Merge "Add link-related methods at NetlinkUtils" into main
diff --git a/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java b/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java
index 541a375..f34159e 100644
--- a/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java
+++ b/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java
@@ -30,6 +30,7 @@
 import static android.system.OsConstants.SO_RCVTIMEO;
 import static android.system.OsConstants.SO_SNDTIMEO;
 
+import static com.android.net.module.util.netlink.NetlinkConstants.RTM_NEWLINK;
 import static com.android.net.module.util.netlink.NetlinkConstants.hexify;
 import static com.android.net.module.util.netlink.NetlinkConstants.NLMSG_DONE;
 import static com.android.net.module.util.netlink.NetlinkConstants.RTNL_FAMILY_IP6MR;
@@ -57,6 +58,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.Consumer;
 
 /**
@@ -225,6 +227,96 @@
     }
 
     /**
+     * Sends an RTM_NEWLINK message to kernel to set a network interface up or down.
+     *
+     * @param ifName  The name of the network interface to modify.
+     * @param isUp    {@code true} to set the interface up, {@code false} to set it down.
+     * @return {@code true} if the request was successfully sent, {@code false} otherwise.
+     */
+    public static boolean sendRtmSetLinkStateRequest(@NonNull String ifName, boolean isUp) {
+        final RtNetlinkLinkMessage msg = RtNetlinkLinkMessage.createSetLinkStateMessage(
+                ifName, 1 /*sequenceNumber*/, isUp);
+        if (msg == null) {
+            return false;
+        }
+
+        final byte[] bytes = msg.pack(ByteOrder.nativeOrder());
+        try {
+            NetlinkUtils.sendOneShotKernelMessage(NETLINK_ROUTE, bytes);
+            return true;
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Fail to set the interface " + ifName + " " + (isUp ? "up" : "down"), e);
+            return false;
+        }
+    }
+
+    /**
+     * Sends an RTM_NEWLINK message to kernel to rename a network interface.
+     *
+     * @param ifName     The current name of the network interface.
+     * @param newIfName  The new name to assign to the interface.
+     * @return {@code true} if the request was successfully sent, {@code false} otherwise.
+     */
+    public static boolean sendRtmSetLinkNameRequest(
+            @NonNull String ifName, @NonNull String newIfName) {
+        final RtNetlinkLinkMessage msg = RtNetlinkLinkMessage.createSetLinkNameMessage(
+                ifName, 1 /*sequenceNumber*/, newIfName);
+        if (msg == null) {
+            return false;
+        }
+
+        final byte[] bytes = msg.pack(ByteOrder.nativeOrder());
+        try {
+            NetlinkUtils.sendOneShotKernelMessage(NETLINK_ROUTE, bytes);
+            return true;
+        } catch (ErrnoException e) {
+            Log.e(TAG, "Fail to rename the interface from " + ifName + " to " + newIfName, e);
+            return false;
+        }
+    }
+
+    /**
+     * Gets the information of a network interface using a Netlink message.
+     * <p>
+     * This method sends a Netlink message to the kernel to request information about the specified
+     * network interface and returns a {@link RtNetlinkLinkMessage} containing the interface status.
+     *
+     * @param ifName The name of the network interface to query.
+     * @return An {@link RtNetlinkLinkMessage} containing the interface status, or {@code null} if
+     *         the interface does not exist or an error occurred during the query.
+     */
+    @Nullable
+    public static RtNetlinkLinkMessage getLinkRequest(@NonNull String ifName) {
+        final int ifIndex = new OsAccess().if_nametoindex(ifName);
+        if (ifIndex == OsAccess.INVALID_INTERFACE_INDEX) {
+            return null;
+        }
+
+        final AtomicReference<RtNetlinkLinkMessage> recvMsg = new AtomicReference<>();
+        final Consumer<RtNetlinkLinkMessage> handleNlMsg = (msg) -> {
+            if (msg.getHeader().nlmsg_type == RTM_NEWLINK
+                    && msg.getIfinfoHeader().index == ifIndex) {
+                recvMsg.set(msg);
+            }
+        };
+
+        final RtNetlinkLinkMessage msg = RtNetlinkLinkMessage.createGetLinkMessage(
+                ifName, 1 /*sequenceNumber*/);
+        if (msg == null) {
+            return null;
+        }
+
+        final byte[] bytes = msg.pack(ByteOrder.nativeOrder());
+        try {
+            NetlinkUtils.getAndProcessNetlinkDumpMessages(
+                    bytes, NETLINK_ROUTE, RtNetlinkLinkMessage.class, handleNlMsg);
+        } catch (SocketException | InterruptedIOException | ErrnoException e) {
+            // Nothing we can do here.
+        }
+        return recvMsg.get();
+    }
+
+    /**
      * Create netlink socket with the given netlink protocol type and buffersize.
      *
      * @param nlProto the netlink protocol