imsg.c revision 292022 
1/*	$OpenBSD: imsg.c,v 1.12 2015/12/05 13:06:52 claudio 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: head/lib/libopenbsd/imsg.c 292022 2015-12-09 19:21:00Z rodrigc $
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 <errno.h>
27#include <stdlib.h>
28#include <string.h>
29#include <unistd.h>
30
31#include "imsg.h"
32
33int	 imsg_fd_overhead = 0;
34
35int	 imsg_get_fd(struct imsgbuf *);
36
37void
38imsg_init(struct imsgbuf *ibuf, int fd)
39{
40	msgbuf_init(&ibuf->w);
41	memset(&ibuf->r, 0, sizeof(ibuf->r));
42	ibuf->fd = fd;
43	ibuf->w.fd = fd;
44	ibuf->pid = getpid();
45	TAILQ_INIT(&ibuf->fds);
46}
47
48ssize_t
49imsg_read(struct imsgbuf *ibuf)
50{
51	struct msghdr		 msg;
52	struct cmsghdr		*cmsg;
53	union {
54		struct cmsghdr hdr;
55		char	buf[CMSG_SPACE(sizeof(int) * 1)];
56	} cmsgbuf;
57	struct iovec		 iov;
58	ssize_t			 n = -1;
59	int			 fd;
60	struct imsg_fd		*ifd;
61
62	memset(&msg, 0, sizeof(msg));
63	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
64
65	iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
66	iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
67	msg.msg_iov = &iov;
68	msg.msg_iovlen = 1;
69	msg.msg_control = &cmsgbuf.buf;
70	msg.msg_controllen = sizeof(cmsgbuf.buf);
71
72	if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
73		return (-1);
74
75again:
76	if (getdtablecount() + imsg_fd_overhead +
77	    (CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int)
78	    >= getdtablesize()) {
79		errno = EAGAIN;
80		free(ifd);
81		return (-1);
82	}
83
84	if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
85		if (errno == EINTR)
86			goto again;
87		goto fail;
88	}
89
90	ibuf->r.wpos += n;
91
92	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
93	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
94		if (cmsg->cmsg_level == SOL_SOCKET &&
95		    cmsg->cmsg_type == SCM_RIGHTS) {
96			int i;
97			int j;
98
99			/*
100			 * We only accept one file descriptor.  Due to C
101			 * padding rules, our control buffer might contain
102			 * more than one fd, and we must close them.
103			 */
104			j = ((char *)cmsg + cmsg->cmsg_len -
105			    (char *)CMSG_DATA(cmsg)) / sizeof(int);
106			for (i = 0; i < j; i++) {
107				fd = ((int *)CMSG_DATA(cmsg))[i];
108				if (ifd != NULL) {
109					ifd->fd = fd;
110					TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
111					    entry);
112					ifd = NULL;
113				} else
114					close(fd);
115			}
116		}
117		/* we do not handle other ctl data level */
118	}
119
120fail:
121	free(ifd);
122	return (n);
123}
124
125ssize_t
126imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
127{
128	size_t			 av, left, datalen;
129
130	av = ibuf->r.wpos;
131
132	if (IMSG_HEADER_SIZE > av)
133		return (0);
134
135	memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
136	if (imsg->hdr.len < IMSG_HEADER_SIZE ||
137	    imsg->hdr.len > MAX_IMSGSIZE) {
138		errno = ERANGE;
139		return (-1);
140	}
141	if (imsg->hdr.len > av)
142		return (0);
143	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
144	ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
145	if (datalen == 0)
146		imsg->data = NULL;
147	else if ((imsg->data = malloc(datalen)) == NULL)
148		return (-1);
149
150	if (imsg->hdr.flags & IMSGF_HASFD)
151		imsg->fd = imsg_get_fd(ibuf);
152	else
153		imsg->fd = -1;
154
155	memcpy(imsg->data, ibuf->r.rptr, datalen);
156
157	if (imsg->hdr.len < av) {
158		left = av - imsg->hdr.len;
159		memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
160		ibuf->r.wpos = left;
161	} else
162		ibuf->r.wpos = 0;
163
164	return (datalen + IMSG_HEADER_SIZE);
165}
166
167int
168imsg_compose(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
169    pid_t pid, int fd, const void *data, u_int16_t datalen)
170{
171	struct ibuf	*wbuf;
172
173	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
174		return (-1);
175
176	if (imsg_add(wbuf, data, datalen) == -1)
177		return (-1);
178
179	wbuf->fd = fd;
180
181	imsg_close(ibuf, wbuf);
182
183	return (1);
184}
185
186int
187imsg_composev(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
188    pid_t pid, int fd, const struct iovec *iov, int iovcnt)
189{
190	struct ibuf	*wbuf;
191	int		 i, datalen = 0;
192
193	for (i = 0; i < iovcnt; i++)
194		datalen += iov[i].iov_len;
195
196	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
197		return (-1);
198
199	for (i = 0; i < iovcnt; i++)
200		if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
201			return (-1);
202
203	wbuf->fd = fd;
204
205	imsg_close(ibuf, wbuf);
206
207	return (1);
208}
209
210/* ARGSUSED */
211struct ibuf *
212imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
213    pid_t pid, u_int16_t datalen)
214{
215	struct ibuf	*wbuf;
216	struct imsg_hdr	 hdr;
217
218	datalen += IMSG_HEADER_SIZE;
219	if (datalen > MAX_IMSGSIZE) {
220		errno = ERANGE;
221		return (NULL);
222	}
223
224	hdr.type = type;
225	hdr.flags = 0;
226	hdr.peerid = peerid;
227	if ((hdr.pid = pid) == 0)
228		hdr.pid = ibuf->pid;
229	if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
230		return (NULL);
231	}
232	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
233		return (NULL);
234
235	return (wbuf);
236}
237
238int
239imsg_add(struct ibuf *msg, const void *data, u_int16_t datalen)
240{
241	if (datalen)
242		if (ibuf_add(msg, data, datalen) == -1) {
243			ibuf_free(msg);
244			return (-1);
245		}
246	return (datalen);
247}
248
249void
250imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
251{
252	struct imsg_hdr	*hdr;
253
254	hdr = (struct imsg_hdr *)msg->buf;
255
256	hdr->flags &= ~IMSGF_HASFD;
257	if (msg->fd != -1)
258		hdr->flags |= IMSGF_HASFD;
259
260	hdr->len = (u_int16_t)msg->wpos;
261
262	ibuf_close(&ibuf->w, msg);
263}
264
265void
266imsg_free(struct imsg *imsg)
267{
268	free(imsg->data);
269}
270
271int
272imsg_get_fd(struct imsgbuf *ibuf)
273{
274	int		 fd;
275	struct imsg_fd	*ifd;
276
277	if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
278		return (-1);
279
280	fd = ifd->fd;
281	TAILQ_REMOVE(&ibuf->fds, ifd, entry);
282	free(ifd);
283
284	return (fd);
285}
286
287int
288imsg_flush(struct imsgbuf *ibuf)
289{
290	while (ibuf->w.queued)
291		if (msgbuf_write(&ibuf->w) <= 0)
292			return (-1);
293	return (0);
294}
295
296void
297imsg_clear(struct imsgbuf *ibuf)
298{
299	int	fd;
300
301	msgbuf_clear(&ibuf->w);
302	while ((fd = imsg_get_fd(ibuf)) != -1)
303		close(fd);
304}
305