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chore(*) refactor Phantun and fake-tcp to their own crates

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Datong Sun
2021-09-19 00:36:40 -07:00
parent 86c6a3f801
commit 4a9e41b0b7
16 changed files with 677 additions and 20 deletions
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[package]
name = "fake-tcp"
version = "0.1.0"
edition = "2018"
authors = ["Datong Sun <dndx@idndx.com>"]
license = "MIT OR Apache-2.0"
repository = "https://github.com/dndx/phantun"
readme = "README.md"
description = """
A TUN interface based, user space, asynchronous and high performance TCP stack that allows
packet oriented tunneling with minimum overhead.
"""
[dependencies]
bytes = "1"
pnet = "0.28.0"
tokio-tun = "0.3.15"
tokio = { version = "1.11.0", features = ["full"] }
rand = { version = "0.8.4", features = ["small_rng"] }
log = "0.4"

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# fake-tcp
A TUN interface based, user space, asynchronous and high performance TCP stack that allows
packet oriented tunneling with minimum overhead.
## License
Copyright 2021 Datong Sun <dndx@idndx.com>
Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
[https://www.apache.org/licenses/LICENSE-2.0](https://www.apache.org/licenses/LICENSE-2.0)> or the MIT license
<LICENSE-MIT or [https://opensource.org/licenses/MIT](https://opensource.org/licenses/MIT)>, at your
option. Files in the project may not be
copied, modified, or distributed except according to those terms.

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pub mod packet;
use bytes::{Bytes, BytesMut};
use log::{info, trace};
use packet::*;
use pnet::packet::{tcp, Packet};
use rand::prelude::*;
use std::collections::{HashMap, HashSet};
use std::fmt;
use std::net::{Ipv4Addr, SocketAddrV4};
use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::{Arc, RwLock};
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::sync::mpsc::{self, Receiver, Sender};
use tokio::sync::watch;
use tokio::sync::Mutex as AsyncMutex;
use tokio::{io, time};
use tokio_tun::Tun;
const TIMEOUT: time::Duration = time::Duration::from_secs(1);
const RETRIES: usize = 6;
const MPSC_BUFFER_LEN: usize = 512;
#[derive(Debug, Hash, Eq, PartialEq)]
pub struct AddrTuple {
local_addr: SocketAddrV4,
remote_addr: SocketAddrV4,
}
impl AddrTuple {
fn new(local_addr: SocketAddrV4, remote_addr: SocketAddrV4) -> AddrTuple {
AddrTuple {
local_addr,
remote_addr,
}
}
}
#[derive(Debug)]
struct Shared {
tuples: RwLock<HashMap<AddrTuple, Arc<Sender<Bytes>>>>,
listening: RwLock<HashSet<u16>>,
outgoing: Sender<Bytes>,
ready: Sender<Socket>,
}
pub struct Stack {
shared: Arc<Shared>,
local_ip: Ipv4Addr,
ready: Receiver<Socket>,
}
#[derive(Debug)]
pub enum State {
Idle,
SynSent,
SynReceived,
Established,
}
#[derive(Debug)]
pub enum Mode {
Client,
Server,
}
#[derive(Debug)]
pub struct Socket {
mode: Mode,
shared: Arc<Shared>,
incoming: AsyncMutex<Receiver<Bytes>>,
local_addr: SocketAddrV4,
remote_addr: SocketAddrV4,
seq: AtomicU32,
ack: AtomicU32,
state: State,
closing_tx: watch::Sender<()>,
closing_rx: watch::Receiver<()>,
}
impl Socket {
fn new(
mode: Mode,
shared: Arc<Shared>,
local_addr: SocketAddrV4,
remote_addr: SocketAddrV4,
ack: Option<u32>,
state: State,
) -> (Socket, Sender<Bytes>) {
let (incoming_tx, incoming_rx) = mpsc::channel(MPSC_BUFFER_LEN);
let (closing_tx, closing_rx) = watch::channel(());
(
Socket {
mode,
shared,
incoming: AsyncMutex::new(incoming_rx),
local_addr,
remote_addr,
seq: AtomicU32::new(0),
ack: AtomicU32::new(ack.unwrap_or(0)),
state,
closing_tx,
closing_rx,
},
incoming_tx,
)
}
fn build_tcp_packet(&self, flags: u16, payload: Option<&[u8]>) -> Bytes {
build_tcp_packet(
self.local_addr,
self.remote_addr,
self.seq.load(Ordering::Relaxed),
self.ack.load(Ordering::Relaxed),
flags,
payload,
)
}
pub async fn send(&self, payload: &[u8]) -> Option<()> {
let mut closing = self.closing_rx.clone();
match self.state {
State::Established => {
let buf = self.build_tcp_packet(tcp::TcpFlags::ACK, Some(payload));
self.seq.fetch_add(buf.len() as u32, Ordering::Relaxed);
tokio::select! {
res = self.shared.outgoing.send(buf) => {
res.unwrap();
Some(())
},
_ = closing.changed() => {
None
}
}
}
_ => unreachable!(),
}
}
pub async fn recv(&self, buf: &mut [u8]) -> Option<usize> {
let mut closing = self.closing_rx.clone();
match self.state {
State::Established => {
let mut incoming = self.incoming.lock().await;
tokio::select! {
Some(raw_buf) = incoming.recv() => {
let (_v4_packet, tcp_packet) = parse_ipv4_packet(&raw_buf);
if (tcp_packet.get_flags() & tcp::TcpFlags::RST) != 0 {
info!("Connection {} reset by peer", self);
self.close();
return None;
}
let payload = tcp_packet.payload();
self.ack
.store(tcp_packet.get_sequence().wrapping_add(1), Ordering::Relaxed);
buf[..payload.len()].copy_from_slice(payload);
Some(payload.len())
},
_ = closing.changed() => {
None
}
}
}
_ => unreachable!(),
}
}
pub fn close(&self) {
self.closing_tx.send(()).unwrap();
}
async fn accept(mut self) {
for _ in 0..RETRIES {
match self.state {
State::Idle => {
let buf = self.build_tcp_packet(tcp::TcpFlags::SYN | tcp::TcpFlags::ACK, None);
// ACK set by constructor
self.shared.outgoing.send(buf).await.unwrap();
self.state = State::SynReceived;
info!("Sent SYN + ACK to client");
}
State::SynReceived => {
let res = time::timeout(TIMEOUT, self.incoming.lock().await.recv()).await;
if let Ok(buf) = res {
let buf = buf.unwrap();
let (_v4_packet, tcp_packet) = parse_ipv4_packet(&buf);
if (tcp_packet.get_flags() & tcp::TcpFlags::RST) != 0 {
return;
}
if tcp_packet.get_flags() == tcp::TcpFlags::ACK
&& tcp_packet.get_acknowledgement()
== self.seq.load(Ordering::Relaxed) + 1
{
// found our ACK
self.seq.fetch_add(1, Ordering::Relaxed);
self.state = State::Established;
info!("Connection from {:?} established", self.remote_addr);
let ready = self.shared.ready.clone();
ready.send(self).await.unwrap();
return;
}
} else {
info!("Waiting for client ACK timed out");
self.state = State::Idle;
}
}
_ => unreachable!(),
}
}
}
async fn connect(&mut self) -> Option<()> {
for _ in 0..RETRIES {
match self.state {
State::Idle => {
let buf = self.build_tcp_packet(tcp::TcpFlags::SYN, None);
self.shared.outgoing.send(buf).await.unwrap();
self.state = State::SynSent;
info!("Sent SYN to server");
}
State::SynSent => {
match time::timeout(TIMEOUT, self.incoming.lock().await.recv()).await {
Ok(buf) => {
let buf = buf.unwrap();
let (_v4_packet, tcp_packet) = parse_ipv4_packet(&buf);
if (tcp_packet.get_flags() & tcp::TcpFlags::RST) != 0 {
return None;
}
if tcp_packet.get_flags() == tcp::TcpFlags::SYN | tcp::TcpFlags::ACK
&& tcp_packet.get_acknowledgement()
== self.seq.load(Ordering::Relaxed) + 1
{
// found our SYN + ACK
self.seq.fetch_add(1, Ordering::Relaxed);
self.ack
.store(tcp_packet.get_sequence() + 1, Ordering::Relaxed);
// send ACK to finish handshake
let buf = self.build_tcp_packet(tcp::TcpFlags::ACK, None);
self.shared.outgoing.send(buf).await.unwrap();
self.state = State::Established;
info!("Connection to {:?} established", self.remote_addr);
return Some(());
}
}
Err(_) => {
info!("Waiting for SYN + ACK timed out");
self.state = State::Idle;
}
}
}
_ => unreachable!(),
}
}
None
}
}
impl Drop for Socket {
fn drop(&mut self) {
// dissociates ourself from the dispatch map
assert!(self
.shared
.tuples
.write()
.unwrap()
.remove(&AddrTuple::new(self.local_addr, self.remote_addr))
.is_some());
let buf = self.build_tcp_packet(tcp::TcpFlags::RST, None);
self.shared.outgoing.try_send(buf).unwrap();
self.close();
info!("Fake TCP connection to {} closed", self);
}
}
impl fmt::Display for Socket {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(
f,
"(Fake TCP connection from {} to {})",
self.local_addr, self.remote_addr
)
}
}
impl Stack {
pub fn new(tun: Tun) -> Stack {
let (outgoing_tx, outgoing_rx) = mpsc::channel(MPSC_BUFFER_LEN);
let (ready_tx, ready_rx) = mpsc::channel(MPSC_BUFFER_LEN);
let shared = Arc::new(Shared {
tuples: RwLock::new(HashMap::new()),
outgoing: outgoing_tx,
listening: RwLock::new(HashSet::new()),
ready: ready_tx,
});
let local_ip = tun.destination().unwrap();
tokio::spawn(Stack::dispatch(tun, outgoing_rx, shared.clone()));
Stack {
shared,
local_ip,
ready: ready_rx,
}
}
pub fn listen(&mut self, port: u16) {
assert!(self.shared.listening.write().unwrap().insert(port));
}
pub async fn accept(&mut self) -> Socket {
self.ready.recv().await.unwrap()
}
pub async fn connect(&mut self, addr: SocketAddrV4) -> Option<Socket> {
let mut rng = SmallRng::from_entropy();
let local_port: u16 = rng.gen_range(1024..65535);
let local_addr = SocketAddrV4::new(self.local_ip, local_port);
let tuple = AddrTuple::new(local_addr, addr);
let (mut sock, incoming) = Socket::new(
Mode::Client,
self.shared.clone(),
local_addr,
addr,
None,
State::Idle,
);
{
let mut tuples = self.shared.tuples.write().unwrap();
assert!(tuples.insert(tuple, Arc::new(incoming.clone())).is_none());
}
sock.connect().await.map(|_| sock)
}
async fn dispatch(tun: Tun, mut outgoing: Receiver<Bytes>, shared: Arc<Shared>) {
let (mut tun_r, mut tun_w) = io::split(tun);
loop {
let mut buf = BytesMut::with_capacity(MAX_PACKET_LEN);
tokio::select! {
buf = outgoing.recv() => {
let buf = buf.unwrap();
tun_w.write_all(&buf).await.unwrap();
},
s = tun_r.read_buf(&mut buf) => {
s.unwrap();
let buf = buf.freeze();
if buf[0] >> 4 != 4 {
// not an IPv4 packet
continue;
}
let (ip_packet, tcp_packet) = parse_ipv4_packet(&buf);
let local_addr = SocketAddrV4::new(ip_packet.get_destination(), tcp_packet.get_destination());
let remote_addr = SocketAddrV4::new(ip_packet.get_source(), tcp_packet.get_source());
let tuple = AddrTuple::new(local_addr, remote_addr);
let sender;
{
let tuples = shared.tuples.read().unwrap();
sender = tuples.get(&tuple).cloned();
}
if let Some(c) = sender {
c.send(buf).await.unwrap();
continue;
}
if tcp_packet.get_flags() == tcp::TcpFlags::SYN && shared.listening.read().unwrap().contains(&tcp_packet.get_destination()) {
// SYN seen on listening socket
if tcp_packet.get_sequence() == 0 {
let (sock, incoming) = Socket::new(Mode::Server, shared.clone(), local_addr, remote_addr, Some(tcp_packet.get_sequence() + 1), State::Idle);
assert!(shared.tuples.write().unwrap().insert(tuple, Arc::new(incoming)).is_none());
tokio::spawn(sock.accept());
} else {
trace!("Bad TCP SYN packet from {}, sending RST", remote_addr);
let buf = build_tcp_packet(
local_addr,
remote_addr,
0,
tcp_packet.get_sequence() + 1,
tcp::TcpFlags::RST,
None,
);
shared.outgoing.try_send(buf).unwrap();
}
} else if (tcp_packet.get_flags() & tcp::TcpFlags::RST) == 0 {
info!("Unknown TCP packet from {}, sending RST", remote_addr);
let buf = build_tcp_packet(
local_addr,
remote_addr,
tcp_packet.get_acknowledgement(),
0,
tcp::TcpFlags::RST,
None,
);
shared.outgoing.try_send(buf).unwrap();
}
}
}
}
}
}

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use bytes::{Bytes, BytesMut};
use pnet::packet::{ip, ipv4, tcp};
use std::convert::TryInto;
use std::net::SocketAddrV4;
const IPV4_HEADER_LEN: usize = 20;
const TCP_HEADER_LEN: usize = 20;
pub const MAX_PACKET_LEN: usize = 1500;
pub fn build_tcp_packet(
local_addr: SocketAddrV4,
remote_addr: SocketAddrV4,
seq: u32,
ack: u32,
flags: u16,
payload: Option<&[u8]>,
) -> Bytes {
let wscale = (flags & tcp::TcpFlags::SYN) != 0;
let tcp_total_len = TCP_HEADER_LEN + if wscale {4} else {0} // nop + wscale
+ payload.map_or(0, |payload| payload.len());
let total_len = IPV4_HEADER_LEN + tcp_total_len;
let mut buf = BytesMut::with_capacity(total_len);
buf.resize(total_len, 0);
let mut v4_buf = buf.split_to(IPV4_HEADER_LEN);
let mut tcp_buf = buf.split_to(tcp_total_len);
assert_eq!(0, buf.len());
let mut v4 = ipv4::MutableIpv4Packet::new(&mut v4_buf).unwrap();
v4.set_version(4);
v4.set_header_length(IPV4_HEADER_LEN as u8 / 4);
v4.set_next_level_protocol(ip::IpNextHeaderProtocols::Tcp);
v4.set_ttl(32);
v4.set_source(*local_addr.ip());
v4.set_destination(*remote_addr.ip());
v4.set_total_length(total_len.try_into().unwrap());
v4.set_flags(ipv4::Ipv4Flags::DontFragment);
v4.set_checksum(ipv4::checksum(&v4.to_immutable()));
let mut tcp = tcp::MutableTcpPacket::new(&mut tcp_buf).unwrap();
tcp.set_window(0xffff);
tcp.set_source(local_addr.port());
tcp.set_destination(remote_addr.port());
tcp.set_sequence(seq);
tcp.set_acknowledgement(ack);
tcp.set_flags(flags);
tcp.set_data_offset(TCP_HEADER_LEN as u8 / 4 + if wscale { 1 } else { 0 });
if wscale {
let wscale = tcp::TcpOption::wscale(14);
tcp.set_options(&[tcp::TcpOption::nop(), wscale]);
}
if let Some(payload) = payload {
tcp.set_payload(payload);
}
let checksum = tcp::ipv4_checksum(&tcp.to_immutable(), local_addr.ip(), remote_addr.ip());
tcp.set_checksum(checksum);
v4_buf.unsplit(tcp_buf);
v4_buf.freeze()
}
pub fn parse_ipv4_packet(buf: &Bytes) -> (ipv4::Ipv4Packet, tcp::TcpPacket) {
let v4 = ipv4::Ipv4Packet::new(buf).unwrap();
let tcp = tcp::TcpPacket::new(&buf[IPV4_HEADER_LEN..]).unwrap();
(v4, tcp)
}