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| 1 | +// SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. |
| 2 | +// SPDX-License-Identifier: Apache-2.0 |
| 3 | + |
| 4 | +//! Edge-authenticated WebSocket tunnel proxy for TUI gateway switching. |
| 5 | +
|
| 6 | +use futures::stream::{SplitSink, SplitStream}; |
| 7 | +use futures::{SinkExt, StreamExt}; |
| 8 | +use miette::{IntoDiagnostic, Result}; |
| 9 | +use std::net::SocketAddr; |
| 10 | +use std::sync::Arc; |
| 11 | +use tokio::io::{AsyncReadExt, AsyncWriteExt}; |
| 12 | +use tokio::net::{TcpListener, TcpStream}; |
| 13 | +use tokio_tungstenite::tungstenite::Message; |
| 14 | +use tokio_tungstenite::tungstenite::client::IntoClientRequest; |
| 15 | +use tokio_tungstenite::tungstenite::http::HeaderValue; |
| 16 | +use tokio_tungstenite::{MaybeTlsStream, WebSocketStream}; |
| 17 | +use tracing::{debug, error, warn}; |
| 18 | + |
| 19 | +pub struct EdgeTunnelProxy { |
| 20 | + pub local_addr: SocketAddr, |
| 21 | +} |
| 22 | + |
| 23 | +#[derive(Clone)] |
| 24 | +struct TunnelConfig { |
| 25 | + ws_url: String, |
| 26 | + edge_token: String, |
| 27 | +} |
| 28 | + |
| 29 | +pub async fn start_tunnel_proxy( |
| 30 | + gateway_endpoint: &str, |
| 31 | + edge_token: &str, |
| 32 | +) -> Result<EdgeTunnelProxy> { |
| 33 | + let listener = TcpListener::bind("127.0.0.1:0").await.into_diagnostic()?; |
| 34 | + let local_addr = listener.local_addr().into_diagnostic()?; |
| 35 | + let ws_url = format!( |
| 36 | + "{}/_ws_tunnel", |
| 37 | + gateway_endpoint |
| 38 | + .replacen("https://", "wss://", 1) |
| 39 | + .replacen("http://", "ws://", 1) |
| 40 | + .trim_end_matches('/') |
| 41 | + ); |
| 42 | + let config = Arc::new(TunnelConfig { |
| 43 | + ws_url, |
| 44 | + edge_token: edge_token.to_string(), |
| 45 | + }); |
| 46 | + |
| 47 | + debug!( |
| 48 | + local_addr = %local_addr, |
| 49 | + gateway = %gateway_endpoint, |
| 50 | + "starting TUI edge tunnel proxy" |
| 51 | + ); |
| 52 | + tokio::spawn(accept_loop(listener, config)); |
| 53 | + Ok(EdgeTunnelProxy { local_addr }) |
| 54 | +} |
| 55 | + |
| 56 | +async fn accept_loop(listener: TcpListener, config: Arc<TunnelConfig>) { |
| 57 | + loop { |
| 58 | + match listener.accept().await { |
| 59 | + Ok((stream, peer)) => { |
| 60 | + let config = Arc::clone(&config); |
| 61 | + tokio::spawn(async move { |
| 62 | + if let Err(err) = handle_connection(stream, &config).await { |
| 63 | + warn!(peer = %peer, error = %err, "TUI edge tunnel connection failed"); |
| 64 | + } |
| 65 | + }); |
| 66 | + } |
| 67 | + Err(err) => { |
| 68 | + error!(error = %err, "failed to accept TUI edge tunnel connection"); |
| 69 | + tokio::time::sleep(std::time::Duration::from_millis(100)).await; |
| 70 | + } |
| 71 | + } |
| 72 | + } |
| 73 | +} |
| 74 | + |
| 75 | +async fn handle_connection(tcp_stream: TcpStream, config: &TunnelConfig) -> Result<()> { |
| 76 | + let ws_stream = open_ws(config).await?; |
| 77 | + let (ws_sink, ws_source) = ws_stream.split(); |
| 78 | + let (tcp_read, tcp_write) = tokio::io::split(tcp_stream); |
| 79 | + |
| 80 | + let mut tcp_to_ws = tokio::spawn(copy_tcp_to_ws(tcp_read, ws_sink)); |
| 81 | + let mut ws_to_tcp = tokio::spawn(copy_ws_to_tcp(ws_source, tcp_write)); |
| 82 | + |
| 83 | + tokio::select! { |
| 84 | + res = &mut tcp_to_ws => { |
| 85 | + if let Err(err) = res { |
| 86 | + debug!(error = %err, "TUI tcp->ws task panicked"); |
| 87 | + } |
| 88 | + ws_to_tcp.abort(); |
| 89 | + } |
| 90 | + res = &mut ws_to_tcp => { |
| 91 | + if let Err(err) = res { |
| 92 | + debug!(error = %err, "TUI ws->tcp task panicked"); |
| 93 | + } |
| 94 | + tcp_to_ws.abort(); |
| 95 | + } |
| 96 | + } |
| 97 | + |
| 98 | + Ok(()) |
| 99 | +} |
| 100 | + |
| 101 | +async fn open_ws(config: &TunnelConfig) -> Result<WebSocketStream<MaybeTlsStream<TcpStream>>> { |
| 102 | + let mut request = (&config.ws_url).into_client_request().into_diagnostic()?; |
| 103 | + let token_val = HeaderValue::from_str(&config.edge_token) |
| 104 | + .map_err(|err| miette::miette!("invalid edge token header value: {err}"))?; |
| 105 | + request |
| 106 | + .headers_mut() |
| 107 | + .insert("Cf-Access-Token", token_val.clone()); |
| 108 | + request |
| 109 | + .headers_mut() |
| 110 | + .insert("Cf-Access-Jwt-Assertion", token_val); |
| 111 | + request.headers_mut().insert( |
| 112 | + "Cookie", |
| 113 | + HeaderValue::from_str(&format!("CF_Authorization={}", config.edge_token)) |
| 114 | + .map_err(|err| miette::miette!("invalid edge token cookie value: {err}"))?, |
| 115 | + ); |
| 116 | + |
| 117 | + let (ws_stream, response) = tokio_tungstenite::connect_async(request) |
| 118 | + .await |
| 119 | + .map_err(|err| miette::miette!("WebSocket connect failed: {err}"))?; |
| 120 | + debug!(status = %response.status(), "TUI edge WebSocket connected"); |
| 121 | + Ok(ws_stream) |
| 122 | +} |
| 123 | + |
| 124 | +async fn copy_tcp_to_ws( |
| 125 | + mut tcp_read: tokio::io::ReadHalf<TcpStream>, |
| 126 | + mut ws_sink: SplitSink<WebSocketStream<MaybeTlsStream<TcpStream>>, Message>, |
| 127 | +) { |
| 128 | + let mut buf = vec![0_u8; 32 * 1024]; |
| 129 | + loop { |
| 130 | + match tcp_read.read(&mut buf).await { |
| 131 | + Ok(0) => { |
| 132 | + let _ = ws_sink.close().await; |
| 133 | + break; |
| 134 | + } |
| 135 | + Ok(n) => { |
| 136 | + if ws_sink |
| 137 | + .send(Message::Binary(buf[..n].to_vec().into())) |
| 138 | + .await |
| 139 | + .is_err() |
| 140 | + { |
| 141 | + break; |
| 142 | + } |
| 143 | + } |
| 144 | + Err(err) => { |
| 145 | + debug!(error = %err, "TUI tcp read error"); |
| 146 | + let _ = ws_sink.close().await; |
| 147 | + break; |
| 148 | + } |
| 149 | + } |
| 150 | + } |
| 151 | +} |
| 152 | + |
| 153 | +async fn copy_ws_to_tcp( |
| 154 | + mut ws_source: SplitStream<WebSocketStream<MaybeTlsStream<TcpStream>>>, |
| 155 | + mut tcp_write: tokio::io::WriteHalf<TcpStream>, |
| 156 | +) { |
| 157 | + while let Some(msg) = ws_source.next().await { |
| 158 | + match msg { |
| 159 | + Ok(Message::Binary(data)) => { |
| 160 | + if tcp_write.write_all(&data).await.is_err() { |
| 161 | + break; |
| 162 | + } |
| 163 | + } |
| 164 | + Ok(Message::Close(_)) => break, |
| 165 | + Ok(Message::Ping(_) | Message::Pong(_) | Message::Text(_) | Message::Frame(_)) => {} |
| 166 | + Err(err) => { |
| 167 | + debug!(error = %err, "TUI WebSocket read error"); |
| 168 | + break; |
| 169 | + } |
| 170 | + } |
| 171 | + } |
| 172 | + let _ = tcp_write.shutdown().await; |
| 173 | +} |
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