The query set documentation states that upon completion queries can be
retrieved for the lifetime of the query set. This is a reasonable
expectation but does not currently occur. This was originally done
to resolve a circular reference between queries and query sets, but
in practice the query can be kept.
This change makes it so a query does not have a reference to the
query set until it begins resolving. It also makes it so that the
reference is given up upon the query being completed. This allows
the queries to remain for the lifetime of the query set. As the
query set on the query is only useful to the query set functionality
and only for the lifetime that the query is resolving this is safe
to do.
ASTERISK-24994 #close
Reported by: Joshua Colp
Change-Id: I54e09c0cb45475896654e7835394524e816d1aa0
This change adds the following:
1. A query set implementation. This is an API that allows queries to be executed in parallel and once all have completed a callback is invoked.
2. Unit tests for the query set implementation.
3. An external PJSIP resolver which uses the DNS core API to do NAPTR, SRV, AAAA, and A lookups.
For the resolver it will do NAPTR, SRV, and AAAA/A lookups in parallel. If NAPTR or SRV
are available it will then do more queries. And so on. Preference is NAPTR > SRV > AAAA/A,
with IPv6 preferred over IPv4. For transport it will prefer TLS > TCP > UDP if no explicit
transport has been provided. Configured transports on the system are taken into account to
eliminate resolved addresses which have no hope of completing.
ASTERISK-24947 #close
Reported by: Joshua Colp
Change-Id: I56cb03ce4f9d3d600776f36928e0b3e379b5d71e
