use std::io;
use std::collections::HashMap;
ust std::net::Ipv4Addr;

mod tcp
;
struct Quad {
    src: (Ipv4Addr, u16),
    dst: (Ipv4Addr, u16)
}

fn main() -> io::Result<()> {
    let mut connections: HashMap<Quad, tcp::State> = Default::default();

  let nic = tun_tap::Iface::new("tun0", tun_tap::Mode::Tun)?;
  let mut buf = [0u8; 1504];
  loop {
      let nbytes = nic.recv(&mut buf[..])?;
      let eth_flags = u16::from_be_bytes([buf[0], buf[1]]);
      let eth_protocol = u16::from_be_bytes([buf[2], buf[3]]);
      if eth_protocol != 0x0800 {
        println!("Got non-ipv4 protocol");
        continue; // ethernet protocol is not ipv4
      }

      match etherparse::Ipv4HeaderSlice::from_slice(&buf[4..nbytes]) {
        Ok(ip_header) => {
              let src = ip_header.source_addr();
              let dst = ip_header.destination_addr();

              if ip_header.protocol() != 0x06 { // Protocol has to be TCP
                continue;
              }

              match etherparse::TcpHeaderSlice::from_slice(&buf[4+ip_header.slice().len()..]) {
                Ok(tcp_header) => {
                    let data_i = 4 + ip_header.slice().len() + tcp_header.slice().len();
                    connections.entry(Quad {
                        src: (src, p.source_port()),
                        dst: (dst, p.destination_port()),
                    }).or_default().on_packet(ip_header, tcp_header, &buf[data_i..]);
                    // (srcip, srcport, dstip, dstport)
                      eprintln!("{} -> {} - {} bytes of TCP to port {}",    src, dst,   tcp_header.slice().len(), tcp_header.destination_port());
                },
                Err(e) => {
                    eprintln!("Ignoring TCP packet {:?}", e);
                }
              }
        },
        Err(e) => {
            eprintln!("Ignoring weird packet {:?}", e);
        }
      }
  }
}