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Fix: Fix MCP_PROXY_FULL_ADDRESS base path handling for SSE message endpoint #707

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Fix: Fix MCP_PROXY_FULL_ADDRESS base path handling for SSE message endpoint #707

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6b2497c
fix: fix MCP_PROXY_FULL_ADDRESS compatibility with /message
ronantakizawa Aug 12, 2025
3cc35b5
fix: fix MCP_PROXY_FULL_ADDRESS compatibili
ronantakizawa Aug 12, 2025
415e987
Merge branch 'main' into ronantakizawa/mcpproxyfulladdressmessage
ronantakizawa Aug 12, 2025
a6e7cfe
Merge branch 'main' into ronantakizawa/mcpproxyfulladdressmessage
ronantakizawa Aug 13, 2025
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23 changes: 21 additions & 2 deletions server/src/index.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,25 @@ const sessionToken =
process.env.MCP_PROXY_AUTH_TOKEN || randomBytes(32).toString("hex");
const authDisabled = !!process.env.DANGEROUSLY_OMIT_AUTH;

// Extract base path from MCP_PROXY_FULL_ADDRESS for SSE message endpoint
const getMessagePath = (): string => {
const proxyFullAddress = process.env.MCP_PROXY_FULL_ADDRESS;
if (!proxyFullAddress) {
return "/message";
}
try {
const url = new URL(proxyFullAddress);
// Remove trailing slash and add /message to the pathname
const basePath =
url.pathname === "/" ? "" : url.pathname.replace(/\/$/, "");
return `${basePath}/message`;
} catch {
return "/message";
}
};

const MESSAGE_PATH = getMessagePath();

// Origin validation middleware to prevent DNS rebinding attacks
const originValidationMiddleware = (
req: express.Request,
Expand Down Expand Up @@ -391,7 +410,7 @@ app.get(
throw error;
}

const webAppTransport = new SSEServerTransport("/message", res);
const webAppTransport = new SSEServerTransport(MESSAGE_PATH, res);
console.log("Created client transport");

webAppTransports.set(webAppTransport.sessionId, webAppTransport);
Expand Down Expand Up @@ -469,7 +488,7 @@ app.get(
}

if (serverTransport) {
const webAppTransport = new SSEServerTransport("/message", res);
const webAppTransport = new SSEServerTransport(MESSAGE_PATH, res);
webAppTransports.set(webAppTransport.sessionId, webAppTransport);
console.log("Created client transport");
serverTransports.set(webAppTransport.sessionId, serverTransport!);
Expand Down