4.3BSD-Reno/src/usr.sbin/named/ns_forw.c
/*-
* Copyright (c) 1986 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted provided
* that: (1) source distributions retain this entire copyright notice and
* comment, and (2) distributions including binaries display the following
* acknowledgement: ``This product includes software developed by the
* University of California, Berkeley and its contributors'' in the
* documentation or other materials provided with the distribution and in
* all advertising materials mentioning features or use of this software.
* 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
#ifndef lint
static char sccsid[] = "@(#)ns_forw.c 4.30 (Berkeley) 6/27/90";
#endif /* not lint */
#include <sys/param.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <syslog.h>
#include <arpa/nameser.h>
#include <stdio.h>
#include "ns.h"
#include "db.h"
struct qinfo *qhead = QINFO_NULL; /* head of allocated queries */
struct qinfo *retryqp = QINFO_NULL; /* list of queries to retry */
struct fwdinfo *fwdtab; /* list of forwarding hosts */
int nsid; /* next forwarded query id */
extern int forward_only; /* you are only a slave */
extern int errno;
extern u_short ns_port;
time_t retrytime();
/*
* 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 malloc error.
* (no action is taken on errors and qpp is not filled in.)
*/
ns_forw(nsp, msg, msglen, fp, qsp, dfd, qpp)
struct databuf *nsp[];
char *msg;
int msglen;
struct sockaddr_in *fp;
struct qstream *qsp;
int dfd;
struct qinfo **qpp;
{
register struct qinfo *qp;
HEADER *hp;
u_short id;
extern char *calloc();
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"ns_forw()\n");
#endif
/* Don't forward if we're already working on it. */
hp = (HEADER *) msg;
id = hp->id;
/* Look at them all */
for (qp = qhead; qp!=QINFO_NULL; qp = qp->q_link) {
if (qp->q_id == id &&
bcmp((char *)&qp->q_from, fp, sizeof(qp->q_from)) == 0 &&
((qp->q_cmsglen == 0 && qp->q_msglen == msglen &&
bcmp((char *)qp->q_msg+2, msg+2, msglen-2) == 0) ||
(qp->q_cmsglen == msglen &&
bcmp((char *)qp->q_cmsg+2, msg+2, msglen-2) == 0))) {
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"forw: dropped DUP id=%d\n", ntohs(id));
#endif
#ifdef STATS
stats[S_DUPQUERIES].cnt++;
#endif
return (FW_DUP);
}
}
qp = qnew();
if (nslookup(nsp, qp) == 0) {
#ifdef DEBUG
if (debug >= 2)
fprintf(ddt,"forw: no nameservers found\n");
#endif
qfree(qp);
return (FW_NOSERVER);
}
qp->q_stream = qsp;
qp->q_curaddr = 0;
qp->q_fwd = fwdtab;
qp->q_dfd = dfd;
qp->q_id = id;
hp->id = qp->q_nsid = htons((u_short)++nsid);
hp->ancount = 0;
hp->nscount = 0;
hp->arcount = 0;
qp->q_from = *fp;
if ((qp->q_msg = malloc((unsigned)msglen)) == NULL) {
syslog(LOG_ERR, "forw: %m");
qfree(qp);
return (FW_SERVFAIL);
}
bcopy(msg, qp->q_msg, qp->q_msglen = msglen);
if (!qp->q_fwd) {
hp->rd = 0;
qp->q_addr[0].stime = tt;
}
schedretry(qp, retrytime(qp));
#ifdef DEBUG
if (debug)
fprintf(ddt,
"forw: forw -> %s %d (%d) nsid=%d id=%d %dms retry %d sec\n",
inet_ntoa(Q_NEXTADDR(qp,0)->sin_addr),
ds, ntohs(Q_NEXTADDR(qp,0)->sin_port),
ntohs(qp->q_nsid), ntohs(qp->q_id),
qp->q_addr[0].nsdata->d_nstime,
qp->q_time - tt.tv_sec);
if ( debug >= 10)
fp_query(msg, ddt);
#endif
if (sendto(ds, msg, msglen, 0, (struct sockaddr *)Q_NEXTADDR(qp,0),
sizeof(struct sockaddr_in)) < 0){
#ifdef DEBUG
if (debug >= 5)
fprintf(ddt,"error returning msg errno=%d\n",errno);
#endif
}
#ifdef STATS
stats[S_OUTPKTS].cnt++;
#endif
if (qpp)
*qpp = qp;
hp->rd = 1;
return (0);
}
/*
* Lookup the address for each nameserver in `nsp' and add it to
* the list saved in the qinfo structure.
*/
nslookup(nsp, qp)
struct databuf *nsp[];
register struct qinfo *qp;
{
register struct namebuf *np;
register struct databuf *dp, *nsdp;
register struct qserv *qs;
register int n, i;
struct hashbuf *tmphtp;
char *dname, *fname;
int oldn, naddr, class, found_arr;
time_t curtime;
int qcomp();
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"nslookup(nsp=x%x,qp=x%x)\n",nsp,qp);
#endif
naddr = n = qp->q_naddr;
curtime = (u_long) tt.tv_sec;
while ((nsdp = *nsp++) != NULL) {
class = nsdp->d_class;
dname = nsdp->d_data;
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"nslookup: NS %s c%d t%d (x%x)\n",
dname, class, nsdp->d_type, nsdp->d_flags);
#endif
/* don't put in people we have tried */
for (i = 0; i < qp->q_nusedns; i++)
if (qp->q_usedns[i] == nsdp) {
#ifdef DEBUG
if (debug >= 2)
fprintf(ddt, "skipping used NS w/name %s\n", nsdp->d_data);
#endif DEBUG
goto skipserver;
}
tmphtp = ((nsdp->d_flags & DB_F_HINT) ? fcachetab : hashtab);
np = nlookup(dname, &tmphtp, &fname, 1);
if (np == NULL || fname != dname) {
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"%s: not found %s %x\n",dname,fname,np);
#endif
continue;
}
found_arr = 0;
oldn = n;
/* look for name server addresses */
for (dp = np->n_data; dp != NULL; dp = dp->d_next) {
if (dp->d_type != T_A || dp->d_class != class)
continue;
/*
* 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 == 0) &&
(dp->d_ttl < (curtime+900)) &&
!(dp->d_flags & DB_F_HINT) )
{
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"nslookup: stale entry '%s'\n",
np->n_dname);
#endif
/* Cache invalidate the NS RR's */
if (dp->d_ttl < curtime)
delete_all(np, class, T_A);
n = oldn;
break;
}
found_arr++;
/* don't put in duplicates */
qs = qp->q_addr;
for (i = 0; i < n; i++, qs++)
if (bcmp((char *)&qs->ns_addr.sin_addr,
dp->d_data, sizeof(struct in_addr)) == 0)
goto skipaddr;
qs->ns_addr.sin_family = AF_INET;
qs->ns_addr.sin_port = ns_port;
qs->ns_addr.sin_addr =
*(struct in_addr *)dp->d_data;
qs->ns = nsdp;
qs->nsdata = dp;
qp->q_addr[n].nretry = 0;
n++;
if (n >= NSMAX)
goto out;
skipaddr: ;
}
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"nslookup: %d ns addrs\n", n);
#endif
if (found_arr == 0 && qp->q_system == 0)
(void) sysquery(dname, class, T_A);
skipserver: ;
}
out:
#ifdef DEBUG
if (debug >= 3)
fprintf(ddt,"nslookup: %d ns addrs total\n", n);
#endif
qp->q_naddr = n;
if (n > 1)
qsort((char *)qp->q_addr, n, sizeof(struct qserv), qcomp);
return (n - naddr);
}
qcomp(qs1, qs2)
struct qserv *qs1, *qs2;
{
return (qs1->nsdata->d_nstime - qs2->nsdata->d_nstime);
}
/*
* Arrange that forwarded query (qp) is retried after t seconds.
*/
schedretry(qp, t)
struct qinfo *qp;
time_t t;
{
register struct qinfo *qp1, *qp2;
#ifdef DEBUG
if (debug > 3) {
fprintf(ddt,"schedretry(%#x, %dsec)\n", qp, t);
if (qp->q_time)
fprintf(ddt,"WARNING: schedretry(%x,%d) q_time already %d\n", qp->q_time);
}
#endif
t += (u_long) tt.tv_sec;
qp->q_time = t;
if ((qp1 = retryqp) == NULL) {
retryqp = qp;
qp->q_next = NULL;
return;
}
if (t < qp1->q_time) {
qp->q_next = qp1;
retryqp = qp;
return;
}
while ((qp2 = qp1->q_next) != NULL && qp2->q_time < t)
qp1 = qp2;
qp1->q_next = qp;
qp->q_next = qp2;
}
/*
* Unsched is called to remove a forwarded query entry.
*/
unsched(qp)
struct qinfo *qp;
{
register struct qinfo *np;
#ifdef DEBUG
if (debug > 3) {
fprintf(ddt,"unsched(%#x, %d )\n", qp, ntohs(qp->q_id));
}
#endif
if( retryqp == qp ) {
retryqp = qp->q_next;
} else {
for( np=retryqp; np->q_next != QINFO_NULL; np = np->q_next ) {
if( np->q_next != qp)
continue;
np->q_next = qp->q_next; /* dequeue */
break;
}
}
qp->q_next = QINFO_NULL; /* sanity check */
qp->q_time = 0;
}
/*
* Retry is called to retransmit query 'qp'.
*/
retry(qp)
register struct qinfo *qp;
{
register int n;
register HEADER *hp;
#ifdef DEBUG
if (debug > 3)
fprintf(ddt,"retry(x%x) id=%d\n", qp, ntohs(qp->q_id));
#endif
if((HEADER *)qp->q_msg == NULL) { /*** XXX ***/
qremove(qp);
return;
} /*** XXX ***/
/* try next address */
n = qp->q_curaddr;
if (qp->q_fwd) {
qp->q_fwd = qp->q_fwd->next;
if (qp->q_fwd)
goto found;
/* out of forwarders, try direct queries */
} else
++qp->q_addr[n].nretry;
if (!forward_only) {
do {
if (++n >= qp->q_naddr)
n = 0;
if (qp->q_addr[n].nretry < MAXRETRY)
goto found;
} while (n != qp->q_curaddr);
}
/*
* Give up. Can't reach destination.
*/
hp = (HEADER *)(qp->q_cmsg ? qp->q_cmsg : qp->q_msg);
if (qp->q_system == PRIMING_CACHE) {
/* Can't give up priming */
unsched(qp);
schedretry(qp, (time_t)60*60); /* 1 hour */
hp->rcode = NOERROR; /* Lets be safe, reset the query */
hp->qr = hp->aa = 0;
qp->q_fwd = fwdtab;
for (n = 0; n < qp->q_naddr; n++)
qp->q_addr[n].nretry = 0;
return;
}
#ifdef DEBUG
if (debug >= 5)
fprintf(ddt,"give up\n");
#endif
n = ((HEADER *)qp->q_cmsg ? qp->q_cmsglen : qp->q_msglen);
hp->id = qp->q_id;
hp->qr = 1;
hp->ra = 1;
hp->rd = 1;
hp->rcode = SERVFAIL;
#ifdef DEBUG
if (debug >= 10)
fp_query(qp->q_msg, ddt);
#endif
if (send_msg((char *)hp, n, qp)) {
#ifdef DEBUG
if (debug)
fprintf(ddt,"gave up retry(x%x) nsid=%d id=%d\n",
qp, ntohs(qp->q_nsid), ntohs(qp->q_id));
#endif
}
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);
#ifdef DEBUG
if (debug)
fprintf(ddt,"%s(addr=%d n=%d) -> %s %d (%d) nsid=%d id=%d %dms\n",
(qp->q_fwd ? "reforw" : "resend"),
n, qp->q_addr[n].nretry,
inet_ntoa(Q_NEXTADDR(qp,n)->sin_addr),
ds, ntohs(Q_NEXTADDR(qp,n)->sin_port),
ntohs(qp->q_nsid), ntohs(qp->q_id),
qp->q_addr[n].nsdata->d_nstime);
if ( debug >= 10)
fp_query(qp->q_msg, ddt);
#endif
/* NOSTRICT */
if (sendto(ds, qp->q_msg, qp->q_msglen, 0,
(struct sockaddr *)Q_NEXTADDR(qp,n),
sizeof(struct sockaddr_in)) < 0){
#ifdef DEBUG
if (debug > 3)
fprintf(ddt,"error resending msg errno=%d\n",errno);
#endif
}
hp->rd = 1; /* leave set to 1 for dup detection */
#ifdef STATS
stats[S_OUTPKTS].cnt++;
#endif
unsched(qp);
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(qp)
register struct qinfo *qp;
{
time_t t;
struct qserv *ns = &qp->q_addr[qp->q_curaddr];
#ifdef DEBUG
if (debug > 3)
fprintf(ddt,"retrytime: nstime %dms.\n",
ns->nsdata->d_nstime / 1000);
#endif
t = (time_t) MAX(RETRYBASE, 2 * ns->nsdata->d_nstime / 1000);
t <<= ns->nretry;
t = MIN(t, 45); /* max. retry timeout for now */
#ifdef notdef
if (qp->q_system)
return ((2 * t) + 5); /* system queries can wait. */
#endif
return (t);
}
qflush()
{
while (qhead)
qremove(qhead);
qhead = QINFO_NULL;
}
qremove(qp)
register struct qinfo *qp;
{
#ifdef DEBUG
if(debug > 3)
fprintf(ddt,"qremove(x%x)\n", qp);
#endif
unsched(qp); /* get off queue first */
qfree(qp);
}
struct qinfo *
qfindid(id)
register u_short id;
{
register struct qinfo *qp;
#ifdef DEBUG
if(debug > 3)
fprintf(ddt,"qfindid(%d)\n", ntohs(id));
#endif
for (qp = qhead; qp!=QINFO_NULL; qp = qp->q_link) {
if (qp->q_nsid == id)
return(qp);
}
#ifdef DEBUG
if (debug >= 5)
fprintf(ddt,"qp not found\n");
#endif
return(NULL);
}
struct qinfo *
qnew()
{
register struct qinfo *qp;
if ((qp = (struct qinfo *)calloc(1, sizeof(struct qinfo))) == NULL) {
#ifdef DEBUG
if (debug >= 5)
fprintf(ddt,"qnew: calloc error\n");
#endif
syslog(LOG_ERR, "forw: %m");
exit(12);
}
#ifdef DEBUG
if (debug >= 5)
fprintf(ddt,"qnew(x%x)\n", qp);
#endif
qp->q_link = qhead;
qhead = qp;
return( qp );
}
qfree(qp)
struct qinfo *qp;
{
register struct qinfo *np;
#ifdef DEBUG
if(debug > 3)
fprintf(ddt,"qfree( x%x )\n", qp);
if(debug && qp->q_next)
fprintf(ddt,"WARNING: qfree of linked ptr x%x\n", qp);
#endif
if (qp->q_msg)
free(qp->q_msg);
if (qp->q_cmsg)
free(qp->q_cmsg);
if( qhead == qp ) {
qhead = qp->q_link;
} else {
for( np=qhead; np->q_link != QINFO_NULL; np = np->q_link ) {
if( np->q_link != qp ) continue;
np->q_link = qp->q_link; /* dequeue */
break;
}
}
(void)free((char *)qp);
}