[reSIProcate] Dum registration support for mulitple registrations of different usernames

[Shaun Dawson]

All,

I believe that it is currently impossible to use DUM to register more
than one username with a registrar.  This is because of line 17 in
RegistrationCreator.cxx, which uses the target for both the aor and
contact usernames:

   makeInitialRequest(target, target, REGISTER);

I can correct this by changing this line to read:

   makeInitialRequest(target, userProfile->getDefaultFrom(), REGISTER);

which uses the DefaultFrom in the user profile instead of the target.

Two questions:

First, Is this the right way to do this?  It seems like it to me, but
I can't believe that I'm the first person to have encountered this
issue in the Dum.

Second, if this is the right way to do this, does anyone mind if I go
ahead and make this change?  I believe that this will break any
existing implementations that do not properly set up a user profile,
so I'm a little bit afraid of doing that.

thanks,
  Shaun