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gerrit.nordix.org / thekelleys / dnsmasq / dfb1f7ccf19d07155adebc0fbd8308719fe91e69 / . / src / rfc1035.c
blob: 5a961b8012146c6dbf18d197a9fa571a64ba9445 [file] [log] [blame]
/* dnsmasq is Copyright (c) 2000-2021 Simon Kelley
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 dated June, 1991, or
(at your option) version 3 dated 29 June, 2007.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "dnsmasq.h"
int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
char *name, int isExtract, int extrabytes)
{
unsigned char *cp = (unsigned char *)name, *p = *pp, *p1 = NULL;
unsigned int j, l, namelen = 0, hops = 0;
int retvalue = 1;
if (isExtract)
*cp = 0;
while (1)
{
unsigned int label_type;
if (!CHECK_LEN(header, p, plen, 1))
return 0;
if ((l = *p++) == 0)
/* end marker */
{
/* check that there are the correct no. of bytes after the name */
if (!CHECK_LEN(header, p1 ? p1 : p, plen, extrabytes))
return 0;
if (isExtract)
{
if (cp != (unsigned char *)name)
cp--;
*cp = 0; /* terminate: lose final period */
}
else if (*cp != 0)
retvalue = 2;
if (p1) /* we jumped via compression */
*pp = p1;
else
*pp = p;
return retvalue;
}
label_type = l & 0xc0;
if (label_type == 0xc0) /* pointer */
{
if (!CHECK_LEN(header, p, plen, 1))
return 0;
/* get offset */
l = (l&0x3f) << 8;
l |= *p++;
if (!p1) /* first jump, save location to go back to */
p1 = p;
hops++; /* break malicious infinite loops */
if (hops > 255)
return 0;
p = l + (unsigned char *)header;
}
else if (label_type == 0x00)
{ /* label_type = 0 -> label. */
namelen += l + 1; /* include period */
if (namelen >= MAXDNAME)
return 0;
if (!CHECK_LEN(header, p, plen, l))
return 0;
for(j=0; j<l; j++, p++)
if (isExtract)
{
unsigned char c = *p;
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID))
{
if (c == 0 || c == '.' || c == NAME_ESCAPE)
{
*cp++ = NAME_ESCAPE;
*cp++ = c+1;
}
else
*cp++ = c;
}
else
#endif
if (c != 0 && c != '.')
*cp++ = c;
else
return 0;
}
else
{
unsigned char c1 = *cp, c2 = *p;
if (c1 == 0)
retvalue = 2;
else
{
cp++;
if (c1 >= 'A' && c1 <= 'Z')
c1 += 'a' - 'A';
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID) && c1 == NAME_ESCAPE)
c1 = (*cp++)-1;
#endif
if (c2 >= 'A' && c2 <= 'Z')
c2 += 'a' - 'A';
if (c1 != c2)
retvalue = 2;
}
}
if (isExtract)
*cp++ = '.';
else if (*cp != 0 && *cp++ != '.')
retvalue = 2;
}
else
return 0; /* label types 0x40 and 0x80 not supported */
}
}
/* Max size of input string (for IPv6) is 75 chars.) */
#define MAXARPANAME 75
int in_arpa_name_2_addr(char *namein, union all_addr *addrp)
{
int j;
char name[MAXARPANAME+1], *cp1;
unsigned char *addr = (unsigned char *)addrp;
char *lastchunk = NULL, *penchunk = NULL;
if (strlen(namein) > MAXARPANAME)
return 0;
memset(addrp, 0, sizeof(union all_addr));
/* turn name into a series of asciiz strings */
/* j counts no. of labels */
for(j = 1,cp1 = name; *namein; cp1++, namein++)
if (*namein == '.')
{
penchunk = lastchunk;
lastchunk = cp1 + 1;
*cp1 = 0;
j++;
}
else
*cp1 = *namein;
*cp1 = 0;
if (j<3)
return 0;
if (hostname_isequal(lastchunk, "arpa") && hostname_isequal(penchunk, "in-addr"))
{
/* IP v4 */
/* address arrives as a name of the form
www.xxx.yyy.zzz.in-addr.arpa
some of the low order address octets might be missing
and should be set to zero. */
for (cp1 = name; cp1 != penchunk; cp1 += strlen(cp1)+1)
{
/* check for digits only (weeds out things like
50.0/24.67.28.64.in-addr.arpa which are used
as CNAME targets according to RFC 2317 */
char *cp;
for (cp = cp1; *cp; cp++)
if (!isdigit((unsigned char)*cp))
return 0;
addr[3] = addr[2];
addr[2] = addr[1];
addr[1] = addr[0];
addr[0] = atoi(cp1);
}
return F_IPV4;
}
else if (hostname_isequal(penchunk, "ip6") &&
(hostname_isequal(lastchunk, "int") || hostname_isequal(lastchunk, "arpa")))
{
/* IP v6:
Address arrives as 0.1.2.3.4.5.6.7.8.9.a.b.c.d.e.f.ip6.[int|arpa]
or \[xfedcba9876543210fedcba9876543210/128].ip6.[int|arpa]
Note that most of these the various representations are obsolete and
left-over from the many DNS-for-IPv6 wars. We support all the formats
that we can since there is no reason not to.
*/
if (*name == '\\' && *(name+1) == '[' &&
(*(name+2) == 'x' || *(name+2) == 'X'))
{
for (j = 0, cp1 = name+3; *cp1 && isxdigit((unsigned char) *cp1) && j < 32; cp1++, j++)
{
char xdig[2];
xdig[0] = *cp1;
xdig[1] = 0;
if (j%2)
addr[j/2] |= strtol(xdig, NULL, 16);
else
addr[j/2] = strtol(xdig, NULL, 16) << 4;
}
if (*cp1 == '/' && j == 32)
return F_IPV6;
}
else
{
for (cp1 = name; cp1 != penchunk; cp1 += strlen(cp1)+1)
{
if (*(cp1+1) || !isxdigit((unsigned char)*cp1))
return 0;
for (j = sizeof(struct in6_addr)-1; j>0; j--)
addr[j] = (addr[j] >> 4) | (addr[j-1] << 4);
addr[0] = (addr[0] >> 4) | (strtol(cp1, NULL, 16) << 4);
}
return F_IPV6;
}
}
return 0;
}
unsigned char *skip_name(unsigned char *ansp, struct dns_header *header, size_t plen, int extrabytes)
{
while(1)
{
unsigned int label_type;
if (!CHECK_LEN(header, ansp, plen, 1))
return NULL;
label_type = (*ansp) & 0xc0;
if (label_type == 0xc0)
{
/* pointer for compression. */
ansp += 2;
break;
}
else if (label_type == 0x80)
return NULL; /* reserved */
else if (label_type == 0x40)
{
/* Extended label type */
unsigned int count;
if (!CHECK_LEN(header, ansp, plen, 2))
return NULL;
if (((*ansp++) & 0x3f) != 1)
return NULL; /* we only understand bitstrings */
count = *(ansp++); /* Bits in bitstring */
if (count == 0) /* count == 0 means 256 bits */
ansp += 32;
else
ansp += ((count-1)>>3)+1;
}
else
{ /* label type == 0 Bottom six bits is length */
unsigned int len = (*ansp++) & 0x3f;
if (!ADD_RDLEN(header, ansp, plen, len))
return NULL;
if (len == 0)
break; /* zero length label marks the end. */
}
}
if (!CHECK_LEN(header, ansp, plen, extrabytes))
return NULL;
return ansp;
}
unsigned char *skip_questions(struct dns_header *header, size_t plen)
{
int q;
unsigned char *ansp = (unsigned char *)(header+1);
for (q = ntohs(header->qdcount); q != 0; q--)
{
if (!(ansp = skip_name(ansp, header, plen, 4)))
return NULL;
ansp += 4; /* class and type */
}
return ansp;
}
unsigned char *skip_section(unsigned char *ansp, int count, struct dns_header *header, size_t plen)
{
int i, rdlen;
for (i = 0; i < count; i++)
{
if (!(ansp = skip_name(ansp, header, plen, 10)))
return NULL;
ansp += 8; /* type, class, TTL */
GETSHORT(rdlen, ansp);
if (!ADD_RDLEN(header, ansp, plen, rdlen))
return NULL;
}
return ansp;
}
size_t resize_packet(struct dns_header *header, size_t plen, unsigned char *pheader, size_t hlen)
{
unsigned char *ansp = skip_questions(header, plen);
/* if packet is malformed, just return as-is. */
if (!ansp)
return plen;
if (!(ansp = skip_section(ansp, ntohs(header->ancount) + ntohs(header->nscount) + ntohs(header->arcount),
header, plen)))
return plen;
/* restore pseudoheader */
if (pheader && ntohs(header->arcount) == 0)
{
/* must use memmove, may overlap */
memmove(ansp, pheader, hlen);
header->arcount = htons(1);
ansp += hlen;
}
return ansp - (unsigned char *)header;
}
/* is addr in the non-globally-routed IP space? */
int private_net(struct in_addr addr, int ban_localhost)
{
in_addr_t ip_addr = ntohl(addr.s_addr);
return
(((ip_addr & 0xFF000000) == 0x7F000000) && ban_localhost) /* 127.0.0.0/8 (loopback) */ ||
((ip_addr & 0xFF000000) == 0x00000000) /* RFC 5735 section 3. "here" network */ ||
((ip_addr & 0xFF000000) == 0x0A000000) /* 10.0.0.0/8 (private) */ ||
((ip_addr & 0xFFF00000) == 0xAC100000) /* 172.16.0.0/12 (private) */ ||
((ip_addr & 0xFFFF0000) == 0xC0A80000) /* 192.168.0.0/16 (private) */ ||
((ip_addr & 0xFFFF0000) == 0xA9FE0000) /* 169.254.0.0/16 (zeroconf) */ ||
((ip_addr & 0xFFFFFF00) == 0xC0000200) /* 192.0.2.0/24 (test-net) */ ||
((ip_addr & 0xFFFFFF00) == 0xC6336400) /* 198.51.100.0/24(test-net) */ ||
((ip_addr & 0xFFFFFF00) == 0xCB007100) /* 203.0.113.0/24 (test-net) */ ||
((ip_addr & 0xFFFFFFFF) == 0xFFFFFFFF) /* 255.255.255.255/32 (broadcast)*/ ;
}
static int private_net6(struct in6_addr *a)
{
return
IN6_IS_ADDR_UNSPECIFIED(a) || /* RFC 6303 4.3 */
IN6_IS_ADDR_LOOPBACK(a) || /* RFC 6303 4.3 */
IN6_IS_ADDR_LINKLOCAL(a) || /* RFC 6303 4.5 */
((unsigned char *)a)[0] == 0xfd || /* RFC 6303 4.4 */
((u32 *)a)[0] == htonl(0x20010db8); /* RFC 6303 4.6 */
}
static unsigned char *do_doctor(unsigned char *p, int count, struct dns_header *header, size_t qlen, char *name, int *doctored)
{
int i, qtype, qclass, rdlen;
for (i = count; i != 0; i--)
{
if (name && option_bool(OPT_LOG))
{
if (!extract_name(header, qlen, &p, name, 1, 10))
return 0;
}
else if (!(p = skip_name(p, header, qlen, 10)))
return 0; /* bad packet */
GETSHORT(qtype, p);
GETSHORT(qclass, p);
p += 4; /* ttl */
GETSHORT(rdlen, p);
if (qclass == C_IN && qtype == T_A)
{
struct doctor *doctor;
struct in_addr addr;
if (!CHECK_LEN(header, p, qlen, INADDRSZ))
return 0;
/* alignment */
memcpy(&addr, p, INADDRSZ);
for (doctor = daemon->doctors; doctor; doctor = doctor->next)
{
if (doctor->end.s_addr == 0)
{
if (!is_same_net(doctor->in, addr, doctor->mask))
continue;
}
else if (ntohl(doctor->in.s_addr) > ntohl(addr.s_addr) ||
ntohl(doctor->end.s_addr) < ntohl(addr.s_addr))
continue;
addr.s_addr &= ~doctor->mask.s_addr;
addr.s_addr |= (doctor->out.s_addr & doctor->mask.s_addr);
/* Since we munged the data, the server it came from is no longer authoritative */
header->hb3 &= ~HB3_AA;
*doctored = 1;
memcpy(p, &addr, INADDRSZ);
break;
}
}
else if (qtype == T_TXT && name && option_bool(OPT_LOG))
{
unsigned char *p1 = p;
if (!CHECK_LEN(header, p1, qlen, rdlen))
return 0;
while ((p1 - p) < rdlen)
{
unsigned int i, len = *p1;
unsigned char *p2 = p1;
if ((p1 + len - p) >= rdlen)
return 0; /* bad packet */
/* make counted string zero-term and sanitise */
for (i = 0; i < len; i++)
{
if (!isprint((int)*(p2+1)))
break;
*p2 = *(p2+1);
p2++;
}
*p2 = 0;
my_syslog(LOG_INFO, "reply %s is %s", name, p1);
/* restore */
memmove(p1 + 1, p1, i);
*p1 = len;
p1 += len+1;
}
}
if (!ADD_RDLEN(header, p, qlen, rdlen))
return 0; /* bad packet */
}
return p;
}
static int find_soa(struct dns_header *header, size_t qlen, char *name, int *doctored)
{
unsigned char *p;
int qtype, qclass, rdlen;
unsigned long ttl, minttl = ULONG_MAX;
int i, found_soa = 0;
/* first move to NS section and find TTL from any SOA section */
if (!(p = skip_questions(header, qlen)) ||
!(p = do_doctor(p, ntohs(header->ancount), header, qlen, name, doctored)))
return 0; /* bad packet */
for (i = ntohs(header->nscount); i != 0; i--)
{
if (!(p = skip_name(p, header, qlen, 10)))
return 0; /* bad packet */
GETSHORT(qtype, p);
GETSHORT(qclass, p);
GETLONG(ttl, p);
GETSHORT(rdlen, p);
if ((qclass == C_IN) && (qtype == T_SOA))
{
found_soa = 1;
if (ttl < minttl)
minttl = ttl;
/* MNAME */
if (!(p = skip_name(p, header, qlen, 0)))
return 0;
/* RNAME */
if (!(p = skip_name(p, header, qlen, 20)))
return 0;
p += 16; /* SERIAL REFRESH RETRY EXPIRE */
GETLONG(ttl, p); /* minTTL */
if (ttl < minttl)
minttl = ttl;
}
else if (!ADD_RDLEN(header, p, qlen, rdlen))
return 0; /* bad packet */
}
/* rewrite addresses in additional section too */
if (!do_doctor(p, ntohs(header->arcount), header, qlen, NULL, doctored))
return 0;
if (!found_soa)
minttl = daemon->neg_ttl;
return minttl;
}
/* Note that the following code can create CNAME chains that don't point to a real record,
either because of lack of memory, or lack of SOA records. These are treated by the cache code as
expired and cleaned out that way.
Return 1 if we reject an address because it look like part of dns-rebinding attack. */
int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t now,
char **ipsets, int is_sign, int check_rebind, int no_cache_dnssec,
int secure, int *doctored)
{
unsigned char *p, *p1, *endrr, *namep;
int i, j, qtype, qclass, aqtype, aqclass, ardlen, res, searched_soa = 0;
unsigned long ttl = 0;
union all_addr addr;
#ifdef HAVE_IPSET
char **ipsets_cur;
#else
(void)ipsets; /* unused */
#endif
cache_start_insert();
/* find_soa is needed for dns_doctor and logging side-effects, so don't call it lazily if there are any. */
if (daemon->doctors || option_bool(OPT_LOG) || option_bool(OPT_DNSSEC_VALID))
{
searched_soa = 1;
ttl = find_soa(header, qlen, name, doctored);
if (*doctored)
{
if (secure)
return 0;
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID))
for (i = 0; i < ntohs(header->ancount); i++)
if (daemon->rr_status[i] != 0)
return 0;
#endif
}
}
/* go through the questions. */
p = (unsigned char *)(header+1);
for (i = ntohs(header->qdcount); i != 0; i--)
{
int found = 0, cname_count = CNAME_CHAIN;
struct crec *cpp = NULL;
int flags = RCODE(header) == NXDOMAIN ? F_NXDOMAIN : 0;
#ifdef HAVE_DNSSEC
int cname_short = 0;
#endif
unsigned long cttl = ULONG_MAX, attl;
namep = p;
if (!extract_name(header, qlen, &p, name, 1, 4))
return 0; /* bad packet */
GETSHORT(qtype, p);
GETSHORT(qclass, p);
if (qclass != C_IN)
continue;
/* PTRs: we chase CNAMEs here, since we have no way to
represent them in the cache. */
if (qtype == T_PTR)
{
int name_encoding = in_arpa_name_2_addr(name, &addr);
if (!name_encoding)
continue;
if (!(flags & F_NXDOMAIN))
{
cname_loop:
if (!(p1 = skip_questions(header, qlen)))
return 0;
for (j = 0; j < ntohs(header->ancount); j++)
{
int secflag = 0;
unsigned char *tmp = namep;
/* the loop body overwrites the original name, so get it back here. */
if (!extract_name(header, qlen, &tmp, name, 1, 0) ||
!(res = extract_name(header, qlen, &p1, name, 0, 10)))
return 0; /* bad packet */
GETSHORT(aqtype, p1);
GETSHORT(aqclass, p1);
GETLONG(attl, p1);
if ((daemon->max_ttl != 0) && (attl > daemon->max_ttl) && !is_sign)
{
(p1) -= 4;
PUTLONG(daemon->max_ttl, p1);
}
GETSHORT(ardlen, p1);
endrr = p1+ardlen;
/* TTL of record is minimum of CNAMES and PTR */
if (attl < cttl)
cttl = attl;
if (aqclass == C_IN && res != 2 && (aqtype == T_CNAME || aqtype == T_PTR))
{
if (!extract_name(header, qlen, &p1, name, 1, 0))
return 0;
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID) && daemon->rr_status[j] != 0)
{
/* validated RR anywhere in CNAME chain, don't cache. */
if (cname_short || aqtype == T_CNAME)
return 0;
secflag = F_DNSSECOK;
/* limit TTL based on signature. */
if (daemon->rr_status[j] < cttl)
cttl = daemon->rr_status[j];
}
#endif
if (aqtype == T_CNAME)
{
if (!cname_count--)
return 0; /* looped CNAMES, we can't cache. */
#ifdef HAVE_DNSSEC
cname_short = 1;
#endif
goto cname_loop;
}
cache_insert(name, &addr, C_IN, now, cttl, name_encoding | secflag | F_REVERSE);
found = 1;
}
p1 = endrr;
if (!CHECK_LEN(header, p1, qlen, 0))
return 0; /* bad packet */
}
}
if (!found && !option_bool(OPT_NO_NEG))
{
if (!searched_soa)
{
searched_soa = 1;
ttl = find_soa(header, qlen, NULL, doctored);
}
if (ttl)
cache_insert(NULL, &addr, C_IN, now, ttl, name_encoding | F_REVERSE | F_NEG | flags | (secure ? F_DNSSECOK : 0));
}
}
else
{
/* everything other than PTR */
struct crec *newc;
int addrlen = 0;
if (qtype == T_A)
{
addrlen = INADDRSZ;
flags |= F_IPV4;
}
else if (qtype == T_AAAA)
{
addrlen = IN6ADDRSZ;
flags |= F_IPV6;
}
else if (qtype == T_SRV)
flags |= F_SRV;
else
continue;
cname_loop1:
if (!(p1 = skip_questions(header, qlen)))
return 0;
for (j = 0; j < ntohs(header->ancount); j++)
{
int secflag = 0;
if (!(res = extract_name(header, qlen, &p1, name, 0, 10)))
return 0; /* bad packet */
GETSHORT(aqtype, p1);
GETSHORT(aqclass, p1);
GETLONG(attl, p1);
if ((daemon->max_ttl != 0) && (attl > daemon->max_ttl) && !is_sign)
{
(p1) -= 4;
PUTLONG(daemon->max_ttl, p1);
}
GETSHORT(ardlen, p1);
endrr = p1+ardlen;
if (aqclass == C_IN && res != 2 && (aqtype == T_CNAME || aqtype == qtype))
{
#ifdef HAVE_DNSSEC
if (option_bool(OPT_DNSSEC_VALID) && daemon->rr_status[j] != 0)
{
secflag = F_DNSSECOK;
/* limit TTl based on sig. */
if (daemon->rr_status[j] < attl)
attl = daemon->rr_status[j];
}
#endif
if (aqtype == T_CNAME)
{
if (!cname_count--)
return 0; /* looped CNAMES */
if ((newc = cache_insert(name, NULL, C_IN, now, attl, F_CNAME | F_FORWARD | secflag)))
{
newc->addr.cname.target.cache = NULL;
newc->addr.cname.is_name_ptr = 0;
if (cpp)
{
next_uid(newc);
cpp->addr.cname.target.cache = newc;
cpp->addr.cname.uid = newc->uid;
}
}
cpp = newc;
if (attl < cttl)
cttl = attl;
namep = p1;
if (!extract_name(header, qlen, &p1, name, 1, 0))
return 0;
goto cname_loop1;
}
else if (!(flags & F_NXDOMAIN))
{
found = 1;
if (flags & F_SRV)
{
unsigned char *tmp = namep;
if (!CHECK_LEN(header, p1, qlen, 6))
return 0; /* bad packet */
GETSHORT(addr.srv.priority, p1);
GETSHORT(addr.srv.weight, p1);
GETSHORT(addr.srv.srvport, p1);
if (!extract_name(header, qlen, &p1, name, 1, 0))
return 0;
addr.srv.targetlen = strlen(name) + 1; /* include terminating zero */
if (!(addr.srv.target = blockdata_alloc(name, addr.srv.targetlen)))
return 0;
/* we overwrote the original name, so get it back here. */
if (!extract_name(header, qlen, &tmp, name, 1, 0))
return 0;
}
else
{
/* copy address into aligned storage */
if (!CHECK_LEN(header, p1, qlen, addrlen))
return 0; /* bad packet */
memcpy(&addr, p1, addrlen);
/* check for returned address in private space */
if (check_rebind)
{
if ((flags & F_IPV4) &&
private_net(addr.addr4, !option_bool(OPT_LOCAL_REBIND)))
return 1;
/* Block IPv4-mapped IPv6 addresses in private IPv4 address space */
if (flags & F_IPV6)
{
if (IN6_IS_ADDR_V4MAPPED(&addr.addr6))
{
struct in_addr v4;
v4.s_addr = ((const uint32_t *) (&addr.addr6))[3];
if (private_net(v4, !option_bool(OPT_LOCAL_REBIND)))
return 1;
}
/* Check for link-local (LL) and site-local (ULA) IPv6 addresses */
if (IN6_IS_ADDR_LINKLOCAL(&addr.addr6) ||
IN6_IS_ADDR_SITELOCAL(&addr.addr6))
return 1;
/* Check for the IPv6 loopback address (::1) when
option rebind-localhost-ok is NOT set */
if (!option_bool(OPT_LOCAL_REBIND) &&
IN6_IS_ADDR_LOOPBACK(&addr.addr6))
return 1;
}
}
#ifdef HAVE_IPSET
if (ipsets && (flags & (F_IPV4 | F_IPV6)))
{
ipsets_cur = ipsets;
while (*ipsets_cur)
{
log_query((flags & (F_IPV4 | F_IPV6)) | F_IPSET, name, &addr, *ipsets_cur);
add_to_ipset(*ipsets_cur++, &addr, flags, 0);
}
}
#endif
}
newc = cache_insert(name, &addr, C_IN, now, attl, flags | F_FORWARD | secflag);
if (newc && cpp)
{
next_uid(newc);
cpp->addr.cname.target.cache = newc;
cpp->addr.cname.uid = newc->uid;
}
cpp = NULL;
}
}
p1 = endrr;
if (!CHECK_LEN(header, p1, qlen, 0))
return 0; /* bad packet */
}
if (!found && !option_bool(OPT_NO_NEG))
{
if (!searched_soa)
{
searched_soa = 1;
ttl = find_soa(header, qlen, NULL, doctored);
}
/* If there's no SOA to get the TTL from, but there is a CNAME
pointing at this, inherit its TTL */
if (ttl || cpp)
{
newc = cache_insert(name, NULL, C_IN, now, ttl ? ttl : cttl, F_FORWARD | F_NEG | flags | (secure ? F_DNSSECOK : 0));
if (newc && cpp)
{
next_uid(newc);
cpp->addr.cname.target.cache = newc;
cpp->addr.cname.uid = newc->uid;
}
}
}
}
}
/* Don't put stuff from a truncated packet into the cache.
Don't cache replies from non-recursive nameservers, since we may get a
reply containing a CNAME but not its target, even though the target
does exist. */
if (!(header->hb3 & HB3_TC) &&
!(header->hb4 & HB4_CD) &&
(header->hb4 & HB4_RA) &&
!no_cache_dnssec)
cache_end_insert();
return 0;
}
/* If the packet holds exactly one query
return F_IPV4 or F_IPV6 and leave the name from the query in name */
unsigned int extract_request(struct dns_header *header, size_t qlen, char *name, unsigned short *typep)
{
unsigned char *p = (unsigned char *)(header+1);
int qtype, qclass;
if (typep)
*typep = 0;
if (ntohs(header->qdcount) != 1 || OPCODE(header) != QUERY)
return 0; /* must be exactly one query. */
if (!extract_name(header, qlen, &p, name, 1, 4))
return 0; /* bad packet */
GETSHORT(qtype, p);
GETSHORT(qclass, p);
if (typep)
*typep = qtype;
if (qclass == C_IN)
{
if (qtype == T_A)
return F_IPV4;
if (qtype == T_AAAA)
return F_IPV6;
if (qtype == T_ANY)
return F_IPV4 | F_IPV6;
}
/* F_DNSSECOK as agument to search_servers() inhibits forwarding
to servers for domains without a trust anchor. This make the
behaviour for DS and DNSKEY queries we forward the same
as for DS and DNSKEY queries we originate. */
if (qtype == T_DS || qtype == T_DNSKEY)
return F_DNSSECOK;
return F_QUERY;
}
size_t setup_reply(struct dns_header *header, size_t qlen,
union all_addr *addrp, unsigned int flags, unsigned long ttl)
{
unsigned char *p;
if (!(p = skip_questions(header, qlen)))
return 0;
/* clear authoritative and truncated flags, set QR flag */
header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC )) | HB3_QR;
/* clear AD flag, set RA flag */
header->hb4 = (header->hb4 & ~HB4_AD) | HB4_RA;
header->nscount = htons(0);
header->arcount = htons(0);
header->ancount = htons(0); /* no answers unless changed below */
if (flags == F_NOERR)
SET_RCODE(header, NOERROR); /* empty domain */
else if (flags == F_NXDOMAIN)
SET_RCODE(header, NXDOMAIN);
else if (flags == F_SERVFAIL)
{
union all_addr a;
a.log.rcode = SERVFAIL;
log_query(F_CONFIG | F_RCODE, "error", &a, NULL);
SET_RCODE(header, SERVFAIL);
}
else if (flags & ( F_IPV4 | F_IPV6))
{
if (flags & F_IPV4)
{ /* we know the address */
SET_RCODE(header, NOERROR);
header->ancount = htons(1);
header->hb3 |= HB3_AA;
add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_A, C_IN, "4", addrp);
}
if (flags & F_IPV6)
{
SET_RCODE(header, NOERROR);
header->ancount = htons(ntohs(header->ancount) + 1);
header->hb3 |= HB3_AA;
add_resource_record(header, NULL, NULL, sizeof(struct dns_header), &p, ttl, NULL, T_AAAA, C_IN, "6", addrp);
}
}
else /* nowhere to forward to */
{
union all_addr a;
a.log.rcode = REFUSED;
log_query(F_CONFIG | F_RCODE, "error", &a, NULL);
SET_RCODE(header, REFUSED);
}
return p - (unsigned char *)header;
}
/* check if name matches local names ie from /etc/hosts or DHCP or local mx names. */
int check_for_local_domain(char *name, time_t now)
{
struct mx_srv_record *mx;
struct txt_record *txt;
struct interface_name *intr;
struct ptr_record *ptr;
struct naptr *naptr;
for (naptr = daemon->naptr; naptr; naptr = naptr->next)
if (hostname_issubdomain(name, naptr->name))
return 1;
for (mx = daemon->mxnames; mx; mx = mx->next)
if (hostname_issubdomain(name, mx->name))
return 1;
for (txt = daemon->txt; txt; txt = txt->next)
if (hostname_issubdomain(name, txt->name))
return 1;
for (intr = daemon->int_names; intr; intr = intr->next)
if (hostname_issubdomain(name, intr->name))
return 1;
for (ptr = daemon->ptr; ptr; ptr = ptr->next)
if (hostname_issubdomain(name, ptr->name))
return 1;
if (cache_find_non_terminal(name, now))
return 1;
return 0;
}
static int check_bad_address(struct dns_header *header, size_t qlen, struct bogus_addr *baddr, char *name, unsigned long *ttlp)
{
unsigned char *p;
int i, qtype, qclass, rdlen;
unsigned long ttl;
struct bogus_addr *baddrp;
struct in_addr addr;
/* skip over questions */
if (!(p = skip_questions(header, qlen)))
return 0; /* bad packet */
for (i = ntohs(header->ancount); i != 0; i--)
{
if (name && !extract_name(header, qlen, &p, name, 1, 10))
return 0; /* bad packet */
if (!name && !(p = skip_name(p, header, qlen, 10)))
return 0;
GETSHORT(qtype, p);
GETSHORT(qclass, p);
GETLONG(ttl, p);
GETSHORT(rdlen, p);
if (ttlp)
*ttlp = ttl;
if (qclass == C_IN && qtype == T_A)
{
if (!CHECK_LEN(header, p, qlen, INADDRSZ))
return 0;
for (baddrp = baddr; baddrp; baddrp = baddrp->next)
{
memcpy(&addr, p, INADDRSZ);
if ((addr.s_addr & baddrp->mask.s_addr) == baddrp->addr.s_addr)
return 1;
}
}
if (!ADD_RDLEN(header, p, qlen, rdlen))
return 0;
}
return 0;
}
/* Is the packet a reply with the answer address equal to addr?
If so mung is into an NXDOMAIN reply and also put that information
in the cache. */
int check_for_bogus_wildcard(struct dns_header *header, size_t qlen, char *name, time_t now)
{
unsigned long ttl;
if (check_bad_address(header, qlen, daemon->bogus_addr, name, &ttl))
{
/* Found a bogus address. Insert that info here, since there no SOA record
to get the ttl from in the normal processing */
cache_start_insert();
cache_insert(name, NULL, C_IN, now, ttl, F_IPV4 | F_FORWARD | F_NEG | F_NXDOMAIN);
cache_end_insert();
return 1;
}
return 0;
}
int check_for_ignored_address(struct dns_header *header, size_t qlen)
{
return check_bad_address(header, qlen, daemon->ignore_addr, NULL, NULL);
}
int add_resource_record(struct dns_header *header, char *limit, int *truncp, int nameoffset, unsigned char **pp,
unsigned long ttl, int *offset, unsigned short type, unsigned short class, char *format, ...)
{
va_list ap;
unsigned char *sav, *p = *pp;
int j;
unsigned short usval;
long lval;
char *sval;
#define CHECK_LIMIT(size) \
if (limit && p + (size) > (unsigned char*)limit) goto truncated;
va_start(ap, format); /* make ap point to 1st unamed argument */
if (truncp && *truncp)
goto truncated;
if (nameoffset > 0)
{
CHECK_LIMIT(2);
PUTSHORT(nameoffset | 0xc000, p);
}
else
{
char *name = va_arg(ap, char *);
if (name && !(p = do_rfc1035_name(p, name, limit)))
goto truncated;
if (nameoffset < 0)
{
CHECK_LIMIT(2);
PUTSHORT(-nameoffset | 0xc000, p);
}
else
{
CHECK_LIMIT(1);
*p++ = 0;
}
}
/* type (2) + class (2) + ttl (4) + rdlen (2) */
CHECK_LIMIT(10);
PUTSHORT(type, p);
PUTSHORT(class, p);
PUTLONG(ttl, p); /* TTL */
sav = p; /* Save pointer to RDLength field */
PUTSHORT(0, p); /* Placeholder RDLength */
for (; *format; format++)
switch (*format)
{
case '6':
CHECK_LIMIT(IN6ADDRSZ);
sval = va_arg(ap, char *);
memcpy(p, sval, IN6ADDRSZ);
p += IN6ADDRSZ;
break;
case '4':
CHECK_LIMIT(INADDRSZ);
sval = va_arg(ap, char *);
memcpy(p, sval, INADDRSZ);
p += INADDRSZ;
break;
case 'b':
CHECK_LIMIT(1);
usval = va_arg(ap, int);
*p++ = usval;
break;
case 's':
CHECK_LIMIT(2);
usval = va_arg(ap, int);
PUTSHORT(usval, p);
break;
case 'l':
CHECK_LIMIT(4);
lval = va_arg(ap, long);
PUTLONG(lval, p);
break;
case 'd':
/* get domain-name answer arg and store it in RDATA field */
if (offset)
*offset = p - (unsigned char *)header;
if (!(p = do_rfc1035_name(p, va_arg(ap, char *), limit)))
goto truncated;
CHECK_LIMIT(1);
*p++ = 0;
break;
case 't':
usval = va_arg(ap, int);
CHECK_LIMIT(usval);
sval = va_arg(ap, char *);
if (usval != 0)
memcpy(p, sval, usval);
p += usval;
break;
case 'z':
sval = va_arg(ap, char *);
usval = sval ? strlen(sval) : 0;
if (usval > 255)
usval = 255;
CHECK_LIMIT(usval + 1);
*p++ = (unsigned char)usval;
memcpy(p, sval, usval);
p += usval;
break;
}
va_end(ap); /* clean up variable argument pointer */
/* Now, store real RDLength. sav already checked against limit. */
j = p - sav - 2;
PUTSHORT(j, sav);
*pp = p;
return 1;
truncated:
va_end(ap);
if (truncp)
*truncp = 1;
return 0;
#undef CHECK_LIMIT
}
static unsigned long crec_ttl(struct crec *crecp, time_t now)
{
/* Return 0 ttl for DHCP entries, which might change
before the lease expires, unless configured otherwise. */
if (crecp->flags & F_DHCP)
{
int conf_ttl = daemon->use_dhcp_ttl ? daemon->dhcp_ttl : daemon->local_ttl;
/* Apply ceiling of actual lease length to configured TTL. */
if (!(crecp->flags & F_IMMORTAL) && (crecp->ttd - now) < conf_ttl)
return crecp->ttd - now;
return conf_ttl;
}
/* Immortal entries other than DHCP are local, and hold TTL in TTD field. */
if (crecp->flags & F_IMMORTAL)
return crecp->ttd;
/* Return the Max TTL value if it is lower than the actual TTL */
if (daemon->max_ttl == 0 || ((unsigned)(crecp->ttd - now) < daemon->max_ttl))
return crecp->ttd - now;
else
return daemon->max_ttl;
}
static int cache_validated(const struct crec *crecp)
{
return (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK));
}
/* return zero if we can't answer from cache, or packet size if we can */
size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
struct in_addr local_addr, struct in_addr local_netmask,
time_t now, int ad_reqd, int do_bit, int have_pseudoheader)
{
char *name = daemon->namebuff;
unsigned char *p, *ansp;
unsigned int qtype, qclass;
union all_addr addr;
int nameoffset;
unsigned short flag;
int q, ans, anscount = 0, addncount = 0;
int dryrun = 0;
struct crec *crecp;
int nxdomain = 0, notimp = 0, auth = 1, trunc = 0, sec_data = 1;
struct mx_srv_record *rec;
size_t len;
int rd_bit = (header->hb3 & HB3_RD);
/* never answer queries with RD unset, to avoid cache snooping. */
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;
/* 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. */
if (ntohs(header->arcount) != 0)
dryrun = 1;
for (rec = daemon->mxnames; rec; rec = rec->next)
rec->offset = 0;
rerun:
/* determine end of question section (we put answers there) */
if (!(ansp = skip_questions(header, qlen)))
return 0; /* bad packet */
/* now process each question, answers go in RRs after the question */
p = (unsigned char *)(header+1);
for (q = ntohs(header->qdcount); q != 0; q--)
{
int count = 255; /* catch loops */
/* save pointer to name for copying into answers */
nameoffset = p - (unsigned char *)header;
/* now extract name as .-concatenated string into name */
if (!extract_name(header, qlen, &p, name, 1, 4))
return 0; /* bad packet */
GETSHORT(qtype, p);
GETSHORT(qclass, p);
ans = 0; /* have we answered this question */
while (--count != 0 && (crecp = cache_find_by_name(NULL, name, now, F_CNAME)))
{
char *cname_target = cache_get_cname_target(crecp);
/* If the client asked for DNSSEC don't use cached data. */
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
(rd_bit && (!do_bit || cache_validated(crecp))))
{
if (crecp->flags & F_CONFIG || qtype == T_CNAME)
ans = 1;
if (!(crecp->flags & F_DNSSECOK))
sec_data = 0;
if (!dryrun)
{
log_query(crecp->flags, name, NULL, record_source(crecp->uid));
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), &nameoffset,
T_CNAME, C_IN, "d", cname_target))
anscount++;
}
}
else
return 0; /* give up if any cached CNAME in chain can't be used for DNSSEC reasons. */
strcpy(name, cname_target);
}
if (qtype == T_TXT || qtype == T_ANY)
{
struct txt_record *t;
for(t = daemon->txt; t ; t = t->next)
{
if (t->class == qclass && hostname_isequal(name, t->name))
{
ans = 1, sec_data = 0;
if (!dryrun)
{
unsigned long ttl = daemon->local_ttl;
int ok = 1;
#ifndef NO_ID
/* Dynamically generate stat record */
if (t->stat != 0)
{
ttl = 0;
if (!cache_make_stat(t))
ok = 0;
}
#endif
if (ok)
{
log_query(F_CONFIG | F_RRNAME, name, NULL, "<TXT>");
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
ttl, NULL,
T_TXT, t->class, "t", t->len, t->txt))
anscount++;
}
}
}
}
}
if (qclass == C_CHAOS)
{
/* don't forward *.bind and *.server chaos queries - always reply with NOTIMP */
if (hostname_issubdomain("bind", name) || hostname_issubdomain("server", name))
{
if (!ans)
{
notimp = 1, auth = 0;
if (!dryrun)
{
addr.log.rcode = NOTIMP;
log_query(F_CONFIG | F_RCODE, name, &addr, NULL);
}
ans = 1, sec_data = 0;
}
}
}
if (qclass == C_IN)
{
struct txt_record *t;
for (t = daemon->rr; t; t = t->next)
if ((t->class == qtype || qtype == T_ANY) && hostname_isequal(name, t->name))
{
ans = 1;
sec_data = 0;
if (!dryrun)
{
log_query(F_CONFIG | F_RRNAME, name, NULL, querystr(NULL, t->class));
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL,
t->class, C_IN, "t", t->len, t->txt))
anscount++;
}
}
if (qtype == T_PTR || qtype == T_ANY)
{
/* see if it's w.z.y.z.in-addr.arpa format */
int is_arpa = in_arpa_name_2_addr(name, &addr);
struct ptr_record *ptr;
struct interface_name* intr = NULL;
for (ptr = daemon->ptr; ptr; ptr = ptr->next)
if (hostname_isequal(name, ptr->name))
break;
if (is_arpa == F_IPV4)
for (intr = daemon->int_names; intr; intr = intr->next)
{
struct addrlist *addrlist;
for (addrlist = intr->addr; addrlist; addrlist = addrlist->next)
if (!(addrlist->flags & ADDRLIST_IPV6) && addr.addr4.s_addr == addrlist->addr.addr4.s_addr)
break;
if (addrlist)
break;
else
while (intr->next && strcmp(intr->intr, intr->next->intr) == 0)
intr = intr->next;
}
else if (is_arpa == F_IPV6)
for (intr = daemon->int_names; intr; intr = intr->next)
{
struct addrlist *addrlist;
for (addrlist = intr->addr; addrlist; addrlist = addrlist->next)
if ((addrlist->flags & ADDRLIST_IPV6) && IN6_ARE_ADDR_EQUAL(&addr.addr6, &addrlist->addr.addr6))
break;
if (addrlist)
break;
else
while (intr->next && strcmp(intr->intr, intr->next->intr) == 0)
intr = intr->next;
}
if (intr)
{
sec_data = 0;
ans = 1;
if (!dryrun)
{
log_query(is_arpa | F_REVERSE | F_CONFIG, intr->name, &addr, NULL);
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL,
T_PTR, C_IN, "d", intr->name))
anscount++;
}
}
else if (ptr)
{
ans = 1;
sec_data = 0;
if (!dryrun)
{
log_query(F_CONFIG | F_RRNAME, name, NULL, "<PTR>");
for (ptr = daemon->ptr; ptr; ptr = ptr->next)
if (hostname_isequal(name, ptr->name) &&
add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL,
T_PTR, C_IN, "d", ptr->ptr))
anscount++;
}
}
else if ((crecp = cache_find_by_addr(NULL, &addr, now, is_arpa)))
{
/* 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)) ||
(rd_bit && (!do_bit || cache_validated(crecp)) ))
{
do
{
/* don't answer wildcard queries with data not from /etc/hosts or dhcp leases */
if (qtype == T_ANY && !(crecp->flags & (F_HOSTS | F_DHCP)))
continue;
if (!(crecp->flags & F_DNSSECOK))
sec_data = 0;
ans = 1;
if (crecp->flags & F_NEG)
{
auth = 0;
if (crecp->flags & F_NXDOMAIN)
nxdomain = 1;
if (!dryrun)
log_query(crecp->flags & ~F_FORWARD, name, &addr, NULL);
}
else
{
if (!(crecp->flags & (F_HOSTS | F_DHCP)))
auth = 0;
if (!dryrun)
{
log_query(crecp->flags & ~F_FORWARD, cache_get_name(crecp), &addr,
record_source(crecp->uid));
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), NULL,
T_PTR, C_IN, "d", cache_get_name(crecp)))
anscount++;
}
}
} while ((crecp = cache_find_by_addr(crecp, &addr, now, is_arpa)));
}
}
else if (is_rev_synth(is_arpa, &addr, name))
{
ans = 1;
sec_data = 0;
if (!dryrun)
{
log_query(F_CONFIG | F_REVERSE | is_arpa, name, &addr, NULL);
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL,
T_PTR, C_IN, "d", name))
anscount++;
}
}
else if (option_bool(OPT_BOGUSPRIV) && (
(is_arpa == F_IPV6 && private_net6(&addr.addr6)) ||
(is_arpa == F_IPV4 && private_net(addr.addr4, 1))))
{
struct server *serv;
unsigned int namelen = strlen(name);
char *nameend = name + namelen;
/* see if have rev-server set */
for (serv = daemon->servers; serv; serv = serv->next)
{
unsigned int domainlen;
char *matchstart;
if ((serv->flags & (SERV_HAS_DOMAIN | SERV_NO_ADDR)) != SERV_HAS_DOMAIN)
continue;
domainlen = strlen(serv->domain);
if (domainlen == 0 || domainlen > namelen)
continue;
matchstart = nameend - domainlen;
if (hostname_isequal(matchstart, serv->domain) &&
(namelen == domainlen || *(matchstart-1) == '.' ))
break;
}
/* if no configured server, not in cache, enabled and private IPV4 address, return NXDOMAIN */
if (!serv)
{
ans = 1;
sec_data = 0;
nxdomain = 1;
if (!dryrun)
log_query(F_CONFIG | F_REVERSE | is_arpa | F_NEG | F_NXDOMAIN,
name, &addr, NULL);
}
}
}
for (flag = F_IPV4; flag; flag = (flag == F_IPV4) ? F_IPV6 : 0)
{
unsigned short type = (flag == F_IPV6) ? T_AAAA : T_A;
struct interface_name *intr;
if (qtype != type && qtype != T_ANY)
continue;
/* interface name stuff */
for (intr = daemon->int_names; intr; intr = intr->next)
if (hostname_isequal(name, intr->name))
break;
if (intr)
{
struct addrlist *addrlist;
int gotit = 0, localise = 0;
enumerate_interfaces(0);
/* See if a putative address is on the network from which we received
the query, is so we'll filter other answers. */
if (local_addr.s_addr != 0 && option_bool(OPT_LOCALISE) && type == T_A)
for (intr = daemon->int_names; intr; intr = intr->next)
if (hostname_isequal(name, intr->name))
for (addrlist = intr->addr; addrlist; addrlist = addrlist->next)
if (!(addrlist->flags & ADDRLIST_IPV6) &&
is_same_net(addrlist->addr.addr4, local_addr, local_netmask))
{
localise = 1;
break;
}
for (intr = daemon->int_names; intr; intr = intr->next)
if (hostname_isequal(name, intr->name))
{
for (addrlist = intr->addr; addrlist; addrlist = addrlist->next)
if (((addrlist->flags & ADDRLIST_IPV6) ? T_AAAA : T_A) == type)
{
if (localise &&
!is_same_net(addrlist->addr.addr4, local_addr, local_netmask))
continue;
if (addrlist->flags & ADDRLIST_REVONLY)
continue;
ans = 1;
sec_data = 0;
if (!dryrun)
{
gotit = 1;
log_query(F_FORWARD | F_CONFIG | flag, name, &addrlist->addr, NULL);
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL, type, C_IN,
type == T_A ? "4" : "6", &addrlist->addr))
anscount++;
}
}
}
if (!dryrun && !gotit)
log_query(F_FORWARD | F_CONFIG | flag | F_NEG, name, NULL, NULL);
continue;
}
if ((crecp = cache_find_by_name(NULL, name, now, flag | (dryrun ? F_NO_RR : 0))))
{
int localise = 0;
/* See if a putative address is on the network from which we received
the query, is so we'll filter other answers. */
if (local_addr.s_addr != 0 && option_bool(OPT_LOCALISE) && flag == F_IPV4)
{
struct crec *save = crecp;
do {
if ((crecp->flags & F_HOSTS) &&
is_same_net(crecp->addr.addr4, local_addr, local_netmask))
{
localise = 1;
break;
}
} while ((crecp = cache_find_by_name(crecp, name, now, flag)));
crecp = save;
}
/* If the client asked for DNSSEC don't use cached data. */
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
(rd_bit && (!do_bit || cache_validated(crecp)) ))
do
{
/* don't answer wildcard queries with data not from /etc/hosts
or DHCP leases */
if (qtype == T_ANY && !(crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)))
break;
if (!(crecp->flags & F_DNSSECOK))
sec_data = 0;
if (crecp->flags & F_NEG)
{
ans = 1;
auth = 0;
if (crecp->flags & F_NXDOMAIN)
nxdomain = 1;
if (!dryrun)
log_query(crecp->flags, name, NULL, NULL);
}
else
{
/* If we are returning local answers depending on network,
filter here. */
if (localise &&
(crecp->flags & F_HOSTS) &&
!is_same_net(crecp->addr.addr4, local_addr, local_netmask))
continue;
if (!(crecp->flags & (F_HOSTS | F_DHCP)))
auth = 0;
ans = 1;
if (!dryrun)
{
log_query(crecp->flags & ~F_REVERSE, name, &crecp->addr,
record_source(crecp->uid));
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), NULL, type, C_IN,
type == T_A ? "4" : "6", &crecp->addr))
anscount++;
}
}
} while ((crecp = cache_find_by_name(crecp, name, now, flag)));
}
else if (is_name_synthetic(flag, name, &addr))
{
ans = 1, sec_data = 0;
if (!dryrun)
{
log_query(F_FORWARD | F_CONFIG | flag, name, &addr, NULL);
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
daemon->local_ttl, NULL, type, C_IN, type == T_A ? "4" : "6", &addr))
anscount++;
}
}
}
if (qtype == T_MX || qtype == T_ANY)
{
int found = 0;
for (rec = daemon->mxnames; rec; rec = rec->next)
if (!rec->issrv && hostname_isequal(name, rec->name))
{
ans = found = 1;
sec_data = 0;
if (!dryrun)
{
int offset;
log_query(F_CONFIG | F_RRNAME, name, NULL, "<MX>");
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl,
&offset, T_MX, C_IN, "sd", rec->weight, rec->target))
{
anscount++;
if (rec->target)
rec->offset = offset;
}
}
}
if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) &&
cache_find_by_name(NULL, name, now, F_HOSTS | F_DHCP | F_NO_RR))
{
ans = 1;
sec_data = 0;
if (!dryrun)
{
log_query(F_CONFIG | F_RRNAME, name, NULL, "<MX>");
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl, NULL,
T_MX, C_IN, "sd", 1,
option_bool(OPT_SELFMX) ? name : daemon->mxtarget))
anscount++;
}
}
}
if (qtype == T_SRV || qtype == T_ANY)
{
int found = 0;
struct mx_srv_record *move = NULL, **up = &daemon->mxnames;
for (rec = daemon->mxnames; rec; rec = rec->next)
if (rec->issrv && hostname_isequal(name, rec->name))
{
found = ans = 1;
sec_data = 0;
if (!dryrun)
{
int offset;
log_query(F_CONFIG | F_RRNAME, name, NULL, "<SRV>");
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl,
&offset, T_SRV, C_IN, "sssd",
rec->priority, rec->weight, rec->srvport, rec->target))
{
anscount++;
if (rec->target)
rec->offset = offset;
}
}
/* unlink first SRV record found */
if (!move)
{
move = rec;
*up = rec->next;
}
else
up = &rec->next;
}
else
up = &rec->next;
/* put first SRV record back at the end. */
if (move)
{
*up = move;
move->next = NULL;
}
if (!found)
{
if ((crecp = cache_find_by_name(NULL, name, now, F_SRV | (dryrun ? F_NO_RR : 0))) &&
rd_bit && (!do_bit || (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK))))
{
if (!(crecp->flags & F_DNSSECOK))
sec_data = 0;
auth = 0;
found = ans = 1;
do {
if (crecp->flags & F_NEG)
{
if (crecp->flags & F_NXDOMAIN)
nxdomain = 1;
if (!dryrun)
log_query(crecp->flags, name, NULL, NULL);
}
else if (!dryrun)
{
char *target = blockdata_retrieve(crecp->addr.srv.target, crecp->addr.srv.targetlen, NULL);
log_query(crecp->flags, name, NULL, 0);
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp,
crec_ttl(crecp, now), NULL, T_SRV, C_IN, "sssd",
crecp->addr.srv.priority, crecp->addr.srv.weight, crecp->addr.srv.srvport,
target))
anscount++;
}
} while ((crecp = cache_find_by_name(crecp, name, now, F_SRV)));
}
}
if (!found && option_bool(OPT_FILTER) && (qtype == T_SRV || (qtype == T_ANY && strchr(name, '_'))))
{
ans = 1;
sec_data = 0;
if (!dryrun)
log_query(F_CONFIG | F_NEG, name, NULL, NULL);
}
}
if (qtype == T_NAPTR || qtype == T_ANY)
{
struct naptr *na;
for (na = daemon->naptr; na; na = na->next)
if (hostname_isequal(name, na->name))
{
ans = 1;
sec_data = 0;
if (!dryrun)
{
log_query(F_CONFIG | F_RRNAME, name, NULL, "<NAPTR>");
if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, daemon->local_ttl,
NULL, T_NAPTR, C_IN, "sszzzd",
na->order, na->pref, na->flags, na->services, na->regexp, na->replace))
anscount++;
}
}
}
if (qtype == T_MAILB)
ans = 1, nxdomain = 1, sec_data = 0;
if (qtype == T_SOA && option_bool(OPT_FILTER))
{
ans = 1;
sec_data = 0;
if (!dryrun)
log_query(F_CONFIG | F_NEG, name, &addr, NULL);
}
}
if (!ans)
return 0; /* failed to answer a question */
}
if (dryrun)
{
dryrun = 0;
goto rerun;
}
/* create an additional data section, for stuff in SRV and MX record replies. */
for (rec = daemon->mxnames; rec; rec = rec->next)
if (rec->offset != 0)
{
/* squash dupes */
struct mx_srv_record *tmp;
for (tmp = rec->next; tmp; tmp = tmp->next)
if (tmp->offset != 0 && hostname_isequal(rec->target, tmp->target))
tmp->offset = 0;
crecp = NULL;
while ((crecp = cache_find_by_name(crecp, rec->target, now, F_IPV4 | F_IPV6)))
{
int type = crecp->flags & F_IPV4 ? T_A : T_AAAA;
if (crecp->flags & F_NEG)
continue;
if (add_resource_record(header, limit, NULL, rec->offset, &ansp,
crec_ttl(crecp, now), NULL, type, C_IN,
crecp->flags & F_IPV4 ? "4" : "6", &crecp->addr))
addncount++;
}
}
/* done all questions, set up header and return length of result */
/* clear authoritative and truncated flags, set QR flag */
header->hb3 = (header->hb3 & ~(HB3_AA | HB3_TC)) | HB3_QR;
/* set RA flag */
header->hb4 |= HB4_RA;
/* authoritative - only hosts and DHCP derived names. */
if (auth)
header->hb3 |= HB3_AA;
/* truncation */
if (trunc)
header->hb3 |= HB3_TC;
if (nxdomain)
SET_RCODE(header, NXDOMAIN);
else if (notimp)
SET_RCODE(header, NOTIMP);
else
SET_RCODE(header, NOERROR); /* no error */
header->ancount = htons(anscount);
header->nscount = htons(0);
header->arcount = htons(addncount);
len = ansp - (unsigned char *)header;
/* Advertise our packet size limit in our reply */
if (have_pseudoheader)
len = add_pseudoheader(header, len, (unsigned char *)limit, daemon->edns_pktsz, 0, NULL, 0, do_bit, 0);
if (ad_reqd && sec_data)
header->hb4 |= HB4_AD;
else
header->hb4 &= ~HB4_AD;
return len;
}