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Use a simpler arrangement for the all_addr union to avoid

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the compiler padding it with an extra 8 bytes.

Use the F_KEYTAG flag in a a cache record to discriminate between
an arbitrary RR stored entirely in the addr union and one
which has a point to block storage.
This commit is contained in:
Simon Kelley
2023-04-01 21:35:26 +01:00
parent 3a601d06bd
commit a78487a4df
3 changed files with 84 additions and 51 deletions
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67
src/rfc1035.c
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@@ -806,20 +806,20 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
if (!CHECK_LEN(header, p1, qlen, ardlen))
return 2; /* bad packet */
addr.rr.rrtype = aqtype;
/* If the data has no names and is small enough, store it in
the crec address field rather than allocate a block. */
if (*rrdesc == -1 && ardlen <= RR_IMDATALEN)
if (*rrdesc == -1 && ardlen <= (int)RR_IMDATALEN)
{
addr.rr.len = (char)ardlen;
if (ardlen != 0)
memcpy(addr.rr.u.data, p1, ardlen);
addr.rrdata.rrtype = aqtype;
addr.rrdata.datalen = (char)ardlen;
if (ardlen != 0)
memcpy(addr.rrdata.data, p1, ardlen);
}
else
{
addr.rr.len = -1;
addr.rr.u.block.datalen = 0;
addr.rrblock.rrtype = aqtype;
addr.rrblock.datalen = 0;
flags |= F_KEYTAG; /* discriminates between rrdata and rrblock */
/* The RR data may include names, and those names may include
compression, which will be rendered meaningless when
@@ -827,7 +827,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
Here we go through a description of the packet type to
find the names, and extract them to a c-string and then
re-encode them to standalone DNS format without compression. */
if (!(addr.rr.u.block.rrdata = blockdata_alloc(NULL, 0)))
if (!(addr.rrblock.rrdata = blockdata_alloc(NULL, 0)))
return 0;
do
{
@@ -836,9 +836,9 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
if (desc == -1)
{
/* Copy the rest of the RR and end. */
if (!blockdata_expand(addr.rr.u.block.rrdata, addr.rr.u.block.datalen, (char *)p1, endrr - p1))
if (!blockdata_expand(addr.rrblock.rrdata, addr.rrblock.datalen, (char *)p1, endrr - p1))
return 0;
addr.rr.u.block.datalen += endrr - p1;
addr.rrblock.datalen += endrr - p1;
}
else if (desc == 0)
{
@@ -849,18 +849,18 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
return 2;
len = to_wire(name);
if (!blockdata_expand(addr.rr.u.block.rrdata, addr.rr.u.block.datalen, name, len))
if (!blockdata_expand(addr.rrblock.rrdata, addr.rrblock.datalen, name, len))
return 0;
addr.rr.u.block.datalen += len;
addr.rrblock.datalen += len;
}
else
{
/* desc is length of a block of data to be used as-is */
if (desc > endrr - p1)
desc = endrr - p1;
if (!blockdata_expand(addr.rr.u.block.rrdata, addr.rr.u.block.datalen, (char *)p1, desc))
if (!blockdata_expand(addr.rrblock.rrdata, addr.rrblock.datalen, (char *)p1, desc))
return 0;
addr.rr.u.block.datalen += desc;
addr.rrblock.datalen += desc;
p1 += desc;
}
} while (desc != -1);
@@ -968,7 +968,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
ttl = cttl;
if (flags & F_RR)
addr.rr.rrtype = qtype;
addr.rrdata.rrtype = qtype;
newc = cache_insert(name, &addr, C_IN, now, ttl, F_FORWARD | F_NEG | flags | (secure ? F_DNSSECOK : 0));
if (newc && cpp)
@@ -2103,8 +2103,14 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
do
{
int flags = crecp->flags;
unsigned short rrtype;
if (flags & F_KEYTAG)
rrtype = crecp->addr.rrblock.rrtype;
else
rrtype = crecp->addr.rrdata.rrtype;
if ((flags & F_NXDOMAIN) || crecp->addr.rr.rrtype == qtype)
if ((flags & F_NXDOMAIN) || rrtype == qtype)
{
if (crec_isstale(crecp, now))
{
@@ -2127,23 +2133,28 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
if (!dryrun)
{
char *rrdata = crecp->addr.rr.u.data;
unsigned short rrlen = crecp->addr.rr.len;
char *rrdata = NULL;
unsigned short rrlen = 0;
if (!(flags & F_NEG))
{
if (crecp->addr.rr.len == -1)
if (flags & F_KEYTAG)
{
rrlen = crecp->addr.rr.u.block.datalen;
rrdata = blockdata_retrieve(crecp->addr.rr.u.block.rrdata, crecp->addr.rr.u.block.datalen, NULL);
rrlen = crecp->addr.rrblock.datalen;
rrdata = blockdata_retrieve(crecp->addr.rrblock.rrdata, crecp->addr.rrblock.datalen, NULL);
}
else
{
rrlen = crecp->addr.rrdata.datalen;
rrdata = crecp->addr.rrdata.data;
}
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), NULL, qtype, C_IN, "t",
rrlen, rrdata))
anscount++;
}
if (!(flags & F_NEG) && add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), NULL, qtype, C_IN, "t",
rrlen, rrdata))
anscount++;
/* log after cache insertion as log_txt mangles rrdata */
if (qtype == T_TXT && !(crecp->flags & F_NEG))
log_txt(name, (unsigned char *)rrdata, rrlen, crecp->flags & F_DNSSECOK);