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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
Download Patch File Download Diff File Expand all files Collapse all files

42
src/cache.c
View File

@@ -275,8 +275,8 @@ static void cache_blockdata_free(struct crec *crecp)
{
if (!(crecp->flags & F_NEG))
{
if (crecp->flags & F_RR && crecp->addr.rr.len == -1)
blockdata_free(crecp->addr.rr.u.block.rrdata);
if ((crecp->flags & F_RR) && (crecp->flags & F_KEYTAG))
blockdata_free(crecp->addr.rrblock.rrdata);
#ifdef HAVE_DNSSEC
else if (crecp->flags & F_DNSKEY)
blockdata_free(crecp->addr.key.keydata);
@@ -469,10 +469,20 @@ static struct crec *cache_scan_free(char *name, union all_addr *addr, unsigned s
{
if ((crecp->flags & F_FORWARD) && hostname_isequal(cache_get_name(crecp), name))
{
int rrmatch = 0;
if (crecp->flags & flags & F_RR)
{
unsigned short rrc = (crecp->flags & F_KEYTAG) ? crecp->addr.rrblock.rrtype : crecp->addr.rrdata.rrtype;
unsigned short rra = (flags & F_KEYTAG) ? addr->rrblock.rrtype : addr->rrdata.rrtype;
if (rrc == rra)
rrmatch = 1;
}
/* Don't delete DNSSEC in favour of a CNAME, they can co-exist */
if ((flags & crecp->flags & (F_IPV4 | F_IPV6 | F_RR | F_NXDOMAIN)) ||
if ((flags & crecp->flags & (F_IPV4 | F_IPV6 | F_NXDOMAIN)) ||
(((crecp->flags | flags) & F_CNAME) && !(crecp->flags & (F_DNSKEY | F_DS))) ||
((crecp->flags & flags & F_RR) && addr->rr.rrtype == crecp->addr.rr.rrtype))
rrmatch)
{
if (crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG))
return crecp;
@@ -795,8 +805,8 @@ void cache_end_insert(void)
if (flags & F_RR)
{
/* A negative RR entry is possible and has no data, obviously. */
if (!(flags & F_NEG) && new_chain->addr.rr.len == -1)
blockdata_write(new_chain->addr.rr.u.block.rrdata, new_chain->addr.rr.u.block.datalen, daemon->pipe_to_parent);
if (!(flags & F_NEG) && (flags & F_KEYTAG))
blockdata_write(new_chain->addr.rrblock.rrdata, new_chain->addr.rrblock.datalen, daemon->pipe_to_parent);
}
#ifdef HAVE_DNSSEC
if (flags & F_DNSKEY)
@@ -869,8 +879,8 @@ int cache_recv_insert(time_t now, int fd)
if (!read_write(fd, (unsigned char *)&addr, sizeof(addr), 1))
return 0;
if ((flags & F_RR) && !(flags & F_NEG) &&
addr.rr.len == -1 && !(addr.rr.u.block.rrdata = blockdata_read(fd, addr.rr.u.block.datalen)))
if ((flags & F_RR) && !(flags & F_NEG) && (flags & F_KEYTAG)
&& !(addr.rrblock.rrdata = blockdata_read(fd, addr.rrblock.datalen)))
return 0;
#ifdef HAVE_DNSSEC
if (flags & F_DNSKEY)
@@ -1796,7 +1806,12 @@ static void dump_cache_entry(struct crec *cache, time_t now)
if ((cache->flags & F_CNAME) && !is_outdated_cname_pointer(cache))
a = sanitise(cache_get_cname_target(cache));
else if (cache->flags & F_RR)
sprintf(a, "%s", querystr(NULL, cache->addr.rr.rrtype));
{
if (cache->flags & F_KEYTAG)
sprintf(a, "%s", querystr(NULL, cache->addr.rrblock.rrtype));
else
sprintf(a, "%s", querystr(NULL, cache->addr.rrdata.rrtype));
}
#ifdef HAVE_DNSSEC
else if (cache->flags & F_DS)
{
@@ -2052,7 +2067,14 @@ void log_query(unsigned int flags, char *name, union all_addr *addr, char *arg,
{
dest = daemon->addrbuff;
if (flags & F_RR)
{
if (flags & F_KEYTAG)
dest = querystr(NULL, addr->rrblock.rrtype);
else
dest = querystr(NULL, addr->rrdata.rrtype);
}
else if (flags & F_KEYTAG)
sprintf(daemon->addrbuff, arg, addr->log.keytag, addr->log.algo, addr->log.digest);
else if (flags & F_RCODE)
{
@@ -2083,8 +2105,6 @@ void log_query(unsigned int flags, char *name, union all_addr *addr, char *arg,
sprintf(portstring, "#%u", type);
}
}
else if (flags & F_RR)
dest = querystr(NULL, addr->rr.rrtype);
else
dest = arg;
}

20
src/dnsmasq.h
View File

@@ -329,21 +329,23 @@ union all_addr {
unsigned short keytag, algo, digest, rcode;
int ede;
} log;
/* for arbitrary RR record. */
/* for arbitrary RR record stored in block */
struct {
#define RR_IMDATALEN 13 /* 16 - sizeof(short) - sizeof (char) */
unsigned short rrtype;
char len; /* -1 for blockdata */
union {
char data[RR_IMDATALEN];
struct {
unsigned short datalen;
struct blockdata *rrdata;
} block;
} u;
} rr;
} rrblock;
/* for arbitrary RR record small enough to go in addr.
NOTE: rrblock and rrdata are discriminated by the F_KEYTAG bit
in the cache flags. */
struct datablock {
unsigned short rrtype;
unsigned char datalen;
char data[];
} rrdata;
};
#define RR_IMDATALEN (sizeof(union all_addr) - offsetof(struct datablock, data))
struct bogus_addr {
int is6, prefix;

57
src/rfc1035.c
View File

@@ -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;
addr.rrdata.rrtype = aqtype;
addr.rrdata.datalen = (char)ardlen;
if (ardlen != 0)
memcpy(addr.rr.u.data, p1, ardlen);
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_NXDOMAIN) || crecp->addr.rr.rrtype == qtype)
if (flags & F_KEYTAG)
rrtype = crecp->addr.rrblock.rrtype;
else
rrtype = crecp->addr.rrdata.rrtype;
if ((flags & F_NXDOMAIN) || rrtype == qtype)
{
if (crec_isstale(crecp, now))
{
@@ -2127,22 +2133,27 @@ 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,
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))