[asterisk-dev] [Code Review] 4474: core: Add basic DNS API implementation

[Joshua Colp]

> On March 16, 2015, 2:55 p.m., Mark Michelson wrote:
> > /trunk/include/asterisk/dns_core.h, line 225
> > <https://reviewboard.asterisk.org/r/4474/diff/3/?file=72477#file72477line225>
> >
> >     First off, apologies for bringing this up now rather than earlier, but I did not think of this until over this past weekend.
> >     
> >     The main reason that ast_dns_resolve_async() returns an ast_dns_query is so that the query can be canceled by calling ast_dns_resolve_cancel(). The problem is that there is nothing that prevents the caller of ast_dns_resolve_async() from doing unwanted operations such as adding DNS results/records, or attempting to read results from the query while an async thread is currently writing them.
> >     
> >     What I propose here is returning something other than an ast_dns_query from this function. The structure returned from ast_dns_resolve_async() could be passed to ast_dns_resolve_cancel(), and that's it. This would be similar to how ast_dns_resolve_recurring() works.
> 
> Joshua Colp wrote:
>     I'm not sure how that would stop the reading of results though. We'd need to add a lock in, which is something I was trying to avoid for the core. How hard do we want to enforce things?
> 
> Mark Michelson wrote:
>     The only way that it would not prevent reading of results is if you included dns_internal.h in your source file. If you don't include dns_internal.h in your source, then you would essentially have an opaque handle that was returned by ast_dns_resolve_async() and could be passed to ast_dns_resolve_cancel().

Oh, I see, yeah.


- Joshua


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On March 16, 2015, 3:26 p.m., Joshua Colp wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviewboard.asterisk.org/r/4474/
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> 
> (Updated March 16, 2015, 3:26 p.m.)
> 
> 
> Review request for Asterisk Developers.
> 
> 
> Bugs: ASTERISK-24834
>     https://issues.asterisk.org/jira/browse/ASTERISK-24834
> 
> 
> Repository: Asterisk
> 
> 
> Description
> -------
> 
> This change implements the basic API as described on the DNS API wiki page. Minimal changes have been made as required based on real usage and getting a feel for it. As it is the core functionality is present. Resolvers can register, queries can be made (async / sync).
> 
> As the API was basically copy/pasted from the wiki page there still remain stubs to be filled in for higher level functionality (such as parsing and query sets).
> 
> 
> Diffs
> -----
> 
>   /trunk/main/dns_tlsa.c PRE-CREATION 
>   /trunk/main/dns_srv.c PRE-CREATION 
>   /trunk/main/dns_recurring.c PRE-CREATION 
>   /trunk/main/dns_query_set.c PRE-CREATION 
>   /trunk/main/dns_naptr.c PRE-CREATION 
>   /trunk/main/dns_core.c PRE-CREATION 
>   /trunk/include/asterisk/dns_tlsa.h PRE-CREATION 
>   /trunk/include/asterisk/dns_srv.h PRE-CREATION 
>   /trunk/include/asterisk/dns_resolver.h PRE-CREATION 
>   /trunk/include/asterisk/dns_recurring.h PRE-CREATION 
>   /trunk/include/asterisk/dns_query_set.h PRE-CREATION 
>   /trunk/include/asterisk/dns_naptr.h PRE-CREATION 
>   /trunk/include/asterisk/dns_internal.h PRE-CREATION 
>   /trunk/include/asterisk/dns_core.h PRE-CREATION 
> 
> Diff: https://reviewboard.asterisk.org/r/4474/diff/
> 
> 
> Testing
> -------
> 
> Ran DNS unit tests as done by Mark, they are happy.
> 
> 
> Thanks,
> 
> Joshua Colp
> 
>

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