[OpenSIPS-Devel] [OpenSIPS/opensips] 1fbe9a: mid_registrar: Fix possible crash on shutdown

[Liviu Chircu]

  Branch: refs/heads/3.0
  Home:   https://github.com/OpenSIPS/opensips
  Commit: 1fbe9a66c57ea35eb73661c528d5a5dbc77f5858
      https://github.com/OpenSIPS/opensips/commit/1fbe9a66c57ea35eb73661c528d5a5dbc77f5858
  Author: Liviu Chircu <liviu at opensips.org>
  Date:   2019-11-13 (Wed, 13 Nov 2019)

  Changed paths:
    M modules/mid_registrar/save.c

  Log Message:
  -----------
  mid_registrar: Fix possible crash on shutdown

Since the TMCB_TRANS_DELETED callback _may get called after_ the module
destroy() phase, the udomain_t structure attached to the callback must
not be accessed anymore if OpenSIPS is shutting down, as the usrloc
module may have already freed most of its data structures.

Fixes #1641