write_udp.rs

extern crate etherparse;
use etherparse::*;

fn main() {

    //setup the packet headers
    let builder = PacketBuilder::
    ethernet2([1,2,3,4,5,6],     //source mac
               [7,8,9,10,11,12]) //destionation mac
    .ipv4([192,168,1,1], //source ip
          [192,168,1,2], //desitionation ip
          20)            //time to life
    .udp(21,    //source port 
         1234); //desitnation port

    //payload of the udp packet
    let payload = [1,2,3,4,5,6,7,8];
    
    //get some memory to store the result
    let mut result = Vec::<u8>::with_capacity(
                    builder.size(payload.len()));
    
    //serialize
    //this will automatically set all length fields, checksums and identifiers (ethertype & protocol)
    builder.write(&mut result, &payload).unwrap();
    println!("{:?}", result);
}