xref: /openbsd/usr.sbin/ypldap/ypldap_dns.c (revision d89ec533)
1 /*	$OpenBSD: ypldap_dns.c,v 1.14 2021/10/09 18:43:50 deraadt Exp $ */
2 
3 /*
4  * Copyright (c) 2003-2008 Henning Brauer <henning@openbsd.org>
5  *
6  * Permission to use, copy, modify, and distribute this software for any
7  * purpose with or without fee is hereby granted, provided that the above
8  * copyright notice and this permission notice appear in all copies.
9  *
10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14  * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
15  * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
16  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include <sys/types.h>
20 #include <sys/socket.h>
21 #include <sys/stat.h>
22 #include <sys/time.h>
23 #include <sys/tree.h>
24 #include <sys/queue.h>
25 
26 #include <netinet/in.h>
27 
28 #include <netdb.h>
29 #include <pwd.h>
30 #include <errno.h>
31 #include <event.h>
32 #include <resolv.h>
33 #include <poll.h>
34 #include <signal.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38 #include <limits.h>
39 
40 #include "ypldap.h"
41 
42 volatile sig_atomic_t	 quit_dns = 0;
43 struct imsgev		*iev_dns;
44 
45 void	dns_dispatch_imsg(int, short, void *);
46 void	dns_sig_handler(int, short, void *);
47 void	dns_shutdown(void);
48 int	host_dns(const char *, struct ypldap_addr_list *);
49 
50 void
51 dns_sig_handler(int sig, short event, void *p)
52 {
53 	switch (sig) {
54 	case SIGINT:
55 	case SIGTERM:
56 		dns_shutdown();
57 		break;
58 	default:
59 		fatalx("unexpected signal");
60 	}
61 }
62 
63 void
64 dns_shutdown(void)
65 {
66 	log_info("dns engine exiting");
67 	_exit(0);
68 }
69 
70 pid_t
71 ypldap_dns(int pipe_ntp[2], struct passwd *pw)
72 {
73 	pid_t			 pid;
74 	struct event	 ev_sigint;
75 	struct event	 ev_sigterm;
76 	struct event	 ev_sighup;
77 	struct env	 env;
78 
79 	switch (pid = fork()) {
80 	case -1:
81 		fatal("cannot fork");
82 		break;
83 	case 0:
84 		break;
85 	default:
86 		return (pid);
87 	}
88 
89 	setproctitle("dns engine");
90 	close(pipe_ntp[0]);
91 
92 	if (setgroups(1, &pw->pw_gid) ||
93 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
94 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
95 		fatal("can't drop privileges");
96 	endservent();
97 
98 	if (pledge("stdio dns", NULL) == -1)
99 		fatal("pledge");
100 
101 	event_init();
102 	signal_set(&ev_sigint, SIGINT, dns_sig_handler, NULL);
103 	signal_set(&ev_sigterm, SIGTERM, dns_sig_handler, NULL);
104 	signal_set(&ev_sighup, SIGHUP, dns_sig_handler, NULL);
105 	signal_add(&ev_sigint, NULL);
106 	signal_add(&ev_sigterm, NULL);
107 	signal_add(&ev_sighup, NULL);
108 
109 	if ((env.sc_iev = calloc(1, sizeof(*env.sc_iev))) == NULL)
110 		fatal(NULL);
111 
112 	env.sc_iev->events = EV_READ;
113 	env.sc_iev->data = &env;
114 	imsg_init(&env.sc_iev->ibuf, pipe_ntp[1]);
115 	env.sc_iev->handler = dns_dispatch_imsg;
116 	event_set(&env.sc_iev->ev, env.sc_iev->ibuf.fd, env.sc_iev->events,
117 	    env.sc_iev->handler, &env);
118 	event_add(&env.sc_iev->ev, NULL);
119 
120 	event_dispatch();
121 	dns_shutdown();
122 
123 	return (0);
124 }
125 
126 void
127 dns_dispatch_imsg(int fd, short events, void *p)
128 {
129 	struct imsg		 imsg;
130 	int			 n, cnt;
131 	char			*name;
132 	struct ypldap_addr_list	 hn = TAILQ_HEAD_INITIALIZER(hn);
133 	struct ypldap_addr	*h;
134 	struct ibuf		*buf;
135 	struct env		*env = p;
136 	struct imsgev		*iev = env->sc_iev;
137 	struct imsgbuf		*ibuf = &iev->ibuf;
138 	int			 shut = 0;
139 	size_t			 len;
140 
141 	if ((events & (EV_READ | EV_WRITE)) == 0)
142 		fatalx("unknown event");
143 
144 	if (events & EV_READ) {
145 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
146 			fatal("imsg_read error");
147 		if (n == 0)
148 			shut = 1;
149 	}
150 	if (events & EV_WRITE) {
151 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
152 			fatal("msgbuf_write");
153 		if (n == 0)
154 			shut = 1;
155 		goto done;
156 	}
157 
158 	for (;;) {
159 		if ((n = imsg_get(ibuf, &imsg)) == -1)
160 			fatal("client_dispatch_imsg: imsg_get error");
161 		if (n == 0)
162 			break;
163 
164 		switch (imsg.hdr.type) {
165 		case IMSG_HOST_DNS:
166 			name = imsg.data;
167 			if (imsg.hdr.len < 1 + IMSG_HEADER_SIZE)
168 				fatalx("invalid IMSG_HOST_DNS received");
169 			len = imsg.hdr.len - 1 - IMSG_HEADER_SIZE;
170 			if (name[len] != '\0' ||
171 			    strlen(name) != len)
172 				fatalx("invalid IMSG_HOST_DNS received");
173 			if ((cnt = host_dns(name, &hn)) == -1)
174 				break;
175 			buf = imsg_create(ibuf, IMSG_HOST_DNS,
176 			    imsg.hdr.peerid, 0,
177 			    cnt * sizeof(struct sockaddr_storage));
178 			if (buf == NULL)
179 				break;
180 			if (cnt > 0) {
181 				while (!TAILQ_EMPTY(&hn)) {
182 					h = TAILQ_FIRST(&hn);
183 					TAILQ_REMOVE(&hn, h, next);
184 					imsg_add(buf, &h->ss, sizeof(h->ss));
185 					free(h);
186 				}
187 			}
188 
189 			imsg_close(ibuf, buf);
190 			break;
191 		default:
192 			break;
193 		}
194 		imsg_free(&imsg);
195 	}
196 
197 done:
198 	if (!shut)
199 		imsg_event_add(iev);
200 	else {
201 		/* this pipe is dead, so remove the event handler */
202 		event_del(&iev->ev);
203 		event_loopexit(NULL);
204 	}
205 }
206 
207 int
208 host_dns(const char *s, struct ypldap_addr_list *hn)
209 {
210 	struct addrinfo		 hints, *res0, *res;
211 	int			 error, cnt = 0;
212 	struct sockaddr_in	*sa_in;
213 	struct sockaddr_in6	*sa_in6;
214 	struct ypldap_addr	*h;
215 
216 	memset(&hints, 0, sizeof(hints));
217 	hints.ai_family = PF_UNSPEC;
218 	hints.ai_socktype = SOCK_DGRAM; /* DUMMY */
219 	error = getaddrinfo(s, NULL, &hints, &res0);
220 	if (error == EAI_AGAIN || error == EAI_NODATA || error == EAI_NONAME)
221 			return (0);
222 	if (error) {
223 		log_warnx("could not parse \"%s\": %s", s,
224 		    gai_strerror(error));
225 		return (-1);
226 	}
227 
228 	for (res = res0; res && cnt < MAX_SERVERS_DNS; res = res->ai_next) {
229 		if (res->ai_family != AF_INET &&
230 		    res->ai_family != AF_INET6)
231 			continue;
232 		if ((h = calloc(1, sizeof(struct ypldap_addr))) == NULL)
233 			fatal(NULL);
234 		h->ss.ss_family = res->ai_family;
235 		if (res->ai_family == AF_INET) {
236 			sa_in = (struct sockaddr_in *)&h->ss;
237 			sa_in->sin_len = sizeof(struct sockaddr_in);
238 			sa_in->sin_addr.s_addr = ((struct sockaddr_in *)
239 			    res->ai_addr)->sin_addr.s_addr;
240 		} else {
241 			sa_in6 = (struct sockaddr_in6 *)&h->ss;
242 			sa_in6->sin6_len = sizeof(struct sockaddr_in6);
243 			memcpy(&sa_in6->sin6_addr, &((struct sockaddr_in6 *)
244 			    res->ai_addr)->sin6_addr, sizeof(struct in6_addr));
245 		}
246 
247 		TAILQ_INSERT_HEAD(hn, h, next);
248 		cnt++;
249 	}
250 	freeaddrinfo(res0);
251 	return (cnt);
252 }
253