port-sniffer task

submissions/Vitamin/port-sniffer/helpers.js

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+const help = `
+    Usage: sniffer.js [--help] [--ports <number>-<number>] [--host <value>]
+
+    These are commands used in sniffer application: 
+
+        host       Host address, IP or URL.
+                   Examples: --host ukr.net,
+                             --host 172.217.3.110
+
+        ports      Ports range. Numbers must be more than 0 and less than 65535.
+                   Examples: --port 30-562,
+                             --port 1-65535.
+
+        help       Show all commands.
+`;
+const compose = (...fns) => fns.reduce((f, g) => (...args) => f(g(...args)));
+
+const composeAsync = (...fns) => async x => {
+  let res = x;
+  for (const fn of fns) {
+    res = await fn(res);
+  }
+  return res;
+};
+
+module.exports = { help, compose, composeAsync };

submissions/Vitamin/port-sniffer/sniffer.js

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+const Net = require("net");
+const dns = require("dns").promises;
+const { help } = require("./helpers");
+
+const [, , ...arguments] = process.argv;
+const [minPortValue, maxPortValue] = [0, 65535];
+
+const ipToURL = async host => {
+  try {
+    const result = await dns.lookup(host);
+    return await result.address;
+  } catch (err) {
+    throw Error("Invalid host");
+  }
+};
+
+const isPortInRange = port => port >= minPortValue && port <= maxPortValue;
+
+const getPortsRange = ports => {
+  const [firstPort, last] = ports.split("-");
+  const lastPort = isPortInRange(last) ? last : firstPort;
+  if (isPortInRange(firstPort)) {
+    return [firstPort, lastPort];
+  } else {
+    console.log("Invalid ports range");
+    process.exit(1);
+  }
+};
+
+const tryToConnect = (host, port) => {
+  const client = new Net.Socket();
+  client.setTimeout(300);
+  client.connect({ port, host });
+  return new Promise(resolve => {
+    client.on("connect", () => {
+      process.stdout.write(".");
+      client.destroy();
+      return resolve(port);
+    });
+    client.on("timeout", () => {
+      client.destroy();
+      return resolve(false);
+    });
+    client.on("error", () => {
+      client.destroy();
+      return resolve(false);
+    });
+  });
+};
+
+const getOpenedPorts = async ({ host, firstPort, lastPort }) => {
+  const promises = [];
+  for (let i = firstPort; i <= lastPort; i++) {
+    promises.push(tryToConnect(host, i));
+  }
+  const ports = await Promise.all(promises);
+  return ports.filter(Boolean);
+};
+
+parseArguments = async args => {
+  if (args.includes("--help")) {
+    console.log(help);
+    process.exit(0);
+  } else if (
+    args.length < 4 ||
+    !args.includes("--ports") ||
+    !args.includes("--host")
+  ) {
+    console.log("Use --help to correct input");
+    process.exit(1);
+  }
+  const [firstPort, lastPort] = getPortsRange(args[1]);
+  const host = await ipToURL(args[3]);
+  return { host, firstPort, lastPort };
+};
+
+const getMessageToLog = openPorts => {
+  if (openPorts.length > 1) return `\n${openPorts} ports are opened`;
+  else if (openPorts.length === 1) return `\n${openPorts} port is opened`;
+  return "\nAll ports in range are closed";
+};
+
+const sniffing = async args => {
+  const { host, firstPort, lastPort } = await parseArguments(args);
+  return await getOpenedPorts({ host, firstPort, lastPort });
+};
+
+sniffing(arguments)
+    .then(getMessageToLog)
+    .then(console.log);
+