contrib/ivshmem-client/ivshmem-client.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
   9 #include "qemu/osdep.h"
  10 #include <sys/socket.h>
  11 #include <sys/un.h>
  12
  13 #include "qemu-common.h"
  14 #include "qemu/queue.h"
  15
  16 #include "ivshmem-client.h"
  17
  18 /* log a message on stdout if verbose=1 */
  19 #define IVSHMEM_CLIENT_DEBUG(client, fmt, ...) do { \
  20         if ((client)->verbose) {         \
  21             printf(fmt, ## __VA_ARGS__); \
  22         }                                \
  23     } while (0)
  24
  25 /* read message from the unix socket */
  26 static int
  27 ivshmem_client_read_one_msg(IvshmemClient *client, int64_t *index, int *fd)
  28 {
  29     int ret;
  30     struct msghdr msg;
  31     struct iovec iov[1];
  32     union {
  33         struct cmsghdr cmsg;
  34         char control[CMSG_SPACE(sizeof(int))];
  35     } msg_control;
  36     struct cmsghdr *cmsg;
  37
  38     iov[0].iov_base = index;
  39     iov[0].iov_len = sizeof(*index);
  40
  41     memset(&msg, 0, sizeof(msg));
  42     msg.msg_iov = iov;
  43     msg.msg_iovlen = 1;
  44     msg.msg_control = &msg_control;
  45     msg.msg_controllen = sizeof(msg_control);
  46
  47     ret = recvmsg(client->sock_fd, &msg, 0);
  48     if (ret < sizeof(*index)) {
  49         IVSHMEM_CLIENT_DEBUG(client, "cannot read message: %s\n",
  50                              strerror(errno));
  51         return -1;
  52     }
  53     if (ret == 0) {
  54         IVSHMEM_CLIENT_DEBUG(client, "lost connection to server\n");
  55         return -1;
  56     }
  57
  58     *index = GINT64_FROM_LE(*index);
  59     *fd = -1;
  60
  61     for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
  62
  63         if (cmsg->cmsg_len != CMSG_LEN(sizeof(int)) ||
  64             cmsg->cmsg_level != SOL_SOCKET ||
  65             cmsg->cmsg_type != SCM_RIGHTS) {
  66             continue;
  67         }
  68
  69         memcpy(fd, CMSG_DATA(cmsg), sizeof(*fd));
  70     }
  71
  72     return 0;
  73 }
  74
  75 /* free a peer when the server advertises a disconnection or when the
  76  * client is freed */
  77 static void
  78 ivshmem_client_free_peer(IvshmemClient *client, IvshmemClientPeer *peer)
  79 {
  80     unsigned vector;
  81
  82     QTAILQ_REMOVE(&client->peer_list, peer, next);
  83     for (vector = 0; vector < peer->vectors_count; vector++) {
  84         close(peer->vectors[vector]);
  85     }
  86
  87     g_free(peer);
  88 }
  89
  90 /* handle message coming from server (new peer, new vectors) */
  91 static int
  92 ivshmem_client_handle_server_msg(IvshmemClient *client)
  93 {
  94     IvshmemClientPeer *peer;
  95     int64_t peer_id;
  96     int ret, fd;
  97
  98     ret = ivshmem_client_read_one_msg(client, &peer_id, &fd);
  99     if (ret < 0) {
 100         return -1;
 101     }
 102
 103     /* can return a peer or the local client */
 104     peer = ivshmem_client_search_peer(client, peer_id);
 105
 106     /* delete peer */
 107     if (fd == -1) {
 108
 109         if (peer == NULL || peer == &client->local) {
 110             IVSHMEM_CLIENT_DEBUG(client, "receive delete for invalid "
 111                                  "peer %" PRId64 "\n", peer_id);
 112             return -1;
 113         }
 114
 115         IVSHMEM_CLIENT_DEBUG(client, "delete peer id = %" PRId64 "\n", peer_id);
 116         ivshmem_client_free_peer(client, peer);
 117         return 0;
 118     }
 119
 120     /* new peer */
 121     if (peer == NULL) {
 122         peer = g_malloc0(sizeof(*peer));
 123         peer->id = peer_id;
 124         peer->vectors_count = 0;
 125         QTAILQ_INSERT_TAIL(&client->peer_list, peer, next);
 126         IVSHMEM_CLIENT_DEBUG(client, "new peer id = %" PRId64 "\n", peer_id);
 127     }
 128
 129     /* new vector */
 130     IVSHMEM_CLIENT_DEBUG(client, "  new vector %d (fd=%d) for peer id %"
 131                          PRId64 "\n", peer->vectors_count, fd, peer->id);
 132     if (peer->vectors_count >= G_N_ELEMENTS(peer->vectors)) {
 133         IVSHMEM_CLIENT_DEBUG(client, "Too many vectors received, failing");
 134         return -1;
 135     }
 136
 137     peer->vectors[peer->vectors_count] = fd;
 138     peer->vectors_count++;
 139
 140     return 0;
 141 }
 142
 143 /* init a new ivshmem client */
 144 int
 145 ivshmem_client_init(IvshmemClient *client, const char *unix_sock_path,
 146                     IvshmemClientNotifCb notif_cb, void *notif_arg,
 147                     bool verbose)
 148 {
 149     int ret;
 150     unsigned i;
 151
 152     memset(client, 0, sizeof(*client));
 153
 154     ret = snprintf(client->unix_sock_path, sizeof(client->unix_sock_path),
 155                    "%s", unix_sock_path);
 156
 157     if (ret < 0 || ret >= sizeof(client->unix_sock_path)) {
 158         IVSHMEM_CLIENT_DEBUG(client, "could not copy unix socket path\n");
 159         return -1;
 160     }
 161
 162     for (i = 0; i < IVSHMEM_CLIENT_MAX_VECTORS; i++) {
 163         client->local.vectors[i] = -1;
 164     }
 165
 166     QTAILQ_INIT(&client->peer_list);
 167     client->local.id = -1;
 168
 169     client->notif_cb = notif_cb;
 170     client->notif_arg = notif_arg;
 171     client->verbose = verbose;
 172     client->shm_fd = -1;
 173     client->sock_fd = -1;
 174
 175     return 0;
 176 }
 177
 178 /* create and connect to the unix socket */
 179 int
 180 ivshmem_client_connect(IvshmemClient *client)
 181 {
 182     struct sockaddr_un sun;
 183     int fd, ret;
 184     int64_t tmp;
 185
 186     IVSHMEM_CLIENT_DEBUG(client, "connect to client %s\n",
 187                          client->unix_sock_path);
 188
 189     client->sock_fd = socket(AF_UNIX, SOCK_STREAM, 0);
 190     if (client->sock_fd < 0) {
 191         IVSHMEM_CLIENT_DEBUG(client, "cannot create socket: %s\n",
 192                              strerror(errno));
 193         return -1;
 194     }
 195
 196     sun.sun_family = AF_UNIX;
 197     ret = snprintf(sun.sun_path, sizeof(sun.sun_path), "%s",
 198                    client->unix_sock_path);
 199     if (ret < 0 || ret >= sizeof(sun.sun_path)) {
 200         IVSHMEM_CLIENT_DEBUG(client, "could not copy unix socket path\n");
 201         goto err_close;
 202     }
 203
 204     if (connect(client->sock_fd, (struct sockaddr *)&sun, sizeof(sun)) < 0) {
 205         IVSHMEM_CLIENT_DEBUG(client, "cannot connect to %s: %s\n", sun.sun_path,
 206                              strerror(errno));
 207         goto err_close;
 208     }
 209
 210     /* first, we expect a protocol version */
 211     if (ivshmem_client_read_one_msg(client, &tmp, &fd) < 0 ||
 212         (tmp != IVSHMEM_PROTOCOL_VERSION) || fd != -1) {
 213         IVSHMEM_CLIENT_DEBUG(client, "cannot read from server\n");
 214         goto err_close;
 215     }
 216
 217     /* then, we expect our index + a fd == -1 */
 218     if (ivshmem_client_read_one_msg(client, &client->local.id, &fd) < 0 ||
 219         client->local.id < 0 || fd != -1) {
 220         IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (2)\n");
 221         goto err_close;
 222     }
 223     IVSHMEM_CLIENT_DEBUG(client, "our_id=%" PRId64 "\n", client->local.id);
 224
 225     /* now, we expect shared mem fd + a -1 index, note that shm fd
 226      * is not used */
 227     if (ivshmem_client_read_one_msg(client, &tmp, &fd) < 0 ||
 228         tmp != -1 || fd < 0) {
 229         if (fd >= 0) {
 230             close(fd);
 231         }
 232         IVSHMEM_CLIENT_DEBUG(client, "cannot read from server (3)\n");
 233         goto err_close;
 234     }
 235     client->shm_fd = fd;
 236     IVSHMEM_CLIENT_DEBUG(client, "shm_fd=%d\n", fd);
 237
 238     return 0;
 239
 240 err_close:
 241     close(client->sock_fd);
 242     client->sock_fd = -1;
 243     return -1;
 244 }
 245
 246 /* close connection to the server, and free all peer structures */
 247 void
 248 ivshmem_client_close(IvshmemClient *client)
 249 {
 250     IvshmemClientPeer *peer;
 251     unsigned i;
 252
 253     IVSHMEM_CLIENT_DEBUG(client, "close client\n");
 254
 255     while ((peer = QTAILQ_FIRST(&client->peer_list)) != NULL) {
 256         ivshmem_client_free_peer(client, peer);
 257     }
 258
 259     close(client->shm_fd);
 260     client->shm_fd = -1;
 261     close(client->sock_fd);
 262     client->sock_fd = -1;
 263     client->local.id = -1;
 264     for (i = 0; i < IVSHMEM_CLIENT_MAX_VECTORS; i++) {
 265         close(client->local.vectors[i]);
 266         client->local.vectors[i] = -1;
 267     }
 268     client->local.vectors_count = 0;
 269 }
 270
 271 /* get the fd_set according to the unix socket and peer list */
 272 void
 273 ivshmem_client_get_fds(const IvshmemClient *client, fd_set *fds, int *maxfd)
 274 {
 275     int fd;
 276     unsigned vector;
 277
 278     FD_SET(client->sock_fd, fds);
 279     if (client->sock_fd >= *maxfd) {
 280         *maxfd = client->sock_fd + 1;
 281     }
 282
 283     for (vector = 0; vector < client->local.vectors_count; vector++) {
 284         fd = client->local.vectors[vector];
 285         FD_SET(fd, fds);
 286         if (fd >= *maxfd) {
 287             *maxfd = fd + 1;
 288         }
 289     }
 290 }
 291
 292 /* handle events from eventfd: just print a message on notification */
 293 static int
 294 ivshmem_client_handle_event(IvshmemClient *client, const fd_set *cur, int maxfd)
 295 {
 296     IvshmemClientPeer *peer;
 297     uint64_t kick;
 298     unsigned i;
 299     int ret;
 300
 301     peer = &client->local;
 302
 303     for (i = 0; i < peer->vectors_count; i++) {
 304         if (peer->vectors[i] >= maxfd || !FD_ISSET(peer->vectors[i], cur)) {
 305             continue;
 306         }
 307
 308         ret = read(peer->vectors[i], &kick, sizeof(kick));
 309         if (ret < 0) {
 310             return ret;
 311         }
 312         if (ret != sizeof(kick)) {
 313             IVSHMEM_CLIENT_DEBUG(client, "invalid read size = %d\n", ret);
 314             errno = EINVAL;
 315             return -1;
 316         }
 317         IVSHMEM_CLIENT_DEBUG(client, "received event on fd %d vector %d: %"
 318                              PRIu64 "\n", peer->vectors[i], i, kick);
 319         if (client->notif_cb != NULL) {
 320             client->notif_cb(client, peer, i, client->notif_arg);
 321         }
 322     }
 323
 324     return 0;
 325 }
 326
 327 /* read and handle new messages on the given fd_set */
 328 int
 329 ivshmem_client_handle_fds(IvshmemClient *client, fd_set *fds, int maxfd)
 330 {
 331     if (client->sock_fd < maxfd && FD_ISSET(client->sock_fd, fds) &&
 332         ivshmem_client_handle_server_msg(client) < 0 && errno != EINTR) {
 333         IVSHMEM_CLIENT_DEBUG(client, "ivshmem_client_handle_server_msg() "
 334                              "failed\n");
 335         return -1;
 336     } else if (ivshmem_client_handle_event(client, fds, maxfd) < 0 &&
 337                errno != EINTR) {
 338         IVSHMEM_CLIENT_DEBUG(client, "ivshmem_client_handle_event() failed\n");
 339         return -1;
 340     }
 341
 342     return 0;
 343 }
 344
 345 /* send a notification on a vector of a peer */
 346 int
 347 ivshmem_client_notify(const IvshmemClient *client,
 348                       const IvshmemClientPeer *peer, unsigned vector)
 349 {
 350     uint64_t kick;
 351     int fd;
 352
 353     if (vector >= peer->vectors_count) {
 354         IVSHMEM_CLIENT_DEBUG(client, "invalid vector %u on peer %" PRId64 "\n",
 355                              vector, peer->id);
 356         return -1;
 357     }
 358     fd = peer->vectors[vector];
 359     IVSHMEM_CLIENT_DEBUG(client, "notify peer %" PRId64
 360                          " on vector %d, fd %d\n", peer->id, vector, fd);
 361
 362     kick = 1;
 363     if (write(fd, &kick, sizeof(kick)) != sizeof(kick)) {
 364         fprintf(stderr, "could not write to %d: %s\n", peer->vectors[vector],
 365                 strerror(errno));
 366         return -1;
 367     }
 368     return 0;
 369 }
 370
 371 /* send a notification to all vectors of a peer */
 372 int
 373 ivshmem_client_notify_all_vects(const IvshmemClient *client,
 374                                 const IvshmemClientPeer *peer)
 375 {
 376     unsigned vector;
 377     int ret = 0;
 378
 379     for (vector = 0; vector < peer->vectors_count; vector++) {
 380         if (ivshmem_client_notify(client, peer, vector) < 0) {
 381             ret = -1;
 382         }
 383     }
 384
 385     return ret;
 386 }
 387
 388 /* send a notification to all peers */
 389 int
 390 ivshmem_client_notify_broadcast(const IvshmemClient *client)
 391 {
 392     IvshmemClientPeer *peer;
 393     int ret = 0;
 394
 395     QTAILQ_FOREACH(peer, &client->peer_list, next) {
 396         if (ivshmem_client_notify_all_vects(client, peer) < 0) {
 397             ret = -1;
 398         }
 399     }
 400
 401     return ret;
 402 }
 403
 404 /* lookup peer from its id */
 405 IvshmemClientPeer *
 406 ivshmem_client_search_peer(IvshmemClient *client, int64_t peer_id)
 407 {
 408     IvshmemClientPeer *peer;
 409
 410     if (peer_id == client->local.id) {
 411         return &client->local;
 412     }
 413
 414     QTAILQ_FOREACH(peer, &client->peer_list, next) {
 415         if (peer->id == peer_id) {
 416             return peer;
 417         }
 418     }
 419     return NULL;
 420 }
 421
 422 /* dump our info, the list of peers their vectors on stdout */
 423 void
 424 ivshmem_client_dump(const IvshmemClient *client)
 425 {
 426     const IvshmemClientPeer *peer;
 427     unsigned vector;
 428
 429     /* dump local infos */
 430     peer = &client->local;
 431     printf("our_id = %" PRId64 "\n", peer->id);
 432     for (vector = 0; vector < peer->vectors_count; vector++) {
 433         printf("  vector %d is enabled (fd=%d)\n", vector,
 434                peer->vectors[vector]);
 435     }
 436
 437     /* dump peers */
 438     QTAILQ_FOREACH(peer, &client->peer_list, next) {
 439         printf("peer_id = %" PRId64 "\n", peer->id);
 440
 441         for (vector = 0; vector < peer->vectors_count; vector++) {
 442             printf("  vector %d is enabled (fd=%d)\n", vector,
 443                    peer->vectors[vector]);
 444         }
 445     }
 446 }