Function getImageTypeFromBuffer

server/modules/logoUploadSecurity.js:54–93

(buffer)

};

const getImageTypeFromBuffer = (buffer) => {
  if (!Buffer.isBuffer(buffer) || buffer.length < 12) {
    return null;
  }

  // PNG signature: 89 50 4E 47 0D 0A 1A 0A
  if (buffer.length >= 8
    && buffer[0] === 0x89
    && buffer[1] === 0x50
    && buffer[2] === 0x4E
    && buffer[3] === 0x47
    && buffer[4] === 0x0D
    && buffer[5] === 0x0A
    && buffer[6] === 0x1A
    && buffer[7] === 0x0A
  ) {
    return "image/png";
  }

  // JPEG signature: FF D8 FF
  if (buffer[0] === 0xFF && buffer[1] === 0xD8 && buffer[2] === 0xFF) {
    return "image/jpeg";
  }

  // GIF signature: GIF87a / GIF89a
  if (buffer.toString("ascii", 0, 6) === "GIF87a"
    || buffer.toString("ascii", 0, 6) === "GIF89a"
  ) {
    return "image/gif";
  }

  // WEBP signature: RIFF....WEBP
  if (buffer.toString("ascii", 0, 4) === "RIFF"
    && buffer.toString("ascii", 8, 12) === "WEBP"
  ) {
    return "image/webp";
  }

  return null;
};

const isAllowedLogoMimeType = (mimeType) => {
  const normalizedMimeType = normalizeMimeType(mimeType);