feat(extension): extract http request part into rmcp extension (#163)

* feat(extension): extract http request part into rmcp extension

* perf(extension): insert extension from one entrypoint

crates/rmcp/src/model/meta.rs

@@ -4,8 +4,8 @@ use serde::{Deserialize, Serialize};
 use serde_json::Value;
 
 use super::{
-    ClientNotification, ClientRequest, Extensions, JsonObject, NumberOrString, ProgressToken,
-    ServerNotification, ServerRequest,
+    ClientNotification, ClientRequest, Extensions, JsonObject, JsonRpcMessage, NumberOrString,
+    ProgressToken, ServerNotification, ServerRequest,
 };
 
 pub trait GetMeta {
@@ -153,3 +153,42 @@ impl DerefMut for Meta {
         &mut self.0
     }
 }
+
+impl<Req, Resp, Noti> JsonRpcMessage<Req, Resp, Noti>
+where
+    Req: GetExtensions,
+    Noti: GetExtensions,
+{
+    pub fn insert_extension<T: Clone + Send + Sync + 'static>(&mut self, value: T) {
+        match self {
+            JsonRpcMessage::Request(json_rpc_request) => {
+                json_rpc_request.request.extensions_mut().insert(value);
+            }
+            JsonRpcMessage::Notification(json_rpc_notification) => {
+                json_rpc_notification
+                    .notification
+                    .extensions_mut()
+                    .insert(value);
+            }
+            JsonRpcMessage::BatchRequest(json_rpc_batch_request_items) => {
+                for item in json_rpc_batch_request_items {
+                    match item {
+                        super::JsonRpcBatchRequestItem::Request(json_rpc_request) => {
+                            json_rpc_request
+                                .request
+                                .extensions_mut()
+                                .insert(value.clone());
+                        }
+                        super::JsonRpcBatchRequestItem::Notification(json_rpc_notification) => {
+                            json_rpc_notification
+                                .notification
+                                .extensions_mut()
+                                .insert(value.clone());
+                        }
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+}

crates/rmcp/src/transport/sse_server.rs

@@ -3,7 +3,7 @@ use std::{collections::HashMap, io, net::SocketAddr, sync::Arc, time::Duration};
 use axum::{
     Json, Router,
     extract::{Query, State},
-    http::StatusCode,
+    http::{StatusCode, request::Parts},
     response::{
         Response,
         sse::{Event, KeepAlive, Sse},
@@ -64,7 +64,8 @@ pub struct PostEventQuery {
 async fn post_event_handler(
     State(app): State<App>,
     Query(PostEventQuery { session_id }): Query<PostEventQuery>,
-    Json(message): Json<ClientJsonRpcMessage>,
+    parts: Parts,
+    Json(mut message): Json<ClientJsonRpcMessage>,
 ) -> Result<StatusCode, StatusCode> {
     tracing::debug!(session_id, ?message, "new client message");
     let tx = {
@@ -73,6 +74,7 @@ async fn post_event_handler(
             .ok_or(StatusCode::NOT_FOUND)?
             .clone()
     };
+    message.insert_extension(parts);
     if tx.send(message).await.is_err() {
         tracing::error!("send message error");
         return Err(StatusCode::GONE);

crates/rmcp/src/transport/streamable_http_server/axum.rs

@@ -3,7 +3,7 @@ use std::{collections::HashMap, io, net::SocketAddr, sync::Arc, time::Duration};
 use axum::{
     Json, Router,
     extract::State,
-    http::{HeaderMap, HeaderValue, StatusCode},
+    http::{HeaderMap, HeaderValue, StatusCode, request::Parts},
     response::{
         IntoResponse, Response,
         sse::{Event, KeepAlive, Sse},
@@ -68,11 +68,11 @@ fn receiver_as_stream(
 
 async fn post_handler(
     State(app): State<App>,
-    header_map: HeaderMap,
-    Json(message): Json<ClientJsonRpcMessage>,
+    parts: Parts,
+    Json(mut message): Json<ClientJsonRpcMessage>,
 ) -> Result<Response, Response> {
     use futures::StreamExt;
-    if let Some(session_id) = header_map.get(HEADER_SESSION_ID) {
+    if let Some(session_id) = parts.headers.get(HEADER_SESSION_ID).cloned() {
         let session_id = session_id
             .to_str()
             .map_err(|e| (StatusCode::BAD_REQUEST, e.to_string()).into_response())?;
@@ -84,6 +84,8 @@ async fn post_handler(
                 .ok_or((StatusCode::NOT_FOUND, "session not found").into_response())?;
             session.handle().clone()
         };
+        // inject request part
+        message.insert_extension(parts);
         match &message {
             ClientJsonRpcMessage::Request(_) | ClientJsonRpcMessage::BatchRequest(_) => {
                 let receiver = handle.establish_request_wise_channel().await.map_err(|e| {
@@ -128,6 +130,8 @@ async fn post_handler(
     } else {
         // expect initialize message
         let session_id = session_id();
+        // inject request part
+        message.insert_extension(parts);
         let (session, transport) =
             super::session::create_session(session_id.clone(), Default::default());
         let Ok(_) = app.transport_tx.send(transport) else {

examples/servers/src/common/counter.rs

@@ -17,6 +17,7 @@ pub struct StructRequest {
 pub struct Counter {
     counter: Arc<Mutex<i32>>,
 }
+
 #[tool(tool_box)]
 impl Counter {
     #[allow(dead_code)]
@@ -194,4 +195,17 @@ impl ServerHandler for Counter {
             resource_templates: Vec::new(),
         })
     }
+
+    async fn initialize(
+        &self,
+        _request: InitializeRequestParam,
+        context: RequestContext<RoleServer>,
+    ) -> Result<InitializeResult, McpError> {
+        if let Some(http_request_part) = context.extensions.get::<axum::http::request::Parts>() {
+            let initialize_headers = &http_request_part.headers;
+            let initialize_uri = &http_request_part.uri;
+            tracing::info!(?initialize_headers, %initialize_uri, "initialize from http server");
+        }
+        Ok(self.get_info())
+    }
 }