Function pnet::packet::util::ipv4_checksum

pub fn ipv4_checksum(
    data: &[u8], 
    skipword: usize, 
    extra_data: &[u8], 
    source: &Ipv4Addr, 
    destination: &Ipv4Addr, 
    next_level_protocol: IpNextHeaderProtocol
) -> u16

Calculate the checksum for a packet built on IPv4. Used by UDP and TCP.