port-pid/index.js

Get the pid(s) of a process on a given port

/* eslint prefer-destructuring: 0 */
const condense = require('selective-whitespace');
const netstats = require('netstats');

const platform = process.platform;

function pushTo(target, item) {
  if (item !== '' && typeof item === 'number' && item !== 0 && target.indexOf(item) === -1) {
    target.push(item);
  }
}

// Example output to parse (macOS):
// $ lsof -i :8017
/*
 COMMAND   PID    USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
 nc      20661 michael    3u  IPv4 0x3b190d9d07c2c3db      0t0  TCP *:8017 (LISTEN)
 nc      21145 michael    3u  IPv4 0x3b190d9d054773db      0t0  TCP *:8017 (LISTEN)
 Python  21221 michael    3u  IPv4 0x3b190d9ceb8dfd7b      0t0  UDP localhost:8017
 */

// [WIN] $ netstat.exe -a -n -o | findstr :9000

/*
 TCP    0.0.0.0:9000           0.0.0.0:0              LISTENING       5220
 TCP    127.0.0.1:9000         127.0.0.1:62376        ESTABLISHED     5220
 TCP    127.0.0.1:9000         127.0.0.1:62379        ESTABLISHED     5220
 TCP    127.0.0.1:62288        127.0.0.1:9000         TIME_WAIT       0
 TCP    127.0.0.1:62299        127.0.0.1:9000         TIME_WAIT       0
 TCP    127.0.0.1:62376        127.0.0.1:9000         ESTABLISHED     7604
 TCP    127.0.0.1:62378        127.0.0.1:9000         ESTABLISHED     7604
 UDP    127.0.0.1:9000         *:*                                    1240
 */

async function processNetStats(arr) {
  const pidindex = 1;
  let items = arr.slice(1);

  if (platform === 'win32') {
    items = arr;
  }

  const pids = {
    all: [],
    tcp: [],
    udp: [],
  };

  await Promise.all(items.map((item) => {
    const values = condense(item).split(' ');
    let pid = parseInt(values[pidindex], 10);

    if (platform === 'win32') {
      pid = values.pop();
    }

    if (values.length > 1) {
      if (values.indexOf('TCP') !== -1) {
        pushTo(pids.tcp, pid);
        pushTo(pids.all, pid);
      } else if (values.indexOf('UDP') !== -1) {
        pushTo(pids.udp, pid);
        pushTo(pids.all, pid);
      }
    }

    return Promise.resolve();
  }));

  return pids;
}

function main(port) {
  if (typeof port !== 'number') {
    throw new TypeError('Expected a port number');
  }

  return new Promise(((resolve) => {
    netstats(port).then((stats) => {
      processNetStats(stats).then((ps) => {
        resolve(ps);
      });
    }).catch(() => {
      resolve({
        all: [],
        tcp: [],
        udp: [],
      });
    });
  }));
}

module.exports = main;