ssl-validate-cert incorrect hostname check

ssl_verify_server_cert() function parses the output of X509_NAME_oneline() to get the value of the /CN=... field. But if this string — "/CN=" — is present as a part of the value of some other field that might cause the output to be parsed incorrectly. See https://wiki.openssl.org/index.php/Hostname_validation for examples of correct hostname validation.