Secure a Cloudflare Workers MCP Server with PingOne Advanced Identity Cloud

(function () {
  var frJava = JavaImporter(org.forgerock.json.JsonValue);
  var normalizeUrl = function(url) { return url.replace(/\/$/, '') };

  var mcpServerClientId = 'MCP_SERVER_CLIENT_ID';  // placeholder
  var mcpServerUrl = 'URL_OF_DEPLOYED_MCP_SERVER'; // placeholder

  try {
    var requestedResourceList = requestProperties.requestParams.get('resource');
    var requestedResource = String(requestedResourceList.get(0));

    // Only modify tokens intended for the MCP server
    if (normalizeUrl(requestedResource) === normalizeUrl(mcpServerUrl)) {

      // Explicitly set the MCP server as the audience of this token
      token.setField("aud", mcpServerUrl);

      // Authorize MCP server to exchange this token
      var mayAct = frJava.JsonValue.json(frJava.JsonValue.object());
      mayAct.put('client_id', mcpServerClientId);
      mayAct.put('sub', mcpServerClientId);
      token.setMayAct(mayAct);
    };
  } catch (error) {};
}());

(function () {
  var frJava = JavaImporter(org.forgerock.json.JsonValue);
  var normalizeUrl = function(url) { return url.replace(/\/$/, '') };

  // Only modify MCP server access tokens granted with token exchange
  var grantType = requestProperties.requestParams.get('grant_type');
  if (!grantType || grantType.toString() !== '[urn:ietf:params:oauth:grant-type:token-exchange]') {
    return;
  };

  // Only allow MCP server to call these APIs
  var whitelistedAPIs = [
    'URL_OF_DEPLOYED_API', // placeholder value
  ];

  try {
    var requestedResourceList = requestProperties.requestParams.get('resource');
    var requestedResource = JSON.stringify(requestedResourceList).slice(2, -2);

    for (var i = 0; i < whitelistedAPIs.length; i++) {
      var whitelistedApi = normalizeUrl(whitelistedAPIs[i])
      if (normalizeUrl(requestedResource) === whitelistedApi) {
        // Resulting token will be audienced for the requested & whitelisted API
        accessToken.setField("aud", whitelistedApi);
        break;
      };
    };
  } catch (error) {};
}());