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use std::{
pin::Pin,
task::{Context, Poll},
};
use futures::{Future, Stream};
use mcp_core_fishcode2025::protocol::{
JsonRpcError, JsonRpcMessage, JsonRpcRequest, JsonRpcResponse,
};
use pin_project::pin_project;
use tokio::io::{AsyncBufReadExt, AsyncRead, AsyncWrite, AsyncWriteExt, BufReader};
use tower_service::Service;
mod errors;
pub use errors::{BoxError, RouterError, ServerError, TransportError};
pub mod router;
pub use router::Router;
/// A transport layer that handles JSON-RPC messages over byte
#[pin_project]
pub struct ByteTransport<R, W> {
// Reader is a BufReader on the underlying stream (stdin or similar) buffering
// the underlying data across poll calls, we clear one line (\n) during each
// iteration of poll_next from this buffer
#[pin]
reader: BufReader<R>,
#[pin]
writer: W,
}
impl<R, W> ByteTransport<R, W>
where
R: AsyncRead,
W: AsyncWrite,
{
pub fn new(reader: R, writer: W) -> Self {
Self {
// Default BufReader capacity is 8 * 1024, increase this to 2MB to the file size limit
// allows the buffer to have the capacity to read very large calls
reader: BufReader::with_capacity(2 * 1024 * 1024, reader),
writer,
}
}
}
impl<R, W> Stream for ByteTransport<R, W>
where
R: AsyncRead + Unpin,
W: AsyncWrite + Unpin,
{
type Item = Result<JsonRpcMessage, TransportError>;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let mut this = self.project();
let mut buf = Vec::new();
let mut reader = this.reader.as_mut();
let mut read_future = Box::pin(reader.read_until(b'\n', &mut buf));
match read_future.as_mut().poll(cx) {
Poll::Ready(Ok(0)) => Poll::Ready(None), // EOF
Poll::Ready(Ok(_)) => {
// Convert to UTF-8 string
let line = match String::from_utf8(buf) {
Ok(s) => s,
Err(e) => return Poll::Ready(Some(Err(TransportError::Utf8(e)))),
};
// Log incoming message here before serde conversion to
// track incomplete chunks which are not valid JSON
tracing::info!(json = %line, "incoming message");
// Parse JSON and validate message format
match serde_json::from_str::<serde_json::Value>(&line) {
Ok(value) => {
// Validate basic JSON-RPC structure
if !value.is_object() {
return Poll::Ready(Some(Err(TransportError::InvalidMessage(
"Message must be a JSON object".into(),
))));
}
let obj = value.as_object().unwrap(); // Safe due to check above
// Check jsonrpc version field
if !obj.contains_key("jsonrpc") || obj["jsonrpc"] != "2.0" {
return Poll::Ready(Some(Err(TransportError::InvalidMessage(
"Missing or invalid jsonrpc version".into(),
))));
}
// Now try to parse as proper message
match serde_json::from_value::<JsonRpcMessage>(value) {
Ok(msg) => Poll::Ready(Some(Ok(msg))),
Err(e) => Poll::Ready(Some(Err(TransportError::Json(e)))),
}
}
Err(e) => Poll::Ready(Some(Err(TransportError::Json(e)))),
}
}
Poll::Ready(Err(e)) => Poll::Ready(Some(Err(TransportError::Io(e)))),
Poll::Pending => Poll::Pending,
}
}
}
impl<R, W> ByteTransport<R, W>
where
R: AsyncRead + Unpin,
W: AsyncWrite + Unpin,
{
pub async fn write_message(&mut self, msg: JsonRpcMessage) -> Result<(), std::io::Error> {
let json = serde_json::to_string(&msg)?;
Pin::new(&mut self.writer)
.write_all(json.as_bytes())
.await?;
Pin::new(&mut self.writer).write_all(b"\n").await?;
Pin::new(&mut self.writer).flush().await?;
Ok(())
}
}
/// The main server type that processes incoming requests
pub struct Server<S> {
service: S,
}
impl<S> Server<S>
where
S: Service<JsonRpcRequest, Response = JsonRpcResponse> + Send,
S::Error: Into<BoxError>,
S::Future: Send,
{
pub fn new(service: S) -> Self {
Self { service }
}
// TODO transport trait instead of byte transport if we implement others
pub async fn run<R, W>(self, mut transport: ByteTransport<R, W>) -> Result<(), ServerError>
where
R: AsyncRead + Unpin,
W: AsyncWrite + Unpin,
{
use futures::StreamExt;
let mut service = self.service;
tracing::info!("Server started");
while let Some(msg_result) = transport.next().await {
let _span = tracing::span!(tracing::Level::INFO, "message_processing");
let _enter = _span.enter();
match msg_result {
Ok(msg) => {
match msg {
JsonRpcMessage::Request(request) => {
// Serialize request for logging
let id = request.id;
let request_json = serde_json::to_string(&request)
.unwrap_or_else(|_| "Failed to serialize request".to_string());
tracing::info!(
request_id = ?id,
method = ?request.method,
json = %request_json,
"Received request"
);
// Process the request using our service
let response = match service.call(request).await {
Ok(resp) => resp,
Err(e) => {
let error_msg = e.into().to_string();
tracing::error!(error = %error_msg, "Request processing failed");
JsonRpcResponse {
jsonrpc: "2.0".to_string(),
id,
result: None,
error: Some(mcp_core_fishcode2025::protocol::ErrorData {
code: mcp_core_fishcode2025::protocol::INTERNAL_ERROR,
message: error_msg,
data: None,
}),
}
}
};
// Serialize response for logging
let response_json = serde_json::to_string(&response)
.unwrap_or_else(|_| "Failed to serialize response".to_string());
tracing::info!(
response_id = ?response.id,
json = %response_json,
"Sending response"
);
// Send the response back
if let Err(e) = transport
.write_message(JsonRpcMessage::Response(response))
.await
{
return Err(ServerError::Transport(TransportError::Io(e)));
}
}
JsonRpcMessage::Response(_)
| JsonRpcMessage::Notification(_)
| JsonRpcMessage::Nil
| JsonRpcMessage::Error(_) => {
// Ignore responses, notifications and nil messages for now
continue;
}
}
}
Err(e) => {
// Convert transport error to JSON-RPC error response
let error = match e {
TransportError::Json(_) | TransportError::InvalidMessage(_) => {
mcp_core_fishcode2025::protocol::ErrorData {
code: mcp_core_fishcode2025::protocol::PARSE_ERROR,
message: e.to_string(),
data: None,
}
}
TransportError::Protocol(_) => mcp_core_fishcode2025::protocol::ErrorData {
code: mcp_core_fishcode2025::protocol::INVALID_REQUEST,
message: e.to_string(),
data: None,
},
_ => mcp_core_fishcode2025::protocol::ErrorData {
code: mcp_core_fishcode2025::protocol::INTERNAL_ERROR,
message: e.to_string(),
data: None,
},
};
let error_response = JsonRpcMessage::Error(JsonRpcError {
jsonrpc: "2.0".to_string(),
id: None,
error,
});
if let Err(e) = transport.write_message(error_response).await {
return Err(ServerError::Transport(TransportError::Io(e)));
}
}
}
}
Ok(())
}
}
// Define a specific service implementation that we need for any
// Any router implements this
pub trait BoundedService:
Service<
JsonRpcRequest,
Response = JsonRpcResponse,
Error = BoxError,
Future = Pin<Box<dyn Future<Output = Result<JsonRpcResponse, BoxError>> + Send>>,
> + Send
+ 'static
{
}
// Implement it for any type that meets the bounds
impl<T> BoundedService for T where
T: Service<
JsonRpcRequest,
Response = JsonRpcResponse,
Error = BoxError,
Future = Pin<Box<dyn Future<Output = Result<JsonRpcResponse, BoxError>> + Send>>,
> + Send
+ 'static
{
}