nbd-client.c

   1 /*
   2  * Open connection for network block device
   3  *
   4  * Copyright 1997,1998 Pavel Machek, distribute under GPL
   5  *  <pavel@atrey.karlin.mff.cuni.cz>
   6  * Copyright (c) 2002 - 2011 Wouter Verhelst <w@uter.be>
   7  *
   8  * Version 1.0 - 64bit issues should be fixed, now
   9  * Version 1.1 - added bs (blocksize) option (Alexey Guzeev, aga@permonline.ru)
  10  * Version 1.2 - I added new option '-d' to send the disconnect request
  11  * Version 2.0 - Version synchronised with server
  12  * Version 2.1 - Check for disconnection before INIT_PASSWD is received
  13  *      to make errormsg a bit more helpful in case the server can't
  14  *      open the exported file.
  15  * 16/03/2010 - Add IPv6 support.
  16  *      Kitt Tientanopajai <kitt@kitty.in.th>
  17  *      Neutron Soutmun <neo.neutron@gmail.com>
  18  *      Suriya Soutmun <darksolar@gmail.com>
  19  */
  20
  21 #include "config.h"
  22 #include "lfs.h"
  23
  24 #include <sys/ioctl.h>
  25 #include <sys/socket.h>
  26 #include <sys/types.h>
  27 #include <unistd.h>
  28 #include <netinet/tcp.h>
  29 #include <netinet/in.h>
  30 #include <netdb.h>
  31 #include "netdb-compat.h"
  32 #include <stdio.h>
  33 #include <fcntl.h>
  34 #include <syslog.h>
  35 #include <stdlib.h>
  36 #include <sys/mount.h>
  37 #include <sys/mman.h>
  38 #include <signal.h>
  39 #include <errno.h>
  40 #include <getopt.h>
  41 #include <stdarg.h>
  42
  43 #include <linux/ioctl.h>
  44 #define MY_NAME "nbd_client"
  45 #include "cliserv.h"
  46
  47 #ifdef WITH_SDP
  48 #include <sdp_inet.h>
  49 #endif
  50
  51 #define NBDC_DO_LIST 1
  52
  53 int check_conn(char* devname, int do_print) {
  54         char buf[256];
  55         char* p;
  56         int fd;
  57         int len;
  58
  59         if( (p=strrchr(devname, '/')) ) {
  60                 devname=p+1;
  61         }
  62         if((p=strchr(devname, 'p'))) {
  63                 /* We can't do checks on partitions. */
  64                 *p='\0';
  65         }
  66         snprintf(buf, 256, "/sys/block/%s/pid", devname);
  67         if((fd=open(buf, O_RDONLY))<0) {
  68                 if(errno==ENOENT) {
  69                         return 1;
  70                 } else {
  71                         return 2;
  72                 }
  73         }
  74         len=read(fd, buf, 256);
  75         if(len >= 0)
  76                 buf[len]='\0';
  77         if(do_print) printf("%s\n", buf);
  78         return 0;
  79 }
  80
  81 int opennet(char *name, char* portstr, int sdp) {
  82         int sock;
  83         struct addrinfo hints;
  84         struct addrinfo *ai = NULL;
  85         struct addrinfo *rp = NULL;
  86         int e;
  87
  88         memset(&hints,'\0',sizeof(hints));
  89         hints.ai_family = AF_UNSPEC;
  90         hints.ai_socktype = SOCK_STREAM;
  91         hints.ai_flags = AI_ADDRCONFIG | AI_NUMERICSERV;
  92         hints.ai_protocol = IPPROTO_TCP;
  93
  94         e = getaddrinfo(name, portstr, &hints, &ai);
  95
  96         if(e != 0) {
  97                 fprintf(stderr, "getaddrinfo failed: %s\n", gai_strerror(e));
  98                 freeaddrinfo(ai);
  99                 return -1;
 100         }
 101
 102         if(sdp) {
 103 #ifdef WITH_SDP
 104                 if (ai->ai_family == AF_INET)
 105                         ai->ai_family = AF_INET_SDP;
 106                 else (ai->ai_family == AF_INET6)
 107                         ai->ai_family = AF_INET6_SDP;
 108 #else
 109                 err("Can't do SDP: I was not compiled with SDP support!");
 110 #endif
 111         }
 112
 113         for(rp = ai; rp != NULL; rp = rp->ai_next) {
 114                 sock = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
 115
 116                 if(sock == -1)
 117                         continue;       /* error */
 118
 119                 if(connect(sock, rp->ai_addr, rp->ai_addrlen) != -1)
 120                         break;          /* success */
 121
 122                 close(sock);
 123         }
 124
 125         if (rp == NULL) {
 126                 err_nonfatal("Socket failed: %m");
 127                 return -1;
 128         }
 129
 130         setmysockopt(sock);
 131
 132         freeaddrinfo(ai);
 133         return sock;
 134 }
 135
 136 void ask_list(int sock) {
 137         uint32_t opt;
 138         uint32_t opt_server;
 139         uint32_t len;
 140         uint32_t reptype;
 141         uint64_t magic;
 142         const int BUF_SIZE = 1024;
 143         char buf[BUF_SIZE];
 144
 145         magic = ntohll(opts_magic);
 146         if (write(sock, &magic, sizeof(magic)) < 0)
 147                 err("Failed/2.2: %m");
 148
 149         /* Ask for the list */
 150         opt = htonl(NBD_OPT_LIST);
 151         if(write(sock, &opt, sizeof(opt)) < 0) {
 152                 err("writing list option failed: %m");
 153         }
 154         /* Send the length (zero) */
 155         len = htonl(0);
 156         if(write(sock, &len, sizeof(len)) < 0) {
 157                 err("writing length failed: %m");
 158         }
 159         /* newline, move away from the "Negotiation:" line */
 160         printf("\n");
 161         do {
 162                 memset(buf, 0, 1024);
 163                 if(read(sock, &magic, sizeof(magic)) < 0) {
 164                         err("Reading magic from server: %m");
 165                 }
 166                 if(read(sock, &opt_server, sizeof(opt_server)) < 0) {
 167                         err("Reading option: %m");
 168                 }
 169                 if(read(sock, &reptype, sizeof(reptype)) <0) {
 170                         err("Reading reply from server: %m");
 171                 }
 172                 if(read(sock, &len, sizeof(len)) < 0) {
 173                         err("Reading length from server: %m");
 174                 }
 175                 magic=ntohll(magic);
 176                 len=ntohl(len);
 177                 reptype=ntohl(reptype);
 178                 if(magic != rep_magic) {
 179                         err("Not enough magic from server");
 180                 }
 181                 if(reptype & NBD_REP_FLAG_ERROR) {
 182                         switch(reptype) {
 183                                 case NBD_REP_ERR_POLICY:
 184                                         fprintf(stderr, "\nE: listing not allowed by server.\n");
 185                                         break;
 186                                 default:
 187                                         fprintf(stderr, "\nE: unexpected error from server.\n");
 188                                         break;
 189                         }
 190                         if(len > 0 && len < BUF_SIZE) {
 191                                 if(len=read(sock, buf, len) < 0) {
 192                                         fprintf(stderr, "\nE: could not read error message from server\n");
 193                                 }
 194                                 buf[len] = '\0';
 195                                 fprintf(stderr, "Server said: %s\n", buf);
 196                         }
 197                         exit(EXIT_FAILURE);
 198                 } else {
 199                         if(len) {
 200                                 if(reptype != NBD_REP_SERVER) {
 201                                         err("Server sent us a reply we don't understand!");
 202                                 }
 203                                 if(read(sock, &len, sizeof(len)) < 0) {
 204                                         fprintf(stderr, "\nE: could not read export name length from server\n");
 205                                         exit(EXIT_FAILURE);
 206                                 }
 207                                 len=ntohl(len);
 208                                 if (len >= BUF_SIZE) {
 209                                         fprintf(stderr, "\nE: export name on server too long\n");
 210                                         exit(EXIT_FAILURE);
 211                                 }
 212                                 if(read(sock, buf, len) < 0) {
 213                                         fprintf(stderr, "\nE: could not read export name from server\n");
 214                                         exit(EXIT_FAILURE);
 215                                 }
 216                                 buf[len] = 0;
 217                                 printf("%s\n", buf);
 218                         }
 219                 }
 220         } while(reptype != NBD_REP_ACK);
 221         opt=htonl(NBD_OPT_ABORT);
 222         len=htonl(0);
 223         magic=htonll(opts_magic);
 224         if (write(sock, &magic, sizeof(magic)) < 0)
 225                 err("Failed/2.2: %m");
 226         if (write(sock, &opt, sizeof(opt)) < 0)
 227                 err("Failed writing abort");
 228         if (write(sock, &len, sizeof(len)) < 0)
 229                 err("Failed writing length");
 230 }
 231
 232 void negotiate(int sock, u64 *rsize64, u32 *flags, char* name, uint32_t needed_flags, uint32_t client_flags, uint32_t do_opts) {
 233         u64 magic, size64;
 234         uint16_t tmp;
 235         char buf[256] = "\0\0\0\0\0\0\0\0\0";
 236
 237         printf("Negotiation: ");
 238         if (read(sock, buf, 8) < 0)
 239                 err("Failed/1: %m");
 240         if (strlen(buf)==0)
 241                 err("Server closed connection");
 242         if (strcmp(buf, INIT_PASSWD))
 243                 err("INIT_PASSWD bad");
 244         printf(".");
 245         if (read(sock, &magic, sizeof(magic)) < 0)
 246                 err("Failed/2: %m");
 247         magic = ntohll(magic);
 248         if(name) {
 249                 uint32_t opt;
 250                 uint32_t namesize;
 251
 252                 if (magic != opts_magic) {
 253                         if(magic == cliserv_magic) {
 254                                 err("It looks like you're trying to connect to an oldstyle server with a named export. This won't work.");
 255                         }
 256                 }
 257                 printf(".");
 258                 if(read(sock, &tmp, sizeof(uint16_t)) < 0) {
 259                         err("Failed reading flags: %m");
 260                 }
 261                 *flags = ((u32)ntohs(tmp));
 262                 if((needed_flags & *flags) != needed_flags) {
 263                         /* There's currently really only one reason why this
 264                          * check could possibly fail, but we may need to change
 265                          * this error message in the future... */
 266                         fprintf(stderr, "\nE: Server does not support listing exports\n");
 267                         exit(EXIT_FAILURE);
 268                 }
 269
 270                 client_flags = htonl(client_flags);
 271                 if (write(sock, &client_flags, sizeof(client_flags)) < 0)
 272                         err("Failed/2.1: %m");
 273
 274                 if(do_opts & NBDC_DO_LIST) {
 275                         ask_list(sock);
 276                         exit(EXIT_SUCCESS);
 277                 }
 278
 279                 /* Write the export name that we're after */
 280                 magic = htonll(opts_magic);
 281                 if (write(sock, &magic, sizeof(magic)) < 0)
 282                         err("Failed/2.2: %m");
 283
 284                 opt = ntohl(NBD_OPT_EXPORT_NAME);
 285                 if (write(sock, &opt, sizeof(opt)) < 0)
 286                         err("Failed/2.3: %m");
 287                 namesize = (u32)strlen(name);
 288                 namesize = ntohl(namesize);
 289                 if (write(sock, &namesize, sizeof(namesize)) < 0)
 290                         err("Failed/2.4: %m");
 291                 if (write(sock, name, strlen(name)) < 0)
 292                         err("Failed/2.4: %m");
 293         } else {
 294                 if (magic != cliserv_magic) {
 295                         if(magic != opts_magic)
 296                                 err("Not enough cliserv_magic");
 297                         else
 298                                 err("It looks like you're trying to connect to a newstyle server with the oldstyle protocol. Try the -N option.");
 299                 }
 300                 printf(".");
 301         }
 302
 303         if (read(sock, &size64, sizeof(size64)) <= 0) {
 304                 if (!errno)
 305                         err("Server closed connection");
 306                 err("Failed/3: %m\n");
 307         }
 308         size64 = ntohll(size64);
 309
 310         if ((size64>>12) > (uint64_t)~0UL) {
 311                 printf("size = %luMB", (unsigned long)(size64>>20));
 312                 err("Exported device is too big for me. Get 64-bit machine :-(\n");
 313         } else
 314                 printf("size = %luMB", (unsigned long)(size64>>20));
 315
 316         if(!name) {
 317                 if (read(sock, flags, sizeof(*flags)) < 0)
 318                         err("Failed/4: %m\n");
 319                 *flags = ntohl(*flags);
 320         } else {
 321                 if(read(sock, &tmp, sizeof(tmp)) < 0)
 322                         err("Failed/4: %m\n");
 323                 *flags |= (uint32_t)ntohs(tmp);
 324         }
 325
 326         if (read(sock, &buf, 124) < 0)
 327                 err("Failed/5: %m\n");
 328         printf("\n");
 329
 330         *rsize64 = size64;
 331 }
 332
 333 void setsizes(int nbd, u64 size64, int blocksize, u32 flags) {
 334         unsigned long size;
 335         int read_only = (flags & NBD_FLAG_READ_ONLY) ? 1 : 0;
 336
 337         if (size64>>12 > (uint64_t)~0UL)
 338                 err("Device too large.\n");
 339         else {
 340                 if (ioctl(nbd, NBD_SET_BLKSIZE, 4096UL) < 0)
 341                         err("Ioctl/1.1a failed: %m\n");
 342                 size = (unsigned long)(size64>>12);
 343                 if (ioctl(nbd, NBD_SET_SIZE_BLOCKS, size) < 0)
 344                         err("Ioctl/1.1b failed: %m\n");
 345                 if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long)blocksize) < 0)
 346                         err("Ioctl/1.1c failed: %m\n");
 347                 fprintf(stderr, "bs=%d, sz=%llu bytes\n", blocksize, 4096ULL*size);
 348         }
 349
 350         ioctl(nbd, NBD_CLEAR_SOCK);
 351
 352         /* ignore error as kernel may not support */
 353         ioctl(nbd, NBD_SET_FLAGS, (unsigned long) flags);
 354
 355         if (ioctl(nbd, BLKROSET, (unsigned long) &read_only) < 0)
 356                 err("Unable to set read-only attribute for device");
 357 }
 358
 359 void set_timeout(int nbd, int timeout) {
 360         if (timeout) {
 361                 if (ioctl(nbd, NBD_SET_TIMEOUT, (unsigned long)timeout) < 0)
 362                         err("Ioctl NBD_SET_TIMEOUT failed: %m\n");
 363                 fprintf(stderr, "timeout=%d\n", timeout);
 364         }
 365 }
 366
 367 void finish_sock(int sock, int nbd, int swap) {
 368         if (ioctl(nbd, NBD_SET_SOCK, sock) < 0)
 369                 err("Ioctl NBD_SET_SOCK failed: %m\n");
 370
 371         if (swap)
 372                 mlockall(MCL_CURRENT | MCL_FUTURE);
 373 }
 374
 375 static int
 376 oom_adjust(const char *file, const char *value)
 377 {
 378         int fd, rc;
 379         size_t len;
 380
 381         fd = open(file, O_WRONLY);
 382         if (fd < 0)
 383                 return -1;
 384         len = strlen(value);
 385         rc = write(fd, value, len) != (ssize_t) len;
 386         close(fd);
 387         return rc ? -1 : 0;
 388 }
 389
 390 void usage(char* errmsg, ...) {
 391         if(errmsg) {
 392                 char tmp[256];
 393                 va_list ap;
 394                 va_start(ap, errmsg);
 395                 snprintf(tmp, 256, "ERROR: %s\n\n", errmsg);
 396                 vfprintf(stderr, tmp, ap);
 397                 va_end(ap);
 398         } else {
 399                 fprintf(stderr, "nbd-client version %s\n", PACKAGE_VERSION);
 400         }
 401         fprintf(stderr, "Usage: nbd-client host port nbd_device [-block-size|-b block size] [-timeout|-t timeout] [-swap|-s] [-sdp|-S] [-persist|-p] [-nofork|-n] [-systemd-mark|-m]\n");
 402         fprintf(stderr, "Or   : nbd-client -name|-N name host [port] nbd_device [-block-size|-b block size] [-timeout|-t timeout] [-swap|-s] [-sdp|-S] [-persist|-p] [-nofork|-n]\n");
 403         fprintf(stderr, "Or   : nbd-client -d nbd_device\n");
 404         fprintf(stderr, "Or   : nbd-client -c nbd_device\n");
 405         fprintf(stderr, "Or   : nbd-client -h|--help\n");
 406         fprintf(stderr, "Or   : nbd-client -l|--list host\n");
 407         fprintf(stderr, "Default value for blocksize is 1024 (recommended for ethernet)\n");
 408         fprintf(stderr, "Allowed values for blocksize are 512,1024,2048,4096\n"); /* will be checked in kernel :) */
 409         fprintf(stderr, "Note, that kernel 2.4.2 and older ones do not work correctly with\n");
 410         fprintf(stderr, "blocksizes other than 1024 without patches\n");
 411         fprintf(stderr, "Default value for port with -N is 10809. Note that port must always be numeric\n");
 412 }
 413
 414 void disconnect(char* device) {
 415         int nbd = open(device, O_RDWR);
 416
 417         if (nbd < 0)
 418                 err("Cannot open NBD: %m\nPlease ensure the 'nbd' module is loaded.");
 419         printf("disconnect, ");
 420         if (ioctl(nbd, NBD_DISCONNECT)<0)
 421                 err("Ioctl failed: %m\n");
 422         printf("sock, ");
 423         if (ioctl(nbd, NBD_CLEAR_SOCK)<0)
 424                 err("Ioctl failed: %m\n");
 425         printf("done\n");
 426 }
 427
 428 int main(int argc, char *argv[]) {
 429         char* port=NULL;
 430         int sock, nbd;
 431         int blocksize=1024;
 432         char *hostname=NULL;
 433         char *nbddev=NULL;
 434         int swap=0;
 435         int cont=0;
 436         int timeout=0;
 437         int sdp=0;
 438         int G_GNUC_UNUSED nofork=0; // if -dNOFORK
 439         u64 size64;
 440         u32 flags;
 441         int c;
 442         int nonspecial=0;
 443         char* name=NULL;
 444         uint32_t needed_flags=0;
 445         uint32_t cflags=0;
 446         uint32_t opts=0;
 447         sigset_t block, old;
 448         struct sigaction sa;
 449         struct option long_options[] = {
 450                 { "block-size", required_argument, NULL, 'b' },
 451                 { "check", required_argument, NULL, 'c' },
 452                 { "disconnect", required_argument, NULL, 'd' },
 453                 { "help", no_argument, NULL, 'h' },
 454                 { "list", no_argument, NULL, 'l' },
 455                 { "name", required_argument, NULL, 'N' },
 456                 { "nofork", no_argument, NULL, 'n' },
 457                 { "persist", no_argument, NULL, 'p' },
 458                 { "sdp", no_argument, NULL, 'S' },
 459                 { "swap", no_argument, NULL, 's' },
 460                 { "systemd-mark", no_argument, NULL, 'm' },
 461                 { "timeout", required_argument, NULL, 't' },
 462                 { 0, 0, 0, 0 },
 463         };
 464
 465         logging();
 466
 467         while((c=getopt_long_only(argc, argv, "-b:c:d:hlnN:pSst:", long_options, NULL))>=0) {
 468                 switch(c) {
 469                 case 1:
 470                         // non-option argument
 471                         if(strchr(optarg, '=')) {
 472                                 // old-style 'bs=' or 'timeout='
 473                                 // argument
 474                                 fprintf(stderr, "WARNING: old-style command-line argument encountered. This is deprecated.\n");
 475                                 if(!strncmp(optarg, "bs=", 3)) {
 476                                         optarg+=3;
 477                                         goto blocksize;
 478                                 }
 479                                 if(!strncmp(optarg, "timeout=", 8)) {
 480                                         optarg+=8;
 481                                         goto timeout;
 482                                 }
 483                                 usage("unknown option %s encountered", optarg);
 484                                 exit(EXIT_FAILURE);
 485                         }
 486                         switch(nonspecial++) {
 487                                 case 0:
 488                                         // host
 489                                         hostname=optarg;
 490                                         break;
 491                                 case 1:
 492                                         // port
 493                                         if(!strtol(optarg, NULL, 0)) {
 494                                                 // not parseable as a number, assume it's the device and we have a name
 495                                                 nbddev = optarg;
 496                                                 nonspecial++;
 497                                         } else {
 498                                                 port = optarg;
 499                                         }
 500                                         break;
 501                                 case 2:
 502                                         // device
 503                                         nbddev = optarg;
 504                                         break;
 505                                 default:
 506                                         usage("too many non-option arguments specified");
 507                                         exit(EXIT_FAILURE);
 508                         }
 509                         break;
 510                 case 'b':
 511                       blocksize:
 512                         blocksize=(int)strtol(optarg, NULL, 0);
 513                         break;
 514                 case 'c':
 515                         return check_conn(optarg, 1);
 516                 case 'd':
 517                         disconnect(optarg);
 518                         exit(EXIT_SUCCESS);
 519                 case 'h':
 520                         usage(NULL);
 521                         exit(EXIT_SUCCESS);
 522                 case 'l':
 523                         needed_flags |= NBD_FLAG_FIXED_NEWSTYLE;
 524                         cflags |= NBD_FLAG_C_FIXED_NEWSTYLE;
 525                         opts |= NBDC_DO_LIST;
 526                         name="";
 527                         nbddev="";
 528                         port = NBD_DEFAULT_PORT;
 529                         break;
 530                 case 'm':
 531                         argv[0][0] = '@';
 532                         break;
 533                 case 'n':
 534                         nofork=1;
 535                         break;
 536                 case 'N':
 537                         name=optarg;
 538                         if(!port) {
 539                                 port = NBD_DEFAULT_PORT;
 540                         }
 541                         break;
 542                 case 'p':
 543                         cont=1;
 544                         break;
 545                 case 's':
 546                         swap=1;
 547                         break;
 548                 case 'S':
 549                         sdp=1;
 550                         break;
 551                 case 't':
 552                       timeout:
 553                         timeout=strtol(optarg, NULL, 0);
 554                         break;
 555                 default:
 556                         fprintf(stderr, "E: option eaten by 42 mice\n");
 557                         exit(EXIT_FAILURE);
 558                 }
 559         }
 560
 561         if((!port && !name) || !hostname || !nbddev) {
 562                 usage("not enough information specified");
 563                 exit(EXIT_FAILURE);
 564         }
 565
 566         sock = opennet(hostname, port, sdp);
 567         if (sock < 0)
 568                 exit(EXIT_FAILURE);
 569
 570         negotiate(sock, &size64, &flags, name, needed_flags, cflags, opts);
 571
 572         nbd = open(nbddev, O_RDWR);
 573         if (nbd < 0)
 574           err("Cannot open NBD: %m\nPlease ensure the 'nbd' module is loaded.");
 575
 576         setsizes(nbd, size64, blocksize, flags);
 577         set_timeout(nbd, timeout);
 578         finish_sock(sock, nbd, swap);
 579         if (swap) {
 580                 /* try linux >= 2.6.36 interface first */
 581                 if (oom_adjust("/proc/self/oom_score_adj", "-1000")) {
 582                         /* fall back to linux <= 2.6.35 interface */
 583                         oom_adjust("/proc/self/oom_adj", "-17");
 584                 }
 585         }
 586
 587         /* Go daemon */
 588
 589 #ifndef NOFORK
 590         if(!nofork) {
 591                 if (daemon(0,0) < 0)
 592                         err("Cannot detach from terminal");
 593         }
 594
 595         memset(&sa, 0, sizeof(sa));
 596         sa.sa_handler = SIG_IGN;
 597         sigaction(SIGCHLD, &sa, NULL);
 598 #endif
 599         do {
 600 #ifndef NOFORK
 601
 602                 sigfillset(&block);
 603                 sigdelset(&block, SIGKILL);
 604                 sigdelset(&block, SIGTERM);
 605                 sigdelset(&block, SIGPIPE);
 606                 sigprocmask(SIG_SETMASK, &block, &old);
 607
 608                 if (!fork()) {
 609                         /* Due to a race, the kernel NBD driver cannot
 610                          * call for a reread of the partition table
 611                          * in the handling of the NBD_DO_IT ioctl().
 612                          * Therefore, this is done in the first open()
 613                          * of the device. We therefore make sure that
 614                          * the device is opened at least once after the
 615                          * connection was made. This has to be done in a
 616                          * separate process, since the NBD_DO_IT ioctl()
 617                          * does not return until the NBD device has
 618                          * disconnected.
 619                          */
 620                         while(check_conn(nbddev, 0)) {
 621                                 sleep(1);
 622                         }
 623                         open(nbddev, O_RDONLY);
 624                         exit(0);
 625                 }
 626 #endif
 627
 628                 if (ioctl(nbd, NBD_DO_IT) < 0) {
 629                         int error = errno;
 630                         fprintf(stderr, "nbd,%d: Kernel call returned: %d", getpid(), error);
 631                         if(error==EBADR) {
 632                                 /* The user probably did 'nbd-client -d' on us.
 633                                  * quit */
 634                                 cont=0;
 635                         } else {
 636                                 if(cont) {
 637                                         u64 new_size;
 638                                         u32 new_flags;
 639
 640                                         close(sock); close(nbd);
 641                                         for (;;) {
 642                                                 fprintf(stderr, " Reconnecting\n");
 643                                                 sock = opennet(hostname, port, sdp);
 644                                                 if (sock >= 0)
 645                                                         break;
 646                                                 sleep (1);
 647                                         }
 648                                         nbd = open(nbddev, O_RDWR);
 649                                         if (nbd < 0)
 650                                                 err("Cannot open NBD: %m");
 651                                         negotiate(sock, &new_size, &new_flags, name, needed_flags, cflags, opts);
 652                                         if (size64 != new_size) {
 653                                                 err("Size of the device changed. Bye");
 654                                         }
 655                                         setsizes(nbd, size64, blocksize,
 656                                                                 new_flags);
 657
 658                                         set_timeout(nbd, timeout);
 659                                         finish_sock(sock,nbd,swap);
 660                                 }
 661                         }
 662                 } else {
 663                         /* We're on 2.4. It's not clearly defined what exactly
 664                          * happened at this point. Probably best to quit, now
 665                          */
 666                         fprintf(stderr, "Kernel call returned.");
 667                         cont=0;
 668                 }
 669         } while(cont);
 670         printf("sock, ");
 671         ioctl(nbd, NBD_CLEAR_SOCK);
 672         printf("done\n");
 673         return 0;
 674 }