rwalld.c revision 90336 
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
31static const char rcsid[] =
32  "$FreeBSD: head/libexec/rpc.rwalld/rwalld.c 90336 2002-02-07 05:24:53Z imp $";
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 <rpc/rpc.h>
43#include <rpc/pmap_clnt.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
56void wallprog_1(struct svc_req *rqstp, SVCXPRT *transp);
57void possess(void);
58void killkids(int sig);
59static void usage(void);
60
61int nodaemon = 0;
62int from_inetd = 1;
63
64int
65main(int argc, 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
135static void
136usage(void)
137{
138	fprintf(stderr, "usage: rpc.rwalld [-n]\n");
139	exit(1);
140}
141
142void
143possess(void)
144{
145	daemon(0, 0);
146}
147
148void
149killkids(int sig)
150{
151	while(wait4(-1, NULL, WNOHANG, NULL) > 0)
152		;
153}
154
155void *
156wallproc_wall_1_svc(wrapstring *s, struct svc_req *rqstp)
157{
158	static void		*dummy = NULL;
159
160	/* fork, popen wall with special option, and send the message */
161	if (fork() == 0) {
162		FILE *pfp;
163
164		pfp = popen(WALL_CMD, "w");
165		if (pfp != NULL) {
166			fprintf(pfp, "\007\007%s", *s);
167			pclose(pfp);
168			exit(0);
169		}
170	}
171	return(&dummy);
172}
173
174void
175wallprog_1(struct svc_req *rqstp, SVCXPRT *transp)
176{
177	union {
178		char *wallproc_wall_1_arg;
179	} argument;
180	char *result;
181	bool_t (*xdr_argument)(), (*xdr_result)();
182	char *(*local)();
183
184	switch (rqstp->rq_proc) {
185	case NULLPROC:
186		(void)svc_sendreply(transp, xdr_void, (char *)NULL);
187		goto leave;
188
189	case WALLPROC_WALL:
190		xdr_argument = xdr_wrapstring;
191		xdr_result = xdr_void;
192		local = (char *(*)()) wallproc_wall_1_svc;
193		break;
194
195	default:
196		svcerr_noproc(transp);
197		goto leave;
198	}
199	bzero((char *)&argument, sizeof(argument));
200	if (!svc_getargs(transp, xdr_argument, (caddr_t)&argument)) {
201		svcerr_decode(transp);
202		goto leave;
203	}
204	result = (*local)(&argument, rqstp);
205	if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
206		svcerr_systemerr(transp);
207	}
208	if (!svc_freeargs(transp, xdr_argument, (caddr_t)&argument)) {
209		syslog(LOG_ERR, "unable to free arguments");
210		exit(1);
211	}
212leave:
213        if (from_inetd)
214                exit(0);
215}
216