rwalld.c revision 2341 
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 char rcsid[] = "$Id: rwalld.c,v 1.1 1993/09/16 00:36:44 jtc Exp $";
32#endif /* not lint */
33
34#include <unistd.h>
35#include <sys/types.h>
36#include <pwd.h>
37#include <stdio.h>
38#include <string.h>
39#include <errno.h>
40#include <sys/socket.h>
41#include <signal.h>
42#include <sys/wait.h>
43#include <rpc/rpc.h>
44#include <rpcsvc/rwall.h>
45
46#ifdef OSF
47#define WALL_CMD "/usr/sbin/wall"
48#else
49#define WALL_CMD "/usr/bin/wall -n"
50#endif
51
52void wallprog_1();
53void possess();
54void killkids();
55
56int nodaemon = 0;
57int from_inetd = 1;
58
59main(argc, argv)
60	int argc;
61	char *argv[];
62{
63	SVCXPRT *transp;
64	int s, salen;
65	struct sockaddr_in sa;
66        int sock = 0;
67        int proto = 0;
68
69	if (argc == 2 && !strcmp(argv[1], "-n"))
70		nodaemon = 1;
71	if (argc != 1 && !nodaemon) {
72		printf("usage: %s [-n]\n", argv[0]);
73		exit(1);
74	}
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        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                        perror("socket");
100                        exit(1);
101                }
102                bzero((char *)&sa, sizeof sa);
103                if (bind(s, (struct sockaddr *)&sa, sizeof sa) < 0) {
104                        perror("bind");
105                        exit(1);
106                }
107
108                salen = sizeof sa;
109                if (getsockname(s, (struct sockaddr *)&sa, &salen)) {
110                        perror("getsockname");
111                        exit(1);
112                }
113
114                pmap_set(WALLPROG, WALLVERS, IPPROTO_UDP, ntohs(sa.sin_port));
115                if (dup2(s, 0) < 0) {
116                        perror("dup2");
117                        exit(1);
118                }
119                (void)pmap_unset(WALLPROG, WALLVERS);
120        }
121
122	(void)signal(SIGCHLD, killkids);
123
124	transp = svcudp_create(sock);
125	if (transp == NULL) {
126		(void)fprintf(stderr, "cannot create udp service.\n");
127		exit(1);
128	}
129	if (!svc_register(transp, WALLPROG, WALLVERS, wallprog_1, proto)) {
130		(void)fprintf(stderr, "unable to register (WALLPROG, WALLVERS, udp).\n");
131		exit(1);
132	}
133	svc_run();
134	(void)fprintf(stderr, "svc_run returned\n");
135	exit(1);
136
137}
138
139void possess()
140{
141	daemon(0, 0);
142}
143
144void killkids()
145{
146	while(wait4(-1, NULL, WNOHANG, NULL) > 0)
147		;
148}
149
150void *wallproc_wall_1(s)
151	char **s;
152{
153	/* fork, popen wall with special option, and send the message */
154	if (fork() == 0) {
155		FILE *pfp;
156
157		pfp = popen(WALL_CMD, "w");
158		if (pfp != NULL) {
159			fprintf(pfp, "\007\007%s", *s);
160			pclose(pfp);
161			exit(0);
162		}
163	}
164}
165
166void
167wallprog_1(rqstp, transp)
168	struct svc_req *rqstp;
169	SVCXPRT *transp;
170{
171	union {
172		char *wallproc_wall_1_arg;
173	} argument;
174	char *result;
175	bool_t (*xdr_argument)(), (*xdr_result)();
176	char *(*local)();
177
178	switch (rqstp->rq_proc) {
179	case NULLPROC:
180		(void)svc_sendreply(transp, xdr_void, (char *)NULL);
181		goto leave;
182
183	case WALLPROC_WALL:
184		xdr_argument = xdr_wrapstring;
185		xdr_result = xdr_void;
186		local = (char *(*)()) wallproc_wall_1;
187		break;
188
189	default:
190		svcerr_noproc(transp);
191		goto leave;
192	}
193	bzero((char *)&argument, sizeof(argument));
194	if (!svc_getargs(transp, xdr_argument, &argument)) {
195		svcerr_decode(transp);
196		goto leave;
197	}
198	result = (*local)(&argument, rqstp);
199	if (result != NULL && !svc_sendreply(transp, xdr_result, result)) {
200		svcerr_systemerr(transp);
201	}
202	if (!svc_freeargs(transp, xdr_argument, &argument)) {
203		(void)fprintf(stderr, "unable to free arguments\n");
204		exit(1);
205	}
206leave:
207        if (from_inetd)
208                exit(0);
209}
210