wifi_in_de_trein.js

// Copyright (c) 2024 Antoni Spaanderman
//
// wifi_in_de_trein.js
// GitHub Gist link: https://gist.github.com/antonilol/941ce3c44aaf5bee35669f69239b5727
// Version: 1.0.1

const http = require('http');

const DETECTPORTAL = 'http://detectportal.firefox.com/canonical.html';

// utility function to send an HTTP request
// to keep it simple, only method and url
// the callback gets the http request and response objects and a resolve function
// call resolve (with values) to return from the async function
function httpRequest(method, url, cb) {
    return new Promise(resolve => {
        const req = http.request(url, { method });
        req
            .on('response', res => cb(req, res, resolve))
            .on('error', err => {
                console.log('request error, no network?');
                console.log(err);
                process.exit(1);
            })
            .end();
    });
}

function getLoginUrl() {
    return httpRequest('GET', DETECTPORTAL, (req, res, resolve) => {
        if (res.statusCode == 200) {
            resolve({ needsLogin: false });
        } else if (res.statusCode == 302) {
            resolve({ needsLogin: true, loginUrl: res.headers.location });
        } else {
            console.log(`statusCode != 302, but ${req.res.statusCode}`);
            process.exit(1);
        }
    });
}

function getCsrfTokenFromLoginPage(loginUrl) {
    const CSRF_TOKEN_SEARCH_STRING = 'csrfToken" value="';

    return httpRequest('GET', loginUrl, (req, res, resolve) => {
        if (res.statusCode != 200) {
            console.log(`login page returned status code ${res.statusCode}`);
            process.exit(1);
        }
        const len = res.headers['content-length'];
        let data = '';
        let dataLen = 0;
        let foundSearchString = false;
        let foundCsrfToken = false;
        if (len != 0) {
            const numLen = Math.floor(Math.log10(len)) + 1;
            console.log(`receiving login page   0.0% (${' '.repeat(numLen - 1)}0/${len} bytes)`);
            res.on('data', chunk => {
                data += chunk;
                dataLen += chunk.length;
                console.log(
                    `receiving login page ${(dataLen * 100 / len).toFixed(1).padStart(5)}% ` +
                    `(${dataLen.toString().padStart(numLen)}/${len} bytes)`
                );
                if (!foundSearchString) {
                    while (data.length >= CSRF_TOKEN_SEARCH_STRING.length) {
                        if (data.startsWith(CSRF_TOKEN_SEARCH_STRING)) {
                            foundSearchString = true;
                            data = data.slice(CSRF_TOKEN_SEARCH_STRING.length);
                            break;
                        }
                        data = data.slice(1);
                    }
                }
                if (foundSearchString) {
                    const tokenEnd = data.indexOf('"');
                    if (tokenEnd != -1) {
                        const csrfToken = data.slice(0, tokenEnd);
                        foundCsrfToken = true;
                        if (dataLen != len) {
                            console.log('CSRF token already found, no need to finish the request');
                        }
                        if (tokenEnd != 32) {
                            console.log(`Warning: unusual CSRF token length: ${tokenEnd}, expected 32`);
                        }
                        req.abort();
                        resolve(csrfToken);
                    }
                }
            });
        }
        res.on('end', () => {
            if (!foundCsrfToken) {
                throw new Error("csrfToken not found");
            }
        });
    });
}

function login(csrfToken) {
    return httpRequest(
        'POST',
        `http://portal.nstrein.ns.nl/nstrein:main/internet?csrfToken=${csrfToken}`,
        (req, res, resolve) => {
            let data = '';
            res.on('data', chunk => {
                data += chunk;
            });
            res.on('end', () => {
                resolve();
            });
        },
    );
}

main();
async function main() {
    console.log('requesting login url from detectportal...');
    const { loginUrl, needsLogin } = await getLoginUrl();
    if (!needsLogin) {
        console.log('no login needed');
        process.exit(0);
    }

    if (!loginUrl.startsWith('http://portal.nstrein.ns.nl/')) {
        console.log('unknown network, login manually');
        process.exit(1);
    }

    console.log('getting login page...');
    // get CSRF token, here a 16 byte hex encoded string (32 hex chars)
    const csrfToken = await getCsrfTokenFromLoginPage(loginUrl);

    for (let i = 0; i < 5; i++) {
        console.log('logging in...');
        await login(csrfToken);

        console.log('checking login status...');
        if ((await getLoginUrl()).needsLogin) {
            console.log('login failed');
        } else {
            console.log('login successful');
            process.exit(0);
        }
    }

    console.log('giving up');
    process.exit(1);
}