Function assertOoxmlArchiveWithinLimits

apps/sim/lib/file-parsers/zip-guard.ts:230–270

(
  buffer: Buffer,
  limits: OoxmlSizeLimits = DEFAULT_OOXML_SIZE_LIMITS
)

 * downstream parser's own validation and fallbacks.
 */
export function assertOoxmlArchiveWithinLimits(
  buffer: Buffer,
  limits: OoxmlSizeLimits = DEFAULT_OOXML_SIZE_LIMITS
): void {
  const totalUncompressed = sumDeclaredUncompressedSize(buffer, limits.maxTotalUncompressedBytes)
  if (totalUncompressed === null) {
    if (isZipShaped(buffer)) {
      logger.warn('Rejected ZIP-shaped archive: central directory could not be parsed', {
        compressedBytes: buffer.length,
      })
      throw new ZipBombError(
        'Unable to inspect ZIP central directory; refusing to parse an unverifiable ZIP-shaped archive'
      )
    }
    return
  }

  if (totalUncompressed > limits.maxTotalUncompressedBytes) {
    logger.warn('Rejected OOXML archive: declared expanded size exceeds limit', {
      totalUncompressed,
      maxTotalUncompressedBytes: limits.maxTotalUncompressedBytes,
      compressedBytes: buffer.length,
    })
    throw new ZipBombError(
      `Decompressed size (${totalUncompressed} bytes) exceeds the maximum allowed ${limits.maxTotalUncompressedBytes} bytes`
    )
  }

  const ratio = totalUncompressed / Math.max(buffer.length, 1)
  if (totalUncompressed > limits.ratioCheckFloorBytes && ratio > limits.maxCompressionRatio) {
    logger.warn('Rejected OOXML archive: compression ratio exceeds limit', {
      totalUncompressed,
      compressedBytes: buffer.length,
      ratio,
      maxCompressionRatio: limits.maxCompressionRatio,
    })
    throw new ZipBombError(
      `Compression ratio (${ratio.toFixed(1)}x) exceeds the maximum allowed ${limits.maxCompressionRatio}x`
    )
  }
}