We may get more than one response before exiting out of loop in
grub_net_dns_lookup, but buffer was allocated for the first response only,
so storing answers from subsequent replies wrote past allocated size.
We never really use more than the very first address during lookup so there
is little point in collecting all of them. Just quit early if we already have
some reply.
Code needs serious redesign to actually collect multiple answers
and select the best fit according to requested type (IPv4 or IPv6).
Reported and tested by Michael Chang <mchang@suse.com>
The current logic in the DNS resolution code allocates an address buffer
based on the number of addresses in the response packet. If we receive
multiple response packets in response to a single query packet, this means
that we will reallocate a new buffer large enough for only the addresses in
that specific packet, discarding any previous results in the process. Worse,
we still keep track of the *total* number of addresses resolved in response
to this query, not merely the number in the packet being currently processed.
Use realloc() rather than malloc() to avoid overwriting the existing data,
and allocate a buffer large enough for the total set of addresses rather
than merely the number in this specific response.
We were resetting nb->data every time we tried a new server, but we need to do
it every time we try for a different record, otherwise we don't end up falling
back to the A record properly. Thanks,
Signed-off-by: Josef Bacik <jbacik@fb.com>
Adding multiple questions on a single DNS query is not supportted by
most DNS servers. This patch issues two separate DNS queries
sequentially for ipv4 and then for ipv6.
Fixes: https://savannah.gnu.org/bugs/?39710
* grub-core/net/bootp.c (parse_dhcp_vendor): Add DNS option.
* grub-core/net/dns.c (grub_dns_qtype_id): New enum.
* (grub_net_dns_lookup): Now using separated dns packages.
* (grub_cmd_nslookup): Add error condition.
* (grub_cmd_list_dns): Print DNS option.
* (grub_cmd_add_dns): Add four parameters: --only-ipv4,
* --only-ipv6, --prefer-ipv4, and --prefer-ipv6.
* include/grub/net.h (grub_dns_option_t): New enum.
* (grub_net_network_level_address): option added.
Also-by: Paulo Flabiano Smorigo <pfsmorigo@br.ibm.com>
Signed-off-by: Paulo Flabiano Smorigo <pfsmorigo@br.ibm.com>
* include/grub/net.h (grub_net_poll_cards): New argument stop_condition.
All users updated.
* grub-core/net/arp.c (have_pending): New var.
(pending_req): Likewise.
(grub_net_arp_send_request): Fill pending_req and use have_pending as
stop indicator.
(grub_net_arp_receive): Set have_pending.
* grub-core/net/dns.c (recv_data): New field stop.
(recv_hook): Set stop.
(grub_net_dns_lookup): Init stop and use as stop condition.
* grub-core/net/http.c (http_establish): Use headers_recv as stop
condition.
* grub-core/net/net.c (grub_net_poll_cards): New argument
stop_condition. Stop when it goes true.
* grub-core/net/tcp.c (grub_net_tcp_open): Use `established' as stop
indicator.
* grub-core/net/tftp.c (tftp_open): Use `have_oack' as stop indicator.
