Appears to be a duplicate, a reply was sent out to the original:
https://lists.haxx.se/pipermail/c-ares/2022-April/000035.html
On 5/2/22 8:08 PM, Dmitry Karpov via c-ares wrote:
Hi,
I recently stepped on an issue with curl using c-ares
ares_getaddrinfo() with PF_UNSPEC family, when AAAA response from DNS
server contained some bad data resulting into ARES_EBADRESP status
code whereas A response was good.
The problem was that when AAAA response was the last received, it made
c-ares to ignore previously received good A response and fail the host
resolution with ARES_EBADRESP status code.
But if A response was the last received, then c-ares ignored the bad
AAAA response and the host resolution was successful.
I looked at the c-ares code, and found the problem in the
host_callback() function (src\lib\ares_getaddrinfo.c: 528)
static void host_callback(void *arg, int status, int timeouts,
unsigned char *abuf, int alen)
{
struct host_query *hquery = (struct host_query*)arg;
int addinfostatus = ARES_SUCCESS;
hquery->timeouts += timeouts;
hquery->remaining--;
if (status == ARES_SUCCESS)
{
addinfostatus = ares__parse_into_addrinfo(abuf, alen, 1,
hquery->port, hquery->ai);
}
if (!hquery->remaining)
{
if (addinfostatus != ARES_SUCCESS && addinfostatus != ARES_ENODATA)
{
/* error in parsing result e.g. no memory */
end_hquery(hquery, addinfostatus);
}
else if (hquery->ai->nodes)
…
When there are no remaining queries, the ARES_EBADRESP parsing error
is reported immediately, even though the previous query might be
successful.
I suggest the following fix for this problem:
if (!hquery->remaining)
{
if (addinfostatus != ARES_SUCCESS && addinfostatus != ARES_ENODATA)
{
/* error in parsing result e.g. no memory */
if (addinfostatus == ARES_EBADRESP && hquery->ai->nodes)
{
/* We got a bad response from the server, but at least
one query
* ended with ARES_SUCCESS */
end_hquery(hquery, ARES_SUCCESS);
}
else
{
end_hquery(hquery, addinfostatus);
}
}
I am also attaching a patch file with the potential fix.
Thanks,
Dmitry Karpov
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