parse_packet.rs

use smoltcp::wire::{IpProtocol, Ipv4Packet, Ipv6Packet};

fn extract_udp_packet(packet: &[u8]) -> Result<UdpPacket, Box<dyn std::error::Error>> {
    if let Ok(ipv4_packet) = Ipv4Packet::new_checked(packet) {
        let src_addr = ipv4_packet.src_addr();
        let dst_addr = ipv4_packet.dst_addr();
        let protocol = ipv4_packet.next_header();
        let payload = ipv4_packet.payload();
        if protocol == IpProtocol::Udp {
            let udp_packet = smoltcp::wire::UdpPacket::new_checked(payload)?;
            let src_port = udp_packet.src_port();
            let dst_port = udp_packet.dst_port();
            let src_addr = SocketAddr::new(Ipv4Addr::from(src_addr).into(), src_port);
            let dst_addr = SocketAddr::new(Ipv4Addr::from(dst_addr).into(), dst_port);
            let data = udp_packet.payload();
            let udp_packet = UdpPacket::new(src_addr, dst_addr, data);
            return Ok(udp_packet);
        }
    } else {
        let ipv6_packet = Ipv6Packet::new_checked(packet)?;
        let src_addr = ipv6_packet.src_addr();
        let dst_addr = ipv6_packet.dst_addr();
        let protocol = ipv6_packet.next_header();
        let payload = ipv6_packet.payload();
        if protocol == IpProtocol::Udp {
            let udp_packet = smoltcp::wire::UdpPacket::new_checked(payload)?;
            let src_port = udp_packet.src_port();
            let dst_port = udp_packet.dst_port();
            let src_addr = SocketAddr::new(Ipv6Addr::from(src_addr).into(), src_port);
            let dst_addr = SocketAddr::new(Ipv6Addr::from(dst_addr).into(), dst_port);
            let data = udp_packet.payload();
            let udp_packet = UdpPacket::new(src_addr, dst_addr, data);
            return Ok(udp_packet);
        }
    }
    Err("Packet is not a UDP packet".into())
}