[sr-dev] dns_cache_rec_pref not supported in the config file

[smititelu]

Hi,

My name is Stefan and I am a new member of the 1&1 VoIP team.

I have noticed that parsing support is not implemented for the 
dns_cache_rec_pref core parameter although this parameter is documented 
in doc/cfg_list/docbook/cfg_core.xml. Thus, one can not set the 
parameter's value in kamailio config file.

I had noticed the problem due to an an increase in the real_used_size 
memory when "kamctl stats shmem" was issued, after DNS SRV queries were 
made (when SRV are not added manually using kamctl). The SRV (0 ttl) and 
resulting A (3600 ttl) records are added in kamailio's memory even if 
the same entries already exist; the existing entries are _not_ 
overwritten even if they are the same and are kept in memory until the 
ttl expires. This is because dns_cache_rec_pref is 0 by default which 
means that it won't check for duplicates. This can be also seen using 
"kamcmd dns.view" and "kamcmd dns.mem_info".

In my opinion, this core parameter should be supported. We have a little 
patch for this.

I want to ask you if there is an explicit reason for not being 
implemented yet?

Regards,
Stefan