index.js

const cors = require('cors');
const helmet = require('helmet');
const express = require('express');
const bodyParser = require('body-parser');
const maxmind = require('./lib/maxmind-utility');
const countryList = require('./lib/countries');

const app = express();
const ipValidation = /^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$/;

app.use(cors());
app.use(helmet());
app.use(bodyParser.json());
app.disable('x-powered-by');
app.use('/assets', express.static('resources/flags'));

const getIp = async ip => {
  if (!ipValidation.test(ip)) {
    return;
  }

  const reader = await maxmind;
  return reader.get(ip);
}

app.options('/*', (req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET,PUT,POST,DELETE,OPTIONS');
  res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization, Content-Length, X-Requested-With');
  res.send(200);
});

app.post('/ip', async (req, res) => {
  const ipList = req.body.ip;

  try {
    if (!Array.isArray(ipList)) {
      res.sendStatus(400);
    }
  
    const resolvedIPList = await Promise.all(ipList.map(ip => getIp(ip) || ''));
    const flagList = resolvedIPList.map(ip => {
      const code = ip?.country?.iso_code?.toLowerCase();
      if (!code) {
        return { imagePath: 'assets/unknown.png', locationName: '未知' };
      }
      const imagePath = `assets/${code}.png`;
      const locationName = countryList[code];
      return { imagePath, locationName };
    });
    res.json(flagList);
  } catch (ex) {
    console.error(ex);
    res.sendStatus(500);
  }
});

app.listen(9977, async () => console.log('App listening on port 9977!'));