Zero-Allocation TypedArray Subarray View Slicing for Binary Frame Decoding in Next.js Middleware

export function parseBinaryHeader(uint8Buffer) {
  const magicHeader = uint8Buffer.subarray(0, 4);
  const payloadView = uint8Buffer.subarray(4);
  
  const isPNG = magicHeader.every((byte, i) => byte === [0x89, 0x50, 0x4e, 0x47][i]);
  return { isPNG, payload: payloadView };
}
 
export function middleware(request) {
  const headerHeader = request.headers.get('x-binary-payload');
  if (!headerHeader) return;
  const rawBytes = Uint8Array.from(Buffer.from(headerHeader, 'base64'));
  const { isPNG, payload } = parseBinaryHeader(rawBytes);
  if (!isPNG) return new Response('Invalid Format', { status: 400 });
  return NextResponse.next();
}