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Edit File: service-config.ts

/*
 * Copyright 2019 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

/* This file implements gRFC A2 and the service config spec:
 * https://github.com/grpc/proposal/blob/master/A2-service-configs-in-dns.md
 * https://github.com/grpc/grpc/blob/master/doc/service_config.md. Each
 * function here takes an object with unknown structure and returns its
 * specific object type if the input has the right structure, and throws an
 * error otherwise. */

/* The any type is purposely used here. All functions validate their input at
 * runtime */
/* eslint-disable @typescript-eslint/no-explicit-any */

import * as os from 'os';
import { Duration } from './duration';
import {
  LoadBalancingConfig,
  validateLoadBalancingConfig,
} from './load-balancer';

export interface MethodConfigName {
  service: string;
  method?: string;
}

export interface MethodConfig {
  name: MethodConfigName[];
  waitForReady?: boolean;
  timeout?: Duration;
  maxRequestBytes?: number;
  maxResponseBytes?: number;
}

export interface ServiceConfig {
  loadBalancingPolicy?: string;
  loadBalancingConfig: LoadBalancingConfig[];
  methodConfig: MethodConfig[];
}

export interface ServiceConfigCanaryConfig {
  clientLanguage?: string[];
  percentage?: number;
  clientHostname?: string[];
  serviceConfig: ServiceConfig;
}

/**
 * Recognizes a number with up to 9 digits after the decimal point, followed by
 * an "s", representing a number of seconds.
 */
const TIMEOUT_REGEX = /^\d+(\.\d{1,9})?s$/;

/**
 * Client language name used for determining whether this client matches a
 * `ServiceConfigCanaryConfig`'s `clientLanguage` list.
 */
const CLIENT_LANGUAGE_STRING = 'node';

export function validateServiceConfig(obj: any): ServiceConfig {
  const result: ServiceConfig = {
    loadBalancingConfig: [],
    methodConfig: [],
  };
  if ('loadBalancingPolicy' in obj) {
    if (typeof obj.loadBalancingPolicy === 'string') {
      result.loadBalancingPolicy = obj.loadBalancingPolicy;
    } else {
      throw new Error('Invalid service config: invalid loadBalancingPolicy');
    }
  }
  if ('loadBalancingConfig' in obj) {
    if (Array.isArray(obj.loadBalancingConfig)) {
      for (const config of obj.loadBalancingConfig) {
        result.loadBalancingConfig.push(validateLoadBalancingConfig(config));
      }
    } else {
      throw new Error('Invalid service config: invalid loadBalancingConfig');
    }
  }
  if ('methodConfig' in obj) {
    if (Array.isArray(obj.methodConfig)) {
      for (const methodConfig of obj.methodConfig) {
        result.methodConfig.push(validateMethodConfig(methodConfig));
      }
    }
  }
  // Validate method name uniqueness
  const seenMethodNames: MethodConfigName[] = [];
  for (const methodConfig of result.methodConfig) {
    for (const name of methodConfig.name) {
      for (const seenName of seenMethodNames) {
        if (
          name.service === seenName.service &&
          name.method === seenName.method
        ) {
          throw new Error(
            `Invalid service config: duplicate name ${name.service}/${name.method}`
          );
        }
      }
      seenMethodNames.push(name);
    }
  }
  return result;
}

/**
 * Find the "grpc_config" record among the TXT records, parse its value as JSON, validate its contents,
 * and select a service config with selection fields that all match this client. Most of these steps
 * can fail with an error; the caller must handle any errors thrown this way.
 * @param txtRecord The TXT record array that is output from a successful call to dns.resolveTxt
 * @param percentage A number chosen from the range [0, 100) that is used to select which config to use
 * @return The service configuration to use, given the percentage value, or null if the service config
 *     data has a valid format but none of the options match the current client.
 */
export function extractAndSelectServiceConfig(
  txtRecord: string[][],
  percentage: number
): ServiceConfig | null {
  for (const record of txtRecord) {
    if (record.length > 0 && record[0].startsWith('grpc_config=')) {
      /* Treat the list of strings in this record as a single string and remove
       * "grpc_config=" from the beginning. The rest should be a JSON string */
      const recordString = record.join('').substring('grpc_config='.length);
      const recordJson: any = JSON.parse(recordString);
      return validateAndSelectCanaryConfig(recordJson, percentage);
    }
  }
  return null;
}

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