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//! VPN plumbing for the stdio interface and the iOS/Android FFI.
//!
//! On desktop platforms, this module runs the IP stack and exposes channels
//! for pushing packets in and pulling packets out. The stdio binary reads
//! from / writes to stdin and stdout, while the iOS and Android apps drive
//! the same channels through `send_pkt` / `recv_pkt` and (on Android) a
//! `vpn_fd` file descriptor. There is no longer any platform-specific
//! system-level packet capture here.
use async_channel::{Receiver, Sender};
use bytes::Bytes;
use ipstack_geph::{IpStack, IpStackConfig};
use std::time::Instant;
use anyctx::AnyCtx;
use anyhow::Context;
use futures_concurrency::future::Race as _;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use crate::{
client::CtxField, litecopy::litecopy, session::open_conn, spoof_dns::fake_dns_respond,
taskpool::add_task,
};
/// Force a particular packet to be sent through VPN mode, regardless of whether VPN mode is on.
pub async fn send_vpn_packet(ctx: &AnyCtx<crate::Config>, bts: Bytes) {
tracing::trace!(
len = bts.len(),
chan_len = ctx.get(VPN_CAPTURE_CHAN).0.len(),
"vpn forcing up"
);
let _ = ctx
.get(VPN_CAPTURE_CHAN)
.0
.send((bts, Instant::now()))
.await;
}
/// Receive a packet from VPN mode, regardless of whether VPN mode is on.
pub async fn recv_vpn_packet(ctx: &AnyCtx<crate::Config>) -> Bytes {
ctx.get(VPN_INJECT_CHAN).1.recv().await.unwrap()
}
static VPN_CAPTURE_CHAN: CtxField<(Sender<(Bytes, Instant)>, Receiver<(Bytes, Instant)>)> =
|_| async_channel::bounded(100);
static VPN_INJECT_CHAN: CtxField<(Sender<Bytes>, Receiver<Bytes>)> =
|_| async_channel::bounded(100);
pub async fn vpn_loop(ctx: &AnyCtx<crate::Config>) -> anyhow::Result<()> {
let (send_captured, recv_captured) = async_channel::bounded(100);
let (send_injected, recv_injected) = async_channel::bounded(100);
let ipstack = IpStack::new(
#[cfg(target_os = "ios")]
IpStackConfig {
mtu: 1450,
tcp_timeout: std::time::Duration::from_secs(3600),
udp_timeout: std::time::Duration::from_secs(600),
},
#[cfg(not(target_os = "ios"))]
IpStackConfig {
mtu: 16384,
tcp_timeout: std::time::Duration::from_secs(3600),
udp_timeout: std::time::Duration::from_secs(600),
},
recv_captured,
send_injected,
);
let _shuffle = {
let ctx = ctx.clone();
geph5_rt::spawn(async move {
let up_loop = async {
loop {
let (bts, time) = match ctx.get(VPN_CAPTURE_CHAN).1.recv().await {
Ok(v) => v,
Err(_) => break,
};
tracing::trace!(
len = bts.len(),
elapsed = debug(time.elapsed()),
packet = display(hex::encode(&bts)),
"vpn shuffling up"
);
if send_captured.send(bts).await.is_err() {
break;
}
}
};
let dn_loop = async {
loop {
let bts = match recv_injected.recv().await {
Ok(v) => v,
Err(_) => break,
};
tracing::trace!(len = bts.len(), "vpn shuffling down");
if ctx.get(VPN_INJECT_CHAN).0.send(bts).await.is_err() {
break;
}
}
};
(up_loop, dn_loop).race().await
})
};
loop {
let captured = ipstack
.accept()
.await
.context("could not accept from ipstack")?;
match captured {
ipstack_geph::stream::IpStackStream::Tcp(captured) => {
let peer_addr = captured.peer_addr();
tracing::trace!(
local_addr = display(captured.local_addr()),
peer_addr = display(peer_addr),
"captured a TCP"
);
let ctx_clone = ctx.clone();
let task = geph5_rt::spawn(async move {
let mut captured = captured;
let tunneled = match open_conn(&ctx_clone, "tcp", &peer_addr.to_string()).await {
Ok(tunneled) => tunneled,
Err(err) => {
// The exit reports the dial error (e.g. "Connection
// refused (os error 111)" vs "Network unreachable").
// If the destination actively refused us, RST so the
// app fails fast with "connection refused". Otherwise
// (unreachable/timeout) just drop the stream, leaving
// the SYN unanswered so the app's Happy Eyeballs can
// fall back to another address (e.g. IPv4 when this
// exit can't reach the IPv6 destination).
if format!("{err:#}").contains("os error 111") {
captured.reset();
}
return Err(err);
}
};
tracing::trace!(peer_addr = display(peer_addr), "dialed through VPN");
let (read_tunneled, write_tunneled) = tokio::io::split(tunneled);
let (read_captured, write_captured) = tokio::io::split(captured);
(
litecopy(read_tunneled, write_captured),
litecopy(read_captured, write_tunneled),
)
.race()
.await?;
anyhow::Ok(())
});
if let Some(task_limit) = ctx.init().task_limit {
add_task(task_limit, task);
} else {
task.detach();
}
}
ipstack_geph::stream::IpStackStream::Udp(captured) => {
let peer_addr = captured.peer_addr();
tracing::trace!(
local_addr = display(captured.local_addr()),
peer_addr = display(peer_addr),
"captured a UDP"
);
let peer_addr = if captured.peer_addr().port() == 53 {
if captured.peer_addr().is_ipv6() {
"[2606:4700:4700::1111]:53".parse()?
} else {
"1.1.1.1:53".parse()?
}
} else {
peer_addr
};
let ctx_clone = ctx.clone();
let task = geph5_rt::spawn(async move {
if peer_addr.port() == 53 && ctx_clone.init().spoof_dns {
// fakedns handling
loop {
let pkt = captured.recv().await?;
captured.send(&fake_dns_respond(&ctx_clone, &pkt)?).await?;
}
} else {
let tunneled = open_conn(&ctx_clone, "udp", &peer_addr.to_string()).await?;
let (mut read_tunneled, mut write_tunneled) = tokio::io::split(tunneled);
let up_loop = async {
loop {
let to_up = captured.recv().await?;
write_tunneled
.write_all(&(to_up.len() as u16).to_le_bytes())
.await?;
write_tunneled.write_all(&to_up).await?;
write_tunneled.flush().await?;
}
#[allow(unreachable_code)]
anyhow::Ok(())
};
let dn_loop = async {
loop {
let mut len_buf = [0u8; 2];
read_tunneled.read_exact(&mut len_buf).await?;
let len = u16::from_le_bytes(len_buf) as usize;
let mut buf = vec![0u8; len];
read_tunneled.read_exact(&mut buf).await?;
captured.send(&buf).await?;
}
#[allow(unreachable_code)]
anyhow::Ok(())
};
(up_loop, dn_loop).race().await
}
});
if let Some(task_limit) = ctx.init().task_limit {
add_task(task_limit, task);
} else {
task.detach();
}
}
ipstack_geph::stream::IpStackStream::UnknownTransport(_) => {
// tracing::warn!("captured an UnknownTransport")
}
ipstack_geph::stream::IpStackStream::UnknownNetwork(_) => {
tracing::warn!("captured an UnknownNetwork")
}
}
}
}