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 "memory.h"
  22 #include "queue.h"
  23 #include "imsg.h"
  24
  25 static int imsg_fd_overhead = 0;
  26
  27 static int imsg_get_fd(struct imsgbuf *);
  28
  29 #ifndef __OpenBSD__
  30 /*
  31  * The original code calls getdtablecount() which is OpenBSD specific. Use
  32  * available_fds() from OpenSMTPD instead.
  33  */
  34 static int available_fds(unsigned int n)
  35 {
  36         unsigned int i;
  37         int ret, fds[256];
  38
  39         if (n > (unsigned int)array_size(fds))
  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 imsg_init(struct imsgbuf *ibuf, int fd)
  63 {
  64         msgbuf_init(&ibuf->w);
  65         memset(&ibuf->r, 0, sizeof(ibuf->r));
  66         ibuf->fd = fd;
  67         ibuf->w.fd = fd;
  68         ibuf->pid = getpid();
  69         TAILQ_INIT(&ibuf->fds);
  70 }
  71
  72 ssize_t imsg_read(struct imsgbuf *ibuf)
  73 {
  74         struct msghdr msg;
  75         struct cmsghdr *cmsg;
  76         union {
  77                 struct cmsghdr hdr;
  78                 char buf[CMSG_SPACE(sizeof(int) * 1)];
  79         } cmsgbuf;
  80         struct iovec iov;
  81         ssize_t n;
  82         int fd;
  83         struct imsg_fd *ifd;
  84
  85         memset(&msg, 0, sizeof(msg));
  86         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
  87
  88         iov.iov_base = ibuf->r.buf + ibuf->r.wpos;
  89         iov.iov_len = sizeof(ibuf->r.buf) - ibuf->r.wpos;
  90         msg.msg_iov = &iov;
  91         msg.msg_iovlen = 1;
  92         msg.msg_control = &cmsgbuf.buf;
  93         msg.msg_controllen = sizeof(cmsgbuf.buf);
  94
  95         if ((ifd = calloc(1, sizeof(struct imsg_fd))) == NULL)
  96                 return -1;
  97
  98 again:
  99 #ifdef __OpenBSD__
 100         if (getdtablecount() + imsg_fd_overhead
 101                     + (int)((CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))
 102                             / sizeof(int))
 103             >= getdtablesize()) {
 104 #else
 105         if (available_fds(imsg_fd_overhead
 106                           + (CMSG_SPACE(sizeof(int)) - CMSG_SPACE(0))
 107                                     / sizeof(int))) {
 108 #endif
 109                 errno = EAGAIN;
 110                 free(ifd);
 111                 return -1;
 112         }
 113
 114         n = recvmsg(ibuf->fd, &msg, 0);
 115         if (n == -1) {
 116                 if (errno == EINTR)
 117                         goto again;
 118                 goto fail;
 119         }
 120
 121         ibuf->r.wpos += n;
 122
 123         for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL;
 124              cmsg = CMSG_NXTHDR(&msg, cmsg)) {
 125                 if (cmsg->cmsg_level == SOL_SOCKET
 126                     && cmsg->cmsg_type == SCM_RIGHTS) {
 127                         int i;
 128                         int j;
 129
 130                         /*
 131                          * We only accept one file descriptor.  Due to C
 132                          * padding rules, our control buffer might contain
 133                          * more than one fd, and we must close them.
 134                          */
 135                         j = ((char *)cmsg + cmsg->cmsg_len
 136                              - (char *)CMSG_DATA(cmsg))
 137                             / sizeof(int);
 138                         for (i = 0; i < j; i++) {
 139                                 fd = ((int *)CMSG_DATA(cmsg))[i];
 140                                 if (ifd != NULL) {
 141                                         ifd->fd = fd;
 142                                         TAILQ_INSERT_TAIL(&ibuf->fds, ifd,
 143                                                           entry);
 144                                         ifd = NULL;
 145                                 } else
 146                                         close(fd);
 147                         }
 148                 }
 149                 /* we do not handle other ctl data level */
 150         }
 151
 152 fail:
 153         free(ifd);
 154         return (n);
 155 }
 156
 157 ssize_t imsg_get(struct imsgbuf *ibuf, struct imsg *imsg)
 158 {
 159         size_t av, left, datalen;
 160
 161         av = ibuf->r.wpos;
 162
 163         if (IMSG_HEADER_SIZE > av)
 164                 return 0;
 165
 166         memcpy(&imsg->hdr, ibuf->r.buf, sizeof(imsg->hdr));
 167         if (imsg->hdr.len < IMSG_HEADER_SIZE || 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         if (imsg->data)
 186                 memcpy(imsg->data, ibuf->r.rptr, datalen);
 187
 188         if (imsg->hdr.len < av) {
 189                 left = av - imsg->hdr.len;
 190                 memmove(&ibuf->r.buf, ibuf->r.buf + imsg->hdr.len, left);
 191                 ibuf->r.wpos = left;
 192         } else
 193                 ibuf->r.wpos = 0;
 194
 195         return (datalen + IMSG_HEADER_SIZE);
 196 }
 197
 198 int imsg_compose(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 199                  pid_t pid, int fd, const void *data, uint16_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 imsg_composev(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 217                   pid_t pid, int fd, const struct iovec *iov, int iovcnt)
 218 {
 219         struct ibuf *wbuf;
 220         int i, datalen = 0;
 221
 222         for (i = 0; i < iovcnt; i++)
 223                 datalen += iov[i].iov_len;
 224
 225         if ((wbuf = imsg_create(ibuf, type, peerid, pid, datalen)) == NULL)
 226                 return -1;
 227
 228         for (i = 0; i < iovcnt; i++)
 229                 if (imsg_add(wbuf, iov[i].iov_base, iov[i].iov_len) == -1)
 230                         return -1;
 231
 232         wbuf->fd = fd;
 233
 234         imsg_close(ibuf, wbuf);
 235
 236         return 1;
 237 }
 238
 239 /* ARGSUSED */
 240 struct ibuf *imsg_create(struct imsgbuf *ibuf, uint32_t type, uint32_t peerid,
 241                          pid_t pid, uint16_t datalen)
 242 {
 243         struct ibuf *wbuf;
 244         struct imsg_hdr hdr;
 245
 246         memset(&hdr, 0x00, IMSG_HEADER_SIZE);
 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 imsg_add(struct ibuf *msg, const void *data, uint16_t datalen)
 269 {
 270         if (datalen)
 271                 if (ibuf_add(msg, data, datalen) == -1) {
 272                         ibuf_free(msg);
 273                         return -1;
 274                 }
 275         return (datalen);
 276 }
 277
 278 void imsg_close(struct imsgbuf *ibuf, struct ibuf *msg)
 279 {
 280         struct imsg_hdr *hdr;
 281
 282         hdr = (struct imsg_hdr *)msg->buf;
 283
 284         hdr->flags &= ~IMSGF_HASFD;
 285         if (msg->fd != -1)
 286                 hdr->flags |= IMSGF_HASFD;
 287
 288         hdr->len = (uint16_t)msg->wpos;
 289
 290         ibuf_close(&ibuf->w, msg);
 291 }
 292
 293 void imsg_free(struct imsg *imsg)
 294 {
 295         free(imsg->data);
 296 }
 297
 298 int imsg_get_fd(struct imsgbuf *ibuf)
 299 {
 300         int fd;
 301         struct imsg_fd *ifd;
 302
 303         if ((ifd = TAILQ_POP_FIRST(&ibuf->fds, entry)) == NULL)
 304                 return -1;
 305
 306         fd = ifd->fd;
 307         free(ifd);
 308
 309         return (fd);
 310 }
 311
 312 int imsg_flush(struct imsgbuf *ibuf)
 313 {
 314         while (ibuf->w.queued)
 315                 if (msgbuf_write(&ibuf->w) <= 0)
 316                         return -1;
 317         return 0;
 318 }
 319
 320 void imsg_clear(struct imsgbuf *ibuf)
 321 {
 322         int fd;
 323
 324         msgbuf_clear(&ibuf->w);
 325         while ((fd = imsg_get_fd(ibuf)) != -1)
 326                 close(fd);
 327 }