contrib/ivshmem-server/ivshmem-server.c

   1 /*
   2  * Copyright 6WIND S.A., 2014
   3  *
   4  * This work is licensed under the terms of the GNU GPL, version 2 or
   5  * (at your option) any later version.  See the COPYING file in the
   6  * top-level directory.
   7  */
   8 #include "qemu/osdep.h"
   9 #include "qemu-common.h"
  10 #include "qemu/sockets.h"
  11
  12 #include <sys/mman.h>
  13 #include <sys/socket.h>
  14 #include <sys/un.h>
  15
  16 #include "ivshmem-server.h"
  17
  18 /* log a message on stdout if verbose=1 */
  19 #define IVSHMEM_SERVER_DEBUG(server, fmt, ...) do { \
  20         if ((server)->verbose) {         \
  21             printf(fmt, ## __VA_ARGS__); \
  22         }                                \
  23     } while (0)
  24
  25 /** maximum size of a huge page, used by ivshmem_server_ftruncate() */
  26 #define IVSHMEM_SERVER_MAX_HUGEPAGE_SIZE (1024 * 1024 * 1024)
  27
  28 /** default listen backlog (number of sockets not accepted) */
  29 #define IVSHMEM_SERVER_LISTEN_BACKLOG 10
  30
  31 /* send message to a client unix socket */
  32 static int
  33 ivshmem_server_send_one_msg(int sock_fd, int64_t peer_id, int fd)
  34 {
  35     int ret;
  36     struct msghdr msg;
  37     struct iovec iov[1];
  38     union {
  39         struct cmsghdr cmsg;
  40         char control[CMSG_SPACE(sizeof(int))];
  41     } msg_control;
  42     struct cmsghdr *cmsg;
  43
  44     peer_id = GINT64_TO_LE(peer_id);
  45     iov[0].iov_base = &peer_id;
  46     iov[0].iov_len = sizeof(peer_id);
  47
  48     memset(&msg, 0, sizeof(msg));
  49     msg.msg_iov = iov;
  50     msg.msg_iovlen = 1;
  51
  52     /* if fd is specified, add it in a cmsg */
  53     if (fd >= 0) {
  54         memset(&msg_control, 0, sizeof(msg_control));
  55         msg.msg_control = &msg_control;
  56         msg.msg_controllen = sizeof(msg_control);
  57         cmsg = CMSG_FIRSTHDR(&msg);
  58         cmsg->cmsg_level = SOL_SOCKET;
  59         cmsg->cmsg_type = SCM_RIGHTS;
  60         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
  61         memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
  62     }
  63
  64     ret = sendmsg(sock_fd, &msg, 0);
  65     if (ret <= 0) {
  66         return -1;
  67     }
  68
  69     return 0;
  70 }
  71
  72 /* free a peer when the server advertises a disconnection or when the
  73  * server is freed */
  74 static void
  75 ivshmem_server_free_peer(IvshmemServer *server, IvshmemServerPeer *peer)
  76 {
  77     unsigned vector;
  78     IvshmemServerPeer *other_peer;
  79
  80     IVSHMEM_SERVER_DEBUG(server, "free peer %" PRId64 "\n", peer->id);
  81     close(peer->sock_fd);
  82     QTAILQ_REMOVE(&server->peer_list, peer, next);
  83
  84     /* advertise the deletion to other peers */
  85     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
  86         ivshmem_server_send_one_msg(other_peer->sock_fd, peer->id, -1);
  87     }
  88
  89     for (vector = 0; vector < peer->vectors_count; vector++) {
  90         event_notifier_cleanup(&peer->vectors[vector]);
  91     }
  92
  93     g_free(peer);
  94 }
  95
  96 /* send the peer id and the shm_fd just after a new client connection */
  97 static int
  98 ivshmem_server_send_initial_info(IvshmemServer *server, IvshmemServerPeer *peer)
  99 {
 100     int ret;
 101
 102     /* send our protocol version first */
 103     ret = ivshmem_server_send_one_msg(peer->sock_fd, IVSHMEM_PROTOCOL_VERSION,
 104                                       -1);
 105     if (ret < 0) {
 106         IVSHMEM_SERVER_DEBUG(server, "cannot send version: %s\n",
 107                              strerror(errno));
 108         return -1;
 109     }
 110
 111     /* send the peer id to the client */
 112     ret = ivshmem_server_send_one_msg(peer->sock_fd, peer->id, -1);
 113     if (ret < 0) {
 114         IVSHMEM_SERVER_DEBUG(server, "cannot send peer id: %s\n",
 115                              strerror(errno));
 116         return -1;
 117     }
 118
 119     /* send the shm_fd */
 120     ret = ivshmem_server_send_one_msg(peer->sock_fd, -1, server->shm_fd);
 121     if (ret < 0) {
 122         IVSHMEM_SERVER_DEBUG(server, "cannot send shm fd: %s\n",
 123                              strerror(errno));
 124         return -1;
 125     }
 126
 127     return 0;
 128 }
 129
 130 /* handle message on listening unix socket (new client connection) */
 131 static int
 132 ivshmem_server_handle_new_conn(IvshmemServer *server)
 133 {
 134     IvshmemServerPeer *peer, *other_peer;
 135     struct sockaddr_un unaddr;
 136     socklen_t unaddr_len;
 137     int newfd;
 138     unsigned i;
 139
 140     /* accept the incoming connection */
 141     unaddr_len = sizeof(unaddr);
 142     newfd = qemu_accept(server->sock_fd,
 143                         (struct sockaddr *)&unaddr, &unaddr_len);
 144
 145     if (newfd < 0) {
 146         IVSHMEM_SERVER_DEBUG(server, "cannot accept() %s\n", strerror(errno));
 147         return -1;
 148     }
 149
 150     qemu_set_nonblock(newfd);
 151     IVSHMEM_SERVER_DEBUG(server, "accept()=%d\n", newfd);
 152
 153     /* allocate new structure for this peer */
 154     peer = g_malloc0(sizeof(*peer));
 155     peer->sock_fd = newfd;
 156
 157     /* get an unused peer id */
 158     /* XXX: this could use id allocation such as Linux IDA, or simply
 159      * a free-list */
 160     for (i = 0; i < G_MAXUINT16; i++) {
 161         if (ivshmem_server_search_peer(server, server->cur_id) == NULL) {
 162             break;
 163         }
 164         server->cur_id++;
 165     }
 166     if (i == G_MAXUINT16) {
 167         IVSHMEM_SERVER_DEBUG(server, "cannot allocate new client id\n");
 168         close(newfd);
 169         g_free(peer);
 170         return -1;
 171     }
 172     peer->id = server->cur_id++;
 173
 174     /* create eventfd, one per vector */
 175     peer->vectors_count = server->n_vectors;
 176     for (i = 0; i < peer->vectors_count; i++) {
 177         if (event_notifier_init(&peer->vectors[i], FALSE) < 0) {
 178             IVSHMEM_SERVER_DEBUG(server, "cannot create eventfd\n");
 179             goto fail;
 180         }
 181     }
 182
 183     /* send peer id and shm fd */
 184     if (ivshmem_server_send_initial_info(server, peer) < 0) {
 185         IVSHMEM_SERVER_DEBUG(server, "cannot send initial info\n");
 186         goto fail;
 187     }
 188
 189     /* advertise the new peer to others */
 190     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
 191         for (i = 0; i < peer->vectors_count; i++) {
 192             ivshmem_server_send_one_msg(other_peer->sock_fd, peer->id,
 193                                         peer->vectors[i].wfd);
 194         }
 195     }
 196
 197     /* advertise the other peers to the new one */
 198     QTAILQ_FOREACH(other_peer, &server->peer_list, next) {
 199         for (i = 0; i < peer->vectors_count; i++) {
 200             ivshmem_server_send_one_msg(peer->sock_fd, other_peer->id,
 201                                         other_peer->vectors[i].wfd);
 202         }
 203     }
 204
 205     /* advertise the new peer to itself */
 206     for (i = 0; i < peer->vectors_count; i++) {
 207         ivshmem_server_send_one_msg(peer->sock_fd, peer->id,
 208                                     event_notifier_get_fd(&peer->vectors[i]));
 209     }
 210
 211     QTAILQ_INSERT_TAIL(&server->peer_list, peer, next);
 212     IVSHMEM_SERVER_DEBUG(server, "new peer id = %" PRId64 "\n",
 213                          peer->id);
 214     return 0;
 215
 216 fail:
 217     while (i--) {
 218         event_notifier_cleanup(&peer->vectors[i]);
 219     }
 220     close(newfd);
 221     g_free(peer);
 222     return -1;
 223 }
 224
 225 /* Try to ftruncate a file to next power of 2 of shmsize.
 226  * If it fails; all power of 2 above shmsize are tested until
 227  * we reach the maximum huge page size. This is useful
 228  * if the shm file is in a hugetlbfs that cannot be truncated to the
 229  * shm_size value. */
 230 static int
 231 ivshmem_server_ftruncate(int fd, unsigned shmsize)
 232 {
 233     int ret;
 234     struct stat mapstat;
 235
 236     /* align shmsize to next power of 2 */
 237     shmsize = pow2ceil(shmsize);
 238
 239     if (fstat(fd, &mapstat) != -1 && mapstat.st_size == shmsize) {
 240         return 0;
 241     }
 242
 243     while (shmsize <= IVSHMEM_SERVER_MAX_HUGEPAGE_SIZE) {
 244         ret = ftruncate(fd, shmsize);
 245         if (ret == 0) {
 246             return ret;
 247         }
 248         shmsize *= 2;
 249     }
 250
 251     return -1;
 252 }
 253
 254 /* Init a new ivshmem server */
 255 int
 256 ivshmem_server_init(IvshmemServer *server, const char *unix_sock_path,
 257                     const char *shm_path, bool use_shm_open,
 258                     size_t shm_size, unsigned n_vectors,
 259                     bool verbose)
 260 {
 261     int ret;
 262
 263     memset(server, 0, sizeof(*server));
 264     server->verbose = verbose;
 265
 266     ret = snprintf(server->unix_sock_path, sizeof(server->unix_sock_path),
 267                    "%s", unix_sock_path);
 268     if (ret < 0 || ret >= sizeof(server->unix_sock_path)) {
 269         IVSHMEM_SERVER_DEBUG(server, "could not copy unix socket path\n");
 270         return -1;
 271     }
 272     ret = snprintf(server->shm_path, sizeof(server->shm_path),
 273                    "%s", shm_path);
 274     if (ret < 0 || ret >= sizeof(server->shm_path)) {
 275         IVSHMEM_SERVER_DEBUG(server, "could not copy shm path\n");
 276         return -1;
 277     }
 278
 279     server->use_shm_open = use_shm_open;
 280     server->shm_size = shm_size;
 281     server->n_vectors = n_vectors;
 282
 283     QTAILQ_INIT(&server->peer_list);
 284
 285     return 0;
 286 }
 287
 288 /* open shm, create and bind to the unix socket */
 289 int
 290 ivshmem_server_start(IvshmemServer *server)
 291 {
 292     struct sockaddr_un sun;
 293     int shm_fd, sock_fd, ret;
 294
 295     /* open shm file */
 296     if (server->use_shm_open) {
 297         IVSHMEM_SERVER_DEBUG(server, "Using POSIX shared memory: %s\n",
 298                              server->shm_path);
 299         shm_fd = shm_open(server->shm_path, O_CREAT | O_RDWR, S_IRWXU);
 300     } else {
 301         gchar *filename = g_strdup_printf("%s/ivshmem.XXXXXX", server->shm_path);
 302         IVSHMEM_SERVER_DEBUG(server, "Using file-backed shared memory: %s\n",
 303                              server->shm_path);
 304         shm_fd = mkstemp(filename);
 305         unlink(filename);
 306         g_free(filename);
 307     }
 308
 309     if (shm_fd < 0) {
 310         fprintf(stderr, "cannot open shm file %s: %s\n", server->shm_path,
 311                 strerror(errno));
 312         return -1;
 313     }
 314     if (ivshmem_server_ftruncate(shm_fd, server->shm_size) < 0) {
 315         fprintf(stderr, "ftruncate(%s) failed: %s\n", server->shm_path,
 316                 strerror(errno));
 317         goto err_close_shm;
 318     }
 319
 320     IVSHMEM_SERVER_DEBUG(server, "create & bind socket %s\n",
 321                          server->unix_sock_path);
 322
 323     /* create the unix listening socket */
 324     sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 325     if (sock_fd < 0) {
 326         IVSHMEM_SERVER_DEBUG(server, "cannot create socket: %s\n",
 327                              strerror(errno));
 328         goto err_close_shm;
 329     }
 330
 331     sun.sun_family = AF_UNIX;
 332     ret = snprintf(sun.sun_path, sizeof(sun.sun_path), "%s",
 333                    server->unix_sock_path);
 334     if (ret < 0 || ret >= sizeof(sun.sun_path)) {
 335         IVSHMEM_SERVER_DEBUG(server, "could not copy unix socket path\n");
 336         goto err_close_sock;
 337     }
 338     if (bind(sock_fd, (struct sockaddr *)&sun, sizeof(sun)) < 0) {
 339         IVSHMEM_SERVER_DEBUG(server, "cannot connect to %s: %s\n", sun.sun_path,
 340                              strerror(errno));
 341         goto err_close_sock;
 342     }
 343
 344     if (listen(sock_fd, IVSHMEM_SERVER_LISTEN_BACKLOG) < 0) {
 345         IVSHMEM_SERVER_DEBUG(server, "listen() failed: %s\n", strerror(errno));
 346         goto err_close_sock;
 347     }
 348
 349     server->sock_fd = sock_fd;
 350     server->shm_fd = shm_fd;
 351
 352     return 0;
 353
 354 err_close_sock:
 355     close(sock_fd);
 356 err_close_shm:
 357     close(shm_fd);
 358     return -1;
 359 }
 360
 361 /* close connections to clients, the unix socket and the shm fd */
 362 void
 363 ivshmem_server_close(IvshmemServer *server)
 364 {
 365     IvshmemServerPeer *peer, *npeer;
 366
 367     IVSHMEM_SERVER_DEBUG(server, "close server\n");
 368
 369     QTAILQ_FOREACH_SAFE(peer, &server->peer_list, next, npeer) {
 370         ivshmem_server_free_peer(server, peer);
 371     }
 372
 373     unlink(server->unix_sock_path);
 374     close(server->sock_fd);
 375     close(server->shm_fd);
 376     server->sock_fd = -1;
 377     server->shm_fd = -1;
 378 }
 379
 380 /* get the fd_set according to the unix socket and the peer list */
 381 void
 382 ivshmem_server_get_fds(const IvshmemServer *server, fd_set *fds, int *maxfd)
 383 {
 384     IvshmemServerPeer *peer;
 385
 386     if (server->sock_fd == -1) {
 387         return;
 388     }
 389
 390     FD_SET(server->sock_fd, fds);
 391     if (server->sock_fd >= *maxfd) {
 392         *maxfd = server->sock_fd + 1;
 393     }
 394
 395     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 396         FD_SET(peer->sock_fd, fds);
 397         if (peer->sock_fd >= *maxfd) {
 398             *maxfd = peer->sock_fd + 1;
 399         }
 400     }
 401 }
 402
 403 /* process incoming messages on the sockets in fd_set */
 404 int
 405 ivshmem_server_handle_fds(IvshmemServer *server, fd_set *fds, int maxfd)
 406 {
 407     IvshmemServerPeer *peer, *peer_next;
 408
 409     if (server->sock_fd < maxfd && FD_ISSET(server->sock_fd, fds) &&
 410         ivshmem_server_handle_new_conn(server) < 0 && errno != EINTR) {
 411         IVSHMEM_SERVER_DEBUG(server, "ivshmem_server_handle_new_conn() "
 412                              "failed\n");
 413         return -1;
 414     }
 415
 416     QTAILQ_FOREACH_SAFE(peer, &server->peer_list, next, peer_next) {
 417         /* any message from a peer socket result in a close() */
 418         IVSHMEM_SERVER_DEBUG(server, "peer->sock_fd=%d\n", peer->sock_fd);
 419         if (peer->sock_fd < maxfd && FD_ISSET(peer->sock_fd, fds)) {
 420             ivshmem_server_free_peer(server, peer);
 421         }
 422     }
 423
 424     return 0;
 425 }
 426
 427 /* lookup peer from its id */
 428 IvshmemServerPeer *
 429 ivshmem_server_search_peer(IvshmemServer *server, int64_t peer_id)
 430 {
 431     IvshmemServerPeer *peer;
 432
 433     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 434         if (peer->id == peer_id) {
 435             return peer;
 436         }
 437     }
 438     return NULL;
 439 }
 440
 441 /* dump our info, the list of peers their vectors on stdout */
 442 void
 443 ivshmem_server_dump(const IvshmemServer *server)
 444 {
 445     const IvshmemServerPeer *peer;
 446     unsigned vector;
 447
 448     /* dump peers */
 449     QTAILQ_FOREACH(peer, &server->peer_list, next) {
 450         printf("peer_id = %" PRId64 "\n", peer->id);
 451
 452         for (vector = 0; vector < peer->vectors_count; vector++) {
 453             printf("  vector %d is enabled (fd=%d)\n", vector,
 454                    event_notifier_get_fd(&peer->vectors[vector]));
 455         }
 456     }
 457 }