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@@ -5,3 +5,4 @@ | |
| .DS_Store | ||
| /build | ||
| *.iml | ||
| *.apk | ||
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54 changes: 54 additions & 0 deletions
54
...src/main/java/ru/esmukov/kpfu/lightningrodandroidvpnpoc/packetfilter/ByteBufferUtils.java
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| @@ -0,0 +1,54 @@ | ||
| package ru.esmukov.kpfu.lightningrodandroidvpnpoc.packetfilter; | ||
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| import java.nio.ByteBuffer; | ||
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| /** | ||
| * Created by kostya on 16/12/2016. | ||
| */ | ||
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| public class ByteBufferUtils { | ||
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| public static void moveLeft(ByteBuffer buffer, int shiftBytes) { | ||
| int length = buffer.limit(); | ||
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| for (int i = shiftBytes; i < length; i++) { | ||
| buffer.put(i - shiftBytes, buffer.get(i)); | ||
| } | ||
| buffer.position(0); | ||
| buffer.limit(length - shiftBytes); | ||
| } | ||
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| public static void moveRight(ByteBuffer buffer, int shiftBytes) { | ||
| int length = buffer.limit(); | ||
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| buffer.limit(length + shiftBytes); | ||
| for (int i = length - 1; i >= 0; i--) { | ||
| buffer.put(i + shiftBytes, buffer.get(i)); | ||
| } | ||
| buffer.position(0); | ||
| } | ||
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| public static void copy(ByteBuffer from, ByteBuffer to) { | ||
| to.limit(from.limit() + 1); // java.nio.BufferOverflowException | ||
| to.put(from.array(), 0, from.limit()); | ||
| to.limit(from.limit()); | ||
| to.position(0); | ||
| } | ||
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| public static void put6bytes(ByteBuffer byteBuffer, long l) { | ||
| // first byte | ||
| byteBuffer.put((byte) ((l >>> (8 * 5)) & 0xFF)); | ||
| // second byte | ||
| byteBuffer.put((byte) ((l >>> (8 * 4)) & 0xFF)); | ||
| // rest 4 bytes | ||
| byteBuffer.putInt((int) (l & 0xFFFFFFFFL)); | ||
| } | ||
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| public static long get6bytes(ByteBuffer byteBuffer) { | ||
| long l = 0; | ||
| l |= (long) (byteBuffer.get() & 0xFF) << (8 * 5); | ||
| l |= (long) (byteBuffer.get() & 0xFF) << (8 * 4); | ||
| l |= byteBuffer.getInt() & 0xFFFFFFFFL; | ||
| return l; | ||
| } | ||
| } |
38 changes: 38 additions & 0 deletions
38
app/src/main/java/ru/esmukov/kpfu/lightningrodandroidvpnpoc/packetfilter/PacketFilter.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,38 @@ | ||
| package ru.esmukov.kpfu.lightningrodandroidvpnpoc.packetfilter; | ||
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| import java.nio.ByteBuffer; | ||
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| /** | ||
| * Created by kostya on 16/12/2016. | ||
| */ | ||
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| /** | ||
| * Filter (and change, if needed) a packet between remote side and a local VpnService TUN. | ||
| */ | ||
| public interface PacketFilter { | ||
| /** | ||
| * Outgoing L3 IP4 packet | ||
| * | ||
| * @param ip4Packet Local IP4 packet. This method should convert this buffer | ||
| * to a format expected by the remote side | ||
| * @return Should the packet be sent? Drop it otherwise. | ||
| */ | ||
| boolean fromLocalToRemote(ByteBuffer ip4Packet); | ||
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| /** | ||
| * Incoming packet | ||
| * | ||
| * @param remotePacket This method should convert this raw packet received | ||
| * from the remote side to a local IP4 packet. | ||
| * @return Should the packet be accepted? Drop it otherwise. | ||
| */ | ||
| boolean fromRemoteToLocal(ByteBuffer remotePacket); | ||
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| /** | ||
| * Initiate custom outgoing packets | ||
| * | ||
| * @param remotePacket | ||
| * @return Is a packet to be sent put to the `remotePacket` buffer | ||
| */ | ||
| boolean nextCustomPacketToRemote(ByteBuffer remotePacket); | ||
| } |
76 changes: 76 additions & 0 deletions
76
app/src/main/java/ru/esmukov/kpfu/lightningrodandroidvpnpoc/packetfilter/PacketInfo.java
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,76 @@ | ||
| package ru.esmukov.kpfu.lightningrodandroidvpnpoc.packetfilter; | ||
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| import android.util.Log; | ||
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| import java.nio.ByteBuffer; | ||
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| /** | ||
| * Created by kostya on 06/01/2017. | ||
| */ | ||
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| public class PacketInfo { | ||
| private static final String TAG = "PacketInfo"; | ||
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| public static void prepend(ByteBuffer packet, int etherType) { | ||
| // todo looks like we don't need to ever set the TUN_PKT_STRIP flag, right? | ||
| // see: | ||
| // static ssize_t tun_put_user(struct tun_struct *tun, | ||
| // struct tun_file *tfile, | ||
| // struct sk_buff *skb, | ||
| // struct iov_iter *iter) | ||
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| // http://lxr.free-electrons.com/source/include/uapi/linux/if_ether.h | ||
| short flags = 0; | ||
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| ByteBufferUtils.moveRight(packet, 4); | ||
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| packet.putShort(0, flags); | ||
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| // Ethertype as per http://lxr.free-electrons.com/source/include/uapi/linux/if_ether.h | ||
| packet.putShort(2, (short) etherType); | ||
| } | ||
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| public static PacketInfoHeader strip(ByteBuffer remotePacket) throws Exception { | ||
| int length = remotePacket.limit(); | ||
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| if (length < 4) { | ||
| throw new Exception("packet with invalid length (<4)"); | ||
| } | ||
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| /* | ||
| struct tun_pi { | ||
| __u16 flags; | ||
| __be16 proto; | ||
| }; | ||
| */ | ||
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| int flags = ((remotePacket.get(0) & 0xFF) << 8) | (remotePacket.get(1) & 0xFF); | ||
| int proto = ((remotePacket.get(2) & 0xFF) << 8) | (remotePacket.get(3) & 0xFF); | ||
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| if (flags != 0) { | ||
| Log.w(TAG, "received non-zero flags: " + flags); | ||
| } | ||
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| // todo ?? check PI protocol as per | ||
| // static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile, | ||
| // void *msg_control, struct iov_iter *from, | ||
| // int noblock) | ||
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| ByteBufferUtils.moveLeft(remotePacket, 4); | ||
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| return new PacketInfoHeader(proto); | ||
| } | ||
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| public static class PacketInfoHeader { | ||
| private int mProto; | ||
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| private PacketInfoHeader(int mProto) { | ||
| this.mProto = mProto; | ||
| } | ||
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| public int getProto() { | ||
| return mProto; | ||
| } | ||
| } | ||
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| } |
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