1/*	$OpenBSD: ypldap_dns.c,v 1.8 2015/01/16 06:40:22 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/param.h>
21#include <sys/socket.h>
22#include <sys/stat.h>
23#include <sys/time.h>
24#include <sys/tree.h>
25#include <sys/queue.h>
26
27#include <netinet/in.h>
28#include <arpa/nameser.h>
29
30#include <netdb.h>
31#include <pwd.h>
32#include <errno.h>
33#include <event.h>
34#include <resolv.h>
35#include <poll.h>
36#include <signal.h>
37#include <stdlib.h>
38#include <string.h>
39#include <unistd.h>
40#include <limits.h>
41
42#include "ypldap.h"
43
44volatile sig_atomic_t	 quit_dns = 0;
45struct imsgev		*iev_dns;
46
47void	dns_dispatch_imsg(int, short, void *);
48void	dns_sig_handler(int, short, void *);
49void	dns_shutdown(void);
50int	host_dns(const char *, struct ypldap_addr_list *);
51
52void
53dns_sig_handler(int sig, short event, void *p)
54{
55	switch (sig) {
56	case SIGINT:
57	case SIGTERM:
58		dns_shutdown();
59		break;
60	default:
61		fatalx("unexpected signal");
62	}
63}
64
65void
66dns_shutdown(void)
67{
68	log_info("dns engine exiting");
69	_exit(0);
70}
71
72pid_t
73ypldap_dns(int pipe_ntp[2], struct passwd *pw)
74{
75	pid_t			 pid;
76	struct event	 ev_sigint;
77	struct event	 ev_sigterm;
78	struct event	 ev_sighup;
79	struct env	 env;
80
81	switch (pid = fork()) {
82	case -1:
83		fatal("cannot fork");
84		break;
85	case 0:
86		break;
87	default:
88		return (pid);
89	}
90
91	setproctitle("dns engine");
92	close(pipe_ntp[0]);
93
94	if (setgroups(1, &pw->pw_gid) ||
95	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
96	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
97		fatal("can't drop privileges");
98	endservent();
99
100	event_init();
101	signal_set(&ev_sigint, SIGINT, dns_sig_handler, NULL);
102	signal_set(&ev_sigterm, SIGTERM, dns_sig_handler, NULL);
103	signal_set(&ev_sighup, SIGHUP, dns_sig_handler, NULL);
104	signal_add(&ev_sigint, NULL);
105	signal_add(&ev_sigterm, NULL);
106	signal_add(&ev_sighup, NULL);
107
108	if ((env.sc_iev = calloc(1, sizeof(*env.sc_iev))) == NULL)
109		fatal(NULL);
110
111	env.sc_iev->events = EV_READ;
112	env.sc_iev->data = &env;
113	imsg_init(&env.sc_iev->ibuf, pipe_ntp[1]);
114	env.sc_iev->handler = dns_dispatch_imsg;
115	event_set(&env.sc_iev->ev, env.sc_iev->ibuf.fd, env.sc_iev->events,
116	    env.sc_iev->handler, &env);
117	event_add(&env.sc_iev->ev, NULL);
118
119	event_dispatch();
120	dns_shutdown();
121
122	return (0);
123}
124
125void
126dns_dispatch_imsg(int fd, short events, void *p)
127{
128	struct imsg		 imsg;
129	int			 n, cnt;
130	char			*name;
131	struct ypldap_addr_list	hn = TAILQ_HEAD_INITIALIZER(hn);
132	struct ypldap_addr	*h;
133	struct ibuf		*buf;
134	struct env		*env = p;
135	struct imsgev		*iev = env->sc_iev;
136	struct imsgbuf		*ibuf = &iev->ibuf;
137	int			 shut = 0;
138
139	if ((events & (EV_READ | EV_WRITE)) == 0)
140		fatalx("unknown event");
141
142	if (events & EV_READ) {
143		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
144			fatal("imsg_read error");
145		if (n == 0)
146			shut = 1;
147	}
148	if (events & EV_WRITE) {
149		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
150			fatal("msgbuf_write");
151		if (n == 0)
152			shut = 1;
153		goto done;
154	}
155
156	for (;;) {
157		if ((n = imsg_get(ibuf, &imsg)) == -1)
158			fatal("client_dispatch_imsg: imsg_get error");
159		if (n == 0)
160			break;
161
162		switch (imsg.hdr.type) {
163		case IMSG_HOST_DNS:
164			name = imsg.data;
165			if (imsg.hdr.len < 1 + IMSG_HEADER_SIZE)
166				fatalx("invalid IMSG_HOST_DNS received");
167			imsg.hdr.len -= 1 + IMSG_HEADER_SIZE;
168			if (name[imsg.hdr.len] != '\0' ||
169			    strlen(name) != imsg.hdr.len)
170				fatalx("invalid IMSG_HOST_DNS received");
171			if ((cnt = host_dns(name, &hn)) == -1)
172				break;
173			buf = imsg_create(ibuf, IMSG_HOST_DNS,
174			    imsg.hdr.peerid, 0,
175			    cnt * sizeof(struct sockaddr_storage));
176			if (buf == NULL)
177				break;
178			if (cnt > 0) {
179				while(!TAILQ_EMPTY(&hn)) {
180					h = TAILQ_FIRST(&hn);
181					TAILQ_REMOVE(&hn, h, next);
182					imsg_add(buf, &h->ss, sizeof(h->ss));
183					free(h);
184				}
185			}
186
187			imsg_close(ibuf, buf);
188			break;
189		default:
190			break;
191		}
192		imsg_free(&imsg);
193	}
194
195done:
196	if (!shut)
197		imsg_event_add(iev);
198	else {
199		/* this pipe is dead, so remove the event handler */
200		event_del(&iev->ev);
201		event_loopexit(NULL);
202	}
203}
204
205int
206host_dns(const char *s, struct ypldap_addr_list *hn)
207{
208	struct addrinfo		 hints, *res0, *res;
209	int			 error, cnt = 0;
210	struct sockaddr_in	*sa_in;
211	struct sockaddr_in6	*sa_in6;
212	struct ypldap_addr	*h;
213
214	memset(&hints, 0, sizeof(hints));
215	hints.ai_family = PF_UNSPEC;
216	hints.ai_socktype = SOCK_DGRAM; /* DUMMY */
217	error = getaddrinfo(s, NULL, &hints, &res0);
218	if (error == EAI_AGAIN || error == EAI_NONAME)
219			return (0);
220	if (error) {
221		log_warnx("could not parse \"%s\": %s", s,
222		    gai_strerror(error));
223		return (-1);
224	}
225
226	for (res = res0; res && cnt < MAX_SERVERS_DNS; res = res->ai_next) {
227		if (res->ai_family != AF_INET &&
228		    res->ai_family != AF_INET6)
229			continue;
230		if ((h = calloc(1, sizeof(struct ypldap_addr))) == NULL)
231			fatal(NULL);
232		h->ss.ss_family = res->ai_family;
233		if (res->ai_family == AF_INET) {
234			sa_in = (struct sockaddr_in *)&h->ss;
235			sa_in->sin_len = sizeof(struct sockaddr_in);
236			sa_in->sin_addr.s_addr = ((struct sockaddr_in *)
237			    res->ai_addr)->sin_addr.s_addr;
238		} else {
239			sa_in6 = (struct sockaddr_in6 *)&h->ss;
240			sa_in6->sin6_len = sizeof(struct sockaddr_in6);
241			memcpy(&sa_in6->sin6_addr, &((struct sockaddr_in6 *)
242			    res->ai_addr)->sin6_addr, sizeof(struct in6_addr));
243		}
244
245		TAILQ_INSERT_HEAD(hn, h, next);
246		cnt++;
247	}
248	freeaddrinfo(res0);
249	return (cnt);
250}
251