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  */
  31
  32 #include <err.h>
  33 #include <pwd.h>
  34 #include <signal.h>
  35 #include <stdio.h>
  36 #include <stdlib.h>
  37 #include <string.h>
  38 #include <syslog.h>
  39 #include <rpc/rpc.h>
  40 #include <rpc/pmap_clnt.h>
  41 #include <rpcsvc/rwall.h>
  42 #include <sys/socket.h>
  43 #include <sys/types.h>
  44 #include <sys/wait.h>
  45 #include <unistd.h>
  46
  47 #ifdef OSF
  48 #define WALL_CMD "/usr/sbin/wall"
  49 #else
  50 #define WALL_CMD "/usr/bin/wall -n"
  51 #endif
  52
  53 void wallprog_1();
  54 void possess();
  55 void killkids();
  56 static void usage (void);
  57
  58 int nodaemon = 0;
  59 int from_inetd = 1;
  60
  61 int
  62 main(int argc, char *argv[])
  63 {
  64         SVCXPRT *transp;
  65         int s, salen;
  66         struct sockaddr_in sa;
  67         int sock = 0;
  68         int proto = 0;
  69
  70         if (argc == 2 && !strcmp(argv[1], "-n"))
  71                 nodaemon = 1;
  72         if (argc != 1 && !nodaemon)
  73                 usage();
  74
  75         if (geteuid() == 0) {
  76                 struct passwd *pep = getpwnam("nobody");
  77                 if (pep)
  78                         setuid(pep->pw_uid);
  79                 else
  80                         setuid(getuid());
  81         }
  82
  83         /*
  84          * See if inetd started us
  85          */
  86         salen = sizeof(sa);
  87         if (getsockname(0, (struct sockaddr *)&sa, &salen) < 0) {
  88                 from_inetd = 0;
  89                 sock = RPC_ANYSOCK;
  90                 proto = IPPROTO_UDP;
  91         }
  92
  93         if (!from_inetd) {
  94                 if (!nodaemon)
  95                         possess();
  96
  97                 (void)pmap_unset(WALLPROG, WALLVERS);
  98                 if ((s = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
  99                         err(1, "socket");
 100                 bzero((char *)&sa, sizeof sa);
 101                 if (bind(s, (struct sockaddr *)&sa, sizeof sa) < 0)
 102                         err(1, "bind");
 103
 104                 salen = sizeof sa;
 105                 if (getsockname(s, (struct sockaddr *)&sa, &salen))
 106                         err(1, "getsockname");
 107
 108                 pmap_set(WALLPROG, WALLVERS, IPPROTO_UDP, ntohs(sa.sin_port));
 109                 if (dup2(s, 0) < 0)
 110                         err(1, "dup2");
 111                 (void)pmap_unset(WALLPROG, WALLVERS);
 112         }
 113
 114         (void)signal(SIGCHLD, killkids);
 115
 116         openlog("rpc.rwalld", LOG_CONS|LOG_PID, LOG_DAEMON);
 117
 118         transp = svcudp_create(sock);
 119         if (transp == NULL) {
 120                 syslog(LOG_ERR, "cannot create udp service");
 121                 exit(1);
 122         }
 123         if (!svc_register(transp, WALLPROG, WALLVERS, wallprog_1, proto)) {
 124                 syslog(LOG_ERR, "unable to register (WALLPROG, WALLVERS, %s)", proto?"udp":"(inetd)");
 125                 exit(1);
 126         }
 127         svc_run();
 128         syslog(LOG_ERR, "svc_run returned");
 129         exit(1);
 130 }
 131
 132 static void
 133 usage(void)
 134 {
 135         fprintf(stderr, "usage: rpc.rwalld [-n]\n");
 136         exit(1);
 137 }
 138
 139 void
 140 possess(void)
 141 {
 142         daemon(0, 0);
 143 }
 144
 145 void
 146 killkids(void)
 147 {
 148         while(wait4(-1, NULL, WNOHANG, NULL) > 0)
 149                 ;
 150 }
 151
 152 void *
 153 wallproc_wall_1_svc(wrapstring *s, struct svc_req *rqstp)
 154 {
 155         static void             *dummy = NULL;
 156
 157         /* fork, popen wall with special option, and send the message */
 158         if (fork() == 0) {
 159                 FILE *pfp;
 160
 161                 pfp = popen(WALL_CMD, "w");
 162                 if (pfp != NULL) {
 163                         fprintf(pfp, "\007\007%s", *s);
 164                         pclose(pfp);
 165                         exit(0);
 166                 }
 167         }
 168         return(&dummy);
 169 }
 170
 171 void
 172 wallprog_1(struct svc_req *rqstp, SVCXPRT *transp)
 173 {
 174         union {
 175                 char *wallproc_wall_1_arg;
 176         } argument;
 177         char *result;
 178         bool_t (*xdr_argument)(), (*xdr_result)();
 179         char *(*local)();
 180
 181         switch (rqstp->rq_proc) {
 182         case NULLPROC:
 183                 (void)svc_sendreply(transp, (xdrproc_t)xdr_void, NULL);
 184                 goto leave;
 185
 186         case WALLPROC_WALL:
 187                 xdr_argument = xdr_wrapstring;
 188                 xdr_result = xdr_void;
 189                 local = (char *(*)()) wallproc_wall_1_svc;
 190                 break;
 191
 192         default:
 193                 svcerr_noproc(transp);
 194                 goto leave;
 195         }
 196         bzero((char *)&argument, sizeof(argument));
 197         if (!svc_getargs(transp, (xdrproc_t)xdr_argument, (caddr_t)&argument)) {
 198                 svcerr_decode(transp);
 199                 goto leave;
 200         }
 201         result = (*local)(&argument, rqstp);
 202         if (result != NULL &&
 203             !svc_sendreply(transp, (xdrproc_t)xdr_result, result)) {
 204                 svcerr_systemerr(transp);
 205         }
 206         if (!svc_freeargs(transp, (xdrproc_t)xdr_argument, (caddr_t)&argument)) {
 207                 syslog(LOG_ERR, "unable to free arguments");
 208                 exit(1);
 209         }
 210 leave:
 211         if (from_inetd)
 212                 exit(0);
 213 }