[ldns-users] How to use _searchlist provided by ldns_struct_resolver?
Zbynek Michl
zbynek.michl at nic.cz
Mon Oct 25 13:16:44 UTC 2010
Ok, I know that I am a little bit confusing :)
I have my own search function as follows:
---CODE---
ldns_pkt* ds_resolver_search(const ldns_resolver *r, const ldns_rdf *name,
ldns_rr_type t, ldns_rr_class c, uint16_t flags) {
ldns_rdf *new_name;
ldns_rdf **search_list;
size_t i;
ldns_pkt *orig_p, *new_p;
orig_p = NULL;
new_p = NULL;
if (ldns_dname_label_count(name) > 1 ||
(t != LDNS_RR_TYPE_A && t != LDNS_RR_TYPE_AAAA)) { /* query as is */
orig_p = ds_resolver_search_query(r, name, t, c, flags);
if (orig_p && ldns_pkt_get_rcode(orig_p) == LDNS_RCODE_NOERROR) {
return orig_p;
}
}
if (ldns_resolver_dnsrch(r)) { /* query using search-list */
search_list = ldns_resolver_searchlist(r);
for (i = 0; i < ldns_resolver_searchlist_count(r); i++) {
new_name = ldns_dname_cat_clone(name, search_list[i]);
new_p = ds_resolver_search_query(r, new_name, t, c, flags);
ldns_rdf_free(new_name);
if (new_p) {
if (ldns_pkt_get_rcode(new_p) == LDNS_RCODE_NOERROR) {
ldns_pkt_free(orig_p);
return new_p;
} else {
ldns_pkt_free(new_p);
}
}
}
}
return orig_p;
}
---/CODE---
Now I can resolve FQDN names on my own, but default "." in search list results
in A/AAAA queries even for domain names with just one label.
So I suggest to modify ldns_resolver_search() function according to my function
(which then I can use) and remove default "." from the search list.
Thanks,
Zbynek
On 25.10.2010 14:00, Matthijs Mekking wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Hi,
>
> You requested:
> "So I would expect ldns_resolver_search() should try every combination
> for given name (with and without suffix(es))."
>
> Adding the root zone to the search list ensures that every combination
> is tried (all search domains appended or treat it as a fqdn).
>
> But now, if I understand correctly, you want to be able to choose
> whether you should do a fqdn query or append a search domain?
>
> Best regards,
>
> Matthijs
>
>
>
> On 10/25/2010 01:45 PM, Zbynek Michl wrote:
>> Hi Matthijs,
>>
>> thanks for your fixes, however I think that it is not a good idea to add
>> "." zone to the end of the search list in ldns_resolver_new_frm_fp_l()
>> by default.
>>
>> In my case I am querying for A/AAAA records and it does not make a sense
>> to query domain names with just one label (e.g. myname.)
>>
>> It would be better to make new resolver option for this or let user to
>> add it by hand if he needs it (as it was in previous releases of ldns).
>>
>> Regards,
>> Zbynek
>>
>> On 18.10.2010 13:11, Matthijs Mekking wrote:
>> Hi Zbynek,
>>
>> On 10/15/2010 03:01 PM, Zbynek Michl wrote:
>> ...
>>>>> So I would expect ldns_resolver_search() should try every combination
>>>>> for given name (with and without suffix(es)).
>>
>> I guess by default adding the root domain (".") to the search list would
>> fix that.
>>
>>>>> Btw reading of searchlist from resolv.conf containing more than one
>>>>> suffix (e.g. search mydomain.com mydomain.cz) still does not work
>>>>> properly.
>>
>> Fixed this in r3357.
>>
>> Best regards,
>> Matthijs
>>
>>>>>
>>>>> Thanks,
>>>>> Zbynek
>>>>>
>>>>> On 20.9.2010 12:40, Matthijs Mekking wrote:
>>>>> Hi Zbynek,
>>>>>
>>>>> I noticed that the dname2str function prints a dot after every label.
>>>>> And that function is used in ldns_resolver_search(...) to determine if
>>>>> the domain is a relative or a fqdn. I fixed this in trunk, r3347.
>>>>>
>>>>> I found another bug in the ldns_resolver_search function. The
>>>>> ldns_resolver stops as soon it founds a packet. But it would be nice if
>>>>> the ldns_resolver continues its search if the RCODE of that packet is
>>>>> not NOERROR. This fix is in trunk since r3349.
>>>>>
>>>>> Thanks for your report.
>>>>>
>>>>> Best regards,
>>>>>
>>>>> Matthijs
>>>>>
>>>>>
>>>>> On 09/14/2010 06:46 PM, Zbynek Michl wrote:
>>>>>>>> Hi Matthijs,
>>>>>>>>
>>>>>>>> I have tried to make a dname like this:
>>>>>>>>
>>>>>>>> domain = ldns_dname_new_frm_str("myhostname");
>>>>>>>> new_domain = ldns_dname_new_frm_data(ldns_rdf_size(domain) - 1,
>>>>>>>> ldns_rdf_data(domain));
>>>>>>>> printf("domain: %s\n", ldns_rdf2str(domain));
>>>>>>>> printf("new_domain: %s\n", ldns_rdf2str(new_domain));
>>>>>>>>
>>>>>>>> It is strange for me that both printf()s print the same result
>>>>>>>> (with dot
>>>>>>>> at the end). And then when I use:
>>>>>>>>
>>>>>>>> p = ldns_resolver_search(res, new_domain, LDNS_RR_TYPE_A,
>>>>>>>> LDNS_RR_CLASS_IN, LDNS_RD);
>>>>>>>>
>>>>>>>> resolver returns FORMERR, because ldns_resolver_search() uses
>>>>>>>> ldns_rdf2str() which causes to call ldns_resolver_query() with
>>>>>>>> incorrect
>>>>>>>> domain name.
>>>>>>>>
>>>>>>>>
>>>>>>>> Another error of ldns_resolver_search() is that it does not check
>>>>>>>> RCODE.
>>>>>>>> In case of this resolv.conf:
>>>>>>>>
>>>>>>>> search mydomain.com
>>>>>>>> search mydomain.cz
>>>>>>>>
>>>>>>>> and query for "myhostname" will try just first search value even if
>>>>>>>> NXDOMAIN is returned.
>>>>>>>>
>>>>>>>> Last error that I have observed is that ldns_resolver_new_frm_file()
>>>>>>>> reads just first domain name on line, so this searchlist
>>>>>>>> definition is
>>>>>>>> not read completely:
>>>>>>>>
>>>>>>>> search mydomain.com mydomain.cz
>>>>>>>>
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>> Zbynek
>>>>>>>>
>>>>>>>> On 12.5.2010 09:04, Matthijs Mekking wrote:
>>>>>>>> Hi Zbynek,
>>>>>>>>
>>>>>>>> Sorry for the late follow-up. You are right that making a dname from
>>>>>>>> string always returns an absolute dname. You can try making a
>>>>>>>> dname with
>>>>>>>> ldns_dname_new_frm_data().
>>>>>>>>
>>>>>>>> Best regards,
>>>>>>>>
>>>>>>>> Matthijs
>>>>>>>>
>>>>>>>> Zbynek Michl wrote:
>>>>>>>>>>> Hello,
>>>>>>>>>>>
>>>>>>>>>>> I am trying to use search list, but unsuccessfully. Here is an
>>>>>>>>>>> sample:
>>>>>>>>>>>
>>>>>>>>>>> --- CODE ---
>>>>>>>>>>> ldns_rdf *domain = ldns_dname_new_frm_str("myhostname");
>>>>>>>>>>> ldns_rdf *search = ldns_dname_new_frm_str("mydomain.cz");
>>>>>>>>>>>
>>>>>>>>>>> ldns_resolver_push_searchlist(res, search);
>>>>>>>>>>>
>>>>>>>>>>> p = ldns_resolver_search(res, domain, LDNS_RR_TYPE_A,
>>>>>>>>>>> LDNS_RR_CLASS_IN, LDNS_RD);
>>>>>>>>>>> --- /CODE ---
>>>>>>>>>>>
>>>>>>>>>>> The problem is that "myhostname.mydomain.cz" will never be tried,
>>>>>>>>>>> because of ldns_dname_new_frm_str() adds "." to the end of
>>>>>>>>>>> "myhostname"
>>>>>>>>>>> and therefore ldns_resolver_search() will not concatenate
>>>>>>>>>>> "mydomain.cz".
>>>>>>>>>>> So how can I create "myhostname" RDF without trailing "."? Or any
>>>>>>>>>>> other
>>>>>>>>>>> suggestion?
>>>>>>>>>>>
>>>>>>>>>>> Cheers,
>>>>>>>>>>> Zbynek
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> ldns-users mailing list
>>>>>>>>>>> ldns-users at open.nlnetlabs.nl
>>>>>>>>>>> http://open.nlnetlabs.nl/mailman/listinfo/ldns-users
>>>>>>>>
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