Re: [SR-Users] dmq_is_from_node() issue

Hi Charles,

Thanks for the information, I was intending to use dmq_is_from_node as a security check to ensure that the dmq message arrived from a node that it saw as part of the notification address list (excluding itself of course).

I see that it is not intended to be used this way. I'll build on your snippet along with ipops to check these messages.

Thanks again.

On 22/07/2015 15:46, Charles Chance wrote:

Hi,

This is expected. The point of DMQ is to enable dynamic scaling without having to define every node in advance in Kamailio config.

You should not use dmq_is_from_node() with dmq_handle_message() - it is not intended to be a security check for KDMQ messages, but for other messages replicated directly in your config (e.g. REGISTER).

For KDMQ, you should listen on a dedicated IP and/or port and lock down at network/firewall level. Then your DMQ handling block should look something like:

    if (method == "KDMQ") {
            if ($Rp == 5070) {
                    dmq_handle_message();
            } else {
                    drop;
            }
    }

Do this help? Or is there something else you're looking to achieve?

Cheers, Charles

On 22 July 2015 at 15:22, Asgaroth <00asgaroth00@gmail.com mailto:00asgaroth00@gmail.com> wrote:

Hi All,

I have an issue with the dmq_is_from_node() function, whereby it
does not detect a node is on the bus if it has been removed from
its "table" due to previously failed, i presume, ping requests.

I have the following snippet in my main routing block:

if(is_method("KDMQ")) {
        if (dmq_is_from_node()) {
            dmq_handle_message();
            exit;
        } else {
            xlog("L_INFO", "KDMQ message recieved from node not on
our bus!! ($si:$sp) Dropping.");
            exit;
        }
    }

I have the following dmq module parameters enabled for dmq:

modparam("dmq", "server_address", DMQ_ADDRESS)
modparam("dmq", "notification_address", "sip:lb.domain.com:5060
<http://lb.domain.com:5060>")
modparam("dmq", "multi_notify", 1)
modparam("dmq", "num_workers", 4)

DMQ_ADDRESS is set to each of the addresses in the lb.domain.com
<http://lb.domain.com> for each local kamailio instance

lb.domain.com <http://lb.domain.com> resolves to the following
addresses:
    10.6.0.109
    10.6.0.110
    10.6.0.111

If I start up the 1st instance of kamailio and do not start the
other 2 within the default ping timout then I get the expected log
message of dmq removing the nodes from its table, for example:

kamailio[26657]: ERROR: dmq [notification_peer.c:588]:
notification_resp_callback_f(): deleting server
sip:10.6.0.111:5060 <http://10.6.0.111:5060> because of failed request
kamailio[26657]: ERROR: dmq [notification_peer.c:588]:
notification_resp_callback_f(): deleting server
sip:10.6.0.110:5060 <http://10.6.0.110:5060> because of failed request

However, if I then start one, or both, of the other nodes, then
the KDMQ requests are dropped due to my snippet above, I presume,
because dmq_is_from_node() checks its "active" table. See messages
below as an example of the above snippet in action:

kamailio[26656]: INFO: <script>: KDMQ message recieved from node
not on our bus!! (10.6.0.110:5060 <http://10.6.0.110:5060>) Dropping.
kamailio[26656]: INFO: <script>: KDMQ message recieved from node
not on our bus!! (10.6.0.111:5060 <http://10.6.0.111:5060>) Dropping.

Is this expected behaviour from the dmq_is_from_node() function? I
would have expected it to always check the addresses resolved in
the notification address, or am I using this function in a manner
not intended.

Any suggestions/tips would be greatly appreciated.

Thanks


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