clinicaltrialsgov-mcp-server
Version:
ClinicalTrials.gov Model Context Protocol (MCP) Server that provides a suite of tools for interacting with the official ClinicalTrials.gov v2 API. Enables AI agents and LLMs to programmatically search, retrieve, and analyze clinical trial data.
99 lines (98 loc) • 3.5 kB
JavaScript
/**
* @fileoverview Centralized error handler for the Hono HTTP transport.
* This middleware intercepts errors that occur during request processing,
* standardizes them using the application's ErrorHandler utility, and
* formats them into a consistent JSON-RPC error response.
* @module src/mcp-server/transports/httpErrorHandler
*/
import { BaseErrorCode, McpError } from "../../../types-global/errors.js";
import { ErrorHandler, logger, requestContextService, } from "../../../utils/index.js";
/**
* A centralized error handling middleware for Hono.
* This function is registered with `app.onError()` and will catch any errors
* thrown from preceding middleware or route handlers.
*
* @param err - The error that was thrown.
* @param c - The Hono context object for the request.
* @returns A Response object containing the formatted JSON-RPC error.
*/
export const httpErrorHandler = async (err, c) => {
const context = requestContextService.createRequestContext({
operation: "httpErrorHandler",
path: c.req.path,
method: c.req.method,
});
logger.debug("HTTP error handler invoked.", context);
const handledError = ErrorHandler.handleError(err, {
operation: "httpTransport",
context,
});
let status = 500;
if (handledError instanceof McpError) {
switch (handledError.code) {
case BaseErrorCode.NOT_FOUND:
status = 404;
break;
case BaseErrorCode.UNAUTHORIZED:
status = 401;
break;
case BaseErrorCode.FORBIDDEN:
status = 403;
break;
case BaseErrorCode.VALIDATION_ERROR:
case BaseErrorCode.INVALID_INPUT:
status = 400;
break;
case BaseErrorCode.CONFLICT:
status = 409;
break;
case BaseErrorCode.RATE_LIMITED:
status = 429;
break;
default:
status = 500;
}
}
logger.debug(`Mapping error to HTTP status ${status}.`, {
...context,
status,
errorCode: handledError.code,
});
// Attempt to get the request ID from the body, but don't fail if it's not there or unreadable.
let requestId = null;
// Only attempt to read the body if it hasn't been consumed already.
if (c.req.raw.bodyUsed === false) {
try {
const body = await c.req.json();
requestId = body?.id || null;
logger.debug("Extracted JSON-RPC request ID from body.", {
...context,
jsonRpcId: requestId,
});
}
catch {
logger.warning("Could not parse request body to extract JSON-RPC ID.", context);
// Ignore parsing errors, requestId will remain null
}
}
else {
logger.debug("Request body already consumed, cannot extract JSON-RPC ID.", context);
}
const errorCode = handledError instanceof McpError ? handledError.code : -32603;
c.status(status);
const errorResponse = {
jsonrpc: "2.0",
error: {
code: errorCode,
message: handledError.message,
},
id: requestId,
};
logger.info(`Sending formatted error response for request.`, {
...context,
status,
errorCode,
jsonRpcId: requestId,
});
return c.json(errorResponse);
};