Add prefixmsg struct to parse RTM_NEWPREFIX message header.

Bug: 315069348
Test: TH
Change-Id: I8bc5bee20f3043203f591bdfe31a4879a09d1565

1 files changed, 94 insertions, 0 deletions

diff --git a/staticlibs/device/com/android/net/module/util/netlink/StructPrefixMsg.java b/staticlibs/device/com/android/net/module/util/netlink/StructPrefixMsg.java
new file mode 100644
index 0000000000..504d6c79b3
--- /dev/null
+++ b/staticlibs/device/com/android/net/module/util/netlink/StructPrefixMsg.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2024 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.netlink;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+
+import com.android.net.module.util.Struct;
+import com.android.net.module.util.Struct.Field;
+import com.android.net.module.util.Struct.Type;
+
+import java.nio.ByteBuffer;
+
+/**
+ * struct prefixmsg {
+ *     unsigned char  prefix_family;
+ *     unsigned char  prefix_pad1;
+ *     unsigned short prefix_pad2;
+ *     int            prefix_ifindex;
+ *     unsigned char  prefix_type;
+ *     unsigned char  prefix_len;
+ *     unsigned char  prefix_flags;
+ *     unsigned char  prefix_pad3;
+ * }
+ *
+ * see also:
+ *
+ *     include/uapi/linux/rtnetlink.h
+ *
+ * @hide
+ */
+public class StructPrefixMsg extends Struct {
+    // Already aligned.
+    public static final int STRUCT_SIZE = 12;
+
+    @Field(order = 0, type = Type.U8, padding = 3)
+    public final short prefix_family;
+    @Field(order = 1, type = Type.S32)
+    public final int prefix_ifindex;
+    @Field(order = 2, type = Type.U8)
+    public final short prefix_type;
+    @Field(order = 3, type = Type.U8)
+    public final short prefix_len;
+    @Field(order = 4, type = Type.U8, padding = 1)
+    public final short prefix_flags;
+
+    @VisibleForTesting
+    public StructPrefixMsg(short family, int ifindex, short type, short len, short flags) {
+        this.prefix_family = family;
+        this.prefix_ifindex = ifindex;
+        this.prefix_type = type;
+        this.prefix_len = len;
+        this.prefix_flags = flags;
+    }
+
+    /**
+     * Parse a prefixmsg struct from a {@link ByteBuffer}.
+     *
+     * @param byteBuffer The buffer from which to parse the prefixmsg.
+     * @return the parsed prefixmsg struct, or throw IllegalArgumentException if the prefixmsg
+     *         struct could not be parsed successfully (for example, if it was truncated).
+     */
+    public static StructPrefixMsg parse(@NonNull final ByteBuffer byteBuffer) {
+        if (byteBuffer.remaining() < STRUCT_SIZE) {
+            throw new IllegalArgumentException("Invalid bytebuffer remaining size "
+                    + byteBuffer.remaining() + "for prefix_msg struct.");
+        }
+
+        // The ByteOrder must already have been set to native order.
+        return Struct.parse(StructPrefixMsg.class, byteBuffer);
+    }
+
+    /**
+     * Write a prefixmsg struct to {@link ByteBuffer}.
+     */
+    public void pack(@NonNull final ByteBuffer byteBuffer) {
+        // The ByteOrder must already have been set to native order.
+        writeToByteBuffer(byteBuffer);
+    }
+}