When trying to resolve DNS names into IP addresses, the DNS code fails
from time to time with the following error:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
error: ../../grub-core/net/dns.c:688:no DNS record found.
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
This happens when both IPv4 and IPv6 queries are performed against the
DNS server (e.g. 8.8.8.8) but there is no IP returned for IPv6 query, as
shown below:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
grub> net_del_dns 192.168.122.1
grub> net_add_dns 8.8.8.8
grub> net_nslookup ipv4.test-ipv6.com
error: ../../grub-core/net/dns.c:688:no DNS record found.
grub> net_nslookup ipv4.test-ipv6.com
216.218.228.115
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
The root cause is the code exiting prematurely when the data->addresses
buffer has been allocated in recv_hook(), even if there was no address
returned last time recv_hook() executed.
Signed-off-by: Renaud Métrich <rmetr...@redhat.com>
---
grub-core/net/dns.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
diff --git a/grub-core/net/dns.c b/grub-core/net/dns.c
index 6993a4aba..2dfb98d98 100644
--- a/grub-core/net/dns.c
+++ b/grub-core/net/dns.c
@@ -261,7 +261,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__
((unused)),
/* Code apparently assumed that only one packet is received as response.
We may get multiple responses due to network condition, so check here
and quit early. */
- if (*data->addresses)
+ if (*data->naddresses)
goto out;
head = (struct dns_header *) nb->data;
@@ -305,11 +305,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__
((unused)),
grub_uint32_t ttl = 0;
grub_uint16_t length;
if (ptr >= nb->tail)
- {
- if (!*data->naddresses)
- grub_free (*data->addresses);
- goto out;
- }
+ goto out;
ignored = !check_name (ptr, nb->data, nb->tail, data->name);
while (ptr < nb->tail && !((*ptr & 0xc0) || *ptr == 0))
ptr += *ptr + 1;
@@ -317,11 +313,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__
((unused)),
ptr++;
ptr++;
if (ptr + 10 >= nb->tail)
- {
- if (!*data->naddresses)
- grub_free (*data->addresses);
- goto out;
- }
+ goto out;
if (*ptr++ != 0)
ignored = 1;
class = *ptr++;
@@ -337,11 +329,7 @@ recv_hook (grub_net_udp_socket_t sock __attribute__
((unused)),
length = *ptr++ << 8;
length |= *ptr++;
if (ptr + length > nb->tail)
- {
- if (!*data->naddresses)
- grub_free (*data->addresses);
- goto out;
- }
+ goto out;
if (!ignored)
{
if (ttl_all > ttl)
@@ -429,6 +417,8 @@ recv_hook (grub_net_udp_socket_t sock __attribute__
((unused)),
out:
grub_netbuff_free (nb);
grub_free (redirect_save);
+ if (!*data->naddresses)
+ grub_free (*data->addresses);
return GRUB_ERR_NONE;
}
--
2.40.1
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