1/*	$OpenBSD: imsg.c,v 1.13 2015/12/09 11:54:12 tb 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/queue.h>
21#include <sys/socket.h>
22#include <sys/uio.h>
23
24#include <errno.h>
25#include <stdlib.h>
26#include <string.h>
27#include <unistd.h>
28
29#include "imsg.h"
30
31int	 imsg_fd_overhead = 0;
32
33int	 imsg_get_fd(struct imsgbuf *);
34
35void
36imsg_init(struct imsgbuf *ibuf, int fd)
37{
38	msgbuf_init(&ibuf->w);
39	memset(&ibuf->r, 0, sizeof(ibuf->r));
40	ibuf->fd = fd;
41	ibuf->w.fd = fd;
42	ibuf->pid = getpid();
43	TAILQ_INIT(&ibuf->fds);
44}
45
46ssize_t
47imsg_read(struct imsgbuf *ibuf)
48{
49	struct msghdr		 msg;
50	struct cmsghdr		*cmsg;
51	union {
52		struct cmsghdr hdr;
53		char	buf[CMSG_SPACE(sizeof(int) * 1)];
54	} cmsgbuf;
55	struct iovec		 iov;
56	ssize_t			 n = -1;
57	int			 fd;
58	struct imsg_fd		*ifd;
59
60	memset(&msg, 0, sizeof(msg));
61	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
62
63	iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
64	iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
65	msg.msg_iov = &iov;
66	msg.msg_iovlen = 1;
67	msg.msg_control = &cmsgbuf.buf;
68	msg.msg_controllen = sizeof(cmsgbuf.buf);
69
70	if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
71		return (-1);
72
73again:
74	if (getdtablecount() + imsg_fd_overhead +
75	    (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
76	    >= getdtablesize()) {
77		errno = EAGAIN;
78		free(ifd);
79		return (-1);
80	}
81
82	if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
83		if (errno == EINTR)
84			goto again;
85		goto fail;
86	}
87
88	ibuf->r.wpos += n;
89
90	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
91	    cmsg = CMSG_NXTHDR(&msg, cmsg)) {
92		if (cmsg->cmsg_level == SOL_SOCKET &&
93		    cmsg->cmsg_type == SCM_RIGHTS) {
94			int i;
95			int j;
96
97			/*
98			 * We only accept one file descriptor.  Due to C
99			 * padding rules, our control buffer might contain
100			 * more than one fd, and we must close them.
101			 */
102			j = ((char *)cmsg + cmsg->cmsg_len -
103			    (char *)CMSG_DATA(cmsg)) / sizeof(int);
104			for (i = 0; i < j; i++) {
105				fd = ((int *)CMSG_DATA(cmsg))[i];
106				if (ifd != NULL) {
107					ifd->fd = fd;
108					TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
109					    entry);
110					ifd = NULL;
111				} else
112					close(fd);
113			}
114		}
115		/* we do not handle other ctl data level */
116	}
117
118fail:
119	free(ifd);
120	return (n);
121}
122
123ssize_t
124imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
125{
126	size_t			 av, left, datalen;
127
128	av = ibuf->r.wpos;
129
130	if (IMSG_HEADER_SIZE > av)
131		return (0);
132
133	memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
134	if (imsg->hdr.len < IMSG_HEADER_SIZE ||
135	    imsg->hdr.len > MAX_IMSGSIZE) {
136		errno = ERANGE;
137		return (-1);
138	}
139	if (imsg->hdr.len > av)
140		return (0);
141	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
142	ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
143	if (datalen == 0)
144		imsg->data = NULL;
145	else if ((imsg->data = malloc(datalen)) == NULL)
146		return (-1);
147
148	if (imsg->hdr.flags & IMSGF_HASFD)
149		imsg->fd = imsg_get_fd(ibuf);
150	else
151		imsg->fd = -1;
152
153	memcpy(imsg->data, ibuf->r.rptr, datalen);
154
155	if (imsg->hdr.len < av) {
156		left = av - imsg->hdr.len;
157		memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
158		ibuf->r.wpos = left;
159	} else
160		ibuf->r.wpos = 0;
161
162	return (datalen + IMSG_HEADER_SIZE);
163}
164
165int
166imsg_compose(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
167    pid_t pid, int fd, const void *data, u_int16_t datalen)
168{
169	struct ibuf	*wbuf;
170
171	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
172		return (-1);
173
174	if (imsg_add(wbuf, data, datalen) == -1)
175		return (-1);
176
177	wbuf->fd = fd;
178
179	imsg_close(ibuf, wbuf);
180
181	return (1);
182}
183
184int
185imsg_composev(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
186    pid_t pid, int fd, const struct iovec *iov, int iovcnt)
187{
188	struct ibuf	*wbuf;
189	int		 i, datalen = 0;
190
191	for (i = 0; i < iovcnt; i++)
192		datalen += iov[i].iov_len;
193
194	if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
195		return (-1);
196
197	for (i = 0; i < iovcnt; i++)
198		if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
199			return (-1);
200
201	wbuf->fd = fd;
202
203	imsg_close(ibuf, wbuf);
204
205	return (1);
206}
207
208/* ARGSUSED */
209struct ibuf *
210imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
211    pid_t pid, u_int16_t datalen)
212{
213	struct ibuf	*wbuf;
214	struct imsg_hdr	 hdr;
215
216	datalen += IMSG_HEADER_SIZE;
217	if (datalen > MAX_IMSGSIZE) {
218		errno = ERANGE;
219		return (NULL);
220	}
221
222	hdr.type = type;
223	hdr.flags = 0;
224	hdr.peerid = peerid;
225	if ((hdr.pid = pid) == 0)
226		hdr.pid = ibuf->pid;
227	if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
228		return (NULL);
229	}
230	if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
231		return (NULL);
232
233	return (wbuf);
234}
235
236int
237imsg_add(struct ibuf *msg, const void *data, u_int16_t datalen)
238{
239	if (datalen)
240		if (ibuf_add(msg, data, datalen) == -1) {
241			ibuf_free(msg);
242			return (-1);
243		}
244	return (datalen);
245}
246
247void
248imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
249{
250	struct imsg_hdr	*hdr;
251
252	hdr = (struct imsg_hdr *)msg->buf;
253
254	hdr->flags &= ~IMSGF_HASFD;
255	if (msg->fd != -1)
256		hdr->flags |= IMSGF_HASFD;
257
258	hdr->len = (u_int16_t)msg->wpos;
259
260	ibuf_close(&ibuf->w, msg);
261}
262
263void
264imsg_free(struct imsg *imsg)
265{
266	free(imsg->data);
267}
268
269int
270imsg_get_fd(struct imsgbuf *ibuf)
271{
272	int		 fd;
273	struct imsg_fd	*ifd;
274
275	if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
276		return (-1);
277
278	fd = ifd->fd;
279	TAILQ_REMOVE(&ibuf->fds, ifd, entry);
280	free(ifd);
281
282	return (fd);
283}
284
285int
286imsg_flush(struct imsgbuf *ibuf)
287{
288	while (ibuf->w.queued)
289		if (msgbuf_write(&ibuf->w) <= 0)
290			return (-1);
291	return (0);
292}
293
294void
295imsg_clear(struct imsgbuf *ibuf)
296{
297	int	fd;
298
299	msgbuf_clear(&ibuf->w);
300	while ((fd = imsg_get_fd(ibuf)) != -1)
301		close(fd);
302}
303