/*      $NetBSD: ypserv.c,v 1.27 2021/03/07 15:09:13 christos Exp $     */

/*
 * Copyright (c) 1994 Mats O Jansson <moj@stacken.kth.se>
 * 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.
 *
 * 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/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: ypserv.c,v 1.27 2021/03/07 15:09:13 christos Exp $");
#endif

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>

#include <err.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <util.h>
#include <stdarg.h>
#include <errno.h>

#include <rpc/rpc.h>
#include <rpc/xdr.h>
#include <rpc/pmap_clnt.h>

#include <rpcsvc/yp_prot.h>

#include "ypdef.h"
#include "ypserv.h"

#ifdef LIBWRAP
#include <tcpd.h>

int allow_severity = LOG_DAEMON | LOG_INFO;
int deny_severity = LOG_DAEMON | LOG_WARNING;

/* XXX For ypserv_proc.c -- NOT THREAD SAFE!  (like any of this code is) */
const char *clientstr;
const char *svcname;
#endif /* LIBWRAP */

int     usedns;
#ifdef DEBUG
static int      foreground = 1;
#else
static int      foreground;
#endif

#ifdef LIBWRAP
int     lflag;
#endif

static struct bindsock {
        sa_family_t family;
        int type;
        int proto;
        const char *name;
} socklist[] = {
        { AF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp" },
        { AF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp" },
        { AF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp6" },
        { AF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp6" },
};

static void     usage(void) __dead;
static int      bind_resv_port(int, sa_family_t, in_port_t);
void            ypserv_sock_hostname(struct host_info *host);

static __printflike(2, 3) void
_msgout(int level, const char *msg, ...)
{
        va_list ap;
        va_start(ap, msg);
        if (foreground)
                vwarnx(msg, ap);
        else
                vsyslog(level, msg, ap);
        va_end(ap);
}

void ypserv_sock_hostname(struct host_info *host)
{
        host->name[0] = 0;
}

static void
ypprog_2(struct svc_req *rqstp, SVCXPRT *transp)
{
        union {
                char * ypproc_domain_2_arg;
                char * ypproc_domain_nonack_2_arg;
                struct ypreq_key ypproc_match_2_arg;
                struct ypreq_nokey ypproc_first_2_arg;
                struct ypreq_key ypproc_next_2_arg;
                struct ypreq_xfr ypproc_xfr_2_arg;
                struct ypreq_nokey ypproc_all_2_arg;
                struct ypreq_nokey ypproc_master_2_arg;
                struct ypreq_nokey ypproc_order_2_arg;
                char * ypproc_maplist_2_arg;
        } argument;
        void *argp = &argument;
        char *result;
        xdrproc_t xdr_argument, xdr_result;
        void *(*local)(void *, struct svc_req *);
#ifdef LIBWRAP
        struct request_info req;
        struct sockaddr *caller;
#define SVCNAME(x)      svcname = x
#else
#define SVCNAME(x)      /* nothing */
#endif

#ifdef LIBWRAP
        caller = svc_getrpccaller(transp)->buf;
        (void)request_init(&req, RQ_DAEMON, getprogname(), RQ_CLIENT_SIN,
            caller, RQ_FILE, transp->xp_fd, NULL);
        sock_methods(&req);

        /*
         * Do not do hostname lookups!  This avoids possible delays due
         * to DNS, preventing a possible DoS attack, as well as possible 
         * circular lookups (e.g. a hostname lookup requiring a request 
         * to ourselves).
         */
        req.hostname = ypserv_sock_hostname;
#endif

        switch (rqstp->rq_proc) {
        case YPPROC_NULL:
                xdr_argument = (xdrproc_t)xdr_void;
                xdr_result = (xdrproc_t)xdr_void;
                local = ypproc_null_2_svc;
                SVCNAME("null_2");
                break;

        case YPPROC_DOMAIN:
                xdr_argument = (xdrproc_t)xdr_ypdomain_wrap_string;
                xdr_result = (xdrproc_t)xdr_bool;
                local = ypproc_domain_2_svc;
                SVCNAME("domain_2");
                break;

        case YPPROC_DOMAIN_NONACK:
                xdr_argument = (xdrproc_t)xdr_ypdomain_wrap_string;
                xdr_result = (xdrproc_t)xdr_bool;
                local = ypproc_domain_nonack_2_svc;
                SVCNAME("domain_nonack_2");
                break;

        case YPPROC_MATCH:
                xdr_argument = (xdrproc_t)xdr_ypreq_key;
                xdr_result = (xdrproc_t)xdr_ypresp_val;
                local = ypproc_match_2_svc;
                SVCNAME("match_2");
                break;

        case YPPROC_FIRST:
                xdr_argument = (xdrproc_t)xdr_ypreq_nokey;
                xdr_result = (xdrproc_t)xdr_ypresp_key_val;
                local = ypproc_first_2_svc;
                SVCNAME("first_2");
                break;

        case YPPROC_NEXT:
                xdr_argument = (xdrproc_t)xdr_ypreq_key;
                xdr_result = (xdrproc_t)xdr_ypresp_key_val;
                local = ypproc_next_2_svc;
                SVCNAME("next_2");
                break;

        case YPPROC_XFR:
                xdr_argument = (xdrproc_t)xdr_ypreq_xfr;
                xdr_result = (xdrproc_t)xdr_ypresp_xfr;
                local = ypproc_xfr_2_svc;
                SVCNAME("xfer_2");
                break;

        case YPPROC_CLEAR:
                xdr_argument = (xdrproc_t)xdr_void;
                xdr_result = (xdrproc_t)xdr_void;
                local = ypproc_clear_2_svc;
                SVCNAME("clear_2");
                break;

        case YPPROC_ALL:
                xdr_argument = (xdrproc_t)xdr_ypreq_nokey;
                xdr_result = (xdrproc_t)xdr_ypresp_all;
                local = ypproc_all_2_svc;
                SVCNAME("all_2");
                break;

        case YPPROC_MASTER:
                xdr_argument = (xdrproc_t)xdr_ypreq_nokey;
                xdr_result = (xdrproc_t)xdr_ypresp_master;
                local = ypproc_master_2_svc;
                SVCNAME("master_2");
                break;

        case YPPROC_ORDER:
                xdr_argument = (xdrproc_t)xdr_ypreq_nokey;
                xdr_result = (xdrproc_t)xdr_ypresp_order;
                local = ypproc_order_2_svc;
                SVCNAME("order_2");
                break;

        case YPPROC_MAPLIST:
                xdr_argument = (xdrproc_t)xdr_ypdomain_wrap_string;
                xdr_result = (xdrproc_t)xdr_ypresp_maplist;
                local = ypproc_maplist_2_svc;
                SVCNAME("maplist_2");
                break;

        default:
                svcerr_noproc(transp);
                return;
        }

#ifdef LIBWRAP
        clientstr = eval_client(&req);

        if (hosts_access(&req) == 0) {
                syslog(deny_severity,
                    "%s: refused request from %.500s", svcname, clientstr);
                svcerr_auth(transp, AUTH_FAILED);
                return;
        }
#endif

        (void)memset(&argument, 0, sizeof (argument));
        if (!svc_getargs(transp, xdr_argument, argp)) {
                svcerr_decode(transp);
                return;
        }
        result = (*local)(&argument, rqstp);
        if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
                svcerr_systemerr(transp);
        }
        if (!svc_freeargs(transp, xdr_argument, argp)) {
                _msgout(LOG_ERR, "unable to free arguments");
                exit(1);
        }
        return;
}

/*
 * limited NIS version 1 support: the null, domain, and domain_nonack
 * request/reply format is identical between v1 and v2.  SunOS4's ypbind
 * makes v1 domain_nonack calls.
 */
static void
ypprog_1(struct svc_req *rqstp, SVCXPRT *transp)
{
        switch (rqstp->rq_proc) {
        case YPPROC_NULL:
        case YPPROC_DOMAIN:
        case YPPROC_DOMAIN_NONACK:
                ypprog_2(rqstp, transp);
                return;

        default:
                svcerr_noproc(transp);
                return;
        }
}

int
main(int argc, char *argv[])
{
        SVCXPRT *xprt;
        struct netconfig *cfg = NULL;
        int s;
        struct sigaction sa;
        struct bindsock *bs;
        in_port_t port = 0;
        int ch, xcreated = 0, one = 1;

        setprogname(argv[0]);

#ifdef LIBWRAP
#define GETOPTSTR       "dflp:"
#else
#define GETOPTSTR       "dfp:"
#endif
        while ((ch = getopt(argc, argv, GETOPTSTR)) != -1) {
                switch (ch) {
                case 'd':
                        usedns = 1;
                        break;
                case 'f':
                        foreground = 1;
                        break;
                case 'p':
                        port = atoi(optarg);
                        break;
#ifdef LIBWRAP
                case 'l':
                        lflag = 1;
                        break;
#endif
                default:
                        usage();
                }
        }

#undef GETOPTSTR

        /* This program must be run by root. */
        if (geteuid() != 0)
                errx(1, "must run as root");

        if (foreground == 0 && daemon(0, 0))
                err(1, "can't detach");

        openlog("ypserv", LOG_PID, LOG_DAEMON);
        syslog(LOG_INFO, "starting");
        (void)pidfile(NULL);

        (void) rpcb_unset((u_int)YPPROG, (u_int)YPVERS, NULL);
        (void) rpcb_unset((u_int)YPPROG, (u_int)YPVERS_ORIG, NULL);


        ypdb_init();    /* init db stuff */

        sa.sa_handler = SIG_IGN;
        sa.sa_flags = SA_NOCLDWAIT;
        if (sigemptyset(&sa.sa_mask)) {
                _msgout(LOG_ERR, "sigemptyset: %s", strerror(errno));
                exit(1);
        }
        if (sigaction(SIGCHLD, &sa, NULL)) {
                _msgout(LOG_ERR, "sigaction: %s", strerror(errno));
                exit(1);
        }

        for (bs = socklist;
            bs < &socklist[sizeof(socklist) / sizeof(socklist[0])]; bs++) {

                if ((s = socket(bs->family, bs->type, bs->proto)) == -1)
                        continue;

                if (bs->family == AF_INET6) {
                        /*
                         * We're doing host-based access checks here, so don't
                         * allow v4-in-v6 to confuse things.
                         */
                        if (setsockopt(s, IPPROTO_IPV6,
                            IPV6_V6ONLY, &one, sizeof(one)) == -1) {
                                _msgout(LOG_ERR, 
                                    "can't disable v4-in-v6 on %s socket",
                                    bs->name);
                                exit(1);
                        }
                }

                if ((cfg = getnetconfigent(bs->name)) == NULL) {
                        _msgout(LOG_ERR,
                            "unable to get network configuration for %s port",
                            bs->name);
                        goto out;
                }

                if (bind_resv_port(s, bs->family, port) != 0)
                        goto out;

                if (bs->type == SOCK_STREAM) {
                        (void)listen(s, SOMAXCONN);
                        xprt = svc_vc_create(s, 0, 0);
                } else {
                        xprt = svc_dg_create(s, 0, 0);
                }

                if (xprt == NULL) {
                        _msgout(LOG_WARNING, "unable to create %s service",
                            bs->name);
                        goto out;
                }
                if (svc_reg(xprt, (u_int)YPPROG, (u_int)YPVERS_ORIG, ypprog_1,
                    cfg) == 0 ||
                    svc_reg(xprt, (u_int)YPPROG, (u_int)YPVERS, ypprog_2,
                    cfg) == 0) {
                        _msgout(LOG_WARNING, "unable to register %s service",
                            bs->name);
                        goto out;
                }
                xcreated++;
                freenetconfigent(cfg);
                continue;
out:
                if (s != -1)
                        (void)close(s);
                if (cfg) {
                        freenetconfigent(cfg);
                        cfg = NULL;
                }
        }

        if (xcreated == 0) {
                _msgout(LOG_ERR, "unable to create any services");
                exit(1);
        }

        svc_run();
        _msgout(LOG_ERR, "svc_run returned");
        exit(1);
        /* NOTREACHED */
}

static void
usage(void)
{

#ifdef LIBWRAP
#define USAGESTR        "Usage: %s [-dfl] [-p <port>]\n"
#else
#define USAGESTR        "Usage: %s [-df] [-p <port>]\n"
#endif

        (void)fprintf(stderr, USAGESTR, getprogname());
        exit(1);

#undef USAGESTR
}

/*
 * _yp_invalid_map: check if given map name isn't legal.
 * returns non-zero if invalid
 *
 * XXX: this probably should be in libc/yp/yplib.c
 */
int
_yp_invalid_map(const char *map)
{
        if (map == NULL || *map == '\0')
                return 1;

        if (strlen(map) > YPMAXMAP)
                return 1;

        if (strchr(map, '/') != NULL)
                return 1;

        return 0;
}

static int
bind_resv_port(int sock, sa_family_t family, in_port_t port)
{
        struct sockaddr *sa;
        struct sockaddr_in sasin;
        struct sockaddr_in6 sasin6;

        switch (family) {
        case AF_INET:
                (void)memset(&sasin, 0, sizeof(sasin));
                sasin.sin_len = sizeof(sasin);
                sasin.sin_family = family;
                sasin.sin_port = htons(port);
                sa = (struct sockaddr *)(void *)&sasin;
                break;
        case AF_INET6:
                (void)memset(&sasin6, 0, sizeof(sasin6));
                sasin6.sin6_len = sizeof(sasin6);
                sasin6.sin6_family = family;
                sasin6.sin6_port = htons(port);
                sa = (struct sockaddr *)(void *)&sasin6;
                break;
        default:
                _msgout(LOG_ERR, "Unsupported address family %d", family);
                return -1;
        }
        if (bindresvport_sa(sock, sa) == -1) {
                _msgout(LOG_ERR, "Cannot bind to reserved port %d (%s)", port,
                    strerror(errno));
                return -1;
        }
        return 0;
}