Proposition of a network function to sort DNS SRV records

Hello, currently the built-in dns_get_record function has support for type SRV, which is very nice. Yet this supports only part of the DNS SRV RFC (RFC-2782). In particular, it will return records but won't sort them using the weight/priority algorithm. I won't detail the algorithm, but basically the lower priority records must be contacted first. And server with same priority must be contacted in a semi-random order using weight as a probability to be selected first (the larger weight, the larger chance). For instance, if I check Google's DNS records for their XMPP (IM) service: ------------------- $ ring _xmpp-client._tcp.gmail.com gmail.com. has a xmpp-client service record on tcp: priority = 20 weight = 0 port = 5222 target = talk3.l.google.com. gmail.com. has a xmpp-client service record on tcp: priority = 20 weight = 0 port = 5222 target = talk4.l.google.com. gmail.com. has a xmpp-client service record on tcp: priority = 5 weight = 0 port = 5222 target = talk.l.google.com. gmail.com. has a xmpp-client service record on tcp: priority = 20 weight = 0 port = 5222 target = talk1.l.google.com. gmail.com. has a xmpp-client service record on tcp: priority = 20 weight = 0 port = 5222 target = talk2.l.google.com. ------------------- We see here that one should always contact first talk.l.google.com and only if it fails, try the 4 remaining addresses (randomized with equal chances). That's like a basic/static load balancer. Anyway! So a return of dns_get_record would return the records in the order the DNS server responded (which is good and is what is asked: a bare DNS query function). I propose an additional function, called for instance dns_srv_sort which takes the return of dns_get_record, sort it and return sorted server/port data, ready to be connected to in this order. Example: $response = dns_get_record ('_xmpp-client._tcp.gmail.com', DNS_SRV); returns: Array ( [0] => Array ( [host] => _xmpp-client._tcp.gmail.com [type] => SRV [pri] => 20 [weight] => 0 [port] => 5222 [target] => talk1.l.google.com [class] => IN [ttl] => 9564 ) [1] => Array ( [host] => _xmpp-client._tcp.gmail.com [type] => SRV [pri] => 20 [weight] => 0 [port] => 5222 [target] => talk2.l.google.com [class] => IN [ttl] => 9564 ) [2] => Array ( [host] => _xmpp-client._tcp.gmail.com [type] => SRV [pri] => 20 [weight] => 0 [port] => 5222 [target] => talk3.l.google.com [class] => IN [ttl] => 9564 ) [3] => Array ( [host] => _xmpp-client._tcp.gmail.com [type] => SRV [pri] => 20 [weight] => 0 [port] => 5222 [target] => talk4.l.google.com [class] => IN [ttl] => 9564 ) [4] => Array ( [host] => _xmpp-client._tcp.gmail.com [type] => SRV [pri] => 5 [weight] => 0 [port] => 5222 [target] => talk.l.google.com [class] => IN [ttl] => 9564 ) ) $response = dns_srv_sort($response); returns: Array ( [0] => Array ( [port] => 5222 [server] => talk.l.google.com ) [1] => Array ( [port] => 5222 [server] => talk4.l.google.com ) [2] => Array ( [port] => 5222 [server] => talk3.l.google.com ) [3] => Array ( [port] => 5222 [server] => talk2.l.google.com ) [4] => Array ( [port] => 5222 [server] => talk2.l.google.com ) ) So this is a function I have used with success for quite some time. Feel free to check the sorting algorithm against RFC-2782. I think that's quite useful to have this function as a core function because right now, either PHP users will not sort SRV records as imposed by the RFC, or will each time rewrite the sorting function. Also I loaded the source repository and I see most functions are actually developed in C. Is it necessary to do so? If that's a prerequisite and you are actually interested in this function to be inserted as a core function, I will make the rewrite. And finally sorry by advance, I may not be aware of all the right procedure for proposing a patch (anyway that's not yet a patch, just a separate file), though the "Using SVN for PHP development" said to send patch to this ml. I hope that's fine. Thanks! Jehan

Attachment: [application/x-httpd-php] dns_srv_sort.php