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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.testutils;
import android.os.Handler;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.android.net.module.util.ArrayTrackRecord;
import com.android.net.module.util.PacketReader;
import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.function.Predicate;
import kotlin.Lazy;
import kotlin.LazyKt;
/**
* A packet reader that runs on a TAP interface.
*
* It also implements facilities to reply to received packets.
*/
public class TapPacketReader extends PacketReader {
private final FileDescriptor mTapFd;
private final ArrayTrackRecord<byte[]> mReceivedPackets = new ArrayTrackRecord<>();
private final Lazy<ArrayTrackRecord<byte[]>.ReadHead> mReadHead =
LazyKt.lazy(mReceivedPackets::newReadHead);
public TapPacketReader(Handler h, FileDescriptor tapFd, int maxPacketSize) {
super(h, maxPacketSize);
mTapFd = tapFd;
}
/**
* Attempt to start the FdEventsReader on its handler thread.
*
* As opposed to {@link android.net.util.FdEventsReader#start()}, this method will not report
* failure to start, so it is only appropriate in tests that will fail later if that happens.
*/
public void startAsyncForTest() {
getHandler().post(this::start);
}
@Override
protected FileDescriptor createFd() {
return mTapFd;
}
@Override
protected void handlePacket(byte[] recvbuf, int length) {
final byte[] newPacket = Arrays.copyOf(recvbuf, length);
if (!mReceivedPackets.add(newPacket)) {
throw new AssertionError("More than " + Integer.MAX_VALUE + " packets outstanding!");
}
}
/**
* @deprecated This method does not actually "pop" (which generally means the last packet).
* Use {@link #poll(long)}, which has the same behavior, instead.
*/
@Nullable
@Deprecated
public byte[] popPacket(long timeoutMs) {
return poll(timeoutMs);
}
/**
* @deprecated This method does not actually "pop" (which generally means the last packet).
* Use {@link #poll(long, Predicate)}, which has the same behavior, instead.
*/
@Nullable
@Deprecated
public byte[] popPacket(long timeoutMs, @NonNull Predicate<byte[]> filter) {
return poll(timeoutMs, filter);
}
/**
* Get the next packet that was received on the interface.
*/
@Nullable
public byte[] poll(long timeoutMs) {
return mReadHead.getValue().poll(timeoutMs, packet -> true);
}
/**
* Get the next packet that was received on the interface and matches the specified filter.
*/
@Nullable
public byte[] poll(long timeoutMs, @NonNull Predicate<byte[]> filter) {
return mReadHead.getValue().poll(timeoutMs, filter::test);
}
/**
* Get the {@link ArrayTrackRecord} that records all packets received by the reader since its
* creation.
*/
public ArrayTrackRecord<byte[]> getReceivedPackets() {
return mReceivedPackets;
}
/*
* Send a response on the TAP interface.
*
* The passed ByteBuffer is flipped after use.
*
* @param packet The packet to send.
* @throws IOException if the interface can't be written to.
*/
public void sendResponse(final ByteBuffer packet) throws IOException {
try (FileOutputStream out = new FileOutputStream(mTapFd)) {
byte[] packetBytes = new byte[packet.limit()];
packet.get(packetBytes);
packet.flip(); // So we can reuse it in the future.
out.write(packetBytes);
}
}
}
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