@pushforge/builder/dist/lib/vapid.js

A robust, cross-platform Web Push notification library that handles VAPID authentication and payload encryption following the Web Push Protocol standard. Works in Node.js 16+, Browsers, Deno, Bun and Cloudflare Workers.

import { base64UrlEncode } from './base64.js';
import { crypto } from './crypto.js';
import { createJwt } from './jwt.js';
import { getPublicKeyFromJwk } from './utils.js';
/**
 * Constructs the VAPID headers for a push notification request.
 *
 * This function generates the necessary headers for sending a push notification
 * using the VAPID protocol, including authentication and encryption information.
 *
 * @param {PushOptions} options - The options for the push notification, including the JSON Web Key (JWK) and JWT data.
 * @param {number} payloadLength - The length of the payload being sent in the push notification.
 * @param {Uint8Array} salt - A salt value used in the encryption process.
 * @param {CryptoKey} localPublicKey - The local public key used for encryption.
 * @returns {Promise<Record<string, string> | Headers>} A promise that resolves to an object containing the VAPID headers.
 *
 * @throws {Error} Throws an error if the JWT creation fails or if key export fails.
 */
export const vapidHeaders = async (options, payloadLength, salt, localPublicKey) => {
    // Export the local public key to a raw format and encode it in Base64 URL format
    const localPublicKeyBase64 = await crypto.subtle
        .exportKey('raw', localPublicKey)
        .then((bytes) => base64UrlEncode(bytes));
    // Get the server public key from the JWK
    const serverPublicKey = getPublicKeyFromJwk(options.jwk);
    // Create the JWT for authentication
    const jwt = await createJwt(options.jwk, options.jwt);
    // Construct the header values for the VAPID request
    const headerValues = {
        Encryption: `salt=${base64UrlEncode(salt)}`,
        'Crypto-Key': `dh=${localPublicKeyBase64}`,
        'Content-Length': payloadLength.toString(),
        'Content-Type': 'application/octet-stream',
        'Content-Encoding': 'aesgcm',
        Authorization: `vapid t=${jwt}, k=${serverPublicKey}`,
    };
    let headers;
    // Add optional headers if they are defined
    if (options.ttl !== undefined)
        headerValues.TTL = options.ttl.toString();
    if (options.topic !== undefined)
        headerValues.Topic = options.topic;
    if (options.urgency !== undefined)
        headerValues.Urgency = options.urgency;
    // Create Headers object if available (for browser or Node.js 18+)
    if (typeof Headers !== 'undefined') {
        headers = new Headers(headerValues);
    }
    else {
        // Fallback for Node.js < 18 without polyfill
        headers = headerValues;
    }
    return headers; // Return the constructed headers
};