Fix arp scanner for devices without /proc/net/arp

fixes #1
csicar · Aug 13, 2020 · 88d6377 · 88d6377
1 parent 51a2c58
commit 88d6377
Showing 1 changed file with 29 additions and 16 deletions.
diff --git a/app/src/main/java/de/csicar/ning/scanner/ArpScanner.kt b/app/src/main/java/de/csicar/ning/scanner/ArpScanner.kt
@@ -6,6 +6,8 @@ import kotlinx.coroutines.async
 import kotlinx.coroutines.awaitAll
 import kotlinx.coroutines.withContext
 import java.io.File
+import java.io.FileNotFoundException
+import java.io.IOException
 import java.io.InputStream
 import java.net.InetAddress
 import java.util.regex.Pattern
@@ -46,24 +48,35 @@ object ArpScanner {
 
     }
 
-    private suspend fun getArpTableFromFile() = withContext(Dispatchers.IO) {
-        File("/proc/net/arp").inputStream().readStreamAsTable()
-            .drop(1)
-            .filter { it.size == 6 }
-            .map {
-                ArpEntry.from(it[0], it[3])
-            }
+    private suspend fun getArpTableFromFile() : Sequence<ArpEntry> = withContext(Dispatchers.IO) {
+        try {
+            File("/proc/net/arp").inputStream().readStreamAsTable()
+                .drop(1)
+                .filter { it.size == 6 }
+                .map {
+                    ArpEntry.from(it[0], it[3])
+                }
+        } catch (exception : FileNotFoundException) {
+            Log.e("arp-scanner", "arp file not found $exception")
+            emptySequence<ArpEntry>()
+        }
     }
 
-    private suspend fun getArpTableFromIpCommand() = withContext(Dispatchers.IO) {
-        val execution = Runtime.getRuntime().exec("ip neigh")
-        execution.waitFor()
-        execution.inputStream.readStreamAsTable()
-            .filter { it.size >= 5 }
-            .map {
-                ArpEntry.from(it[0], it[4])
-            }
-            .onEach { Log.d("asd", "found entry in 'ip neight': $it") }
+    private suspend fun getArpTableFromIpCommand() : Sequence<ArpEntry> = withContext(Dispatchers.IO) {
+        try {
+
+            val execution = Runtime.getRuntime().exec("ip neigh")
+            execution.waitFor()
+            execution.inputStream.readStreamAsTable()
+                .filter { it.size >= 5 }
+                .map {
+                    ArpEntry.from(it[0], it[4])
+                }
+                .onEach { Log.d("arp-scanner", "found entry in 'ip neight': $it") }
+        } catch (exception: IOException) {
+            Log.e("arp-scanner", "io error when running ip neigh $exception")
+            emptySequence<ArpEntry>()
+        }
     }
 }