Merge branch 'main' of https://github.com/olaservo/inspector

server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@modelcontextprotocol/inspector-server",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "description": "Server-side application for the Model Context Protocol inspector",
   "license": "MIT",
   "author": "Anthropic, PBC (https://anthropic.com)",
@@ -20,16 +20,14 @@
   },
   "devDependencies": {
     "@types/cors": "^2.8.17",
-    "@types/eventsource": "^1.1.15",
     "@types/express": "^4.17.21",
     "@types/ws": "^8.5.12",
     "tsx": "^4.19.0",
     "typescript": "^5.6.2"
   },
   "dependencies": {
-    "@modelcontextprotocol/sdk": "^1.0.3",
+    "@modelcontextprotocol/sdk": "^1.4.1",
     "cors": "^2.8.5",
-    "eventsource": "^2.0.2",
     "express": "^4.21.0",
     "ws": "^8.18.0",
     "zod": "^3.23.8"

server/src/index.ts

@@ -1,29 +1,29 @@
 #!/usr/bin/env node
 
 import cors from "cors";
-import EventSource from "eventsource";
 import { parseArgs } from "node:util";
 import { parse as shellParseArgs } from "shell-quote";
 
-import { SSEClientTransport } from "@modelcontextprotocol/sdk/client/sse.js";
+import {
+  SSEClientTransport,
+  SseError,
+} from "@modelcontextprotocol/sdk/client/sse.js";
 import {
   StdioClientTransport,
   getDefaultEnvironment,
 } from "@modelcontextprotocol/sdk/client/stdio.js";
 import { SSEServerTransport } from "@modelcontextprotocol/sdk/server/sse.js";
 import express from "express";
-import mcpProxy from "./mcpProxy.js";
 import { findActualExecutable } from "spawn-rx";
+import mcpProxy from "./mcpProxy.js";
+
+const SSE_HEADERS_PASSTHROUGH = ["authorization"];
 
 const defaultEnvironment = {
   ...getDefaultEnvironment(),
   ...(process.env.MCP_ENV_VARS ? JSON.parse(process.env.MCP_ENV_VARS) : {}),
 };
 
-// Polyfill EventSource for an SSE client in Node.js
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-(global as any).EventSource = EventSource;
-
 const { values } = parseArgs({
   args: process.argv.slice(2),
   options: {
@@ -37,7 +37,8 @@ app.use(cors());
 
 let webAppTransports: SSEServerTransport[] = [];
 
-const createTransport = async (query: express.Request["query"]) => {
+const createTransport = async (req: express.Request) => {
+  const query = req.query;
   console.log("Query parameters:", query);
 
   const transportType = query.transportType as string;
@@ -65,9 +66,26 @@ const createTransport = async (query: express.Request["query"]) => {
     return transport;
   } else if (transportType === "sse") {
     const url = query.url as string;
-    console.log(`SSE transport: url=${url}`);
+    const headers: HeadersInit = {};
+    for (const key of SSE_HEADERS_PASSTHROUGH) {
+      if (req.headers[key] === undefined) {
+        continue;
+      }
 
-    const transport = new SSEClientTransport(new URL(url));
+      const value = req.headers[key];
+      headers[key] = Array.isArray(value) ? value[value.length - 1] : value;
+    }
+
+    console.log(`SSE transport: url=${url}, headers=${Object.keys(headers)}`);
+
+    const transport = new SSEClientTransport(new URL(url), {
+      eventSourceInit: {
+        fetch: (url, init) => fetch(url, { ...init, headers }),
+      },
+      requestInit: {
+        headers,
+      },
+    });
     await transport.start();
 
     console.log("Connected to SSE transport");
@@ -82,7 +100,21 @@ app.get("/sse", async (req, res) => {
   try {
     console.log("New SSE connection");
 
-    const backingServerTransport = await createTransport(req.query);
+    let backingServerTransport;
+    try {
+      backingServerTransport = await createTransport(req);
+    } catch (error) {
+      if (error instanceof SseError && error.code === 401) {
+        console.error(
+          "Received 401 Unauthorized from MCP server:",
+          error.message,
+        );
+        res.status(401).json(error);
+        return;
+      }
+
+      throw error;
+    }
 
     console.log("Connected MCP client to backing server transport");
 
@@ -109,9 +141,6 @@ app.get("/sse", async (req, res) => {
     mcpProxy({
       transportToClient: webAppTransport,
       transportToServer: backingServerTransport,
-      onerror: (error) => {
-        console.error(error);
-      },
     });
 
     console.log("Set up MCP proxy");

server/src/mcpProxy.ts

@@ -1,23 +1,29 @@
 import { Transport } from "@modelcontextprotocol/sdk/shared/transport.js";
 
+function onClientError(error: Error) {
+  console.error("Error from inspector client:", error);
+}
+
+function onServerError(error: Error) {
+  console.error("Error from MCP server:", error);
+}
+
 export default function mcpProxy({
   transportToClient,
   transportToServer,
-  onerror,
 }: {
   transportToClient: Transport;
   transportToServer: Transport;
-  onerror: (error: Error) => void;
 }) {
   let transportToClientClosed = false;
   let transportToServerClosed = false;
 
   transportToClient.onmessage = (message) => {
-    transportToServer.send(message).catch(onerror);
+    transportToServer.send(message).catch(onServerError);
   };
 
   transportToServer.onmessage = (message) => {
-    transportToClient.send(message).catch(onerror);
+    transportToClient.send(message).catch(onClientError);
   };
 
   transportToClient.onclose = () => {
@@ -26,7 +32,7 @@ export default function mcpProxy({
     }
 
     transportToClientClosed = true;
-    transportToServer.close().catch(onerror);
+    transportToServer.close().catch(onServerError);
   };
 
   transportToServer.onclose = () => {
@@ -34,10 +40,9 @@ export default function mcpProxy({
       return;
     }
     transportToServerClosed = true;
-
-    transportToClient.close().catch(onerror);
+    transportToClient.close().catch(onClientError);
   };
 
-  transportToClient.onerror = onerror;
-  transportToServer.onerror = onerror;
+  transportToClient.onerror = onClientError;
+  transportToServer.onerror = onServerError;
 }