libexec/rpc.rwalld/rwalld.c

/*
 * Copyright (c) 1993 Christopher G. Demetriou
 * 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.
 */

#ifndef lint
static char rcsid[] = "$Id: rwalld.c,v 1.2 1993/08/02 17:50:55 mycroft Exp $";
#endif /* not lint */

#include <unistd.h>
#include <sys/types.h>
#include <pwd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <signal.h>
#include <sys/wait.h>
#include <rpc/rpc.h>
#include <rpcsvc/rwall.h>

#ifdef OSF
#define WALL_CMD "/usr/sbin/wall"
#else
#define WALL_CMD "/usr/bin/wall -n"
#endif

void wallprog_1();
void possess();
void killkids();

int nodaemon = 0;
int from_inetd = 1;

main(argc, argv)
        int argc;
        char *argv[];
{
        SVCXPRT *transp;
        int s, salen;
        struct sockaddr_in sa;
        int sock = 0;
        int proto = 0;

        if (argc == 2 && !strcmp(argv[1], "-n"))
                nodaemon = 1;
        if (argc != 1 && !nodaemon) {
                printf("usage: %s [-n]\n", argv[0]);
                exit(1);
        }

        if (geteuid() == 0) {
                struct passwd *pep = getpwnam("nobody");
                if (pep)
                        setuid(pep->pw_uid);
                else
                        setuid(getuid());
        }

        /*
         * See if inetd started us
         */
        if (getsockname(0, (struct sockaddr *)&sa, &salen) < 0) {
                from_inetd = 0;
                sock = RPC_ANYSOCK;
                proto = IPPROTO_UDP;
        }

        if (!from_inetd) {
                if (!nodaemon)
                        possess();

                (void)pmap_unset(WALLPROG, WALLVERS);
                if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0) {
                        perror("socket");
                        exit(1);
                }
                bzero((char *)&sa, sizeof sa);
                if (bind(s, (struct sockaddr *)&sa, sizeof sa) < 0) {
                        perror("bind");
                        exit(1);
                }

                salen = sizeof sa;
                if (getsockname(s, (struct sockaddr *)&sa, &salen)) {
                        perror("getsockname");
                        exit(1);
                }

                pmap_set(WALLPROG, WALLVERS, IPPROTO_UDP, ntohs(sa.sin_port));
                if (dup2(s, 0) < 0) {
                        perror("dup2");
                        exit(1);
                }
                (void)pmap_unset(WALLPROG, WALLVERS);
        }

        (void)signal(SIGCHLD, killkids);

        transp = svcudp_create(sock);
        if (transp == NULL) {
                (void)fprintf(stderr, "cannot create udp service.\n");
                exit(1);
        }
        if (!svc_register(transp, WALLPROG, WALLVERS, wallprog_1, proto)) {
                (void)fprintf(stderr, "unable to register (WALLPROG, WALLVERS, udp).\n");
                exit(1);
        }
        svc_run();
        (void)fprintf(stderr, "svc_run returned\n");
        exit(1);

}

void possess()
{
        daemon(0, 0);
}

void killkids()
{
        while(wait4(-1, NULL, WNOHANG, NULL) > 0)
                ;
}

void *wallproc_wall_1(s)
        char **s;
{
        /* fork, popen wall with special option, and send the message */
        if (fork() == 0) {
                FILE *pfp;

                pfp = popen(WALL_CMD, "w");
                if (pfp != NULL) {
                        fprintf(pfp, "\007\007%s", *s);
                        pclose(pfp);
                        exit(0);
                }
        }
}

void
wallprog_1(rqstp, transp)
        struct svc_req *rqstp;
        SVCXPRT *transp;
{
        union {
                char *wallproc_wall_1_arg;
        } argument;
        char *result;
        bool_t (*xdr_argument)(), (*xdr_result)();
        char *(*local)();

        switch (rqstp->rq_proc) {
        case NULLPROC:
                (void)svc_sendreply(transp, xdr_void, (char *)NULL);
                goto leave;

        case WALLPROC_WALL:
                xdr_argument = xdr_wrapstring;
                xdr_result = xdr_void;
                local = (char *(*)()) wallproc_wall_1;
                break;

        default:
                svcerr_noproc(transp);
                goto leave;
        }
        bzero((char *)&argument, sizeof(argument));
        if (!svc_getargs(transp, xdr_argument, &argument)) {
                svcerr_decode(transp);
                goto leave;
        }
        result = (*local)(&argument, rqstp);
        if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
                svcerr_systemerr(transp);
        }
        if (!svc_freeargs(transp, xdr_argument, &argument)) {
                (void)fprintf(stderr, "unable to free arguments\n");
                exit(1);
        }
leave:
        if (from_inetd)
                exit(0);
}