294 lines
8.0 KiB
Rust
294 lines
8.0 KiB
Rust
use std::{
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mem::MaybeUninit,
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net::{IpAddr, Ipv4Addr, SocketAddrV4},
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sync::Arc,
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thread,
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};
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use pnet::packet::{
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icmp::{self, IcmpTypes},
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ip::IpNextHeaderProtocols,
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ipv4::{self, Ipv4Packet, MutableIpv4Packet},
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Packet,
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};
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use socket2::Socket;
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use tokio::{
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sync::{mpsc::UnboundedSender, Mutex},
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task::JoinSet,
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};
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use tokio_util::bytes::Bytes;
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use tracing::Instrument;
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use crate::{
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common::{error::Error, global_ctx::ArcGlobalCtx, PeerId},
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peers::{packet, peer_manager::PeerManager, PeerPacketFilter},
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};
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use super::CidrSet;
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#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
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struct IcmpNatKey {
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dst_ip: std::net::IpAddr,
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icmp_id: u16,
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icmp_seq: u16,
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}
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#[derive(Debug)]
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struct IcmpNatEntry {
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src_peer_id: PeerId,
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my_peer_id: PeerId,
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src_ip: IpAddr,
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start_time: std::time::Instant,
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}
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impl IcmpNatEntry {
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fn new(src_peer_id: PeerId, my_peer_id: PeerId, src_ip: IpAddr) -> Result<Self, Error> {
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Ok(Self {
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src_peer_id,
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my_peer_id,
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src_ip,
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start_time: std::time::Instant::now(),
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})
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}
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}
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type IcmpNatTable = Arc<dashmap::DashMap<IcmpNatKey, IcmpNatEntry>>;
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type NewPacketSender = tokio::sync::mpsc::UnboundedSender<IcmpNatKey>;
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type NewPacketReceiver = tokio::sync::mpsc::UnboundedReceiver<IcmpNatKey>;
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#[derive(Debug)]
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pub struct IcmpProxy {
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global_ctx: ArcGlobalCtx,
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peer_manager: Arc<PeerManager>,
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cidr_set: CidrSet,
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socket: socket2::Socket,
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nat_table: IcmpNatTable,
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tasks: Mutex<JoinSet<()>>,
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}
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fn socket_recv(socket: &Socket, buf: &mut [MaybeUninit<u8>]) -> Result<(usize, IpAddr), Error> {
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let (size, addr) = socket.recv_from(buf)?;
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let addr = match addr.as_socket() {
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None => IpAddr::V4(Ipv4Addr::UNSPECIFIED),
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Some(add) => add.ip(),
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};
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Ok((size, addr))
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}
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fn socket_recv_loop(
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socket: Socket,
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nat_table: IcmpNatTable,
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sender: UnboundedSender<packet::Packet>,
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) {
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let mut buf = [0u8; 4096];
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let data: &mut [MaybeUninit<u8>] = unsafe { std::mem::transmute(&mut buf[12..]) };
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loop {
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let Ok((len, peer_ip)) = socket_recv(&socket, data) else {
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continue;
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};
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if !peer_ip.is_ipv4() {
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continue;
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}
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let Some(mut ipv4_packet) = MutableIpv4Packet::new(&mut buf[12..12 + len]) else {
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continue;
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};
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let Some(icmp_packet) = icmp::echo_reply::EchoReplyPacket::new(ipv4_packet.payload())
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else {
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continue;
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};
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if icmp_packet.get_icmp_type() != IcmpTypes::EchoReply {
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continue;
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}
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let key = IcmpNatKey {
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dst_ip: peer_ip,
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icmp_id: icmp_packet.get_identifier(),
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icmp_seq: icmp_packet.get_sequence_number(),
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};
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let Some((_, v)) = nat_table.remove(&key) else {
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continue;
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};
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// send packet back to the peer where this request origin.
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let IpAddr::V4(dest_ip) = v.src_ip else {
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continue;
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};
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ipv4_packet.set_destination(dest_ip);
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ipv4_packet.set_checksum(ipv4::checksum(&ipv4_packet.to_immutable()));
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let peer_packet = packet::Packet::new_data_packet(
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v.my_peer_id,
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v.src_peer_id,
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&ipv4_packet.to_immutable().packet(),
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);
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if let Err(e) = sender.send(peer_packet) {
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tracing::error!("send icmp packet to peer failed: {:?}, may exiting..", e);
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break;
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}
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}
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}
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#[async_trait::async_trait]
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impl PeerPacketFilter for IcmpProxy {
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async fn try_process_packet_from_peer(
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&self,
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packet: &packet::ArchivedPacket,
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_: &Bytes,
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) -> Option<()> {
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let _ = self.global_ctx.get_ipv4()?;
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if packet.packet_type != packet::PacketType::Data {
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return None;
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};
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let ipv4 = Ipv4Packet::new(&packet.payload.as_bytes())?;
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if ipv4.get_version() != 4 || ipv4.get_next_level_protocol() != IpNextHeaderProtocols::Icmp
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{
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return None;
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}
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if !self.cidr_set.contains_v4(ipv4.get_destination()) {
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return None;
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}
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let icmp_packet = icmp::echo_request::EchoRequestPacket::new(&ipv4.payload())?;
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if icmp_packet.get_icmp_type() != IcmpTypes::EchoRequest {
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// drop it because we do not support other icmp types
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tracing::trace!("unsupported icmp type: {:?}", icmp_packet.get_icmp_type());
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return Some(());
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}
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let icmp_id = icmp_packet.get_identifier();
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let icmp_seq = icmp_packet.get_sequence_number();
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let key = IcmpNatKey {
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dst_ip: ipv4.get_destination().into(),
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icmp_id,
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icmp_seq,
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};
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let value = IcmpNatEntry::new(
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packet.from_peer.into(),
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packet.to_peer.into(),
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ipv4.get_source().into(),
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)
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.ok()?;
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if let Some(old) = self.nat_table.insert(key, value) {
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tracing::info!("icmp nat table entry replaced: {:?}", old);
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}
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if let Err(e) = self.send_icmp_packet(ipv4.get_destination(), &icmp_packet) {
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tracing::error!("send icmp packet failed: {:?}", e);
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}
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Some(())
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}
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}
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impl IcmpProxy {
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pub fn new(
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global_ctx: ArcGlobalCtx,
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peer_manager: Arc<PeerManager>,
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) -> Result<Arc<Self>, Error> {
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let cidr_set = CidrSet::new(global_ctx.clone());
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let _g = global_ctx.net_ns.guard();
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let socket = socket2::Socket::new(
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socket2::Domain::IPV4,
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socket2::Type::RAW,
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Some(socket2::Protocol::ICMPV4),
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)?;
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socket.bind(&socket2::SockAddr::from(SocketAddrV4::new(
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std::net::Ipv4Addr::UNSPECIFIED,
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0,
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)))?;
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let ret = Self {
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global_ctx,
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peer_manager,
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cidr_set,
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socket,
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nat_table: Arc::new(dashmap::DashMap::new()),
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tasks: Mutex::new(JoinSet::new()),
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};
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Ok(Arc::new(ret))
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}
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pub async fn start(self: &Arc<Self>) -> Result<(), Error> {
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self.start_icmp_proxy().await?;
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self.start_nat_table_cleaner().await?;
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Ok(())
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}
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async fn start_nat_table_cleaner(self: &Arc<Self>) -> Result<(), Error> {
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let nat_table = self.nat_table.clone();
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self.tasks.lock().await.spawn(
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async move {
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loop {
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tokio::time::sleep(std::time::Duration::from_secs(1)).await;
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nat_table.retain(|_, v| v.start_time.elapsed().as_secs() < 20);
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}
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}
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.instrument(tracing::info_span!("icmp proxy nat table cleaner")),
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);
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Ok(())
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}
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async fn start_icmp_proxy(self: &Arc<Self>) -> Result<(), Error> {
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let socket = self.socket.try_clone()?;
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let (sender, mut receiver) = tokio::sync::mpsc::unbounded_channel();
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let nat_table = self.nat_table.clone();
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thread::spawn(|| {
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socket_recv_loop(socket, nat_table, sender);
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});
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let peer_manager = self.peer_manager.clone();
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self.tasks.lock().await.spawn(
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async move {
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while let Some(msg) = receiver.recv().await {
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let to_peer_id = msg.to_peer.into();
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let ret = peer_manager.send_msg(msg.into(), to_peer_id).await;
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if ret.is_err() {
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tracing::error!("send icmp packet to peer failed: {:?}", ret);
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}
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}
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}
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.instrument(tracing::info_span!("icmp proxy send loop")),
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);
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self.peer_manager
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.add_packet_process_pipeline(Box::new(self.clone()))
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.await;
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Ok(())
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}
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fn send_icmp_packet(
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&self,
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dst_ip: Ipv4Addr,
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icmp_packet: &icmp::echo_request::EchoRequestPacket,
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) -> Result<(), Error> {
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self.socket.send_to(
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icmp_packet.packet(),
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&SocketAddrV4::new(dst_ip.into(), 0).into(),
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)?;
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Ok(())
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}
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}
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