codive-relay 0.1.0

Relay server for secure tunneling
Documentation 
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//! HTTP proxy handler that routes requests to tunnels

use axum::{
    body::Body,
    extract::State,
    http::{Request, Response, StatusCode},
    response::IntoResponse,
};
use base64::Engine;
use bytes::Bytes;
use std::sync::Arc;
use std::time::Duration;
use tokio_stream::wrappers::ReceiverStream;
use tracing::{debug, info, warn};

use crate::state::RelayState;
use crate::tunnel::WsMessage;

/// Check if this is an SSE request
fn is_sse_request(request: &Request<Body>) -> bool {
    // Check Accept header
    if let Some(accept) = request.headers().get("accept") {
        if let Ok(accept_str) = accept.to_str() {
            if accept_str.contains("text/event-stream") {
                return true;
            }
        }
    }

    // Check path pattern (common SSE endpoint patterns)
    let path = request.uri().path();
    path.ends_with("/events") || path.contains("/events/") || path.ends_with("/stream")
}

/// Proxy handler that routes HTTP requests to the appropriate tunnel
pub async fn proxy_handler(
    State(state): State<Arc<RelayState>>,
    request: Request<Body>,
) -> impl IntoResponse {
    // Extract host from request headers
    let host = request
        .headers()
        .get(axum::http::header::HOST)
        .and_then(|v| v.to_str().ok())
        .unwrap_or("");

    // Extract tunnel_id from subdomain
    // Host format: {tunnel_id}.relay.example.com
    let tunnel_id = match extract_tunnel_id(host, &state.config.base_domain) {
        Some(id) => id,
        None => {
            return (
                StatusCode::NOT_FOUND,
                format!("No tunnel found for host: {}", host),
            )
                .into_response();
        }
    };

    // Look up the tunnel
    let tunnel = match state.get_tunnel(&tunnel_id) {
        Some(t) => t,
        None => {
            return (
                StatusCode::BAD_GATEWAY,
                format!("Tunnel '{}' is not connected", tunnel_id),
            )
                .into_response();
        }
    };

    // Check if this is an SSE request
    let is_sse = is_sse_request(&request);

    info!(
        tunnel_id = %tunnel_id,
        method = %request.method(),
        uri = %request.uri(),
        is_sse = %is_sse,
        "Proxying request"
    );

    // Generate request ID
    let request_id = uuid::Uuid::new_v4().to_string();

    // Convert HTTP request to tunnel message
    let method = request.method().to_string();
    let path = request.uri().path().to_string();
    let query = request.uri().query().map(|s| s.to_string());

    let mut headers = std::collections::HashMap::new();
    for (name, value) in request.headers() {
        if let Ok(v) = value.to_str() {
            headers.insert(name.to_string(), v.to_string());
        }
    }

    // Read body
    let body_bytes = match axum::body::to_bytes(request.into_body(), 10 * 1024 * 1024).await {
        Ok(bytes) => bytes,
        Err(e) => {
            warn!(error = %e, "Failed to read request body");
            return (StatusCode::BAD_REQUEST, "Failed to read request body").into_response();
        }
    };

    let body = if body_bytes.is_empty() {
        None
    } else {
        Some(base64::engine::general_purpose::STANDARD.encode(&body_bytes))
    };

    // Create the data message
    let data_msg = codive_tunnel::DataMessage::HttpRequest {
        request_id: request_id.clone(),
        client_id: "proxy".to_string(),
        method,
        path,
        query,
        headers,
        body,
    };

    // Serialize the request
    let msg_bytes = serde_json::to_vec(&data_msg).unwrap();
    let wire_msg = codive_tunnel::WireMessage::encode_encrypted(
        codive_tunnel::message_type::ENCRYPTED_REQUEST,
        msg_bytes,
    );

    // IMPORTANT: Register pending request BEFORE sending to avoid race condition
    // The tunnel client might respond before we're listening otherwise
    enum ResponseReceiver {
        Regular(tokio::sync::oneshot::Receiver<codive_tunnel::DataMessage>),
        Streaming(tokio::sync::mpsc::Receiver<codive_tunnel::DataMessage>),
    }

    let response_rx = if is_sse {
        ResponseReceiver::Streaming(tunnel.register_streaming_request(request_id.clone()))
    } else {
        ResponseReceiver::Regular(tunnel.register_request(request_id.clone()))
    };

    debug!(
        request_id = %request_id,
        tunnel_id = %tunnel_id,
        is_sse = is_sse,
        "Sending request to tunnel"
    );

    if tunnel.ws_sender.send(WsMessage::Binary(wire_msg)).await.is_err() {
        tunnel.pending_requests.remove(&request_id);
        return (StatusCode::BAD_GATEWAY, "Tunnel connection lost").into_response();
    }

    debug!(
        request_id = %request_id,
        "Request sent, waiting for response"
    );

    // Handle SSE vs regular requests differently
    match response_rx {
        ResponseReceiver::Streaming(rx) => {
            handle_sse_response(tunnel, request_id, rx).await
        }
        ResponseReceiver::Regular(rx) => {
            handle_regular_response(tunnel, request_id, rx).await
        }
    }
}

/// Handle regular (non-streaming) HTTP response
async fn handle_regular_response(
    tunnel: Arc<crate::tunnel::TunnelConnection>,
    request_id: String,
    response_rx: tokio::sync::oneshot::Receiver<codive_tunnel::DataMessage>,
) -> Response<Body> {
    // Wait for response with timeout
    let timeout = Duration::from_secs(30);
    match tokio::time::timeout(timeout, response_rx).await {
        Ok(Ok(response_msg)) => {
            // Convert tunnel response to HTTP response
            build_http_response(response_msg)
        }
        Ok(Err(_)) => {
            // Channel closed - tunnel disconnected
            (StatusCode::BAD_GATEWAY, "Tunnel disconnected").into_response()
        }
        Err(_) => {
            // Timeout
            tunnel.pending_requests.remove(&request_id);
            (StatusCode::GATEWAY_TIMEOUT, "Request timed out").into_response()
        }
    }
}

/// Handle SSE streaming response
async fn handle_sse_response(
    tunnel: Arc<crate::tunnel::TunnelConnection>,
    request_id: String,
    mut response_rx: tokio::sync::mpsc::Receiver<codive_tunnel::DataMessage>,
) -> Response<Body> {
    // Wait for the initial response with headers
    let timeout = Duration::from_secs(30);
    let initial_response = match tokio::time::timeout(timeout, response_rx.recv()).await {
        Ok(Some(msg)) => msg,
        Ok(None) => {
            tunnel.complete_streaming_request(&request_id);
            return (StatusCode::BAD_GATEWAY, "Tunnel disconnected").into_response();
        }
        Err(_) => {
            tunnel.complete_streaming_request(&request_id);
            return (StatusCode::GATEWAY_TIMEOUT, "Request timed out").into_response();
        }
    };

    // Extract initial response headers
    let (status, initial_headers, initial_body) = match initial_response {
        codive_tunnel::DataMessage::HttpResponse {
            status,
            headers,
            body,
            streaming,
            ..
        } => {
            if !streaming {
                // Not actually a streaming response, handle as regular
                tunnel.complete_streaming_request(&request_id);
                let response_msg = codive_tunnel::DataMessage::HttpResponse {
                    request_id: request_id.clone(),
                    status,
                    headers,
                    body,
                    streaming: false,
                };
                return build_http_response(response_msg);
            }
            (status, headers, body)
        }
        codive_tunnel::DataMessage::RequestError { message, .. } => {
            tunnel.complete_streaming_request(&request_id);
            return Response::builder()
                .status(StatusCode::BAD_GATEWAY)
                .body(Body::from(message))
                .unwrap();
        }
        _ => {
            tunnel.complete_streaming_request(&request_id);
            return (StatusCode::INTERNAL_SERVER_ERROR, "Unexpected response type").into_response();
        }
    };

    debug!(
        request_id = %request_id,
        status = %status,
        "Starting SSE stream"
    );

    // Create a channel for the streaming body
    let (body_tx, body_rx) = tokio::sync::mpsc::channel::<Result<Bytes, std::io::Error>>(100);

    // Send initial body chunk if present
    if let Some(b64_body) = initial_body {
        if let Ok(bytes) = base64::engine::general_purpose::STANDARD.decode(&b64_body) {
            let _ = body_tx.send(Ok(Bytes::from(bytes))).await;
        }
    }

    // Spawn task to forward chunks
    let req_id = request_id.clone();
    tokio::spawn(async move {
        while let Some(msg) = response_rx.recv().await {
            match msg {
                codive_tunnel::DataMessage::HttpResponseChunk {
                    chunk,
                    is_final,
                    ..
                } => {
                    // Decode and forward chunk
                    if let Ok(bytes) = base64::engine::general_purpose::STANDARD.decode(&chunk) {
                        if body_tx.send(Ok(Bytes::from(bytes))).await.is_err() {
                            debug!(request_id = %req_id, "Client disconnected");
                            break;
                        }
                    }

                    if is_final {
                        debug!(request_id = %req_id, "SSE stream completed");
                        break;
                    }
                }
                codive_tunnel::DataMessage::RequestError { message, .. } => {
                    warn!(request_id = %req_id, error = %message, "SSE stream error");
                    break;
                }
                _ => {
                    // Ignore other message types in streaming context
                }
            }
        }
        // Channel will be dropped here, ending the stream
    });

    // Build response with streaming body
    let status = StatusCode::from_u16(status).unwrap_or(StatusCode::OK);
    let mut response = Response::builder().status(status);

    for (name, value) in initial_headers {
        response = response.header(name, value);
    }

    // Use ReceiverStream to convert mpsc receiver to stream
    let body_stream = ReceiverStream::new(body_rx);
    let body = Body::from_stream(body_stream);

    response.body(body).unwrap_or_else(|_| {
        Response::builder()
            .status(StatusCode::INTERNAL_SERVER_ERROR)
            .body(Body::from("Internal error"))
            .unwrap()
    })
}

/// Extract tunnel ID from the host header
fn extract_tunnel_id(host: &str, base_domain: &str) -> Option<String> {
    // Remove port if present
    let host = host.split(':').next().unwrap_or(host);
    let base = base_domain.split(':').next().unwrap_or(base_domain);

    // Check if host ends with base domain
    if let Some(prefix) = host.strip_suffix(base) {
        // Remove trailing dot
        let prefix = prefix.strip_suffix('.').unwrap_or(prefix);
        if !prefix.is_empty() {
            return Some(prefix.to_string());
        }
    }

    // For development: if host matches tunnel_id.localhost pattern
    if let Some(tunnel_id) = host.strip_suffix(".localhost") {
        return Some(tunnel_id.to_string());
    }

    None
}

/// Build an HTTP response from a tunnel response message
fn build_http_response(msg: codive_tunnel::DataMessage) -> Response<Body> {
    match msg {
        codive_tunnel::DataMessage::HttpResponse {
            status,
            headers,
            body,
            ..
        } => {
            let status = StatusCode::from_u16(status).unwrap_or(StatusCode::INTERNAL_SERVER_ERROR);

            let mut response = Response::builder().status(status);

            for (name, value) in headers {
                response = response.header(name, value);
            }

            let body = if let Some(b64_body) = body {
                match base64::engine::general_purpose::STANDARD.decode(&b64_body) {
                    Ok(bytes) => Body::from(bytes),
                    Err(_) => Body::from(b64_body), // Fallback to raw if not base64
                }
            } else {
                Body::empty()
            };

            response.body(body).unwrap_or_else(|_| {
                Response::builder()
                    .status(StatusCode::INTERNAL_SERVER_ERROR)
                    .body(Body::from("Internal error"))
                    .unwrap()
            })
        }
        codive_tunnel::DataMessage::RequestError { message, .. } => Response::builder()
            .status(StatusCode::BAD_GATEWAY)
            .body(Body::from(message))
            .unwrap(),
        _ => Response::builder()
            .status(StatusCode::INTERNAL_SERVER_ERROR)
            .body(Body::from("Unexpected response type"))
            .unwrap(),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_extract_tunnel_id() {
        assert_eq!(
            extract_tunnel_id("abc123.relay.example.com", "relay.example.com"),
            Some("abc123".to_string())
        );

        assert_eq!(
            extract_tunnel_id("abc123.relay.example.com:3001", "relay.example.com:3001"),
            Some("abc123".to_string())
        );

        assert_eq!(
            extract_tunnel_id("abc123.localhost", "localhost"),
            Some("abc123".to_string())
        );

        assert_eq!(
            extract_tunnel_id("relay.example.com", "relay.example.com"),
            None
        );
    }
}