leap-node/lotion/abci/src/server.js

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const net = require('net');
const debug = require('debug')('abci');
const Connection = require('./connection.js');

function createServer(app) {
  const server = net.createServer(client => {
    client.name = `${client.remoteAddress}:${client.remotePort}`;

    const conn = new Connection(client, async (req, cb) => {
      const [type] = Object.keys(req);
      let message = req[type];

      // special messages
      if (type === 'flush') {
        conn.write({ flush: {} });
        return cb();
      } else if (type === 'echo') {
        conn.write({ echo: { message: message.message } });
        return cb();
      }

      const succeed = response => {
        // respond to client
        conn.write({ [type]: response });
        cb();
      };

      const fail = err => {
        // if app throws an error, send an 'exception' response
        // and close the connection
        debug(`ABCI error on "${type}":`, err);
        message = { exception: { error: err.toString() } };
        conn.write(message);
        conn.close();
      };

      // message handler not implemented in app, send emtpy response
      if (app[type] == null) {
        return succeed({});
      }

      // call method
      try {
        let res = app[type](message);

        // method can optionally be async
        if (res instanceof Promise) {
          res = await res;
        }

        return succeed(res);
      } catch (err) {
        return fail(err);
      }
    });
  });

  return server;
}

module.exports = createServer;