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>

Refactor code so that we do not store NULL pointers in array
of in-flight DNS servers.
Reported-By: Josef Bacik <jbacik@fb.com>

	Just "packed" doesn't always pack the way we expect.

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>

	* grub-core/net/bootp.c: Likewise.
	* grub-core/net/dns.c: Likewise.
	* grub-core/net/icmp6.c: Likewise.
	* grub-core/net/net.c: Likewise.

	freeing random buffer on failure.
	* grub-core/net/net.c (grub_net_resolve_address): Likewise.

	none is explicitly specified.

	while reallocating.

	* 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.

	on it.

        * grub-core/commands/setpci.c: Likewise.
        * grub-core/commands/videotest.c: Likewise.
        * grub-core/disk/geli.c: Likewise.
        * grub-core/kern/mm.c: Likewise.
        * grub-core/lib/relocator.c: Likewise.
        * grub-core/loader/efi/appleloader.c: Likewise.
        * grub-core/loader/i386/xnu.c: Likewise.
        * grub-core/loader/ia64/efi/linux.c: Likewise.
        * grub-core/loader/xnu.c: Likewise.
        * grub-core/net/dns.c: Likewise.
        * grub-core/net/net.c: Likewise.
        * grub-core/script/lexer.c: Likewise.
        * grub-core/script/parser.y: Likewise.
        * grub-core/script/yylex.l: Likewise.
        * util/getroot.c: Likewise.
        * util/grub-setup.c: Likewise.