Types of routes

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).

route

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.

branch_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();
        }
    }

failure_route

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");
        }
    }

onreply_route

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");
      }
  }

error_route

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:

$(err.class) - the class of error (now is ‘1’ for parsing errors)
$(err.level) - severity level for the error
$(err.info) - text describing the error
$(err.rcode) - recommended reply code
$(err.rreason) - recommended reply reason phrase

  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;
  }

local_route

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");
     }
  }