LDAP搜索ContextCSN

Question

Good evening, I'm relatively new to go and try to write a function exporting the contextCSN variable from an openldap directory (analogous to ldapsearch -x -s base contextCSN) From the documentation of ldap.v2 I came up with this:

searchRequest := ldap.NewSearchRequest(
  baseDN, // The base dn to search
  ldap.ScopeBaseObject, ldap.NeverDerefAliases, 0, 0, false,
  "(contextCSN)", // The filter to apply
  []string{"contextCSN"},     // A list attributes to retrieve
  nil,
)

But it doesn't accept contextCSN as search term

LDAP Result Code 201 "Filter Compile Error": ldap: error parsing filter
exit status 1

Is there a way to query for this value without invoking ldapsearch?

Update: After staring at the output of ldapsearch for a while I came up with this, which did solve the problem. The data is a bit ugly structured but otherwise provides what I needed:

l, err := ldap.DialTLS("tcp", ldapHost, conf)
if err != nil {
    log.Fatal(err)
}
defer l.Close()

searchRequest := ldap.NewSearchRequest(
    baseDN, // The base dn to search
    ldap.ScopeBaseObject, ldap.NeverDerefAliases, 0, 0, false,
    "(objectClass=*)",      // The filter to apply
    []string{"contextCSN"}, // A list attributes to retrieve
    nil,
)

sr, err := l.Search(searchRequest)
if err != nil {
    log.Fatal(err)
}

for _, entry := range sr.Entries {
    for _, csn := range entry.GetAttributeValues("contextCSN") {
        ...
    }
}

Answer 1

(contextCSN) is not a filter, it should be something like (sn=%s) which you want to query

Leave it empty or change your filter as it suits you