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 "nbd.h"
  20 #include "block.h"
  21
  22 #include "qemu-coroutine.h"
  23
  24 #include <errno.h>
  25 #include <string.h>
  26 #ifndef _WIN32
  27 #include <sys/ioctl.h>
  28 #endif
  29 #if defined(__sun__) || defined(__HAIKU__)
  30 #include <sys/ioccom.h>
  31 #endif
  32 #include <ctype.h>
  33 #include <inttypes.h>
  34
  35 #ifdef __linux__
  36 #include <linux/fs.h>
  37 #endif
  38
  39 #include "qemu_socket.h"
  40 #include "qemu-queue.h"
  41
  42 //#define DEBUG_NBD
  43
  44 #ifdef DEBUG_NBD
  45 #define TRACE(msg, ...) do { \
  46     LOG(msg, ## __VA_ARGS__); \
  47 } while(0)
  48 #else
  49 #define TRACE(msg, ...) \
  50     do { } while (0)
  51 #endif
  52
  53 #define LOG(msg, ...) do { \
  54     fprintf(stderr, "%s:%s():L%d: " msg "\n", \
  55             __FILE__, __FUNCTION__, __LINE__, ## __VA_ARGS__); \
  56 } while(0)
  57
  58 /* This is all part of the "official" NBD API */
  59
  60 #define NBD_REQUEST_SIZE        (4 + 4 + 8 + 8 + 4)
  61 #define NBD_REPLY_SIZE          (4 + 4 + 8)
  62 #define NBD_REQUEST_MAGIC       0x25609513
  63 #define NBD_REPLY_MAGIC         0x67446698
  64 #define NBD_OPTS_MAGIC          0x49484156454F5054LL
  65 #define NBD_CLIENT_MAGIC        0x0000420281861253LL
  66
  67 #define NBD_SET_SOCK            _IO(0xab, 0)
  68 #define NBD_SET_BLKSIZE         _IO(0xab, 1)
  69 #define NBD_SET_SIZE            _IO(0xab, 2)
  70 #define NBD_DO_IT               _IO(0xab, 3)
  71 #define NBD_CLEAR_SOCK          _IO(0xab, 4)
  72 #define NBD_CLEAR_QUE           _IO(0xab, 5)
  73 #define NBD_PRINT_DEBUG         _IO(0xab, 6)
  74 #define NBD_SET_SIZE_BLOCKS     _IO(0xab, 7)
  75 #define NBD_DISCONNECT          _IO(0xab, 8)
  76 #define NBD_SET_TIMEOUT         _IO(0xab, 9)
  77 #define NBD_SET_FLAGS           _IO(0xab, 10)
  78
  79 #define NBD_OPT_EXPORT_NAME     (1 << 0)
  80
  81 /* Definitions for opaque data types */
  82
  83 typedef struct NBDRequest NBDRequest;
  84
  85 struct NBDRequest {
  86     QSIMPLEQ_ENTRY(NBDRequest) entry;
  87     NBDClient *client;
  88     uint8_t *data;
  89 };
  90
  91 struct NBDExport {
  92     int refcount;
  93     void (*close)(NBDExport *exp);
  94
  95     BlockDriverState *bs;
  96     char *name;
  97     off_t dev_offset;
  98     off_t size;
  99     uint32_t nbdflags;
 100     QTAILQ_HEAD(, NBDClient) clients;
 101     QSIMPLEQ_HEAD(, NBDRequest) requests;
 102     QTAILQ_ENTRY(NBDExport) next;
 103 };
 104
 105 static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);
 106
 107 struct NBDClient {
 108     int refcount;
 109     void (*close)(NBDClient *client);
 110
 111     NBDExport *exp;
 112     int sock;
 113
 114     Coroutine *recv_coroutine;
 115
 116     CoMutex send_lock;
 117     Coroutine *send_coroutine;
 118
 119     QTAILQ_ENTRY(NBDClient) next;
 120     int nb_requests;
 121     bool closing;
 122 };
 123
 124 /* That's all folks */
 125
 126 ssize_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read)
 127 {
 128     size_t offset = 0;
 129     int err;
 130
 131     if (qemu_in_coroutine()) {
 132         if (do_read) {
 133             return qemu_co_recv(fd, buffer, size);
 134         } else {
 135             return qemu_co_send(fd, buffer, size);
 136         }
 137     }
 138
 139     while (offset < size) {
 140         ssize_t len;
 141
 142         if (do_read) {
 143             len = qemu_recv(fd, buffer + offset, size - offset, 0);
 144         } else {
 145             len = send(fd, buffer + offset, size - offset, 0);
 146         }
 147
 148         if (len < 0) {
 149             err = socket_error();
 150
 151             /* recoverable error */
 152             if (err == EINTR || (offset > 0 && err == EAGAIN)) {
 153                 continue;
 154             }
 155
 156             /* unrecoverable error */
 157             return -err;
 158         }
 159
 160         /* eof */
 161         if (len == 0) {
 162             break;
 163         }
 164
 165         offset += len;
 166     }
 167
 168     return offset;
 169 }
 170
 171 static ssize_t read_sync(int fd, void *buffer, size_t size)
 172 {
 173     /* Sockets are kept in blocking mode in the negotiation phase.  After
 174      * that, a non-readable socket simply means that another thread stole
 175      * our request/reply.  Synchronization is done with recv_coroutine, so
 176      * that this is coroutine-safe.
 177      */
 178     return nbd_wr_sync(fd, buffer, size, true);
 179 }
 180
 181 static ssize_t write_sync(int fd, void *buffer, size_t size)
 182 {
 183     int ret;
 184     do {
 185         /* For writes, we do expect the socket to be writable.  */
 186         ret = nbd_wr_sync(fd, buffer, size, false);
 187     } while (ret == -EAGAIN);
 188     return ret;
 189 }
 190
 191 static void combine_addr(char *buf, size_t len, const char* address,
 192                          uint16_t port)
 193 {
 194     /* If the address-part contains a colon, it's an IPv6 IP so needs [] */
 195     if (strstr(address, ":")) {
 196         snprintf(buf, len, "[%s]:%u", address, port);
 197     } else {
 198         snprintf(buf, len, "%s:%u", address, port);
 199     }
 200 }
 201
 202 int tcp_socket_outgoing(const char *address, uint16_t port)
 203 {
 204     char address_and_port[128];
 205     combine_addr(address_and_port, 128, address, port);
 206     return tcp_socket_outgoing_spec(address_and_port);
 207 }
 208
 209 int tcp_socket_outgoing_spec(const char *address_and_port)
 210 {
 211     Error *local_err = NULL;
 212     int fd = inet_connect(address_and_port, &local_err);
 213
 214     if (local_err != NULL) {
 215         qerror_report_err(local_err);
 216         error_free(local_err);
 217     }
 218     return fd;
 219 }
 220
 221 int tcp_socket_incoming(const char *address, uint16_t port)
 222 {
 223     char address_and_port[128];
 224     combine_addr(address_and_port, 128, address, port);
 225     return tcp_socket_incoming_spec(address_and_port);
 226 }
 227
 228 int tcp_socket_incoming_spec(const char *address_and_port)
 229 {
 230     Error *local_err = NULL;
 231     int fd = inet_listen(address_and_port, NULL, 0, SOCK_STREAM, 0, &local_err);
 232
 233     if (local_err != NULL) {
 234         qerror_report_err(local_err);
 235         error_free(local_err);
 236     }
 237     return fd;
 238 }
 239
 240 int unix_socket_incoming(const char *path)
 241 {
 242     Error *local_err = NULL;
 243     int fd = unix_listen(path, NULL, 0, &local_err);
 244
 245     if (local_err != NULL) {
 246         qerror_report_err(local_err);
 247         error_free(local_err);
 248     }
 249     return fd;
 250 }
 251
 252 int unix_socket_outgoing(const char *path)
 253 {
 254     Error *local_err = NULL;
 255     int fd = unix_connect(path, &local_err);
 256
 257     if (local_err != NULL) {
 258         qerror_report_err(local_err);
 259         error_free(local_err);
 260     }
 261     return fd;
 262 }
 263
 264 /* Basic flow for negotiation
 265
 266    Server         Client
 267    Negotiate
 268
 269    or
 270
 271    Server         Client
 272    Negotiate #1
 273                   Option
 274    Negotiate #2
 275
 276    ----
 277
 278    followed by
 279
 280    Server         Client
 281                   Request
 282    Response
 283                   Request
 284    Response
 285                   ...
 286    ...
 287                   Request (type == 2)
 288
 289 */
 290
 291 static int nbd_receive_options(NBDClient *client)
 292 {
 293     int csock = client->sock;
 294     char name[256];
 295     uint32_t tmp, length;
 296     uint64_t magic;
 297     int rc;
 298
 299     /* Client sends:
 300         [ 0 ..   3]   reserved (0)
 301         [ 4 ..  11]   NBD_OPTS_MAGIC
 302         [12 ..  15]   NBD_OPT_EXPORT_NAME
 303         [16 ..  19]   length
 304         [20 ..  xx]   export name (length bytes)
 305      */
 306
 307     rc = -EINVAL;
 308     if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 309         LOG("read failed");
 310         goto fail;
 311     }
 312     TRACE("Checking reserved");
 313     if (tmp != 0) {
 314         LOG("Bad reserved received");
 315         goto fail;
 316     }
 317
 318     if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
 319         LOG("read failed");
 320         goto fail;
 321     }
 322     TRACE("Checking reserved");
 323     if (magic != be64_to_cpu(NBD_OPTS_MAGIC)) {
 324         LOG("Bad magic received");
 325         goto fail;
 326     }
 327
 328     if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 329         LOG("read failed");
 330         goto fail;
 331     }
 332     TRACE("Checking option");
 333     if (tmp != be32_to_cpu(NBD_OPT_EXPORT_NAME)) {
 334         LOG("Bad option received");
 335         goto fail;
 336     }
 337
 338     if (read_sync(csock, &length, sizeof(length)) != sizeof(length)) {
 339         LOG("read failed");
 340         goto fail;
 341     }
 342     TRACE("Checking length");
 343     length = be32_to_cpu(length);
 344     if (length > 255) {
 345         LOG("Bad length received");
 346         goto fail;
 347     }
 348     if (read_sync(csock, name, length) != length) {
 349         LOG("read failed");
 350         goto fail;
 351     }
 352     name[length] = '\0';
 353
 354     client->exp = nbd_export_find(name);
 355     if (!client->exp) {
 356         LOG("export not found");
 357         goto fail;
 358     }
 359
 360     QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);
 361     nbd_export_get(client->exp);
 362
 363     TRACE("Option negotiation succeeded.");
 364     rc = 0;
 365 fail:
 366     return rc;
 367 }
 368
 369 static int nbd_send_negotiate(NBDClient *client)
 370 {
 371     int csock = client->sock;
 372     char buf[8 + 8 + 8 + 128];
 373     int rc;
 374     const int myflags = (NBD_FLAG_HAS_FLAGS | NBD_FLAG_SEND_TRIM |
 375                          NBD_FLAG_SEND_FLUSH | NBD_FLAG_SEND_FUA);
 376
 377     /* Negotiation header without options:
 378         [ 0 ..   7]   passwd       ("NBDMAGIC")
 379         [ 8 ..  15]   magic        (NBD_CLIENT_MAGIC)
 380         [16 ..  23]   size
 381         [24 ..  25]   server flags (0)
 382         [24 ..  27]   export flags
 383         [28 .. 151]   reserved     (0)
 384
 385        Negotiation header with options, part 1:
 386         [ 0 ..   7]   passwd       ("NBDMAGIC")
 387         [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)
 388         [16 ..  17]   server flags (0)
 389
 390        part 2 (after options are sent):
 391         [18 ..  25]   size
 392         [26 ..  27]   export flags
 393         [28 .. 151]   reserved     (0)
 394      */
 395
 396     socket_set_block(csock);
 397     rc = -EINVAL;
 398
 399     TRACE("Beginning negotiation.");
 400     memset(buf, 0, sizeof(buf));
 401     memcpy(buf, "NBDMAGIC", 8);
 402     if (client->exp) {
 403         assert ((client->exp->nbdflags & ~65535) == 0);
 404         cpu_to_be64w((uint64_t*)(buf + 8), NBD_CLIENT_MAGIC);
 405         cpu_to_be64w((uint64_t*)(buf + 16), client->exp->size);
 406         cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
 407     } else {
 408         cpu_to_be64w((uint64_t*)(buf + 8), NBD_OPTS_MAGIC);
 409     }
 410
 411     if (client->exp) {
 412         if (write_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
 413             LOG("write failed");
 414             goto fail;
 415         }
 416     } else {
 417         if (write_sync(csock, buf, 18) != 18) {
 418             LOG("write failed");
 419             goto fail;
 420         }
 421         rc = nbd_receive_options(client);
 422         if (rc < 0) {
 423             LOG("option negotiation failed");
 424             goto fail;
 425         }
 426
 427         assert ((client->exp->nbdflags & ~65535) == 0);
 428         cpu_to_be64w((uint64_t*)(buf + 18), client->exp->size);
 429         cpu_to_be16w((uint16_t*)(buf + 26), client->exp->nbdflags | myflags);
 430         if (write_sync(csock, buf + 18, sizeof(buf) - 18) != sizeof(buf) - 18) {
 431             LOG("write failed");
 432             goto fail;
 433         }
 434     }
 435
 436     TRACE("Negotiation succeeded.");
 437     rc = 0;
 438 fail:
 439     socket_set_nonblock(csock);
 440     return rc;
 441 }
 442
 443 int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
 444                           off_t *size, size_t *blocksize)
 445 {
 446     char buf[256];
 447     uint64_t magic, s;
 448     uint16_t tmp;
 449     int rc;
 450
 451     TRACE("Receiving negotiation.");
 452
 453     socket_set_block(csock);
 454     rc = -EINVAL;
 455
 456     if (read_sync(csock, buf, 8) != 8) {
 457         LOG("read failed");
 458         goto fail;
 459     }
 460
 461     buf[8] = '\0';
 462     if (strlen(buf) == 0) {
 463         LOG("server connection closed");
 464         goto fail;
 465     }
 466
 467     TRACE("Magic is %c%c%c%c%c%c%c%c",
 468           qemu_isprint(buf[0]) ? buf[0] : '.',
 469           qemu_isprint(buf[1]) ? buf[1] : '.',
 470           qemu_isprint(buf[2]) ? buf[2] : '.',
 471           qemu_isprint(buf[3]) ? buf[3] : '.',
 472           qemu_isprint(buf[4]) ? buf[4] : '.',
 473           qemu_isprint(buf[5]) ? buf[5] : '.',
 474           qemu_isprint(buf[6]) ? buf[6] : '.',
 475           qemu_isprint(buf[7]) ? buf[7] : '.');
 476
 477     if (memcmp(buf, "NBDMAGIC", 8) != 0) {
 478         LOG("Invalid magic received");
 479         goto fail;
 480     }
 481
 482     if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
 483         LOG("read failed");
 484         goto fail;
 485     }
 486     magic = be64_to_cpu(magic);
 487     TRACE("Magic is 0x%" PRIx64, magic);
 488
 489     if (name) {
 490         uint32_t reserved = 0;
 491         uint32_t opt;
 492         uint32_t namesize;
 493
 494         TRACE("Checking magic (opts_magic)");
 495         if (magic != NBD_OPTS_MAGIC) {
 496             LOG("Bad magic received");
 497             goto fail;
 498         }
 499         if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 500             LOG("flags read failed");
 501             goto fail;
 502         }
 503         *flags = be16_to_cpu(tmp) << 16;
 504         /* reserved for future use */
 505         if (write_sync(csock, &reserved, sizeof(reserved)) !=
 506             sizeof(reserved)) {
 507             LOG("write failed (reserved)");
 508             goto fail;
 509         }
 510         /* write the export name */
 511         magic = cpu_to_be64(magic);
 512         if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
 513             LOG("write failed (magic)");
 514             goto fail;
 515         }
 516         opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
 517         if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
 518             LOG("write failed (opt)");
 519             goto fail;
 520         }
 521         namesize = cpu_to_be32(strlen(name));
 522         if (write_sync(csock, &namesize, sizeof(namesize)) !=
 523             sizeof(namesize)) {
 524             LOG("write failed (namesize)");
 525             goto fail;
 526         }
 527         if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
 528             LOG("write failed (name)");
 529             goto fail;
 530         }
 531     } else {
 532         TRACE("Checking magic (cli_magic)");
 533
 534         if (magic != NBD_CLIENT_MAGIC) {
 535             LOG("Bad magic received");
 536             goto fail;
 537         }
 538     }
 539
 540     if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
 541         LOG("read failed");
 542         goto fail;
 543     }
 544     *size = be64_to_cpu(s);
 545     *blocksize = 1024;
 546     TRACE("Size is %" PRIu64, *size);
 547
 548     if (!name) {
 549         if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
 550             LOG("read failed (flags)");
 551             goto fail;
 552         }
 553         *flags = be32_to_cpup(flags);
 554     } else {
 555         if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
 556             LOG("read failed (tmp)");
 557             goto fail;
 558         }
 559         *flags |= be32_to_cpu(tmp);
 560     }
 561     if (read_sync(csock, &buf, 124) != 124) {
 562         LOG("read failed (buf)");
 563         goto fail;
 564     }
 565     rc = 0;
 566
 567 fail:
 568     socket_set_nonblock(csock);
 569     return rc;
 570 }
 571
 572 #ifdef __linux__
 573 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
 574 {
 575     TRACE("Setting NBD socket");
 576
 577     if (ioctl(fd, NBD_SET_SOCK, csock) < 0) {
 578         int serrno = errno;
 579         LOG("Failed to set NBD socket");
 580         return -serrno;
 581     }
 582
 583     TRACE("Setting block size to %lu", (unsigned long)blocksize);
 584
 585     if (ioctl(fd, NBD_SET_BLKSIZE, blocksize) < 0) {
 586         int serrno = errno;
 587         LOG("Failed setting NBD block size");
 588         return -serrno;
 589     }
 590
 591         TRACE("Setting size to %zd block(s)", (size_t)(size / blocksize));
 592
 593     if (ioctl(fd, NBD_SET_SIZE_BLOCKS, size / blocksize) < 0) {
 594         int serrno = errno;
 595         LOG("Failed setting size (in blocks)");
 596         return -serrno;
 597     }
 598
 599     if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) {
 600         if (errno == ENOTTY) {
 601             int read_only = (flags & NBD_FLAG_READ_ONLY) != 0;
 602             TRACE("Setting readonly attribute");
 603
 604             if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
 605                 int serrno = errno;
 606                 LOG("Failed setting read-only attribute");
 607                 return -serrno;
 608             }
 609         } else {
 610             int serrno = errno;
 611             LOG("Failed setting flags");
 612             return -serrno;
 613         }
 614     }
 615
 616     TRACE("Negotiation ended");
 617
 618     return 0;
 619 }
 620
 621 int nbd_disconnect(int fd)
 622 {
 623     ioctl(fd, NBD_CLEAR_QUE);
 624     ioctl(fd, NBD_DISCONNECT);
 625     ioctl(fd, NBD_CLEAR_SOCK);
 626     return 0;
 627 }
 628
 629 int nbd_client(int fd)
 630 {
 631     int ret;
 632     int serrno;
 633
 634     TRACE("Doing NBD loop");
 635
 636     ret = ioctl(fd, NBD_DO_IT);
 637     if (ret < 0 && errno == EPIPE) {
 638         /* NBD_DO_IT normally returns EPIPE when someone has disconnected
 639          * the socket via NBD_DISCONNECT.  We do not want to return 1 in
 640          * that case.
 641          */
 642         ret = 0;
 643     }
 644     serrno = errno;
 645
 646     TRACE("NBD loop returned %d: %s", ret, strerror(serrno));
 647
 648     TRACE("Clearing NBD queue");
 649     ioctl(fd, NBD_CLEAR_QUE);
 650
 651     TRACE("Clearing NBD socket");
 652     ioctl(fd, NBD_CLEAR_SOCK);
 653
 654     errno = serrno;
 655     return ret;
 656 }
 657 #else
 658 int nbd_init(int fd, int csock, uint32_t flags, off_t size, size_t blocksize)
 659 {
 660     return -ENOTSUP;
 661 }
 662
 663 int nbd_disconnect(int fd)
 664 {
 665     return -ENOTSUP;
 666 }
 667
 668 int nbd_client(int fd)
 669 {
 670     return -ENOTSUP;
 671 }
 672 #endif
 673
 674 ssize_t nbd_send_request(int csock, struct nbd_request *request)
 675 {
 676     uint8_t buf[NBD_REQUEST_SIZE];
 677     ssize_t ret;
 678
 679     cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC);
 680     cpu_to_be32w((uint32_t*)(buf + 4), request->type);
 681     cpu_to_be64w((uint64_t*)(buf + 8), request->handle);
 682     cpu_to_be64w((uint64_t*)(buf + 16), request->from);
 683     cpu_to_be32w((uint32_t*)(buf + 24), request->len);
 684
 685     TRACE("Sending request to client: "
 686           "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
 687           request->from, request->len, request->handle, request->type);
 688
 689     ret = write_sync(csock, buf, sizeof(buf));
 690     if (ret < 0) {
 691         return ret;
 692     }
 693
 694     if (ret != sizeof(buf)) {
 695         LOG("writing to socket failed");
 696         return -EINVAL;
 697     }
 698     return 0;
 699 }
 700
 701 static ssize_t nbd_receive_request(int csock, struct nbd_request *request)
 702 {
 703     uint8_t buf[NBD_REQUEST_SIZE];
 704     uint32_t magic;
 705     ssize_t ret;
 706
 707     ret = read_sync(csock, buf, sizeof(buf));
 708     if (ret < 0) {
 709         return ret;
 710     }
 711
 712     if (ret != sizeof(buf)) {
 713         LOG("read failed");
 714         return -EINVAL;
 715     }
 716
 717     /* Request
 718        [ 0 ..  3]   magic   (NBD_REQUEST_MAGIC)
 719        [ 4 ..  7]   type    (0 == READ, 1 == WRITE)
 720        [ 8 .. 15]   handle
 721        [16 .. 23]   from
 722        [24 .. 27]   len
 723      */
 724
 725     magic = be32_to_cpup((uint32_t*)buf);
 726     request->type  = be32_to_cpup((uint32_t*)(buf + 4));
 727     request->handle = be64_to_cpup((uint64_t*)(buf + 8));
 728     request->from  = be64_to_cpup((uint64_t*)(buf + 16));
 729     request->len   = be32_to_cpup((uint32_t*)(buf + 24));
 730
 731     TRACE("Got request: "
 732           "{ magic = 0x%x, .type = %d, from = %" PRIu64" , len = %u }",
 733           magic, request->type, request->from, request->len);
 734
 735     if (magic != NBD_REQUEST_MAGIC) {
 736         LOG("invalid magic (got 0x%x)", magic);
 737         return -EINVAL;
 738     }
 739     return 0;
 740 }
 741
 742 ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply)
 743 {
 744     uint8_t buf[NBD_REPLY_SIZE];
 745     uint32_t magic;
 746     ssize_t ret;
 747
 748     ret = read_sync(csock, buf, sizeof(buf));
 749     if (ret < 0) {
 750         return ret;
 751     }
 752
 753     if (ret != sizeof(buf)) {
 754         LOG("read failed");
 755         return -EINVAL;
 756     }
 757
 758     /* Reply
 759        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 760        [ 4 ..  7]    error   (0 == no error)
 761        [ 7 .. 15]    handle
 762      */
 763
 764     magic = be32_to_cpup((uint32_t*)buf);
 765     reply->error  = be32_to_cpup((uint32_t*)(buf + 4));
 766     reply->handle = be64_to_cpup((uint64_t*)(buf + 8));
 767
 768     TRACE("Got reply: "
 769           "{ magic = 0x%x, .error = %d, handle = %" PRIu64" }",
 770           magic, reply->error, reply->handle);
 771
 772     if (magic != NBD_REPLY_MAGIC) {
 773         LOG("invalid magic (got 0x%x)", magic);
 774         return -EINVAL;
 775     }
 776     return 0;
 777 }
 778
 779 static ssize_t nbd_send_reply(int csock, struct nbd_reply *reply)
 780 {
 781     uint8_t buf[NBD_REPLY_SIZE];
 782     ssize_t ret;
 783
 784     /* Reply
 785        [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
 786        [ 4 ..  7]    error   (0 == no error)
 787        [ 7 .. 15]    handle
 788      */
 789     cpu_to_be32w((uint32_t*)buf, NBD_REPLY_MAGIC);
 790     cpu_to_be32w((uint32_t*)(buf + 4), reply->error);
 791     cpu_to_be64w((uint64_t*)(buf + 8), reply->handle);
 792
 793     TRACE("Sending response to client");
 794
 795     ret = write_sync(csock, buf, sizeof(buf));
 796     if (ret < 0) {
 797         return ret;
 798     }
 799
 800     if (ret != sizeof(buf)) {
 801         LOG("writing to socket failed");
 802         return -EINVAL;
 803     }
 804     return 0;
 805 }
 806
 807 #define MAX_NBD_REQUESTS 16
 808
 809 void nbd_client_get(NBDClient *client)
 810 {
 811     client->refcount++;
 812 }
 813
 814 void nbd_client_put(NBDClient *client)
 815 {
 816     if (--client->refcount == 0) {
 817         /* The last reference should be dropped by client->close,
 818          * which is called by nbd_client_close.
 819          */
 820         assert(client->closing);
 821
 822         qemu_set_fd_handler2(client->sock, NULL, NULL, NULL, NULL);
 823         close(client->sock);
 824         client->sock = -1;
 825         if (client->exp) {
 826             QTAILQ_REMOVE(&client->exp->clients, client, next);
 827             nbd_export_put(client->exp);
 828         }
 829         g_free(client);
 830     }
 831 }
 832
 833 void nbd_client_close(NBDClient *client)
 834 {
 835     if (client->closing) {
 836         return;
 837     }
 838
 839     client->closing = true;
 840
 841     /* Force requests to finish.  They will drop their own references,
 842      * then we'll close the socket and free the NBDClient.
 843      */
 844     shutdown(client->sock, 2);
 845
 846     /* Also tell the client, so that they release their reference.  */
 847     if (client->close) {
 848         client->close(client);
 849     }
 850 }
 851
 852 static NBDRequest *nbd_request_get(NBDClient *client)
 853 {
 854     NBDRequest *req;
 855     NBDExport *exp = client->exp;
 856
 857     assert(client->nb_requests <= MAX_NBD_REQUESTS - 1);
 858     client->nb_requests++;
 859
 860     if (QSIMPLEQ_EMPTY(&exp->requests)) {
 861         req = g_malloc0(sizeof(NBDRequest));
 862         req->data = qemu_blockalign(exp->bs, NBD_BUFFER_SIZE);
 863     } else {
 864         req = QSIMPLEQ_FIRST(&exp->requests);
 865         QSIMPLEQ_REMOVE_HEAD(&exp->requests, entry);
 866     }
 867     nbd_client_get(client);
 868     req->client = client;
 869     return req;
 870 }
 871
 872 static void nbd_request_put(NBDRequest *req)
 873 {
 874     NBDClient *client = req->client;
 875     QSIMPLEQ_INSERT_HEAD(&client->exp->requests, req, entry);
 876     if (client->nb_requests-- == MAX_NBD_REQUESTS) {
 877         qemu_notify_event();
 878     }
 879     nbd_client_put(client);
 880 }
 881
 882 NBDExport *nbd_export_new(BlockDriverState *bs, off_t dev_offset,
 883                           off_t size, uint32_t nbdflags,
 884                           void (*close)(NBDExport *))
 885 {
 886     NBDExport *exp = g_malloc0(sizeof(NBDExport));
 887     QSIMPLEQ_INIT(&exp->requests);
 888     exp->refcount = 1;
 889     QTAILQ_INIT(&exp->clients);
 890     exp->bs = bs;
 891     exp->dev_offset = dev_offset;
 892     exp->nbdflags = nbdflags;
 893     exp->size = size == -1 ? bdrv_getlength(bs) : size;
 894     exp->close = close;
 895     return exp;
 896 }
 897
 898 NBDExport *nbd_export_find(const char *name)
 899 {
 900     NBDExport *exp;
 901     QTAILQ_FOREACH(exp, &exports, next) {
 902         if (strcmp(name, exp->name) == 0) {
 903             return exp;
 904         }
 905     }
 906
 907     return NULL;
 908 }
 909
 910 void nbd_export_set_name(NBDExport *exp, const char *name)
 911 {
 912     if (exp->name == name) {
 913         return;
 914     }
 915
 916     nbd_export_get(exp);
 917     if (exp->name != NULL) {
 918         g_free(exp->name);
 919         exp->name = NULL;
 920         QTAILQ_REMOVE(&exports, exp, next);
 921         nbd_export_put(exp);
 922     }
 923     if (name != NULL) {
 924         nbd_export_get(exp);
 925         exp->name = g_strdup(name);
 926         QTAILQ_INSERT_TAIL(&exports, exp, next);
 927     }
 928     nbd_export_put(exp);
 929 }
 930
 931 void nbd_export_close(NBDExport *exp)
 932 {
 933     NBDClient *client, *next;
 934
 935     nbd_export_get(exp);
 936     QTAILQ_FOREACH_SAFE(client, &exp->clients, next, next) {
 937         nbd_client_close(client);
 938     }
 939     nbd_export_set_name(exp, NULL);
 940     nbd_export_put(exp);
 941 }
 942
 943 void nbd_export_get(NBDExport *exp)
 944 {
 945     assert(exp->refcount > 0);
 946     exp->refcount++;
 947 }
 948
 949 void nbd_export_put(NBDExport *exp)
 950 {
 951     assert(exp->refcount > 0);
 952     if (exp->refcount == 1) {
 953         nbd_export_close(exp);
 954     }
 955
 956     if (--exp->refcount == 0) {
 957         assert(exp->name == NULL);
 958
 959         if (exp->close) {
 960             exp->close(exp);
 961         }
 962
 963         while (!QSIMPLEQ_EMPTY(&exp->requests)) {
 964             NBDRequest *first = QSIMPLEQ_FIRST(&exp->requests);
 965             QSIMPLEQ_REMOVE_HEAD(&exp->requests, entry);
 966             qemu_vfree(first->data);
 967             g_free(first);
 968         }
 969
 970         g_free(exp);
 971     }
 972 }
 973
 974 BlockDriverState *nbd_export_get_blockdev(NBDExport *exp)
 975 {
 976     return exp->bs;
 977 }
 978
 979 void nbd_export_close_all(void)
 980 {
 981     NBDExport *exp, *next;
 982
 983     QTAILQ_FOREACH_SAFE(exp, &exports, next, next) {
 984         nbd_export_close(exp);
 985     }
 986 }
 987
 988 static int nbd_can_read(void *opaque);
 989 static void nbd_read(void *opaque);
 990 static void nbd_restart_write(void *opaque);
 991
 992 static ssize_t nbd_co_send_reply(NBDRequest *req, struct nbd_reply *reply,
 993                                  int len)
 994 {
 995     NBDClient *client = req->client;
 996     int csock = client->sock;
 997     ssize_t rc, ret;
 998
 999     qemu_co_mutex_lock(&client->send_lock);
1000     qemu_set_fd_handler2(csock, nbd_can_read, nbd_read,
1001                          nbd_restart_write, client);
1002     client->send_coroutine = qemu_coroutine_self();
1003
1004     if (!len) {
1005         rc = nbd_send_reply(csock, reply);
1006     } else {
1007         socket_set_cork(csock, 1);
1008         rc = nbd_send_reply(csock, reply);
1009         if (rc >= 0) {
1010             ret = qemu_co_send(csock, req->data, len);
1011             if (ret != len) {
1012                 rc = -EIO;
1013             }
1014         }
1015         socket_set_cork(csock, 0);
1016     }
1017
1018     client->send_coroutine = NULL;
1019     qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client);
1020     qemu_co_mutex_unlock(&client->send_lock);
1021     return rc;
1022 }
1023
1024 static ssize_t nbd_co_receive_request(NBDRequest *req, struct nbd_request *request)
1025 {
1026     NBDClient *client = req->client;
1027     int csock = client->sock;
1028     ssize_t rc;
1029
1030     client->recv_coroutine = qemu_coroutine_self();
1031     rc = nbd_receive_request(csock, request);
1032     if (rc < 0) {
1033         if (rc != -EAGAIN) {
1034             rc = -EIO;
1035         }
1036         goto out;
1037     }
1038
1039     if (request->len > NBD_BUFFER_SIZE) {
1040         LOG("len (%u) is larger than max len (%u)",
1041             request->len, NBD_BUFFER_SIZE);
1042         rc = -EINVAL;
1043         goto out;
1044     }
1045
1046     if ((request->from + request->len) < request->from) {
1047         LOG("integer overflow detected! "
1048             "you're probably being attacked");
1049         rc = -EINVAL;
1050         goto out;
1051     }
1052
1053     TRACE("Decoding type");
1054
1055     if ((request->type & NBD_CMD_MASK_COMMAND) == NBD_CMD_WRITE) {
1056         TRACE("Reading %u byte(s)", request->len);
1057
1058         if (qemu_co_recv(csock, req->data, request->len) != request->len) {
1059             LOG("reading from socket failed");
1060             rc = -EIO;
1061             goto out;
1062         }
1063     }
1064     rc = 0;
1065
1066 out:
1067     client->recv_coroutine = NULL;
1068     return rc;
1069 }
1070
1071 static void nbd_trip(void *opaque)
1072 {
1073     NBDClient *client = opaque;
1074     NBDExport *exp = client->exp;
1075     NBDRequest *req;
1076     struct nbd_request request;
1077     struct nbd_reply reply;
1078     ssize_t ret;
1079
1080     TRACE("Reading request.");
1081     if (client->closing) {
1082         return;
1083     }
1084
1085     req = nbd_request_get(client);
1086     ret = nbd_co_receive_request(req, &request);
1087     if (ret == -EAGAIN) {
1088         goto done;
1089     }
1090     if (ret == -EIO) {
1091         goto out;
1092     }
1093
1094     reply.handle = request.handle;
1095     reply.error = 0;
1096
1097     if (ret < 0) {
1098         reply.error = -ret;
1099         goto error_reply;
1100     }
1101
1102     if ((request.from + request.len) > exp->size) {
1103             LOG("From: %" PRIu64 ", Len: %u, Size: %" PRIu64
1104             ", Offset: %" PRIu64 "\n",
1105                     request.from, request.len,
1106                     (uint64_t)exp->size, (uint64_t)exp->dev_offset);
1107         LOG("requested operation past EOF--bad client?");
1108         goto invalid_request;
1109     }
1110
1111     switch (request.type & NBD_CMD_MASK_COMMAND) {
1112     case NBD_CMD_READ:
1113         TRACE("Request type is READ");
1114
1115         if (request.type & NBD_CMD_FLAG_FUA) {
1116             ret = bdrv_co_flush(exp->bs);
1117             if (ret < 0) {
1118                 LOG("flush failed");
1119                 reply.error = -ret;
1120                 goto error_reply;
1121             }
1122         }
1123
1124         ret = bdrv_read(exp->bs, (request.from + exp->dev_offset) / 512,
1125                         req->data, request.len / 512);
1126         if (ret < 0) {
1127             LOG("reading from file failed");
1128             reply.error = -ret;
1129             goto error_reply;
1130         }
1131
1132         TRACE("Read %u byte(s)", request.len);
1133         if (nbd_co_send_reply(req, &reply, request.len) < 0)
1134             goto out;
1135         break;
1136     case NBD_CMD_WRITE:
1137         TRACE("Request type is WRITE");
1138
1139         if (exp->nbdflags & NBD_FLAG_READ_ONLY) {
1140             TRACE("Server is read-only, return error");
1141             reply.error = EROFS;
1142             goto error_reply;
1143         }
1144
1145         TRACE("Writing to device");
1146
1147         ret = bdrv_write(exp->bs, (request.from + exp->dev_offset) / 512,
1148                          req->data, request.len / 512);
1149         if (ret < 0) {
1150             LOG("writing to file failed");
1151             reply.error = -ret;
1152             goto error_reply;
1153         }
1154
1155         if (request.type & NBD_CMD_FLAG_FUA) {
1156             ret = bdrv_co_flush(exp->bs);
1157             if (ret < 0) {
1158                 LOG("flush failed");
1159                 reply.error = -ret;
1160                 goto error_reply;
1161             }
1162         }
1163
1164         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1165             goto out;
1166         }
1167         break;
1168     case NBD_CMD_DISC:
1169         TRACE("Request type is DISCONNECT");
1170         errno = 0;
1171         goto out;
1172     case NBD_CMD_FLUSH:
1173         TRACE("Request type is FLUSH");
1174
1175         ret = bdrv_co_flush(exp->bs);
1176         if (ret < 0) {
1177             LOG("flush failed");
1178             reply.error = -ret;
1179         }
1180         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1181             goto out;
1182         }
1183         break;
1184     case NBD_CMD_TRIM:
1185         TRACE("Request type is TRIM");
1186         ret = bdrv_co_discard(exp->bs, (request.from + exp->dev_offset) / 512,
1187                               request.len / 512);
1188         if (ret < 0) {
1189             LOG("discard failed");
1190             reply.error = -ret;
1191         }
1192         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1193             goto out;
1194         }
1195         break;
1196     default:
1197         LOG("invalid request type (%u) received", request.type);
1198     invalid_request:
1199         reply.error = -EINVAL;
1200     error_reply:
1201         if (nbd_co_send_reply(req, &reply, 0) < 0) {
1202             goto out;
1203         }
1204         break;
1205     }
1206
1207     TRACE("Request/Reply complete");
1208
1209 done:
1210     nbd_request_put(req);
1211     return;
1212
1213 out:
1214     nbd_request_put(req);
1215     nbd_client_close(client);
1216 }
1217
1218 static int nbd_can_read(void *opaque)
1219 {
1220     NBDClient *client = opaque;
1221
1222     return client->recv_coroutine || client->nb_requests < MAX_NBD_REQUESTS;
1223 }
1224
1225 static void nbd_read(void *opaque)
1226 {
1227     NBDClient *client = opaque;
1228
1229     if (client->recv_coroutine) {
1230         qemu_coroutine_enter(client->recv_coroutine, NULL);
1231     } else {
1232         qemu_coroutine_enter(qemu_coroutine_create(nbd_trip), client);
1233     }
1234 }
1235
1236 static void nbd_restart_write(void *opaque)
1237 {
1238     NBDClient *client = opaque;
1239
1240     qemu_coroutine_enter(client->send_coroutine, NULL);
1241 }
1242
1243 NBDClient *nbd_client_new(NBDExport *exp, int csock,
1244                           void (*close)(NBDClient *))
1245 {
1246     NBDClient *client;
1247     client = g_malloc0(sizeof(NBDClient));
1248     client->refcount = 1;
1249     client->exp = exp;
1250     client->sock = csock;
1251     if (nbd_send_negotiate(client) < 0) {
1252         g_free(client);
1253         return NULL;
1254     }
1255     client->close = close;
1256     qemu_co_mutex_init(&client->send_lock);
1257     qemu_set_fd_handler2(csock, nbd_can_read, nbd_read, NULL, client);
1258
1259     if (exp) {
1260         QTAILQ_INSERT_TAIL(&exp->clients, client, next);
1261         nbd_export_get(exp);
1262     }
1263     return client;
1264 }