From 2f376480f7a6fc8b5391f96b5b232f6a0489e88a Mon Sep 17 00:00:00 2001
From: M66B <marcel@faircode.eu>
Date: Thu, 7 Jan 2016 09:04:42 +0100
Subject: [PATCH] Decode IPv4 UDP packets

---
 .../main/java/eu/faircode/netguard/Packet.java  | 17 ++++++++++++++---
 .../eu/faircode/netguard/SinkholeService.java   |  3 +--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/app/src/main/java/eu/faircode/netguard/Packet.java b/app/src/main/java/eu/faircode/netguard/Packet.java
index 4fdf8abc..61b191f0 100644
--- a/app/src/main/java/eu/faircode/netguard/Packet.java
+++ b/app/src/main/java/eu/faircode/netguard/Packet.java
@@ -273,7 +273,18 @@ public class Packet {
 
     // https://en.wikipedia.org/wiki/User_Datagram_Protocol
     public class UDPHeader {
+        public int sourcePort;
+        public int destinationPort;
+        public int length;
+        public int checksum;
+
         public UDPHeader(ByteBuffer buffer) {
+            int pos = buffer.position();
+
+            this.sourcePort = buffer.getShort() & 0xFFFF;
+            this.destinationPort = buffer.getShort() & 0xFFFF;
+            this.length = buffer.getShort() & 0xFFFF;
+            this.checksum = buffer.getShort() & 0xFFFF;
         }
 
         public void validate() throws IOException {
@@ -492,15 +503,15 @@ public class Packet {
         }
     }
 
-    public int getUid4() {
-        if (this.TCP == null)
+    public int getUid() {
+        if (this.TCP == null && this.UDP == null)
             return -1;
 
         StringBuilder addr = new StringBuilder();
         byte[] b = this.IPv4.sourceAddress.getAddress();
         for (int i = b.length - 1; i >= 0; i--)
             addr.append(String.format("%02X", b[i]));
-        addr.append(':').append(String.format("%04X", this.TCP.sourcePort));
+        addr.append(':').append(String.format("%04X", this.TCP == null ? this.UDP.sourcePort : this.TCP.sourcePort));
 
         int uid = scanUid("0000000000000000FFFF0000" + addr.toString(), "/proc/net/tcp6");
         if (uid < 0)
diff --git a/app/src/main/java/eu/faircode/netguard/SinkholeService.java b/app/src/main/java/eu/faircode/netguard/SinkholeService.java
index 1dcda19f..fca7d363 100644
--- a/app/src/main/java/eu/faircode/netguard/SinkholeService.java
+++ b/app/src/main/java/eu/faircode/netguard/SinkholeService.java
@@ -63,7 +63,6 @@ import android.widget.RemoteViews;
 import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
-import java.net.Inet4Address;
 import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.nio.ByteBuffer;
@@ -708,7 +707,7 @@ public class SinkholeService extends VpnService {
                                             version,
                                             pkt.IPv4.destinationAddress.toString(),
                                             pkt.IPv4.protocol,
-                                            pkt.getUid4()).close();
+                                            pkt.getUid()).close();
 
                                 } else if (version == 6) {
                                     buffer.position(24);