lib/imsg.c

   1 /*      $OpenBSD$       */
   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 <zebra.h>
  20
  21 #include "openbsd-queue.h"
  22 #include "imsg.h"
  23
  24 int      imsg_fd_overhead = 0;
  25
  26 int      imsg_get_fd(struct imsgbuf *);
  27
  28 #ifndef __OpenBSD__
  29 /*
  30  * The original code calls getdtablecount() which is OpenBSD specific. Use
  31  * available_fds() from OpenSMTPD instead.
  32  */
  33 static int
  34 available_fds(unsigned int n)
  35 {
  36         unsigned int    i;
  37         int             ret, fds[256];
  38
  39         if (n > (sizeof(fds)/sizeof(fds[0])))
  40                 return (1);
  41
  42         ret = 0;
  43         for (i = 0; i < n; i++) {
  44                 fds[i] = -1;
  45                 if ((fds[i] = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
  46                         if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
  47                                 fds[i] = socket(AF_INET6, SOCK_DGRAM, 0);
  48                         if (fds[i] < 0) {
  49                                 ret = 1;
  50                                 break;
  51                         }
  52                 }
  53         }
  54
  55         for (i = 0; i < n && fds[i] >= 0; i++)
  56                 close(fds[i]);
  57
  58         return (ret);
  59 }
  60 #endif
  61
  62 void
  63 imsg_init(struct imsgbuf *ibuf, int fd)
  64 {
  65         msgbuf_init(&ibuf->w);
  66         memset(&ibuf->r, 0, sizeof(ibuf->r));
  67         ibuf->fd = fd;
  68         ibuf->w.fd = fd;
  69         ibuf->pid = getpid();
  70         TAILQ_INIT(&ibuf->fds);
  71 }
  72
  73 ssize_t
  74 imsg_read(struct imsgbuf *ibuf)
  75 {
  76         struct msghdr            msg;
  77         struct cmsghdr          *cmsg;
  78         union {
  79                 struct cmsghdr hdr;
  80                 char    buf[CMSG_SPACE(sizeof(int) * 1)];
  81         } cmsgbuf;
  82         struct iovec             iov;
  83         ssize_t                  n = -1;
  84         int                      fd;
  85         struct imsg_fd          *ifd;
  86
  87         memset(&msg, 0, sizeof(msg));
  88         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
  89
  90         iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
  91         iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
  92         msg.msg_iov = &iov;
  93         msg.msg_iovlen = 1;
  94         msg.msg_control = &cmsgbuf.buf;
  95         msg.msg_controllen = sizeof(cmsgbuf.buf);
  96
  97         if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
  98                 return (-1);
  99
 100 again:
 101 #ifdef __OpenBSD__
 102         if (getdtablecount() + imsg_fd_overhead +
 103             (int)((CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))
 104             >= getdtablesize()) {
 105 #else
 106         if (available_fds(imsg_fd_overhead +
 107             (CMSG_SPACE(sizeof(int))-CMSG_SPACE(0))/sizeof(int))) {
 108 #endif
 109                 errno = EAGAIN;
 110                 free(ifd);
 111                 return (-1);
 112         }
 113
 114         if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
 115                 if (errno == EINTR)
 116                         goto again;
 117                 goto fail;
 118         }
 119
 120         ibuf->r.wpos += n;
 121
 122         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
 123             cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 124                 if (cmsg->cmsg_level == SOL_SOCKET &&
 125                     cmsg->cmsg_type == SCM_RIGHTS) {
 126                         int i;
 127                         int j;
 128
 129                         /*
 130                          * We only accept one file descriptor.  Due to C
 131                          * padding rules, our control buffer might contain
 132                          * more than one fd, and we must close them.
 133                          */
 134                         j = ((char *)cmsg + cmsg->cmsg_len -
 135                             (char *)CMSG_DATA(cmsg)) / sizeof(int);
 136                         for (i = 0; i < j; i++) {
 137                                 fd = ((int *)CMSG_DATA(cmsg))[i];
 138                                 if (ifd != NULL) {
 139                                         ifd->fd = fd;
 140                                         TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
 141                                             entry);
 142                                         ifd = NULL;
 143                                 } else
 144                                         close(fd);
 145                         }
 146                 }
 147                 /* we do not handle other ctl data level */
 148         }
 149
 150 fail:
 151         free(ifd);
 152         return (n);
 153 }
 154
 155 ssize_t
 156 imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 157 {
 158         size_t                   av, left, datalen;
 159
 160         av = ibuf->r.wpos;
 161
 162         if (IMSG_HEADER_SIZE > av)
 163                 return (0);
 164
 165         memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
 166         if (imsg->hdr.len < IMSG_HEADER_SIZE ||
 167             imsg->hdr.len > MAX_IMSGSIZE) {
 168                 errno = ERANGE;
 169                 return (-1);
 170         }
 171         if (imsg->hdr.len > av)
 172                 return (0);
 173         datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
 174         ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
 175         if (datalen == 0)
 176                 imsg->data = NULL;
 177         else if ((imsg->data = malloc(datalen)) == NULL)
 178                 return (-1);
 179
 180         if (imsg->hdr.flags & IMSGF_HASFD)
 181                 imsg->fd = imsg_get_fd(ibuf);
 182         else
 183                 imsg->fd = -1;
 184
 185         memcpy(imsg->data, ibuf->r.rptr, datalen);
 186
 187         if (imsg->hdr.len < av) {
 188                 left = av - imsg->hdr.len;
 189                 memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
 190                 ibuf->r.wpos = left;
 191         } else
 192                 ibuf->r.wpos = 0;
 193
 194         return (datalen + IMSG_HEADER_SIZE);
 195 }
 196
 197 int
 198 imsg_compose(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
 199     pid_t pid, int fd, const void *data, u_int16_t datalen)
 200 {
 201         struct ibuf     *wbuf;
 202
 203         if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
 204                 return (-1);
 205
 206         if (imsg_add(wbuf, data, datalen) == -1)
 207                 return (-1);
 208
 209         wbuf->fd = fd;
 210
 211         imsg_close(ibuf, wbuf);
 212
 213         return (1);
 214 }
 215
 216 int
 217 imsg_composev(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
 218     pid_t pid, int fd, const struct iovec *iov, int iovcnt)
 219 {
 220         struct ibuf     *wbuf;
 221         int              i, datalen = 0;
 222
 223         for (i = 0; i < iovcnt; i++)
 224                 datalen += iov[i].iov_len;
 225
 226         if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
 227                 return (-1);
 228
 229         for (i = 0; i < iovcnt; i++)
 230                 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
 231                         return (-1);
 232
 233         wbuf->fd = fd;
 234
 235         imsg_close(ibuf, wbuf);
 236
 237         return (1);
 238 }
 239
 240 /* ARGSUSED */
 241 struct ibuf *
 242 imsg_create(struct imsgbuf *ibuf, u_int32_t type, u_int32_t peerid,
 243     pid_t pid, u_int16_t datalen)
 244 {
 245         struct ibuf     *wbuf;
 246         struct imsg_hdr  hdr;
 247
 248         datalen += IMSG_HEADER_SIZE;
 249         if (datalen > MAX_IMSGSIZE) {
 250                 errno = ERANGE;
 251                 return (NULL);
 252         }
 253
 254         hdr.type = type;
 255         hdr.flags = 0;
 256         hdr.peerid = peerid;
 257         if ((hdr.pid = pid) == 0)
 258                 hdr.pid = ibuf->pid;
 259         if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
 260                 return (NULL);
 261         }
 262         if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
 263                 return (NULL);
 264
 265         return (wbuf);
 266 }
 267
 268 int
 269 imsg_add(struct ibuf *msg, const void *data, u_int16_t datalen)
 270 {
 271         if (datalen)
 272                 if (ibuf_add(msg, data, datalen) == -1) {
 273                         ibuf_free(msg);
 274                         return (-1);
 275                 }
 276         return (datalen);
 277 }
 278
 279 void
 280 imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
 281 {
 282         struct imsg_hdr *hdr;
 283
 284         hdr = (struct imsg_hdr *)msg->buf;
 285
 286         hdr->flags &= ~IMSGF_HASFD;
 287         if (msg->fd != -1)
 288                 hdr->flags |= IMSGF_HASFD;
 289
 290         hdr->len = (u_int16_t)msg->wpos;
 291
 292         ibuf_close(&ibuf->w, msg);
 293 }
 294
 295 void
 296 imsg_free(struct imsg *imsg)
 297 {
 298         free(imsg->data);
 299 }
 300
 301 int
 302 imsg_get_fd(struct imsgbuf *ibuf)
 303 {
 304         int              fd;
 305         struct imsg_fd  *ifd;
 306
 307         if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
 308                 return (-1);
 309
 310         fd = ifd->fd;
 311         TAILQ_REMOVE(&ibuf->fds, ifd, entry);
 312         free(ifd);
 313
 314         return (fd);
 315 }
 316
 317 int
 318 imsg_flush(struct imsgbuf *ibuf)
 319 {
 320         while (ibuf->w.queued)
 321                 if (msgbuf_write(&ibuf->w) <= 0)
 322                         return (-1);
 323         return (0);
 324 }
 325
 326 void
 327 imsg_clear(struct imsgbuf *ibuf)
 328 {
 329         int     fd;
 330
 331         msgbuf_clear(&ibuf->w);
 332         while ((fd = imsg_get_fd(ibuf)) != -1)
 333                 close(fd);
 334 }