weseek__growi/packages/app/src/server/util/rate-limiter.ts

import {
  defaultConfig, defaultConfigWithRegExp, IApiRateLimitEndpointMap,
} from '^/config/rate-limiter';

const envVar = process.env;

// https://regex101.com/r/aNDjmI/1
const regExp = /^API_RATE_LIMIT_(\w+)_ENDPOINT(_WITH_REGEXP)?$/;

const generateApiRateLimitConfigFromEndpoint = (envVar: NodeJS.ProcessEnv, targets: string[], withRegExp: boolean): IApiRateLimitEndpointMap => {
  const apiRateLimitConfig: IApiRateLimitEndpointMap = {};
  targets.forEach((target) => {

    const endpointKey = withRegExp ? `API_RATE_LIMIT_${target}_ENDPOINT_WITH_REGEXP` : `API_RATE_LIMIT_${target}_ENDPOINT`;

    const endpoint = envVar[endpointKey];

    if (endpoint == null) {
      return;
    }
    const methodKey = `API_RATE_LIMIT_${target}_METHODS`;
    const maxRequestsKey = `API_RATE_LIMIT_${target}_MAX_REQUESTS`;
    const method = envVar[methodKey] ?? 'ALL';
    const maxRequests = Number(envVar[maxRequestsKey]);

    if (endpoint == null || maxRequests == null) {
      return;
    }

    const config = {
      method,
      maxRequests,
    };

    apiRateLimitConfig[endpoint] = config;
  });

  return apiRateLimitConfig;
};

type ApiRateLimitConfigResult = {
  'withoutRegExp': IApiRateLimitEndpointMap,
  'withRegExp': IApiRateLimitEndpointMap
}

export const generateApiRateLimitConfig = (): ApiRateLimitConfigResult => {

  const apiRateConfigTargets: string[] = [];
  const apiRateConfigTargetsWithRegExp: string[] = [];
  Object.keys(envVar).forEach((key) => {
    const result = key.match(regExp);

    if (result == null) { return null }

    const target = result[1];
    const isWithRegExp = result[2] != null;

    if (isWithRegExp) {
      apiRateConfigTargetsWithRegExp.push(target);
    }
    else {
      apiRateConfigTargets.push(target);
    }
  });

  // sort priority
  apiRateConfigTargets.sort();
  apiRateConfigTargetsWithRegExp.sort();

  // get config
  const apiRateLimitConfig = generateApiRateLimitConfigFromEndpoint(envVar, apiRateConfigTargets, false);
  const apiRateLimitConfigWithRegExp = generateApiRateLimitConfigFromEndpoint(envVar, apiRateConfigTargetsWithRegExp, true);

  const config = { ...defaultConfig, ...apiRateLimitConfig };
  const configWithRegExp = { ...defaultConfigWithRegExp, ...apiRateLimitConfigWithRegExp };

  const result: ApiRateLimitConfigResult = {
    withoutRegExp: config,
    withRegExp: configWithRegExp,
  };


  return result;
};