qemu-nbd.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu-common.h"
  20 #include "block_int.h"
  21 #include "nbd.h"
  22
  23 #include <stdarg.h>
  24 #include <stdio.h>
  25 #include <getopt.h>
  26 #include <err.h>
  27 #include <sys/types.h>
  28 #include <sys/socket.h>
  29 #include <netinet/in.h>
  30 #include <netinet/tcp.h>
  31 #include <arpa/inet.h>
  32 #include <signal.h>
  33 #include <libgen.h>
  34
  35 #define SOCKET_PATH    "/var/lock/qemu-nbd-%s"
  36
  37 #define NBD_BUFFER_SIZE (1024*1024)
  38
  39 static int verbose;
  40
  41 static void usage(const char *name)
  42 {
  43     printf(
  44 "Usage: %s [OPTIONS] FILE\n"
  45 "QEMU Disk Network Block Device Server\n"
  46 "\n"
  47 "  -p, --port=PORT      port to listen on (default `%d')\n"
  48 "  -o, --offset=OFFSET  offset into the image\n"
  49 "  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
  50 "  -k, --socket=PATH    path to the unix socket\n"
  51 "                       (default '"SOCKET_PATH"')\n"
  52 "  -r, --read-only      export read-only\n"
  53 "  -P, --partition=NUM  only expose partition NUM\n"
  54 "  -s, --snapshot       use snapshot file\n"
  55 "  -n, --nocache        disable host cache\n"
  56 "  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
  57 "  -d, --disconnect     disconnect the specified device\n"
  58 "  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
  59 "  -t, --persistent     don't exit on the last connection\n"
  60 "  -v, --verbose        display extra debugging information\n"
  61 "  -h, --help           display this help and exit\n"
  62 "  -V, --version        output version information and exit\n"
  63 "\n"
  64 "Report bugs to <anthony@codemonkey.ws>\n"
  65     , name, NBD_DEFAULT_PORT, "DEVICE");
  66 }
  67
  68 static void version(const char *name)
  69 {
  70     printf(
  71 "%s version 0.0.1\n"
  72 "Written by Anthony Liguori.\n"
  73 "\n"
  74 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
  75 "This is free software; see the source for copying conditions.  There is NO\n"
  76 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
  77     , name);
  78 }
  79
  80 struct partition_record
  81 {
  82     uint8_t bootable;
  83     uint8_t start_head;
  84     uint32_t start_cylinder;
  85     uint8_t start_sector;
  86     uint8_t system;
  87     uint8_t end_head;
  88     uint8_t end_cylinder;
  89     uint8_t end_sector;
  90     uint32_t start_sector_abs;
  91     uint32_t nb_sectors_abs;
  92 };
  93
  94 static void read_partition(uint8_t *p, struct partition_record *r)
  95 {
  96     r->bootable = p[0];
  97     r->start_head = p[1];
  98     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
  99     r->start_sector = p[2] & 0x3f;
 100     r->system = p[4];
 101     r->end_head = p[5];
 102     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 103     r->end_sector = p[6] & 0x3f;
 104     r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 105     r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 106 }
 107
 108 static int find_partition(BlockDriverState *bs, int partition,
 109                           off_t *offset, off_t *size)
 110 {
 111     struct partition_record mbr[4];
 112     uint8_t data[512];
 113     int i;
 114     int ext_partnum = 4;
 115     int ret;
 116
 117     if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 118         errno = -ret;
 119         err(EXIT_FAILURE, "error while reading");
 120     }
 121
 122     if (data[510] != 0x55 || data[511] != 0xaa) {
 123         errno = -EINVAL;
 124         return -1;
 125     }
 126
 127     for (i = 0; i < 4; i++) {
 128         read_partition(&data[446 + 16 * i], &mbr[i]);
 129
 130         if (!mbr[i].nb_sectors_abs)
 131             continue;
 132
 133         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 134             struct partition_record ext[4];
 135             uint8_t data1[512];
 136             int j;
 137
 138             if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 139                 errno = -ret;
 140                 err(EXIT_FAILURE, "error while reading");
 141             }
 142
 143             for (j = 0; j < 4; j++) {
 144                 read_partition(&data1[446 + 16 * j], &ext[j]);
 145                 if (!ext[j].nb_sectors_abs)
 146                     continue;
 147
 148                 if ((ext_partnum + j + 1) == partition) {
 149                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 150                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 151                     return 0;
 152                 }
 153             }
 154             ext_partnum += 4;
 155         } else if ((i + 1) == partition) {
 156             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 157             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 158             return 0;
 159         }
 160     }
 161
 162     errno = -ENOENT;
 163     return -1;
 164 }
 165
 166 static void show_parts(const char *device)
 167 {
 168     if (fork() == 0) {
 169         int nbd;
 170
 171         /* linux just needs an open() to trigger
 172          * the partition table update
 173          * but remember to load the module with max_part != 0 :
 174          *     modprobe nbd max_part=63
 175          */
 176         nbd = open(device, O_RDWR);
 177         if (nbd != -1)
 178               close(nbd);
 179         exit(0);
 180     }
 181 }
 182
 183 int main(int argc, char **argv)
 184 {
 185     BlockDriverState *bs;
 186     off_t dev_offset = 0;
 187     off_t offset = 0;
 188     uint32_t nbdflags = 0;
 189     bool disconnect = false;
 190     const char *bindto = "0.0.0.0";
 191     int port = NBD_DEFAULT_PORT;
 192     struct sockaddr_in addr;
 193     socklen_t addr_len = sizeof(addr);
 194     off_t fd_size;
 195     char *device = NULL;
 196     char *socket = NULL;
 197     char sockpath[128];
 198     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:t";
 199     struct option lopt[] = {
 200         { "help", 0, NULL, 'h' },
 201         { "version", 0, NULL, 'V' },
 202         { "bind", 1, NULL, 'b' },
 203         { "port", 1, NULL, 'p' },
 204         { "socket", 1, NULL, 'k' },
 205         { "offset", 1, NULL, 'o' },
 206         { "read-only", 0, NULL, 'r' },
 207         { "partition", 1, NULL, 'P' },
 208         { "connect", 1, NULL, 'c' },
 209         { "disconnect", 0, NULL, 'd' },
 210         { "snapshot", 0, NULL, 's' },
 211         { "nocache", 0, NULL, 'n' },
 212         { "shared", 1, NULL, 'e' },
 213         { "persistent", 0, NULL, 't' },
 214         { "verbose", 0, NULL, 'v' },
 215         { NULL, 0, NULL, 0 }
 216     };
 217     int ch;
 218     int opt_ind = 0;
 219     int li;
 220     char *end;
 221     int flags = BDRV_O_RDWR;
 222     int partition = -1;
 223     int ret;
 224     int shared = 1;
 225     uint8_t *data;
 226     fd_set fds;
 227     int *sharing_fds;
 228     int fd;
 229     int i;
 230     int nb_fds = 0;
 231     int max_fd;
 232     int persistent = 0;
 233
 234     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 235         switch (ch) {
 236         case 's':
 237             flags |= BDRV_O_SNAPSHOT;
 238             break;
 239         case 'n':
 240             flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
 241             break;
 242         case 'b':
 243             bindto = optarg;
 244             break;
 245         case 'p':
 246             li = strtol(optarg, &end, 0);
 247             if (*end) {
 248                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 249             }
 250             if (li < 1 || li > 65535) {
 251                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 252             }
 253             port = (uint16_t)li;
 254             break;
 255         case 'o':
 256                 dev_offset = strtoll (optarg, &end, 0);
 257             if (*end) {
 258                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 259             }
 260             if (dev_offset < 0) {
 261                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 262             }
 263             break;
 264         case 'r':
 265             nbdflags |= NBD_FLAG_READ_ONLY;
 266             flags &= ~BDRV_O_RDWR;
 267             break;
 268         case 'P':
 269             partition = strtol(optarg, &end, 0);
 270             if (*end)
 271                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 272             if (partition < 1 || partition > 8)
 273                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 274             break;
 275         case 'k':
 276             socket = optarg;
 277             if (socket[0] != '/')
 278                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 279             break;
 280         case 'd':
 281             disconnect = true;
 282             break;
 283         case 'c':
 284             device = optarg;
 285             break;
 286         case 'e':
 287             shared = strtol(optarg, &end, 0);
 288             if (*end) {
 289                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 290             }
 291             if (shared < 1) {
 292                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 293             }
 294             break;
 295         case 't':
 296             persistent = 1;
 297             break;
 298         case 'v':
 299             verbose = 1;
 300             break;
 301         case 'V':
 302             version(argv[0]);
 303             exit(0);
 304             break;
 305         case 'h':
 306             usage(argv[0]);
 307             exit(0);
 308             break;
 309         case '?':
 310             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 311                  argv[0]);
 312         }
 313     }
 314
 315     if ((argc - optind) != 1) {
 316         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 317              "Try `%s --help' for more information.",
 318              argv[0]);
 319     }
 320
 321     if (disconnect) {
 322         fd = open(argv[optind], O_RDWR);
 323         if (fd == -1)
 324             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 325
 326         nbd_disconnect(fd);
 327
 328         close(fd);
 329
 330         printf("%s disconnected\n", argv[optind]);
 331
 332         return 0;
 333     }
 334
 335     bdrv_init();
 336
 337     bs = bdrv_new("hda");
 338
 339     if ((ret = bdrv_open(bs, argv[optind], flags, NULL)) < 0) {
 340         errno = -ret;
 341         err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);
 342     }
 343
 344     fd_size = bs->total_sectors * 512;
 345
 346     if (partition != -1 &&
 347         find_partition(bs, partition, &dev_offset, &fd_size))
 348         err(EXIT_FAILURE, "Could not find partition %d", partition);
 349
 350     if (device) {
 351         pid_t pid;
 352         int sock;
 353
 354         /* want to fail before daemonizing */
 355         if (access(device, R_OK|W_OK) == -1) {
 356             err(EXIT_FAILURE, "Could not access '%s'", device);
 357         }
 358
 359         if (!verbose) {
 360             /* detach client and server */
 361             if (qemu_daemon(0, 0) == -1) {
 362                 err(EXIT_FAILURE, "Failed to daemonize");
 363             }
 364         }
 365
 366         if (socket == NULL) {
 367             snprintf(sockpath, sizeof(sockpath), SOCKET_PATH,
 368                      basename(device));
 369             socket = sockpath;
 370         }
 371
 372         pid = fork();
 373         if (pid < 0)
 374             return 1;
 375         if (pid != 0) {
 376             off_t size;
 377             size_t blocksize;
 378
 379             ret = 0;
 380             bdrv_close(bs);
 381
 382             do {
 383                 sock = unix_socket_outgoing(socket);
 384                 if (sock == -1) {
 385                     if (errno != ENOENT && errno != ECONNREFUSED) {
 386                         ret = 1;
 387                         goto out;
 388                     }
 389                     sleep(1);   /* wait children */
 390                 }
 391             } while (sock == -1);
 392
 393             fd = open(device, O_RDWR);
 394             if (fd == -1) {
 395                 ret = 1;
 396                 goto out;
 397             }
 398
 399             ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 400                                         &size, &blocksize);
 401             if (ret == -1) {
 402                 ret = 1;
 403                 goto out;
 404             }
 405
 406             ret = nbd_init(fd, sock, nbdflags, size, blocksize);
 407             if (ret == -1) {
 408                 ret = 1;
 409                 goto out;
 410             }
 411
 412             printf("NBD device %s is now connected to file %s\n",
 413                     device, argv[optind]);
 414
 415             /* update partition table */
 416
 417             show_parts(device);
 418
 419             ret = nbd_client(fd);
 420             if (ret) {
 421                 ret = 1;
 422             }
 423             close(fd);
 424  out:
 425             kill(pid, SIGTERM);
 426             unlink(socket);
 427
 428             return ret;
 429         }
 430         /* children */
 431     }
 432
 433     sharing_fds = g_malloc((shared + 1) * sizeof(int));
 434
 435     if (socket) {
 436         sharing_fds[0] = unix_socket_incoming(socket);
 437     } else {
 438         sharing_fds[0] = tcp_socket_incoming(bindto, port);
 439     }
 440
 441     if (sharing_fds[0] == -1)
 442         return 1;
 443     max_fd = sharing_fds[0];
 444     nb_fds++;
 445
 446     data = qemu_blockalign(bs, NBD_BUFFER_SIZE);
 447     if (data == NULL)
 448         errx(EXIT_FAILURE, "Cannot allocate data buffer");
 449
 450     do {
 451
 452         FD_ZERO(&fds);
 453         for (i = 0; i < nb_fds; i++)
 454             FD_SET(sharing_fds[i], &fds);
 455
 456         ret = select(max_fd + 1, &fds, NULL, NULL, NULL);
 457         if (ret == -1)
 458             break;
 459
 460         if (FD_ISSET(sharing_fds[0], &fds))
 461             ret--;
 462         for (i = 1; i < nb_fds && ret; i++) {
 463             if (FD_ISSET(sharing_fds[i], &fds)) {
 464                 if (nbd_trip(bs, sharing_fds[i], fd_size, dev_offset,
 465                     &offset, nbdflags, data, NBD_BUFFER_SIZE) != 0) {
 466                     close(sharing_fds[i]);
 467                     nb_fds--;
 468                     sharing_fds[i] = sharing_fds[nb_fds];
 469                     i--;
 470                 }
 471                 ret--;
 472             }
 473         }
 474         /* new connection ? */
 475         if (FD_ISSET(sharing_fds[0], &fds)) {
 476             if (nb_fds < shared + 1) {
 477                 sharing_fds[nb_fds] = accept(sharing_fds[0],
 478                                              (struct sockaddr *)&addr,
 479                                              &addr_len);
 480                 if (sharing_fds[nb_fds] != -1 &&
 481                     nbd_negotiate(sharing_fds[nb_fds], fd_size, nbdflags) != -1) {
 482                         if (sharing_fds[nb_fds] > max_fd)
 483                             max_fd = sharing_fds[nb_fds];
 484                         nb_fds++;
 485                 }
 486             }
 487         }
 488     } while (persistent || nb_fds > 1);
 489     qemu_vfree(data);
 490
 491     close(sharing_fds[0]);
 492     bdrv_close(bs);
 493     g_free(sharing_fds);
 494     if (socket)
 495         unlink(socket);
 496
 497     return 0;
 498 }