Catch runtime exceptions when parsing DHCP packets
This patch adds a try catch all to DHCP packet parsing so that
DhcpClient does not choke on malformed packets, brinding down with it
the whole framework.
Test: added new unit tests catching the issue fixed in this patch.
Bug: 31850211
Change-Id: I3c50a149fed6b2cbc4f40bb4f0e5bb2b56859b44
diff --git a/core/java/android/net/metrics/DhcpErrorEvent.java b/core/java/android/net/metrics/DhcpErrorEvent.java
index 59c5fb6..1972b9e 100644
--- a/core/java/android/net/metrics/DhcpErrorEvent.java
+++ b/core/java/android/net/metrics/DhcpErrorEvent.java
@@ -53,6 +53,8 @@
public static final int BUFFER_UNDERFLOW = makeErrorCode(MISC_ERROR, 1);
public static final int RECEIVE_ERROR = makeErrorCode(MISC_ERROR, 2);
+ /** {@hide} */
+ public static final int PARSING_ERROR = makeErrorCode(MISC_ERROR, 3);
public final String ifName;
// error code byte format (MSB to LSB):
@@ -115,8 +117,9 @@
}
final static class Decoder {
- static final SparseArray<String> constants =
- MessageUtils.findMessageNames(new Class[]{DhcpErrorEvent.class},
- new String[]{"L2_", "L3_", "L4_", "BOOTP_", "DHCP_", "BUFFER_", "RECEIVE_"});
+ static final SparseArray<String> constants = MessageUtils.findMessageNames(
+ new Class[]{DhcpErrorEvent.class},
+ new String[]{"L2_", "L3_", "L4_", "BOOTP_", "DHCP_", "BUFFER_", "RECEIVE_",
+ "PARSING_"});
}
}
diff --git a/services/net/java/android/net/dhcp/DhcpPacket.java b/services/net/java/android/net/dhcp/DhcpPacket.java
index 9aa66fe..fc7cf2e 100644
--- a/services/net/java/android/net/dhcp/DhcpPacket.java
+++ b/services/net/java/android/net/dhcp/DhcpPacket.java
@@ -7,6 +7,7 @@
import android.os.Build;
import android.os.SystemProperties;
import android.system.OsConstants;
+import com.android.internal.annotations.VisibleForTesting;
import java.io.UnsupportedEncodingException;
import java.net.Inet4Address;
@@ -14,9 +15,8 @@
import java.nio.BufferUnderflowException;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
-import java.nio.charset.StandardCharsets;
import java.nio.ShortBuffer;
-
+import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
@@ -725,7 +725,8 @@
* A subset of the optional parameters are parsed and are stored
* in object fields.
*/
- public static DhcpPacket decodeFullPacket(ByteBuffer packet, int pktType) throws ParseException
+ @VisibleForTesting
+ static DhcpPacket decodeFullPacket(ByteBuffer packet, int pktType) throws ParseException
{
// bootp parameters
int transactionId;
@@ -1090,7 +1091,13 @@
public static DhcpPacket decodeFullPacket(byte[] packet, int length, int pktType)
throws ParseException {
ByteBuffer buffer = ByteBuffer.wrap(packet, 0, length).order(ByteOrder.BIG_ENDIAN);
- return decodeFullPacket(buffer, pktType);
+ try {
+ return decodeFullPacket(buffer, pktType);
+ } catch (ParseException e) {
+ throw e;
+ } catch (Exception e) {
+ throw new ParseException(DhcpErrorEvent.PARSING_ERROR, e.getMessage());
+ }
}
/**
diff --git a/services/tests/servicestests/src/android/net/dhcp/DhcpPacketTest.java b/services/tests/servicestests/src/android/net/dhcp/DhcpPacketTest.java
index f8eaf7d..b4e9db77 100644
--- a/services/tests/servicestests/src/android/net/dhcp/DhcpPacketTest.java
+++ b/services/tests/servicestests/src/android/net/dhcp/DhcpPacketTest.java
@@ -16,24 +16,21 @@
package android.net.dhcp;
-import android.net.NetworkUtils;
import android.net.DhcpResults;
import android.net.LinkAddress;
+import android.net.NetworkUtils;
+import android.net.metrics.DhcpErrorEvent;
import android.system.OsConstants;
import android.test.suitebuilder.annotation.SmallTest;
import com.android.internal.util.HexDump;
-
import java.net.Inet4Address;
import java.nio.ByteBuffer;
import java.util.ArrayList;
-
-import junit.framework.TestCase;
-import libcore.util.HexEncoding;
import java.util.Arrays;
+import junit.framework.TestCase;
import static android.net.dhcp.DhcpPacket.*;
-
public class DhcpPacketTest extends TestCase {
private static Inet4Address SERVER_ADDR = v4Address("192.0.2.1");
@@ -285,7 +282,7 @@
// TODO: Turn all of these into golden files. This will probably require modifying
// Android.mk appropriately, making this into an AndroidTestCase, and adding code to read
// the golden files from the test APK's assets via mContext.getAssets().
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// IP header.
"451001480000000080118849c0a89003c0a89ff7" +
// UDP header.
@@ -304,8 +301,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options
"638253633501023604c0a89003330400001c200104fffff0000304c0a89ffe06080808080808080404" +
- "3a0400000e103b040000189cff00000000000000000000"
- ).toCharArray(), false));
+ "3a0400000e103b040000189cff00000000000000000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L3);
assertTrue(offerPacket instanceof DhcpOfferPacket); // Implicitly checks it's non-null.
@@ -316,7 +312,7 @@
@SmallTest
public void testOffer2() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// IP header.
"450001518d0600004011144dc0a82b01c0a82bf7" +
// UDP header.
@@ -335,8 +331,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options
"638253633501023604c0a82b01330400000e103a04000007083b0400000c4e0104ffffff00" +
- "1c04c0a82bff0304c0a82b010604c0a82b012b0f414e44524f49445f4d455445524544ff"
- ).toCharArray(), false));
+ "1c04c0a82bff0304c0a82b010604c0a82b012b0f414e44524f49445f4d455445524544ff"));
assertEquals(337, packet.limit());
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L3);
@@ -347,6 +342,136 @@
assertTrue(dhcpResults.hasMeteredHint());
}
+ @SmallTest
+ public void testBadIpPacket() throws Exception {
+ final byte[] packet = HexDump.hexStringToByteArray(
+ // IP header.
+ "450001518d0600004011144dc0a82b01c0a82bf7");
+
+ try {
+ DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, packet.length, ENCAP_L3);
+ } catch (DhcpPacket.ParseException expected) {
+ assertDhcpErrorCodes(DhcpErrorEvent.L3_TOO_SHORT, expected.errorCode);
+ return;
+ }
+ fail("Dhcp packet parsing should have failed");
+ }
+
+ @SmallTest
+ public void testBadDhcpPacket() throws Exception {
+ final byte[] packet = HexDump.hexStringToByteArray(
+ // IP header.
+ "450001518d0600004011144dc0a82b01c0a82bf7" +
+ // UDP header.
+ "00430044013d9ac7" +
+ // BOOTP header.
+ "02010600dfc23d1f0002000000000000c0a82bf7c0a82b0100000000");
+
+ try {
+ DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, packet.length, ENCAP_L3);
+ } catch (DhcpPacket.ParseException expected) {
+ assertDhcpErrorCodes(DhcpErrorEvent.L3_TOO_SHORT, expected.errorCode);
+ return;
+ }
+ fail("Dhcp packet parsing should have failed");
+ }
+
+ @SmallTest
+ public void testBadTruncatedOffer() throws Exception {
+ final byte[] packet = HexDump.hexStringToByteArray(
+ // IP header.
+ "450001518d0600004011144dc0a82b01c0a82bf7" +
+ // UDP header.
+ "00430044013d9ac7" +
+ // BOOTP header.
+ "02010600dfc23d1f0002000000000000c0a82bf7c0a82b0100000000" +
+ // MAC address.
+ "30766ff2a90c00000000000000000000" +
+ // Server name.
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ // File, missing one byte
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "00000000000000000000000000000000000000000000000000000000000000");
+
+ try {
+ DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, packet.length, ENCAP_L3);
+ } catch (DhcpPacket.ParseException expected) {
+ assertDhcpErrorCodes(DhcpErrorEvent.L3_TOO_SHORT, expected.errorCode);
+ return;
+ }
+ fail("Dhcp packet parsing should have failed");
+ }
+
+ @SmallTest
+ public void testBadOfferWithoutACookie() throws Exception {
+ final byte[] packet = HexDump.hexStringToByteArray(
+ // IP header.
+ "450001518d0600004011144dc0a82b01c0a82bf7" +
+ // UDP header.
+ "00430044013d9ac7" +
+ // BOOTP header.
+ "02010600dfc23d1f0002000000000000c0a82bf7c0a82b0100000000" +
+ // MAC address.
+ "30766ff2a90c00000000000000000000" +
+ // Server name.
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ // File.
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000"
+ // No options
+ );
+
+ try {
+ DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, packet.length, ENCAP_L3);
+ } catch (DhcpPacket.ParseException expected) {
+ assertDhcpErrorCodes(DhcpErrorEvent.PARSING_ERROR, expected.errorCode);
+ return;
+ }
+ fail("Dhcp packet parsing should have failed");
+ }
+
+ @SmallTest
+ public void testOfferWithBadCookie() throws Exception {
+ final byte[] packet = HexDump.hexStringToByteArray(
+ // IP header.
+ "450001518d0600004011144dc0a82b01c0a82bf7" +
+ // UDP header.
+ "00430044013d9ac7" +
+ // BOOTP header.
+ "02010600dfc23d1f0002000000000000c0a82bf7c0a82b0100000000" +
+ // MAC address.
+ "30766ff2a90c00000000000000000000" +
+ // Server name.
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ // File.
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ "0000000000000000000000000000000000000000000000000000000000000000" +
+ // Bad cookie
+ "DEADBEEF3501023604c0a82b01330400000e103a04000007083b0400000c4e0104ffffff00" +
+ "1c04c0a82bff0304c0a82b010604c0a82b012b0f414e44524f49445f4d455445524544ff");
+
+ try {
+ DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, packet.length, ENCAP_L3);
+ } catch (DhcpPacket.ParseException expected) {
+ assertDhcpErrorCodes(DhcpErrorEvent.DHCP_BAD_MAGIC_COOKIE, expected.errorCode);
+ return;
+ }
+ fail("Dhcp packet parsing should have failed");
+ }
+
+ private void assertDhcpErrorCodes(int expected, int got) {
+ assertEquals(Integer.toHexString(expected), Integer.toHexString(got));
+ }
+
private byte[] mtuBytes(int mtu) {
// 0x1a02: option 26, length 2. 0xff: no more options.
if (mtu > Short.MAX_VALUE - Short.MIN_VALUE) {
@@ -354,7 +479,7 @@
String.format("Invalid MTU %d, must be 16-bit unsigned", mtu));
}
String hexString = String.format("1a02%04xff", mtu);
- return HexEncoding.decode(hexString.toCharArray(), false);
+ return HexDump.hexStringToByteArray(hexString);
}
private void checkMtu(ByteBuffer packet, int expectedMtu, byte[] mtuBytes) throws Exception {
@@ -372,7 +497,7 @@
@SmallTest
public void testMtu() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// IP header.
"451001480000000080118849c0a89003c0a89ff7" +
// UDP header.
@@ -391,8 +516,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options
"638253633501023604c0a89003330400001c200104fffff0000304c0a89ffe06080808080808080404" +
- "3a0400000e103b040000189cff00000000"
- ).toCharArray(), false));
+ "3a0400000e103b040000189cff00000000"));
checkMtu(packet, 0, null);
checkMtu(packet, 0, mtuBytes(1501));
@@ -409,7 +533,7 @@
@SmallTest
public void testBadHwaddrLength() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// IP header.
"450001518d0600004011144dc0a82b01c0a82bf7" +
// UDP header.
@@ -428,8 +552,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options
"638253633501023604c0a82b01330400000e103a04000007083b0400000c4e0104ffffff00" +
- "1c04c0a82bff0304c0a82b010604c0a82b012b0f414e44524f49445f4d455445524544ff"
- ).toCharArray(), false));
+ "1c04c0a82bff0304c0a82b010604c0a82b012b0f414e44524f49445f4d455445524544ff"));
String expectedClientMac = "30766FF2A90C";
final int hwAddrLenOffset = 20 + 8 + 2;
@@ -486,7 +609,7 @@
// store any information in the overloaded fields).
//
// For now, we just check that it parses correctly.
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// Ethernet header.
"b4cef6000000e80462236e300800" +
// IP header.
@@ -507,8 +630,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options
"638253633501023604010101010104ffff000033040000a8c03401030304ac1101010604ac110101" +
- "0000000000000000000000000000000000000000000000ff000000"
- ).toCharArray(), false));
+ "0000000000000000000000000000000000000000000000ff000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
assertTrue(offerPacket instanceof DhcpOfferPacket);
@@ -519,7 +641,7 @@
@SmallTest
public void testBug2111() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// IP header.
"4500014c00000000ff119beac3eaf3880a3f5d04" +
// UDP header. TODO: fix invalid checksum (due to MAC address obfuscation).
@@ -538,8 +660,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options.
"638253633501023604c00002fe33040000bfc60104fffff00003040a3f50010608c0000201c0000202" +
- "0f0f646f6d61696e3132332e636f2e756b0000000000ff00000000"
- ).toCharArray(), false));
+ "0f0f646f6d61696e3132332e636f2e756b0000000000ff00000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L3);
assertTrue(offerPacket instanceof DhcpOfferPacket);
@@ -550,7 +671,7 @@
@SmallTest
public void testBug2136() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// Ethernet header.
"bcf5ac000000d0c7890000000800" +
// IP header.
@@ -571,8 +692,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options.
"6382536335010236040a20ff80330400001c200104fffff00003040a20900106089458413494584135" +
- "0f0b6c616e63732e61632e756b000000000000000000ff00000000"
- ).toCharArray(), false));
+ "0f0b6c616e63732e61632e756b000000000000000000ff00000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
assertTrue(offerPacket instanceof DhcpOfferPacket);
@@ -584,7 +704,7 @@
@SmallTest
public void testUdpServerAnySourcePort() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// Ethernet header.
"9cd917000000001c2e0000000800" +
// IP header.
@@ -606,8 +726,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options.
"6382536335010236040a0169fc3304000151800104ffff000003040a0fc817060cd1818003d1819403" +
- "d18180060f0777766d2e6564751c040a0fffffff000000"
- ).toCharArray(), false));
+ "d18180060f0777766d2e6564751c040a0fffffff000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
assertTrue(offerPacket instanceof DhcpOfferPacket);
@@ -620,7 +739,7 @@
@SmallTest
public void testUdpInvalidDstPort() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// Ethernet header.
"9cd917000000001c2e0000000800" +
// IP header.
@@ -642,8 +761,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options.
"6382536335010236040a0169fc3304000151800104ffff000003040a0fc817060cd1818003d1819403" +
- "d18180060f0777766d2e6564751c040a0fffffff000000"
- ).toCharArray(), false));
+ "d18180060f0777766d2e6564751c040a0fffffff000000"));
try {
DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
@@ -653,7 +771,7 @@
@SmallTest
public void testMultipleRouters() throws Exception {
- final ByteBuffer packet = ByteBuffer.wrap(HexEncoding.decode((
+ final ByteBuffer packet = ByteBuffer.wrap(HexDump.hexStringToByteArray(
// Ethernet header.
"fc3d93000000" + "081735000000" + "0800" +
// IP header.
@@ -674,8 +792,7 @@
"0000000000000000000000000000000000000000000000000000000000000000" +
// Options.
"638253633501023604c0abbd023304000070803a04000038403b04000062700104ffffff00" +
- "0308c0a8bd01ffffff0006080808080808080404ff000000000000"
- ).toCharArray(), false));
+ "0308c0a8bd01ffffff0006080808080808080404ff000000000000"));
DhcpPacket offerPacket = DhcpPacket.decodeFullPacket(packet, ENCAP_L2);
assertTrue(offerPacket instanceof DhcpOfferPacket);
