1 /*	$OpenBSD: imsg-buffer.c,v 1.12 2019/01/20 02:50:03 bcook 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 <sys/types.h>
20 #include <sys/socket.h>
21 #include <sys/uio.h>
22 
23 #include <limits.h>
24 #include <errno.h>
25 #include <stdlib.h>
26 #include <string.h>
27 #include <unistd.h>
28 
29 #include "imsg.h"
30 
31 static int	ibuf_realloc(struct ibuf *, size_t);
32 static void	ibuf_enqueue(struct msgbuf *, struct ibuf *);
33 static void	ibuf_dequeue(struct msgbuf *, struct ibuf *);
34 
35 struct ibuf *
36 ibuf_open(size_t len)
37 {
38 	struct ibuf	*buf;
39 
40 	if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
41 		return (NULL);
42 	if ((buf->buf = malloc(len)) == NULL) {
43 		free(buf);
44 		return (NULL);
45 	}
46 	buf->size = buf->max = len;
47 	buf->fd = -1;
48 
49 	return (buf);
50 }
51 
52 struct ibuf *
53 ibuf_dynamic(size_t len, size_t max)
54 {
55 	struct ibuf	*buf;
56 
57 	if (max < len)
58 		return (NULL);
59 
60 	if ((buf = ibuf_open(len)) == NULL)
61 		return (NULL);
62 
63 	if (max > 0)
64 		buf->max = max;
65 
66 	return (buf);
67 }
68 
69 static int
70 ibuf_realloc(struct ibuf *buf, size_t len)
71 {
72 	unsigned char	*b;
73 
74 	/* on static buffers max is eq size and so the following fails */
75 	if (buf->wpos + len > buf->max) {
76 		errno = ERANGE;
77 		return (-1);
78 	}
79 
80 	b = recallocarray(buf->buf, buf->size, buf->wpos + len, 1);
81 	if (b == NULL)
82 		return (-1);
83 	buf->buf = b;
84 	buf->size = buf->wpos + len;
85 
86 	return (0);
87 }
88 
89 int
90 ibuf_add(struct ibuf *buf, const void *data, size_t len)
91 {
92 	if (buf->wpos + len > buf->size)
93 		if (ibuf_realloc(buf, len) == -1)
94 			return (-1);
95 
96 	memcpy(buf->buf + buf->wpos, data, len);
97 	buf->wpos += len;
98 	return (0);
99 }
100 
101 void *
102 ibuf_reserve(struct ibuf *buf, size_t len)
103 {
104 	void	*b;
105 
106 	if (buf->wpos + len > buf->size)
107 		if (ibuf_realloc(buf, len) == -1)
108 			return (NULL);
109 
110 	b = buf->buf + buf->wpos;
111 	buf->wpos += len;
112 	return (b);
113 }
114 
115 void *
116 ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
117 {
118 	/* only allowed to seek in already written parts */
119 	if (pos + len > buf->wpos)
120 		return (NULL);
121 
122 	return (buf->buf + pos);
123 }
124 
125 size_t
126 ibuf_size(struct ibuf *buf)
127 {
128 	return (buf->wpos);
129 }
130 
131 size_t
132 ibuf_left(struct ibuf *buf)
133 {
134 	return (buf->max - buf->wpos);
135 }
136 
137 void
138 ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
139 {
140 	ibuf_enqueue(msgbuf, buf);
141 }
142 
143 int
144 ibuf_write(struct msgbuf *msgbuf)
145 {
146 	struct iovec	 iov[IOV_MAX];
147 	struct ibuf	*buf;
148 	unsigned int	 i = 0;
149 	ssize_t	n;
150 
151 	memset(&iov, 0, sizeof(iov));
152 	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
153 		if (i >= IOV_MAX)
154 			break;
155 		iov[i].iov_base = buf->buf + buf->rpos;
156 		iov[i].iov_len = buf->wpos - buf->rpos;
157 		i++;
158 	}
159 
160 again:
161 	if ((n = writev(msgbuf->fd, iov, i)) == -1) {
162 		if (errno == EINTR)
163 			goto again;
164 		if (errno == ENOBUFS)
165 			errno = EAGAIN;
166 		return (-1);
167 	}
168 
169 	if (n == 0) {			/* connection closed */
170 		errno = 0;
171 		return (0);
172 	}
173 
174 	msgbuf_drain(msgbuf, n);
175 
176 	return (1);
177 }
178 
179 void
180 ibuf_free(struct ibuf *buf)
181 {
182 	if (buf == NULL)
183 		return;
184 	freezero(buf->buf, buf->size);
185 	free(buf);
186 }
187 
188 void
189 msgbuf_init(struct msgbuf *msgbuf)
190 {
191 	msgbuf->queued = 0;
192 	msgbuf->fd = -1;
193 	TAILQ_INIT(&msgbuf->bufs);
194 }
195 
196 void
197 msgbuf_drain(struct msgbuf *msgbuf, size_t n)
198 {
199 	struct ibuf	*buf, *next;
200 
201 	for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
202 	    buf = next) {
203 		next = TAILQ_NEXT(buf, entry);
204 		if (buf->rpos + n >= buf->wpos) {
205 			n -= buf->wpos - buf->rpos;
206 			ibuf_dequeue(msgbuf, buf);
207 		} else {
208 			buf->rpos += n;
209 			n = 0;
210 		}
211 	}
212 }
213 
214 void
215 msgbuf_clear(struct msgbuf *msgbuf)
216 {
217 	struct ibuf	*buf;
218 
219 	while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
220 		ibuf_dequeue(msgbuf, buf);
221 }
222 
223 int
224 msgbuf_write(struct msgbuf *msgbuf)
225 {
226 	struct iovec	 iov[IOV_MAX];
227 	struct ibuf	*buf;
228 	unsigned int	 i = 0;
229 	ssize_t		 n;
230 	struct msghdr	 msg;
231 	struct cmsghdr	*cmsg;
232 	union {
233 		struct cmsghdr	hdr;
234 		char		buf[CMSG_SPACE(sizeof(int))];
235 	} cmsgbuf;
236 
237 	memset(&iov, 0, sizeof(iov));
238 	memset(&msg, 0, sizeof(msg));
239 	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
240 	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
241 		if (i >= IOV_MAX)
242 			break;
243 		iov[i].iov_base = buf->buf + buf->rpos;
244 		iov[i].iov_len = buf->wpos - buf->rpos;
245 		i++;
246 		if (buf->fd != -1)
247 			break;
248 	}
249 
250 	msg.msg_iov = iov;
251 	msg.msg_iovlen = i;
252 
253 	if (buf != NULL && buf->fd != -1) {
254 		msg.msg_control = (caddr_t)&cmsgbuf.buf;
255 		msg.msg_controllen = sizeof(cmsgbuf.buf);
256 		cmsg = CMSG_FIRSTHDR(&msg);
257 		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
258 		cmsg->cmsg_level = SOL_SOCKET;
259 		cmsg->cmsg_type = SCM_RIGHTS;
260 		*(int *)CMSG_DATA(cmsg) = buf->fd;
261 	}
262 
263 again:
264 	if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
265 		if (errno == EINTR)
266 			goto again;
267 		if (errno == ENOBUFS)
268 			errno = EAGAIN;
269 		return (-1);
270 	}
271 
272 	if (n == 0) {			/* connection closed */
273 		errno = 0;
274 		return (0);
275 	}
276 
277 	/*
278 	 * assumption: fd got sent if sendmsg sent anything
279 	 * this works because fds are passed one at a time
280 	 */
281 	if (buf != NULL && buf->fd != -1) {
282 		close(buf->fd);
283 		buf->fd = -1;
284 	}
285 
286 	msgbuf_drain(msgbuf, n);
287 
288 	return (1);
289 }
290 
291 static void
292 ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
293 {
294 	TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
295 	msgbuf->queued++;
296 }
297 
298 static void
299 ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
300 {
301 	TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
302 
303 	if (buf->fd != -1)
304 		close(buf->fd);
305 
306 	msgbuf->queued--;
307 	ibuf_free(buf);
308 }