Comment 42 for bug 1573594

"You can't look at the length of the returned string as the buffer is already corrupted at that point and memcached_response does not return the length either."

For you to understand why what your saying is off, you will need to spend sometime understanding how memcached_response(), which internal API call, is used in the code.

FWIW I spoke to Dormando, who has the maintainer Memcached for anyone's recent memory. The binary protocol is/being deprecated, which in turns means that SASL support will be dropped ( it was only ever supported for the binary protocol ).