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| Types of Routes v1.5 |
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OpenSIPS routing logic uses several types of routes. Each type of route is triggered by a certain event and allows you to process a certain type of message (request or reply).
Request routing block. It contains a set of actions to be taken for SIP requests.
Triggered by : receiving an external request from the network.
Processing : the triggering SIP request.
Type : initially stateless, may be forced to stateful by using TM functions.
Default action : if the request is not either forwarded nor replied, the route will simply discard the request at the end.
The main 'route' block identified by 'route{...}' or 'route[0]{...}' is executed for each SIP request.
The implicit action after execution of the main route block is to drop the SIP request. To send a reply or forward the request, explicit actions must be called inside the route block.
Example of usage:
route {
if(is_method("OPTIONS")) {
# send reply for each options request
sl_send_reply("200", "ok");
exit();
}
route(1);
}
route[1] {
# forward according to uri
forward();
}
Note that if a 'route(X)' is called from a 'branch_route[Y]' then in 'route[X]' is just processed each separate branch instead of all branches together as occurs in main route.
Request's branch routing block. It contains a set of actions to be taken for each branch of a SIP request.
Triggered by : preparation a new branch (of a request); the branch is well formed, but not yet sent out.
Processing : the SIP request (with the branch particularities, like RURI, branch flags)
Type : stateful
Default action : if the branch is not dropped (via "drop" statement), the branch will be automatically sent out.
It is executed only by TM module after it was armed via t_on_branch("branch_route_index").
Example of usage:
route {
lookup("location");
t_on_branch("1");
if(!t_relay()) {
sl_send_reply("500", "relaying failed");
}
}
branch_route[1] {
if(uri=~"10\.10\.10].10") {
# discard branches that go to 10.10.10.10
drop();
}
}
Failed transaction routing block. It contains a set of actions to be taken each transaction that received only negative replies (>=300) for all branches.
Triggered by : receiving or generation(internal) of a negative reply that completes the transaction (all branches are terminated with negative replies)
Processing : the original SIP request (that was sent out)
Type : stateful
Default action : if no new branch is generated or no reply is forced over, by default, the winning reply will be sent back to UAC.
The 'failure_route' is executed only by TM module after it was armed via t_on_failure("failure_route_index").
Note that in 'failure_route' is processed the request that initiated the transaction, not the reply .
Example of usage:
route {
lookup("location");
t_on_failure("1");
if(!t_relay()) {
sl_send_reply("500", "relaying failed");
}
}
failure_route[1] {
if(is_method("INVITE")) {
# call failed - relay to voice mail
t_relay("udp:voicemail.server.com:5060");
}
}
Reply routing block. It contains a set of actions to be taken for SIP replies.
Triggered by : receiving of a reply from the network
Processing : the received reply
Type : stateful (if bound to a transaction) or stateless (if global reply route).
Default action : if the reply is not dropped (only provisional replies can be), it will be injected and processed by the transaction engine.
The main 'onreply_route' identified by 'onreply_route {...}' or 'onreply_route[0] {...}' is executed for all replies received.
Certain 'onreply_route' blocks can be executed by TM module for special replies. For this, the 'onreply_route' must be armed for the SIP requests whose replies should be processed within it, via t_on_reply("onreply_route_index").
route {
lookup("location");
t_on_reply("1");
if(!t_relay()) {
sl_send_reply("500", "relaying failed");
}
}
onreply_route[1] {
if(status=~"1[0-9][0-9]") {
log("provisional response\n");
}
}
The error route is executed automatically when a parsing error occurred during SIP request processing. This allow the administrator to decide what to do in case of error.
Triggered by : parsing error in "route"
Processing : failed request
Type : stateless (recommended)
Default action : discard request.
In error_route, the following pseudo-variables are available to get access to error details:
error_route {
xlog("--- error route class=$(err.class) level=$(err.level)
info=$(err.info) rcode=$(err.rcode) rreason=$(err.rreason) ---\n");
xlog("--- error from [$si:$sp]\n+++++\n$mb\n++++\n");
sl_send_reply("$err.rcode", "$err.rreason");
exit;
}
The local route is executed automatically when a new SIP request is generated by TM, internally (no UAC side). This is a route intended to be used for message inspection, accouting and for applying last changes on the message headers. Routing and signalling functions are not allowed.
Triggered by : TM generating a brand new request
Processing : the new request
Type : stateful
Default action : send the request out
local_route {
if (is_method("INVITE") && $ru=~"@foreign.com") {
append_hf("P-hint: foreign request\r\n");
exit;
}
if (is_method("BYE") ) {
acc_log_request("internally generated BYE");
}
}