Table of Contents

Kamailio SIP Server v3.2.x: Pseudo-Variables

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 or more characters, and special pseudo-variables that are references to dynamic fields (AVP and Headers).

Pseudo-Variables are implemented by various modules, most of them are provided by pv.

Pseudo-variables usage

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

The list of pseudo-variables

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 user

$au - user part of username from Authorization or Proxy-Authorization header

Auth username domain

$ad - domain part of username from Authorization or Proxy-Authorization header

Auth whole username

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

Acc username

$Au - username for accounting purposes. It's a selective pseudo variable (inherited from acc module). It returns $au if exits or From username otherwise.

Branch attributes

$branch(name) - reference to attribute 'name' of a branch

This pseudo variable gives you access to the “additional branches” only, not to the “main branch”. E.g. if there are 3 clients registered for the same AoR, after lookup() you will have one contact in the “main branch” and two “additional branches”. Using $branch() you can access the additional branches, the main branch can be accessed using $ru and $du. (Note: In branch_routes there is no distinction between the main and the additional branches - the branch_route will be called for all of them.)

The 'name' can be:

The PV can take an index to access a specif branch: $(branch(name)[index])

Example:

$var(i)=0;
while($var(i)<$branch(count))
{
   xlog("$(branch(uri)[$var(i)])\n");
   $var(i) = $var(i) + 1;
}

Starting with 3.1.0, you can assign value per attribute. Index can be used to update a specific branch:

$(branch(attr)[index]) = value;

If index is missing, first branch is used. If index is -1 the last branch is used.

Assigning $null to uri attribute will drop the branch, for the rest of attributes will just set the value to null.

$(branch(uri)[2]) = "sip:test@kamailio.org;transport=sctp";

Request's first branch

$br - reference to request's first branch

It is R/W variable, you can assign values to it directly in configuration file (will add a new 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

Body size

$bs - body size

Call-Id

$ci - reference to body of call-id header

Content-Length

$cl - reference to body of content-length header

CSeq

$cs - reference to the sequence number in the cseq header. The method in the CSeq header is identical to the request method, thus use $rm to get the methode (works also for responses).

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

Diversion "privacy" parameter

$dip - reference to Diversion header “privacy” parameter value

Diversion "reason" parameter

$dir - reference to Diversion header “reason” parameter value

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.

It is R/W variable (you can assign values to it directly in configuration file)

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

It is R/W variable (you can assign values to it directly in configuration file)

Flags in hexadecimal

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

It is R/W variable (you can assign values to it directly in configuration file)

SIP message id

$mi - reference to SIP message id

SIP message length

$ml - reference to SIP message length

SIP Message Type

$mt - returns 1 if the sip message is a request, returns 2 if the sip message is a reply

Domain in SIP Request's original URI

$od - reference to domain in request's original R-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)

Protocol of received message

$pr or $proto - protocol of received message (UDP, TCP, TLS, SCTP)

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

It is R/W variable (you can assign values to it directly in configuration file)

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. Works also for replies (by using the CSeq header)

Request Method ID

$rmid - returns internal integer representation of SIP method type

SIP request's port

$rp - reference to port of R-URI

It is R/W variable (you can assign values to it directly in configuration file)

Transport protocol of SIP request URI

$rP - reference to transport protocol of R-URI

SIP reply's reason (Reason-Phrase)

$rr - reference to reply's reason

SIP reply's status (status-code, response-code, reply-code)

$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

It is R/W variable (you can assign values to it directly in configuration file)

Username in SIP Request's URI

$rU - reference to username in request's URI

It is R/W variable (you can assign values to it directly in configuration file)

URI Scheme of Request URI

$rz - returns R-URI scheme, possible values: sip, sips, tel and tels, R-URI scheme parsing error should be reflected by value: none

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

Statistics

$stat(name) - return the value of statistic item specified by 'name'

Forced socket

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

It is R/W variable (you can assign values to it directly in configuration file)

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

Kamailio startup (boot) timestamp

$Tb - reference to unix timestamp of the time at which kamailio was started

String formatted time - cached

$Tf - reference string formatted time

Note: the system time is retrieved only once for each processed SIP message. Subsequent calls of $Tf for same SIP message will return same value.

String formatted time - current

$TF - reference string formatted time

Note: the system time is computed for each call of $TF. Subsequent calls of $TF for same SIP message may return different values.

Unix time stamp - cached

$Ts - reference to unix time stamp

Note: the system time is retrieved only once for each processed SIP message. Subsequent calls of $Ts for same SIP message will return same value.

Unix time stamp - current

$TS - reference to unix time stamp

Note: the system time is computed for each call of $TS. Subsequent calls of $TS for same SIP message may return different values.

User agent header

$ua - reference to user agent header field

AVPs

$avp(id) - the value of the AVP identified by 'id'.

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

The 'id' can be:

$(avp(id)[0]) can be written in shorter form as $avp(id) and $avp(s:name) as $avp(name).

AVPs are special variables that are attached to SIP transactions. It is a list of pairs (name,value). Before the transaction is created, the AVP list is attached to SIP request. Note that the AVP list works like a stack, last added value is retrieved first, and there can be many values for same AVP name. An assignment to the same AVP name does not overwrite the existing AVP, but it will add an additional AVP to the list. When writing an AVP, the [N] index is ignored, except for [*].

To delete the first AVP with name 'id' you have to assign to it '$null':

$avp(id) = $null;

To delete all the AVP with name 'id' you have to assign $null to the index '*':

$(avp(id)[*]) = $null;

To overwrite the value of the AVP with name 'id' you have to assign the new value to the index '*':

$(avp(id)[*]) = newvalue; # delete all existing AVPs with name 'id' and create a single AVP with newvalue

The value of an AVP can be integer or string. To assign a value as string, it has to be enclosed in double quotes. To assign the value as integer, it has to be a valid number given without quotes.

Example of usage:

$avp(x) = 1;  # assign of integer value
$avp(x) = 2;
$avp(x) = 3;
# now: $avp(x) = $(avp(x)[0]) = 3, $(avp(x)[1]) = 2, $(avp(x)[2]) = 1
$avp(y) = "abc"; # assign of string value
if($(avp(x)[2])==1) { # TRUE
  ...
}
$(avp(x)[1]) = $null; # index will be ignored and top element removed from list
# now: $avp(x) = $(avp(x)[0]) = 2, $(avp(x)[1]) = 1
$(avp(x)[*]) = $null; # all AVPs 'x' are deleted

It is R/W variable (you can assign values to it directly in configuration file).

Headers

$hdr(name) - represents the body of first header identified by 'name'

$(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. In case of a comma-separated multi-body headers, it returns all the bodies, comma-separated. To print the last header of that type, use -1, or other negative values to count from the end. 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 compact header names. It is recommended to use dedicated specifiers for headers (e.g., $ua for user agent header), if they are available – they are faster.

Example of usage:

if($hdr(From)=~"sip-router\.org") {
...
}

It is read-only variable. You can remove or add headers using functions from textops module.

Script private 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 SIP-Router process.

Example of usage:

$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");
}

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 SIP-Router 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 SIP-Router process (pid).

It is R/W variable (you can assign values to it directly in configuration file)

pv module can be used to initialize the script variables.

Script shared variables

$shv(name) - it is a class of pseudo-variables stored in shared memory. The value of $shv(name) is visible across all openser processes. Each “shv” has single value and it is initialised to integer 0. You can use “shvset” parameter of pv module to initialize the shared variable. The module exports a set of MI functions to get/set the value of shared variables.

Example - shv(name) pseudo-variable usage:

...
modparam("pv", "shvset", "debug=i:1")
...
if ($shv(debug) == 1) {
	xlog("request: $rm from $fu to $ru\n");
}
...

It is R/W variable (you can assign values to it directly in configuration file)

Broken-down time

$time(name) - the PV provides access to broken-down time attributes.

The 'name' can be:

Example - time(name) pseudo-variable usage:

...
if ($time(year) == 2008) {
    xlog("request: $rm from $fu to $ru in year 2008\n");
}
...

Strftime Formatted Time

$timef(format) - return current time as formatted by strftime 'format'. See 'man strftime' to see the available time attribute specifiers.

Example:

xlog("Today is $timef(%m/%d/%y)\n");

Selects

$sel(name) - return the value of select specified by name. select refers a class of config variables introduced by SER 2.0, allowing to select and return parts of sip messages and not only.

List of available selects:

Example:

if($sel(via[1].host)=="10.10.10.10")
{
  ...
}

Send Address Attributes

$snd(name) - return attributes of the address from where the request is going to be sent (local socket).

$sndfrom(name) - return attributes of the address from where the request is going to be sent (local socket, same as $snd(name)).

$sndto(name) - return attributes of the address to where the request is going to be sent (remote socket).

They are available in onsend_route. The name can be:

Example:

onsend_route {
  if($snd(ip)=="10.10.10.10")
  {
    ...
  }
}

Dialog module Pseudo-Variables

$dlg(attr)

Return the attribute of the current processed dialog.

It is R/O variable.

The 'attr' can be:

$dlg_ctx(attr)

Return the attribute of the context for current processed dialog.

It is R/W variable.

The 'attr' can be:

HTable module Pseudo-Variables

$sht(htable=>key)

Access hash table entries.

It is R/W variable, you can assign values to it directly in configuration file.

The “htname” must be a hash table name defined via “htable” parameter.

The “key” can be:

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>$au) = 1;
$sht(a=>$ru) = $fu;
...

$shtex(htable=>key)

Access hash table entry expire value. Value represents the seconds until the htable entry will expire and be deleted from htable.

It is R/W variable, you can assign values to it directly in configuration file.

The “htname” must be a hash table name defined via “htable” parameter and have auto-expire greater than 0.

The “key” can be:

...
modparam("htable", "htable", "a=>size=4;autoexpire=120;")
...
$sht(a=>$au) = 1;
$shtex(a=>$au) = 10;
...

$shtcn(htable=>exp)

Count items matching the name by regexp.

The “htname” must be a hash table name defined via “htable” parameter.

The exp can be:

The exp can contain pseudo-variables.

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>abc) = 1;
$shtex(a=>ade) = 10;
xlog("$shtcn(a=>a.*)");
...

$shtcv(htable=>exp)

Count items matching the value by regexp.

The “htname” must be a hash table name defined via “htable” parameter.

The exp must follow same rules as for $shtcn(…).

...
modparam("htable", "htable", "a=>size=4;")
...
$sht(a=>abc) = "xyz";
$shtex(a=>ade) = "xwt";
xlog("$shtcv(a=>x.*)");
...

Memcached module Pseudo-Variables

$mct(key)

Access hash table entries stored in the memcached server.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

...
$mct($au) = 1;
$mct($ru) = $fu;
$mct(test) = 1;
xlog("stored value is $mct(test)");
$mct(test) = null; # delete it
xlog("stored value is $mct(test)"); # will return <null>
...

$mcinc(key)

Do a atomic increment operation on the value stored in memcached. You need to add a value previously.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

...
$mct(cnt) = 1;
$mcinc(cnt) = 2; # increment by 2
xlog("counter is now $mct(cnt)");
...

$mcdec(key)

Do a atomic decrement operation on the value stored in memcached. You need to add a value previously.

It is R/W variable, you can assign values to it directly in configuration file.

The “key” can be:

...
$mct(cnt) = 10;
$mcdec(cnt) = 2; # decrement by 2
xlog("counter is now $mct(cnt)");
...

Presence_xml Pseudo-Variables

$xml(name=>spec)

Example:

$xml(x=>doc) = '<?xml version="1.0" encoding="UTF-8"?><a><b>test</b></a>';
xlog("content of node b: $xml(x=>xpath:/a/b/text())\n");
$xml(x=>xpath:/a/b) = "1234";

TMX module Pseudo-Variables

$T_branch_idx

$T_reply_code

$T_req(pv)

route {
  t_on_reply("1");
  t_relay();
}

onreply_route[1] {
  xlog("Request SRCIP:PORT = $T_req($si):$T_req($sp)\n");
}

$T_rpl(pv)

route {
  t_on_failure("1");
  t_relay();
}

failure_route[1] {
  xlog("Reply SRCIP:PORT = $T_rpl($si):$T_rpl($sp)\n");
}

$T_inv(pv)

route {
  if(is_method("CANCEL"))
  {
     if($T_inv($mf) & 1 )
     {
        # first flag is set in the INVITE transaction
     }
  }
}

$T(name)

The name can be:

Note: the pair (id_index,id_label) uniquely identifies a transaction.

UAC module Pseudo-Variables

$uac_req(key)

key can be:

$uac_req(method)="OPTIONS";
$uac_req(ruri)="sip:kamailio.org";
$uac_req(furi)="sip:kamailio.org";
$uac_req(turi)="sip:kamailio.org";
uac_send_req();

Nathelper module Pseudo-Variables

$rr_count

$rr_top_count

MQueue module Pseudo-Variables

$mqk(q)

$mqv(q)

...
mq_add("myq", "$rU", "call from $fU at $Tf");
...
while(mq_fetch("myq"))
{
   xlog("$mqk(myq) - $mqv(myq)\n");
}
...

TimeVal

$TV(name)

Seconds and microseconds taken from struct timeval.

Next hop address

$nh(key)

Return attributes of next hop for the SIP request. Address is taken from dst_uri, if set, if not from new r-uri or original r-uri.

GeoIP module Pseudo-Variables

$gip(pvc=>key)

Variables exported by GeoIP module, returning geo-location attributes. The attributes are populated upon calling function geoip_match(ipaddr, pvc).

pvc (container id) is second parameter of geoip_match(..) and key can be:

You can call several time geoip_match(ipaddr, pvc) with different ip address and containers in your config, to compare, for example, attributes of source and destination of a call.

geoip_match("$si", "src");
geoip_match("$nh(d)", "dst");
 
if($gip(src=>cc)==$gip(dst=>cc))
{
    # source and destination from same country
}

XHTTP module Pseudo-Variables

$hu

Special pseudo-variables - 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:

Examples

A few examples of usage.

Example 1. Pseudo-variables usage

...
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");
...
}
...