def mask

bend-kit-websocket@0.4.0.0 · websocket.bend:296

import Base
import bend-kit-bytes@0.3.3.0/bytes.bend as Bytes

296# The payload XOR the mask key (§5.3), a word at a time. key's byte k (low first) is mask octet k.
297# Masking twice gives the payload back.
298def mask(+key: U32, b: Bytes.Bytes) -> Bytes.Bytes:
299  Bytes.Bytes{+len, buf} = b
300  Bytes.Bytes{len, mask.trim(len, mask.go(U32.to_nat(Bytes.words(len)), Array.get(U32, buf, 0), 0, key))}