mirror of
https://github.com/bulwarkmail/native.git
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319 lines
9.1 KiB
TypeScript
319 lines
9.1 KiB
TypeScript
/**
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* Minimal TNEF (Transport Neutral Encapsulation Format) parser. Port of the
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* webmail's `lib/tnef.ts` without the debug logging.
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*
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* Parses winmail.dat files sent by Microsoft Outlook to extract the HTML
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* body, plain text body, and embedded attachments.
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*
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* Reference: MS-OXTNEF / MS-TNEF specification.
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*/
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const TNEF_SIGNATURE = 0x223e9f78;
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const LVL_MESSAGE = 0x01;
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const LVL_ATTACHMENT = 0x02;
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// Message-level attribute IDs
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const attBody = 0x0002800c;
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const attMAPIProps = 0x00069003;
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// Attachment-level attribute IDs
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const attAttachRenddata = 0x00069002;
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const attAttachData = 0x0006800f;
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const attAttachTitle = 0x00018010;
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const attAttachment = 0x00069005;
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// MAPI property types
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const PT_SHORT = 0x0002;
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const PT_LONG = 0x0003;
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const PT_BOOLEAN = 0x000b;
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const PT_STRING8 = 0x001e;
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const PT_UNICODE = 0x001f;
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const PT_BINARY = 0x0102;
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const PT_SYSTIME = 0x0040;
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const PT_CLSID = 0x0048;
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const PT_I8 = 0x0014;
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const MV_FLAG = 0x1000;
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// MAPI property IDs
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const PR_BODY = 0x1000;
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const PR_BODY_HTML = 0x1013;
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const PR_ATTACH_LONG_FILENAME = 0x3707;
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const PR_ATTACH_MIME_TAG = 0x370e;
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const PR_ATTACH_DATA_BIN = 0x3701;
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export interface TnefAttachment {
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name: string;
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mimeType: string;
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data: Uint8Array;
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}
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export interface TnefResult {
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body: string | null;
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htmlBody: string | null;
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attachments: TnefAttachment[];
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}
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class BinaryReader {
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private view: DataView;
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private offset: number;
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private bytes: Uint8Array;
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constructor(data: Uint8Array) {
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this.bytes = data;
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this.view = new DataView(data.buffer, data.byteOffset, data.byteLength);
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this.offset = 0;
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}
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readUint8(): number {
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const val = this.view.getUint8(this.offset);
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this.offset += 1;
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return val;
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}
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readUint16LE(): number {
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const val = this.view.getUint16(this.offset, true);
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this.offset += 2;
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return val;
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}
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readUint32LE(): number {
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const val = this.view.getUint32(this.offset, true);
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this.offset += 4;
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return val;
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}
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readBytes(length: number): Uint8Array {
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const slice = this.bytes.slice(this.offset, this.offset + length);
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this.offset += length;
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return slice;
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}
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skip(n: number): void {
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this.offset += n;
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}
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get remaining(): number {
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return this.bytes.byteLength - this.offset;
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}
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}
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function pad4(len: number): number {
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return (4 - (len % 4)) % 4;
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}
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function decodeUtf8(bytes: Uint8Array): string {
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return new TextDecoder('utf-8').decode(bytes);
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}
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function decodeUtf16le(bytes: Uint8Array): string {
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try {
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return new TextDecoder('utf-16le').decode(bytes);
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} catch {
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// Hermes' TextDecoder only guarantees utf-8; decode by hand.
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let out = '';
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for (let i = 0; i + 1 < bytes.length; i += 2) {
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out += String.fromCharCode(bytes[i] | (bytes[i + 1] << 8));
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}
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return out;
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}
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}
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function readMAPIFixedValue(r: BinaryReader, propType: number): Uint8Array | number | null {
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switch (propType) {
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case PT_SHORT: {
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const val = r.readUint16LE();
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r.skip(2);
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return val;
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}
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case PT_LONG:
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case PT_BOOLEAN:
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return r.readUint32LE();
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case PT_I8:
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case PT_SYSTIME:
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return r.readBytes(8);
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case PT_CLSID:
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return r.readBytes(16);
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default:
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if (r.remaining >= 4) return r.readBytes(4);
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return null;
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}
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}
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function readMAPIVarValue(r: BinaryReader): Uint8Array | null {
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if (r.remaining < 4) return null;
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const length = r.readUint32LE();
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if (length > r.remaining) return null;
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const data = r.readBytes(length);
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r.skip(pad4(length));
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return data;
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}
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function isVarLengthType(baseType: number): boolean {
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return baseType === PT_STRING8 || baseType === PT_UNICODE || baseType === PT_BINARY;
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}
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function decodeMAPIString(data: Uint8Array, propType: number): string {
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if (propType === PT_UNICODE) {
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let len = data.byteLength;
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if (len >= 2 && data[len - 1] === 0 && data[len - 2] === 0) len -= 2;
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return decodeUtf16le(data.subarray(0, len));
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}
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let len = data.byteLength;
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if (len >= 1 && data[len - 1] === 0) len -= 1;
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return decodeUtf8(data.subarray(0, len));
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}
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function parseMAPIProps(data: Uint8Array): Map<number, { type: number; value: Uint8Array | number | null }> {
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const props = new Map<number, { type: number; value: Uint8Array | number | null }>();
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const r = new BinaryReader(data);
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if (r.remaining < 4) return props;
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const count = r.readUint32LE();
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for (let i = 0; i < count && r.remaining >= 4; i++) {
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const propType = r.readUint16LE();
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const propID = r.readUint16LE();
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// Named properties (ID >= 0x8000) carry extra GUID + name data
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if (propID >= 0x8000) {
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if (r.remaining < 20) break;
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r.skip(16);
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const kind = r.readUint32LE();
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if (kind === 0) {
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if (r.remaining < 4) break;
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r.skip(4);
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} else {
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if (r.remaining < 4) break;
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const nameLen = r.readUint32LE();
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if (nameLen > r.remaining) break;
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r.skip(nameLen);
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r.skip(pad4(nameLen));
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}
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}
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const baseType = propType & 0x0fff;
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const isMultiValue = (propType & MV_FLAG) !== 0;
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if (isVarLengthType(baseType)) {
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if (r.remaining < 4) break;
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const valueCount = r.readUint32LE();
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let lastValue: Uint8Array | null = null;
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for (let j = 0; j < valueCount && r.remaining > 0; j++) {
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lastValue = readMAPIVarValue(r);
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}
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if (!isMultiValue && lastValue) {
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props.set(propID, { type: propType, value: lastValue });
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}
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} else if (isMultiValue) {
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if (r.remaining < 4) break;
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const valueCount = r.readUint32LE();
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for (let j = 0; j < valueCount && r.remaining > 0; j++) {
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readMAPIFixedValue(r, baseType);
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}
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} else {
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const value = readMAPIFixedValue(r, baseType);
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props.set(propID, { type: propType, value });
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}
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}
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return props;
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}
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/** Parse a TNEF (winmail.dat) file and extract the body and attachments. */
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export function parseTnef(data: Uint8Array): TnefResult {
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const result: TnefResult = { body: null, htmlBody: null, attachments: [] };
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if (data.byteLength < 6) return result;
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const r = new BinaryReader(data);
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const signature = r.readUint32LE();
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if (signature !== TNEF_SIGNATURE) return result;
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r.skip(2); // legacy key
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let curAttach: { name: string; mimeType: string; data: Uint8Array | null } | null = null;
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while (r.remaining >= 11) {
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const level = r.readUint8();
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const attrID = r.readUint32LE();
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const attrLen = r.readUint32LE();
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if (attrLen > r.remaining - 2) break;
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const attrData = r.readBytes(attrLen);
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r.skip(2); // checksum
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if (level === LVL_MESSAGE) {
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if (attrID === attBody) {
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result.body = decodeUtf8(attrData);
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} else if (attrID === attMAPIProps) {
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const props = parseMAPIProps(attrData);
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const htmlProp = props.get(PR_BODY_HTML);
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if (htmlProp?.value instanceof Uint8Array) {
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const baseType = htmlProp.type & 0x0fff;
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result.htmlBody = baseType === PT_STRING8 || baseType === PT_UNICODE
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? decodeMAPIString(htmlProp.value, baseType)
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: decodeUtf8(htmlProp.value);
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}
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if (!result.body) {
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const bodyProp = props.get(PR_BODY);
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if (bodyProp?.value instanceof Uint8Array) {
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result.body = decodeMAPIString(bodyProp.value, bodyProp.type & 0x0fff);
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}
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}
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}
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} else if (level === LVL_ATTACHMENT) {
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if (attrID === attAttachRenddata) {
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if (curAttach?.data) {
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result.attachments.push({ name: curAttach.name, mimeType: curAttach.mimeType, data: curAttach.data });
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}
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curAttach = { name: 'attachment', mimeType: 'application/octet-stream', data: null };
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} else if (attrID === attAttachTitle && curAttach) {
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let len = attrData.byteLength;
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if (len > 0 && attrData[len - 1] === 0) len--;
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curAttach.name = decodeUtf8(attrData.subarray(0, len));
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} else if (attrID === attAttachData && curAttach) {
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curAttach.data = attrData;
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} else if (attrID === attAttachment && curAttach) {
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const props = parseMAPIProps(attrData);
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const longName = props.get(PR_ATTACH_LONG_FILENAME);
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if (longName?.value instanceof Uint8Array) {
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curAttach.name = decodeMAPIString(longName.value, longName.type & 0x0fff);
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}
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const mimeTag = props.get(PR_ATTACH_MIME_TAG);
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if (mimeTag?.value instanceof Uint8Array) {
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curAttach.mimeType = decodeMAPIString(mimeTag.value, mimeTag.type & 0x0fff);
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}
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const attachData = props.get(PR_ATTACH_DATA_BIN);
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if (attachData?.value instanceof Uint8Array) {
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curAttach.data = attachData.value;
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}
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}
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}
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}
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if (curAttach?.data) {
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result.attachments.push({ name: curAttach.name, mimeType: curAttach.mimeType, data: curAttach.data });
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}
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return result;
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}
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/** Check if a MIME attachment is a TNEF (winmail.dat) file. */
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export function isTnefAttachment(name?: string | null, type?: string): boolean {
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const lowerName = (name || '').toLowerCase();
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const lowerType = (type || '').toLowerCase();
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return (
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lowerName === 'winmail.dat'
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|| lowerType === 'application/ms-tnef'
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|| lowerType === 'application/vnd.ms-tnef'
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);
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}
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