The protocol length field is validated to 50 MiB, but a peer that sends
bytes which never assemble into a complete packet — for example an HTTP-mask
envelope without its terminating CRLF CRLF, which Parse() waits on
indefinitely — could grow the per-connection input buffer without bound.
handleConnection now closes the connection once unparsed buffered bytes
exceed MaxBufferedBytes (default 50 MiB + 64 KiB slack, covering the largest
legitimate packet plus its mask envelope and a read chunk).
Co-Authored-By: deepseek-v4-pro
