libexec/rpc.rwalld/rwalld.c

   1 /*
   2  * Copyright (c) 1993 Christopher G. Demetriou
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote
  14  *    products derived from this software without specific prior written
  15  *    permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
  18  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  21  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD: src/libexec/rpc.rwalld/rwalld.c,v 1.8 1999/08/28 00:09:57 peter Exp $
  30  * $DragonFly: src/libexec/rpc.rwalld/rwalld.c,v 1.3 2003/11/14 03:54:31 dillon Exp $
  31  */
  32
  33 #include <err.h>
  34 #include <pwd.h>
  35 #include <signal.h>
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <string.h>
  39 #include <syslog.h>
  40 #include <rpc/rpc.h>
  41 #include <rpc/pmap_clnt.h>
  42 #include <rpcsvc/rwall.h>
  43 #include <sys/socket.h>
  44 #include <sys/types.h>
  45 #include <sys/wait.h>
  46 #include <unistd.h>
  47
  48 #ifdef OSF
  49 #define WALL_CMD "/usr/sbin/wall"
  50 #else
  51 #define WALL_CMD "/usr/bin/wall -n"
  52 #endif
  53
  54 void wallprog_1();
  55 void possess();
  56 void killkids();
  57 static void usage (void);
  58
  59 int nodaemon = 0;
  60 int from_inetd = 1;
  61
  62 int
  63 main(argc, argv)
  64         int argc;
  65         char *argv[];
  66 {
  67         SVCXPRT *transp;
  68         int s, salen;
  69         struct sockaddr_in sa;
  70         int sock = 0;
  71         int proto = 0;
  72
  73         if (argc == 2 && !strcmp(argv[1], "-n"))
  74                 nodaemon = 1;
  75         if (argc != 1 && !nodaemon)
  76                 usage();
  77
  78         if (geteuid() == 0) {
  79                 struct passwd *pep = getpwnam("nobody");
  80                 if (pep)
  81                         setuid(pep->pw_uid);
  82                 else
  83                         setuid(getuid());
  84         }
  85
  86         /*
  87          * See if inetd started us
  88          */
  89         salen = sizeof(sa);
  90         if (getsockname(0, (struct sockaddr *)&sa, &salen) < 0) {
  91                 from_inetd = 0;
  92                 sock = RPC_ANYSOCK;
  93                 proto = IPPROTO_UDP;
  94         }
  95
  96         if (!from_inetd) {
  97                 if (!nodaemon)
  98                         possess();
  99
 100                 (void)pmap_unset(WALLPROG, WALLVERS);
 101                 if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
 102                         err(1, "socket");
 103                 bzero((char *)&sa, sizeof sa);
 104                 if (bind(s, (struct sockaddr *)&sa, sizeof sa) < 0)
 105                         err(1, "bind");
 106
 107                 salen = sizeof sa;
 108                 if (getsockname(s, (struct sockaddr *)&sa, &salen))
 109                         err(1, "getsockname");
 110
 111                 pmap_set(WALLPROG, WALLVERS, IPPROTO_UDP, ntohs(sa.sin_port));
 112                 if (dup2(s, 0) < 0)
 113                         err(1, "dup2");
 114                 (void)pmap_unset(WALLPROG, WALLVERS);
 115         }
 116
 117         (void)signal(SIGCHLD, killkids);
 118
 119         openlog("rpc.rwalld", LOG_CONS|LOG_PID, LOG_DAEMON);
 120
 121         transp = svcudp_create(sock);
 122         if (transp == NULL) {
 123                 syslog(LOG_ERR, "cannot create udp service");
 124                 exit(1);
 125         }
 126         if (!svc_register(transp, WALLPROG, WALLVERS, wallprog_1, proto)) {
 127                 syslog(LOG_ERR, "unable to register (WALLPROG, WALLVERS, %s)", proto?"udp":"(inetd)");
 128                 exit(1);
 129         }
 130         svc_run();
 131         syslog(LOG_ERR, "svc_run returned");
 132         exit(1);
 133 }
 134
 135 static void
 136 usage()
 137 {
 138         fprintf(stderr, "usage: rpc.rwalld [-n]\n");
 139         exit(1);
 140 }
 141
 142 void possess()
 143 {
 144         daemon(0, 0);
 145 }
 146
 147 void killkids()
 148 {
 149         while(wait4(-1, NULL, WNOHANG, NULL) > 0)
 150                 ;
 151 }
 152
 153 void *wallproc_wall_1_svc(s, rqstp)
 154         wrapstring              *s;
 155         struct svc_req          *rqstp;
 156 {
 157         static void             *dummy = NULL;
 158
 159         /* fork, popen wall with special option, and send the message */
 160         if (fork() == 0) {
 161                 FILE *pfp;
 162
 163                 pfp = popen(WALL_CMD, "w");
 164                 if (pfp != NULL) {
 165                         fprintf(pfp, "\007\007%s", *s);
 166                         pclose(pfp);
 167                         exit(0);
 168                 }
 169         }
 170         return(&dummy);
 171 }
 172
 173 void
 174 wallprog_1(rqstp, transp)
 175         struct svc_req *rqstp;
 176         SVCXPRT *transp;
 177 {
 178         union {
 179                 char *wallproc_wall_1_arg;
 180         } argument;
 181         char *result;
 182         bool_t (*xdr_argument)(), (*xdr_result)();
 183         char *(*local)();
 184
 185         switch (rqstp->rq_proc) {
 186         case NULLPROC:
 187                 (void)svc_sendreply(transp, xdr_void, (char *)NULL);
 188                 goto leave;
 189
 190         case WALLPROC_WALL:
 191                 xdr_argument = xdr_wrapstring;
 192                 xdr_result = xdr_void;
 193                 local = (char *(*)()) wallproc_wall_1_svc;
 194                 break;
 195
 196         default:
 197                 svcerr_noproc(transp);
 198                 goto leave;
 199         }
 200         bzero((char *)&argument, sizeof(argument));
 201         if (!svc_getargs(transp, xdr_argument, (caddr_t)&argument)) {
 202                 svcerr_decode(transp);
 203                 goto leave;
 204         }
 205         result = (*local)(&argument, rqstp);
 206         if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
 207                 svcerr_systemerr(transp);
 208         }
 209         if (!svc_freeargs(transp, xdr_argument, (caddr_t)&argument)) {
 210                 syslog(LOG_ERR, "unable to free arguments");
 211                 exit(1);
 212         }
 213 leave:
 214         if (from_inetd)
 215                 exit(0);
 216 }