/*_##########################################################################
_##
_## Copyright (C) 2012 Kaito Yamada
_##
_##########################################################################
*/
package org.pcap4j.util;
import org.pcap4j.packet.ChecksumBuilder;
import org.pcap4j.packet.LengthBuilder;
import org.pcap4j.packet.Packet;
import org.pcap4j.packet.UnknownPacket;
/**
* @author Kaito Yamada
* @since pcap4j 0.9.11
*/
public final class IcmpV6Helper {
private IcmpV6Helper() { throw new AssertionError(); }
/**
*
* @param packet an IPv6 Packet
* @param size the target size in bytes. (i.e. MTU - <IPv6 header(s) size> - <ICMPv6 header size>)
* @return a new IPv6 packet object.
*/
public static Packet makePacketForInvokingPacketField(Packet packet, int size) {
if (
packet == null
|| packet.getHeader() == null
|| packet.getPayload() == null
) {
StringBuilder sb = new StringBuilder();
sb.append("packet: ").append(packet)
.append(" packet.getHeader(): ").append(packet.getHeader())
.append(" packet.getPayload(): ").append(packet.getPayload());
throw new NullPointerException(sb.toString());
}
if (packet.length() <= size) {
return packet;
}
int length = packet.getHeader().length();
int prelength = length;
int pos = 0;
Packet last = null;
for (Packet p: packet.getPayload()) {
if (p.getHeader() != null) {
prelength = length;
length += p.getHeader().length();
pos++;
if (length > size) {
last = p;
break;
}
}
else {
prelength = length;
length += p.length();
pos++;
last = p;
break;
}
}
Packet.Builder resultBuilder = packet.getBuilder();
for (Packet.Builder b: resultBuilder) {
if (b instanceof LengthBuilder) {
((LengthBuilder<?>)b).correctLengthAtBuild(false);
}
if (b instanceof ChecksumBuilder) {
((ChecksumBuilder<?>)b).correctChecksumAtBuild(false);
}
pos--;
if (pos == 0) {
if (size - prelength > 0) {
b.payloadBuilder(
new UnknownPacket.Builder()
.rawData(
ByteArrays.getSubArray(last.getRawData(), 0, size - prelength)
)
);
}
else {
b.payloadBuilder(null);
}
break;
}
}
return resultBuilder.build();
}
/**
*
* @param packet an IPv6 Packet
* @param size the target size in bytes. (i.e. MTU - <IPv6 header(s) size> - <ICMPv6 header size> - <IPv6 ND option(s) size>)
* @return a new IPv6 packet object.
*/
public static Packet makePacketForRedirectHeaderOption(Packet packet, int size) {
if (packet.length() > size) {
return makePacketForInvokingPacketField(packet, size - size % 8);
}
else {
int length = packet.length();
return makePacketForInvokingPacketField(packet, length - length % 8);
}
}
}