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 "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 available_fds(unsigned int n)
  34 {
  35         unsigned int i;
  36         int ret, fds[256];
  37
  38         if (n > (sizeof(fds) / sizeof(fds[0])))
  39                 return (1);
  40
  41         ret = 0;
  42         for (i = 0; i < n; i++) {
  43                 fds[i] = -1;
  44                 if ((fds[i] = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
  45                         if (errno == EAFNOSUPPORT || errno == EPROTONOSUPPORT)
  46                                 fds[i] = socket(AF_INET6, SOCK_DGRAM, 0);
  47                         if (fds[i] < 0) {
  48                                 ret = 1;
  49                                 break;
  50                         }
  51                 }
  52         }
  53
  54         for (i = 0; i < n && fds[i] >= 0; i++)
  55                 close(fds[i]);
  56
  57         return (ret);
  58 }
  59 #endif
  60
  61 void imsg_init(struct imsgbuf *ibuf, int fd)
  62 {
  63         msgbuf_init(&ibuf->w);
  64         memset(&ibuf->r, 0, sizeof(ibuf->r));
  65         ibuf->fd = fd;
  66         ibuf->w.fd = fd;
  67         ibuf->pid = getpid();
  68         TAILQ_INIT(&ibuf->fds);
  69 }
  70
  71 ssize_t imsg_read(struct imsgbuf *ibuf)
  72 {
  73         struct msghdr msg;
  74         struct cmsghdr *cmsg;
  75         union {
  76                 struct cmsghdr hdr;
  77                 char buf[CMSG_SPACE(sizeof(int) * 1)];
  78         } cmsgbuf;
  79         struct iovec iov;
  80         ssize_t n = -1;
  81         int fd;
  82         struct imsg_fd *ifd;
  83
  84         memset(&msg, 0, sizeof(msg));
  85         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
  86
  87         iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
  88         iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
  89         msg.msg_iov = &iov;
  90         msg.msg_iovlen = 1;
  91         msg.msg_control = &cmsgbuf.buf;
  92         msg.msg_controllen = sizeof(cmsgbuf.buf);
  93
  94         if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
  95                 return (-1);
  96
  97 again:
  98 #ifdef __OpenBSD__
  99         if (getdtablecount() + imsg_fd_overhead
 100                     + (int)((CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))
 101                             / sizeof(int))
 102             >= getdtablesize()) {
 103 #else
 104         if (available_fds(imsg_fd_overhead
 105                           + (CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))
 106                                     / sizeof(int))) {
 107 #endif
 108                 errno = EAGAIN;
 109                 free(ifd);
 110                 return (-1);
 111         }
 112
 113         if ((n = recvmsg(ibuf->fd, &msg, 0)) == -1) {
 114                 if (errno == EINTR)
 115                         goto again;
 116                 goto fail;
 117         }
 118
 119         ibuf->r.wpos += n;
 120
 121         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
 122              cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 123                 if (cmsg->cmsg_level == SOL_SOCKET
 124                     && cmsg->cmsg_type == SCM_RIGHTS) {
 125                         int i;
 126                         int j;
 127
 128                         /*
 129                          * We only accept one file descriptor.  Due to C
 130                          * padding rules, our control buffer might contain
 131                          * more than one fd, and we must close them.
 132                          */
 133                         j = ((char *)cmsg + cmsg->cmsg_len
 134                              - (char *)CMSG_DATA(cmsg))
 135                             / 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 imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 156 {
 157         size_t av, left, datalen;
 158
 159         av = ibuf->r.wpos;
 160
 161         if (IMSG_HEADER_SIZE > av)
 162                 return (0);
 163
 164         memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
 165         if (imsg->hdr.len < IMSG_HEADER_SIZE || imsg->hdr.len > MAX_IMSGSIZE) {
 166                 errno = ERANGE;
 167                 return (-1);
 168         }
 169         if (imsg->hdr.len > av)
 170                 return (0);
 171         datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
 172         ibuf->r.rptr = ibuf->r.buf + IMSG_HEADER_SIZE;
 173         if (datalen == 0)
 174                 imsg->data = NULL;
 175         else if ((imsg->data = malloc(datalen)) == NULL)
 176                 return (-1);
 177
 178         if (imsg->hdr.flags & IMSGF_HASFD)
 179                 imsg->fd = imsg_get_fd(ibuf);
 180         else
 181                 imsg->fd = -1;
 182
 183         if (imsg->data)
 184                 memcpy(imsg->data, ibuf->r.rptr, datalen);
 185
 186         if (imsg->hdr.len < av) {
 187                 left = av - imsg->hdr.len;
 188                 memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
 189                 ibuf->r.wpos = left;
 190         } else
 191                 ibuf->r.wpos = 0;
 192
 193         return (datalen + IMSG_HEADER_SIZE);
 194 }
 195
 196 int imsg_compose(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 197                  pid_t pid, int fd, const void *data, uint16_t datalen)
 198 {
 199         struct ibuf *wbuf;
 200
 201         if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
 202                 return (-1);
 203
 204         if (imsg_add(wbuf, data, datalen) == -1)
 205                 return (-1);
 206
 207         wbuf->fd = fd;
 208
 209         imsg_close(ibuf, wbuf);
 210
 211         return (1);
 212 }
 213
 214 int imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 215                   pid_t pid, int fd, const struct iovec *iov, int iovcnt)
 216 {
 217         struct ibuf *wbuf;
 218         int i, datalen = 0;
 219
 220         for (i = 0; i < iovcnt; i++)
 221                 datalen += iov[i].iov_len;
 222
 223         if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
 224                 return (-1);
 225
 226         for (i = 0; i < iovcnt; i++)
 227                 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
 228                         return (-1);
 229
 230         wbuf->fd = fd;
 231
 232         imsg_close(ibuf, wbuf);
 233
 234         return (1);
 235 }
 236
 237 /* ARGSUSED */
 238 struct ibuf *imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 239                          pid_t pid, uint16_t datalen)
 240 {
 241         struct ibuf *wbuf;
 242         struct imsg_hdr hdr;
 243
 244         memset(&hdr, 0x00, IMSG_HEADER_SIZE);
 245
 246         datalen += IMSG_HEADER_SIZE;
 247         if (datalen > MAX_IMSGSIZE) {
 248                 errno = ERANGE;
 249                 return (NULL);
 250         }
 251
 252         hdr.type = type;
 253         hdr.flags = 0;
 254         hdr.peerid = peerid;
 255         if ((hdr.pid = pid) == 0)
 256                 hdr.pid = ibuf->pid;
 257         if ((wbuf = ibuf_dynamic(datalen, MAX_IMSGSIZE)) == NULL) {
 258                 return (NULL);
 259         }
 260         if (imsg_add(wbuf, &hdr, sizeof(hdr)) == -1)
 261                 return (NULL);
 262
 263         return (wbuf);
 264 }
 265
 266 int imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
 267 {
 268         if (datalen)
 269                 if (ibuf_add(msg, data, datalen) == -1) {
 270                         ibuf_free(msg);
 271                         return (-1);
 272                 }
 273         return (datalen);
 274 }
 275
 276 void imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
 277 {
 278         struct imsg_hdr *hdr;
 279
 280         hdr = (struct imsg_hdr *)msg->buf;
 281
 282         hdr->flags &= ~IMSGF_HASFD;
 283         if (msg->fd != -1)
 284                 hdr->flags |= IMSGF_HASFD;
 285
 286         hdr->len = (uint16_t)msg->wpos;
 287
 288         ibuf_close(&ibuf->w, msg);
 289 }
 290
 291 void imsg_free(struct imsg *imsg)
 292 {
 293         free(imsg->data);
 294 }
 295
 296 int imsg_get_fd(struct imsgbuf *ibuf)
 297 {
 298         int fd;
 299         struct imsg_fd *ifd;
 300
 301         if ((ifd = TAILQ_FIRST(&ibuf->fds)) == NULL)
 302                 return (-1);
 303
 304         fd = ifd->fd;
 305         TAILQ_REMOVE(&ibuf->fds, ifd, entry);
 306         free(ifd);
 307
 308         return (fd);
 309 }
 310
 311 int imsg_flush(struct imsgbuf *ibuf)
 312 {
 313         while (ibuf->w.queued)
 314                 if (msgbuf_write(&ibuf->w) <= 0)
 315                         return (-1);
 316         return (0);
 317 }
 318
 319 void imsg_clear(struct imsgbuf *ibuf)
 320 {
 321         int fd;
 322
 323         msgbuf_clear(&ibuf->w);
 324         while ((fd = imsg_get_fd(ibuf)) != -1)
 325                 close(fd);
 326 }