1/*	$OpenBSD: imsg-buffer.c,v 1.7 2015/07/12 18:40:49 nicm 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 * $FreeBSD$
19 */
20
21#include <sys/types.h>
22#include <sys/queue.h>
23#include <sys/socket.h>
24#include <sys/uio.h>
25
26#include <limits.h>
27#include <errno.h>
28#include <stdlib.h>
29#include <string.h>
30#include <unistd.h>
31
32#include "imsg.h"
33
34int	ibuf_realloc(struct ibuf *, size_t);
35void	ibuf_enqueue(struct msgbuf *, struct ibuf *);
36void	ibuf_dequeue(struct msgbuf *, struct ibuf *);
37
38struct ibuf *
39ibuf_open(size_t len)
40{
41	struct ibuf	*buf;
42
43	if ((buf = calloc(1, sizeof(struct ibuf))) == NULL)
44		return (NULL);
45	if ((buf->buf = malloc(len)) == NULL) {
46		free(buf);
47		return (NULL);
48	}
49	buf->size = buf->max = len;
50	buf->fd = -1;
51
52	return (buf);
53}
54
55struct ibuf *
56ibuf_dynamic(size_t len, size_t max)
57{
58	struct ibuf	*buf;
59
60	if (max < len)
61		return (NULL);
62
63	if ((buf = ibuf_open(len)) == NULL)
64		return (NULL);
65
66	if (max > 0)
67		buf->max = max;
68
69	return (buf);
70}
71
72int
73ibuf_realloc(struct ibuf *buf, size_t len)
74{
75	u_char	*b;
76
77	/* on static buffers max is eq size and so the following fails */
78	if (buf->wpos + len > buf->max) {
79		errno = ERANGE;
80		return (-1);
81	}
82
83	b = realloc(buf->buf, buf->wpos + len);
84	if (b == NULL)
85		return (-1);
86	buf->buf = b;
87	buf->size = buf->wpos + len;
88
89	return (0);
90}
91
92int
93ibuf_add(struct ibuf *buf, const void *data, size_t len)
94{
95	if (buf->wpos + len > buf->size)
96		if (ibuf_realloc(buf, len) == -1)
97			return (-1);
98
99	memcpy(buf->buf + buf->wpos, data, len);
100	buf->wpos += len;
101	return (0);
102}
103
104void *
105ibuf_reserve(struct ibuf *buf, size_t len)
106{
107	void	*b;
108
109	if (buf->wpos + len > buf->size)
110		if (ibuf_realloc(buf, len) == -1)
111			return (NULL);
112
113	b = buf->buf + buf->wpos;
114	buf->wpos += len;
115	return (b);
116}
117
118void *
119ibuf_seek(struct ibuf *buf, size_t pos, size_t len)
120{
121	/* only allowed to seek in already written parts */
122	if (pos + len > buf->wpos)
123		return (NULL);
124
125	return (buf->buf + pos);
126}
127
128size_t
129ibuf_size(struct ibuf *buf)
130{
131	return (buf->wpos);
132}
133
134size_t
135ibuf_left(struct ibuf *buf)
136{
137	return (buf->max - buf->wpos);
138}
139
140void
141ibuf_close(struct msgbuf *msgbuf, struct ibuf *buf)
142{
143	ibuf_enqueue(msgbuf, buf);
144}
145
146int
147ibuf_write(struct msgbuf *msgbuf)
148{
149	struct iovec	 iov[IOV_MAX];
150	struct ibuf	*buf;
151	unsigned int	 i = 0;
152	ssize_t	n;
153
154	memset(&iov, 0, sizeof(iov));
155	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
156		if (i >= IOV_MAX)
157			break;
158		iov[i].iov_base = buf->buf + buf->rpos;
159		iov[i].iov_len = buf->wpos - buf->rpos;
160		i++;
161	}
162
163again:
164	if ((n = writev(msgbuf->fd, iov, i)) == -1) {
165		if (errno == EINTR)
166			goto again;
167		if (errno == ENOBUFS)
168			errno = EAGAIN;
169		return (-1);
170	}
171
172	if (n == 0) {			/* connection closed */
173		errno = 0;
174		return (0);
175	}
176
177	msgbuf_drain(msgbuf, n);
178
179	return (1);
180}
181
182void
183ibuf_free(struct ibuf *buf)
184{
185	free(buf->buf);
186	free(buf);
187}
188
189void
190msgbuf_init(struct msgbuf *msgbuf)
191{
192	msgbuf->queued = 0;
193	msgbuf->fd = -1;
194	TAILQ_INIT(&msgbuf->bufs);
195}
196
197void
198msgbuf_drain(struct msgbuf *msgbuf, size_t n)
199{
200	struct ibuf	*buf, *next;
201
202	for (buf = TAILQ_FIRST(&msgbuf->bufs); buf != NULL && n > 0;
203	    buf = next) {
204		next = TAILQ_NEXT(buf, entry);
205		if (buf->rpos + n >= buf->wpos) {
206			n -= buf->wpos - buf->rpos;
207			ibuf_dequeue(msgbuf, buf);
208		} else {
209			buf->rpos += n;
210			n = 0;
211		}
212	}
213}
214
215void
216msgbuf_clear(struct msgbuf *msgbuf)
217{
218	struct ibuf	*buf;
219
220	while ((buf = TAILQ_FIRST(&msgbuf->bufs)) != NULL)
221		ibuf_dequeue(msgbuf, buf);
222}
223
224int
225msgbuf_write(struct msgbuf *msgbuf)
226{
227	struct iovec	 iov[IOV_MAX];
228	struct ibuf	*buf;
229	unsigned int	 i = 0;
230	ssize_t		 n;
231	struct msghdr	 msg;
232	struct cmsghdr	*cmsg;
233	union {
234		struct cmsghdr	hdr;
235		char		buf[CMSG_SPACE(sizeof(int))];
236	} cmsgbuf;
237
238	memset(&iov, 0, sizeof(iov));
239	memset(&msg, 0, sizeof(msg));
240	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
241	TAILQ_FOREACH(buf, &msgbuf->bufs, entry) {
242		if (i >= IOV_MAX)
243			break;
244		iov[i].iov_base = buf->buf + buf->rpos;
245		iov[i].iov_len = buf->wpos - buf->rpos;
246		i++;
247		if (buf->fd != -1)
248			break;
249	}
250
251	msg.msg_iov = iov;
252	msg.msg_iovlen = i;
253
254	if (buf != NULL && buf->fd != -1) {
255		msg.msg_control = (caddr_t)&cmsgbuf.buf;
256		msg.msg_controllen = sizeof(cmsgbuf.buf);
257		cmsg = CMSG_FIRSTHDR(&msg);
258		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
259		cmsg->cmsg_level = SOL_SOCKET;
260		cmsg->cmsg_type = SCM_RIGHTS;
261		*(int *)CMSG_DATA(cmsg) = buf->fd;
262	}
263
264again:
265	if ((n = sendmsg(msgbuf->fd, &msg, 0)) == -1) {
266		if (errno == EINTR)
267			goto again;
268		if (errno == ENOBUFS)
269			errno = EAGAIN;
270		return (-1);
271	}
272
273	if (n == 0) {			/* connection closed */
274		errno = 0;
275		return (0);
276	}
277
278	/*
279	 * assumption: fd got sent if sendmsg sent anything
280	 * this works because fds are passed one at a time
281	 */
282	if (buf != NULL && buf->fd != -1) {
283		close(buf->fd);
284		buf->fd = -1;
285	}
286
287	msgbuf_drain(msgbuf, n);
288
289	return (1);
290}
291
292void
293ibuf_enqueue(struct msgbuf *msgbuf, struct ibuf *buf)
294{
295	TAILQ_INSERT_TAIL(&msgbuf->bufs, buf, entry);
296	msgbuf->queued++;
297}
298
299void
300ibuf_dequeue(struct msgbuf *msgbuf, struct ibuf *buf)
301{
302	TAILQ_REMOVE(&msgbuf->bufs, buf, entry);
303
304	if (buf->fd != -1)
305		close(buf->fd);
306
307	msgbuf->queued--;
308	ibuf_free(buf);
309}
310