webmail/lib/__tests__/tnef.test.ts

import { describe, it, expect, vi } from 'vitest';
import { parseTnef, isTnefAttachment } from '@/lib/tnef';

vi.mock('@/lib/debug', () => ({
  debug: { group: () => {}, groupEnd: () => {}, log: () => {}, warn: () => {}, table: () => {} },
}));

// ── tiny little-endian writer mirroring the parser's BinaryReader ─────────────
class W {
  private bytes: number[] = [];
  u8(n: number) { this.bytes.push(n & 0xff); return this; }
  u16(n: number) { return this.u8(n).u8(n >>> 8); }
  u32(n: number) { return this.u8(n).u8(n >>> 8).u8(n >>> 16).u8(n >>> 24); }
  raw(arr: number[]) { for (const b of arr) this.u8(b); return this; }
  build() { return new Uint8Array(this.bytes); }
}

const TNEF_SIGNATURE = 0x223e9f78;
const LVL_MESSAGE = 0x01;
const LVL_ATTACHMENT = 0x02;
const attBody = 0x0002800c;
const attMAPIProps = 0x00069003;
const attAttachRenddata = 0x00069002;
const attAttachData = 0x0006800f;
const attAttachTitle = 0x00018010;
const PR_BODY_HTML = 0x1013;
const PT_STRING8 = 0x001e;

const enc = (s: string) => [...new TextEncoder().encode(s)];

function header(w: W) { return w.u32(TNEF_SIGNATURE).u16(0); }

function record(w: W, level: number, attrID: number, data: number[]) {
  w.u8(level).u32(attrID).u32(data.length).raw(data).u16(0); // ...data + 2-byte checksum
  return w;
}

/** One length-prefixed STRING8 MAPI property block. */
function mapiStringProp(propID: number, str: string): number[] {
  const w = new W();
  w.u32(1); // property count
  w.u16(PT_STRING8).u16(propID);
  const val = enc(str);
  w.u32(1); // value count
  w.u32(val.length).raw(val);
  for (let i = 0; i < (4 - (val.length % 4)) % 4; i++) w.u8(0); // pad to 4
  return [...w.build()];
}

describe('parseTnef', () => {
  it('returns an empty result for data smaller than 6 bytes', () => {
    expect(parseTnef(new Uint8Array([1, 2, 3]))).toEqual({ body: null, htmlBody: null, attachments: [] });
  });

  it('returns an empty result for an invalid signature', () => {
    const buf = new W().u32(0xdeadbeef).u16(0).build();
    expect(parseTnef(buf)).toEqual({ body: null, htmlBody: null, attachments: [] });
  });

  it('extracts a plain-text body from an attBody attribute', () => {
    const w = header(new W());
    record(w, LVL_MESSAGE, attBody, enc('Hello body'));
    const r = parseTnef(w.build());
    expect(r.body).toBe('Hello body');
    expect(r.htmlBody).toBeNull();
    expect(r.attachments).toEqual([]);
  });

  it('extracts an HTML body from PR_BODY_HTML in MAPI props', () => {
    const w = header(new W());
    record(w, LVL_MESSAGE, attMAPIProps, mapiStringProp(PR_BODY_HTML, '<b>hi</b>\0'));
    const r = parseTnef(w.build());
    expect(r.htmlBody).toBe('<b>hi</b>'); // trailing NUL stripped
  });

  it('assembles an attachment from renddata + title + data', () => {
    const w = header(new W());
    record(w, LVL_ATTACHMENT, attAttachRenddata, [0, 0]); // start attachment
    record(w, LVL_ATTACHMENT, attAttachTitle, enc('file.txt\0'));
    record(w, LVL_ATTACHMENT, attAttachData, [1, 2, 3, 4]);
    const r = parseTnef(w.build());
    expect(r.attachments).toHaveLength(1);
    expect(r.attachments[0].name).toBe('file.txt');
    expect(r.attachments[0].mimeType).toBe('application/octet-stream');
    expect([...r.attachments[0].data]).toEqual([1, 2, 3, 4]);
  });

  it('stops at a truncated attribute (declared length exceeds remaining)', () => {
    // sig + header, then an attribute header claiming 999 bytes with no payload.
    const w = header(new W());
    w.u8(LVL_MESSAGE).u32(attBody).u32(999);
    const r = parseTnef(w.build());
    expect(r).toEqual({ body: null, htmlBody: null, attachments: [] });
  });

  it.each([
    ['multi-valued STRING8', 0x101e],
    ['multi-valued unknown fixed type', 0x1099],
  ])('returns at once for a %s property claiming 0xFFFFFFFF values', (_label, propType) => {
    // 31 bytes: one MAPI prop whose value count asks for 2^32 values, followed
    // by two bytes that are too short to hold even one.
    const mapi = new W().u32(1).u16(propType).u16(0x0001).u32(0xffffffff).raw([0, 0]).build();
    const w = header(new W());
    record(w, LVL_MESSAGE, attMAPIProps, [...mapi]);
    record(w, LVL_MESSAGE, attMAPIProps, [...mapi]);
    record(w, LVL_MESSAGE, attMAPIProps, [...mapi]);

    const start = performance.now();
    const r = parseTnef(w.build());
    expect(performance.now() - start).toBeLessThan(100);
    expect(r).toEqual({ body: null, htmlBody: null, attachments: [] });
  });
});

describe('isTnefAttachment', () => {
  it('matches winmail.dat by name (case-insensitive)', () => {
    expect(isTnefAttachment('winmail.dat')).toBe(true);
    expect(isTnefAttachment('WinMail.DAT')).toBe(true);
  });

  it('matches the ms-tnef MIME types', () => {
    expect(isTnefAttachment('x', 'application/ms-tnef')).toBe(true);
    expect(isTnefAttachment('x', 'application/vnd.ms-tnef')).toBe(true);
  });

  it('returns false for ordinary attachments and missing values', () => {
    expect(isTnefAttachment('document.pdf', 'application/pdf')).toBe(false);
    expect(isTnefAttachment()).toBe(false);
  });
});