Move ArpPacket.java to frameworks/libs/net

Bug: 281639507
Test: TH
Change-Id: Ic0d273695d3f0f85a0ec56337a9d12d77b60ea3b

1 files changed, 171 insertions, 0 deletions

diff --git a/common/device/com/android/net/module/util/arp/ArpPacket.java b/common/device/com/android/net/module/util/arp/ArpPacket.java
new file mode 100644
index 00000000..dab9694b
--- /dev/null
+++ b/common/device/com/android/net/module/util/arp/ArpPacket.java
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2019 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.net.module.util.arp;
+
+import static android.system.OsConstants.ETH_P_ARP;
+import static android.system.OsConstants.ETH_P_IP;
+
+import static com.android.net.module.util.NetworkStackConstants.ARP_ETHER_IPV4_LEN;
+import static com.android.net.module.util.NetworkStackConstants.ARP_HWTYPE_ETHER;
+import static com.android.net.module.util.NetworkStackConstants.ARP_REPLY;
+import static com.android.net.module.util.NetworkStackConstants.ARP_REQUEST;
+import static com.android.net.module.util.NetworkStackConstants.ETHER_ADDR_LEN;
+import static com.android.net.module.util.NetworkStackConstants.IPV4_ADDR_LEN;
+
+import android.net.MacAddress;
+
+import com.android.internal.annotations.VisibleForTesting;
+
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.BufferUnderflowException;
+import java.nio.ByteBuffer;
+
+/**
+ * Defines basic data and operations needed to build and parse packets for the
+ * ARP protocol.
+ *
+ * @hide
+ */
+public class ArpPacket {
+    private static final String TAG = "ArpPacket";
+
+    public final short opCode;
+    public final Inet4Address senderIp;
+    public final Inet4Address targetIp;
+    public final MacAddress senderHwAddress;
+    public final MacAddress targetHwAddress;
+
+    ArpPacket(short opCode, MacAddress senderHwAddress, Inet4Address senderIp,
+            MacAddress targetHwAddress, Inet4Address targetIp) {
+        this.opCode = opCode;
+        this.senderHwAddress = senderHwAddress;
+        this.senderIp = senderIp;
+        this.targetHwAddress = targetHwAddress;
+        this.targetIp = targetIp;
+    }
+
+    /**
+     * Build an ARP packet from the required specified parameters.
+     */
+    @VisibleForTesting
+    public static ByteBuffer buildArpPacket(final byte[] dstMac, final byte[] srcMac,
+            final byte[] targetIp, final byte[] targetHwAddress, byte[] senderIp,
+            final short opCode) {
+        final ByteBuffer buf = ByteBuffer.allocate(ARP_ETHER_IPV4_LEN);
+
+        // Ether header
+        buf.put(dstMac);
+        buf.put(srcMac);
+        buf.putShort((short) ETH_P_ARP);
+
+        // ARP header
+        buf.putShort((short) ARP_HWTYPE_ETHER);  // hrd
+        buf.putShort((short) ETH_P_IP);          // pro
+        buf.put((byte) ETHER_ADDR_LEN);          // hln
+        buf.put((byte) IPV4_ADDR_LEN);           // pln
+        buf.putShort(opCode);                    // op
+        buf.put(srcMac);                         // sha
+        buf.put(senderIp);                       // spa
+        buf.put(targetHwAddress);                // tha
+        buf.put(targetIp);                       // tpa
+        buf.flip();
+        return buf;
+    }
+
+    /**
+     * Parse an ARP packet from a ByteBuffer object.
+     */
+    @VisibleForTesting
+    public static ArpPacket parseArpPacket(final byte[] recvbuf, final int length)
+            throws ParseException {
+        try {
+            if (length < ARP_ETHER_IPV4_LEN || recvbuf.length < length) {
+                throw new ParseException("Invalid packet length: " + length);
+            }
+
+            final ByteBuffer buffer = ByteBuffer.wrap(recvbuf, 0, length);
+            byte[] l2dst = new byte[ETHER_ADDR_LEN];
+            byte[] l2src = new byte[ETHER_ADDR_LEN];
+            buffer.get(l2dst);
+            buffer.get(l2src);
+
+            final short etherType = buffer.getShort();
+            if (etherType != ETH_P_ARP) {
+                throw new ParseException("Incorrect Ether Type: " + etherType);
+            }
+
+            final short hwType = buffer.getShort();
+            if (hwType != ARP_HWTYPE_ETHER) {
+                throw new ParseException("Incorrect HW Type: " + hwType);
+            }
+
+            final short protoType = buffer.getShort();
+            if (protoType != ETH_P_IP) {
+                throw new ParseException("Incorrect Protocol Type: " + protoType);
+            }
+
+            final byte hwAddrLength = buffer.get();
+            if (hwAddrLength != ETHER_ADDR_LEN) {
+                throw new ParseException("Incorrect HW address length: " + hwAddrLength);
+            }
+
+            final byte ipAddrLength = buffer.get();
+            if (ipAddrLength != IPV4_ADDR_LEN) {
+                throw new ParseException("Incorrect Protocol address length: " + ipAddrLength);
+            }
+
+            final short opCode = buffer.getShort();
+            if (opCode != ARP_REQUEST && opCode != ARP_REPLY) {
+                throw new ParseException("Incorrect opCode: " + opCode);
+            }
+
+            byte[] senderHwAddress = new byte[ETHER_ADDR_LEN];
+            byte[] senderIp = new byte[IPV4_ADDR_LEN];
+            buffer.get(senderHwAddress);
+            buffer.get(senderIp);
+
+            byte[] targetHwAddress = new byte[ETHER_ADDR_LEN];
+            byte[] targetIp = new byte[IPV4_ADDR_LEN];
+            buffer.get(targetHwAddress);
+            buffer.get(targetIp);
+
+            return new ArpPacket(opCode, MacAddress.fromBytes(senderHwAddress),
+                    (Inet4Address) InetAddress.getByAddress(senderIp),
+                    MacAddress.fromBytes(targetHwAddress),
+                    (Inet4Address) InetAddress.getByAddress(targetIp));
+        } catch (IndexOutOfBoundsException e) {
+            throw new ParseException("Invalid index when wrapping a byte array into a buffer");
+        } catch (BufferUnderflowException e) {
+            throw new ParseException("Invalid buffer position");
+        } catch (IllegalArgumentException e) {
+            throw new ParseException("Invalid MAC address representation");
+        } catch (UnknownHostException e) {
+            throw new ParseException("Invalid IP address of Host");
+        }
+    }
+
+    /**
+     * Thrown when parsing ARP packet failed.
+     */
+    public static class ParseException extends Exception {
+        ParseException(String message) {
+            super(message);
+        }
+    }
+}