frida-interception-and-unpinning/config.js

/**************************************************************************************************
 *
 * This file defines various config parameters, used later within the other scripts.
 *
 * In all cases, you'll want to set CERT_PEM and likely PROXY_HOST and PROXY_PORT.
 *
 * Source available at https://github.com/httptoolkit/frida-interception-and-unpinning/
 * SPDX-License-Identifier: AGPL-3.0-or-later
 * SPDX-FileCopyrightText: Tim Perry <tim@httptoolkit.com>
 *
 *************************************************************************************************/

// Put your CA certificate data here in PEM format:
const CERT_PEM = `-----BEGIN CERTIFICATE-----

[!! Put your CA certificate data here, in PEM format !!]

-----END CERTIFICATE-----`;

// Put your intercepting proxy's address here:
const PROXY_HOST = '127.0.0.1';
const PROXY_PORT = 8000;

// If you like, set to to true to enable extra logging:
const DEBUG_MODE = false;

// If you find issues with non-HTTP traffic being captured (due to the
// native connect hook script) you can add ports here to exempt traffic
// on that port from being redirected. Note that this will only affect
// traffic captured by the raw connection hook - for apps using the
// system HTTP proxy settings, traffic on these ports will still be
// sent via the proxy and intercepted despite this setting.
const IGNORED_NON_HTTP_PORTS = [];


// ----------------------------------------------------------------------------
// You don't need to modify any of the below, it just checks and applies some
// of the configuration that you've entered above.
// ----------------------------------------------------------------------------


if (DEBUG_MODE) {
    // Add logging just for clean output & to separate reloads:
    console.log('\n*** Starting scripts ***');
    if (Java.available) {
        Java.perform(() => {
            setTimeout(() => console.log('*** Scripts completed ***\n'), 5);
            // (We assume that nothing else will take more than 5ms, but app startup
            // probably will, so this should separate script & runtime logs)
        });
    } else {
        setTimeout(() => console.log('*** Scripts completed ***\n'), 5);
        // (We assume that nothing else will take more than 5ms, but app startup
        // probably will, so this should separate script & runtime logs)
    }
} else {
    console.log(''); // Add just a single newline, for minimal clarity
}

// Check the certificate (without literally including the instruction phrasing
// here, as that can be confusing for some users):
if (CERT_PEM.match(/\[!!.* CA certificate data .* !!\]/)) {
    throw new Error('No certificate was provided' +
        '\n\n' +
        'You need to set CERT_PEM in the Frida config script ' +
        'to the contents of your CA certificate.'
    );
}



// ----------------------------------------------------------------------------
// Don't modify any of the below unless you know what you're doing!
// This section defines various utilities & calculates some constants which may
// be used by later scripts elsewhere in this project.
// ----------------------------------------------------------------------------



// As web atob & Node.js Buffer aren't available, we need to reimplement base64 decoding
// in pure JS. This is a quick rough implementation without much error handling etc!

// Base64 character set (plus padding character =) and lookup:
const BASE64_CHARS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
const BASE64_LOOKUP = new Uint8Array(123);
for (let i = 0; i < BASE64_CHARS.length; i++) {
    BASE64_LOOKUP[BASE64_CHARS.charCodeAt(i)] = i;
}


/**
 * Take a base64 string, and return the raw bytes
 * @param {string} input
 * @returns Uint8Array
 */
function decodeBase64(input) {
    // Calculate the length of the output buffer based on padding:
    let outputLength = Math.floor((input.length * 3) / 4);
    if (input[input.length - 1] === '=') outputLength--;
    if (input[input.length - 2] === '=') outputLength--;

    const output = new Uint8Array(outputLength);
    let outputPos = 0;

    // Process each 4-character block:
    for (let i = 0; i < input.length; i += 4) {
        const a = BASE64_LOOKUP[input.charCodeAt(i)];
        const b = BASE64_LOOKUP[input.charCodeAt(i + 1)];
        const c = BASE64_LOOKUP[input.charCodeAt(i + 2)];
        const d = BASE64_LOOKUP[input.charCodeAt(i + 3)];

        // Assemble into 3 bytes:
        const chunk = (a << 18) | (b << 12) | (c << 6) | d;

        // Add each byte to the output buffer, unless it's padding:
        output[outputPos++] = (chunk >> 16) & 0xff;
        if (input.charCodeAt(i + 2) !== 61) output[outputPos++] = (chunk >> 8) & 0xff;
        if (input.charCodeAt(i + 3) !== 61) output[outputPos++] = chunk & 0xff;
    }

    return output;
}

/**
 * Take a single-certificate PEM string, and return the raw DER bytes
 * @param {string} input
 * @returns Uint8Array
 */
function pemToDer(input) {
    const pemLines = input.split('\n');
    if (
        pemLines[0] !== '-----BEGIN CERTIFICATE-----' ||
        pemLines[pemLines.length- 1] !== '-----END CERTIFICATE-----'
    ) {
        throw new Error(
            'Your certificate should be in PEM format, starting & ending ' +
            'with a BEGIN CERTIFICATE & END CERTIFICATE header/footer'
        );
    }

    const base64Data = pemLines.slice(1, -1).map(l => l.trim()).join('');
    if ([...base64Data].some(c => !BASE64_CHARS.includes(c))) {
        throw new Error(
            'Your certificate should be in PEM format, containing only ' +
            'base64 data between a BEGIN & END CERTIFICATE header/footer'
        );
    }

    return decodeBase64(base64Data);
}

const CERT_DER = pemToDer(CERT_PEM);