TLS hostname check failure and subjectAltname extension

[Michael Ströder <michael@stroeder.com>]

HI!

We're using self-compiled OpenLDAP 2.4.27 under RHEL 6.1 linked against 
OpenSSL 1.0.0 libs shipped with RHEL.

(some names are consistently obfuscated herein to keep real names confidential)

Unfortunately we can't get StartTLS to work. It always fails:

# /opt/xxxdir/bin/ldapsearch -x -ZZ ldap://ldap-srv01.rz.domain
ldap_start_tls: Connect error (-11)
        additional info: TLS: hostname does not match CN in peer certificate
# /opt/xxxdir/bin/ldapsearch -x -ZZ ldap://ldap.domain
ldap_start_tls: Connect error (-11)
        additional info: TLS: hostname does not match CN in peer certificate

But OpenSSL lists the (IMO correct) hostnames in the server's certificate:

---------------------------------- snip ----------------------------------
        Subject: CN=ldap.domain,OU=xxx,O=xxx,C=DE
[..]
            X509v3 Subject Alternative Name:
                email:certificate@xxx.domain,
                DNS:ldap.domain,
                DNS:ldap-srv01.rz.domain,
                DNS:ldap-srv02.rz.domain
---------------------------------- snip ----------------------------------

Is the hostname check confused by the email in the first subjectAltName 
sequence value?

Ciao, Michael.