1 /*	$OpenBSD: control.c,v 1.4 2021/08/01 09:07:03 florian Exp $	*/
2 
3 /*
4  * Copyright (c) 2003, 2004 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 USE, DATA OR PROFITS, WHETHER IN AN
15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17  */
18 
19 #include "compat.h"
20 
21 #include <sys/types.h>
22 #include <sys/stat.h>
23 #include <sys/socket.h>
24 #include <sys/uio.h>
25 #include <sys/un.h>
26 
27 #include <errno.h>
28 #include <stdlib.h>
29 #include <string.h>
30 #include <unistd.h>
31 
32 #include "control.h"
33 #include "ev.h"
34 #include "imsgev.h"
35 #include "minibuffer.h"
36 #include "telescope.h"
37 #include "utils.h"
38 #include "ui.h"
39 
40 #define	CONTROL_BACKLOG	5
41 
42 struct {
43 	unsigned long	timeout;
44 	int		fd;
45 } control_state = {.fd = -1};
46 
47 struct ctl_conn {
48 	TAILQ_ENTRY(ctl_conn)	entry;
49 	struct imsgev		iev;
50 };
51 
52 struct ctl_conn	*control_connbyfd(int);
53 struct ctl_conn	*control_connbypid(pid_t);
54 void		 control_close(int);
55 
56 TAILQ_HEAD(ctl_conns, ctl_conn) ctl_conns = TAILQ_HEAD_INITIALIZER(ctl_conns);
57 
58 int
59 control_init(char *path)
60 {
61 	struct sockaddr_un	 sun;
62 	int			 fd;
63 	mode_t			 old_umask;
64 
65 	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
66 		warn("%s: socket", __func__);
67 		return (-1);
68 	}
69 
70 	if (!mark_nonblock_cloexec(fd)) {
71 		close(fd);
72 		return (-1);
73 	}
74 
75 	memset(&sun, 0, sizeof(sun));
76 	sun.sun_family = AF_UNIX;
77 	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
78 
79 	if (unlink(path) == -1)
80 		if (errno != ENOENT) {
81 			warn("%s: unlink %s", __func__, path);
82 			close(fd);
83 			return (-1);
84 		}
85 
86 	old_umask = umask(S_IXUSR|S_IXGRP|S_IWOTH|S_IROTH|S_IXOTH);
87 	if (bind(fd, (struct sockaddr *)&sun, sizeof(sun)) == -1) {
88 		warn("%s: bind: %s", __func__, path);
89 		close(fd);
90 		umask(old_umask);
91 		return (-1);
92 	}
93 	umask(old_umask);
94 
95 	if (chmod(path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP) == -1) {
96 		warn("%s: chmod", __func__);
97 		close(fd);
98 		(void)unlink(path);
99 		return (-1);
100 	}
101 
102 	return (fd);
103 }
104 
105 int
106 control_listen(int fd)
107 {
108 	control_state.fd = fd;
109 	if (listen(control_state.fd, CONTROL_BACKLOG) == -1) {
110 		warn("%s: listen", __func__);
111 		return (-1);
112 	}
113 
114 	ev_add(control_state.fd, EV_READ, control_accept, NULL);
115 	return (0);
116 }
117 
118 void
119 control_accept(int listenfd, int event, void *bula)
120 {
121 	int			 connfd;
122 	socklen_t		 len;
123 	struct sockaddr_un	 sun;
124 	struct ctl_conn		*c;
125 
126 	ev_add(control_state.fd, EV_READ, control_accept, NULL);
127 	if ((event & EV_TIMEOUT))
128 		return;
129 
130 	len = sizeof(sun);
131 	if ((connfd = accept(listenfd, (struct sockaddr *)&sun, &len)) == -1) {
132 		/*
133 		 * Pause accept if we are out of file descriptors, or
134 		 * ev will haunt us here too.
135 		 */
136 		if (errno == ENFILE || errno == EMFILE) {
137 			struct timeval evtpause = { 1, 0 };
138 
139 			ev_del(control_state.fd);
140 			control_state.timeout = ev_timer(&evtpause,
141 			    control_accept, NULL);
142 		} else if (errno != EWOULDBLOCK && errno != EINTR &&
143 		    errno != ECONNABORTED)
144 			message("%s: accept4: %s", __func__, strerror(errno));
145 		return;
146 	}
147 
148 	if (!mark_nonblock_cloexec(connfd)) {
149 		message("%s: mark_nonblock_cloexec: %s", __func__,
150 		    strerror(errno));
151 		close(connfd);
152 		return;
153 	}
154 
155 	if ((c = calloc(1, sizeof(struct ctl_conn))) == NULL) {
156 		message("%s: calloc: %s", __func__, strerror(errno));
157 		close(connfd);
158 		return;
159 	}
160 
161 	imsg_init(&c->iev.ibuf, connfd);
162 	c->iev.handler = control_dispatch_imsg;
163 	c->iev.events = EV_READ;
164 	if (ev_add(connfd, c->iev.events, c->iev.handler, &c->iev) == -1) {
165 		message("%s: ev_add: %s", __func__, strerror(errno));
166 		close(connfd);
167 		free(c);
168 		return;
169 	}
170 
171 	TAILQ_INSERT_TAIL(&ctl_conns, c, entry);
172 }
173 
174 struct ctl_conn *
175 control_connbyfd(int fd)
176 {
177 	struct ctl_conn	*c;
178 
179 	TAILQ_FOREACH(c, &ctl_conns, entry) {
180 		if (c->iev.ibuf.fd == fd)
181 			break;
182 	}
183 
184 	return (c);
185 }
186 
187 struct ctl_conn *
188 control_connbypid(pid_t pid)
189 {
190 	struct ctl_conn	*c;
191 
192 	TAILQ_FOREACH(c, &ctl_conns, entry) {
193 		if (c->iev.ibuf.pid == pid)
194 			break;
195 	}
196 
197 	return (c);
198 }
199 
200 void
201 control_close(int fd)
202 {
203 	struct ctl_conn	*c;
204 
205 	if ((c = control_connbyfd(fd)) == NULL) {
206 		message("%s: fd %d: not found", __func__, fd);
207 		return;
208 	}
209 
210 	msgbuf_clear(&c->iev.ibuf.w);
211 	TAILQ_REMOVE(&ctl_conns, c, entry);
212 
213 	ev_del(c->iev.ibuf.fd);
214 	close(c->iev.ibuf.fd);
215 
216 	/* Some file descriptors are available again. */
217 	if (ev_timer_pending(control_state.timeout)) {
218 		ev_timer_cancel(control_state.timeout);
219 		control_state.timeout = 0;
220 		ev_add(control_state.fd, EV_READ, control_accept, NULL);
221 	}
222 
223 	free(c);
224 }
225 
226 void
227 control_dispatch_imsg(int fd, int event, void *bula)
228 {
229 	struct ctl_conn	*c;
230 	struct imsg	 imsg;
231 	ssize_t		 n;
232 
233 	if ((c = control_connbyfd(fd)) == NULL) {
234 		message("%s: fd %d: not found", __func__, fd);
235 		return;
236 	}
237 
238 	if (event & EV_READ) {
239 		if (((n = imsg_read(&c->iev.ibuf)) == -1 && errno != EAGAIN) ||
240 		    n == 0) {
241 			control_close(fd);
242 			return;
243 		}
244 	}
245 	if (event & EV_WRITE) {
246 		if (msgbuf_write(&c->iev.ibuf.w) <= 0 && errno != EAGAIN) {
247 			control_close(fd);
248 			return;
249 		}
250 	}
251 
252 	for (;;) {
253 		if ((n = imsg_get(&c->iev.ibuf, &imsg)) == -1) {
254 			control_close(fd);
255 			return;
256 		}
257 		if (n == 0)
258 			break;
259 
260 		switch (imsg.hdr.type) {
261 		case IMSG_CTL_OPEN_URL: {
262 			static char uri[GEMINI_URL_LEN];
263 
264 			if (IMSG_DATA_SIZE(imsg) >= sizeof(uri))
265 				break;
266 			memset(uri, 0, sizeof(uri));
267 			memcpy(uri, imsg.data, sizeof(uri));
268 			if (uri[IMSG_DATA_SIZE(imsg)-1] != '\0')
269 				break;
270 
271 			ui_remotely_open_link(uri);
272 			break;
273 		}
274 		default:
275 			message("%s: error handling imsg %d", __func__,
276 			    imsg.hdr.type);
277 			break;
278 		}
279 		imsg_free(&imsg);
280 	}
281 
282 	imsg_event_add(&c->iev);
283 }