OpenSER - Pseudo-variables

Elena-Ramona Modroiu

Bogdan-Andrei Iancu

Table of Contents

1. Introduction
2. Pseudo-variables usage
3. The list of pseudo-variables in OpenSER
3.1. Pseudo-variable marker
3.2. Auth realm
3.3. Auth username
3.4. Request's first branch
3.5. Request's all branches
3.6. Call-Id
3.7. Content-Length
3.8. CSeq
3.9. Contact header
3.10. Content-Type
3.11. Domain of destination URI
3.12. Port of destination URI
3.13. Transport protocol of destination URI
3.14. Destination set
3.15. Destination URI
3.16. From URI domain
3.17. From tag
3.18. From URI
3.19. From URI username
3.20. SIP message buffer
3.21. Flags
3.22. Flags in hexadecimal
3.23. SIP message id
3.24. SIP message length
3.25. Process id
3.26. Domain in SIP Request's URI
3.27. Body of request/reply
3.28. Returned code
3.29. SIP request's method
3.30. SIP request's port
3.31. Transport protocol of SIP request URI
3.32. SIP reply's reason
3.33. SIP reply's status
3.34. Refer-to URI
3.35. SIP Request's URI
3.36. Username in SIP Request's URI
3.37. Received IP address
3.38. Received port
3.39. IP source address
3.40. Source port
3.41. To URI Domain
3.42. To tag
3.43. To URI
3.44. To URI Username
3.45. String formatted time
3.46. Unix time stamp
3.47. User agent header
3.48. AVPs
3.49. Headers
4. Special pseudo-variables in OpenSER - Escape Sequences
4.1. Foreground and background colors
5. Examples
6. OpenSER versions

1. 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)

2. Pseudo-variables usage

Pseudo-variables can be used with following modules of OpenSER:

  • avpops - function “avp_printf()

  • xlog - functions “xlog()” and “xdbg()

3. The list of pseudo-variables in OpenSER

Predefined pseudo-variables are listed in alphabetical order.

3.1. Pseudo-variable marker

$$ - represents the character '$'

3.2. Auth realm

$ar - realm from Authorization or Proxy-Authorization header

3.3. Auth username

$au - username from Authorization or Proxy-Authorization header

3.4. Request's first branch

$br - reference to request's first branch

3.5. Request's all branches

$bR - reference to request's all branches

3.6. Call-Id

$ci - reference to body of call-id header

3.7. Content-Length

$cl - reference to body of content-length header

3.8. CSeq

$cs - reference to body of cseq header

3.9. Contact header

$ct - reference to body of contact header

3.10. Content-Type

$cT - reference to body of content-type header

3.11. Domain of destination URI

$dd - reference to domain of destination uri

3.12. Port of destination URI

$dp - reference to port of destination uri

3.13. Transport protocol of destination URI

$dP - reference to transport protocol of destination uri

3.14. Destination set

$ds - reference to destination set

3.15. Destination URI

$du - reference to destination uri

3.16. From URI domain

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

3.17. From tag

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

3.18. From URI

$fu - reference to URI of 'From' header

3.19. From URI username

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

3.20. SIP message buffer

$mb - reference to SIP message buffer

3.21. Flags

$mf - reference to flags set for current SIP request

3.22. Flags in hexadecimal

$mF -reference to flags set for current SIP request in hexa

3.23. SIP message id

$mi - reference to SIP message id

3.24. SIP message length

$ml - reference to SIP message length

3.25. Process id

$pp - reference to process id (pid)

3.26. Domain in SIP Request's URI

$rd - reference to domain in request's URI

3.27. Body of request/reply

$rb - reference to message body

3.28. Returned code

$rc - reference to returned code by last invoked function

3.29. SIP request's method

$rm - reference to request's method

3.30. SIP request's port

$rp - reference to port of R-URI

3.31. Transport protocol of SIP request URI

$rP - reference to transport protocol of R-URI

3.32. SIP reply's reason

$rr - reference to reply's reason

3.33. SIP reply's status

$rs - reference to reply's status

3.34. Refer-to URI

$rt - reference to URI of refer-to header

3.35. SIP Request's URI

$ru - reference to request's URI

3.36. Username in SIP Request's URI

$rU - reference to username in request's URI

3.37. Received IP address

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

3.38. Received port

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

3.39. IP source address

$si - reference to IP source address of the message

3.40. Source port

$sp - reference to the source port of the message

3.41. To URI Domain

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

3.42. To tag

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

3.43. To URI

$tu - reference to URI of 'To' header

3.44. To URI Username

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

3.45. String formatted time

$Tf - reference string formatted time

3.46. Unix time stamp

$Ts - reference to unix time stamp

3.47. User agent header

$ua - reference to user agent header field

3.48. 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

3.49. 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.

4. Special pseudo-variables in OpenSER - Escape Sequences

These pseudo variables are used by xlog module to print messages in many colors using escape sequences. The other modules ingnore them or throw error if they met these pseudo-variables.

4.1. Foreground and background colors

$Cxy - 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

5. Examples

A few examples of usage.

Example 1. Pseudo-variables usage

modparam("avpops", "avp_aliases", "uuid=I:50")
route {
    avp_write("caller_id", "$uuid");
    avp_printf("i:20", "$avp($uuid): $fu");
    xdbg("$Cbgi:20$Cxx [$avp(i:20)] $Cbrcseq$Cxx=[$hdr(cseq)]\n");

6. OpenSER versions

This document is valid for following OpenSER versions:

- OpenSER v0.10.0+