Re: libresolv with getaddrinfo

[Joshua Rogers <glibc at internot dot info>]

On 14/03/15 18:47, Joshua Rogers wrote:
> HOwever, on the res_query call on line 46, the _res structure is reset.
>
> If we uncomment L26-28, and comment L34,  res_query correctly uses _res
> with the custom nsaddr, and does NOT reset _res.
>
> So, to me, this seems like a bug in res_init(), not setting something to
> indicate that it indeed has been initialized.. Or that orielly book is
> wrong.
>
> Using the code:
>
>
>         if(_res.options & RES_INIT) {
>                 printf("RES_INIT set.\n");
>         } else {
>                 printf("RES_INIT not set.\n");
>         }
>
> after res_init, indicates RES_INIT is indeed set.
This is incorrect.
_res is not reset.
Or, at least, not completely.

(gdb) n
30       res_init();
(gdb) p _res.options
$1 = 0
(gdb) n
31       _res.options |= (RES_DEBUG|RES_USEVC);
(gdb) p _res.options
$2 = 524993
(gdb) n
32       _res.nscount = 0;
(gdb) p _res.options
$3 = 525003
(gdb) n
35       hp = gethostbyname(argv[1]);
(gdb) n
36       if (!hp) {
(gdb) p _res.options
$4 = 525003


I confirmed (as you can see in the code in the gdb output), that nscount
is reset on the run by gethostbyname, but options is not.

Is this documented behaviour?


Thanks,
-- 
-- Joshua Rogers <https://internot.info/>

Attachment: signature.asc
Description: OpenPGP digital signature