write_udp.rs

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], //destination mac
    )
    .ipv4(
        [192, 168, 1, 1], //source ip
        [192, 168, 1, 2], //destination 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);
}