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1 /* $OpenBSD: imsg.c,v 1.17 2022/01/28 10:41:44 claudio Exp $ */
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 */
19 #include "../config.h"
21 #include <sys/types.h>
22 #include <sys/socket.h>
23 #include <sys/uio.h>
25 #include <errno.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <unistd.h>
30 #include "imsg.h"
32 int imsg_fd_overhead = 0;
34 static int imsg_get_fd(struct imsgbuf *);
36 void
37 imsg_init(struct imsgbuf *ibuf, int fd)
38 {
39 msgbuf_init(&ibuf->w);
40 memset(&ibuf->r, 0, sizeof(ibuf->r));
41 ibuf->fd = fd;
42 ibuf->w.fd = fd;
43 ibuf->pid = getpid();
44 TAILQ_INIT(&ibuf->fds);
45 }
47 ssize_t
48 imsg_read(struct imsgbuf *ibuf)
49 {
50 struct msghdr msg;
51 struct cmsghdr *cmsg;
52 union {
53 struct cmsghdr hdr;
54 char buf[CMSG_SPACE(sizeof(int) * 1)];
55 } cmsgbuf;
56 struct iovec iov;
57 ssize_t n = -1;
58 int fd;
59 struct imsg_fd *ifd;
61 memset(&msg, 0, sizeof(msg));
62 memset(&cmsgbuf, 0, sizeof(cmsgbuf));
64 iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
65 iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
66 msg.msg_iov = &iov;
67 msg.msg_iovlen = 1;
68 msg.msg_control = &cmsgbuf.buf;
69 msg.msg_controllen = sizeof(cmsgbuf.buf);
71 if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
72 return (-1);
74 again:
75 if (getdtablecount() + imsg_fd_overhead +
76 (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
77 >= getdtablesize()) {
78 errno = EAGAIN;
79 free(ifd);
80 return (-1);
81 }
83 if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
84 if (errno == EINTR)
85 goto again;
86 goto fail;
87 }
89 ibuf->r.wpos += n;
91 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
92 cmsg = CMSG_NXTHDR(&msg, cmsg)) {
93 if (cmsg->cmsg_level == SOL_SOCKET &&
94 cmsg->cmsg_type == SCM_RIGHTS) {
95 int i;
96 int j;
98 /*
99 * We only accept one file descriptor. Due to C
100 * padding rules, our control buffer might contain
101 * more than one fd, and we must close them.
102 */
103 j = ((char *)cmsg + cmsg->cmsg_len -
104 (char *)CMSG_DATA(cmsg)) / sizeof(int);
105 for (i = 0; i < j; i++) {
106 fd = ((int *)CMSG_DATA(cmsg))[i];
107 if (ifd != NULL) {
108 ifd->fd = fd;
109 TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
110 entry);
111 ifd = NULL;
112 } else
113 close(fd);
116 /* we do not handle other ctl data level */
119 fail:
120 free(ifd);
121 return (n);
124 ssize_t
125 imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
127 size_t av, left, datalen;
129 av = ibuf->r.wpos;
131 if (IMSG_HEADER_SIZE > av)
132 return (0);
134 memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
135 if (imsg->hdr.len < IMSG_HEADER_SIZE ||
136 imsg->hdr.len > MAX_IMSGSIZE) {
137 errno = ERANGE;
138 return (-1);
140 if (imsg->hdr.len > av)
141 return (0);
142 datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
143 ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
144 if (datalen == 0)
145 imsg->data = NULL;
146 else if ((imsg->data = malloc(datalen)) == NULL)
147 return (-1);
149 if (imsg->hdr.flags & IMSGF_HASFD)
150 imsg->fd = imsg_get_fd(ibuf);
151 else
152 imsg->fd = -1;
154 if (datalen != 0)
155 memcpy(imsg->data, ibuf->r.rptr, datalen);
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;
164 return (datalen + IMSG_HEADER_SIZE);
167 int
168 imsg_compose(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
169 int fd, const void *data, uint16_t datalen)
171 struct ibuf *wbuf;
173 if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
174 return (-1);
176 if (imsg_add(wbuf, data, datalen) == -1)
177 return (-1);
179 wbuf->fd = fd;
181 imsg_close(ibuf, wbuf);
183 return (1);
186 int
187 imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
188 int fd, const struct iovec *iov, int iovcnt)
190 struct ibuf *wbuf;
191 int i, datalen = 0;
193 for (i = 0; i < iovcnt; i++)
194 datalen += iov[i].iov_len;
196 if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
197 return (-1);
199 for (i = 0; i < iovcnt; i++)
200 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
201 return (-1);
203 wbuf->fd = fd;
205 imsg_close(ibuf, wbuf);
207 return (1);
210 /* ARGSUSED */
211 struct ibuf *
212 imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid, pid_t pid,
213 uint16_t datalen)
215 struct ibuf *wbuf;
216 struct imsg_hdr hdr;
218 datalen += IMSG_HEADER_SIZE;
219 if (datalen > MAX_IMSGSIZE) {
220 errno = ERANGE;
221 return (NULL);
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);
232 if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
233 return (NULL);
235 return (wbuf);
238 int
239 imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
241 if (datalen)
242 if (ibuf_add(msg, data, datalen) == -1) {
243 ibuf_free(msg);
244 return (-1);
246 return (datalen);
249 void
250 imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
252 struct imsg_hdr *hdr;
254 hdr = (struct imsg_hdr *)msg->buf;
256 hdr->flags &= ~IMSGF_HASFD;
257 if (msg->fd != -1)
258 hdr->flags |= IMSGF_HASFD;
260 hdr->len = (uint16_t)msg->wpos;
262 ibuf_close(&ibuf->w, msg);
265 void
266 imsg_free(struct imsg *imsg)
268 freezero(imsg->data, imsg->hdr.len - IMSG_HEADER_SIZE);
271 static int
272 imsg_get_fd(struct imsgbuf *ibuf)
274 int fd;
275 struct imsg_fd *ifd;
277 if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
278 return (-1);
280 fd = ifd->fd;
281 TAILQ_REMOVE(&ibuf->fds, ifd, entry);
282 free(ifd);
284 return (fd);
287 int
288 imsg_flush(struct imsgbuf *ibuf)
290 while (ibuf->w.queued)
291 if (msgbuf_write(&ibuf->w) <= 0)
292 return (-1);
293 return (0);
296 void
297 imsg_clear(struct imsgbuf *ibuf)
299 int fd;
301 msgbuf_clear(&ibuf->w);
302 while ((fd = imsg_get_fd(ibuf)) != -1)
303 close(fd);