splitHeaderUtil.js

// import Headers in NodeJS environments
// this line can safely be removed in browser environments
import { Headers } from './AbstractMessage.js';

/**
 *
 * @typedef {object} ErrorResult
 * @property {{message:string,code:string,id:string}} error
 */

/** @constant
    @type {number}
    @default
*/
const MAX_HEADER_VALUE = 3072;

/**
 *
 * @param {Headers} headers
 * @returns {Headers} split headers
 */
export function split_headers(headers) {
	headers = new Headers(headers);

	if (headers.has('x-bare-headers')) {
		const value = headers.get('x-bare-headers');

		if (value.length > MAX_HEADER_VALUE) {
			headers.delete('x-bare-headers');

			let split = 0;

			for (let i = 0; i < value.length; i += MAX_HEADER_VALUE) {
				const part = value.slice(i, i + MAX_HEADER_VALUE);

				const id = split++;
				headers.set(`x-bare-headers-${id}`, `;${part}`);
			}
		}
	}

	return headers;
}

/**
 * @description Joins headers in object, according to spec
 * @param {Headers} headers  joined headers
 */
export function join_headers(headers) {
	headers = new Headers(headers);

	const prefix = 'x-bare-headers';

	if (headers.has(`${prefix}-0`)) {
		const join = [];

		for (let [header, value] of headers) {
			if (!header.startsWith(prefix)) {
				continue;
			}

			if (!value.startsWith(';')) {
				return {
					error: {
						code: 'INVALID_BARE_HEADER',
						id: `request.headers.${header}`,
						message: `Value didn't begin with semi-colon.`,
					},
				};
			}

			value = value.slice(1);

			const id = parseInt(header.slice(prefix.length + 1));

			join[id] = value;

			headers.delete(header);
		}

		headers.set(prefix, join.join(''));
	}

	return headers;
}