httpmcp_rust/

transport.rs

use crate::context::RequestContext;
use crate::error::{McpError, Result};
use crate::handlers::lifecycle::{handle_initialize, handle_ping};
use crate::jsonrpc::{JsonRpcRequest, JsonRpcResponse};
use crate::protocol::*;
use crate::server::HttpMcpServer;
use actix_web::{
    get, post,
    web::{self, Data},
    HttpRequest, HttpResponse, Responder,
};
use actix_web_lab::sse;
use serde_json::Value;
use std::sync::Arc;

/// Configure actix-web application
pub fn create_app(cfg: &mut web::ServiceConfig, server: Arc<HttpMcpServer>) {
    if server.enable_cors {
        cfg.default_service(web::to(|| async {
            HttpResponse::Ok()
                .insert_header(("Access-Control-Allow-Origin", "*"))
                .insert_header(("Access-Control-Allow-Methods", "GET, POST, OPTIONS"))
                .insert_header(("Access-Control-Allow-Headers", "*"))
                .finish()
        }));
    }

    cfg.app_data(Data::new(server.clone()))
        .service(handle_post)
        .service(handle_get);
}

/// POST /mcp - Handle JSON-RPC requests
#[post("/mcp")]
async fn handle_post(
    req: HttpRequest,
    body: web::Json<JsonRpcRequest>,
    server: Data<Arc<HttpMcpServer>>,
) -> Result<impl Responder> {
    let ctx = create_request_context(&req);

    // Validate OAuth if configured
    if let Some(oauth) = &server.oauth_config {
        oauth.validate_token(&ctx).await?;
    }

    // Validate JSON-RPC request
    body.validate()?;

    // Check if this is a notification (no id field)
    let is_notification = body.id.is_none();

    // Check if client accepts SSE (streaming mode)
    let accept_sse = req
        .headers()
        .get("accept")
        .and_then(|v| v.to_str().ok())
        .map(|s| s.contains("text/event-stream"))
        .unwrap_or(false);

    // Route and execute the request
    let response = route_request(&body, &ctx, &server).await?;

    // Notifications MUST NOT receive a response per JSON-RPC 2.0 spec
    if is_notification {
        tracing::debug!("Notification received ({}), returning 204 No Content", body.method);
        let mut resp = HttpResponse::NoContent();
        if server.enable_cors {
            resp.insert_header(("Access-Control-Allow-Origin", "*"));
        }
        return Ok(resp.finish());
    }

    // For SSE mode, broadcast response and return 202 Accepted
    if accept_sse {
        let subscriber_count = server.response_tx.receiver_count();
        tracing::debug!("Broadcasting response to {} subscribers", subscriber_count);

        // If there are active SSE subscribers, send via broadcast
        if subscriber_count > 0 {
            let _ = server.response_tx.send(response);
            let mut resp = HttpResponse::Accepted();
            if server.enable_cors {
                resp.insert_header(("Access-Control-Allow-Origin", "*"));
            }
            return Ok(resp.finish());
        }

        // If no subscribers, fallback to direct response
        tracing::warn!("No SSE subscribers, falling back to direct HTTP response");
    }

    // For non-SSE mode or fallback, return JSON response directly
    let mut resp = HttpResponse::Ok();
    if server.enable_cors {
        resp.insert_header(("Access-Control-Allow-Origin", "*"));
    }
    Ok(resp.json(response))
}

/// GET /mcp - SSE stream for server-to-client messages
#[get("/mcp")]
async fn handle_get(req: HttpRequest, server: Data<Arc<HttpMcpServer>>) -> Result<impl Responder> {
    let ctx = create_request_context(&req);

    // Validate OAuth if configured
    if let Some(oauth) = &server.oauth_config {
        oauth.validate_token(&ctx).await?;
    }

    // Check for Last-Event-ID header for resumption
    let _last_event_id = req
        .headers()
        .get("Last-Event-ID")
        .and_then(|v| v.to_str().ok())
        .map(|s| s.to_string());

    // Subscribe to response broadcast channel
    let mut rx = server.response_tx.subscribe();

    tracing::debug!("SSE stream connected");

    // Create SSE stream from broadcast channel
    let event_stream = async_stream::stream! {
        loop {
            match rx.recv().await {
                Ok(response) => {
                    if let Ok(json) = serde_json::to_string(&response) {
                        tracing::debug!("Sending response via SSE: {}", json);
                        // Send as "message" event with the JSON-RPC response
                        yield Ok::<_, actix_web::Error>(sse::Event::Data(
                            sse::Data::new(json)
                        ));
                    }
                }
                Err(_) => break,
            }
        }
    };

    Ok(sse::Sse::from_stream(event_stream))
}

/// Route JSON-RPC request to appropriate handler
async fn route_request(
    req: &JsonRpcRequest,
    ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    tracing::debug!("Routing request: method={}", req.method);

    match req.method.as_str() {
        // Lifecycle
        "initialize" => {
            handle_initialize(req, server.server_info.clone(), server.capabilities.clone())
        }
        "ping" => handle_ping(req),

        // Notifications
        "notifications/initialized" => handle_notifications_initialized(req),

        // Resources
        "resources/list" => handle_resources_list(req, ctx, server).await,
        "resources/read" => handle_resources_read(req, ctx, server).await,
        "resources/templates/list" => handle_resources_templates(req, ctx, server).await,
        "resources/subscribe" => handle_resources_subscribe(req, ctx, server).await,

        // Tools
        "tools/list" => handle_tools_list(req, ctx, server).await,
        "tools/call" => handle_tools_call(req, ctx, server).await,

        // Prompts
        "prompts/list" => handle_prompts_list(req, ctx, server).await,
        "prompts/get" => handle_prompts_get(req, ctx, server).await,

        // Logging
        "logging/setLevel" => handle_logging_set_level(req),

        _ => Err(McpError::MethodNotFound(req.method.clone())),
    }
}

// ============================================================================
// Resource Handlers
// ============================================================================

async fn handle_resources_list(
    req: &JsonRpcRequest,
    ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    let params: ResourcesListParams =
        serde_json::from_value(req.params.clone().unwrap_or(Value::Null))
            .unwrap_or(ResourcesListParams { cursor: None });

    // Collect all resources from registered handlers
    let mut all_resources = Vec::new();
    for registered in server.resources.values() {
        let (resources, _) = (registered.list_handler)(params.cursor.clone(), ctx.clone()).await?;
        all_resources.extend(resources);
    }

    let result = ResourcesListResult {
        resources: all_resources,
        next_cursor: None,
    };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

async fn handle_resources_read(
    req: &JsonRpcRequest,
    ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    let params: ResourcesReadParams =
        serde_json::from_value(req.params.clone().unwrap_or(Value::Null))
            .map_err(|e| McpError::InvalidParams(format!("Invalid params: {}", e)))?;

    // Try to find matching resource handler
    let mut contents = Vec::new();
    for registered in server.resources.values() {
        let result = (registered.read_handler)(params.uri.clone(), ctx.clone()).await?;
        contents.extend(result);
    }

    if contents.is_empty() {
        return Err(McpError::ResourceNotFound(params.uri));
    }

    let result = ResourcesReadResult { contents };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

async fn handle_resources_templates(
    req: &JsonRpcRequest,
    _ctx: &RequestContext,
    _server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    // Resource templates are not supported in the new function-based API
    Ok(JsonRpcResponse::success(
        serde_json::json!({ "resourceTemplates": [] }),
        req.id.clone(),
    ))
}

async fn handle_resources_subscribe(
    req: &JsonRpcRequest,
    _ctx: &RequestContext,
    _server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    // Resource subscription is not supported in the new function-based API
    Ok(JsonRpcResponse::success(Value::Null, req.id.clone()))
}

// ============================================================================
// Tool Handlers
// ============================================================================

async fn handle_tools_list(
    req: &JsonRpcRequest,
    _ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    // Collect all registered tools
    let tools: Vec<Tool> = server
        .tools
        .values()
        .map(|registered| registered.meta.clone())
        .collect();

    let result = ToolsListResult {
        tools,
        next_cursor: None,
    };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

async fn handle_tools_call(
    req: &JsonRpcRequest,
    ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    let params: ToolsCallParams = serde_json::from_value(req.params.clone().unwrap_or(Value::Null))
        .map_err(|e| McpError::InvalidParams(format!("Invalid params: {}", e)))?;

    // Find the registered tool
    let registered = server
        .tools
        .get(&params.name)
        .ok_or_else(|| McpError::ToolNotFound(params.name.clone()))?;

    // Call the tool handler
    let result_value =
        (registered.handler)(params.arguments.unwrap_or_default(), ctx.clone()).await?;

    // Convert result to ToolContent
    let content = vec![ToolContent::Text {
        text: result_value.to_string(),
    }];

    let result = ToolsCallResult {
        content,
        is_error: None,
    };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

// ============================================================================
// Prompt Handlers
// ============================================================================

async fn handle_prompts_list(
    req: &JsonRpcRequest,
    _ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    // Collect all registered prompts
    let prompts: Vec<Prompt> = server
        .prompts
        .values()
        .map(|registered| registered.meta.clone())
        .collect();

    let result = PromptsListResult {
        prompts,
        next_cursor: None,
    };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

async fn handle_prompts_get(
    req: &JsonRpcRequest,
    ctx: &RequestContext,
    server: &HttpMcpServer,
) -> Result<JsonRpcResponse> {
    let params: PromptsGetParams =
        serde_json::from_value(req.params.clone().unwrap_or(Value::Null))
            .map_err(|e| McpError::InvalidParams(format!("Invalid params: {}", e)))?;

    // Find the registered prompt
    let registered = server
        .prompts
        .get(&params.name)
        .ok_or_else(|| McpError::PromptNotFound(params.name.clone()))?;

    // Call the prompt handler
    let (description, messages) =
        (registered.handler)(params.name.clone(), params.arguments, ctx.clone()).await?;

    let result = PromptsGetResult {
        description,
        messages,
    };

    Ok(JsonRpcResponse::success(
        serde_json::to_value(result)?,
        req.id.clone(),
    ))
}

// ============================================================================
// Notification Handlers
// ============================================================================

fn handle_notifications_initialized(req: &JsonRpcRequest) -> Result<JsonRpcResponse> {
    tracing::debug!("Client initialized notification received");
    // Return empty object instead of null
    Ok(JsonRpcResponse::success(serde_json::json!({}), req.id.clone()))
}

// ============================================================================
// Logging Handlers
// ============================================================================

fn handle_logging_set_level(req: &JsonRpcRequest) -> Result<JsonRpcResponse> {
    let _params: LoggingSetLevelParams =
        serde_json::from_value(req.params.clone().unwrap_or(Value::Null))
            .map_err(|e| McpError::InvalidParams(format!("Invalid params: {}", e)))?;

    // TODO: Implement actual log level setting
    Ok(JsonRpcResponse::success(serde_json::json!({}), req.id.clone()))
}

// ============================================================================
// Utilities
// ============================================================================

fn create_request_context(req: &HttpRequest) -> RequestContext {
    RequestContext::new(
        req.headers().clone(),
        req.method().to_string(),
        req.path().to_string(),
        req.peer_addr(),
    )
}