libnet_getpacket_size();

Ok I wrote it. It will be in the latest release, probably 1.1.2 this 
week.

[rounder:Projects/libnet/sample] root# grep -2 getpacket udp1.c
          */
         fprintf(stderr, "%d byte packet, ready to go\n",
             libnet_getpacket_size(l));
         /* __libnet_dump_pblock(l); */
         c = libnet_write(l);

rounder:Projects/libnet/sample] root# ./udp1 -s 2.2.2.2.111 -d 
2.2.2.2.222 -p.....................................................
libnet 1.1 packet shaping: UDP + IP options[raw]
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
101 byte packet, ready to go
Wrote 101 byte UDP packet; check the wire.
Packets sent:  10
Packet errors: 0
Bytes written: 1010

--
Mike Schiffman, CISSP
http://www.packetfactory.net/schiffman
Doveryay No Proveryay