FreeBSD-5.3/usr.sbin/ypserv/yp_dnslookup.c
/*
* Copyright (c) 1995, 1996
* Bill Paul <wpaul@ctr.columbia.edu>. 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 Bill Paul.
* 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 Bill Paul 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 Bill Paul 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/usr.sbin/ypserv/yp_dnslookup.c,v 1.24 2003/05/03 21:06:42 obrien Exp $");
/*
* Do standard and reverse DNS lookups using the resolver library.
* Take care of all the dirty work here so the main program only has to
* pass us a pointer to an array of characters.
*
* We have to use direct resolver calls here otherwise the YP server
* could end up looping by calling itself over and over again until
* it disappeared up its own belly button.
*/
#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/fcntl.h>
#include <sys/queue.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <resolv.h>
#include <unistd.h>
#include <rpcsvc/yp.h>
#include "yp_extern.h"
static char *
parse(struct hostent *hp)
{
static char result[MAXHOSTNAMELEN * 2];
int len,i;
struct in_addr addr;
if (hp == NULL)
return(NULL);
len = 16 + strlen(hp->h_name);
for (i = 0; hp->h_aliases[i]; i++)
len += strlen(hp->h_aliases[i]) + 1;
len++;
if (len > sizeof(result))
return(NULL);
bzero(result, sizeof(result));
bcopy(hp->h_addr, &addr, sizeof(struct in_addr));
snprintf(result, sizeof(result), "%s %s", inet_ntoa(addr), hp->h_name);
for (i = 0; hp->h_aliases[i]; i++) {
strcat(result, " ");
strcat(result, hp->h_aliases[i]);
}
return ((char *)&result);
}
#define MAXPACKET 1024
#define DEF_TTL 50
#define BY_DNS_ID 1
#define BY_RPC_XID 2
extern struct hostent *__dns_getanswer(char *, int, char *, int);
static TAILQ_HEAD(dns_qhead, circleq_dnsentry) qhead;
struct circleq_dnsentry {
SVCXPRT *xprt;
unsigned long xid;
struct sockaddr_in client_addr;
unsigned long ypvers;
unsigned long id;
unsigned long ttl;
unsigned long type;
unsigned short prot_type;
char **domain;
char *name;
struct in_addr addr;
TAILQ_ENTRY(circleq_dnsentry) links;
};
static int pending = 0;
int
yp_init_resolver(void)
{
TAILQ_INIT(&qhead);
if (!(_res.options & RES_INIT) && res_init() == -1) {
yp_error("res_init failed");
return(1);
}
if ((resfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
yp_error("couldn't create socket");
return(1);
}
if (fcntl(resfd, F_SETFL, O_NONBLOCK) == -1) {
yp_error("couldn't make resolver socket non-blocking");
return(1);
}
return(0);
}
static struct
circleq_dnsentry *yp_malloc_dnsent(void)
{
register struct circleq_dnsentry *q;
q = (struct circleq_dnsentry *)malloc(sizeof(struct circleq_dnsentry));
if (q == NULL) {
yp_error("failed to malloc() circleq dns entry");
return(NULL);
}
return(q);
}
/*
* Transmit a query.
*/
static unsigned long
yp_send_dns_query(char *name, int type)
{
char buf[MAXPACKET];
int n;
HEADER *hptr;
int ns;
int rval;
unsigned long id;
bzero(buf, sizeof(buf));
n = res_mkquery(QUERY,name,C_IN,type,NULL,0,NULL,buf,sizeof(buf));
if (n <= 0) {
yp_error("res_mkquery failed for %s type %d", name, type);
return(0);
}
hptr = (HEADER *)&buf;
id = ntohs(hptr->id);
for (ns = 0; ns < _res.nscount; ns++) {
rval = sendto(resfd, buf, n, 0,
(struct sockaddr *)&_res.nsaddr_list[ns],
sizeof(struct sockaddr));
if (rval == -1) {
yp_error("sendto failed");
return(0);
}
}
return(id);
}
static struct circleq_dnsentry *
yp_find_dnsqent(unsigned long id, int type)
{
register struct circleq_dnsentry *q;
TAILQ_FOREACH(q, &qhead, links) {
switch (type) {
case BY_RPC_XID:
if (id == q->xid)
return(q);
break;
case BY_DNS_ID:
default:
if (id == q->id)
return(q);
break;
}
}
return (NULL);
}
static void
yp_send_dns_reply(struct circleq_dnsentry *q, char *buf)
{
ypresponse result_v1;
ypresp_val result_v2;
unsigned long xid;
struct sockaddr_in client_addr;
xdrproc_t xdrfunc;
char *result;
/*
* Set up correct reply struct and
* XDR filter depending on ypvers.
*/
switch (q->ypvers) {
case YPVERS:
bzero((char *)&result_v2, sizeof(result_v2));
if (buf == NULL)
result_v2.stat = YP_NOKEY;
else {
result_v2.val.valdat_len = strlen(buf);
result_v2.val.valdat_val = buf;
result_v2.stat = YP_TRUE;
}
result = (char *)&result_v2;
xdrfunc = (xdrproc_t)xdr_ypresp_val;
break;
case YPOLDVERS:
/*
* The odds are we will _never_ execute this
* particular code, but we include it anyway
* for the sake of completeness.
*/
bzero((char *)&result_v1, sizeof(result_v1));
result_v1.yp_resptype = YPRESP_VAL;
#define YPVAL ypresponse_u.yp_resp_valtype
if (buf == NULL)
result_v1.YPVAL.stat = YP_NOKEY;
else {
result_v1.YPVAL.val.valdat_len = strlen(buf);
result_v1.YPVAL.val.valdat_val = buf;
result_v1.YPVAL.stat = YP_TRUE;
}
result = (char *)&result_v1;
xdrfunc = (xdrproc_t)xdr_ypresponse;
break;
default:
yp_error("bad YP program version (%lu)!", q->ypvers);
return;
break;
}
if (debug)
yp_error("sending dns reply to %s (%lu)",
inet_ntoa(q->client_addr.sin_addr), q->id);
/*
* XXX This is disgusting. There's basically one transport
* handle for UDP, but we're holding off on replying to a
* client until we're ready, by which time we may have received
* several other queries from other clients with different
* transaction IDs. So to make the delayed response thing work,
* we have to save the transaction ID and client address of
* each request, then jam them into the transport handle when
* we're ready to send a reply. Then after we've send the reply,
* we put the old transaction ID and remote address back the
* way we found 'em. This is _INCREDIBLY_ non-portable; it's
* not even supported by the RPC library.
*/
/*
* XXX Don't frob the transaction ID for TCP handles.
*/
if (q->prot_type == SOCK_DGRAM)
xid = svcudp_set_xid(q->xprt, q->xid);
client_addr = q->xprt->xp_raddr;
q->xprt->xp_raddr = q->client_addr;
if (!svc_sendreply(q->xprt, xdrfunc, result))
yp_error("svc_sendreply failed");
/*
* Now that we sent the reply,
* put the handle back the way it was.
*/
if (q->prot_type == SOCK_DGRAM)
svcudp_set_xid(q->xprt, xid);
q->xprt->xp_raddr = client_addr;
return;
}
/*
* Decrement TTL on all queue entries, possibly nuking
* any that have been around too long without being serviced.
*/
void
yp_prune_dnsq(void)
{
register struct circleq_dnsentry *q, *n;
q = TAILQ_FIRST(&qhead);
while (q != NULL) {
q->ttl--;
n = TAILQ_NEXT(q, links);
if (!q->ttl) {
TAILQ_REMOVE(&qhead, q, links);
free(q->name);
free(q);
pending--;
}
q = n;
}
if (pending < 0)
pending = 0;
return;
}
/*
* Data is pending on the DNS socket; check for valid replies
* to our queries and dispatch them to waiting clients.
*/
void
yp_run_dnsq(void)
{
register struct circleq_dnsentry *q;
char buf[sizeof(HEADER) + MAXPACKET];
char retrybuf[MAXHOSTNAMELEN];
struct sockaddr_in sin;
int rval;
int len;
HEADER *hptr;
struct hostent *hent;
if (debug)
yp_error("running dns queue");
bzero(buf, sizeof(buf));
len = sizeof(struct sockaddr_in);
rval = recvfrom(resfd, buf, sizeof(buf), 0,
(struct sockaddr *)&sin, &len);
if (rval == -1) {
yp_error("recvfrom failed: %s", strerror(errno));
return;
}
/*
* We may have data left in the socket that represents
* replies to earlier queries that we don't care about
* anymore. If there are no lookups pending or the packet
* ID doesn't match any of the queue IDs, just drop it
* on the floor.
*/
hptr = (HEADER *)&buf;
if (!pending ||
(q = yp_find_dnsqent(ntohs(hptr->id), BY_DNS_ID)) == NULL) {
/* ignore */
return;
}
if (debug)
yp_error("got dns reply from %s", inet_ntoa(sin.sin_addr));
hent = __dns_getanswer(buf, rval, q->name, q->type);
if (hent != NULL) {
if (q->type == T_PTR) {
hent->h_addr = (char *)&q->addr.s_addr;
hent->h_length = sizeof(struct in_addr);
}
}
/* Got an answer ready for a client -- send it off. */
yp_send_dns_reply(q, parse(hent));
pending--;
TAILQ_REMOVE(&qhead, q, links);
free(q->name);
free(q);
/* Decrement TTLs on other entries while we're here. */
yp_prune_dnsq();
return;
}
/*
* Queue and transmit an asynchronous DNS hostname lookup.
*/
ypstat
yp_async_lookup_name(struct svc_req *rqstp, char *name)
{
register struct circleq_dnsentry *q;
int type, len;
/* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */
type = -1; len = sizeof(type);
if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET,
SO_TYPE, &type, &len) == -1) {
yp_error("getsockopt failed: %s", strerror(errno));
return(YP_YPERR);
}
/* Avoid transmitting dupe requests. */
if (type == SOCK_DGRAM &&
yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL)
return(YP_TRUE);
if ((q = yp_malloc_dnsent()) == NULL)
return(YP_YPERR);
q->type = T_A;
q->ttl = DEF_TTL;
q->xprt = rqstp->rq_xprt;
q->ypvers = rqstp->rq_vers;
q->prot_type = type;
if (q->prot_type == SOCK_DGRAM)
q->xid = svcudp_get_xid(q->xprt);
q->client_addr = q->xprt->xp_raddr;
q->domain = _res.dnsrch;
q->id = yp_send_dns_query(name, q->type);
if (q->id == 0) {
yp_error("DNS query failed");
free(q);
return(YP_YPERR);
}
q->name = strdup(name);
TAILQ_INSERT_HEAD(&qhead, q, links);
pending++;
if (debug)
yp_error("queueing async DNS name lookup (%d)", q->id);
yp_prune_dnsq();
return(YP_TRUE);
}
/*
* Queue and transmit an asynchronous DNS IP address lookup.
*/
ypstat
yp_async_lookup_addr(struct svc_req *rqstp, char *addr)
{
register struct circleq_dnsentry *q;
char buf[MAXHOSTNAMELEN];
int a, b, c, d;
int type, len;
/* Check for SOCK_DGRAM or SOCK_STREAM -- we need to know later */
type = -1; len = sizeof(type);
if (getsockopt(rqstp->rq_xprt->xp_fd, SOL_SOCKET,
SO_TYPE, &type, &len) == -1) {
yp_error("getsockopt failed: %s", strerror(errno));
return(YP_YPERR);
}
/* Avoid transmitting dupe requests. */
if (type == SOCK_DGRAM &&
yp_find_dnsqent(svcudp_get_xid(rqstp->rq_xprt),BY_RPC_XID) != NULL)
return(YP_TRUE);
if ((q = yp_malloc_dnsent()) == NULL)
return(YP_YPERR);
if (sscanf(addr, "%d.%d.%d.%d", &a, &b, &c, &d) != 4)
return(YP_NOKEY);
snprintf(buf, sizeof(buf), "%d.%d.%d.%d.in-addr.arpa", d, c, b, a);
if (debug)
yp_error("DNS address is: %s", buf);
q->type = T_PTR;
q->ttl = DEF_TTL;
q->xprt = rqstp->rq_xprt;
q->ypvers = rqstp->rq_vers;
q->domain = NULL;
q->prot_type = type;
if (q->prot_type == SOCK_DGRAM)
q->xid = svcudp_get_xid(q->xprt);
q->client_addr = q->xprt->xp_raddr;
q->id = yp_send_dns_query(buf, q->type);
if (q->id == 0) {
yp_error("DNS query failed");
free(q);
return(YP_YPERR);
}
inet_aton(addr, &q->addr);
q->name = strdup(buf);
TAILQ_INSERT_HEAD(&qhead, q, links);
pending++;
if (debug)
yp_error("queueing async DNS address lookup (%d)", q->id);
yp_prune_dnsq();
return(YP_TRUE);
}