Re: [SR-Users] GSM PDU Decoding

On 02/04/2014 01:35 AM, Ramya Ramamurthy wrote: Kamailio doesn't care much about the encapsulated message body, and there are no special modules to deal with GSM message bodies. In fact, the only module that I am aware of that deals with manipulation of encapsulated bodies at all (besides the far-end NAT traversal and rtpproxy modules that modify RTP endpoints and other SDP attributes) is the SIP-T module[1]. But that's ISUP, not GSM. You can access the message body with $rb: http://www.kamailio.org/wiki/cookbooks/4.1.x/pseudovariables#rb_-_body_of_r… The bad news is that pretty much all textops[x] functions operate on the RURI or other existing, predefined parts of the SIP message, so you can't use those. Transformations can be of some help: http://www.kamailio.org/wiki/cookbooks/4.1.x/transformations But they mostly expect SIP or URI-like data as well. So, short of cobbling something together with {s.substr}, {s.select} and {re.subst}, those probably aren't going to be very fruitful either. Depending on how complex the GSM PDU is and how exactly it's formatted, you might be better off passing it to a third-party script for processing. Other languages' generally-oriented programming runtimes and libraries allow free reading and manipulation of strings much more easily than Kamailio's relatively narrow config script environment. Offhand, Kamailio supports embedded Lua, Python, Perl, and I think Java and Mono (.NET) as well, although some of these are easier to use than others. All of these modules, as far as I know, involve some performance-related optimisations, such as only loading the language interpreter into memory once, instead of at every invocation. -- Alex [1] http://kamailio.org/docs/modules/4.1.x/modules/sipt.html -- Alex Balashov - Principal Evariste Systems LLC 235 E Ponce de Leon Ave Suite 106 Decatur, GA 30030 United States Tel: +1-678-954-0670 Web: http://www.evaristesys.com/, http://www.alexbalashov.com/