false)
+
+    private fun generateRandomString(length: Int): String {
+      val alphabet = ('a'..'z') + ('A'..'Z') + ('0'..'9')
+      return List(length) { alphabet.random() }.joinToString("")
+    }
+  }
+
+  private val log by lazy { LoggerFactory.getLogger(this.javaClass)!! }
+  private val notificationManager by lazy { App.notificationManager }
+  private var sftpServer: FtpServer? = null
+
+  override fun onBind(intent: Intent): IBinder? = null // non-bindable service
+
+  override fun onDestroy() {
+    sftpServer?.stop()
+    sftpServer = null
+    runningState.set(false)
+    log.info("Stopped FTP server")
+    super.onDestroy()
+  }
+
+  override fun onStartCommand(intent: Intent, flags: Int, startId: Int): Int {
+    val ftpUser = StaticFtpUser(FTP_USERNAME, FTP_PASSWORD, FTP_HOME_DIR, listOf(WritePermission()))
+    sftpServer = setupSingleUserServer(ftpUser).also {
+      try {
+        it.start()
+        runningState.set(true)
+        log.info("Started FTP server on port {}", FTP_PORT)
+        pinInForeground()
+      } catch (e: IOException) {
+        log.error("Could not start FTP server", e)
+        App.alert(R.string.notification_error_title_unable_to_start_ftp_server, e.defaultMessage())
+      }
+    }
+
+    return START_NOT_STICKY
+  }
+
+  /**
+   * Pins the service in the foreground so that it doesn't get stopped by the system when the
+   * application's activities are put in the background, which is the case when the user sets the
+   * focus on an FTP client app for example.
+   */
+  private fun pinInForeground() {
+    startForeground(
+      AppNotificationManager.CONFIG_ACCESS_NOTIFICATION_ID,
+      notificationManager.newConfigurationAccessNotificationBuilder()
+        .setSmallIcon(R.drawable.ic_baseline_folder_open_primary_24dp)
+        .setContentTitle(resources.getString(R.string.notification_config_access_server_running_title))
+        .setContentText(resources.getString(R.string.notification_config_access_server_running_message))
+        .setContentIntent(Intent(this, ConfigureActivity::class.java).let {
+          PendingIntent.getActivity(this, 0, it, 0)
+        })
+        .build()
+    )
+  }
+
+  private fun setupSingleUserServer(ftpUser: User): FtpServer {
+    return FtpServerFactory()
+      .apply { addListener("default", ListenerFactory().apply { port = FTP_PORT }.createListener()) }
+      .apply { userManager = StaticFtpUserManager(listOf(ftpUser)) }
+      .createServer()
+  }
+
+  private class StaticFtpUserManager(users: List<User>) : UserManager {
+    private val userMap: Map<String, User> = users.map { it.name to it }.toMap()
+    override fun getUserByName(username: String?): User? = userMap[username]
+    override fun getAllUserNames(): Array<String> = userMap.keys.toTypedArray()
+    override fun doesExist(username: String?): Boolean = username in userMap
+    override fun delete(username: String?) = throw UnsupportedOperationException()
+    override fun save(user: User?) = throw UnsupportedOperationException()
+    override fun getAdminName(): String = throw UnsupportedOperationException()
+    override fun isAdmin(username: String?): Boolean = throw UnsupportedOperationException()
+    override fun authenticate(authentication: Authentication?): User = when (authentication) {
+      is UsernamePasswordAuthentication -> getUserByName(authentication.username).let {
+        if (it != null && authentication.password == it.password) it
+        else throw AuthenticationFailedException()
+      }
+      else -> throw IllegalArgumentException()
+    }
+  }
+
+  private data class StaticFtpUser(
+    private val name: String,
+    private val password: String,
+    private val homeDirectory: String,
+    private val authorities: List<Authority>
+  ) : User {
+    override fun getName(): String = name
+    override fun getPassword(): String = password
+    override fun getAuthorities(): List<Authority> = authorities
+    override fun getAuthorities(clazz: Class<out Authority>): List<Authority> = authorities.filter(clazz::isInstance)
+    override fun getMaxIdleTime(): Int = 0 // unlimited
+    override fun getEnabled(): Boolean = true
+    override fun getHomeDirectory(): String = homeDirectory
+    override fun authorize(request: AuthorizationRequest?): AuthorizationRequest? =
+      authorities.filter { it.canAuthorize(request) }.fold(request) { req, auth -> auth.authorize(req) }
+  }
+
+  /**
+   * This registers package loggers filtering the output of the Mina FtpServer.
+   * The object holds static references to those loggers so that they stay around.
+   */
+  private class MinaLoggerOverrider(logLevel: Level) {
+    @Suppress("unused")
+    private val ftpServerLogger = forceLogLevel("org.apache.ftpserver", logLevel)
+
+    @Suppress("unused")
+    private val minaLogger = forceLogLevel("org.apache.mina", logLevel)
+
+    private fun forceLogLevel(pkgName: String, logLevel: Level) =
+      (LoggerFactory.getLogger(pkgName) as Logger).apply { level = logLevel }
+  }
+}