@andrewwlane/ssh-keygen2/index.js

Automate ssh-keygen command for generating RSA keypairs

import childProcess from "child_process";
import path from "path";
import os from "os";
import crypto from "crypto";
import fs from "fs";

const tmpDir = os.tmpdir();

export default (opts, cb) => {
  if (typeof opts === "function") {
    cb = opts;
    opts = {};
  }
  opts = opts || {};
  let stderr = "";
  let stdout = "";
  let overwriteRefused = false;
  const location = opts.location || path.join(tmpDir, crypto.randomBytes(16).toString("hex"));
  const args = [];
  const ret = {};

  if (opts.keep) {
    ret.path = location;
  }
  if (opts.type) {
    args.push("-t", opts.type);
  }
  if (opts.bits) {
    args.push("-b", opts.bits);
  }
  args.push("-C", opts.comment || "");
  args.push("-N", opts.passphrase || opts.password || "");
  args.push("-f", location);
  args.push("-m", "PEM");

  const proc = childProcess.spawn("ssh-keygen", args);
  proc.stderr.on("data", (data) => {
    stderr += data;
  });
  proc.stdout.on("data", (data) => {
    stdout += data;

    // check for the case where we are trying to overwrite a file
    if (stdout.indexOf("already exists") >= 0 && stdout.indexOf("Overwrite") >= 0) {
      proc.stdin.write("n\n"); // send a "No" which should refuse to overwrite an existing key
      overwriteRefused = true;
    }
  });
  proc.on("exit", () => {
    if (overwriteRefused) {
      return cb(new Error("Key not generated because it would overwrite an existing file"));
    }
    return fs.readFile(location, { encoding: "ascii" }, (privateErr, privateKey) => {
      if (privateErr && privateErr.code !== "ENOENT") {
        return cb(privateErr);
      }
      if (!privateKey) {
        return cb(new Error(stderr));
      }
      ret.private = privateKey;
      return fs.readFile(`${location}.pub`, { encoding: "ascii" }, (publicErr, publicKey) => {
        if (publicErr && publicErr.code !== "ENOENT") {
          return cb(publicErr);
        }
        if (!publicKey) {
          return cb(new Error(stderr));
        }
        ret.public = publicKey;
        let match = stdout.match(/fingerprint is:\r?\n([^\r\n]+)\r?\n/);
        if (match) ret.fingerprint = match[1].trim();
        match = stdout.match(/randomart image is:\r?\n([\s\S]+)/);
        if (match) {
          ret.randomart = match[1].trim();
        }
        if (opts.keep) {
          return cb(null, ret);
        }
        return fs.unlink(location, (unlinkPrivateErr) => {
          if (unlinkPrivateErr) {
            return cb(unlinkPrivateErr);
          }
          return fs.unlink(`${location}.pub`, (unlinkPublicErr) => {
            if (unlinkPublicErr) {
              return cb(unlinkPublicErr);
            }
            return cb(null, ret);
          });
        });
      });
    });
  });
};