SSL autoconfig for SST doesn't work when certificates with utf-8 chars are used.

[venkatesh-prasad-v]

As per the recent SSL improvements in 5.7.34, the joiner generates and sends a
secret message consisting of a random string + Common Name of the SSL
certificate together within the address in State Transfer Request in order
to authenticate the donor on connection.

However, the logic of fetching the Common Name from the certificate
doesn't work well for the SSL certificates with utf-8 common name, resulting
in the SST failure.

WSREP_SST: [INFO] Encrypting with CERT: /home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/server-cert.pem, KEY: /home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/server-key.pem, CA: /home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/ca.pem (20211105 10:51:58.893)
...
WSREP_SST: [INFO] Streaming GTID file before SST (20211105 10:51:58.910)
WSREP_SST: [INFO] Evaluating xbstream -c ${INFO_FILE} | socat -u stdio openssl-connect:127.0.0.1:5020,cert=/home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/server-cert.pem,key=/home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/server-key.pem,cafile=/home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/ca.pem,verify=1,commonname='\D0\9E\D0\BF\D0\B8\D1\81\D0\B0\D0\BD\D0\B8\D0\B5 \D1\81\D0\B0\D0\B9\D1\82\D0\B0'; RC=( ${PIPESTATUS[@]} ) (20211105 10:51:58.912)
2021/11/05 10:51:58 socat[27977] E certificate is valid but its commonName does not match hostname

This is because of the fact that the logic used in https://github.com/codership/mysql-wsrep/blob/wsrep_5.7.34-25.26/scripts/wsrep_sst_xtrabackup-v2.sh#L1099-L1101 doesn't consider utf-8 chars.

In our experiment, we generated SSL certificates with the below common name and SST failed when I used them.

openssl x509 -noout -subject -in /home/venki/work/pxc/refresh/codership-mysql-wsrep/bld/pxc-node/cert/server-cert.pem -nameopt utf8         
subject=C=RU, ST=Описание сайта, L=Описание сайта, O=Описание сайта, OU=Описание сайта, CN=Описание сайта, [email protected]