512        if (fo_is_srv_lookup(server)) {
At conditional (1): "dns_domain == NULL" taking the true branch.
At conditional (2): "server->srv_data->dns_domain == NULL" taking the false branch.
Comparing "dns_domain" to null implies that "dns_domain" might be null.
Passing null variable "dns_domain" to function "strcasecmp", which dereferences it. (Deref assumed on the basis of 'nonnull' parameter attribute.)
  513            if (((dns_domain == NULL && server->srv_data->dns_domain == NULL) ||
  514                  strcasecmp(server->srv_data->dns_domain, dns_domain) == 0) &&
  515                strcasecmp(server->srv_data->proto, proto) == 0) {
  516                return EEXIST;
  517            }