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Tweaks to EDNS0 handling in DNS replies.

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This commit is contained in:
Simon Kelley
2015-12-17 10:44:58 +00:00
parent 2dbba34b2c
commit dd4ad9ac7e
2 changed files with 43 additions and 36 deletions
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59
src/rfc1035.c
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@@ -1539,7 +1539,13 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
int nxdomain = 0, auth = 1, trunc = 0, sec_data = 1;
struct mx_srv_record *rec;
size_t len;
if (ntohs(header->ancount) != 0 ||
ntohs(header->nscount) != 0 ||
ntohs(header->qdcount) == 0 ||
OPCODE(header) != QUERY )
return 0;
/* Don't return AD set if checking disabled. */
if (header->hb4 & HB4_CD)
sec_data = 0;
@@ -1548,33 +1554,32 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
*ad_reqd = header->hb4 & HB4_AD;
*do_bit = 0;
/* If there is an RFC2671 pseudoheader then it will be overwritten by
/* If there is an additional data section then it will be overwritten by
partial replies, so we have to do a dry run to see if we can answer
the query. We check to see if the do bit is set, if so we always
forward rather than answering from the cache, which doesn't include
security information, unless we're in DNSSEC validation mode. */
if (find_pseudoheader(header, qlen, NULL, &pheader, NULL))
{
unsigned short flags;
have_pseudoheader = 1;
pheader += 4; /* udp size, ext_rcode */
GETSHORT(flags, pheader);
if ((sec_reqd = flags & 0x8000))
{
*do_bit = 1;/* do bit */
*ad_reqd = 1;
}
the query. */
if (ntohs(header->arcount) != 0)
{
dryrun = 1;
/* If there's an additional section, there might be an EDNS(0) pseudoheader */
if (find_pseudoheader(header, qlen, NULL, &pheader, NULL))
{
unsigned short flags;
have_pseudoheader = 1;
pheader += 4; /* udp size, ext_rcode */
GETSHORT(flags, pheader);
if ((sec_reqd = flags & 0x8000))
{
*do_bit = 1;/* do bit */
*ad_reqd = 1;
}
}
}
if (ntohs(header->qdcount) == 0 || OPCODE(header) != QUERY )
return 0;
for (rec = daemon->mxnames; rec; rec = rec->next)
rec->offset = 0;
@@ -1730,8 +1735,12 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
}
else if ((crecp = cache_find_by_addr(NULL, &addr, now, is_arpa)))
{
/* Don't use cache when DNSSEC data required. */
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || !sec_reqd || !(crecp->flags & F_DNSSECOK))
/* Don't use cache when DNSSEC data required, unless we know that
the zone is unsigned, which implies that we're doing
validation. */
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
!sec_reqd ||
(option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))
{
do
{