xref: /src/usr.sbin/ypbind/ypbind.c

/*
 * Copyright (c) 1992, 1993 Theo de Raadt <deraadt (at) fsa.ca>
 * 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 Theo de Raadt.
 * 4. The name of the author may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#ifndef LINT
static char rcsid[] = "$Id: ypbind.c,v 1.18 1995/01/15 09:09:30 mycroft Exp $";
#endif

#include <sys/param.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <sys/uio.h>
#include <sys/syslog.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include <dirent.h>
#include <netdb.h>
#include <string.h>
#include <rpc/rpc.h>
#include <rpc/xdr.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <rpc/pmap_clnt.h>
#include <rpc/pmap_prot.h>
#include <rpc/pmap_rmt.h>
#include <unistd.h>
#include <rpcsvc/yp_prot.h>
#include <rpcsvc/ypclnt.h>

#define BINDINGDIR	"/var/yp/binding"
#define YPBINDLOCK	"/var/run/ypbind.lock"

struct _dom_binding {
	struct _dom_binding *dom_pnext;
	char dom_domain[YPMAXDOMAIN + 1];
	struct sockaddr_in dom_server_addr;
	unsigned short int dom_server_port;
	int dom_socket;
	CLIENT *dom_client;
	long int dom_vers;
	time_t dom_check_t;
	time_t dom_ask_t;
	int dom_lockfd;
	int dom_alive;
};

extern bool_t xdr_domainname(), xdr_ypbind_resp();
extern bool_t xdr_ypreq_key(), xdr_ypresp_val();
extern bool_t xdr_ypbind_setdom();

char *domainname;

struct _dom_binding *ypbindlist;
int check;

#define YPSET_NO	0
#define YPSET_LOCAL	1
#define YPSET_ALL	2
int ypsetmode = YPSET_NO;

int rpcsock, pingsock;
struct rmtcallargs rmtca;
struct rmtcallres rmtcr;
char rmtcr_outval;
u_long rmtcr_port;
SVCXPRT *udptransp, *tcptransp;

void *
ypbindproc_null_2(transp, argp, clnt)
	SVCXPRT *transp;
	void *argp;
	CLIENT *clnt;
{
	static char res;

	memset(&res, 0, sizeof(res));
	return (void *)&res;
}

struct ypbind_resp *
ypbindproc_domain_2(transp, argp, clnt)
	SVCXPRT *transp;
	char *argp;
	CLIENT *clnt;
{
	static struct ypbind_resp res;
	struct _dom_binding *ypdb;
	char path[MAXPATHLEN];
	time_t now;

	memset(&res, 0, sizeof res);
	res.ypbind_status = YPBIND_FAIL_VAL;

	for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext)
		if (!strcmp(ypdb->dom_domain, argp))
			break;

	if (ypdb == NULL) {
		ypdb = (struct _dom_binding *)malloc(sizeof *ypdb);
		memset(ypdb, 0, sizeof *ypdb);
		strncpy(ypdb->dom_domain, argp, sizeof ypdb->dom_domain);
		ypdb->dom_vers = YPVERS;
		ypdb->dom_alive = 0;
		ypdb->dom_lockfd = -1;
		sprintf(path, "%s/%s.%d", BINDINGDIR, ypdb->dom_domain, ypdb->dom_vers);
		unlink(path);
		ypdb->dom_pnext = ypbindlist;
		ypbindlist = ypdb;
		check++;
		return NULL;
	}

	if (ypdb->dom_alive == 0)
		return NULL;

#ifdef HEURISTIC
	time(&now);
	if (now < ypdb->dom_ask_t + 5) {
		/*
		 * Hmm. More than 2 requests in 5 seconds have indicated
		 * that my binding is possibly incorrect.
		 * Ok, do an immediate poll of the server.
		 */
		if (ypdb->dom_check_t >= now) {
			/* don't flood it */
			ypdb->dom_check_t = 0;
			check++;
		}
	}
	ypdb->dom_ask_t = now;
#endif

answer:
	res.ypbind_status = YPBIND_SUCC_VAL;
	res.ypbind_respbody.ypbind_bindinfo.ypbind_binding_addr.s_addr =
		ypdb->dom_server_addr.sin_addr.s_addr;
	res.ypbind_respbody.ypbind_bindinfo.ypbind_binding_port =
		ypdb->dom_server_port;
	/*printf("domain %s at %s/%d\n", ypdb->dom_domain,
		inet_ntoa(ypdb->dom_server_addr.sin_addr),
		ntohs(ypdb->dom_server_addr.sin_port));*/
	return &res;
}

bool_t *
ypbindproc_setdom_2(transp, argp, clnt)
	SVCXPRT *transp;
	struct ypbind_setdom *argp;
	CLIENT *clnt;
{
	struct sockaddr_in *fromsin, bindsin;
	static bool_t res;

	memset(&res, 0, sizeof(res));
	fromsin = svc_getcaller(transp);

	switch (ypsetmode) {
	case YPSET_LOCAL:
		if (fromsin->sin_addr.s_addr != htonl(INADDR_LOOPBACK))
			return (bool_t *)NULL;
		break;
	case YPSET_ALL:
		break;
	case YPSET_NO:
	default:
		return (bool_t *)NULL;
	}

	if (ntohs(fromsin->sin_port) >= IPPORT_RESERVED)
		return &res;

	if (argp->ypsetdom_vers != YPVERS)
		return &res;

	memset(&bindsin, 0, sizeof bindsin);
	bindsin.sin_family = AF_INET;
	bindsin.sin_len = sizeof(bindsin);
	bindsin.sin_addr = argp->ypsetdom_addr;
	bindsin.sin_port = argp->ypsetdom_port;
	rpc_received(argp->ypsetdom_domain, &bindsin, 1);

	res = 1;
	return &res;
}

static void
ypbindprog_2(rqstp, transp)
	struct svc_req *rqstp;
	register SVCXPRT *transp;
{
	union {
		char ypbindproc_domain_2_arg[MAXHOSTNAMELEN];
		struct ypbind_setdom ypbindproc_setdom_2_arg;
	} argument;
	struct authunix_parms *creds;
	char *result;
	bool_t (*xdr_argument)(), (*xdr_result)();
	char *(*local)();

	switch (rqstp->rq_proc) {
	case YPBINDPROC_NULL:
		xdr_argument = xdr_void;
		xdr_result = xdr_void;
		local = (char *(*)()) ypbindproc_null_2;
		break;

	case YPBINDPROC_DOMAIN:
		xdr_argument = xdr_domainname;
		xdr_result = xdr_ypbind_resp;
		local = (char *(*)()) ypbindproc_domain_2;
		break;

	case YPBINDPROC_SETDOM:
		switch (rqstp->rq_cred.oa_flavor) {
		case AUTH_UNIX:
			creds = (struct authunix_parms *)rqstp->rq_clntcred;
			if (creds->aup_uid != 0) {
				svcerr_auth(transp, AUTH_BADCRED);
				return;
			}
			break;
		default:
			svcerr_auth(transp, AUTH_TOOWEAK);
			return;
		}

		xdr_argument = xdr_ypbind_setdom;
		xdr_result = xdr_void;
		local = (char *(*)()) ypbindproc_setdom_2;
		break;

	default:
		svcerr_noproc(transp);
		return;
	}
	memset(&argument, 0, sizeof(argument));
	if (!svc_getargs(transp, xdr_argument, (caddr_t)&argument)) {
		svcerr_decode(transp);
		return;
	}
	result = (*local)(transp, &argument, rqstp);
	if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
		svcerr_systemerr(transp);
	}
	return;
}

main(argc, argv)
	int argc;
	char *argv[];
{
	char path[MAXPATHLEN];
	struct timeval tv;
	fd_set fdsr;
	int width, lockfd;
	int evil = 0, one;

	yp_get_default_domain(&domainname);
	if (domainname[0] == '\0') {
		fprintf(stderr, "domainname not set. Aborting.\n");
		exit(1);
	}

	while (--argc) {
		++argv;
		if (!strcmp("-ypset", *argv))
			ypsetmode = YPSET_ALL;
		else if (!strcmp("-ypsetme", *argv))
			ypsetmode = YPSET_LOCAL;
	}

	/* blow away everything in BINDINGDIR */

#ifdef O_SHLOCK
	if ((lockfd = open(YPBINDLOCK, O_CREAT|O_SHLOCK|O_RDWR|O_TRUNC, 0644)) == -1) {
		fprintf(stderr, "ypbind: cannot create %s\n", YPBINDLOCK);
		exit(1);
	}
#else
	if ((lockfd = open(YPBINDLOCK, O_CREAT|O_RDWR|O_TRUNC, 0644)) == -1) {
		fprintf(stderr, "ypbind: cannot create %s\n", YPBINDLOCK);
		exit(1);
	}
	flock(lockfd, LOCK_SH);
#endif

	(void)pmap_unset(YPBINDPROG, YPBINDVERS);

	udptransp = svcudp_create(RPC_ANYSOCK);
	if (udptransp == NULL) {
		fprintf(stderr, "cannot create udp service.");
		exit(1);
	}
	if (!svc_register(udptransp, YPBINDPROG, YPBINDVERS, ypbindprog_2,
	    IPPROTO_UDP)) {
		fprintf(stderr, "unable to register (YPBINDPROG, YPBINDVERS, udp).");
		exit(1);
	}

	tcptransp = svctcp_create(RPC_ANYSOCK, 0, 0);
	if (tcptransp == NULL) {
		fprintf(stderr, "cannot create tcp service.");
		exit(1);
	}
	if (!svc_register(tcptransp, YPBINDPROG, YPBINDVERS, ypbindprog_2,
	    IPPROTO_TCP)) {
		fprintf(stderr, "unable to register (YPBINDPROG, YPBINDVERS, tcp).");
		exit(1);
	}

	if ((rpcsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
		perror("socket");
		return -1;
	}
	if ((pingsock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
		perror("socket");
		return -1;
	}

	fcntl(rpcsock, F_SETFL, fcntl(rpcsock, F_GETFL, 0) | FNDELAY);
	fcntl(pingsock, F_SETFL, fcntl(rpcsock, F_GETFL, 0) | FNDELAY);
	one = 1;
	setsockopt(rpcsock, SOL_SOCKET, SO_BROADCAST, &one, sizeof(one));
	rmtca.prog = YPPROG;
	rmtca.vers = YPVERS;
	rmtca.proc = YPPROC_DOMAIN_NONACK;
	rmtca.xdr_args = NULL;		/* set at call time */
	rmtca.args_ptr = NULL;		/* set at call time */
	rmtcr.port_ptr = &rmtcr_port;
	rmtcr.xdr_results = xdr_bool;
	rmtcr.results_ptr = (caddr_t)&rmtcr_outval;

	/* build initial domain binding, make it "unsuccessful" */
	ypbindlist = (struct _dom_binding *)malloc(sizeof *ypbindlist);
	memset(ypbindlist, 0, sizeof *ypbindlist);
	strncpy(ypbindlist->dom_domain, domainname, sizeof ypbindlist->dom_domain);
	ypbindlist->dom_vers = YPVERS;
	ypbindlist->dom_alive = 0;
	ypbindlist->dom_lockfd = -1;
	sprintf(path, "%s/%s.%d", BINDINGDIR, ypbindlist->dom_domain,
		ypbindlist->dom_vers);
	(void)unlink(path);

	checkwork();

	while (1) {
		width = svc_maxfd;
		if (rpcsock > width)
			width = rpcsock;
		if (pingsock > width)
			width = pingsock;
		width++;

		fdsr = svc_fdset;
		FD_SET(rpcsock, &fdsr);
		FD_SET(pingsock, &fdsr);
		tv.tv_sec = 1;
		tv.tv_usec = 0;

		switch (select(width, &fdsr, NULL, NULL, &tv)) {
		case 0:
			checkwork();
			break;
		case -1:
			perror("select\n");
			break;
		default:
			if (FD_ISSET(rpcsock, &fdsr))
				handle_replies();
			if (FD_ISSET(pingsock, &fdsr))
				handle_ping();
			svc_getreqset(&fdsr);
			if (check)
				checkwork();
			break;
		}

		if (!evil && ypbindlist->dom_alive) {
			evil = 1;
			daemon(0, 0);
		}
	}
}

/*
 * State transition is done like this:
 *
 * STATE	EVENT		ACTION			NEWSTATE	TIMEOUT
 * no binding	timeout		broadcast 		no binding	5 sec
 * no binding	answer		--			binding		60 sec
 * binding	timeout		ping server		checking	5 sec
 * checking	timeout		ping server + broadcast	checking	5 sec
 * checking	answer		--			binding		60 sec
 */
checkwork()
{
	struct _dom_binding *ypdb;
	time_t t;

	check = 0;

	time(&t);
	for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext) {
		if (ypdb->dom_check_t < t) {
			if (ypdb->dom_alive == 1)
				ping(ypdb);
			else
				broadcast(ypdb);
			time(&t);
			ypdb->dom_check_t = t + 5;
		}
	}
}

ping(ypdb)
	struct _dom_binding *ypdb;
{
	char *dom = ypdb->dom_domain;
	struct rpc_msg msg;
	char buf[1400];
	enum clnt_stat st;
	int outlen;
	AUTH *rpcua;
	XDR xdr;

	memset(&xdr, 0, sizeof xdr);
	memset(&msg, 0, sizeof msg);

	rpcua = authunix_create_default();
	if (rpcua == (AUTH *)NULL) {
		/*printf("cannot get unix auth\n");*/
		return RPC_SYSTEMERROR;
	}
	msg.rm_direction = CALL;
	msg.rm_call.cb_rpcvers = RPC_MSG_VERSION;
	msg.rm_call.cb_prog = YPPROG;
	msg.rm_call.cb_vers = YPVERS;
	msg.rm_call.cb_proc = YPPROC_DOMAIN_NONACK;
	msg.rm_call.cb_cred = rpcua->ah_cred;
	msg.rm_call.cb_verf = rpcua->ah_verf;

	msg.rm_xid = (long)dom;
	xdrmem_create(&xdr, buf, sizeof buf, XDR_ENCODE);
	if (!xdr_callmsg(&xdr, &msg)) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	if (!xdr_domainname(&xdr, dom)) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	outlen = (int)xdr_getpos(&xdr);
	xdr_destroy(&xdr);
	if (outlen < 1) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	AUTH_DESTROY(rpcua);

	ypdb->dom_alive = 2;
	if (sendto(pingsock, buf, outlen, 0,
		   (struct sockaddr *)&ypdb->dom_server_addr,
		   sizeof ypdb->dom_server_addr) < 0)
		perror("sendto");
	return 0;

}

broadcast(ypdb)
	struct _dom_binding *ypdb;
{
	char *dom = ypdb->dom_domain;
	struct rpc_msg msg;
	char buf[1400], inbuf[8192];
	char path[MAXPATHLEN];
	enum clnt_stat st;
	int outlen, i, sock, len;
	struct sockaddr_in bindsin;
	struct ifconf ifc;
	struct ifreq ifreq, *ifr;
	struct in_addr in;
	AUTH *rpcua;
	XDR xdr;

	rmtca.xdr_args = xdr_domainname;
	rmtca.args_ptr = dom;

	memset(&xdr, 0, sizeof xdr);
	memset(&msg, 0, sizeof msg);

	rpcua = authunix_create_default();
	if (rpcua == (AUTH *)NULL) {
		/*printf("cannot get unix auth\n");*/
		return RPC_SYSTEMERROR;
	}
	msg.rm_direction = CALL;
	msg.rm_call.cb_rpcvers = RPC_MSG_VERSION;
	msg.rm_call.cb_prog = PMAPPROG;
	msg.rm_call.cb_vers = PMAPVERS;
	msg.rm_call.cb_proc = PMAPPROC_CALLIT;
	msg.rm_call.cb_cred = rpcua->ah_cred;
	msg.rm_call.cb_verf = rpcua->ah_verf;

	msg.rm_xid = (long)dom;
	xdrmem_create(&xdr, buf, sizeof buf, XDR_ENCODE);
	if (!xdr_callmsg(&xdr, &msg)) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	if (!xdr_rmtcall_args(&xdr, &rmtca)) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	outlen = (int)xdr_getpos(&xdr);
	xdr_destroy(&xdr);
	if (outlen < 1) {
		st = RPC_CANTENCODEARGS;
		AUTH_DESTROY(rpcua);
		return st;
	}
	AUTH_DESTROY(rpcua);

	if (ypdb->dom_lockfd != -1) {
		close(ypdb->dom_lockfd);
		ypdb->dom_lockfd = -1;
		sprintf(path, "%s/%s.%d", BINDINGDIR,
			ypdb->dom_domain, ypdb->dom_vers);
		unlink(path);
	}

	memset(&bindsin, 0, sizeof bindsin);
	bindsin.sin_family = AF_INET;
	bindsin.sin_len = sizeof(bindsin);
	bindsin.sin_port = htons(PMAPPORT);

	if (ypdb->dom_alive == 2) {
		/*
		 * This resolves the following situation:
		 * ypserver on other subnet was once bound,
		 * but rebooted and is now using a different port
		 */
		bindsin.sin_addr = ypdb->dom_server_addr.sin_addr;
		if (sendto(rpcsock, buf, outlen, 0, (struct sockaddr *)&bindsin,
			   sizeof bindsin) < 0)
			perror("sendto");
	}
	/* find all networks and send the RPC packet out them all */
	if ((sock = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
		perror("socket");
		return -1;
	}

	ifc.ifc_len = sizeof inbuf;
	ifc.ifc_buf = inbuf;
	if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
		close(sock);
		perror("ioctl(SIOCGIFCONF)");
		return -1;
	}
	ifr = ifc.ifc_req;
	ifreq.ifr_name[0] = '\0';
	for (i = 0; i < ifc.ifc_len; i += len, ifr = (struct ifreq *)((caddr_t)ifr + len)) {
#if defined(BSD) && BSD >= 199103
		len = sizeof ifr->ifr_name + ifr->ifr_addr.sa_len;
#else
		len = sizeof ifc.ifc_len / sizeof(struct ifreq);
#endif
		ifreq = *ifr;
		if (ifreq.ifr_addr.sa_family != AF_INET)
			continue;
		if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0) {
			perror("ioctl(SIOCGIFFLAGS)");
			continue;
		}
		if ((ifreq.ifr_flags & IFF_UP) == 0)
			continue;

		ifreq.ifr_flags &= (IFF_LOOPBACK | IFF_BROADCAST);
		if (ifreq.ifr_flags == IFF_BROADCAST) {
			if (ioctl(sock, SIOCGIFBRDADDR, &ifreq) < 0) {
				perror("ioctl(SIOCGIFBRDADDR)");
				continue;
			}
		} else if (ifreq.ifr_flags == IFF_LOOPBACK) {
			if (ioctl(sock, SIOCGIFADDR, &ifreq) < 0) {
				perror("ioctl(SIOCGIFADDR)");
				continue;
			}
		} else
			continue;

		in = ((struct sockaddr_in *)&ifreq.ifr_addr)->sin_addr;
		bindsin.sin_addr = in;
		if (sendto(rpcsock, buf, outlen, 0, (struct sockaddr *)&bindsin,
			   sizeof bindsin) < 0)
			perror("sendto");
	}
	close(sock);
	return 0;
}

/*enum clnt_stat*/
handle_replies()
{
	char buf[1400];
	int fromlen, inlen;
	struct sockaddr_in raddr;
	struct rpc_msg msg;
	XDR xdr;

recv_again:
	memset(&xdr, 0, sizeof(xdr));
	memset(&msg, 0, sizeof(msg));
	msg.acpted_rply.ar_verf = _null_auth;
	msg.acpted_rply.ar_results.where = (caddr_t)&rmtcr;
	msg.acpted_rply.ar_results.proc = xdr_rmtcallres;

try_again:
	fromlen = sizeof (struct sockaddr);
	inlen = recvfrom(rpcsock, buf, sizeof buf, 0,
		(struct sockaddr *)&raddr, &fromlen);
	if (inlen < 0) {
		if (errno == EINTR)
			goto try_again;
		return RPC_CANTRECV;
	}
	if (inlen < sizeof(u_int32_t))
		goto recv_again;

	/*
	 * see if reply transaction id matches sent id.
	 * If so, decode the results.
	 */
	xdrmem_create(&xdr, buf, (u_int)inlen, XDR_DECODE);
	if (xdr_replymsg(&xdr, &msg)) {
		if ((msg.rm_reply.rp_stat == MSG_ACCEPTED) &&
		    (msg.acpted_rply.ar_stat == SUCCESS)) {
			raddr.sin_port = htons((u_short)rmtcr_port);
			rpc_received(msg.rm_xid, &raddr, 0);
		}
	}
	xdr.x_op = XDR_FREE;
	msg.acpted_rply.ar_results.proc = xdr_void;
	xdr_destroy(&xdr);

	return RPC_SUCCESS;
}

/*enum clnt_stat*/
handle_ping()
{
	char buf[1400];
	int fromlen, inlen;
	struct sockaddr_in raddr;
	struct rpc_msg msg;
	XDR xdr;
	bool_t res;

recv_again:
	memset(&xdr, 0, sizeof(xdr));
	memset(&msg, 0, sizeof(msg));
	msg.acpted_rply.ar_verf = _null_auth;
	msg.acpted_rply.ar_results.where = (caddr_t)&res;
	msg.acpted_rply.ar_results.proc = xdr_bool;

try_again:
	fromlen = sizeof (struct sockaddr);
	inlen = recvfrom(pingsock, buf, sizeof buf, 0,
		(struct sockaddr *)&raddr, &fromlen);
	if (inlen < 0) {
		if (errno == EINTR)
			goto try_again;
		return RPC_CANTRECV;
	}
	if (inlen < sizeof(u_int32_t))
		goto recv_again;

	/*
	 * see if reply transaction id matches sent id.
	 * If so, decode the results.
	 */
	xdrmem_create(&xdr, buf, (u_int)inlen, XDR_DECODE);
	if (xdr_replymsg(&xdr, &msg)) {
		if ((msg.rm_reply.rp_stat == MSG_ACCEPTED) &&
		    (msg.acpted_rply.ar_stat == SUCCESS)) {
			rpc_received(msg.rm_xid, &raddr, 0);
		}
	}
	xdr.x_op = XDR_FREE;
	msg.acpted_rply.ar_results.proc = xdr_void;
	xdr_destroy(&xdr);

	return RPC_SUCCESS;
}

/*
 * LOOPBACK IS MORE IMPORTANT: PUT IN HACK
 */
rpc_received(dom, raddrp, force)
char *dom;
struct sockaddr_in *raddrp;
int force;
{
	struct _dom_binding *ypdb;
	struct iovec iov[2];
	struct ypbind_resp ybr;
	char path[MAXPATHLEN];
	int fd;

	/* XXX XXX USING POINTERS OVER THE NET LIKE THIS IS TOTALLY WRONG. */

	/*printf("returned from %s about %s\n", inet_ntoa(raddrp->sin_addr), dom);*/

	if (dom == NULL)
		return;

	for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext)
		if (!strcmp(ypdb->dom_domain, dom))
			break;

	if (ypdb == NULL) {
		if (force == 0)
			return;
		ypdb = (struct _dom_binding *)malloc(sizeof *ypdb);
		memset(ypdb, 0, sizeof *ypdb);
		strncpy(ypdb->dom_domain, dom, sizeof ypdb->dom_domain);
		ypdb->dom_lockfd = -1;
		ypdb->dom_pnext = ypbindlist;
		ypbindlist = ypdb;
	}

	/* soft update, alive */
	if (ypdb->dom_alive == 1 && force == 0) {
		if (!memcmp(&ypdb->dom_server_addr, raddrp,
			    sizeof ypdb->dom_server_addr)) {
			ypdb->dom_alive = 1;
			ypdb->dom_check_t = time(NULL) + 60; /* recheck binding in 60 sec */
		}
		return;
	}

	memcpy(&ypdb->dom_server_addr, raddrp, sizeof ypdb->dom_server_addr);
	ypdb->dom_check_t = time(NULL) + 60;	/* recheck binding in 60 seconds */
	ypdb->dom_vers = YPVERS;
	ypdb->dom_alive = 1;

	if (ypdb->dom_lockfd != -1)
		close(ypdb->dom_lockfd);

	sprintf(path, "%s/%s.%d", BINDINGDIR,
		ypdb->dom_domain, ypdb->dom_vers);
#ifdef O_SHLOCK
	if ((fd = open(path, O_CREAT|O_SHLOCK|O_RDWR|O_TRUNC, 0644)) == -1) {
		(void)mkdir(BINDINGDIR, 0755);
		if ((fd = open(path, O_CREAT|O_SHLOCK|O_RDWR|O_TRUNC, 0644)) == -1)
			return;
	}
#else
	if ((fd = open(path, O_CREAT|O_RDWR|O_TRUNC, 0644)) == -1) {
		(void)mkdir(BINDINGDIR, 0755);
		if ((fd = open(path, O_CREAT|O_RDWR|O_TRUNC, 0644)) == -1)
			return;
	}
	flock(fd, LOCK_SH);
#endif

	/*
	 * ok, if BINDINGDIR exists, and we can create the binding file,
	 * then write to it..
	 */
	ypdb->dom_lockfd = fd;

	iov[0].iov_base = (caddr_t)&(udptransp->xp_port);
	iov[0].iov_len = sizeof udptransp->xp_port;
	iov[1].iov_base = (caddr_t)&ybr;
	iov[1].iov_len = sizeof ybr;

	memset(&ybr, 0, sizeof ybr);
	ybr.ypbind_status = YPBIND_SUCC_VAL;
	ybr.ypbind_respbody.ypbind_bindinfo.ypbind_binding_addr = raddrp->sin_addr;
	ybr.ypbind_respbody.ypbind_bindinfo.ypbind_binding_port = raddrp->sin_port;

	if (writev(ypdb->dom_lockfd, iov, 2) != iov[0].iov_len + iov[1].iov_len) {
		perror("write");
		close(ypdb->dom_lockfd);
		unlink(path);
		ypdb->dom_lockfd = -1;
		return;
	}
}