Example #1
0
func responsePacket(local net.IP, remote net.IP, lPort uint16, rPort uint16, respPayload []byte) *udpPacket {
	ip := packet.NewIPv4()
	udp := packet.NewUDP()

	ip.Version = 4
	ip.SrcIP = make(net.IP, len(remote))
	copy(ip.SrcIP, remote)
	ip.DstIP = make(net.IP, len(local))
	copy(ip.DstIP, local)
	ip.TTL = 64
	ip.Protocol = packet.IPProtocolUDP

	udp.SrcPort = rPort
	udp.DstPort = lPort
	udp.Payload = respPayload

	pkt := newUDPPacket()
	pkt.ip = ip
	pkt.udp = udp

	buf := newBuffer()
	pkt.mtuBuf = buf

	payloadL := len(udp.Payload)
	payloadStart := MTU - payloadL
	if payloadL != 0 {
		copy(pkt.mtuBuf[payloadStart:], udp.Payload)
	}
	udpHL := 8
	udpStart := payloadStart - udpHL
	pseduoStart := udpStart - packet.IPv4_PSEUDO_LENGTH
	ip.PseudoHeader(pkt.mtuBuf[pseduoStart:udpStart], packet.IPProtocolUDP, udpHL+payloadL)
	udp.Serialize(pkt.mtuBuf[udpStart:payloadStart], pkt.mtuBuf[pseduoStart:])
	ipHL := ip.HeaderLength()
	ipStart := udpStart - ipHL
	ip.Serialize(pkt.mtuBuf[ipStart:udpStart], udpHL+payloadL)

	pkt.wire = pkt.mtuBuf[ipStart:]
	return pkt
}
Example #2
0
func copyUDPPacket(raw []byte, ip *packet.IPv4, udp *packet.UDP) *udpPacket {
	iphdr := packet.NewIPv4()
	udphdr := packet.NewUDP()
	pkt := newUDPPacket()
	if len(udp.Payload) == 0 {
		// shallow copy headers
		// for now, we don't need deep copy if no payload
		*iphdr = *ip
		*udphdr = *udp
		pkt.ip = iphdr
		pkt.udp = udphdr
	} else {
		// get a block of buffer, make a deep copy
		buf := newBuffer()
		n := copy(buf, raw)
		pkt.mtuBuf = buf
		pkt.wire = buf[:n]
		packet.ParseIPv4(pkt.wire, iphdr)
		packet.ParseUDP(iphdr.Payload, udphdr)
		pkt.ip = iphdr
		pkt.udp = udphdr
	}
	return pkt
}