Add tcp reverse tunneling

src/tunnel/server.rs

@@ -1,3 +1,5 @@
+use ahash::{HashMap, HashMapExt};
+use futures_util::StreamExt;
 use std::cmp::min;
 use std::ops::{Deref, Not};
 use std::pin::Pin;
@@ -10,10 +12,13 @@ use hyper::server::conn::Http;
 use hyper::service::service_fn;
 use hyper::{http, Body, Request, Response, StatusCode};
 use jsonwebtoken::TokenData;
+use once_cell::sync::Lazy;
+use parking_lot::Mutex;
 
 use tokio::io::{AsyncRead, AsyncWrite};
 use tokio::net::TcpListener;
 use tokio::sync::oneshot;
+use tokio_stream::wrappers::TcpListenerStream;
 use tracing::{error, info, span, warn, Instrument, Level, Span};
 use url::Host;
 
@@ -63,7 +68,7 @@ async fn from_query(
                 Box::pin(cnx),
             ))
         }
-        LocalProtocol::Tcp { .. } => {
+        LocalProtocol::Tcp => {
             let host = Host::parse(&jwt.claims.r)?;
             let port = jwt.claims.rp;
             let (rx, tx) = tcp::connect(&host, port, &server_config.socket_so_mark, Duration::from_secs(10))
@@ -72,6 +77,26 @@ async fn from_query(
 
             Ok((jwt.claims.p, host, port, Box::pin(rx), Box::pin(tx)))
         }
+        LocalProtocol::ReverseTcp => {
+            #[allow(clippy::type_complexity)]
+            static REVERSE: Lazy<Mutex<HashMap<(Host<String>, u16), TcpListenerStream>>> =
+                Lazy::new(|| Mutex::new(HashMap::with_capacity(0)));
+
+            let local_srv = (Host::parse(&jwt.claims.r)?, jwt.claims.rp);
+            let listening_server = REVERSE.lock().remove(&local_srv);
+            let mut listening_server = if let Some(listening_server) = listening_server {
+                listening_server
+            } else {
+                let bind = format!("{}:{}", local_srv.0, local_srv.1);
+                tcp::run_server(bind.parse()?).await?
+            };
+
+            let tcp = listening_server.next().await.unwrap()?;
+            let (local_rx, local_tx) = tokio::io::split(tcp);
+            REVERSE.lock().insert(local_srv.clone(), listening_server);
+
+            Ok((jwt.claims.p, local_srv.0, local_srv.1, Box::pin(local_rx), Box::pin(local_tx)))
+        }
         _ => Err(anyhow::anyhow!("Invalid upgrade request")),
     }
 }