The message size check is legitimate: the size must be negotiated, which
relies on the fixed message limit up front. Sending a message larger than
that indicates that the connection is out of sync and is considered a
socket error (disconnect).
Similarly, sending a size that is too small indicates that the stream is
out-of-sync or invalid.
PiperOrigin-RevId: 207996551
Change-Id: Icd8b513d5307e9d5953dbb957ee70ceea111098d