1 files changed, 104 insertions, 0 deletions
diff --git a/trackersserviceeos/src/main/java/foundation/e/advancedprivacy/trackers/service/DNSBlocker.kt b/trackersserviceeos/src/main/java/foundation/e/advancedprivacy/trackers/service/DNSBlocker.kt
new file mode 100644
index 0000000..6a2b218
--- /dev/null
+++ b/trackersserviceeos/src/main/java/foundation/e/advancedprivacy/trackers/service/DNSBlocker.kt
@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2023 MURENA SAS
+ * Copyright (C) 2022 E FOUNDATION
+ *
+ * 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 foundation.e.advancedprivacy.trackers.service
+
+import android.net.LocalServerSocket
+import android.system.ErrnoException
+import android.system.Os
+import android.system.OsConstants
+import foundation.e.advancedprivacy.core.utils.runSuspendCatching
+import foundation.e.advancedprivacy.trackers.domain.usecases.FilterHostnameUseCase
+import kotlinx.coroutines.CancellationException
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import timber.log.Timber
+import java.io.BufferedReader
+import java.io.InputStreamReader
+import java.io.PrintWriter
+
+class DNSBlocker(
+    val filterHostnameUseCase: FilterHostnameUseCase
+) {
+    private var resolverReceiver: LocalServerSocket? = null
+
+    companion object {
+        private const val SOCKET_NAME = "foundation.e.advancedprivacy"
+    }
+
+    private fun closeSocket() {
+        // Known bug and workaround that LocalServerSocket::close is not working well
+        // https://issuetracker.google.com/issues/36945762
+        if (resolverReceiver != null) {
+            try {
+                Os.shutdown(resolverReceiver!!.fileDescriptor, OsConstants.SHUT_RDWR)
+                resolverReceiver!!.close()
+                resolverReceiver = null
+            } catch (e: ErrnoException) {
+                if (e.errno != OsConstants.EBADF) {
+                    Timber.w("Socket already closed")
+                } else {
+                    Timber.e(e, "Exception: cannot close DNS port on stop $SOCKET_NAME !")
+                }
+            } catch (e: Exception) {
+                Timber.e(e, "Exception: cannot close DNS port on stop $SOCKET_NAME !")
+            }
+        }
+    }
+
+    fun listenJob(scope: CoroutineScope): Job = scope.launch(Dispatchers.IO) {
+        val resolverReceiver = runSuspendCatching {
+            LocalServerSocket(SOCKET_NAME)
+        }.getOrElse {
+            Timber.e(it, "Exception: cannot open DNS port on $SOCKET_NAME")
+            return@launch
+        }
+
+        this@DNSBlocker.resolverReceiver = resolverReceiver
+        Timber.d("DNSFilterProxy running on port $SOCKET_NAME")
+
+        while (isActive) {
+            runSuspendCatching {
+                val socket = resolverReceiver.accept()
+                val reader = BufferedReader(InputStreamReader(socket.inputStream))
+                val line = reader.readLine()
+                val params = line.split(",").toTypedArray()
+                val output = socket.outputStream
+                val writer = PrintWriter(output, true)
+                val domainName = params[0]
+                val appUid = params[1].toInt()
+                if (filterHostnameUseCase.shouldBlock(domainName, appUid)) {
+                    writer.println("block")
+                } else {
+                    writer.println("pass")
+                }
+                socket.close()
+            }.onFailure {
+                if (it is CancellationException) {
+                    closeSocket()
+                    throw it
+                } else {
+                    Timber.w(it, "Exception while listening DNS resolver")
+                }
+            }
+        }
+    }
+}