Use netlink to set interface up/down in EthernetTracker(1/2)
Currently EthernetTracker uses netd to interact with interfaces, such as
retrieving all interfaces, updating interface configurations etc.
However, the usage of netd can bring some unexpected side effects, such
as clearing v4 address when toggling on/off interface.
This change moves forward with one less usage of netd to use netlink
directly to set interface up/down in EthernetTracker.
This patch adds support in netlink utils to get/set interface flags and
added related unit test.
Bug: 379021505
Test: atest NetworkStaticLibTests
Change-Id: I5f82781663ba340588450cceea55caec4e3991a8
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..e2544d3 100644
--- a/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java
+++ b/staticlibs/device/com/android/net/module/util/netlink/NetlinkUtils.java
@@ -55,6 +55,7 @@
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
+import java.util.Arrays;
import java.util.List;
import java.util.Objects;
import java.util.function.Consumer;
@@ -469,4 +470,31 @@
// Nothing we can do here
}
}
+
+ /**
+ * Sends a netlink request to set flags for given interface
+ *
+ * @param interfaceName The name of the network interface to query.
+ * @param flags power-of-two integer flags to set or unset. A flag to set should be passed as
+ * is as a power-of-two value, and a flag to remove should be passed inversed as -1 with
+ * a single bit down. For example: IFF_UP, ~IFF_BROADCAST...
+ * @return true if the request finished successfully, otherwise false.
+ */
+ public static boolean setInterfaceFlags(@NonNull String interfaceName, int... flags) {
+ final RtNetlinkLinkMessage ntMsg =
+ RtNetlinkLinkMessage.createSetFlagsMessage(interfaceName, /*seqNo*/ 0, flags);
+ if (ntMsg == null) {
+ Log.e(TAG, "Failed to create message to set interface flags for interface "
+ + interfaceName + ", input flags are: " + Arrays.toString(flags));
+ return false;
+ }
+ final byte[] msg = ntMsg.pack(ByteOrder.nativeOrder());
+ try {
+ NetlinkUtils.sendOneShotKernelMessage(NETLINK_ROUTE, msg);
+ return true;
+ } catch (ErrnoException e) {
+ Log.e(TAG, "Failed to set flags for: " + interfaceName, e);
+ return false;
+ }
+ }
}
diff --git a/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java b/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
index 037d95f..1afe3b8 100644
--- a/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
+++ b/staticlibs/device/com/android/net/module/util/netlink/RtNetlinkLinkMessage.java
@@ -312,6 +312,57 @@
DEFAULT_MTU, null, null);
}
+ /**
+ * Creates an {@link RtNetlinkLinkMessage} instance that can be used to set the flags of a
+ * network interface.
+ *
+ * @param interfaceName The name of the network interface to query.
+ * @param sequenceNumber The sequence number for the Netlink message.
+ * @param flags power-of-two integer flags to set or unset. A flag to set should be passed as
+ * is as a power-of-two value, and a flag to remove should be passed inversed as -1 with
+ * a single bit down. For example: IFF_UP, ~IFF_BROADCAST...
+ * @return An `RtNetlinkLinkMessage` instance representing the request to query the interface.
+ */
+ @Nullable
+ public static RtNetlinkLinkMessage createSetFlagsMessage(@NonNull String interfaceName,
+ int sequenceNumber, int... flags) {
+ return createSetFlagsMessage(
+ interfaceName, sequenceNumber, new OsAccess(), flags);
+ }
+
+ @VisibleForTesting
+ @Nullable
+ protected static RtNetlinkLinkMessage createSetFlagsMessage(
+ @NonNull String interfaceName, int sequenceNumber, @NonNull OsAccess osAccess,
+ int... flags) {
+ final int interfaceIndex = osAccess.if_nametoindex(interfaceName);
+ if (interfaceIndex == OsAccess.INVALID_INTERFACE_INDEX) {
+ return null;
+ }
+
+ int flagsBits = 0;
+ int changeBits = 0;
+ for (int f : flags) {
+ if (Integer.bitCount(f) == 1) {
+ flagsBits |= f;
+ changeBits |= f;
+ } else if (Integer.bitCount(~f) == 1) {
+ flagsBits &= f;
+ changeBits |= ~f;
+ } else {
+ return null;
+ }
+ }
+ // RTM_NEWLINK is used here for create, modify, or notify changes about a internet
+ // interface, including change in administrative state. While RTM_SETLINK is used to
+ // modify an existing link rather than creating a new one.
+ return RtNetlinkLinkMessage.build(
+ new StructNlMsgHdr(/*payloadLen*/ 0, RTM_NEWLINK, NLM_F_REQUEST, sequenceNumber),
+ new StructIfinfoMsg((short) AF_UNSPEC, /*type*/ 0, interfaceIndex,
+ flagsBits, changeBits),
+ DEFAULT_MTU, /*hardwareAddress*/ null, /*interfaceName*/ null);
+ }
+
@Override
public String toString() {
return "RtNetlinkLinkMessage{ "
diff --git a/staticlibs/tests/unit/src/com/android/net/module/util/netlink/RtNetlinkLinkMessageTest.java b/staticlibs/tests/unit/src/com/android/net/module/util/netlink/RtNetlinkLinkMessageTest.java
index bd0e31d..8104e3a 100644
--- a/staticlibs/tests/unit/src/com/android/net/module/util/netlink/RtNetlinkLinkMessageTest.java
+++ b/staticlibs/tests/unit/src/com/android/net/module/util/netlink/RtNetlinkLinkMessageTest.java
@@ -306,6 +306,28 @@
}
@Test
+ public void testCreateSetInterfaceFlagsMessage() {
+ final String expectedHexBytes =
+ "20000000100001006824000000000000" // struct nlmsghdr
+ + "00000000080000000100000001000100"; // struct ifinfomsg
+ final String interfaceName = "wlan0";
+ final int interfaceIndex = 8;
+ final int sequenceNumber = 0x2468;
+
+ when(mOsAccess.if_nametoindex(interfaceName)).thenReturn(interfaceIndex);
+
+ final RtNetlinkLinkMessage msg = RtNetlinkLinkMessage.createSetFlagsMessage(
+ interfaceName,
+ sequenceNumber,
+ mOsAccess,
+ NetlinkConstants.IFF_UP,
+ ~NetlinkConstants.IFF_LOWER_UP);
+ assertNotNull(msg);
+ final byte[] bytes = msg.pack(ByteOrder.LITTLE_ENDIAN); // For testing.
+ assertEquals(expectedHexBytes, HexDump.toHexString(bytes));
+ }
+
+ @Test
public void testToString() {
final ByteBuffer byteBuffer = toByteBuffer(RTM_NEWLINK_HEX);
byteBuffer.order(ByteOrder.LITTLE_ENDIAN); // For testing.