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rbldnsd_packet.c
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rbldnsd_packet.c
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/* DNS packet handling routines for rbldnsd
*/
#include <string.h>
#include <time.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <syslog.h>
#include "rbldnsd.h"
#ifndef NO_IPv6
# ifndef NI_MAXHOST
# define IPSIZE 1025
# else
# define IPSIZE NI_MAXHOST
# endif
#else
# define IPSIZE 16
#endif
#define MAX_GLUE (MAX_NS*2)
static int addrr_soa(struct dnspacket *pkt, const struct zone *zone, int auth);
static int addrr_ns(struct dnspacket *pkt, const struct zone *zone, int auth);
static int version_req(struct dnspacket *pkt, const struct dnsquery *qry);
/* DNS packet:
* bytes comment */
/* 0:1 identifier (client supplied) */
#define p_id1 0
#define p_id2 1
/* 2 flags1 */
#define p_f1 2
#define pf1_qr 0x80 /* query response flag */
#define pf1_opcode 0x78 /* opcode, 0 = query */
#define pf1_aa 0x04 /* auth answer */
#define pf1_tc 0x02 /* truncation flag */
#define pf1_rd 0x01 /* recursion desired (may be set in query) */
/* 3 flags2 */
#define p_f2 3
#define pf2_ra 0x80 /* recursion available */
#define pf2_z 0x70 /* reserved */
#define pf2_rcode 0x0f /* response code */
/* 0 ok, 1 format error, 2 servfail, 3 nxdomain, 4 notimpl, 5 refused */
/* 4:5 qdcount (numqueries) */
#define p_qdcnt1 4
#define p_qdcnt2 5
/* 6:7 ancount (numanswers) */
#define p_ancnt1 6
#define p_ancnt2 7
/* 8:9 nscount (numauthority) */
#define p_nscnt1 8
#define p_nscnt2 9
/* 10:11 arcount (numadditional) */
#define p_arcnt1 10
#define p_arcnt2 11
#define p_hdrsize 12 /* size of packet header */
/* next is a DN name, a series of labels with first byte is label's length,
* terminated by zero-length label (i.e. at least one zero byte is here)
* next two bytes are query type (A, SOA etc)
* next two bytes are query class (IN, HESIOD etc)
*/
static int
parsequery(struct dnspacket *pkt, unsigned qlen,
struct dnsquery *qry) {
/* parsing incoming query. Untrusted data read directly from the network.
* pkt->p_buf is a buffer - data that was read (DNS_EDNS0_MAXPACKET max).
* qlen is number of bytes actually read (packet length)
* first p_hdrsize bytes is header, next is query DN,
* next are QTYPE and QCLASS (2x2 bytes).
* If NSCNT==0 && ARCNT==1, and an OPT record comes after the query,
* EDNS0 packet size gets extracted from the OPT record.
* Rest of data is ignored.
* Returns true on success, 0 on failure.
* Upon successeful return, pkt->p_sans = pkt->p_cur points to the end of
* the query section (where our answers will be placed), and
* pkt->p_endp is initialized to point to the real end of answers.
* Real end of answers is:
* for non-EDNS0-aware clients it's pkt->p_buf+DNS_MAXPACKET, and
* if a vaild EDNS0 UDPsize is given, it will be pkt->p_buf+UDPsize-11,
* with the 11 bytes needed for a minimal OPT record.
* In replypacket() we check whenever all our answers fits in standard
* UDP buffer size (DNS_MAXPACKET), and if not (which means we're replying
* to EDNS0-aware client due to the above rules), we just add proper OPT
* record at the end.
*/
register unsigned const char *q = pkt->p_buf;
register unsigned const char *x, *e;
register unsigned char *d;
unsigned qlab; /* number of labels in qDN */
x = q + qlen - 5; /* last possible qDN zero terminator position */
/* qlen isn't needed anymore, it'll be used as length of qDN below */
if (q + p_hdrsize > x) /* short packet (header isn't here) */
return 0;
else if (q + p_hdrsize + DNS_MAXDN <= x)
x = q + p_hdrsize + DNS_MAXDN - 1; /* constrain query DN to DNS_MAXDN */
if (q[p_f1] & pf1_qr) /* response packet?! */
return 0;
if (q[p_qdcnt1] || q[p_qdcnt2] != 1) /* qdcount should be == 1 */
return 0;
/* parse and lowercase query DN, count and init labels */
qlab = 0; /* number of labels so far */
q += p_hdrsize; /* start of qDN */
d = qry->q_dn; /* destination lowercased DN */
while((*d = *q) != 0) { /* loop by DN lables */
qry->q_lptr[qlab++] = d++; /* another label */
e = q + *q + 1; /* end of this label */
if (*q > DNS_MAXLABEL /* too long label? */
|| e > x) /* or it ends past packet? */
return 0;
/* lowercase it */
++q; /* length */
do *d++ = dns_dnlc(*q); /* lowercase each char */
while(++q < e); /* until end of label */
}
/* d points to qDN terminator now */
qry->q_dnlen = d - qry->q_dn + 1;
qry->q_dnlab = qlab;
/* q is end of qDN. decode qtype and qclass, and prepare for an answer */
++q;
qry->q_type = ((unsigned)(q[0]) << 8) | q[1];
qry->q_class = ((unsigned)(q[2]) << 8) | q[3];
q += 4;
pkt->p_sans = (unsigned char *)q; /* answers will start here */
pkt->p_cur = (unsigned char *)q; /* and current answer pointer is here */
d = pkt->p_buf;
if (q < x &&
d[p_nscnt1] == 0 && d[p_nscnt2] == 0 &&
d[p_arcnt1] == 0 && d[p_arcnt2] == 1 &&
q[0] == 0 /* empty DN */ &&
q[1] == (DNS_T_OPT>>8) && q[2] == (DNS_T_OPT&255)) {
qlen = (((unsigned)q[3]) << 8) | q[4];
/* 11 bytes are needed to encode minimal EDNS0 OPT record */
if (qlen < DNS_MAXPACKET + 11)
qlen = DNS_MAXPACKET;
else if (qlen > sizeof(pkt->p_buf) - 11)
qlen = sizeof(pkt->p_buf) - 11;
else
qlen -= 11;
pkt->p_endp = d + qlen;
}
else
pkt->p_endp = d + DNS_MAXPACKET;
return 1;
}
#define digit(c) ((c) >= '0' && (c) <= '9')
#define d2n(c) ((unsigned)((c) - '0'))
static int dntoip4addr(const unsigned char *q, ip4addr_t *ap) {
unsigned o, a = 0;
#define oct(q,o) \
switch(*q) { \
case 1: \
if (!digit(q[1])) \
return 0; \
o = d2n(q[1]); \
break; \
case 2: \
if (!digit(q[1]) || !digit(q[2])) \
return 0; \
o = d2n(q[1]) * 10 + d2n(q[2]); \
break; \
case 3: \
if (!digit(q[1]) || !digit(q[2]) || !digit(q[3])) \
return 0; \
o = d2n(q[1]) * 100 + d2n(q[2]) * 10 + d2n(q[3]); \
if (o > 255) return 0; \
break; \
default: return 0; \
}
oct(q,o); a |= o; q += *q + 1;
oct(q,o); a |= o << 8; q += *q + 1;
oct(q,o); a |= o << 16; q += *q + 1;
oct(q,o); a |= o << 24;
*ap = a;
return 1;
#undef oct
}
static int dntoip6addr(const unsigned char *q, ip6oct_t ap[IP6ADDR_FULL]) {
unsigned o1, o2, c;
for(c = IP6ADDR_FULL; c; ) {
if (*q++ != 1)
return 0;
if (digit(*q)) o2 = d2n(*q++);
else if (*q >= 'a' && *q <= 'f') o2 = *q++ - 'a' + 10;
else return 0;
if (*q++ != 1)
return 0;
if (digit(*q)) o1 = d2n(*q++);
else if (*q >= 'a' && *q <= 'f') o1 = *q++ - 'a' + 10;
else return 0;
ap[--c] = (o1 << 4) | o2;
}
return 1;
}
static const ip6oct_t ip6mapped_pfx[12] =
"\0\0\0\0\0\0\0\0"
"\0\0\377\377";
/* parse DN (as in 4.3.2.1.in-addr.arpa) to ip4addr_t (4 octets 0..255).
* parse DN (as in 0.1.2.3.4.5...f.base.dn) to ip6 address (32 nibbles 0..f)
*/
static void dntoip(struct dnsqinfo *qi, int flags) {
const unsigned char *q = qi->qi_dn;
unsigned qlab = qi->qi_dnlab;
qi->qi_ip4valid = qlab == 4 && dntoip4addr(q, &qi->qi_ip4);
if (qi->qi_ip4valid)
qi->qi_ip6valid = 0;
else {
qi->qi_ip6valid =
qlab == 32 && qi->qi_dnlen0 == 64 && dntoip6addr(q, qi->qi_ip6);
if (qi->qi_ip6valid && (flags & DSTF_IP4REV)) {
if (qi->qi_ip6[0] == 0x20 && qi->qi_ip6[1] == 0x02) {
/* construct IP4 from 2002:V4ADDR::/48 6to4 address, RFC3056 */
qi->qi_ip4 = unpack32(qi->qi_ip6 + 2);
qi->qi_ip4valid = 1;
}
else if (memcmp(qi->qi_ip6, ip6mapped_pfx, sizeof(ip6mapped_pfx)) == 0) {
/* construct IP4 from IP4MAPPED, ::ffff:V4ADDR */
qi->qi_ip4 = unpack32(qi->qi_ip6 + 12);
qi->qi_ip4valid = 1;
qi->qi_ip6valid = 0; /* don't bother looking v6 */
}
}
}
}
const struct zone *
findqzone(const struct zone *zone,
unsigned dnlen, unsigned dnlab, unsigned char *const *const dnlptr,
struct dnsqinfo *qi) {
const unsigned char *q;
for(;; zone = zone->z_next) {
if (!zone) return NULL;
if (zone->z_dnlab > dnlab) continue;
q = dnlptr[dnlab - zone->z_dnlab];
if (memcmp(zone->z_dn, q, zone->z_dnlen - 1)) continue;
break;
}
qi->qi_dn = dnlptr[0];
qi->qi_dnlptr = dnlptr;
qi->qi_dnlab = dnlab - zone->z_dnlab;
qi->qi_dnlen0 = dnlen - zone->z_dnlen;
if (zone->z_dstflags & (DSTF_IP4REV|DSTF_IP6REV)) /* IP address */
dntoip(qi, zone->z_dstflags);
return zone;
}
#ifdef NO_STATS
# define do_stats(x)
#else
# define do_stats(x) x
#endif
/* construct reply to a query. */
int replypacket(struct dnspacket *pkt, unsigned qlen, struct zone *zone, struct dnsqinfo *qi) {
struct dnsquery qry; /* query structure */
unsigned char *h = pkt->p_buf; /* packet's header */
const struct dslist *dsl;
int found;
extern int lazy; /*XXX hack*/
pkt->p_substrr = 0;
/* check global ACL */
if (g_dsacl && g_dsacl->ds_stamp) {
found = ds_acl_query(g_dsacl, pkt);
if (found & NSQUERY_IGNORE) {
do_stats(gstats.q_err += 1; gstats.b_in += qlen);
return 0;
}
}
else {
found = 0;
}
if (!parsequery(pkt, qlen, &qry)) {
do_stats(gstats.q_err += 1; gstats.b_in += qlen);
return 0;
}
/* from now on, we see (almost?) valid dns query, should reply */
#define setnonauth(h) (h[p_f1] &= ~pf1_aa)
#define _refuse(code,lab) \
do { setnonauth(h); h[p_f2] = (code); goto lab; } while(0)
#define refuse(code) _refuse(code, err_nz)
#define rlen() pkt->p_cur - h
/* construct reply packet */
/* identifier already in place */
/* flags will be set up later */
/* qdcount already set up in query */
/* all counts (qd,an,ns,ar) are <= 255 due to size limit */
h[p_ancnt1] = h[p_ancnt2] = 0;
h[p_nscnt1] = h[p_nscnt2] = 0;
h[p_arcnt1] = h[p_arcnt2] = 0;
if (h[p_f1] & (pf1_opcode | pf1_aa | pf1_tc | pf1_qr)) {
h[p_f1] = pf1_qr;
refuse(DNS_R_NOTIMPL);
}
h[p_f1] |= pf1_qr;
if (qry.q_class == DNS_C_IN)
h[p_f1] |= pf1_aa;
else if (qry.q_class != DNS_C_ANY) {
if (version_req(pkt, &qry)) {
do_stats(gstats.q_ok += 1; gstats.b_in += qlen; gstats.b_out += rlen());
return rlen();
}
else
refuse(DNS_R_REFUSED);
}
switch(qry.q_type) {
case DNS_T_ANY: qi->qi_tflag = NSQUERY_ANY; break;
case DNS_T_A: qi->qi_tflag = NSQUERY_A; break;
case DNS_T_TXT: qi->qi_tflag = NSQUERY_TXT; break;
case DNS_T_NS: qi->qi_tflag = NSQUERY_NS; break;
case DNS_T_SOA: qi->qi_tflag = NSQUERY_SOA; break;
case DNS_T_MX: qi->qi_tflag = NSQUERY_MX; break;
default:
if (qry.q_type >= DNS_T_TSIG)
refuse(DNS_R_NOTIMPL);
qi->qi_tflag = NSQUERY_OTHER;
}
qi->qi_tflag |= found;
h[p_f2] = DNS_R_NOERROR;
/* find matching zone */
zone = (struct zone*)
findqzone(zone, qry.q_dnlen, qry.q_dnlab, qry.q_lptr, qi);
if (!zone) /* not authoritative */
refuse(DNS_R_REFUSED);
/* check global ACL key, we can do it merely after zone data has been parsed */
if (g_dsaclkey && g_dsaclkey->ds_stamp) {
found = ds_aclkey_query(g_dsaclkey, qi, pkt);
if (found & NSQUERY_IGNORE) {
do_stats(gstats.q_dropped += 1; gstats.b_in += qlen);
return 0;
}
}
/* found matching zone */
#undef refuse
#define refuse(code) _refuse(code, err_z)
do_stats(zone->z_stats.b_in += qlen);
if (zone->z_dsacl && zone->z_dsacl->ds_stamp) {
qi->qi_tflag |= ds_acl_query(zone->z_dsacl, pkt);
if (qi->qi_tflag & NSQUERY_IGNORE) {
do_stats(gstats.q_err += 1);
return 0;
}
}
if (zone->z_dsaclkey && zone->z_dsaclkey->ds_stamp) {
qi->qi_tflag |= ds_aclkey_query(zone->z_dsaclkey, qi, pkt);
if (qi->qi_tflag & NSQUERY_IGNORE) {
do_stats(gstats.q_dropped += 1);
return 0;
}
}
if (!zone->z_stamp) /* do not answer if not loaded */
refuse(DNS_R_SERVFAIL);
if (qi->qi_tflag & NSQUERY_REFUSE)
refuse(DNS_R_REFUSED);
if ((found = call_hook(query_access, (pkt->p_peer, zone, qi)))) {
if (found < 0) return 0;
refuse(DNS_R_REFUSED);
}
if (qi->qi_dnlab == 0) { /* query to base zone: SOA and NS */
found = NSQUERY_FOUND;
/* NS and SOA with auth=0 will only touch answer section */
if ((qi->qi_tflag & NSQUERY_SOA) && !addrr_soa(pkt, zone, 0))
found = 0;
else
if ((qi->qi_tflag & NSQUERY_NS) && !addrr_ns(pkt, zone, 0))
found = 0;
if (!found) {
pkt->p_cur = pkt->p_sans;
h[p_ancnt2] = h[p_nscnt2] = 0;
refuse(DNS_R_REFUSED);
}
}
else /* not to zone base DN */
found = 0;
/* search the datasets */
for(dsl = zone->z_dsl; dsl; dsl = dsl->dsl_next)
found |= dsl->dsl_queryfn(dsl->dsl_ds, qi, pkt);
if (found & NSQUERY_ADDPEER) {
#ifdef NO_IPv6
addrr_a_txt(pkt, qi->qi_tflag, pkt->p_substrr,
inet_ntoa(((struct sockaddr_in*)pkt->p_peer)->sin_addr),
pkt->p_substds);
#else
char subst[IPSIZE];
if (getnameinfo(pkt->p_peer, pkt->p_peerlen,
subst, NI_MAXHOST, NULL, 0, NI_NUMERICHOST) != 0)
subst[0] = '\0';
addrr_a_txt(pkt, qi->qi_tflag, pkt->p_substrr, subst, pkt->p_substds);
#endif
}
/* now complete the reply: add AUTH etc sections */
/* addrr_ns(auth=1) should be called last as it fills in
* both AUTH and ADDITIONAL sections */
if (!found) { /* negative result */
addrr_soa(pkt, zone, 1); /* add SOA if any to AUTHORITY */
h[p_f2] = DNS_R_NXDOMAIN;
do_stats(zone->z_stats.q_nxd += 1);
}
else {
if (!h[p_ancnt2]) { /* positive reply, no answers */
addrr_soa(pkt, zone, 1); /* add SOA if any to AUTHORITY */
}
else if (zone->z_nns &&
/* (!(qi->qi_tflag & NSQUERY_NS) || qi->qi_dnlab) && */
!lazy)
addrr_ns(pkt, zone, 1); /* add nameserver records to positive reply */
do_stats(zone->z_stats.q_ok += 1);
}
(void)call_hook(query_result, (pkt->p_peer, zone, qi, found));
if (rlen() > DNS_MAXPACKET) { /* add OPT record for long replies */
/* as per parsequery(), we always have 11 bytes for minimal OPT record at
* the end of our reply packet, OR rlen() does not exceed DNS_MAXPACKET */
h[p_arcnt2] += 1; /* arcnt is limited to 254 records */
h = pkt->p_cur;
*h++ = 0; /* empty (root) DN */
PACK16S(h, DNS_T_OPT);
PACK16S(h, DNS_EDNS0_MAXPACKET);
*h++ = 0; *h++ = 0; /* RCODE and version */
*h++ = 0; *h++ = 0; /* rest of the TTL field */
*h++ = 0; *h++ = 0; /* RDLEN */
pkt->p_cur = h;
h = pkt->p_buf; /* restore for rlen() to work */
}
do_stats(zone->z_stats.b_out += rlen());
return rlen();
err_nz:
do_stats(gstats.q_err += 1; gstats.b_in += qlen; gstats.b_out += rlen());
return rlen();
err_z:
do_stats(zone->z_stats.q_err += 1; zone->z_stats.b_out += rlen());
return rlen();
}
#define fit(pkt, c, bytes) ((c) + (bytes) <= (pkt)->p_endp)
/* DN compression pointers/structures */
/* We store pre-computed RRs for NS and SOA records in special
* cache buffers referenced to by zone structure.
*
* The precomputed RRs consists of ready-to-be-sent data (with
* all record types/classes, TTLs, and data in place), modulo
* compressed DN backreferences. When this cached data will be
* copied into answer packet, we'll need to adjust "jumps" in
* DN name compressions to reflect actual position of the data
* in answer packet.
*
* Cache data is calculated as if it where inside some packet,
* where it's start is exactly at the beginning of cached/precomputed
* record, and with zone's base DN (with class and type) being in
* question section immediately BEFORE the data (i.e. before our
* "virtual packet"). So some DN compression offsets (pointers)
* will be negative (referring to the query section of actual answer,
* as zone base DN will be present in answer anyway), and some will
* be positive (referring to this very record in actual answer).
*/
struct dnjump { /* one DN "jump": */
unsigned char *pos; /* position in precomputed packet where the jump is */
int off; /* jump offset relative to beginning of the RRs */
};
struct dnptr { /* domain pointer for DN compression */
const unsigned char *dn; /* actual (complete) domain name */
int off; /* jump offset relative to start of RRs */
};
struct dncompr { /* DN compression structure */
struct dnptr ptr[256]; /* array of all known domain names */
struct dnptr *lptr; /* last unused slot in ptr[] */
unsigned char *buf; /* buffer for the cached RRs */
unsigned char *bend; /* pointer to past the end of buf */
struct dnjump *jump; /* current jump ptr (array of jumps) */
};
#define CACHEBUF_SIZE (DNS_MAXPACKET-p_hdrsize-4)
/* maxpacket minus header minus (class+type) */
/* initialize compression/cache structures */
static unsigned char *
dnc_init(struct dncompr *compr,
unsigned char *buf, unsigned bufsize, struct dnjump *jump,
const unsigned char *dn) {
struct dnptr *ptr;
unsigned char *cpos;
compr->buf = buf; compr->bend = buf + bufsize;
compr->jump = jump;
cpos = buf - dns_dnlen(dn) - 4; /* current position: qDN BEFORE the RRs */
ptr = compr->ptr;
while(*dn) {
ptr->dn = dn;
ptr->off = cpos - buf;
++ptr;
cpos += *dn + 1;
dn += *dn + 1;
}
compr->lptr = ptr;
return cpos + 5;
}
/* add one DN into cache, adjust compression pointers and current pointer */
static unsigned char *
dnc_add(struct dncompr *compr, unsigned char *cpos, const unsigned char *dn) {
struct dnptr *ptr;
while(*dn) {
/* lookup DN in already stored names */
for(ptr = compr->ptr; ptr < compr->lptr; ++ptr) {
if (!dns_dnequ(ptr->dn, dn))
continue;
/* found one, make a jump to it */
if (cpos + 2 >= compr->bend) return NULL;
compr->jump->pos = cpos;
compr->jump->off = ptr->off;
++compr->jump;
return cpos + 2;
}
/* not found, add it to the list of known DNs... */
if (cpos + *dn + 1 >= compr->bend)
return NULL; /* does not fit */
if (ptr < compr->ptr + sizeof(compr->ptr) / sizeof(compr->ptr[0])) {
ptr->dn = dn;
ptr->off = cpos - compr->buf;
++compr->lptr;
}
/* ...and add one label into the "packet" */
memcpy(cpos, dn, *dn + 1);
cpos += *dn + 1;
dn += *dn + 1;
}
if (cpos + 1 >= compr->bend)
return NULL;
*cpos++ = '\0';
return cpos;
}
/* finalize RRs: remember it's size and number of jumps */
static void dnc_finish(struct dncompr *compr, unsigned char *cptr,
unsigned *sizep, struct dnjump **jendp) {
*sizep = cptr - compr->buf;
*jendp = compr->jump;
}
/* place pre-cached RRs into the packet, adjusting jumps */
static int
dnc_final(struct dnspacket *pkt,
const unsigned char *data, unsigned dsize,
const struct dnjump *jump,
const struct dnjump *jend) {
const unsigned qoff = (pkt->p_sans - pkt->p_buf) + 0xc000;
const unsigned coff = (pkt->p_cur - pkt->p_buf) + 0xc000;
unsigned pos;
if (!fit(pkt, pkt->p_cur, dsize))
return 0;
/* first, adjust offsets - in cached data anyway */
while(jump < jend) {
/* jump to either query section or this very RRs */
pos = jump->off + (jump->off < 0 ? qoff : coff);
PACK16(jump->pos, pos);
++jump;
}
/* and finally, copy the RRs into answer packet */
memcpy(pkt->p_cur, data, dsize);
pkt->p_cur += dsize;
return 1;
}
struct zonesoa { /* cached SOA RR */
unsigned size; /* size of the RR */
unsigned ttloff; /* offset of the TTL field */
const unsigned char *minttl; /* pointer to minttl in data */
struct dnjump jump[3]; /* jumps to fix: 3 max (qdn, odn, pdn) */
struct dnjump *jend; /* last jump */
unsigned char data[CACHEBUF_SIZE];
};
struct zonens { /* cached NS RRs */
unsigned nssize; /* size of all NS RRs */
unsigned tsize; /* size of NS+glue recs */
struct dnjump jump[MAX_NS*2+MAX_GLUE];/* jumps: for qDNs and for NSes */
struct dnjump *nsjend; /* last NS jump */
struct dnjump *tjend; /* last glue jump */
unsigned char data[CACHEBUF_SIZE];
};
void init_zones_caches(struct zone *zonelist) {
while(zonelist) {
if (!zonelist->z_dsl) {
char name[DNS_MAXDOMAIN];
dns_dntop(zonelist->z_dn, name, sizeof(name));
error(0, "missing data for zone `%s'", name);
}
zonelist->z_zsoa = tmalloc(struct zonesoa);
/* for NS RRs, we allocate MAX_NS caches:
* each stores one variant of NS rotation */
zonelist->z_zns = (struct zonens *)emalloc(sizeof(struct zonens) * MAX_NS);
zonelist = zonelist->z_next;
}
}
/* update SOA RR cache */
int update_zone_soa(struct zone *zone, const struct dssoa *dssoa) {
struct zonesoa *zsoa;
unsigned char *cpos;
struct dncompr compr;
unsigned t;
unsigned char *sizep;
zsoa = zone->z_zsoa;
zsoa->size = 0;
if (!(zone->z_dssoa = dssoa)) return 1;
cpos = dnc_init(&compr, zsoa->data, sizeof(zsoa->data),
zsoa->jump, zone->z_dn);
cpos = dnc_add(&compr, cpos, zone->z_dn);
PACK16S(cpos, DNS_T_SOA);
PACK16S(cpos, DNS_C_IN);
zsoa->ttloff = cpos - compr.buf;
PACK32S(cpos, dssoa->dssoa_ttl);
sizep = cpos;
cpos += 2;
cpos = dnc_add(&compr, cpos, dssoa->dssoa_odn);
if (!cpos) return 0;
cpos = dnc_add(&compr, cpos, dssoa->dssoa_pdn);
if (!cpos) return 0;
t = dssoa->dssoa_serial ? dssoa->dssoa_serial : zone->z_stamp;
PACK32S(cpos, t);
memcpy(cpos, dssoa->dssoa_n, 16); cpos += 16;
zsoa->minttl = cpos - 4;
t = cpos - sizep - 2;
PACK16(sizep, t);
dnc_finish(&compr, cpos, &zsoa->size, &zsoa->jend);
return 1;
}
static int addrr_soa(struct dnspacket *pkt, const struct zone *zone, int auth) {
const struct zonesoa *zsoa = zone->z_zsoa;
unsigned char *c = pkt->p_cur;
if (!zone->z_dssoa || !zsoa->size) {
if (!auth)
setnonauth(pkt->p_buf);
return 0;
}
if (!dnc_final(pkt, zsoa->data, zsoa->size, zsoa->jump, zsoa->jend)) {
if (!auth)
setnonauth(pkt->p_buf); /* non-auth answer as we can't fit the record */
return 0;
}
/* for AUTHORITY section for NXDOMAIN etc replies, use minttl as TTL */
if (auth) memcpy(c + zsoa->ttloff, zsoa->minttl, 4);
pkt->p_buf[auth ? p_nscnt2 : p_ancnt2]++;
return 1;
}
static unsigned char *
find_glue(struct zone *zone, const unsigned char *nsdn,
struct dnspacket *pkt, const struct zone *zonelist) {
struct dnsqinfo qi;
unsigned lab;
unsigned char dnbuf[DNS_MAXDN], *dp;
unsigned char *dnlptr[DNS_MAXLABELS];
const struct dslist *dsl;
const struct zone *qzone;
/* lowercase the nsdn and find label pointers */
lab = 0; dp = dnbuf;
while((*dp = *nsdn)) {
const unsigned char *e = nsdn + *nsdn + 1;
dnlptr[lab++] = dp++;
while(++nsdn < e)
*dp++ = dns_dnlc(*nsdn);
}
qzone = findqzone(zonelist, dp - dnbuf + 1, lab, dnlptr, &qi);
if (!qzone)
return NULL;
/* pefrorm fake query */
qi.qi_tflag = NSQUERY_A/*|NSQUERY_AAAA*/;
dp = pkt->p_cur;
for(dsl = qzone->z_dsl; dsl; dsl = dsl->dsl_next)
dsl->dsl_queryfn(dsl->dsl_ds, &qi, pkt);
if (dp == pkt->p_cur) {
char name[DNS_MAXDOMAIN];
dns_dntop(qi.qi_dn, name, sizeof(name));
zlog(LOG_WARNING, zone, "no glue record(s) for %.60s NS found", name);
return NULL;
}
return dp;
}
int update_zone_ns(struct zone *zone, const struct dsns *dsns, unsigned ttl,
const struct zone *zonelist) {
struct zonens *zns;
unsigned char *cpos, *sizep;
struct dncompr compr;
unsigned size, i, ns, nns;
const unsigned char *nsdna[MAX_NS];
const unsigned char *dn;
unsigned char *nsrrs[MAX_NS], *nsrre[MAX_NS];
unsigned nglue;
struct dnspacket pkt;
memset(&pkt, 0, sizeof(pkt));
pkt.p_sans = pkt.p_cur = pkt.p_buf + p_hdrsize;
pkt.p_endp = pkt.p_buf + CACHEBUF_SIZE + p_hdrsize;
for(nns = 0; dsns; dsns = dsns->dsns_next) {
i = 0;
while(i < nns && !dns_dnequ(nsdna[i], dsns->dsns_dn))
++i;
if (i < nns)
continue;
if (nns >= MAX_NS) {
zlog(LOG_WARNING, zone,
"too many NS records specified, only first %d will be used", MAX_NS);
break;
}
nsdna[nns] = dsns->dsns_dn;
if ((nsrrs[nns] = find_glue(zone, dsns->dsns_dn, &pkt, zonelist)))
nsrre[nns] = pkt.p_cur;
++nns;
}
/* number of additional records must not exceed 254: (room for EDNS0 OPT) */
nglue = pkt.p_buf[p_ancnt2];
if (pkt.p_buf[p_ancnt1] || nglue > 254) /* too many glue recs */
return 0;
/* check if we have enouth dnjump slots */
if (nns * 2 + nglue > sizeof(zns->jump)/sizeof(zns->jump[0]))
return 0;
memcpy(zone->z_nsdna, nsdna, nns * sizeof(nsdna[0]));
memset(nsdna + nns, 0, (MAX_NS - nns) * sizeof(nsdna[0]));
zone->z_nns = 0; /* for now, in case of error return */
zone->z_nsttl = ttl;
/* fill up nns variants of NS RRs ordering:
* zns is actually an array, not single structure */
ns = 0;
zns = zone->z_zns;
for(;;) {
cpos = dnc_init(&compr, zns->data, sizeof(zns->data),
zns->jump, zone->z_dn);
for(i = 0; i < nns; ++i) {
cpos = dnc_add(&compr, cpos, zone->z_dn);
if (!cpos || cpos + 10 > compr.bend) return 0;
PACK16S(cpos, DNS_T_NS);
PACK16S(cpos, DNS_C_IN);
PACK32S(cpos, ttl);
sizep = cpos; cpos += 2;
cpos = dnc_add(&compr, cpos, nsdna[i]);
if (!cpos) return 0;
size = cpos - sizep - 2;
PACK16(sizep, size);
}
dnc_finish(&compr, cpos, &zns->nssize, &zns->nsjend);
if (nglue)
for(i = 0; i < nns; ++i)
for(dn = nsrrs[i]; dn && dn < nsrre[i]; ) {
/* pack the glue record. dnjump, type+class, ttl, size (= 4 or 16) */
dn += 2;
size = 10 + dn[2+2+4+1];
cpos = dnc_add(&compr, cpos, zone->z_nsdna[i]);
if (!cpos || cpos + size > compr.bend) return 0;
memcpy(cpos, dn, size);
dn += size; cpos += size;
}
dnc_finish(&compr, cpos, &zns->tsize, &zns->tjend);
if (++ns >= nns) break;
/* rotate list of NSes */
dn = nsdna[0];
memmove(nsdna, nsdna + 1, (nns - 1) * sizeof(nsdna[0]));
nsdna[nns - 1] = dn;
++zns;
}
zone->z_nns = nns;
zone->z_nglue = nglue;
return 1;
}
static int addrr_ns(struct dnspacket *pkt, const struct zone *zone, int auth) {
unsigned cns = zone->z_cns;
const struct zonens *zns = zone->z_zns + cns;
if (!zone->z_nns)
return 0;
/* if auth=1, we're adding last records (except maybe EDNS0 OPT),
* so it's ok to fill in both AUTH and ADDITIONAL sections. */
/* If we can't fit both NS and glue recs, try NS only, omitting glue.
* For auth=0, don't add glue records at all. */
if (auth && dnc_final(pkt, zns->data, zns->tsize, zns->jump, zns->tjend)) {
pkt->p_buf[p_nscnt2] += zone->z_nns;
pkt->p_buf[p_arcnt2] += zone->z_nglue;
}
else if (!dnc_final(pkt, zns->data, zns->nssize, zns->jump, zns->nsjend))
return 0;
else
/* we can't overflow p_ancnt2 (255 max) because addrr_ns(auth=0)
* is called before all other answers will be collected,
* and MAX_NS (zone->z_nns) is definitely less than 255 */
pkt->p_buf[auth ? p_nscnt2 : p_ancnt2] += zone->z_nns;
/* pick up next variation of NS ordering */
++cns;
if (cns >= zone->z_nns)
cns = 0;
((struct zone *)zone)->z_cns = cns;
return 1;
}
static unsigned
checkrr_present(register unsigned char *c, register unsigned char *e,
unsigned dtp, const void *data, unsigned dsz, unsigned ttl) {
/* check whenever we already have this (type of) RR in reply,
* ensure that all RRs of the same type has the same TTL */
const unsigned char dtp1 = dtp >> 8, dtp2 = dtp & 255;
unsigned t;
#define nextRR(c) ((c) + 12 + (c)[11])
#define hasRR(c,e) ((c) < (e))
#define sameRRT(c,dtp1,dtp2) ((c)[2] == (dtp1) && (c)[3] == (dtp2))
#define sameDATA(c,dsz,data) \
((c)[11] == (dsz) && memcmp((c)+12, (data), (dsz)) == 0)
#define rrTTL(c) ((c)+6)
for(;;) {
if (!hasRR(c,e))
return ttl;
if (sameRRT(c,dtp1,dtp2))
break;
c = nextRR(c);
}
/* found at least one RR with the same type as new */
if (ttl >= (t = unpack32(rrTTL(c)))) {
/* new ttl is either larger or the same as ttl of one of existing RRs */
/* if we already have the same record, do nothing */
if (sameDATA(c,dsz,data))
return 0;
/* check other records too */
for(c = nextRR(c); hasRR(c,e); c = nextRR(c))
if (sameRRT(c,dtp1,dtp2) && sameDATA(c,dsz,data))
/* already has exactly the same data */
return 0;
return t; /* use existing, smaller TTL for new RR */
}
else { /* change TTLs of existing RRs to new, smaller one */
int same = sameDATA(c,dsz,data);
unsigned char *ttlnb = rrTTL(c);
PACK32(ttlnb, ttl);
for(c = nextRR(c); hasRR(c,e); c = nextRR(c))
if (sameRRT(c,dtp1,dtp2)) {
memcpy(rrTTL(c), ttlnb, 4);
if (sameDATA(c,dsz,data))
same = 1;
}
return same ? 0 : ttl;
}
#undef nextRR
#undef hasRR
#undef sameRRT
#undef sameDATA
#undef rrTTL
}
/* add a new record into answer, check for dups.
* We just ignore any data that exceeds packet size */
void addrr_any(struct dnspacket *pkt, unsigned dtp,
const void *data, unsigned dsz,
unsigned ttl) {
register unsigned char *c = pkt->p_cur;
ttl = checkrr_present(pkt->p_sans, c, dtp, data, dsz, ttl);
if (!ttl) return; /* if RR is already present, do nothing */
if (!fit(pkt, c, 12 + dsz) || pkt->p_buf[p_ancnt2] == 255) {
setnonauth(pkt->p_buf); /* non-auth answer as we can't fit the record */
return;
}
*c++ = 192; *c++ = p_hdrsize; /* jump after header: query DN */
PACK16S(c, dtp);
PACK16S(c, DNS_C_IN);
PACK32S(c, ttl);
PACK16S(c, dsz);
memcpy(c, data, dsz);
pkt->p_cur = c + dsz;
pkt->p_buf[p_ancnt2] += 1; /* increment numanswers */
}
void
addrr_a_txt(struct dnspacket *pkt, unsigned qtflag,
const char *rr, const char *subst,
const struct dataset *ds) {
if (qtflag & NSQUERY_A)
addrr_any(pkt, DNS_T_A, rr, 4, ds->ds_ttl);
if (qtflag & NSQUERY_TXT) {
char sb[TXTBUFSIZ+1];
unsigned sl = txtsubst(sb + 1, rr + 4, subst, ds);
if (sl) {
sb[0] = sl;
addrr_any(pkt, DNS_T_TXT, sb, sl + 1, ds->ds_ttl);
}
}
}
static int version_req(struct dnspacket *pkt, const struct dnsquery *qry) {
register unsigned char *c;
unsigned dsz;
if (!show_version)
return 0;
if (qry->q_class != DNS_C_CH || qry->q_type != DNS_T_TXT)
return 0;
if ((qry->q_dnlen != 16 || memcmp(qry->q_dn, "\7version\6server", 16)) &&
(qry->q_dnlen != 14 || memcmp(qry->q_dn, "\7version\4bind", 14)))
return 0;
c = pkt->p_cur;
*c++ = 192; *c++ = p_hdrsize; /* jump after header: query DN */
*c++ = DNS_T_TXT>>8; *c++ = DNS_T_TXT;
*c++ = DNS_C_CH>>8; *c++ = DNS_C_CH;
*c++ = 0; *c++ = 0; *c++ = 0; *c++ = 0; /* ttl */
dsz = strlen(show_version) + 1;
PACK16(c, dsz); c += 2; /* dsize */
*c++ = --dsz;
memcpy(c, show_version, dsz);
pkt->p_cur = c + dsz;
pkt->p_buf[p_ancnt2] += 1; /* increment numanswers */
return 1;
}
void logreply(const struct dnspacket *pkt, FILE *flog,
int flushlog, const struct dnsqinfo *qi, unsigned reply_len) {
char cbuf[DNS_MAXDOMAIN + IPSIZE + 51 + DNS_MAXLABEL];
char *cp = cbuf;
const unsigned char *const q = pkt->p_sans - 4;