[SSSD] [PATCHES] ad srv: prefer servers that are in the same domain as client
Pavel Březina
pbrezina at redhat.com
Thu Aug 8 11:24:17 UTC 2013
On 08/08/2013 03:32 AM, Simo Sorce wrote:
> On Wed, 2013-08-07 at 13:56 +0200, Lukas Slebodnik wrote:
> [..]
> nitpicking some more given Lucas nacked.
>
>>> +static errno_t ad_sort_servers(struct ares_srv_reply **list, void *pvt)
>>> +{
>>> + struct ad_srv_plugin_state *state = NULL;
>>> + struct ares_srv_reply dummy[3] = {{NULL, NULL, 0, 0, 0}};
>
> I think this can be done by simply writing:
>
> struct ares_srv_reply dummy[3] = { 0 };
>
>>> + struct ares_srv_reply *head = &dummy[0];
>>> + struct ares_srv_reply *tail = &dummy[0];
>>> + struct ares_srv_reply *in_head = &dummy[1];
>>> + struct ares_srv_reply *in_tail = &dummy[1];
>>> + struct ares_srv_reply *out_head = &dummy[2];
>>> + struct ares_srv_reply *out_tail = &dummy[2];
>>> + struct ares_srv_reply *cur = NULL;
>>> + struct ares_srv_reply *next = NULL;
>>> + const char *domain = NULL;
>>> + errno_t ret;
>>> +
>>> + if (list == NULL) {
>>> + ret = EINVAL;
>>> + goto done;
>>> + }
>>> +
>>> + if (*list == NULL || (*list)->next == NULL) {
>>> + ret = EOK;
>>> + goto done;
>>> + }
>>> +
>>> + state = talloc_get_type(pvt, struct ad_srv_plugin_state);
>>> + domain = state->discovery_domain;
>>> +
>>> + /* first sort by rfc2782 */
>>> + ret = resolv_sort_srv_reply(list);
>>> + if (ret != EOK) {
>>> + DEBUG(SSSDBG_CRIT_FAILURE, ("resolv_sort_srv_reply() failed "
>>> + "[%d]: %s\n", ret, strerror(ret)));
>>> + goto done;
>>> + }
>>> +
>>> + /* when several servers share priority, prefer the one that is located
>>> + * in the same domain as client (e.g. child domain instead of forest
>>> + * root) */
>>> +
>>> + next = *list;
>>> + do {
>>> + cur = next;
>>> + next = cur->next;
>>> +
>>> + if (is_host_in_domain(cur->host, domain)) {
>>> + in_tail->next = cur;
>>> + in_tail = in_tail->next;
>>> + in_tail->next = NULL;
>>> + } else {
>>> + out_tail->next = cur;
>>> + out_tail = out_tail->next;
>>> + out_tail->next = NULL;
>>> + }
>>> +
>>> + if (next == NULL || cur->priority != next->priority) {
>>> + /* priority has changed or we have reached the end of the srv list,
>>> + * we will merge the lists */
>>> + APPEND_ARES_LIST(tail, in_head, in_tail);
>>> + APPEND_ARES_LIST(tail, out_head, out_tail);
>>> + }
>>> + } while (next != NULL);
>>> +
>>> + *list = head->next;
>>> +
>>> + ret = EOK;
>>> +
>>> +done:
>>> + return ret;
>>> +}
>>
>> I am sorry, but this linked list sorting is not very readable.
>> There is a lot of "struct ares_srv_reply" pointers:
>> head, tail, in_head, in_tail, out_head, out_tail, cur, next
>> I tried to visualize this sorting with pencil and paper, but
>> it was a real mess.
>>
>> I would prefer to:
>> either: use similar approach like in reply_priority_sort
>> from file src/resolv/async_resolv.c (merger-sort)
>> or: don't change this function, but unit test should be written for this
>> function
>
> Why not simply make this a doubly linked list and use the functions in
> src/util/dlinklist.h ?
I'm working with struct ares_srv_reply that comes from ares api.
> Or if you really have to use single linked, maybe add a slinklist.h file
> in util/ that does things as much as possible like dlinklist.h so that
> we use the same style.
Done.
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