[Devel] OpenSER Dialog Module Improvements

[Tavis P.]

We've been doing some work on the Dialog module and we've discovered a
few strange pieces of logic

The purpose of this email is simply to engage dialog about the dialog
module, perhaps someone is already working on these things



1.  The RFC3261 dialog matching mode

    The dialog module supports a dialog matching mode based off of the
CALL-ID, From Tag and To Tag however this mode is dependent on the
existence of a record from tag (append_fromtag RR module parameter)
    This is needed because the dialog module calls the "is_direction" RR
function which is dependent on the RR fromtag to determine direction
    So, in essence, both dialog matching mode 0 and mode 2 are the same.
(since they are both dependent on a record route parameter)


2.  The dialog storage structure is linked list based instead of a hash
table

    I was a little surprised to discover that the structure used to
store active dialogs is linked list based, meaning its 0(N) instead of 0(1)