[SR-Users] can't assign values to $fU

Henning Westerholt hw at kamailio.org
Wed Jun 13 20:39:09 CEST 2018


Am Mittwoch, 13. Juni 2018, 20:28:13 CEST schrieb Alex Balashov:
> On Wed, Jun 13, 2018 at 01:26:07PM -0500, Karthik Srinivasan wrote:
> > Could you explain why we need to call this function when manipulating $fU
> > ?
> 
> Some PV manipulations work that way, others don't. :-) "Because
> Kamailio".

Don't want to dig into to much technical details here..

But to give a bit more context, the Kamailio architecture related to SIP 
message processing is optimized to avoid re-parsing of the message during 
configuration processing. This works with so called "lumps" which are more or 
less like a programming patch file (e.g. change, delete parts). This lumps are 
applied shortly before sending the message out or if you call 
msg_apply_changes().

Some parts of the SIP message are accessed directly, because they are "more 
important" (like the request URI) are handled specially, some like the From 
user are done like a normal SIP header part as described above.

For a bit more details and to look into the details, have a look to the 
dbg_sip_msg([log_level], [facility]) function in the debugger module.

Best regards,

Henning




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