feat: started to make a TCP state machine
This commit is contained in:
Andrew Rioux
parent
f092548a8c
commit
ed13defb07
GPG Key ID:
9B8BAC47C17ABB94
@ -9,9 +9,13 @@ use pcap_sys::packets::*;
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#[tokio::main]
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async fn main() -> anyhow::Result<()> {
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let target = std::env::args().skip(1).next().ok_or(anyhow!("could not get target IP"))?.parse::<Ipv4Addr>()?;
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let target = std::env::args()
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.skip(1)
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.next()
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.ok_or(anyhow!("could not get target IP"))?
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.parse::<Ipv4Addr>()?;
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let (ifname, src_mac, dst_mac, srcip) = {
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let (ifname, _, srcip, src_mac, dst_mac, _) = {
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let socket = netlink::Socket::new()?;
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let routes = socket.get_routes()?;
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@ -19,11 +23,8 @@ async fn main() -> anyhow::Result<()> {
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let links = socket.get_links()?;
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let addrs = socket.get_addrs()?;
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let (ifname, srcip, srcmac, dstmac) =
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route::get_macs_and_src_for_ip(&addrs, &routes, &neighs, &links, target)
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.ok_or(anyhow!("unable to find a route to the IP"))?;
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(ifname, srcmac, dstmac, srcip)
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.ok_or(anyhow!("unable to find a route to the IP"))?
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};
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let mut interface = pcap_sys::new_aggregate_interface(false)?;
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@ -56,12 +57,18 @@ async fn main() -> anyhow::Result<()> {
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match evt {
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EventType::Packet((_, Ok(pkt))) => {
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let eth_pkt = pkt.pkt();
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let Ok(Layer3Pkt::IPv4Pkt(ip_pkt)) = eth_pkt.get_layer3_pkt() else { continue; };
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let Ok(Layer4Pkt::UDP(udp_pkt)) = ip_pkt.get_layer4_packet() else { continue; };
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let Ok(Layer3Pkt::IPv4Pkt(ip_pkt)) = eth_pkt.get_layer3_pkt() else {
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continue;
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};
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let Ok(Layer4Pkt::UDP(udp_pkt)) = ip_pkt.get_layer4_packet() else {
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continue;
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};
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let data = udp_pkt.get_data();
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let Ok(resp_id) = TryInto::<[u8;4]>::try_into(&data[..4]) else { continue; };
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let Ok(resp_id) = TryInto::<[u8; 4]>::try_into(&data[..4]) else {
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continue;
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};
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let resp_id = i32::from_be_bytes(resp_id);
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if sent_updates.contains_key(&resp_id) {
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@ -577,7 +577,13 @@ impl TCPPacketBuilder {
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self
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}
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pub fn build<I1, I2>(self, srcip: I1, dstip: I2, data: Vec<u8>) -> TCPPacket
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pub fn build<I1, I2>(
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self,
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srcip: I1,
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dstip: I2,
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data: Vec<u8>,
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checksum_offset: Option<u16>,
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) -> TCPPacket
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where
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I1: Into<Ipv4Addr>,
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I2: Into<Ipv4Addr>,
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@ -626,10 +632,7 @@ impl TCPPacketBuilder {
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}
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})
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.fold(0u32, |acc, e| acc + e)
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+ 30;
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// + 30 to intentionally deviate from
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// the RFC, to make it so that I can identify the packets as sparse
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// packets
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+ (checksum_offset.unwrap_or(0) as u32);
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let checksum = (checksum >> 16) + (checksum & 0xffff);
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let checksum = ((checksum >> 16) as u16) + (checksum as u16);
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@ -645,3 +648,33 @@ impl TCPPacketBuilder {
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}
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}
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}
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#[cfg(test)]
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mod test {
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use std::net::Ipv4Addr;
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use crate::TCPPacketBuilder;
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#[test]
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fn test_checksum() {
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let tcp_packet = TCPPacketBuilder::default()
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.srcport(57116)
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.dstport(54248)
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.seqnumber(0xaed77262)
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.acknumber(0)
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.syn(true)
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.window(64240)
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.options(vec![
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0x02, 0x04, 0x05, 0xb4, 0x04, 0x02, 0x08, 0x0a, 0xd4, 0x06, 0xdf, 0x18, 0x00, 0x00,
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0x00, 0x00, 0x01, 0x03, 0x03, 0x07,
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])
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.build(
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Ipv4Addr::new(10, 104, 18, 67),
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Ipv4Addr::new(10, 104, 21, 16),
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vec![],
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None,
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);
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assert_eq!(tcp_packet.pkt().checksum(), 0x898d);
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}
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}
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@ -1,18 +1,94 @@
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use std::{net::Ipv4Addr, os::fd::AsRawFd, sync::Arc};
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use std::{
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collections::VecDeque,
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net::{Ipv4Addr, SocketAddr},
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};
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use anyhow::anyhow;
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use log::{debug, info, trace};
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use nl_sys::{netlink, route};
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use smoltcp::{
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iface::{Config, Interface, Route, SocketSet},
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phy::{wait as phy_wait, Device, Medium, RawSocket},
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socket::tcp,
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time::Instant,
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wire::{EthernetAddress, IpAddress, IpCidr, Ipv4Address},
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use packets::{self, EthernetPacket, IPv4Pkt, TCPPacket, TCPPkt};
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use pcap_sys;
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struct PeerInfo {
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remote_addr: Ipv4Addr,
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remote_port: u16,
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local_addr: Ipv4Addr,
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local_port: u16,
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}
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#[derive(Default)]
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struct TcpSocket {
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tx_buffer: VecDeque<u8>,
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rx_buffer: VecDeque<u8>,
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local_seq_no: u32,
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remote_seq_no: u32,
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remote_last_ack: Option<u32>,
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remote_last_win: u16,
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local_rx_last_seq: Option<u32>,
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local_rx_last_ack: Option<u32>,
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state: TcpState,
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peer_info: Option<PeerInfo>,
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}
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#[derive(Default)]
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enum TcpState {
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Listen,
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SynSent,
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SynReceived,
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Established,
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FinWait1,
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FinWait2,
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CloseWait,
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Closing,
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LastAck,
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TimeWait,
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#[default]
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Closed,
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}
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fn socket_accepts_packet(socket: &TcpSocket, ip: IPv4Pkt<'_>, tcp: TCPPkt<'_>) -> bool {
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if let Some(peer) = &socket.peer_info {
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peer.local_addr == ip.dest_ip()
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&& peer.remote_addr == ip.source_ip()
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&& peer.local_port == tcp.dstport()
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&& peer.remote_port == tcp.srcport()
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} else {
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false
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}
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}
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fn connect(
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socket: &mut TcpSocket,
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remote_addr: Ipv4Addr,
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remote_port: u16,
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local_addr: Ipv4Addr,
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) -> anyhow::Result<TCPPacket> {
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socket.state = TcpState::SynSent;
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let local_port: u16 = loop {
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let port = rand::random();
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if port > 40000 {
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break port;
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}
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};
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use tokio::io::{unix::AsyncFd, Interest};
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socket.peer_info = Some(PeerInfo {
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remote_addr,
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remote_port,
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local_addr,
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local_port,
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});
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Ok(())
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}
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fn process_packet(socket: &mut TcpSocket, packet: TCPPkt<'_>) -> anyhow::Result<Option<TCPPacket>> {
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match socket.state {
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TcpState::SynSent if packet.ack() && packet.syn() => {}
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_ => {}
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}
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Ok(None)
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}
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#[tokio::main]
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async fn main() -> anyhow::Result<()> {
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@ -41,193 +117,7 @@ async fn main() -> anyhow::Result<()> {
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(routes, res)
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};
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// dbg!((&ifname, srcip, src_mac, dst_mac));
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let socket = TcpSocket::default();
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let mut device = RawSocket::new(&ifname, Medium::Ethernet)?;
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let mut config = Config::new(EthernetAddress(src_mac).into());
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config.random_seed = rand::random();
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let mut iface = Interface::new(config, &mut device, Instant::now());
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iface.update_ip_addrs(|ip_addrs| {
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let o = srcip.octets();
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debug!(
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"source network ip: {}.{}.{}.{}/{src_snmask}",
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o[0], o[1], o[2], o[3]
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);
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ip_addrs
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.push(IpCidr::new(
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IpAddress::v4(o[0], o[1], o[2], o[3]),
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src_snmask,
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))
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.unwrap();
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});
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for route in routes.iter() {
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let Some(dst) = route.dst() else {
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trace!("failed to get route destination");
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continue;
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};
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let Some(hop) = route.hop_iter().next() else {
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trace!("no next hop existed for {dst:?}");
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continue;
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};
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if hop.ifindex() != ifindex {
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trace!("hop doesn't match ifindex {ifindex}");
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continue;
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}
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let Some(laddr) = hop.gateway() else {
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trace!("couldn't get gateway address for {dst:?}");
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continue;
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};
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if laddr.atype() != Some(libc::AF_INET) {
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trace!("unable to load IP info for {dst:?}");
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continue;
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}
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if dst.cidrlen() == 0 {
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info!("setting default route via {:?}", &laddr);
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iface
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.routes_mut()
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.add_default_ipv4_route(Ipv4Address::from_bytes(&laddr.hw_address()))?;
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iface.routes_mut().update(|routes| {
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let lip = laddr.hw_address();
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_ = routes.push(Route {
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cidr: IpCidr::new(IpAddress::v4(10, 0, 0, 0), 8),
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via_router: IpAddress::v4(lip[0], lip[1], lip[2], lip[3]),
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expires_at: None,
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preferred_until: None,
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});
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_ = routes.push(Route {
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cidr: IpCidr::new(IpAddress::v4(172, 16, 0, 0), 12),
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via_router: IpAddress::v4(lip[0], lip[1], lip[2], lip[3]),
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expires_at: None,
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preferred_until: None,
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});
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});
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} else {
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let Some(raddr) = route.dst() else {
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continue;
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};
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if raddr.atype() != Some(libc::AF_INET) {
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continue;
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}
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let lip = laddr.hw_address();
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let rip = raddr.hw_address();
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info!(
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"queueing adding {}.{}.{}.{}/{} via {}.{}.{}.{}",
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rip[0],
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rip[1],
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rip[2],
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rip[3],
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dst.cidrlen(),
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lip[0],
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lip[1],
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lip[2],
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lip[3]
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);
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iface.routes_mut().update(|routes| {
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info!(
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"adding {}.{}.{}.{}/{} via {}.{}.{}.{}",
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rip[0],
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rip[1],
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rip[2],
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rip[3],
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dst.cidrlen(),
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lip[0],
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lip[1],
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lip[2],
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lip[3]
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);
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_ = routes.push(Route {
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cidr: IpCidr::new(
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IpAddress::v4(rip[0], rip[1], rip[2], rip[3]),
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dst.cidrlen() as u8,
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),
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via_router: IpAddress::v4(lip[0], lip[1], lip[2], lip[3]),
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expires_at: None,
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preferred_until: None,
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})
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});
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}
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}
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debug!("routes added:");
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iface.routes_mut().update(|r| {
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for r in r {
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debug!("\t{r:?}");
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}
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});
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let tcp_rx_buffer = tcp::SocketBuffer::new(vec![0; 65536]);
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let tcp_tx_buffer = tcp::SocketBuffer::new(vec![0; 65536]);
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let tcp_socket = tcp::Socket::new(tcp_rx_buffer, tcp_tx_buffer);
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let mut sockets = SocketSet::new(vec![]);
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let tcp_handle = sockets.add(tcp_socket);
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let port = loop {
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let port = rand::random::<u16>();
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if port > 40_000 {
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break port;
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}
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};
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let socket = sockets.get_mut::<tcp::Socket>(tcp_handle);
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socket.connect(iface.context(), (ip, 54248), port)?;
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let fd = device.as_raw_fd();
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/*let interest = Interest::WRITABLE
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.add(Interest::READABLE)
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.add(Interest::ERROR)
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.add(Interest::PRIORITY);
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let afd = AsyncFd::with_interest(fd, interest)?;*/
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let mut tcp_active = false;
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loop {
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let timestamp = Instant::now();
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iface.poll(timestamp, &mut device, &mut sockets);
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let socket = sockets.get_mut::<tcp::Socket>(tcp_handle);
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if socket.is_active() && !tcp_active {
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info!("connected!");
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tcp_active = true;
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} else if !socket.is_active() && tcp_active {
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info!("disconnected");
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tcp_active = false;
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}
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tcp_active = socket.is_active();
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if !socket.is_active() && !tcp_active {
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socket.connect(iface.context(), (ip, 54248), port)?;
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info!("connecting...");
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}
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if socket.can_send() {
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socket.send_slice(b"ping")?;
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info!("sent data!");
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} else if socket.may_recv() {
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socket.recv(|data| {
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if !data.is_empty() {
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match std::str::from_utf8(&data) {
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Ok(s) => info!("Data received: {}", s),
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Err(_) => info!("Data received: {:?}", data),
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}
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}
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(data.len(), data)
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})?;
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}
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phy_wait(fd, iface.poll_delay(timestamp, &sockets))?;
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// drop(afd.ready(interest).await?);
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}
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Ok(())
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}
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