1 files changed, 121 insertions, 0 deletions
diff --git a/common/netlinkclient/src/android/net/netlink/StructNdOptPref64.java b/common/netlinkclient/src/android/net/netlink/StructNdOptPref64.java
new file mode 100644
index 0000000..6a68df8
--- /dev/null
+++ b/common/netlinkclient/src/android/net/netlink/StructNdOptPref64.java
@@ -0,0 +1,121 @@
+/*
+ * 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 android.net.netlink;
+
+import android.net.IpPrefix;
+import android.util.Log;
+
+import androidx.annotation.NonNull;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+import java.nio.ByteBuffer;
+
+/**
+ * The PREF64 router advertisement option. RFC 8781.
+ *
+ * 0                   1                   2                   3
+ * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |     Type      |    Length     |     Scaled Lifetime     | PLC |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ * |                                                               |
+ * +                                                               +
+ * |              Highest 96 bits of the Prefix                    |
+ * +                                                               +
+ * |                                                               |
+ * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ */
+public class StructNdOptPref64 {
+    public static final int STRUCT_SIZE = 16;
+    public static final int TYPE = 38;
+
+    private static final String TAG = StructNdOptPref64.class.getSimpleName();
+
+    /** The option type. Always ICMPV6_ND_OPTION_PREF64. */
+    public final byte type;
+    /** The length of the option in 8-byte units. Actually an unsigned 8-bit integer. */
+    public final int length;
+    /**
+     * How many seconds the prefix is expected to remain valid.
+     * Valid values are from 0 to 65528 in multiples of 8.
+     */
+    public final int lifetime;
+    /** The NAT64 prefix. */
+    public final IpPrefix prefix;
+
+    int plcToPrefixLength(int plc) {
+        switch (plc) {
+            case 0: return 96;
+            case 1: return 64;
+            case 2: return 56;
+            case 3: return 48;
+            case 4: return 40;
+            case 5: return 32;
+            default:
+                throw new IllegalArgumentException("Invalid prefix length code " + plc);
+        }
+    }
+
+    StructNdOptPref64(@NonNull ByteBuffer buf) {
+        type = buf.get();
+        length = buf.get();
+        if (type != TYPE) throw new IllegalArgumentException("Invalid type " + type);
+        if (length != 2) throw new IllegalArgumentException("Invalid length " + length);
+
+        int scaledLifetimePlc = Short.toUnsignedInt(buf.getShort());
+        lifetime = scaledLifetimePlc & 0xfff8;
+
+        byte[] addressBytes = new byte[16];
+        buf.get(addressBytes, 0, 12);
+        InetAddress addr;
+        try {
+            addr = InetAddress.getByAddress(addressBytes);
+        } catch (UnknownHostException e) {
+            throw new AssertionError("16-byte array not valid InetAddress?");
+        }
+        prefix = new IpPrefix(addr, plcToPrefixLength(scaledLifetimePlc & 7));
+    }
+
+    /**
+     * Parses an option from a {@link ByteBuffer}.
+     *
+     * @param buf The buffer from which to parse the option. The buffer's byte order must be
+     *            {@link java.nio.ByteOrder#BIG_ENDIAN}.
+     * @return the parsed option, or {@code null} if the option could not be parsed successfully
+     *         (for example, if it was truncated, or if the prefix length code was wrong).
+     */
+    public static StructNdOptPref64 parse(@NonNull ByteBuffer buf) {
+        if (buf == null || buf.remaining() < STRUCT_SIZE) return null;
+        try {
+            return new StructNdOptPref64(buf);
+        } catch (IllegalArgumentException e) {
+            // Not great, but better than throwing an exception that might crash the caller.
+            // Convention in this package is that null indicates that the option was truncated, so
+            // callers must already handle it.
+            Log.d(TAG, "Invalid PREF64 option: " + e);
+            return null;
+        }
+    }
+
+    @Override
+    @NonNull
+    public String toString() {
+        return String.format("NdOptPref64(%s, %d)", prefix, lifetime);
+    }
+}