third_party/rust_crates/forks/netlink-packet-route-0.20.0/examples/dump_rules.rs

// SPDX-License-Identifier: MIT

use netlink_packet_core::{
    NetlinkHeader, NetlinkMessage, NetlinkPayload, NLM_F_DUMP, NLM_F_REQUEST,
};
use netlink_packet_route::{rule::RuleMessage, RouteNetlinkMessage};
use netlink_sys::{protocols::NETLINK_ROUTE, Socket, SocketAddr};

fn main() {
    let mut socket = Socket::new(NETLINK_ROUTE).unwrap();
    let _port_number = socket.bind_auto().unwrap().port_number();
    socket.connect(&SocketAddr::new(0, 0)).unwrap();

    let mut nl_hdr = NetlinkHeader::default();
    nl_hdr.flags = NLM_F_REQUEST | NLM_F_DUMP;
    let mut packet = NetlinkMessage::new(
        nl_hdr,
        NetlinkPayload::from(RouteNetlinkMessage::GetRule(
            RuleMessage::default(),
        )),
    );

    packet.finalize();

    let mut buf = vec![0; packet.header.length as usize];

    // Before calling serialize, it is important to check that the buffer in
    // which we're emitting is big enough for the packet, other
    // `serialize()` panics.

    assert!(buf.len() == packet.buffer_len());

    packet.serialize(&mut buf[..]);

    println!(">>> {packet:?}");
    if let Err(e) = socket.send(&buf[..], 0) {
        println!("SEND ERROR {e}");
    }

    let mut receive_buffer = vec![0; 4096];
    let mut offset = 0;

    // we set the NLM_F_DUMP flag so we expect a multipart rx_packet in
    // response.
    while let Ok(size) = socket.recv(&mut &mut receive_buffer[..], 0) {
        loop {
            let bytes = &receive_buffer[offset..];
            let rx_packet =
                <NetlinkMessage<RouteNetlinkMessage>>::deserialize(bytes)
                    .unwrap();
            println!("<<< {rx_packet:?}");

            if matches!(rx_packet.payload, NetlinkPayload::Done(_)) {
                println!("Done!");
                return;
            }

            offset += rx_packet.header.length as usize;
            if offset == size || rx_packet.header.length == 0 {
                offset = 0;
                break;
            }
        }
    }
}