The smb library bounds checks for a message size that is too large, but
does not check for a message size that is way too small. Error out if
the message size is not at least as large as the ProtocolID 4-byte
preamble.
This fixes slice out of bound panics when checking the buffer for the
protID string for certain hosts.
Signed-off-by: Jeff Cody <jcody@censys.io>
