====== OpenSER Pseudo-variables for version 1.3.x ======

<code>
Authors of initial tutorial:
Elena-Ramona Modroiu
  <ramona (at) rosdev.ro>
Bogdan-Andrei Iancu
  <bogdan (at) voice-system.ro>
Daniel-Constantin Mierla
  <miconda (at) gmail.com>
</code>

===== Introduction =====


The term “pseudo-variable” is used for special tokens that can be given as parameters to different script functions and they will be replaced with a value before the execution of the function.

The beginning of a “pseudo-variable” is marked by the character “$”. If you want to have the character “$” just double it “$$”.

There is a set of predefined pseudo-variables, which have the name composed from one to three letters, and special pseudo-variables that are references to dynamic fields (AVP and Headers)

===== Pseudo-variables usage =====


Pseudo-variables can be used with many modules of OpenSER, among them:

* acc
* avpops
* textops
* uac
* xlog 

===== The list of pseudo-variables in OpenSER =====


Predefined pseudo-variables are listed in alphabetical order.

==== Pseudo-variable marker ====

**$$** - represents the character '$'

==== URI in SIP Request's P-Asserted-Identity header ====

**$ai** - reference to URI in request's P-Asserted-Identity header (see RFC 3325)

==== Auth Digest URI

**$adu** - URI from Authorization or Proxy-Authorization header. This URI is used when calculating the HTTP Digest Response.

==== Auth realm ====

**$ar** - realm from Authorization or Proxy-Authorization header

==== Auth username ====

**$au** - username from Authorization or Proxy-Authorization header

==== Auth whole username ====

**$aU** - whole username from Authorization or Proxy-Authorization header

==== Request's first branch ====

**$br** - reference to request's first branch

==== Request's all branches ====

**$bR** - reference to request's all branches

==== Branch flags ====

**$bf** - reference to branch flags of branch 0 (RURI) - decimal output


==== Branch flags ====

**$bF** - reference to branch flags of branch 0 (RURI) - hexa output

==== Call-Id ====

**$ci** - reference to body of call-id header

==== Content-Length ====

**$cl** - reference to body of content-length header

==== CSeq ====

**$cs** - reference to body of cseq header

==== Contact header ====

**$ct** - reference to body of contact header


==== Content-Type ====

**$cT** - reference to body of content-type header

==== Domain of destination URI ====

**$dd** - reference to domain of destination uri

==== Diversion header URI ====

**$di** - reference to Diversion header URI

==== Port of destination URI ====

**$dp** - reference to port of destination uri

==== Transport protocol of destination URI ====

**$dP** - reference to transport protocol of destination uri

==== Destination set ====

**$ds** - reference to destination set

==== Destination URI ====

**$du** - reference to destination uri
If loose_route() returns TRUE a destination uri is set according to the first Route header.
$du is also set if lookup() function of 'registrar' module finds contact(s) behind NAT.
To reset $du:
  $du = null;

==== Error class ====

**$err.class** - the class of error (now is '1' for parsing errors)

==== Error level ====

**$err.level** - severity level for the error

==== Error info ====

**$err.info** - text describing the error

==== Error reply code ====

**$err.rcode** - recommended reply code

==== Error reply reason ====

**$err.rreason** - recommended reply reason phrase

==== From URI domain ====

**$fd** - reference to domain in URI of 'From' header

==== From display name ====

**$fn** - reference to display name of 'From' header

==== From tag ====

**$ft** - reference to tag parameter of 'From' header

==== From URI ====

**$fu** - reference to URI of 'From' header

==== From URI username ====

**$fU** - reference to username in URI of 'From' header

==== SIP message buffer ====

**$mb** - reference to SIP message buffer


==== Flags ====

**$mf** - reference to message/transaction flags set for current SIP request


==== Flags in hexadecimal ====

**$mF** -reference to message/transaction flags set for current SIP request in hexa

==== SIP message id ====

**$mi** - reference to SIP message id

==== SIP message length ====

**$ml** - reference to SIP message length

==== Domain in SIP Request's original URI ====

**$od** - reference to domain in request's original URI

==== Port of SIP request's original URI ====

**$op** - reference to port of original R-URI

==== Transport protocol of SIP request original URI ====

**$oP** - reference to transport protocol of original R-URI

==== SIP Request's original URI ====

**$ou** - reference to request's original URI

==== Username in SIP Request's original URI ====

**$oU** - reference to username in request's original URI

==== Domain in SIP Request's P-Preferred-Identity header URI ====

**$pd** - reference to domain in request's P-Preferred-Identity header URI (see RFC 3325)

==== Display Name in SIP Request's P-Preferred-Identity header ====

**$pn** - reference to Display Name in request's P-Preferred-Identity header (see RFC 3325)


==== Process id ====

**$pp** - reference to process id (pid)

==== Transport protocol of received message ====
**$pr** or **$proto** - transport protocol of received message (UDP, TCP, TLS, SCTP (not supported by OpenSER))

==== User in SIP Request's P-Preferred-Identity header URI ====

**$pU** - reference to user in request's P-Preferred-Identity header URI (see RFC 3325)

==== URI in SIP Request's P-Preferred-Identity header ====

**$pu** - reference to URI in request's P-Preferred-Identity header (see RFC 3325)
==== Domain in SIP Request's URI ====

**$rd** - reference to domain in request's URI

<hi #d0d0d0>It is R/W variable (you can assign values to it directly in configuration file)</hi>

==== Body of request/reply ====

**$rb** - reference to message body



==== Returned code ====

**$rc** - reference to returned code by last invoked function

**$retcode** - same as **$rc**

==== Remote-Party-ID header URI ====

**$re** - reference to Remote-Party-ID header URI

==== SIP request's method ====

**$rm** - reference to request's method

==== SIP request's port ====

**$rp** - reference to port of R-URI

==== Transport protocol of SIP request URI ====

**$rP** - reference to transport protocol of R-URI

==== SIP reply's reason ====

**$rr** - reference to reply's reason

==== SIP reply's status ====

**$rs** - reference to reply's status

==== Refer-to URI ====

**$rt** - reference to URI of refer-to header
==== SIP Request's URI ====

**$ru** - reference to request's URI

<hi #d0d0d0>It is R/W variable (you can assign values to it directly in configuration file)</hi>
==== Username in SIP Request's URI ====

**$rU** - reference to username in request's URI

<hi #d0d0d0>It is R/W variable (you can assign values to it directly in configuration file)</hi>

==== Received IP address ====

**$Ri** - reference to IP address of the interface where the request has been received

==== Received port ====

**$Rp** - reference to the port where the message was received

==== Script flags ====

**$sf** - reference to script flags - decimal output


==== Script flags ====

**$sF** - reference to script flags - hexa output

==== IP source address ====

**$si** - reference to IP source address of the message

==== Source port ====

**$sp** - reference to the source port of the message



==== Forced socket ====

**$fs** - reference to the forced socket for message sending (if any) in the form proto:ip:port

==== To URI Domain ====

**$td** - reference to domain in URI of 'To' header

==== To display name ====

**$tn** - reference to display name of 'To' header

==== To tag ====

**$tt** - reference to tag parameter of 'To' header

==== To URI ====

**$tu** - reference to URI of 'To' header

==== To URI Username ====

**$tU** - reference to username in URI of 'To' header

==== String formatted time ====

**$Tf** - reference string formatted time

==== Unix time stamp ====

**$Ts** - reference to unix time stamp

==== User agent header ====

**$ua** - reference to user agent header field

==== AVPs ====

**$(avp(id)[N])** - represents the value of N-th AVP identified by 'id'.

The 'id' can be:

* "[si]:name" - name is the id of an AVP; 's' and 'i' specifies if the id is string or integer. If missing, it is considered to be string.
* "name" - the name is an AVP alias 

**Note:** By default AVP created during initial message is available in “failure_route[]” but not in “onreply_route[]”. To get the last is needed: [[http://www.openser.org/docs/modules/devel/tm.html#AEN304|modparam("tm", "onreply_avp_mode", 1)]]

==== Headers ====


**$(hdr(name)[N])** - represents the body of the N-th header identified by 'name'. If [N] is omitted then the body of the first header is printed. The first header is got when N=0, for the second N=1, a.s.o. To print the last header of that type, use -1, no other negative values are supported now. No white spaces are allowed inside the specifier (before }, before or after {, [, ] symbols). When N='*', all headers of that type are printed.

The module should identify most of compact header names (the ones recognized by OpenSER which should be all at this moment), if not, the compact form has to be specified explicitly. It is recommended to use dedicated specifiers for headers (e.g., %ua for user agent header), if they are available -- they are faster.

==== Script variables ====

**$var(name)** - refers to variables that can be used in configuration script, having integer or string value. This kind of variables are faster the AVPs, being referenced directly to memory location. The value of script variables persists over the processing of SIP messages, being specific per each OpenSER process.

Example of usage:

<code>
$var(a) = 2; -- sets the value of variable 'a' to integer '2'
$var(a) = "2"; -- sets the value of variable 'a' to string '2'
$var(a) = 3 + (7&(~2));
$var(a) = "sip:" + $au + "@" + $fd; -- compose a value from authentication username and From URI domain

if( [ $var(a) & 4 ] ) {
  xlog("var a has third bit set\n");
}
</code>

Setting a variable to null is actually initializing the value to integer '0'. Script variables don't have NULL value.

**Note:** A script variable persists over the OpenSER process in which it was initialized, so be sure of giving it a new value before reading it or you'll get the value asigned in any other previous message processed by the same OpenSER process (pid).


===== Special pseudo-variables in OpenSER - Escape Sequences =====


These pseudo variables are exported, and mainly used, by xlog module to print messages in many colors (foreground and background) using escape sequences. 


==== Foreground and background colors ====


$C(xy) - reference to an escape sequence. “x” represents the foreground color and “y” represents the background color.

Colors could be:

* x : default color of the terminal
* s : Black
* r : Red
* g : Green
* y : Yellow
* b : Blue
* p : Purple
* c : Cyan
* w : White 




===== Examples =====


A few examples of usage.

Example 1. Pseudo-variables usage
<code>
...
avp_aliases="uuid=I:50"
...
route {
...
    $avp(uuid)="caller_id";
    $avp(i:20)= $avp(uuid) + ": " + $fu;
    xdbg("$(C(bg))avp(i:20)$(C(xx)) [$avp(i:20)] $(C(br))cseq$(C(xx))=[$hdr(cseq)]\n");
...
}
...
</code>


===== OpenSER versions =====


This document is valid for following OpenSER versions:

- OpenSER Devel v1.2.0-devX 

===== Pseudo-variables Stuff =====

{{indexmenu>pseudovariables|js}}