Accept DHCP responses from non-67 server source ports (b19238c4) · Commits · e / os / android_frameworks_base

services/net/java/android/net/dhcp/DhcpPacket.java

+14 −2

Original line number	Diff line number	Diff line
		@@ -673,6 +673,14 @@ abstract class DhcpPacket {
		return new String(bytes, 0, length, StandardCharsets.US_ASCII);
		}

		private static boolean isPacketToOrFromClient(short udpSrcPort, short udpDstPort) {
		return (udpSrcPort == DHCP_CLIENT) \|\| (udpDstPort == DHCP_CLIENT);
		}

		private static boolean isPacketServerToServer(short udpSrcPort, short udpDstPort) {
		return (udpSrcPort == DHCP_SERVER) && (udpDstPort == DHCP_SERVER);
		}

		public static class ParseException extends Exception {
		public ParseException(String msg, Object... args) {
		super(String.format(msg, args));
		@@ -791,8 +799,12 @@ abstract class DhcpPacket {
		short udpLen = packet.getShort();
		short udpChkSum = packet.getShort();

		if ((udpSrcPort != DHCP_SERVER) && (udpSrcPort != DHCP_CLIENT)) {
		throw new ParseException("Invalid source port %d", udpSrcPort);
		// Only accept packets to or from the well-known client port (expressly permitting
		// packets from ports other than the well-known server port; http://b/24687559), and
		// server-to-server packets, e.g. for relays.
		if (!isPacketToOrFromClient(udpSrcPort, udpDstPort) &&
		!isPacketServerToServer(udpSrcPort, udpDstPort)) {
		return null;
		}
		}

services/tests/servicestests/src/android/net/dhcp/DhcpPacketTest.java

+36 −0

Original line number	Diff line number	Diff line
		@@ -514,4 +514,40 @@ public class DhcpPacketTest extends TestCase {
		assertDhcpResults("10.32.158.205/20", "10.32.144.1", "148.88.65.52,148.88.65.53",
		"lancs.ac.uk", "10.32.255.128", null, 7200, false, dhcpResults);
		}

		@SmallTest
		public void testUdpServerAnySourcePort() throws Exception {
		final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
		// Ethernet header.
		"9cd917000000001c2e0000000800" +
		// IP header.
		"45a00148000040003d115087d18194fb0a0f7af2" +
		// UDP header. TODO: fix invalid checksum (due to MAC address obfuscation).
		// NOTE: The server source port is not the canonical port 67.
		"C29F004401341268" +
		// BOOTP header.
		"02010600d628ba8200000000000000000a0f7af2000000000a0fc818" +
		// MAC address.
		"9cd91700000000000000000000000000" +
		// Server name.
		"0000000000000000000000000000000000000000000000000000000000000000" +
		"0000000000000000000000000000000000000000000000000000000000000000" +
		// File.
		"0000000000000000000000000000000000000000000000000000000000000000" +
		"0000000000000000000000000000000000000000000000000000000000000000" +
		"0000000000000000000000000000000000000000000000000000000000000000" +
		"0000000000000000000000000000000000000000000000000000000000000000" +
		// Options.
		"6382536335010236040a0169fc3304000151800104ffff000003040a0fc817060cd1818003d1819403" +
		"d18180060f0777766d2e6564751c040a0fffffff000000"
		).toCharArray(), false));

		DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
		assertTrue(offerPacket instanceof DhcpOfferPacket);
		assertEquals("9CD917000000", HexDump.toHexString(offerPacket.getClientMac()));
		DhcpResults dhcpResults = offerPacket.toDhcpResults();
		assertDhcpResults("10.15.122.242/16", "10.15.200.23",
		"209.129.128.3,209.129.148.3,209.129.128.6",
		"wvm.edu", "10.1.105.252", null, 86400, false, dhcpResults);
		}
		}