/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1992/3 Theo de Raadt <deraadt@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. 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.
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <ctype.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <rpc/rpc.h>
#include <rpc/xdr.h>
#include <net/if.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <rpc/pmap_clnt.h>
#include <rpc/pmap_prot.h>
#include <rpc/pmap_rmt.h>
#include <rpc/rpc_com.h>
#include <rpcsvc/yp.h>
#include <rpcsvc/ypclnt.h>
#include "yp_ping.h"

#ifndef BINDINGDIR
#define BINDINGDIR "/var/yp/binding"
#endif

#ifndef YPBINDLOCK
#define YPBINDLOCK "/var/run/ypbind.lock"
#endif

struct _dom_binding {
        struct _dom_binding *dom_pnext;
        char dom_domain[YPMAXDOMAIN + 1];
        struct sockaddr_in dom_server_addr;
        long int dom_vers;
        int dom_lockfd;
        int dom_alive;
        int dom_broadcast_pid;
        int dom_pipe_fds[2];
        int dom_default;
};

#define READFD ypdb->dom_pipe_fds[0]
#define WRITEFD ypdb->dom_pipe_fds[1]
#define BROADFD broad_domain->dom_pipe_fds[1]

void    checkwork(void);
void    *ypbindproc_null_2_yp(SVCXPRT *, void *, CLIENT *);
void    *ypbindproc_setdom_2_yp(SVCXPRT *, struct ypbind_setdom *, CLIENT *);
void    rpc_received(char *, struct sockaddr_in *, int);
void    broadcast(struct _dom_binding *);
int     ping(struct _dom_binding *);
int     tell_parent(char *, struct sockaddr_in *);
void    handle_children(struct _dom_binding *);
void    reaper(int);
void    terminate(int);
void    yp_restricted_mode(char *);
int     verify(struct in_addr);

static char *domain_name;
static struct _dom_binding *ypbindlist;
static struct _dom_binding *broad_domain;

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

#define NOT_RESPONDING_HYSTERESIS 10
static int not_responding_count = 0;

/*
 * Special restricted mode variables: when in restricted mode, only the
 * specified restricted_domain will be bound, and only the servers listed
 * in restricted_addrs will be used for binding.
 */
#define RESTRICTED_SERVERS 10
static int yp_restricted = 0;
static int yp_manycast = 0;
static struct in_addr restricted_addrs[RESTRICTED_SERVERS];

/* No more than MAX_CHILDREN child broadcasters at a time. */
#ifndef MAX_CHILDREN
#define MAX_CHILDREN 5
#endif
/* No more than MAX_DOMAINS simultaneous domains */
#ifndef MAX_DOMAINS
#define MAX_DOMAINS 200
#endif
/* RPC timeout value */
#ifndef FAIL_THRESHOLD
#define FAIL_THRESHOLD 20
#endif

/* Number of times to fish for a response froma particular set of hosts */
#ifndef MAX_RETRIES
#define MAX_RETRIES 30
#endif

static int retries = 0;
static int children = 0;
static int domains = 0;
static int yplockfd;
static fd_set fdsr;

static SVCXPRT *udptransp, *tcptransp;

void *
ypbindproc_null_2_yp(SVCXPRT *transp, void *argp, CLIENT *clnt)
{
        static char res;

        bzero(&res, sizeof(res));
        return &res;
}

static struct ypbind_resp *
ypbindproc_domain_2_yp(SVCXPRT *transp, domainname *argp, CLIENT *clnt)
{
        static struct ypbind_resp res;
        struct _dom_binding *ypdb;
        char path[MAXPATHLEN];

        bzero(&res, sizeof res);
        res.ypbind_status = YPBIND_FAIL_VAL;
        res.ypbind_resp_u.ypbind_error = YPBIND_ERR_NOSERV;

        if (strchr(*argp, '/')) {
                syslog(LOG_WARNING, "Domain name '%s' has embedded slash -- \
rejecting.", *argp);
                return(&res);
        }

        for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext) {
                if (strcmp(ypdb->dom_domain, *argp) == 0)
                        break;
                }

        if (ypdb == NULL) {
                if (yp_restricted) {
                        syslog(LOG_NOTICE, "Running in restricted mode -- request to bind domain \"%s\" rejected.\n", *argp);
                        return (&res);
                }

                if (domains >= MAX_DOMAINS) {
                        syslog(LOG_WARNING, "domain limit (%d) exceeded",
                                                        MAX_DOMAINS);
                        res.ypbind_resp_u.ypbind_error = YPBIND_ERR_RESC;
                        return (&res);
                }
                if (strlen(*argp) > YPMAXDOMAIN) {
                        syslog(LOG_WARNING, "domain %s too long", *argp);
                        res.ypbind_resp_u.ypbind_error = YPBIND_ERR_RESC;
                        return (&res);
                }
                ypdb = malloc(sizeof *ypdb);
                if (ypdb == NULL) {
                        syslog(LOG_WARNING, "malloc: %m");
                        res.ypbind_resp_u.ypbind_error = YPBIND_ERR_RESC;
                        return (&res);
                }
                bzero(ypdb, sizeof *ypdb);
                strlcpy(ypdb->dom_domain, *argp, sizeof ypdb->dom_domain);
                ypdb->dom_vers = YPVERS;
                ypdb->dom_alive = 0;
                ypdb->dom_default = 0;
                ypdb->dom_lockfd = -1;
                sprintf(path, "%s/%s.%ld", BINDINGDIR,
                                        ypdb->dom_domain, ypdb->dom_vers);
                unlink(path);
                ypdb->dom_pnext = ypbindlist;
                ypbindlist = ypdb;
                domains++;
        }

        if (ping(ypdb)) {
                return (&res);
        }

        res.ypbind_status = YPBIND_SUCC_VAL;
        res.ypbind_resp_u.ypbind_error = 0; /* Success */
        memcpy(&res.ypbind_resp_u.ypbind_bindinfo.ypbind_binding_addr,
            &ypdb->dom_server_addr.sin_addr.s_addr, sizeof(u_int32_t));
        memcpy(&res.ypbind_resp_u.ypbind_bindinfo.ypbind_binding_port,
            &ypdb->dom_server_addr.sin_port, sizeof(u_short));
        /*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);
}

void *
ypbindproc_setdom_2_yp(SVCXPRT *transp, ypbind_setdom *argp, CLIENT *clnt)
{
        struct sockaddr_in *fromsin, bindsin;
        static char             *result = NULL;

        if (strchr(argp->ypsetdom_domain, '/')) {
                syslog(LOG_WARNING, "Domain name '%s' has embedded slash -- \
rejecting.", argp->ypsetdom_domain);
                return(NULL);
        }
        fromsin = svc_getcaller(transp);

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

        if (ntohs(fromsin->sin_port) >= IPPORT_RESERVED) {
                svcerr_noprog(transp);
                return(NULL);
        }

        if (argp->ypsetdom_vers != YPVERS) {
                svcerr_noprog(transp);
                return(NULL);
        }

        bzero(&bindsin, sizeof bindsin);
        bindsin.sin_family = AF_INET;
        memcpy(&bindsin.sin_addr.s_addr,
            &argp->ypsetdom_binding.ypbind_binding_addr,
            sizeof(u_int32_t));
        memcpy(&bindsin.sin_port,
            &argp->ypsetdom_binding.ypbind_binding_port,
            sizeof(u_short));
        rpc_received(argp->ypsetdom_domain, &bindsin, 1);

        return((void *) &result);
}

void
ypbindprog_2(struct svc_req *rqstp, register SVCXPRT *transp)
{
        union {
                domainname ypbindproc_domain_2_arg;
                struct ypbind_setdom ypbindproc_setdom_2_arg;
        } argument;
        struct authunix_parms *creds;
        void *result;
        xdrproc_t xdr_argument, xdr_result;
        typedef void *(svc_cb)(SVCXPRT *transp, void *arg,
            struct svc_req *rqstp);
        svc_cb *local;

        switch (rqstp->rq_proc) {
        case YPBINDPROC_NULL:
                xdr_argument = (xdrproc_t)xdr_void;
                xdr_result = (xdrproc_t)xdr_void;
                local = (svc_cb *)ypbindproc_null_2_yp;
                break;

        case YPBINDPROC_DOMAIN:
                xdr_argument = (xdrproc_t)xdr_domainname;
                xdr_result = (xdrproc_t)xdr_ypbind_resp;
                local = (svc_cb *)ypbindproc_domain_2_yp;
                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 = (xdrproc_t)xdr_ypbind_setdom;
                xdr_result = (xdrproc_t)xdr_void;
                local = (svc_cb *)ypbindproc_setdom_2_yp;
                break;

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

/* Jack the reaper */
void
reaper(int sig)
{
        int st;

        while (wait3(&st, WNOHANG, NULL) > 0)
                children--;
}

void
terminate(int sig)
{
        struct _dom_binding *ypdb;
        char path[MAXPATHLEN];

        if (ppid != getpid())
                exit(0);

        for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext) {
                close(ypdb->dom_lockfd);
                if (ypdb->dom_broadcast_pid)
                        kill(ypdb->dom_broadcast_pid, SIGINT);
                sprintf(path, "%s/%s.%ld", BINDINGDIR,
                        ypdb->dom_domain, ypdb->dom_vers);
                unlink(path);
        }
        close(yplockfd);
        unlink(YPBINDLOCK);
        pmap_unset(YPBINDPROG, YPBINDVERS);
        exit(0);
}

int
main(int argc, char *argv[])
{
        struct timeval tv;
        int i;
        DIR *dird;
        struct dirent *dirp;
        struct _dom_binding *ypdb, *next;

        /* Check that another ypbind isn't already running. */
        if ((yplockfd = (open(YPBINDLOCK, O_RDONLY|O_CREAT, 0444))) == -1)
                err(1, "%s", YPBINDLOCK);

        if (flock(yplockfd, LOCK_EX|LOCK_NB) == -1 && errno == EWOULDBLOCK)
                errx(1, "another ypbind is already running. Aborting");

        /* XXX domainname will be overridden if we use restricted mode */
        yp_get_default_domain(&domain_name);
        if (domain_name[0] == '\0')
                errx(1, "domainname not set. Aborting");

        for (i = 1; i<argc; i++) {
                if (strcmp("-ypset", argv[i]) == 0)
                        ypsetmode = YPSET_ALL;
                else if (strcmp("-ypsetme", argv[i]) == 0)
                        ypsetmode = YPSET_LOCAL;
                else if (strcmp("-s", argv[i]) == 0)
                        ypsecuremode++;
                else if (strcmp("-S", argv[i]) == 0 && argc > i)
                        yp_restricted_mode(argv[++i]);
                else if (strcmp("-m", argv[i]) == 0)
                        yp_manycast++;
                else
                        errx(1, "unknown option: %s", argv[i]);
        }

        if (strlen(domain_name) > YPMAXDOMAIN)
                warnx("truncating domain name %s", domain_name);

        /* blow away everything in BINDINGDIR (if it exists) */

        if ((dird = opendir(BINDINGDIR)) != NULL) {
                char path[MAXPATHLEN];
                while ((dirp = readdir(dird)) != NULL)
                        if (strcmp(dirp->d_name, ".") &&
                            strcmp(dirp->d_name, "..")) {
                                sprintf(path,"%s/%s",BINDINGDIR,dirp->d_name);
                                unlink(path);
                        }
                closedir(dird);
        }

#ifdef DAEMON
        if (daemon(0,0))
                err(1, "fork");
#endif

        pmap_unset(YPBINDPROG, YPBINDVERS);

        udptransp = svcudp_create(RPC_ANYSOCK);
        if (udptransp == NULL)
                errx(1, "cannot create udp service");
        if (!svc_register(udptransp, YPBINDPROG, YPBINDVERS, ypbindprog_2,
            IPPROTO_UDP))
                errx(1, "unable to register (YPBINDPROG, YPBINDVERS, udp)");

        tcptransp = svctcp_create(RPC_ANYSOCK, 0, 0);
        if (tcptransp == NULL)
                errx(1, "cannot create tcp service");

        if (!svc_register(tcptransp, YPBINDPROG, YPBINDVERS, ypbindprog_2,
            IPPROTO_TCP))
                errx(1, "unable to register (YPBINDPROG, YPBINDVERS, tcp)");

        /* build initial domain binding, make it "unsuccessful" */
        ypbindlist = malloc(sizeof *ypbindlist);
        if (ypbindlist == NULL)
                errx(1, "malloc");
        bzero(ypbindlist, sizeof *ypbindlist);
        strlcpy(ypbindlist->dom_domain, domain_name, sizeof ypbindlist->dom_domain);
        ypbindlist->dom_vers = YPVERS;
        ypbindlist->dom_alive = 0;
        ypbindlist->dom_lockfd = -1;
        ypbindlist->dom_default = 1;
        domains++;

        signal(SIGCHLD, reaper);
        signal(SIGTERM, terminate);

        ppid = getpid(); /* Remember who we are. */

        openlog(argv[0], LOG_PID, LOG_DAEMON);

        if (madvise(NULL, 0, MADV_PROTECT) != 0)
                syslog(LOG_WARNING, "madvise(): %m");

        /* Kick off the default domain */
        broadcast(ypbindlist);

        while (1) {
                fdsr = svc_fdset;

                tv.tv_sec = 60;
                tv.tv_usec = 0;

                switch (select(_rpc_dtablesize(), &fdsr, NULL, NULL, &tv)) {
                case 0:
                        checkwork();
                        break;
                case -1:
                        if (errno != EINTR)
                                syslog(LOG_WARNING, "select: %m");
                        break;
                default:
                        for (ypdb = ypbindlist; ypdb; ypdb = next) {
                                next = ypdb->dom_pnext;
                                if (READFD > 0 && FD_ISSET(READFD, &fdsr)) {
                                        handle_children(ypdb);
                                        if (children == (MAX_CHILDREN - 1))
                                                checkwork();
                                }
                        }
                        svc_getreqset(&fdsr);
                        break;
                }
        }

        /* NOTREACHED */
        exit(1);
}

void
checkwork(void)
{
        struct _dom_binding *ypdb;

        for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext)
                ping(ypdb);
}

/* The clnt_broadcast() callback mechanism sucks. */

/*
 * Receive results from broadcaster. Don't worry about passing
 * bogus info to rpc_received() -- it can handle it. Note that we
 * must be sure to invalidate the dom_pipe_fds descriptors here:
 * since descriptors can be re-used, we have to make sure we
 * don't mistake one of the RPC descriptors for one of the pipes.
 * What's weird is that forgetting to invalidate the pipe descriptors
 * doesn't always result in an error (otherwise I would have caught
 * the mistake much sooner), even though logically it should.
 */
void
handle_children(struct _dom_binding *ypdb)
{
        char buf[YPMAXDOMAIN + 1];
        struct sockaddr_in addr;
        int d = 0, a = 0;
        struct _dom_binding *y, *prev = NULL;
        char path[MAXPATHLEN];

        if ((d = read(READFD, &buf, sizeof(buf))) <= 0)
                syslog(LOG_WARNING, "could not read from child: %m");

        if ((a = read(READFD, &addr, sizeof(struct sockaddr_in))) < 0)
                syslog(LOG_WARNING, "could not read from child: %m");

        close(READFD);
        FD_CLR(READFD, &fdsr);
        FD_CLR(READFD, &svc_fdset);
        READFD = WRITEFD = -1;
        if (d > 0 && a > 0)
                rpc_received(buf, &addr, 0);
        else {
                for (y = ypbindlist; y; y = y->dom_pnext) {
                        if (y == ypdb)
                                break;
                        prev = y;
                }
                switch (ypdb->dom_default) {
                case 0:
                        if (prev == NULL)
                                ypbindlist = y->dom_pnext;
                        else
                                prev->dom_pnext = y->dom_pnext;
                        sprintf(path, "%s/%s.%ld", BINDINGDIR,
                                ypdb->dom_domain, YPVERS);
                        close(ypdb->dom_lockfd);
                        unlink(path);
                        free(ypdb);
                        domains--;
                        return;
                case 1:
                        ypdb->dom_broadcast_pid = 0;
                        ypdb->dom_alive = 0;
                        broadcast(ypdb);
                        return;
                default:
                        break;
                }
        }

        return;
}

/*
 * Send our dying words back to our parent before we perish.
 */
int
tell_parent(char *dom, struct sockaddr_in *addr)
{
        char buf[YPMAXDOMAIN + 1];
        struct timeval timeout;
        fd_set fds;

        timeout.tv_sec = 5;
        timeout.tv_usec = 0;

        sprintf(buf, "%s", broad_domain->dom_domain);
        if (write(BROADFD, &buf, sizeof(buf)) < 0)
                return(1);

        /*
         * Stay in sync with parent: wait for it to read our first
         * message before sending the second.
         */

        FD_ZERO(&fds);
        FD_SET(BROADFD, &fds);
        if (select(FD_SETSIZE, NULL, &fds, NULL, &timeout) == -1)
                return(1);
        if (FD_ISSET(BROADFD, &fds)) {
                if (write(BROADFD, addr, sizeof(struct sockaddr_in)) < 0)
                        return(1);
        } else {
                return(1);
        }

        close(BROADFD);
        return (0);
}

static bool_t
broadcast_result(bool_t *out, struct sockaddr_in *addr)
{
        if (retries >= MAX_RETRIES) {
                bzero(addr, sizeof(struct sockaddr_in));
                if (tell_parent(broad_domain->dom_domain, addr))
                        syslog(LOG_WARNING, "lost connection to parent");
                return (TRUE);
        }

        if (yp_restricted && verify(addr->sin_addr)) {
                retries++;
                syslog(LOG_NOTICE, "NIS server at %s not in restricted mode access list -- rejecting.\n",inet_ntoa(addr->sin_addr));
                return (FALSE);
        } else {
                if (tell_parent(broad_domain->dom_domain, addr))
                        syslog(LOG_WARNING, "lost connection to parent");
                return (TRUE);
        }
}

/*
 * The right way to send RPC broadcasts.
 * Use the clnt_broadcast() RPC service. Unfortunately, clnt_broadcast()
 * blocks while waiting for replies, so we have to fork off separate
 * broadcaster processes that do the waiting and then transmit their
 * results back to the parent for processing. We also have to remember
 * to save the name of the domain we're trying to bind in a global
 * variable since clnt_broadcast() provides no way to pass things to
 * the 'eachresult' callback function.
 */
void
broadcast(struct _dom_binding *ypdb)
{
        bool_t out = FALSE;
        enum clnt_stat stat;

        if (children >= MAX_CHILDREN || ypdb->dom_broadcast_pid)
                return;

        if (pipe(ypdb->dom_pipe_fds) < 0) {
                syslog(LOG_WARNING, "pipe: %m");
                return;
        }

        if (ypdb->dom_vers == -1 && (long)ypdb->dom_server_addr.sin_addr.s_addr) {
                if (not_responding_count++ >= NOT_RESPONDING_HYSTERESIS) {
                        not_responding_count = NOT_RESPONDING_HYSTERESIS;
                        syslog(LOG_WARNING, "NIS server [%s] for domain \"%s\" not responding",
                            inet_ntoa(ypdb->dom_server_addr.sin_addr), ypdb->dom_domain);
                }
        }

        broad_domain = ypdb;
        flock(ypdb->dom_lockfd, LOCK_UN);

        switch ((ypdb->dom_broadcast_pid = fork())) {
        case 0:
                close(READFD);
                signal(SIGCHLD, SIG_DFL);
                signal(SIGTERM, SIG_DFL);
                break;
        case -1:
                syslog(LOG_WARNING, "fork: %m");
                close(READFD);
                close(WRITEFD);
                return;
        default:
                close(WRITEFD);
                FD_SET(READFD, &svc_fdset);
                children++;
                return;
        }

        /* Release all locks before doing anything else. */
        while (ypbindlist) {
                close(ypbindlist->dom_lockfd);
                ypbindlist = ypbindlist->dom_pnext;
        }
        close(yplockfd);

        /*
         * Special 'many-cast' behavior. If we're in restricted mode,
         * we have a list of possible server addresses to try. What
         * we can do is transmit to each ypserv's YPPROC_DOMAIN_NONACK
         * procedure and time the replies. Whoever replies fastest
         * gets to be our server. Note that this is not a broadcast
         * operation: we transmit uni-cast datagrams only.
         */
        if (yp_restricted && yp_manycast) {
                short                   port;
                int                     i;
                struct sockaddr_in      sin;

                i = __yp_ping(restricted_addrs, yp_restricted,
                                ypdb->dom_domain, &port);
                if (i == -1) {
                        bzero(&ypdb->dom_server_addr,
                            sizeof(struct sockaddr_in));
                        if (tell_parent(ypdb->dom_domain,
                                &ypdb->dom_server_addr))
                        syslog(LOG_WARNING, "lost connection to parent");
                } else {
                        bzero(&sin, sizeof(struct sockaddr_in));
                        bcopy(&restricted_addrs[i],
                            &sin.sin_addr, sizeof(struct in_addr));
                        sin.sin_family = AF_INET;
                        sin.sin_port = port;
                        if (tell_parent(broad_domain->dom_domain, &sin))
                                syslog(LOG_WARNING,
                                        "lost connection to parent");
                }
                _exit(0);
        }

        retries = 0;

        {
                char *ptr;

                ptr = ypdb->dom_domain;
                stat = clnt_broadcast(YPPROG, YPVERS, YPPROC_DOMAIN_NONACK,
                        (xdrproc_t)xdr_domainname, &ptr,
                        (xdrproc_t)xdr_bool, &out,
                        (clnt_broadcast_resultproc_t)broadcast_result);
        }

        if (stat != RPC_SUCCESS) {
                bzero(&ypdb->dom_server_addr,
                    sizeof(struct sockaddr_in));
                if (tell_parent(ypdb->dom_domain, &ypdb->dom_server_addr))
                        syslog(LOG_WARNING, "lost connection to parent");
        }

        _exit(0);
}

/*
 * The right way to check if a server is alive.
 * Attempt to get a client handle pointing to the server and send a
 * YPPROC_DOMAIN. If we can't get a handle or we get a reply of FALSE,
 * we invalidate this binding entry and send out a broadcast to try to
 * establish a new binding. Note that we treat non-default domains
 * specially: once bound, we keep tabs on our server, but if it
 * goes away and fails to respond after one round of broadcasting, we
 * abandon it until a client specifically references it again. We make
 * every effort to keep our default domain bound, however, since we
 * need it to keep the system on its feet.
 */
int
ping(struct _dom_binding *ypdb)
{
        bool_t out;
        struct timeval interval, timeout;
        enum clnt_stat stat;
        int rpcsock = RPC_ANYSOCK;
        CLIENT *client_handle;

        interval.tv_sec = FAIL_THRESHOLD;
        interval.tv_usec = 0;
        timeout.tv_sec = FAIL_THRESHOLD;
        timeout.tv_usec = 0;

        if (ypdb->dom_broadcast_pid)
                return(1);

        if ((client_handle = clntudp_bufcreate(&ypdb->dom_server_addr,
                YPPROG, YPVERS, interval, &rpcsock, RPCSMALLMSGSIZE,
                RPCSMALLMSGSIZE)) == (CLIENT *)NULL) {
                /* Can't get a handle: we're dead. */
                ypdb->dom_alive = 0;
                ypdb->dom_vers = -1;
                broadcast(ypdb);
                return(1);
        }

        {
                char *ptr;

                ptr = ypdb->dom_domain;

                stat = clnt_call(client_handle, YPPROC_DOMAIN,
                    (xdrproc_t)xdr_domainname, &ptr,
                    (xdrproc_t)xdr_bool, &out, timeout);
                if (stat != RPC_SUCCESS || out == FALSE) {
                        ypdb->dom_alive = 0;
                        ypdb->dom_vers = -1;
                        clnt_destroy(client_handle);
                        broadcast(ypdb);
                        return(1);
                }
        }

        clnt_destroy(client_handle);
        return(0);
}

void
rpc_received(char *dom, struct sockaddr_in *raddrp, int force)
{
        struct _dom_binding *ypdb, *prev = NULL;
        struct iovec iov[2];
        struct ypbind_resp ybr;
        char path[MAXPATHLEN];
        int fd;

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

        if (dom == NULL)
                return;

        for (ypdb = ypbindlist; ypdb; ypdb = ypdb->dom_pnext) {
                if (strcmp(ypdb->dom_domain, dom) == 0)
                        break;
                prev = ypdb;
        }

        if (ypdb && force) {
                if (ypdb->dom_broadcast_pid) {
                        kill(ypdb->dom_broadcast_pid, SIGINT);
                        close(READFD);
                        FD_CLR(READFD, &fdsr);
                        FD_CLR(READFD, &svc_fdset);
                        READFD = WRITEFD = -1;
                }
        }

        /* if in secure mode, check originating port number */
        if ((ypsecuremode && (ntohs(raddrp->sin_port) >= IPPORT_RESERVED))) {
            syslog(LOG_WARNING, "Rejected NIS server on [%s/%d] for domain %s.",
                   inet_ntoa(raddrp->sin_addr), ntohs(raddrp->sin_port),
                   dom);
            if (ypdb != NULL) {
                ypdb->dom_broadcast_pid = 0;
                ypdb->dom_alive = 0;
            }
            return;
        }

        if (raddrp->sin_addr.s_addr == (long)0) {
                switch (ypdb->dom_default) {
                case 0:
                        if (prev == NULL)
                                ypbindlist = ypdb->dom_pnext;
                        else
                                prev->dom_pnext = ypdb->dom_pnext;
                        sprintf(path, "%s/%s.%ld", BINDINGDIR,
                                ypdb->dom_domain, YPVERS);
                        close(ypdb->dom_lockfd);
                        unlink(path);
                        free(ypdb);
                        domains--;
                        return;
                case 1:
                        ypdb->dom_broadcast_pid = 0;
                        ypdb->dom_alive = 0;
                        broadcast(ypdb);
                        return;
                default:
                        break;
                }
        }

        if (ypdb == NULL) {
                if (force == 0)
                        return;
                if (strlen(dom) > YPMAXDOMAIN) {
                        syslog(LOG_WARNING, "domain %s too long", dom);
                        return;
                }
                ypdb = malloc(sizeof *ypdb);
                if (ypdb == NULL) {
                        syslog(LOG_WARNING, "malloc: %m");
                        return;
                }
                bzero(ypdb, sizeof *ypdb);
                strlcpy(ypdb->dom_domain, dom, sizeof ypdb->dom_domain);
                ypdb->dom_lockfd = -1;
                ypdb->dom_default = 0;
                ypdb->dom_pnext = ypbindlist;
                ypbindlist = ypdb;
        }

        /* We've recovered from a crash: inform the world. */
        if (ypdb->dom_vers == -1 && ypdb->dom_server_addr.sin_addr.s_addr) {
                if (not_responding_count >= NOT_RESPONDING_HYSTERESIS) {
                        not_responding_count = 0;
                        syslog(LOG_WARNING, "NIS server [%s] for domain \"%s\" OK",
                            inet_ntoa(raddrp->sin_addr), ypdb->dom_domain);
                }
        }

        bcopy(raddrp, &ypdb->dom_server_addr,
                sizeof ypdb->dom_server_addr);

        ypdb->dom_vers = YPVERS;
        ypdb->dom_alive = 1;
        ypdb->dom_broadcast_pid = 0;

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

        sprintf(path, "%s/%s.%ld", 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 = (char *)&(udptransp->xp_port);
        iov[0].iov_len = sizeof udptransp->xp_port;
        iov[1].iov_base = (char *)&ybr;
        iov[1].iov_len = sizeof ybr;

        bzero(&ybr, sizeof ybr);
        ybr.ypbind_status = YPBIND_SUCC_VAL;
        memcpy(&ybr.ypbind_resp_u.ypbind_bindinfo.ypbind_binding_addr,
            &raddrp->sin_addr.s_addr, sizeof(u_int32_t));
        memcpy(&ybr.ypbind_resp_u.ypbind_bindinfo.ypbind_binding_port,
            &raddrp->sin_port, sizeof(u_short));

        if (writev(ypdb->dom_lockfd, iov, 2) != iov[0].iov_len + iov[1].iov_len) {
                syslog(LOG_WARNING, "write: %m");
                close(ypdb->dom_lockfd);
                ypdb->dom_lockfd = -1;
                return;
        }
}

/*
 * Check address against list of allowed servers. Return 0 if okay,
 * 1 if not matched.
 */
int
verify(struct in_addr addr)
{
        int i;

        for (i = 0; i < RESTRICTED_SERVERS; i++)
                if (!bcmp(&addr, &restricted_addrs[i], sizeof(struct in_addr)))
                        return(0);

        return(1);
}

/*
 * Try to set restricted mode. We default to normal mode if we can't
 * resolve the specified hostnames.
 */
void
yp_restricted_mode(char *args)
{
        struct hostent *h;
        int i = 0;
        char *s;

        /* Find the restricted domain. */
        if ((s = strsep(&args, ",")) == NULL)
                return;
        domain_name = s;

        /* Get the addresses of the servers. */
        while ((s = strsep(&args, ",")) != NULL && i < RESTRICTED_SERVERS) {
                if ((h = gethostbyname(s)) == NULL)
                        return;
                bcopy (h->h_addr_list[0], &restricted_addrs[i],
                    sizeof(struct in_addr));
                i++;
        }

        /* ypset and ypsetme not allowed with restricted mode */
        ypsetmode = YPSET_NO;

        yp_restricted = i;
        return;
}