static void search_callback(void *arg, int status, unsigned char *abuf,
int alen)
{
struct search_query *squery = (struct search_query *) arg;
ares_channel channel = squery->channel;
char *s;
/* Stop searching unless we got a non-fatal error. */
if (status != ARES_ENODATA && status != ARES_ESERVFAIL
&& status != ARES_ENOTFOUND)
end_squery(squery, status, abuf, alen);
else
{
/* Save the status if we were trying as-is. */
if (squery->trying_as_is)
squery->status_as_is = status;
if (squery->next_domain < channel->ndomains)
{
/* Try the next domain. */
status = cat_domain(squery->name,
channel->domains[squery->next_domain], &s);
if (status != ARES_SUCCESS)
end_squery(squery, status, NULL, 0);
else
{
squery->trying_as_is = 0;
squery->next_domain++;
ares_query(channel, s, squery->dnsclass, squery->type,
search_callback, squery);
free(s);
}
}
else if (squery->status_as_is == -1)
{
/* Try the name as-is at the end. */
squery->trying_as_is = 1;
ares_query(channel, squery->name, squery->dnsclass, squery->type,
search_callback, squery);
}
else
end_squery(squery, squery->status_as_is, NULL, 0);
}
}
void ares_search(ares_channel channel, const char *name, int dnsclass,
int type, ares_callback callback, void *arg)
{
struct search_query *squery;
char *s;
const char *p;
int status, ndots;
/* If name only yields one domain to search, then we don't have
* to keep extra state, so just do an ares_query().
*/
status = single_domain(channel, name, &s);
if (status != ARES_SUCCESS)
{
callback(arg, status, NULL, 0);
return;
}
if (s)
{
ares_query(channel, s, dnsclass, type, callback, arg);
free(s);
return;
}
/* Allocate a search_query structure to hold the state necessary for
* doing multiple lookups.
*/
squery = malloc(sizeof(struct search_query));
if (!squery)
{
callback(arg, ARES_ENOMEM, NULL, 0);
return;
}
squery->channel = channel;
squery->name = strdup(name);
if (!squery->name)
{
free(squery);
callback(arg, ARES_ENOMEM, NULL, 0);
return;
}
squery->dnsclass = dnsclass;
squery->type = type;
squery->status_as_is = -1;
squery->callback = callback;
squery->arg = arg;
/* Count the number of dots in name. */
ndots = 0;
for (p = name; *p; p++)
{
if (*p == '.')
ndots++;
}
/* If ndots is at least the channel ndots threshold (usually 1),
* then we try the name as-is first. Otherwise, we try the name
* as-is last.
*/
if (ndots >= channel->ndots)
{
/* Try the name as-is first. */
squery->next_domain = 0;
squery->trying_as_is = 1;
ares_query(channel, name, dnsclass, type, search_callback, squery);
}
else
{
/* Try the name as-is last; start with the first search domain. */
squery->next_domain = 1;
squery->trying_as_is = 0;
status = cat_domain(name, channel->domains[0], &s);
if (status == ARES_SUCCESS)
{
ares_query(channel, s, dnsclass, type, search_callback, squery);
free(s);
}
else
{
free(squery->name);
free(squery);
callback(arg, status, NULL, 0);
}
}
}
static void search_callback(void *arg, int status, int timeouts,
unsigned char *abuf, int alen)
{
struct search_query *squery = (struct search_query *) arg;
ares_channel channel = squery->channel;
char *s;
squery->timeouts += timeouts;
/* Stop searching unless we got a non-fatal error. */
if (status != ARES_ENODATA && status != ARES_ESERVFAIL
&& status != ARES_ENOTFOUND)
end_squery(squery, status, abuf, alen);
else
{
/* Save the status if we were trying as-is. */
if (squery->trying_as_is)
squery->status_as_is = status;
/*
* If we ever get ARES_ENODATA along the way, record that; if the search
* should run to the very end and we got at least one ARES_ENODATA,
* then callers like ares_gethostbyname() may want to try a T_A search
* even if the last domain we queried for T_AAAA resource records
* returned ARES_ENOTFOUND.
*/
if (status == ARES_ENODATA)
squery->ever_got_nodata = 1;
if (squery->next_domain < channel->ndomains)
{
/* Try the next domain. */
status = cat_domain(squery->name,
channel->domains[squery->next_domain], &s);
if (status != ARES_SUCCESS)
end_squery(squery, status, NULL, 0);
else
{
squery->trying_as_is = 0;
squery->next_domain++;
ares_query(channel, s, squery->dnsclass, squery->type,
search_callback, squery);
free(s);
}
}
else if (squery->status_as_is == -1)
{
/* Try the name as-is at the end. */
squery->trying_as_is = 1;
ares_query(channel, squery->name, squery->dnsclass, squery->type,
search_callback, squery);
}
else {
if (squery->status_as_is == ARES_ENOTFOUND && squery->ever_got_nodata) {
end_squery(squery, ARES_ENODATA, NULL, 0);
}
else
end_squery(squery, squery->status_as_is, NULL, 0);
}
}
}
