file-type-validator-ts
Version:
Validates file extension against its actual buffer-based content type in TypeScript.
240 lines (239 loc) • 7.61 kB
JavaScript
"use strict";
/**
* Validate whether the uploaded file's actual content type
* matches its file extension using magic number detection.
*/
Object.defineProperty(exports, "__esModule", { value: true });
exports.validateFileBuffer = validateFileBuffer;
const extensionAliases = {
// 🧾 Text-based formats (no unique signature)
csv: ["txt"],
tsv: ["txt"],
log: ["txt"],
json: ["txt"],
psql: ["txt"],
sql: ["txt"],
rtf: ["txt"],
xml: ["txt"],
md: ["txt"],
sh: ["txt"],
html: ["txt"],
css: ["txt"],
yml: ["txt"],
yaml: ["txt"],
patch: ["txt"],
diff: ["txt"],
tex: ["txt"],
ps: ["txt"],
php: ["txt"],
js: ["txt"],
ts: ["txt"],
// Image formats
jpg: ["jpeg"],
jpeg: ["jpg"],
jfif: ["jpg"],
tiff: ["tif"],
tif: ["tiff"],
// 📊 Microsoft Office binary formats
xls: ["doc"],
ppt: ["doc"],
wps: ["doc"],
dot: ["doc"],
dotx: ["docx"],
pps: ["doc"],
ppsx: ["pptx"],
xlt: ["doc"], // legacy Excel template (same as .xls)
xlsm: ["xlsx"], // macro-enabled workbook
xltx: ["xlsx"], // modern template
xltm: ["xlsx"], // macro-enabled template
// 📄 Apple & Open formats (may be read as zip/plain)
numbers: ["zip", "txt"],
pages: ["zip", "txt"],
key: ["zip", "txt"],
odt: ["zip"],
ods: ["zip"],
odp: ["zip"],
// 🖼️ HEIC and related image types
heif: ["heic"],
heic: ["heif"],
// 🧳 Compressed archives (some formats overlap)
apk: ["zip"],
jar: ["zip"],
docx: ["zip"],
xlsx: ["zip"],
pptx: ["zip"],
epub: ["zip"],
// Audio formats
m4a: ["mp4"], // Both use ISO BMFF (`ftyp`)
aac: ["mp4"], // Often stored in mp4 container
// Video formats
m4v: ["mp4"], // Apple video format, based on mp4
mov: ["mp4"], // QuickTime (ftypqt, similar to mp4)
"3g2": ["3gp"],
// Other formats
db: ["sqlite"],
azw: ["mobi"],
azw3: ["mobi"],
ai: ["ps", "pdf"],
};
/**
* Get extension from file name
*/
function getFileExtension(fileName) {
var _a;
return ((_a = fileName.split(".").pop()) === null || _a === void 0 ? void 0 : _a.toLowerCase()) || "";
}
/**
* Detect content type from magic number
*/
function getContentTypeFromBuffer(buffer) {
const hex = buffer.toString("hex", 0, 12).toUpperCase();
const ascii = buffer.toString("ascii", 8, 12);
// --- Image formats ---
if (hex.startsWith("FFD8FF"))
return "jpg";
if (hex.startsWith("89504E47"))
return "png";
if (hex.startsWith("47494638"))
return "gif";
if (hex.startsWith("424D"))
return "bmp";
if (hex.startsWith("49492A00") || hex.startsWith("4D4D002A"))
return "tiff";
if (hex.startsWith("00000100") || hex.startsWith("00000200"))
return "ico";
if (hex.startsWith("52494646") && ascii === "WEBP")
return "webp";
// --- Document formats ---
if (hex.startsWith("25504446"))
return "pdf";
if (hex.startsWith("D0CF11E0"))
return "doc"; // could also be xls, ppt
if (hex.startsWith("FF575043"))
return "wpd";
if (hex.startsWith("504B0304"))
return "zip-based"; // docx, xlsx, pptx, jar, apk
// --- Archive formats ---
if (hex.startsWith("52617221"))
return "rar";
if (hex.startsWith("1F8B08"))
return "gz";
if (hex.startsWith("213C617263683E0A"))
return "deb";
if (hex.startsWith("504B0304") && buffer.includes(Buffer.from("mimetypeapplication/epub+zip"))) {
return "epub";
}
// --- .tar ---
const ustar = buffer.toString("ascii", 257, 262);
if (ustar === "ustar")
return "tar";
// --- .iso ---
if (buffer.length > 32774) {
const isoMagic = buffer.toString("ascii", 32769, 32774);
if (isoMagic === "CD001")
return "iso";
}
// --- SVG (XML-based image) ---
const asciiStart = buffer.toString("utf8", 0, 100).toLowerCase();
if (asciiStart.includes("<svg") && asciiStart.includes("<"))
return "svg";
// --- Video formats ---
if (hex.startsWith("3026B2758E66CF11"))
return "wmv"; // ASF header
if (hex.startsWith("1A45DFA3"))
return "webm";
if (hex.startsWith("52494646")) {
const riffType = buffer.toString("ascii", 8, 12);
if (riffType === "AVI ")
return "avi";
if (riffType === "WAVE")
return "wav"; // RIFF but it's audio
}
const ftyp = buffer.toString("ascii", 4, 12).toLowerCase();
if (ftyp.startsWith("ftyp3gp") || ftyp.startsWith("ftyp3g2"))
return "3gp";
// --- Audio formats ---
if (hex.startsWith("494433"))
return "mp3"; // ID3
if (hex.startsWith("FFFB"))
return "mp3"; // MPEG-1 Layer III frame
if (hex.startsWith("4F676753"))
return "ogg"; // OggS
// other formats
if (hex.startsWith("377ABCAF271C"))
return "7z";
if (hex.startsWith("4D5A"))
return "exe";
if (hex.startsWith("53514C69746520666F726D61"))
return "sqlite";
if (hex.startsWith("00010000"))
return "mdb";
if (buffer.length > 68 && buffer.toString("ascii", 60, 68) === "BOOKMOBI")
return "mobi";
if (hex.startsWith("38425053"))
return "psd";
if (hex.startsWith("25215053"))
return "ai"; // EPS-based
if (hex.startsWith("25504446"))
return "ai"; // PDF-based
if (hex.startsWith("0606EDF5"))
return "indd";
// --- Audio/Video: ISO Base Media File Format (MP4, M4A, MOV, etc.) ---
const ftypTag = buffer.toString("ascii", 4, 8);
const brand = buffer.toString("ascii", 8, 12).trim();
if (ftypTag === "ftyp") {
const isoBrands = ["mp42", "isom", "iso2", "avc1"];
const m4aBrands = ["M4A", "M4B", "mp71"];
const movBrands = ["qt"];
if (isoBrands.includes(brand))
return "mp4";
if (m4aBrands.includes(brand))
return "m4a";
if (movBrands.includes(brand))
return "mov";
}
// --- HEIC/HEIF ---
if (buffer.toString("ascii", 4, 12).includes("ftyp")) {
const heicBrand = buffer.toString("ascii", 8, 12).toLowerCase();
if (["heic", "heix", "mif1", "msf1"].includes(heicBrand))
return "heic";
}
// --- Plain text fallback (UTF-8 printable characters only) ---
const sample = buffer.toString("utf8", 0, 512);
if (/^[\x20-\x7E\r\n\t]+$/.test(sample))
return "txt";
return "unknown";
}
/**
* Check ZIP-based Office document types
*/
function checkZipBasedFormat(buffer) {
const content = buffer.toString();
if (content.includes("[Content_Types].xml")) {
if (content.includes("word/document.xml"))
return "docx";
if (content.includes("xl/workbook.xml"))
return "xlsx";
if (content.includes("ppt/presentation.xml"))
return "pptx";
}
return "zip";
}
/**
* Final validation logic
*/
async function validateFileBuffer(buffer, originalName) {
var _a, _b;
const extension = getFileExtension(originalName);
let actualType = getContentTypeFromBuffer(buffer);
if (actualType === "zip-based") {
actualType = checkZipBasedFormat(buffer);
}
const isValid = actualType === extension || ((_b = (_a = extensionAliases[extension]) === null || _a === void 0 ? void 0 : _a.includes(actualType)) !== null && _b !== void 0 ? _b : false);
return {
fileName: originalName,
extension,
actualType,
isValid,
};
}