grpc-node/examples/interceptors/server.js

/*
 *
 * Copyright 2024 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.
 *
 */

const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');
const parseArgs = require('minimist');

const PROTO_PATH = __dirname + '/../protos/echo.proto';

const packageDefinition = protoLoader.loadSync(
  PROTO_PATH,
  {keepCase: true,
   longs: String,
   enums: String,
   defaults: true,
   oneofs: true
  });
const echoProto = grpc.loadPackageDefinition(packageDefinition).grpc.examples.echo;

function unaryEcho(call, callback) {
  console.log(`unary echoing message ${call.request.message}`);
  callback(null, call.request);
}

function bidirectionalStreamingEcho(call) {
  call.on('data', request => {
    console.log(`bidi echoing message ${request.message}`);
    call.write(request);
  });
  call.on('end', () => {
    call.end();
  });
}

const serviceImplementation = {
  unaryEcho,
  bidirectionalStreamingEcho
}

function validateAuthorizationMetadata(metadata) {
  const authorization = metadata.get('authorization');
  if (authorization.length < 1) {
    return false;
  }
  return authorization[0] === 'some-secret-token';
}

function authInterceptor(methodDescriptor, call) {
const listener = (new grpc.ServerListenerBuilder())
  .withOnReceiveMetadata((metadata, next) => {
    if (validateAuthorizationMetadata(metadata)) {
      next(metadata);
    } else {
      call.sendStatus({
        code: grpc.status.UNAUTHENTICATED,
        details: 'Auth metadata not correct'
      });
    }
  }).build();
  const responder = (new grpc.ResponderBuilder())
    .withStart(next => {
        next(listener);
    }).build();
  return new grpc.ServerInterceptingCall(call, responder);
}

// logger is to mock a sophisticated logging system. To simplify the example, we just print out the content.
function logger(format, ...args) {
  console.log(`LOG (server):\t${format}\n`, ...args);
}

function loggingInterceptor(methodDescriptor, call) {
  const listener = new grpc.ServerListenerBuilder()
    .withOnReceiveMessage((message, next) => {
      logger(`Receive a message ${JSON.stringify(message)} at ${(new Date()).toISOString()}`);
      next(message);
    }).build();
  const responder = new grpc.ResponderBuilder()
    .withStart(next => {
      next(listener);
    })
    .withSendMessage((message, next) => {
      logger(`Send a message ${JSON.stringify(message)} at ${(new Date()).toISOString()}`);
      next(message);
    }).build();
  return new grpc.ServerInterceptingCall(call, responder);
}

function main() {
  const argv = parseArgs(process.argv.slice(2), {
    string: 'port',
    default: {port: '50051'}
  });
  const server = new grpc.Server({interceptors: [authInterceptor, loggingInterceptor]});
  server.addService(echoProto.Echo.service, serviceImplementation);
  server.bindAsync(`0.0.0.0:${argv.port}`, grpc.ServerCredentials.createInsecure(), (err, port) => {
    if (err != null) {
      return console.error(err);
    }
    console.log(`gRPC listening on ${port}`)
  });
  client = new echoProto.Echo(`localhost:${argv.port}`, grpc.credentials.createInsecure());
}

main();