mcp_memory/
http.rs

1//! MCP **Streamable HTTP** transport (the 2025-03-26 transport that
2//! superseded the older HTTP+SSE pair).
3//!
4//! * `POST /mcp` — the client sends one JSON-RPC message (or a batch array).
5//!   The reply is delivered as `application/json` by default, or as a one-shot
6//!   `text/event-stream` (SSE) event when the client `Accept`s it. A body of
7//!   only notifications gets `202 Accepted` with no content.
8//! * `GET /mcp` — opens a standalone server→client SSE stream. This server has
9//!   no server-initiated messages, so the stream simply stays open with
10//!   keep-alives; it exists for spec compliance.
11//!
12//! `/` is also wired to the same handlers for convenience. The JSON-RPC
13//! semantics are identical to the stdio and TCP transports — only framing
14//! differs (see [`crate::server::dispatch_http_body`]).
15
16use std::convert::Infallible;
17use std::sync::Arc;
18
19use axum::extract::{DefaultBodyLimit, State};
20use axum::http::{header, HeaderMap, StatusCode};
21use axum::response::sse::{Event, KeepAlive, Sse};
22use axum::response::{IntoResponse, Response};
23use axum::routing::post;
24use axum::{Json, Router};
25use serde_json::json;
26use tokio::net::TcpListener;
27use tracing::{error, info};
28
29use crate::errors::{MCSError, Result};
30use crate::kg::GraphHandle;
31use crate::server;
32
33/// Shared state for the HTTP handlers: the graph plus an optional bearer token
34/// required on every request when present.
35#[derive(Clone)]
36pub struct HttpState {
37    kg: Arc<GraphHandle>,
38    auth_token: Option<Arc<str>>,
39}
40
41/// Build the axum router for the HTTP transport. Exposed so tests can drive it
42/// with `tower::ServiceExt::oneshot` without binding a socket.
43pub fn router(state: HttpState) -> Router {
44    Router::new()
45        .route("/mcp", post(post_handler).get(get_handler))
46        .route("/", post(post_handler).get(get_handler))
47        .layer(DefaultBodyLimit::max(server::MAX_REQUEST_BYTES))
48        .with_state(state)
49}
50
51/// Bind `addr` and serve the HTTP transport until the process is killed.
52///
53/// When `tls_cert` and `tls_key` are both set, the transport is served over TLS
54/// (HTTPS); otherwise it stays plaintext. The caller (`config.rs`) guarantees
55/// the two are set together.
56pub async fn run(
57    addr: &str,
58    kg: Arc<GraphHandle>,
59    auth_token: Option<Arc<str>>,
60    tls_cert: Option<std::path::PathBuf>,
61    tls_key: Option<std::path::PathBuf>,
62) -> Result<()> {
63    let auth = if auth_token.is_some() { "on" } else { "off" };
64    let state = HttpState { kg, auth_token };
65
66    if let (Some(cert), Some(key)) = (tls_cert, tls_key) {
67        let tls = crate::tls::server_config(&cert, &key)
68            .await
69            .map_err(MCSError::IoError)?;
70        let socket_addr = resolve_addr(addr)?;
71        info!("Listening for HTTPS (Streamable) MCP on https://{socket_addr}/mcp (TLS, auth {auth})");
72        axum_server::bind_rustls(socket_addr, tls)
73            .serve(router(state).into_make_service())
74            .await
75            .map_err(MCSError::IoError)?;
76    } else {
77        let listener = TcpListener::bind(addr).await.map_err(MCSError::IoError)?;
78        info!("Listening for HTTP (Streamable) MCP on http://{addr}/mcp (auth {auth})");
79        axum::serve(listener, router(state))
80            .await
81            .map_err(MCSError::IoError)?;
82    }
83    Ok(())
84}
85
86/// Resolve a `host:port` string to a single `SocketAddr` for `axum_server`,
87/// which binds an address rather than an already-bound listener.
88fn resolve_addr(addr: &str) -> Result<std::net::SocketAddr> {
89    use std::net::ToSocketAddrs;
90    addr.to_socket_addrs()
91        .map_err(MCSError::IoError)?
92        .next()
93        .ok_or_else(|| {
94            MCSError::IoError(std::io::Error::new(
95                std::io::ErrorKind::InvalidInput,
96                format!("could not resolve bind address '{addr}'"),
97            ))
98        })
99}
100
101fn wants_sse(headers: &HeaderMap) -> bool {
102    headers
103        .get(header::ACCEPT)
104        .and_then(|v| v.to_str().ok())
105        .is_some_and(|a| a.contains("text/event-stream"))
106}
107
108/// `true` when the request is allowed: either no token is configured, or the
109/// `Authorization` header carries the expected bearer token.
110fn authorized(state: &HttpState, headers: &HeaderMap) -> bool {
111    match state.auth_token {
112        None => true,
113        Some(ref expected) => headers
114            .get(header::AUTHORIZATION)
115            .and_then(|v| v.to_str().ok())
116            .is_some_and(|presented| server::token_matches(presented, expected)),
117    }
118}
119
120async fn post_handler(State(state): State<HttpState>, headers: HeaderMap, body: String) -> Response {
121    if !authorized(&state, &headers) {
122        return (StatusCode::UNAUTHORIZED, "Unauthorized").into_response();
123    }
124    let kg = state.kg;
125    // The dispatch path locks the graph and may perform a blocking fsync, so
126    // run it off the async worker pool (keeps the HTTP reactor responsive).
127    let result = tokio::task::spawn_blocking(move || server::dispatch_http_body(&body, &kg)).await;
128
129    let outcome = match result {
130        Ok(inner) => inner,
131        Err(join_err) => {
132            error!("dispatch task panicked: {join_err}");
133            return (StatusCode::INTERNAL_SERVER_ERROR, "internal error").into_response();
134        }
135    };
136
137    match outcome {
138        // Body held only notifications → nothing to return.
139        Ok(None) => StatusCode::ACCEPTED.into_response(),
140        Ok(Some(value)) => {
141            if wants_sse(&headers) {
142                // One JSON-RPC reply delivered as a single SSE event, then close.
143                let json = serde_json::to_string(&value).unwrap();
144                let stream = futures::stream::once(async move {
145                    Ok::<Event, Infallible>(Event::default().data(json))
146                });
147                Sse::new(stream).into_response()
148            } else {
149                Json(value).into_response()
150            }
151        }
152        Err(e) => {
153            // Malformed JSON body → JSON-RPC parse error.
154            let resp = json!({
155                "jsonrpc": "2.0",
156                "error": { "code": -32700, "message": format!("Parse error: {e}") },
157                "id": null
158            });
159            (StatusCode::BAD_REQUEST, Json(resp)).into_response()
160        }
161    }
162}
163
164async fn get_handler(State(state): State<HttpState>, headers: HeaderMap) -> Response {
165    if !authorized(&state, &headers) {
166        return (StatusCode::UNAUTHORIZED, "Unauthorized").into_response();
167    }
168    // No server-initiated messages: an open, keep-alive'd stream for compliance.
169    let stream = futures::stream::pending::<std::result::Result<Event, Infallible>>();
170    Sse::new(stream)
171        .keep_alive(KeepAlive::default())
172        .into_response()
173}
174
175
mcp_memory/http.rs

mcp_memory/
http.rs
