Remove NAPT from PacketForwarder am: 74acb88d03
Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2901358
Change-Id: Ib7e74b2b2ce9194f3028f29ffb2ca52901ddf259
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/NatExternalPacketForwarder.kt b/staticlibs/testutils/devicetests/com/android/testutils/NatExternalPacketForwarder.kt
deleted file mode 100644
index d7961a0..0000000
--- a/staticlibs/testutils/devicetests/com/android/testutils/NatExternalPacketForwarder.kt
+++ /dev/null
@@ -1,81 +0,0 @@
-/*
- * Copyright (C) 2023 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 java.io.FileDescriptor
-import java.net.InetAddress
-
-/**
- * A class that forwards packets from the external {@link TestNetworkInterface} to the internal
- * {@link TestNetworkInterface} with NAT. See {@link NatPacketForwarderBase} for detail.
- */
-class NatExternalPacketForwarder(
- srcFd: FileDescriptor,
- mtu: Int,
- dstFd: FileDescriptor,
- extAddr: InetAddress,
- natMap: PacketBridge.NatMap
-) : NatPacketForwarderBase(srcFd, mtu, dstFd, extAddr, natMap) {
-
- /**
- * Rewrite addresses, ports and fix up checksums for packets received on the external
- * interface.
- *
- * Incoming response from external interface which is being forwarded to the internal
- * interface with translated address, e.g. 1.2.3.4:80 -> 8.8.8.8:1234
- * will be translated into 8.8.8.8:80 -> 192.168.1.1:5678.
- *
- * For packets that are not an incoming response, do not forward them to the
- * internal interface.
- */
- override fun preparePacketForForwarding(buf: ByteArray, len: Int, version: Int, proto: Int) {
- val (addrPos, addrLen) = getAddressPositionAndLength(version)
-
- // TODO: support one external address per ip version.
- val extAddrBuf = mExtAddr.address
- if (addrLen != extAddrBuf.size) throw IllegalStateException("Packet IP version mismatch")
-
- // Get internal address by port.
- val transportOffset =
- if (version == 4) PacketReflector.IPV4_HEADER_LENGTH
- else PacketReflector.IPV6_HEADER_LENGTH
- val dstPort = getPortAt(buf, transportOffset + DESTINATION_PORT_OFFSET)
- val intAddrInfo = synchronized(mNatMap) { mNatMap.fromExternalPort(dstPort) }
- // No mapping, skip. This usually happens if the connection is initiated directly on
- // the external interface, e.g. DNS64 resolution, network validation, etc.
- if (intAddrInfo == null) return
-
- val intAddrBuf = intAddrInfo.address.address
- val intPort = intAddrInfo.port
-
- // Copy the original destination to into the source address.
- for (i in 0 until addrLen) {
- buf[addrPos + i] = buf[addrPos + addrLen + i]
- }
-
- // Copy the internal address into the destination address.
- for (i in 0 until addrLen) {
- buf[addrPos + addrLen + i] = intAddrBuf[i]
- }
-
- // Copy the internal port into the destination port.
- setPortAt(intPort, buf, transportOffset + DESTINATION_PORT_OFFSET)
-
- // Fix IP and Transport layer checksum.
- fixPacketChecksum(buf, len, version, proto.toByte())
- }
-}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/NatInternalPacketForwarder.kt b/staticlibs/testutils/devicetests/com/android/testutils/NatInternalPacketForwarder.kt
deleted file mode 100644
index fa39d19..0000000
--- a/staticlibs/testutils/devicetests/com/android/testutils/NatInternalPacketForwarder.kt
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- * Copyright (C) 2023 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 java.io.FileDescriptor
-import java.net.InetAddress
-
-/**
- * A class that forwards packets from the internal {@link TestNetworkInterface} to the external
- * {@link TestNetworkInterface} with NAT. See {@link NatPacketForwarderBase} for detail.
- */
-class NatInternalPacketForwarder(
- srcFd: FileDescriptor,
- mtu: Int,
- dstFd: FileDescriptor,
- extAddr: InetAddress,
- natMap: PacketBridge.NatMap
-) : NatPacketForwarderBase(srcFd, mtu, dstFd, extAddr, natMap) {
-
- /**
- * Rewrite addresses, ports and fix up checksums for packets received on the internal
- * interface.
- *
- * Outgoing packet from the internal interface which is being forwarded to the
- * external interface with translated address, e.g. 192.168.1.1:5678 -> 8.8.8.8:80
- * will be translated into 8.8.8.8:1234 -> 1.2.3.4:80.
- *
- * The external port, e.g. 1234 in the above example, is the port number assigned by
- * the forwarder when creating the mapping to identify the source address and port when
- * the response is coming from the external interface. See {@link PacketBridge.NatMap}
- * for detail.
- */
- override fun preparePacketForForwarding(buf: ByteArray, len: Int, version: Int, proto: Int) {
- val (addrPos, addrLen) = getAddressPositionAndLength(version)
-
- // TODO: support one external address per ip version.
- val extAddrBuf = mExtAddr.address
- if (addrLen != extAddrBuf.size) throw IllegalStateException("Packet IP version mismatch")
-
- val srcAddr = getInetAddressAt(buf, addrPos, addrLen)
-
- // Copy the original destination to into the source address.
- for (i in 0 until addrLen) {
- buf[addrPos + i] = buf[addrPos + addrLen + i]
- }
-
- // Copy the external address into the destination address.
- for (i in 0 until addrLen) {
- buf[addrPos + addrLen + i] = extAddrBuf[i]
- }
-
- // Add an entry to NAT mapping table.
- val transportOffset =
- if (version == 4) PacketReflector.IPV4_HEADER_LENGTH
- else PacketReflector.IPV6_HEADER_LENGTH
- val srcPort = getPortAt(buf, transportOffset)
- val extPort = synchronized(mNatMap) { mNatMap.toExternalPort(srcAddr, srcPort, proto) }
- // Copy the external port to into the source port.
- setPortAt(extPort, buf, transportOffset)
-
- // Fix IP and Transport layer checksum.
- fixPacketChecksum(buf, len, version, proto.toByte())
- }
-}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt b/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
index d50f78a..0d0cc06 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketBridge.kt
@@ -16,6 +16,7 @@
package com.android.testutils
+import android.annotation.SuppressLint
import android.content.Context
import android.net.ConnectivityManager
import android.net.LinkAddress
@@ -31,29 +32,27 @@
import java.net.InetAddress
import libcore.io.IoUtils
-private const val MIN_PORT_NUMBER = 1025
-private const val MAX_PORT_NUMBER = 65535
-
/**
- * A class that set up two {@link TestNetworkInterface} with NAT, and forward packets between them.
+ * A class that set up two {@link TestNetworkInterface}, and forward packets between them.
*
- * See {@link NatPacketForwarder} for more detailed information.
+ * See {@link PacketForwarder} for more detailed information.
*/
+// TODO: Support multiple addresses.
class PacketBridge(
context: Context,
- internalAddr: LinkAddress,
- externalAddr: LinkAddress,
+ address: LinkAddress,
dnsAddr: InetAddress
) {
- private val natMap = NatMap()
private val binder = Binder()
private val cm = context.getSystemService(ConnectivityManager::class.java)!!
private val tnm = context.getSystemService(TestNetworkManager::class.java)!!
- // Create test networks.
- private val internalIface = tnm.createTunInterface(listOf(internalAddr))
- private val externalIface = tnm.createTunInterface(listOf(externalAddr))
+ // Create test networks. The needed permissions should be supplied by the callers.
+ @SuppressLint("MissingPermission")
+ private val internalIface = tnm.createTunInterface(listOf(address))
+ @SuppressLint("MissingPermission")
+ private val externalIface = tnm.createTunInterface(listOf(address))
// Register test networks to ConnectivityService.
private val internalNetworkCallback: TestableNetworkCallback
@@ -61,32 +60,20 @@
val internalNetwork: Network
val externalNetwork: Network
init {
- val (inCb, inNet) = createTestNetwork(internalIface, internalAddr, dnsAddr)
- val (exCb, exNet) = createTestNetwork(externalIface, externalAddr, dnsAddr)
+ val (inCb, inNet) = createTestNetwork(internalIface, address, dnsAddr)
+ val (exCb, exNet) = createTestNetwork(externalIface, address, dnsAddr)
internalNetworkCallback = inCb
externalNetworkCallback = exCb
internalNetwork = inNet
externalNetwork = exNet
}
- // Setup the packet bridge.
+ // Set up the packet bridge.
private val internalFd = internalIface.fileDescriptor.fileDescriptor
private val externalFd = externalIface.fileDescriptor.fileDescriptor
- private val pr1 = NatInternalPacketForwarder(
- internalFd,
- 1500,
- externalFd,
- externalAddr.address,
- natMap
- )
- private val pr2 = NatExternalPacketForwarder(
- externalFd,
- 1500,
- internalFd,
- externalAddr.address,
- natMap
- )
+ private val pr1 = PacketForwarder(internalFd, 1500, externalFd)
+ private val pr2 = PacketForwarder(externalFd, 1500, internalFd)
fun start() {
IoUtils.setBlocking(internalFd, true /* blocking */)
@@ -130,44 +117,4 @@
val network = testCb.expect<Available>().network
return testCb to network
}
-
- /**
- * A helper class to maintain the mappings between internal addresses/ports and external
- * ports.
- *
- * This class assigns an unused external port number if the mapping between
- * srcaddress:srcport:protocol and the external port does not exist yet.
- *
- * Note that this class is not thread-safe. The instance of the class needs to be
- * synchronized in the callers when being used in multiple threads.
- */
- class NatMap {
- data class AddressInfo(val address: InetAddress, val port: Int, val protocol: Int)
-
- private val mToExternalPort = HashMap<AddressInfo, Int>()
- private val mFromExternalPort = HashMap<Int, AddressInfo>()
-
- // Skip well-known port 0~1024.
- private var nextExternalPort = MIN_PORT_NUMBER
-
- fun toExternalPort(addr: InetAddress, port: Int, protocol: Int): Int {
- val info = AddressInfo(addr, port, protocol)
- val extPort: Int
- if (!mToExternalPort.containsKey(info)) {
- extPort = nextExternalPort++
- if (nextExternalPort > MAX_PORT_NUMBER) {
- throw IllegalStateException("Available ports are exhausted")
- }
- mToExternalPort[info] = extPort
- mFromExternalPort[extPort] = info
- } else {
- extPort = mToExternalPort[info]!!
- }
- return extPort
- }
-
- fun fromExternalPort(port: Int): AddressInfo? {
- return mFromExternalPort[port]
- }
- }
}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/NatPacketForwarderBase.java b/staticlibs/testutils/devicetests/com/android/testutils/PacketForwarder.java
similarity index 62%
rename from staticlibs/testutils/devicetests/com/android/testutils/NatPacketForwarderBase.java
rename to staticlibs/testutils/devicetests/com/android/testutils/PacketForwarder.java
index 0a2b5d4..d8efb7d 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/NatPacketForwarderBase.java
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketForwarder.java
@@ -30,16 +30,13 @@
import android.system.Os;
import android.util.Log;
-import androidx.annotation.GuardedBy;
-
import java.io.FileDescriptor;
import java.io.IOException;
-import java.net.InetAddress;
import java.util.Objects;
/**
* A class that forwards packets from a {@link TestNetworkInterface} to another
- * {@link TestNetworkInterface} with NAT.
+ * {@link TestNetworkInterface}.
*
* For testing purposes, a {@link TestNetworkInterface} provides a {@link FileDescriptor}
* which allows content injection on the test network. However, this could be hard to use
@@ -54,30 +51,14 @@
*
* To make it work, an internal interface and an external interface are defined, where
* the client might send packets from the internal interface which are originated from
- * multiple addresses to a server that listens on the external address.
- *
- * When forwarding the outgoing packet on the internal interface, a simple NAT mechanism
- * is implemented during forwarding, which will swap the source and destination,
- * but replacing the source address with the external address,
- * e.g. 192.168.1.1:1234 -> 8.8.8.8:80 will be translated into 8.8.8.8:1234 -> 1.2.3.4:80.
- *
- * For the above example, a client who sends http request will have a hallucination that
- * it is talking to a remote server at 8.8.8.8. Also, the server listens on 1.2.3.4 will
- * have a different hallucination that the request is sent from a remote client at 8.8.8.8,
- * to a local address 1.2.3.4.
- *
- * And a NAT mapping is created at the time when the outgoing packet is forwarded.
- * With a different internal source port, the instance learned that when a response with the
- * destination port 1234, it should forward the packet to the internal address 192.168.1.1.
+ * multiple addresses to a server that listens on the different port.
*
* For the incoming packet received from external interface, for example a http response sent
* from the http server, the same mechanism is applied but in a different direction,
- * where the source and destination will be swapped, and the source address will be replaced
- * with the internal address, which is obtained from the NAT mapping described above.
+ * where the source and destination will be swapped.
*/
-public abstract class NatPacketForwarderBase extends Thread {
- private static final String TAG = "NatPacketForwarder";
- static final int DESTINATION_PORT_OFFSET = 2;
+public class PacketForwarder extends Thread {
+ private static final String TAG = "PacketForwarder";
// The source fd to read packets from.
@NonNull
@@ -88,27 +69,12 @@
// The destination fd to write packets to.
@NonNull
final FileDescriptor mDstFd;
- // The NAT mapping table shared between two NatPacketForwarder instances to map from
- // the source port to the associated internal address. The map can be read/write from two
- // different threads on any given time whenever receiving packets on the
- // {@link TestNetworkInterface}. Thus, synchronize on the object when reading/writing is needed.
- @GuardedBy("mNatMap")
- @NonNull
- final PacketBridge.NatMap mNatMap;
- // The address of the external interface. See {@link NatPacketForwarder}.
- @NonNull
- final InetAddress mExtAddr;
/**
- * Construct a {@link NatPacketForwarderBase}.
+ * Construct a {@link PacketForwarder}.
*
* This class reads packets from {@code srcFd} of a {@link TestNetworkInterface}, and
- * forwards them to the {@code dstFd} of another {@link TestNetworkInterface} with
- * NAT applied. See {@link NatPacketForwarderBase}.
- *
- * To apply NAT, the address of the external interface needs to be supplied through
- * {@code extAddr} to identify the external interface. And a shared NAT mapping table,
- * {@code natMap} is needed to be shared between these two instances.
+ * forwards them to the {@code dstFd} of another {@link TestNetworkInterface}.
*
* Note that this class is not useful if the instance is not managed by a
* {@link PacketBridge} to set up a two-way communication.
@@ -116,29 +82,15 @@
* @param srcFd {@link FileDescriptor} to read packets from.
* @param mtu MTU of the test network.
* @param dstFd {@link FileDescriptor} to write packets to.
- * @param extAddr the external address, which is the address of the external interface.
- * See {@link NatPacketForwarderBase}.
- * @param natMap the NAT mapping table shared between two {@link NatPacketForwarderBase}
- * instance.
*/
- public NatPacketForwarderBase(@NonNull FileDescriptor srcFd, int mtu,
- @NonNull FileDescriptor dstFd, @NonNull InetAddress extAddr,
- @NonNull PacketBridge.NatMap natMap) {
+ public PacketForwarder(@NonNull FileDescriptor srcFd, int mtu,
+ @NonNull FileDescriptor dstFd) {
super(TAG);
mSrcFd = Objects.requireNonNull(srcFd);
mBuf = new byte[mtu];
mDstFd = Objects.requireNonNull(dstFd);
- mExtAddr = Objects.requireNonNull(extAddr);
- mNatMap = Objects.requireNonNull(natMap);
}
- /**
- * A method to prepare forwarding packets between two instances of {@link TestNetworkInterface},
- * which includes re-write addresses, ports and fix up checksums.
- * Subclasses should override this method to implement a simple NAT.
- */
- abstract void preparePacketForForwarding(@NonNull byte[] buf, int len, int version, int proto);
-
private void forwardPacket(@NonNull byte[] buf, int len) {
try {
Os.write(mDstFd, buf, 0, len);
@@ -190,8 +142,9 @@
if (len < ipHdrLen + transportHdrLen) {
throw new IllegalStateException("Unexpected buffer length: " + len);
}
- // Re-write addresses, ports and fix up checksums.
- preparePacketForForwarding(mBuf, len, version, proto);
+ // Swap addresses.
+ PacketReflectorUtil.swapAddresses(mBuf, version);
+
// Send the packet to the destination fd.
forwardPacket(mBuf, len);
}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/PacketReflector.java b/staticlibs/testutils/devicetests/com/android/testutils/PacketReflector.java
index 69392d4..ce20d67 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/PacketReflector.java
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketReflector.java
@@ -87,31 +87,6 @@
mBuf = new byte[mtu];
}
- private static void swapBytes(@NonNull byte[] buf, int pos1, int pos2, int len) {
- for (int i = 0; i < len; i++) {
- byte b = buf[pos1 + i];
- buf[pos1 + i] = buf[pos2 + i];
- buf[pos2 + i] = b;
- }
- }
-
- private static void swapAddresses(@NonNull byte[] buf, int version) {
- int addrPos, addrLen;
- switch (version) {
- case 4:
- addrPos = IPV4_ADDR_OFFSET;
- addrLen = IPV4_ADDR_LENGTH;
- break;
- case 6:
- addrPos = IPV6_ADDR_OFFSET;
- addrLen = IPV6_ADDR_LENGTH;
- break;
- default:
- throw new IllegalArgumentException();
- }
- swapBytes(buf, addrPos, addrPos + addrLen, addrLen);
- }
-
// Reflect TCP packets: swap the source and destination addresses, but don't change the ports.
// This is used by the test to "connect to itself" through the VPN.
private void processTcpPacket(@NonNull byte[] buf, int version, int len, int hdrLen) {
@@ -120,7 +95,7 @@
}
// Swap src and dst IP addresses.
- swapAddresses(buf, version);
+ PacketReflectorUtil.swapAddresses(buf, version);
// Send the packet back.
writePacket(buf, len);
@@ -134,11 +109,11 @@
}
// Swap src and dst IP addresses.
- swapAddresses(buf, version);
+ PacketReflectorUtil.swapAddresses(buf, version);
// Swap dst and src ports.
int portOffset = hdrLen;
- swapBytes(buf, portOffset, portOffset + 2, 2);
+ PacketReflectorUtil.swapBytes(buf, portOffset, portOffset + 2, 2);
// Send the packet back.
writePacket(buf, len);
@@ -160,7 +135,7 @@
// Swap src and dst IP addresses, and send the packet back.
// This effectively pings the device to see if it replies.
- swapAddresses(buf, version);
+ PacketReflectorUtil.swapAddresses(buf, version);
writePacket(buf, len);
// The device should have replied, and buf should now contain a ping response.
@@ -202,7 +177,7 @@
}
// Now swap the addresses again and reflect the packet. This sends a ping reply.
- swapAddresses(buf, version);
+ PacketReflectorUtil.swapAddresses(buf, version);
writePacket(buf, len);
}
diff --git a/staticlibs/testutils/devicetests/com/android/testutils/PacketReflectorUtil.kt b/staticlibs/testutils/devicetests/com/android/testutils/PacketReflectorUtil.kt
index 498b1a3..ad259c5 100644
--- a/staticlibs/testutils/devicetests/com/android/testutils/PacketReflectorUtil.kt
+++ b/staticlibs/testutils/devicetests/com/android/testutils/PacketReflectorUtil.kt
@@ -112,3 +112,28 @@
else -> throw IllegalArgumentException("Unsupported protocol: $protocol")
}
}
+
+fun swapBytes(buf: ByteArray, pos1: Int, pos2: Int, len: Int) {
+ for (i in 0 until len) {
+ val b = buf[pos1 + i]
+ buf[pos1 + i] = buf[pos2 + i]
+ buf[pos2 + i] = b
+ }
+}
+
+fun swapAddresses(buf: ByteArray, version: Int) {
+ val addrPos: Int
+ val addrLen: Int
+ when (version) {
+ 4 -> {
+ addrPos = PacketReflector.IPV4_ADDR_OFFSET
+ addrLen = PacketReflector.IPV4_ADDR_LENGTH
+ }
+ 6 -> {
+ addrPos = PacketReflector.IPV6_ADDR_OFFSET
+ addrLen = PacketReflector.IPV6_ADDR_LENGTH
+ }
+ else -> throw java.lang.IllegalArgumentException()
+ }
+ swapBytes(buf, addrPos, addrPos + addrLen, addrLen)
+}