upstream/bind9
1
0
Fork 0
mirror of https://github.com/isc-projects/bind9.git synced 2026-04-23 23:28:18 -04:00
Code Issues Projects Releases Packages Wiki Activity Actions

Process NSID and DNS COOKIE options when returning BADVERS

Browse source 
This will help identify the broken server if we happen to break
EDNS version negotiation.  It will also help protect the client
from spoofed BADVERSION responses.

(cherry picked from commit 0d9cab1555)
This commit is contained in:
Mark Andrews 2024-10-25 14:43:03 +11:00
parent 745a9ab15f
commit 71875eb25a
1 changed files with 23 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
lib/ns/client.c
View file

@ -1550,17 +1550,6 @@ process_opt(ns_client_t *client, dns_rdataset_t *opt) {
* XXXRTH need library support for this!
*/
client->ednsversion = (opt->ttl & 0x00FF0000) >> 16;
if (client->ednsversion > DNS_EDNS_VERSION) {
ns_stats_increment(client->manager->sctx->nsstats,
ns_statscounter_badednsver);
result = ns_client_addopt(client, client->message,
&client->opt);
if (result == ISC_R_SUCCESS) {
result = DNS_R_BADVERS;
}
ns_client_error(client, result);
return result;
}
/* Check for NSID request */
result = dns_rdataset_first(opt);
@ -1572,6 +1561,17 @@ process_opt(ns_client_t *client, dns_rdataset_t *opt) {
while (isc_buffer_remaininglength(&optbuf) >= 4) {
optcode = isc_buffer_getuint16(&optbuf);
optlen = isc_buffer_getuint16(&optbuf);
/*
* When returning BADVERSION, only process
* DNS_OPT_NSID or DNS_OPT_COOKIE options.
*/
if (client->ednsversion > DNS_EDNS_VERSION &&
optcode != DNS_OPT_NSID &&
optcode != DNS_OPT_COOKIE)
{
isc_buffer_forward(&optbuf, optlen);
continue;
}
switch (optcode) {
case DNS_OPT_NSID:
if (!WANTNSID(client)) {
@ -1643,6 +1643,18 @@ process_opt(ns_client_t *client, dns_rdataset_t *opt) {
}
}
if (client->ednsversion > DNS_EDNS_VERSION) {
ns_stats_increment(client->manager->sctx->nsstats,
ns_statscounter_badednsver);
result = ns_client_addopt(client, client->message,
&client->opt);
if (result == ISC_R_SUCCESS) {
result = DNS_R_BADVERS;
}
ns_client_error(client, result);
return result;
}
ns_stats_increment(client->manager->sctx->nsstats,
ns_statscounter_edns0in);
client->attributes |= NS_CLIENTATTR_WANTOPT;