SnowLuma/packages/websocket/tests/extensions.test.ts

import { describe, expect, it } from 'vitest';

import { compressRaw, decompressRaw } from '../src/extensions';

describe('permessage-deflate decompression limits', () => {
    it('accepts output exactly at maxPayload', () => {
        const source = Buffer.alloc(4096, 0x61);
        const compressed = compressRaw(source);

        expect(decompressRaw(compressed, source.byteLength)).toEqual(source);
    });

    it('stops a compression bomb during inflate and maps it to WebSocket 1009', () => {
        const maxPayload = 4096;
        const compressed = compressRaw(Buffer.alloc(1024 * 1024, 0x61));
        expect(compressed.byteLength).toBeLessThan(maxPayload);

        let thrown: unknown;

        try {
            decompressRaw(compressed, maxPayload);
        } catch (error) {
            thrown = error;
        }

        expect(thrown).toMatchObject({
            code: 1009,
            message: `Message too large after inflate (maxPayload=${maxPayload})`,
            cause: { code: 'ERR_BUFFER_TOO_LARGE' },
        });
    });
});