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NetBSD/usr.sbin/bind/named/ns_forw.c

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/* $NetBSD: ns_forw.c,v 1.1.1.1 1998/10/05 18:02:00 tron Exp $ */
#if !defined(lint) && !defined(SABER)
static char sccsid[] = "@(#)ns_forw.c 4.32 (Berkeley) 3/3/91";
static char rcsid[] = "Id: ns_forw.c,v 8.34 1998/02/24 01:02:40 halley Exp";
#endif /* not lint */
/*
* Copyright (c) 1986
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* Portions Copyright (c) 1993 by Digital Equipment Corporation.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies, and that
* the name of Digital Equipment Corporation not be used in advertising or
* publicity pertaining to distribution of the document or software without
* specific, written prior permission.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
/*
* Portions Copyright (c) 1996, 1997 by Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
* SOFTWARE.
*/
#include "port_before.h"
#include <sys/types.h>
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <resolv.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <isc/eventlib.h>
#include <isc/logging.h>
#include <isc/memcluster.h>
#include "port_after.h"
#include "named.h"
struct complaint {
u_long tag1, tag2;
time_t expire;
struct complaint *next;
};
static struct complaint *complaints = NULL;
static int retry_timer_set = 0;
/*
* Forward the query to get the answer since its not in the database.
* Returns FW_OK if a request struct is allocated and the query sent.
* Returns FW_DUP if this is a duplicate of a pending request.
* Returns FW_NOSERVER if there were no addresses for the nameservers.
* Returns FW_SERVFAIL on memory allocation error or if asked to do something
* dangerous, such as fwd to ourselves or fwd to the host that asked us.
*
* (no action is taken on errors and qpp is not filled in.)
*/
int
ns_forw(struct databuf *nsp[], u_char *msg, int msglen,
struct sockaddr_in from, struct qstream *qsp, int dfd,
struct qinfo **qpp, const char *dname, int class, int type,
struct namebuf *np, int use_tcp)
{
struct qinfo *qp;
char tmpdomain[MAXDNAME];
struct sockaddr_in *nsa;
HEADER *hp;
u_int16_t id;
int n;
ns_debug(ns_log_default, 3, "ns_forw()");
hp = (HEADER *) msg;
id = hp->id;
/* Look at them all */
for (qp = nsqhead; qp != NULL; qp = qp->q_link) {
if (qp->q_id == id &&
memcmp(&qp->q_from, &from, sizeof qp->q_from) == 0 &&
((qp->q_cmsglen == 0 && qp->q_msglen == msglen &&
memcmp(qp->q_msg + 2, msg + 2, msglen - 2) == 0) ||
(qp->q_cmsglen == msglen &&
memcmp(qp->q_cmsg + 2, msg + 2, msglen - 2) == 0)
)) {
ns_debug(ns_log_default, 3, "forw: dropped DUP id=%d",
ntohs(id));
nameserIncr(from.sin_addr, nssRcvdDupQ);
return (FW_DUP);
}
}
qp = qnew(dname, class, type);
getname(np, tmpdomain, sizeof tmpdomain);
qp->q_domain = savestr(tmpdomain, 1);
qp->q_from = from; /* nslookup wants to know this */
n = nslookup(nsp, qp, dname, "ns_forw");
if (n < 0) {
ns_debug(ns_log_default, 2, "forw: nslookup reports danger");
ns_freeqry(qp);
return (FW_SERVFAIL);
}
if (n == 0 && !server_options->fwdtab) {
ns_debug(ns_log_default, 2, "forw: no nameservers found");
ns_freeqry(qp);
return (FW_NOSERVER);
}
qp->q_stream = qsp;
qp->q_curaddr = 0;
qp->q_fwd = server_options->fwdtab;
qp->q_dfd = dfd;
qp->q_id = id;
qp->q_expire = tt.tv_sec + RETRY_TIMEOUT*2;
if (use_tcp)
qp->q_flags |= Q_USEVC;
hp->id = qp->q_nsid = htons(nsid_next());
hp->ancount = htons(0);
hp->nscount = htons(0);
hp->arcount = htons(0);
if ((qp->q_msg = (u_char *)memget((unsigned)msglen)) == NULL) {
ns_notice(ns_log_default, "forw: memget: %s",
strerror(errno));
ns_freeqry(qp);
return (FW_SERVFAIL);
}
qp->q_msgsize = msglen;
memcpy(qp->q_msg, msg, qp->q_msglen = msglen);
if (!qp->q_fwd) {
hp->rd = 0;
qp->q_addr[0].stime = tt;
}
#ifdef SLAVE_FORWARD
if (NS_OPTION_P(OPTION_FORWARD_ONLY))
schedretry(qp, (time_t)slave_retry);
else
#endif /* SLAVE_FORWARD */
schedretry(qp, qp->q_fwd ?(2*RETRYBASE) :retrytime(qp));
nsa = Q_NEXTADDR(qp, 0);
ns_debug(ns_log_default, 1,
"forw: forw -> [%s].%d ds=%d nsid=%d id=%d %dms retry %dsec",
inet_ntoa(nsa->sin_addr),
ntohs(nsa->sin_port), ds,
ntohs(qp->q_nsid), ntohs(qp->q_id),
(qp->q_addr[0].nsdata != NULL)
? qp->q_addr[0].nsdata->d_nstime
: -1,
(int)(qp->q_time - tt.tv_sec));
#ifdef DEBUG
if (debug >= 10)
fp_nquery(msg, msglen, log_get_stream(packet_channel));
#endif
if (qp->q_flags & Q_USEVC) {
if (tcp_send(qp) != NOERROR) {
if (!haveComplained(ina_ulong(nsa->sin_addr),
(u_long)tcpsendStr))
ns_info(ns_log_default,
"ns_forw: tcp_send(%s) failed: %s",
sin_ntoa(*nsa), strerror(errno));
}
} else if (sendto(ds, (char *)msg, msglen, 0, (struct sockaddr *)nsa,
sizeof(struct sockaddr_in)) < 0) {
if (!haveComplained(ina_ulong(nsa->sin_addr),
(u_long)sendtoStr))
ns_info(ns_log_default, "ns_forw: sendto(%s): %s",
sin_ntoa(*nsa), strerror(errno));
nameserIncr(nsa->sin_addr, nssSendtoErr);
}
if (NS_OPTION_P(OPTION_HOSTSTATS))
nameserIncr(from.sin_addr, nssRcvdFwdQ);
nameserIncr(nsa->sin_addr, nssSentFwdQ);
if (qpp)
*qpp = qp;
hp->rd = 1;
return (0);
}
/* haveComplained(tag1, tag2)
* check to see if we have complained about (tag1,tag2) recently
* returns:
* boolean: have we complained recently?
* side-effects:
* outdated complaint records removed from our static list
* author:
* Paul Vixie (DECWRL) April 1991
*/
int
haveComplained(u_long tag1, u_long tag2) {
struct complaint *cur, *next, *prev;
int r = 0;
for (cur = complaints, prev = NULL;
cur != NULL;
prev = cur, cur = next) {
next = cur->next;
if (tt.tv_sec > cur->expire) {
if (prev)
prev->next = next;
else
complaints = next;
memput(cur, sizeof *cur);
cur = prev;
} else if (tag1 == cur->tag1 && tag2 == cur->tag2)
r++;
}
if (!r) {
cur = (struct complaint *)memget(sizeof(struct complaint));
if (cur) {
cur->tag1 = tag1;
cur->tag2 = tag2;
cur->expire = tt.tv_sec + INIT_REFRESH; /* "10:00" */
cur->next = NULL;
if (prev)
prev->next = cur;
else
complaints = cur;
}
}
return (r);
}
void
freeComplaints(void) {
struct complaint *cur, *next;
for (cur = complaints; cur != NULL; cur = next) {
next = cur->next;
memput(cur, sizeof *cur);
}
complaints = NULL;
}
/* void
* nslookupComplain(sysloginfo, queryname, complaint, dname, a_rr)
* Issue a complaint about a dangerous situation found by nslookup().
* params:
* sysloginfo is a string identifying the complainant.
* queryname is the domain name associated with the problem.
* complaint is a string describing what is wrong.
* dname and a_rr are the problematic other name server.
*/
static void
nslookupComplain(const char *sysloginfo, const char *queryname,
const char *complaint, const char *dname,
const struct databuf *a_rr, const struct databuf *nsdp)
{
char *a, *ns;
const char *a_type;
int print_a;
ns_debug(ns_log_default, 2, "NS '%s' %s", dname, complaint);
if (sysloginfo && queryname && !haveComplained((u_long)queryname,
(u_long)complaint)) {
char buf[999];
a = ns = (char *)NULL;
print_a = (a_rr->d_type == T_A);
a_type = p_type(a_rr->d_type);
if (a_rr->d_rcode) {
print_a = 0;
switch(a_rr->d_rcode) {
case NXDOMAIN:
a_type = "NXDOMAIN";
break;
case NOERROR_NODATA:
a_type = "NODATA";
break;
}
}
if (NS_OPTION_P(OPTION_HOSTSTATS)) {
char nsbuf[20], abuf[20];
if (nsdp != NULL) {
if (nsdp->d_ns != NULL) {
strcpy(nsbuf,
inet_ntoa(nsdp->d_ns->addr));
ns = nsbuf;
} else {
ns = zones[nsdp->d_zone].z_origin;
}
}
if (a_rr->d_ns != NULL) {
strcpy(abuf, inet_ntoa(a_rr->d_ns->addr));
a = abuf;
} else {
a = zones[a_rr->d_zone].z_origin;
}
}
if (a != NULL || ns != NULL)
ns_info(ns_log_default,
"%s: query(%s) %s (%s:%s) learnt (%s=%s:NS=%s)",
sysloginfo, queryname,
complaint, dname,
print_a ?
inet_ntoa(ina_get(a_rr->d_data)) : "",
a_type,
a ? a : "<Not Available>",
ns ? ns : "<Not Available>" );
else
ns_info(ns_log_default, "%s: query(%s) %s (%s:%s)",
sysloginfo, queryname,
complaint, dname,
print_a ?
inet_ntoa(ina_get(a_rr->d_data)) : "");
}
}
/*
* nslookup(nsp, qp, syslogdname, sysloginfo)
* Lookup the address for each nameserver in `nsp' and add it to
* the list saved in the qinfo structure pointed to by `qp'.
* Omits information about nameservers that we shouldn't ask.
* Detects the following dangerous operations:
* One of the A records for one of the nameservers in nsp
* refers to the address of one of our own interfaces;
* One of the A records refers to the nameserver port on
* the host that asked us this question.
* returns: the number of addresses added, or -1 if a dangerous operation
* is detected.
* side effects:
* logs if a dangerous situation is detected and
* (syslogdname && sysloginfo)
*/
int
nslookup(struct databuf *nsp[], struct qinfo *qp,
const char *syslogdname, const char *sysloginfo)
{
struct namebuf *np;
struct databuf *dp, *nsdp;
struct qserv *qs;
int n;
u_int i;
struct hashbuf *tmphtp;
char *dname;
const char *fname;
int oldn, naddr, class, found_arr, potential_ns;
time_t curtime;
ns_debug(ns_log_default, 3, "nslookup(nsp=%#x, qp=%#x, \"%s\")",
nsp, qp, syslogdname);
potential_ns = 0;
naddr = n = qp->q_naddr;
curtime = (u_long) tt.tv_sec;
while ((nsdp = *nsp++) != NULL) {
class = nsdp->d_class;
dname = (char *)nsdp->d_data;
ns_debug(ns_log_default, 3,
"nslookup: NS \"%s\" c=%d t=%d (flags 0x%lu)",
dname, class, nsdp->d_type, (u_long)nsdp->d_flags);
/* don't put in servers we have tried */
for (i = 0; i < qp->q_nusedns; i++) {
if (qp->q_usedns[i] == nsdp) {
ns_debug(ns_log_default, 2,
"skipping used NS w/name %s",
nsdp->d_data);
goto skipserver;
}
}
tmphtp = ((nsdp->d_flags & DB_F_HINT) ?fcachetab :hashtab);
np = nlookup(dname, &tmphtp, &fname, 1);
if (np == NULL) {
ns_debug(ns_log_default, 3, "%s: not found %s %#x",
dname, fname, np);
found_arr = 0;
goto need_sysquery;
}
if (fname != dname) {
if (findMyZone(np, class) == DB_Z_CACHE) {
/*
* lifted from findMyZone()
* We really need to know if the NS
* is the bottom of one of our zones
* to see if we've got missing glue
*/
for (; np; np = np_parent(np))
for (dp = np->n_data; dp; dp = dp->d_next)
if (match(dp, class, T_NS)) {
if (dp->d_rcode)
break;
if (dp->d_zone) {
static char *complaint =
"Glue A RR missing";
nslookupComplain(sysloginfo,
syslogdname,
complaint,
dname, dp,
nsdp);
goto skipserver;
} else {
found_arr = 0;
goto need_sysquery;
}
}
/* shouldn't happen, but ... */
found_arr = 0;
goto need_sysquery;
} else {
/* Authoritative A RR missing. */
continue;
}
}
found_arr = 0;
oldn = n;
/* look for name server addresses */
delete_stale(np);
for (dp = np->n_data; dp != NULL; dp = dp->d_next) {
struct in_addr nsa;
if (dp->d_type == T_CNAME && dp->d_class == class) {
static const char *complaint =
"NS points to CNAME";
if (dp->d_rcode)
continue;
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
goto skipserver;
}
if (dp->d_type != T_A || dp->d_class != class)
continue;
if (dp->d_rcode) {
static const char *complaint =
"A RR negative cache entry";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
goto skipserver;
}
if (ina_hlong(ina_get(dp->d_data)) == INADDR_ANY) {
static const char *complaint =
"Bogus (0.0.0.0) A RR";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
#ifdef INADDR_LOOPBACK
if (ina_hlong(ina_get(dp->d_data))==INADDR_LOOPBACK) {
static const char *complaint =
"Bogus LOOPBACK A RR";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
#endif
#ifdef INADDR_BROADCAST
if (ina_hlong(ina_get(dp->d_data))==INADDR_BROADCAST){
static const char *complaint =
"Bogus BROADCAST A RR";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
#endif
#ifdef IN_MULTICAST
if (IN_MULTICAST(ina_hlong(ina_get(dp->d_data)))) {
static const char *complaint =
"Bogus MULTICAST A RR";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
#endif
/*
* Don't use records that may become invalid to
* reference later when we do the rtt computation.
* Never delete our safety-belt information!
*/
if ((dp->d_zone == DB_Z_CACHE) &&
(dp->d_ttl < (u_int32_t)curtime) &&
!(dp->d_flags & DB_F_HINT) )
{
ns_debug(ns_log_default, 1,
"nslookup: stale '%s'",
NAME(*np));
n = oldn;
found_arr = 0;
goto need_sysquery;
}
found_arr++;
nsa = ina_get(dp->d_data);
/* don't put in duplicates */
qs = qp->q_addr;
for (i = 0; i < (u_int)n; i++, qs++)
if (ina_equal(qs->ns_addr.sin_addr, nsa))
goto skipaddr;
qs->ns_addr.sin_family = AF_INET;
qs->ns_addr.sin_port = ns_port;
qs->ns_addr.sin_addr = nsa;
qs->ns = nsdp;
qs->nsdata = dp;
qs->nretry = 0;
/*
* If this A RR has no RTT, initialize its RTT to a
* small random value.
*/
if (dp->d_nstime == 0)
dp->d_nstime = 1 +
(int)(25.0*rand()/(RAND_MAX + 1.0));
/*
* if we are being asked to fwd a query whose
* nameserver list includes our own name/address(es),
* then we have detected a lame delegation and rather
* than melt down the network and hose down the other
* servers (who will hose us in return), we'll return
* -1 here which will cause SERVFAIL to be sent to
* the client's resolver which will hopefully then
* shut up.
*
* (originally done in nsContainsUs by vix@dec mar92;
* moved into nslookup by apb@und jan1993)
*
* try to limp along instead of denying service
* gdonl mar96
*/
if (aIsUs(nsa)) {
static char *complaint = "contains our address";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
/*
* If we want to forward to a host that asked us
* this question then either we or they are sick
* (unless they asked from some port other than
* their nameserver port). (apb@und jan1993)
*
* try to limp along instead of denying service
* gdonl mar96
*/
if (memcmp(&qp->q_from, &qs->ns_addr,
sizeof(qp->q_from)) == 0)
{
static char *complaint = "forwarding loop";
nslookupComplain(sysloginfo, syslogdname,
complaint, dname, dp, nsdp);
continue;
}
#ifdef BOGUSNS
/*
* Don't forward queries to bogus servers. Note
* that this is unlike the previous tests, which
* are fatal to the query. Here we just skip the
* server, which is only fatal if it's the last
* server. Note also that we antialias here -- all
* A RR's of a server are considered the same server,
* and if any of them is bogus we skip the whole
* server. Those of you using multiple A RR's to
* load-balance your servers will (rightfully) lose
* here. But (unfortunately) only if they are bogus.
*/
if (ip_match_address(bogus_nameservers, nsa) > 0)
goto skipserver;
#endif
n++;
if (n >= NSMAX)
goto out;
skipaddr:
(void)NULL;
}
ns_debug(ns_log_default, 8, "nslookup: %d ns addrs", n);
need_sysquery:
if (found_arr == 0) {
potential_ns++;
if (!(qp->q_flags & Q_SYSTEM))
(void) sysquery(dname, class, T_A, NULL, 0,
QUERY);
}
skipserver:
(void)NULL;
}
out:
ns_debug(ns_log_default, 3, "nslookup: %d ns addrs total", n);
qp->q_naddr = n;
if (n == 0 && potential_ns == 0 && !server_options->fwdtab) {
static char *complaint = "No possible A RRs";
if (sysloginfo && syslogdname &&
!haveComplained((u_long)syslogdname, (u_long)complaint))
{
ns_info(ns_log_default, "%s: query(%s) %s",
sysloginfo, syslogdname, complaint);
}
return(-1);
}
/* Update the refcounts before the sort. */
for (i = naddr; i < (u_int)n; i++) {
DRCNTINC(qp->q_addr[i].nsdata);
DRCNTINC(qp->q_addr[i].ns);
}
if (n > 1) {
qsort((char *)qp->q_addr, n, sizeof(struct qserv),
(int (*)(const void *, const void *))qcomp);
}
return (n - naddr);
}
/*
* qcomp - compare two NS addresses, and return a negative, zero, or
* positive value depending on whether the first NS address is
* "better than", "equally good as", or "inferior to" the second
* NS address.
*
* How "goodness" is defined (for the purposes of this routine):
* - If the estimated round trip times differ by an amount deemed significant
* then the one with the smaller estimate is preferred; else
* - If we can determine which one is topologically closer then the
* closer one is preferred; else
* - The one with the smaller estimated round trip time is preferred
* (zero is returned if the two estimates are identical).
*
* How "topological closeness" is defined (for the purposes of this routine):
* Ideally, named could consult some magic map of the Internet and
* determine the length of the path to an arbitrary destination. Sadly,
* no such magic map exists. However, named does have a little bit of
* topological information in the form of the sortlist (which includes
* the directly connected subnet(s), the directly connected net(s), and
* any additional nets that the administrator has added using the "sortlist"
* directive in the bootfile. Thus, if only one of the addresses matches
* something in the sortlist then it is considered to be topologically
* closer. If both match, but match different entries in the sortlist,
* then the one that matches the entry closer to the beginning of the
* sorlist is considered to be topologically closer. In all other cases,
* topological closeness is ignored because it's either indeterminate or
* equal.
*
* How times are compared:
* Both times are rounded to the closest multiple of the NOISE constant
* defined below and then compared. If the rounded values are equal
* then the difference in the times is deemed insignificant. Rounding
* is used instead of merely taking the absolute value of the difference
* because doing the latter would make the ordering defined by this
* routine be incomplete in the mathematical sense (e.g. A > B and
* B > C would not imply A > C). The mathematics are important in
* practice to avoid core dumps in qsort().
*
* XXX: this doesn't solve the European root nameserver problem very well.
* XXX: we should detect and mark as inferior nameservers that give bogus
* answers
*
* (this was originally vixie's stuff but almquist fixed fatal bugs in it
* and wrote the above documentation)
*/
/*
* RTT delta deemed to be significant, in milliseconds. With the current
* definition of RTTROUND it must be a power of 2.
*/
#define NOISE 128 /* milliseconds; 0.128 seconds */
#define sign(x) (((x) < 0) ? -1 : ((x) > 0) ? 1 : 0)
#define RTTROUND(rtt) (((rtt) + (NOISE >> 1)) & ~(NOISE - 1))
int
qcomp(struct qserv *qs1, struct qserv *qs2) {
int pos1, pos2, pdiff;
u_long rtt1, rtt2;
long tdiff;
if ((!qs1->nsdata) || (!qs2->nsdata))
return 0;
rtt1 = qs1->nsdata->d_nstime;
rtt2 = qs2->nsdata->d_nstime;
#ifdef DEBUG
if (debug >= 10) {
char a1[sizeof "255.255.255.255"],
a2[sizeof "255.255.255.255"];
strcpy(a1, inet_ntoa(qs1->ns_addr.sin_addr));
strcpy(a2, inet_ntoa(qs2->ns_addr.sin_addr));
ns_debug(ns_log_default, 10,
"qcomp(%s, %s) %lu (%lu) - %lu (%lu) = %lu",
a1, a2,
rtt1, RTTROUND(rtt1),
rtt2, RTTROUND(rtt2),
rtt1 - rtt2);
}
#endif
if (RTTROUND(rtt1) == RTTROUND(rtt2)) {
pos1 = distance_of_address(server_options->topology,
qs1->ns_addr.sin_addr);
pos2 = distance_of_address(server_options->topology,
qs2->ns_addr.sin_addr);
pdiff = pos1 - pos2;
ns_debug(ns_log_default, 10, "\tpos1=%d, pos2=%d", pos1, pos2);
if (pdiff)
return (pdiff);
}
tdiff = rtt1 - rtt2;
return (sign(tdiff));
}
#undef sign
#undef RTTROUND
/*
* Arrange that forwarded query (qp) is retried after t seconds.
* Query list will be sorted after z_time is updated.
*/
void
schedretry(struct qinfo *qp, time_t t) {
struct qinfo *qp1, *qp2;
ns_debug(ns_log_default, 4, "schedretry(%#x, %ld sec)", qp, (long)t);
if (qp->q_time)
ns_debug(ns_log_default, 4,
"WARNING: schedretry(%#lx, %ld) q_time already %ld",
(u_long)qp, (long)t, (long)qp->q_time);
gettime(&tt);
t += (u_long) tt.tv_sec;
qp->q_time = t;
if ((qp1 = retryqp) == NULL) {
retryqp = qp;
qp->q_next = NULL;
goto done;
}
if (t < qp1->q_time) {
qp->q_next = qp1;
retryqp = qp;
goto done;
}
while ((qp2 = qp1->q_next) != NULL && qp2->q_time < t)
qp1 = qp2;
qp1->q_next = qp;
qp->q_next = qp2;
done:
reset_retrytimer();
}
/*
* Unsched is called to remove a forwarded query entry.
*/
void
unsched(struct qinfo *qp) {
struct qinfo *np;
ns_debug(ns_log_default, 3, "unsched(%#lx, %d)",
(u_long)qp, ntohs(qp->q_id));
if (retryqp == qp) {
retryqp = qp->q_next;
} else {
for (np = retryqp; np->q_next != NULL; np = np->q_next) {
if (np->q_next != qp)
continue;
np->q_next = qp->q_next; /* dequeue */
break;
}
}
qp->q_next = NULL; /* sanity check */
qp->q_time = 0;
reset_retrytimer();
}
void
reset_retrytimer() {
static evTimerID id;
if (retry_timer_set) {
(void) evClearTimer(ev, id);
retry_timer_set = 0;
}
if (retryqp) {
evSetTimer(ev, retrytimer, NULL,
evConsTime(retryqp->q_time, 0),
evConsTime(0, 0), &id);
retry_timer_set = 1;
} else
memset(&id, 0, sizeof id);
}
void
retrytimer(evContext ctx, void *uap, struct timespec due,
struct timespec ival) {
retry_timer_set = 0;
retry(retryqp);
}
/*
* Retry is called to retransmit query 'qp'.
*/
void
retry(struct qinfo *qp) {
int n;
HEADER *hp;
struct sockaddr_in *nsa;
ns_debug(ns_log_default, 3, "retry(%#lx) id=%d", (u_long)qp,
ntohs(qp->q_id));
if (qp->q_msg == NULL) { /* XXX - why? */
qremove(qp);
return;
}
if (qp->q_expire < tt.tv_sec) {
ns_debug(ns_log_default, 1,
"retry(%#lx): expired @ %lu (%d secs before now (%lu))",
(u_long)qp, (u_long)qp->q_expire,
(int)(tt.tv_sec - qp->q_expire),
(u_long)tt.tv_sec);
if (qp->q_stream || (qp->q_flags & Q_PRIMING))
goto fail;
qremove(qp);
return;
}
/* try next address */
n = qp->q_curaddr;
if (qp->q_fwd != NULL) {
qp->q_fwd = qp->q_fwd->next;
if (qp->q_fwd != NULL)
goto found;
/* Out of forwarders, try direct queries. */
}
if (qp->q_naddr > 0) {
++qp->q_addr[n].nretry;
if (!NS_OPTION_P(OPTION_FORWARD_ONLY)) {
do {
if (++n >= (int)qp->q_naddr)
n = 0;
if (qp->q_addr[n].nretry < MAXRETRY)
goto found;
} while (n != qp->q_curaddr);
}
}
fail:
/*
* Give up. Can't reach destination.
*/
hp = (HEADER *)(qp->q_cmsg ? qp->q_cmsg : qp->q_msg);
if (qp->q_flags & Q_PRIMING) {
/* Can't give up priming */
if (qp->q_expire < tt.tv_sec) {
/*
* The query has expired. Reset it and retry from
* the beginning.
*/
hp->rcode = NOERROR;
hp->qr = hp->aa = 0;
qp->q_fwd = server_options->fwdtab;
for (n = 0; n < (int)qp->q_naddr; n++)
qp->q_addr[n].nretry = 0;
n = 0;
qp->q_expire = tt.tv_sec + RETRY_TIMEOUT*2;
goto found;
}
/*
* The query hasn't expired yet; it probably ran out
* of servers or forwarders. Wait up to 60 seconds
* past the expire time.
*/
unsched(qp);
schedretry(qp, (time_t)(qp->q_expire - tt.tv_sec + 60));
return;
}
ns_debug(ns_log_default, 5, "give up");
n = ((HEADER *)qp->q_cmsg ? qp->q_cmsglen : qp->q_msglen);
hp->id = qp->q_id;
hp->qr = 1;
hp->ra = (NS_OPTION_P(OPTION_NORECURSE) == 0);
hp->rd = 1;
hp->rcode = SERVFAIL;
#ifdef DEBUG
if (debug >= 10)
fp_nquery(qp->q_msg, n, log_get_stream(packet_channel));
#endif
if (send_msg((u_char *)hp, n, qp)) {
ns_debug(ns_log_default, 1,
"gave up retry(%#lx) nsid=%d id=%d",
(u_long)qp, ntohs(qp->q_nsid), ntohs(qp->q_id));
}
if (NS_OPTION_P(OPTION_HOSTSTATS))
nameserIncr(qp->q_from.sin_addr, nssSentFail);
qremove(qp);
return;
found:
if (qp->q_fwd == 0 && qp->q_addr[n].nretry == 0)
qp->q_addr[n].stime = tt;
qp->q_curaddr = n;
hp = (HEADER *)qp->q_msg;
hp->rd = (qp->q_fwd ? 1 : 0);
nsa = Q_NEXTADDR(qp, n);
ns_debug(ns_log_default, 1,
"%s(addr=%d n=%d) -> [%s].%d ds=%d nsid=%d id=%d %dms",
(qp->q_fwd ? "reforw" : "resend"),
n, qp->q_addr[n].nretry,
inet_ntoa(nsa->sin_addr),
ntohs(nsa->sin_port), ds,
ntohs(qp->q_nsid), ntohs(qp->q_id),
(qp->q_addr[n].nsdata != 0)
? qp->q_addr[n].nsdata->d_nstime
: (-1));
#ifdef DEBUG
if (debug >= 10)
fp_nquery(qp->q_msg, qp->q_msglen,
log_get_stream(packet_channel));
#endif
if (qp->q_flags & Q_USEVC) {
if (tcp_send(qp) != NOERROR)
ns_debug(ns_log_default, 3,
"error resending tcp msg: %s",
strerror(errno));
} else if (sendto(ds, (char*)qp->q_msg, qp->q_msglen, 0,
(struct sockaddr *)nsa,
sizeof(struct sockaddr_in)) < 0)
{
ns_debug(ns_log_default, 3, "error resending msg: %s",
strerror(errno));
}
hp->rd = 1; /* leave set to 1 for dup detection */
nameserIncr(nsa->sin_addr, nssSentDupQ);
unsched(qp);
#ifdef SLAVE_FORWARD
if (NS_OPTION_P(OPTION_FORWARD_ONLY))
schedretry(qp, (time_t)slave_retry);
else
#endif /* SLAVE_FORWARD */
schedretry(qp, qp->q_fwd ? (2*RETRYBASE) : retrytime(qp));
}
/*
* Compute retry time for the next server for a query.
* Use a minimum time of RETRYBASE (4 sec.) or twice the estimated
* service time; * back off exponentially on retries, but place a 45-sec.
* ceiling on retry times for now. (This is because we don't hold a reference
* on servers or their addresses, and we have to finish before they time out.)
*/
time_t
retrytime(struct qinfo *qp) {
time_t t, u, v;
struct qserv *ns = &qp->q_addr[qp->q_curaddr];
if (ns->nsdata != NULL)
t = (time_t) MAX(RETRYBASE, 2 * ns->nsdata->d_nstime / 1000);
else
t = (time_t) RETRYBASE;
u = t << ns->nretry;
v = MIN(u, RETRY_TIMEOUT); /* max. retry timeout for now */
ns_debug(ns_log_default, 3,
"retrytime: nstime%ldms t%ld nretry%ld u%ld : v%ld",
ns->nsdata ? (long)(ns->nsdata->d_nstime / 1000) : (long)-1,
(long)t, (long)ns->nretry, (long)u, (long)v);
return (v);
}
void
qflush() {
while (nsqhead)
qremove(nsqhead);
nsqhead = NULL;
priming = 0;
}
void
qremove(struct qinfo *qp) {
struct sockaddr_in empty_from;
empty_from.sin_family = AF_INET;
empty_from.sin_addr.s_addr = htonl(INADDR_ANY);
empty_from.sin_port = htons(0);
ns_debug(ns_log_default, 3, "qremove(%#lx)", (u_long)qp);
if (qp->q_flags & Q_ZSERIAL)
qserial_answer(qp, 0, empty_from);
unsched(qp);
ns_freeqry(qp);
}
struct qinfo *
qfindid(u_int16_t id) {
struct qinfo *qp;
for (qp = nsqhead; qp != NULL; qp = qp->q_link)
if (qp->q_nsid == id)
break;
ns_debug(ns_log_default, 3, "qfindid(%d) -> %#lx", ntohs(id),
(u_long)qp);
return (qp);
}
struct qinfo *
qnew(const char *name, int class, int type) {
struct qinfo *qp;
qp = (struct qinfo *)memget(sizeof *qp);
if (qp == NULL)
panic("qnew: memget failed", NULL);
memset(qp, 0, sizeof *qp);
ns_debug(ns_log_default, 5, "qnew(%#lx)", (u_long)qp);
#ifdef BIND_NOTIFY
qp->q_notifyzone = DB_Z_CACHE;
#endif
qp->q_link = nsqhead;
nsqhead = qp;
qp->q_name = savestr(name, 1);
qp->q_class = (u_int16_t)class;
qp->q_type = (u_int16_t)type;
qp->q_flags = 0;
return (qp);
}
void
ns_freeqns(struct qinfo *qp, char *where) {
static const char freed[] = "freed", busy[] = "busy";
const char *result;
struct databuf *dp;
int i;
for (i = 0 ; i < (int)qp->q_naddr ; i++) {
dp = qp->q_addr[i].ns;
if (dp) {
DRCNTDEC(dp);
result = (dp->d_rcnt) ? busy : freed;
ns_debug(ns_log_default, 3, "%s: ns %s rcnt %d (%s)",
where, dp->d_data, dp->d_rcnt, result);
if (result == freed)
db_freedata(dp);
}
dp = qp->q_addr[i].nsdata;
if (dp) {
DRCNTDEC(dp);
result = (dp->d_rcnt) ? busy : freed;
ns_debug(ns_log_default, 3,
"%s: nsdata %s rcnt %d (%s)",
where, inet_ntoa(ina_get(dp->d_data)),
dp->d_rcnt, result);
if (result == freed)
db_freedata(dp);
}
}
}
void
ns_freeqry(struct qinfo *qp) {
struct qinfo *np;
struct databuf *dp;
ns_debug(ns_log_default, 3, "ns_freeqry(%#lx)", (u_long)qp);
if (qp->q_next)
ns_debug(ns_log_default, 1,
"WARNING: ns_freeqry of linked ptr %#lx", (u_long)qp);
if (qp->q_msg != NULL)
memput(qp->q_msg, qp->q_msgsize);
if (qp->q_cmsg != NULL)
memput(qp->q_cmsg, qp->q_cmsgsize);
if (qp->q_domain != NULL)
freestr(qp->q_domain);
if (qp->q_name != NULL)
freestr(qp->q_name);
ns_freeqns(qp, "ns_freeqry");
if (nsqhead == qp)
nsqhead = qp->q_link;
else {
for(np = nsqhead;
np->q_link != NULL;
np = np->q_link) {
if (np->q_link != qp)
continue;
np->q_link = qp->q_link; /* dequeue */
break;
}
}
memput(qp, sizeof *qp);
}
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