Improve the resiliency of the packet deserialization code.
Packet deserializers now check for malformed input while reading the byte
stream. Deserializers are re-implemented as functions that take a byte array
and return a packet object. The old IPacket.deserialize(...) methods have been
deprecated with the goal of eventually moving to immutable packet objects.
Unit tests have been implemented for all Deserializer functions.
ONOS-1589
Change-Id: I9073d5e6e7991e15d43830cfd810989256b71c56
diff --git a/utils/misc/src/main/java/org/onlab/packet/DHCP.java b/utils/misc/src/main/java/org/onlab/packet/DHCP.java
index 8dba13c..40a7745 100644
--- a/utils/misc/src/main/java/org/onlab/packet/DHCP.java
+++ b/utils/misc/src/main/java/org/onlab/packet/DHCP.java
@@ -24,6 +24,8 @@
import java.util.List;
import java.util.ListIterator;
+import static org.onlab.packet.PacketUtils.*;
+
/**
*
*/
@@ -429,33 +431,9 @@
return data;
}
- protected void writeString(final String string, final ByteBuffer bb,
- final int maxLength) {
- if (string == null) {
- for (int i = 0; i < maxLength; ++i) {
- bb.put((byte) 0x0);
- }
- } else {
- byte[] bytes = null;
- try {
- bytes = string.getBytes("ascii");
- } catch (final UnsupportedEncodingException e) {
- throw new RuntimeException("Failure encoding server name", e);
- }
- int writeLength = bytes.length;
- if (writeLength > maxLength) {
- writeLength = maxLength;
- }
- bb.put(bytes, 0, writeLength);
- for (int i = writeLength; i < maxLength; ++i) {
- bb.put((byte) 0x0);
- }
- }
- }
-
@Override
public IPacket deserialize(final byte[] data, final int offset,
- final int length) {
+ final int length) {
final ByteBuffer bb = ByteBuffer.wrap(data, offset, length);
if (bb.remaining() < DHCP.MIN_HEADER_LENGTH) {
return this;
@@ -529,7 +507,31 @@
return this;
}
- protected String readString(final ByteBuffer bb, final int maxLength) {
+ protected void writeString(final String string, final ByteBuffer bb,
+ final int maxLength) {
+ if (string == null) {
+ for (int i = 0; i < maxLength; ++i) {
+ bb.put((byte) 0x0);
+ }
+ } else {
+ byte[] bytes = null;
+ try {
+ bytes = string.getBytes("ascii");
+ } catch (final UnsupportedEncodingException e) {
+ throw new RuntimeException("Failure encoding server name", e);
+ }
+ int writeLength = bytes.length;
+ if (writeLength > maxLength) {
+ writeLength = maxLength;
+ }
+ bb.put(bytes, 0, writeLength);
+ for (int i = writeLength; i < maxLength; ++i) {
+ bb.put((byte) 0x0);
+ }
+ }
+ }
+
+ private static String readString(final ByteBuffer bb, final int maxLength) {
final byte[] bytes = new byte[maxLength];
bb.get(bytes);
String result = null;
@@ -540,4 +542,84 @@
}
return result;
}
+
+ /**
+ * Deserializer function for DHCP packets.
+ *
+ * @return deserializer function
+ */
+ public static Deserializer<DHCP> deserializer() {
+ return (data, offset, length) -> {
+ checkInput(data, offset, length, MIN_HEADER_LENGTH);
+
+ ByteBuffer bb = ByteBuffer.wrap(data, offset, length);
+ DHCP dhcp = new DHCP();
+
+ dhcp.opCode = bb.get();
+ dhcp.hardwareType = bb.get();
+ dhcp.hardwareAddressLength = bb.get();
+ dhcp.hops = bb.get();
+ dhcp.transactionId = bb.getInt();
+ dhcp.seconds = bb.getShort();
+ dhcp.flags = bb.getShort();
+ dhcp.clientIPAddress = bb.getInt();
+ dhcp.yourIPAddress = bb.getInt();
+ dhcp.serverIPAddress = bb.getInt();
+ dhcp.gatewayIPAddress = bb.getInt();
+ final int hardwareAddressLength = 0xff & dhcp.hardwareAddressLength;
+ dhcp.clientHardwareAddress = new byte[hardwareAddressLength];
+
+ bb.get(dhcp.clientHardwareAddress);
+ for (int i = hardwareAddressLength; i < 16; ++i) {
+ bb.get();
+ }
+ dhcp.serverName = readString(bb, 64);
+ dhcp.bootFileName = readString(bb, 128);
+ // read the magic cookie
+ // magic cookie
+ bb.get();
+ bb.get();
+ bb.get();
+ bb.get();
+
+ // read options
+ boolean foundEndOptionsMarker = false;
+ while (bb.hasRemaining()) {
+ final DHCPOption option = new DHCPOption();
+ int code = 0xff & bb.get(); // convert signed byte to int in range
+ // [0,255]
+ option.setCode((byte) code);
+ if (code == 0) {
+ // skip these
+ continue;
+ } else if (code != 255) {
+ if (bb.hasRemaining()) {
+ final int l = 0xff & bb.get(); // convert signed byte to
+ // int in range [0,255]
+ option.setLength((byte) l);
+ if (bb.remaining() >= l) {
+ final byte[] optionData = new byte[l];
+ bb.get(optionData);
+ option.setData(optionData);
+ dhcp.options.add(option);
+ } else {
+ throw new DeserializationException(
+ "Buffer underflow while reading DHCP option");
+ }
+ }
+ } else if (code == 255) {
+ // remaining bytes are supposed to be 0, but ignore them just in
+ // case
+ foundEndOptionsMarker = true;
+ break;
+ }
+ }
+
+ if (!foundEndOptionsMarker) {
+ throw new DeserializationException("DHCP End options marker was missing");
+ }
+
+ return dhcp;
+ };
+ }
}