feat: add passthrough headers support for OpenAPI client and MCP protocol (#345)

src/services/mcpService.ts

@@ -18,6 +18,7 @@ import { getGroup } from './sseService.js';
 import { getServersInGroup, getServerConfigInGroup } from './groupService.js';
 import { saveToolsAsVectorEmbeddings, searchToolsByVector } from './vectorSearchService.js';
 import { OpenAPIClient } from '../clients/openapi.js';
+import { RequestContextService } from './requestContextService.js';
 import { getDataService } from './services.js';
 import { getServerDao, ServerConfigWithName } from '../dao/index.js';
 
@@ -403,6 +404,7 @@ export const initializeClientsFromSettings = async (
         prompts: [],
         createTime: Date.now(),
         enabled: conf.enabled === undefined ? true : conf.enabled,
+        config: conf, // Store reference to original config for OpenAPI passthrough headers
       };
       serverInfos.push(serverInfo);
 
@@ -487,6 +489,7 @@ export const initializeClientsFromSettings = async (
       transport,
       options: requestOptions,
       createTime: Date.now(),
+      config: conf, // Store reference to original config
     };
     serverInfos.push(serverInfo);
 
@@ -1036,7 +1039,34 @@ export const handleCallToolRequest = async (request: any, extra: any) => {
           ? toolName.replace(`${targetServerInfo.name}-`, '')
           : toolName;
 
-        const result = await openApiClient.callTool(cleanToolName, finalArgs);
+        // Extract passthrough headers from extra or request context
+        let passthroughHeaders: Record<string, string> | undefined;
+        let requestHeaders: Record<string, string | string[] | undefined> | null = null;
+
+        // Try to get headers from extra parameter first (if available)
+        if (extra?.headers) {
+          requestHeaders = extra.headers;
+        } else {
+          // Fallback to request context service
+          const requestContextService = RequestContextService.getInstance();
+          requestHeaders = requestContextService.getHeaders();
+        }
+
+        if (requestHeaders && targetServerInfo.config?.openapi?.passthroughHeaders) {
+          passthroughHeaders = {};
+          for (const headerName of targetServerInfo.config.openapi.passthroughHeaders) {
+            // Handle different header name cases (Express normalizes headers to lowercase)
+            const headerValue =
+              requestHeaders[headerName] || requestHeaders[headerName.toLowerCase()];
+            if (headerValue) {
+              passthroughHeaders[headerName] = Array.isArray(headerValue)
+                ? headerValue[0]
+                : String(headerValue);
+            }
+          }
+        }
+
+        const result = await openApiClient.callTool(cleanToolName, finalArgs, passthroughHeaders);
 
         console.log(`OpenAPI tool invocation result: ${JSON.stringify(result)}`);
         return {
@@ -1099,7 +1129,38 @@ export const handleCallToolRequest = async (request: any, extra: any) => {
         `Invoking OpenAPI tool '${cleanToolName}' on server '${serverInfo.name}' with arguments: ${JSON.stringify(request.params.arguments)}`,
       );
 
-      const result = await openApiClient.callTool(cleanToolName, request.params.arguments || {});
+      // Extract passthrough headers from extra or request context
+      let passthroughHeaders: Record<string, string> | undefined;
+      let requestHeaders: Record<string, string | string[] | undefined> | null = null;
+
+      // Try to get headers from extra parameter first (if available)
+      if (extra?.headers) {
+        requestHeaders = extra.headers;
+      } else {
+        // Fallback to request context service
+        const requestContextService = RequestContextService.getInstance();
+        requestHeaders = requestContextService.getHeaders();
+      }
+
+      if (requestHeaders && serverInfo.config?.openapi?.passthroughHeaders) {
+        passthroughHeaders = {};
+        for (const headerName of serverInfo.config.openapi.passthroughHeaders) {
+          // Handle different header name cases (Express normalizes headers to lowercase)
+          const headerValue =
+            requestHeaders[headerName] || requestHeaders[headerName.toLowerCase()];
+          if (headerValue) {
+            passthroughHeaders[headerName] = Array.isArray(headerValue)
+              ? headerValue[0]
+              : String(headerValue);
+          }
+        }
+      }
+
+      const result = await openApiClient.callTool(
+        cleanToolName,
+        request.params.arguments || {},
+        passthroughHeaders,
+      );
 
       console.log(`OpenAPI tool invocation result: ${JSON.stringify(result)}`);
       return {

src/services/requestContextService.ts

@@ -0,0 +1,105 @@
+import { Request } from 'express';
+
+/**
+ * Request context interface for MCP request handling
+ */
+export interface RequestContext {
+  headers: Record<string, string | string[] | undefined>;
+  sessionId?: string;
+  userAgent?: string;
+  remoteAddress?: string;
+}
+
+/**
+ * Service for managing request context during MCP request processing
+ * This allows MCP request handlers to access HTTP headers and other request metadata
+ */
+export class RequestContextService {
+  private static instance: RequestContextService;
+  private requestContext: RequestContext | null = null;
+
+  private constructor() {}
+
+  public static getInstance(): RequestContextService {
+    if (!RequestContextService.instance) {
+      RequestContextService.instance = new RequestContextService();
+    }
+    return RequestContextService.instance;
+  }
+
+  /**
+   * Set the current request context from Express request
+   */
+  public setRequestContext(req: Request): void {
+    this.requestContext = {
+      headers: req.headers,
+      sessionId: (req.headers['mcp-session-id'] as string) || undefined,
+      userAgent: req.headers['user-agent'] as string,
+      remoteAddress: req.ip || req.socket?.remoteAddress,
+    };
+  }
+
+  /**
+   * Set request context from custom data
+   */
+  public setCustomRequestContext(context: RequestContext): void {
+    this.requestContext = context;
+  }
+
+  /**
+   * Get the current request context
+   */
+  public getRequestContext(): RequestContext | null {
+    return this.requestContext;
+  }
+
+  /**
+   * Get headers from the current request context
+   */
+  public getHeaders(): Record<string, string | string[] | undefined> | null {
+    return this.requestContext?.headers || null;
+  }
+
+  /**
+   * Get a specific header value (case-insensitive)
+   */
+  public getHeader(name: string): string | string[] | undefined {
+    if (!this.requestContext?.headers) {
+      return undefined;
+    }
+
+    // Try exact match first
+    if (this.requestContext.headers[name]) {
+      return this.requestContext.headers[name];
+    }
+
+    // Try lowercase match (Express normalizes headers to lowercase)
+    const lowerName = name.toLowerCase();
+    if (this.requestContext.headers[lowerName]) {
+      return this.requestContext.headers[lowerName];
+    }
+
+    // Try case-insensitive search
+    for (const [key, value] of Object.entries(this.requestContext.headers)) {
+      if (key.toLowerCase() === lowerName) {
+        return value;
+      }
+    }
+
+    return undefined;
+  }
+
+  /**
+   * Clear the current request context
+   */
+  public clearRequestContext(): void {
+    this.requestContext = null;
+  }
+
+  /**
+   * Get session ID from current request context
+   */
+  public getSessionId(): string | undefined {
+    return this.requestContext?.sessionId;
+  }
+}

src/services/sseService.ts

@@ -8,6 +8,7 @@ import { deleteMcpServer, getMcpServer } from './mcpService.js';
 import { loadSettings } from '../config/index.js';
 import config from '../config/index.js';
 import { UserContextService } from './userContextService.js';
+import { RequestContextService } from './requestContextService.js';
 
 const transports: { [sessionId: string]: { transport: Transport; group: string } } = {};
 
@@ -131,7 +132,16 @@ export const handleSseMessage = async (req: Request, res: Response): Promise<voi
     `Received message for sessionId: ${sessionId} in group: ${group}${username ? ` for user: ${username}` : ''}`,
   );
 
-  await (transport as SSEServerTransport).handlePostMessage(req, res);
+  // Set request context for MCP handlers to access HTTP headers
+  const requestContextService = RequestContextService.getInstance();
+  requestContextService.setRequestContext(req);
+
+  try {
+    await (transport as SSEServerTransport).handlePostMessage(req, res);
+  } finally {
+    // Clean up request context after handling
+    requestContextService.clearRequestContext();
+  }
 };
 
 export const handleMcpPostRequest = async (req: Request, res: Response): Promise<void> => {
@@ -202,7 +212,17 @@ export const handleMcpPostRequest = async (req: Request, res: Response): Promise
   }
 
   console.log(`Handling request using transport with type ${transport.constructor.name}`);
-  await transport.handleRequest(req, res, req.body);
+
+  // Set request context for MCP handlers to access HTTP headers
+  const requestContextService = RequestContextService.getInstance();
+  requestContextService.setRequestContext(req);
+
+  try {
+    await transport.handleRequest(req, res, req.body);
+  } finally {
+    // Clean up request context after handling
+    requestContextService.clearRequestContext();
+  }
 };
 
 export const handleMcpOtherRequest = async (req: Request, res: Response) => {