Port sniffer

submissions/assmass13/port-sniffer/sniffer.js

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+const dns = require('dns');
+const { Socket } = require('net');
+
+const defaultPortLimits = {
+  startPort: 0,
+  endPort: 65535
+};
+const timeout = 300;
+
+const helpMessage = `Sniffer params usage:
+--host - required argument which can be either domain name, like google.com or IP address like 172.217.3.110
+--ports - limits range of ports to scan, should be provided in format (start_port)-(end_port), for instance: 3-600
+--help - flag to see hint about how to use TCP sniffer\n`;
+const hostErrorMessage = `--host parameter with its value should be passed\n`;
+const portsErrorMessage = `--ports value should be passed as a port range with limits(0-65535), like 15-333\n`;
+function lookupErrorMessage(error) {
+  return `Error ${error.code} occurred during ${error.syscall} call for '${error.hostname}' host\n`;
+}
+
+function stdoutWrite(str) {
+  process.stdout.write(str);
+}
+
+function exit(code) {
+  process.exit(code);
+}
+
+function parseArgs(args) {
+  if (args.includes('--help')) {
+    stdoutWrite(helpMessage);
+    exit(0);
+  } else if (
+    args.indexOf('--host') === -1 ||
+    !args[args.indexOf('--host') + 1]
+  ) {
+    stdoutWrite(hostErrorMessage);
+    exit(1);
+  }
+
+  return args.reduce((result, item, index, arr) => {
+    if (item.indexOf('--') === 0 && arr[index + 1]) {
+      return { ...result, [item]: arr[index + 1] };
+    }
+    return result;
+  }, {});
+}
+
+async function getAddress(host) {
+  return new Promise((resolve, reject) => {
+    dns.lookup(host, (err, address) => {
+      if (err) reject(err);
+      resolve(address);
+    });
+  }).catch(e => {
+    stdoutWrite(lookupErrorMessage(e));
+    exit(1);
+  });
+}
+
+function getPortLimits(portsRange) {
+  const arePortsValid = ports =>
+    ports.length === 2 &&
+    ports[0] >= defaultPortLimits.startPort &&
+    ports[1] > ports[0] &&
+    ports[1] <= defaultPortLimits.endPort;
+
+  const portArr = portsRange.split('-').map(portNum => parseInt(portNum, 10));
+
+  if (!arePortsValid(portArr)) {
+    stdoutWrite(portsErrorMessage);
+    exit(1);
+  }
+  return { startPort: portArr[0], endPort: portArr[1] };
+}
+
+async function scanAddressPort(address, port) {
+  return new Promise(resolve => {
+    const socket = new Socket();
+    socket.setTimeout(timeout);
+
+    socket.on('connect', () => {
+      stdoutWrite('.');
+      resolve(port);
+      socket.destroy();
+    });
+
+    socket.on('timeout', () => {
+      resolve(false);
+      socket.destroy();
+    });
+
+    socket.on('error', () => {
+      resolve(false);
+      socket.destroy();
+    });
+
+    socket.connect(port, address);
+  });
+}
+
+function getAddressOpenPorts(address, startPort, endPort) {
+  const openPorts = [];
+  for (let port = startPort; port < endPort; port += 1) {
+    openPorts.push(scanAddressPort(address, port));
+  }
+  return Promise.all(openPorts).then(values => values.filter(Number.isFinite));
+}
+
+(async function sniff() {
+  const processArgs = process.argv.slice(2);
+  const parsedArgs = parseArgs(processArgs);
+  const address = await getAddress(parsedArgs['--host']);
+  const portLimits =
+    '--ports' in parsedArgs
+      ? getPortLimits(parsedArgs['--ports'])
+      : defaultPortLimits;
+  const openPorts = await getAddressOpenPorts(
+    address,
+    portLimits.startPort,
+    portLimits.endPort
+  );
+  if (openPorts.length > 0) {
+    stdoutWrite(`\n${openPorts.join(', ')} ports are opened\n`);
+  } else {
+    stdoutWrite('No opened ports\n');
+  }
+})();