xref: /freebsd/libexec/rpc.rwalld/rwalld.c (revision ae83180158c4c937f170e31eff311b18c0286a93)
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 
30 #ifndef lint
31 static const char rcsid[] =
32   "$FreeBSD$";
33 #endif /* not lint */
34 
35 #include <err.h>
36 #include <pwd.h>
37 #include <signal.h>
38 #include <stdio.h>
39 #include <stdlib.h>
40 #include <string.h>
41 #include <syslog.h>
42 #include <arpa/inet.h>
43 #include <rpc/rpc.h>
44 #include <rpcsvc/rwall.h>
45 #include <sys/socket.h>
46 #include <sys/types.h>
47 #include <sys/wait.h>
48 #include <unistd.h>
49 
50 #ifdef OSF
51 #define WALL_CMD "/usr/sbin/wall"
52 #else
53 #define WALL_CMD "/usr/bin/wall -n"
54 #endif
55 
56 void wallprog_1(struct svc_req *rqstp, SVCXPRT *transp);
57 void possess(void);
58 void killkids(int sig);
59 static void usage(void);
60 
61 int nodaemon = 0;
62 int from_inetd = 1;
63 
64 int
65 main(int argc, char *argv[])
66 {
67 	SVCXPRT *transp;
68 	int ok, salen;
69 	struct sockaddr_storage sa;
70 
71 	if (argc == 2 && !strcmp(argv[1], "-n"))
72 		nodaemon = 1;
73 	if (argc != 1 && !nodaemon)
74 		usage();
75 
76 	if (geteuid() == 0) {
77 		struct passwd *pep = getpwnam("nobody");
78 		if (pep)
79 			setuid(pep->pw_uid);
80 		else
81 			setuid(getuid());
82 	}
83 
84         /*
85          * See if inetd started us
86          */
87 	salen = sizeof(sa);
88         if (getsockname(0, (struct sockaddr *)&sa, &salen) < 0) {
89                 from_inetd = 0;
90         }
91 
92         if (!from_inetd) {
93                 if (!nodaemon)
94                         possess();
95 
96 		(void)rpcb_unset(WALLPROG, WALLVERS, NULL);
97         }
98 
99 	(void)signal(SIGCHLD, killkids);
100 
101 	openlog("rpc.rwalld", LOG_CONS|LOG_PID, LOG_DAEMON);
102 
103 	/* create and register the service */
104 	if (from_inetd) {
105 		transp = svc_tli_create(0, NULL, NULL, 0, 0);
106 		if (transp == NULL) {
107 			syslog(LOG_ERR, "couldn't create udp service.");
108 			exit(1);
109 		}
110 		ok = svc_reg(transp, WALLPROG, WALLVERS,
111 			     wallprog_1, NULL);
112 	} else
113 		ok = svc_create(wallprog_1,
114 				WALLPROG, WALLVERS, "udp");
115 	if (!ok) {
116 		syslog(LOG_ERR, "unable to register (WALLPROG, WALLVERS, %s)", (!from_inetd)?"udp":"(inetd)");
117 		exit(1);
118 	}
119 	svc_run();
120 	syslog(LOG_ERR, "svc_run returned");
121 	exit(1);
122 }
123 
124 static void
125 usage(void)
126 {
127 	fprintf(stderr, "usage: rpc.rwalld [-n]\n");
128 	exit(1);
129 }
130 
131 void
132 possess(void)
133 {
134 	daemon(0, 0);
135 }
136 
137 void
138 killkids(int sig)
139 {
140 	while(wait4(-1, NULL, WNOHANG, NULL) > 0)
141 		;
142 }
143 
144 void *
145 wallproc_wall_1_svc(wrapstring *s, struct svc_req *rqstp)
146 {
147 	static void		*dummy = NULL;
148 
149 	/* fork, popen wall with special option, and send the message */
150 	if (fork() == 0) {
151 		FILE *pfp;
152 
153 		pfp = popen(WALL_CMD, "w");
154 		if (pfp != NULL) {
155 			fprintf(pfp, "\007\007%s", *s);
156 			pclose(pfp);
157 			exit(0);
158 		}
159 	}
160 	return(&dummy);
161 }
162 
163 void
164 wallprog_1(struct svc_req *rqstp, SVCXPRT *transp)
165 {
166 	union {
167 		char *wallproc_wall_1_arg;
168 	} argument;
169 	char *result;
170 	bool_t (*xdr_argument)(), (*xdr_result)();
171 	char *(*local)();
172 
173 	switch (rqstp->rq_proc) {
174 	case NULLPROC:
175 		(void)svc_sendreply(transp, (xdrproc_t)xdr_void, NULL);
176 		goto leave;
177 
178 	case WALLPROC_WALL:
179 		xdr_argument = xdr_wrapstring;
180 		xdr_result = xdr_void;
181 		local = (char *(*)()) wallproc_wall_1_svc;
182 		break;
183 
184 	default:
185 		svcerr_noproc(transp);
186 		goto leave;
187 	}
188 	bzero(&argument, sizeof(argument));
189 	if (!svc_getargs(transp, (xdrproc_t)xdr_argument, &argument)) {
190 		svcerr_decode(transp);
191 		goto leave;
192 	}
193 	result = (*local)(&argument, rqstp);
194 	if (result != NULL &&
195 	    !svc_sendreply(transp, (xdrproc_t)xdr_result, result)) {
196 		svcerr_systemerr(transp);
197 	}
198 	if (!svc_freeargs(transp, (xdrproc_t)xdr_argument, &argument)) {
199 		syslog(LOG_ERR, "unable to free arguments");
200 		exit(1);
201 	}
202 leave:
203         if (from_inetd)
204                 exit(0);
205 }
206