自ホスト以外からのTCPリクエストを拒否する

index.js

const net = require('net');

const server = net.createServer();

server.on('listening', () => {
    const {
        address,
        port,
    } = server.address();
    console.info(`Server started. (IP:port = ${address}:${port})`);
});

const okHttpResponse = `HTTP/1.0 200 OK

ok
`;

const ngHttpResponse = `HTTP/1.0 403 Forbidden

ng
`;

server.on('connection', connection => {
    const {
        remoteAddress,
        localAddress,
    } = connection;

    // 自ホストからのリクエスト
    // 1. 127.0.0.0/8 (127.0.0.1 や 127.1.2.3 など) 宛にリクエストした場合
    // 2. 自 IPアドレス宛の通信 (192.168.0.13 や  192.168.99.1 など)
    const fromSelfHost = remoteAddress === '127.0.0.1' || remoteAddress === localAddress;


    connection.once('data', data => {
        const requestLine = data.toString().split(/[\r\n]/)[0];
        console.info({
            remoteAddress,
            localAddress,
            requestLine,
            fromSelfHost,
        });
    });

    connection.end(fromSelfHost ? okHttpResponse : ngHttpResponse);
});

server.listen(3000, '0.0.0.0');