LXR busybox/networking/nbd-client.c

   1/*
   2 * Copyright 2010 Rob Landley <rob@landley.net>
   3 *
   4 * Licensed under GPLv2, see file LICENSE in this source tree.
   5 */
   6//config:config NBDCLIENT
   7//config:       bool "nbd-client (6 kb)"
   8//config:       default y
   9//config:       help
  10//config:       Network block device client
  11
  12//applet:IF_NBDCLIENT(APPLET_NOEXEC(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
  13
  14//kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
  15
  16#include "libbb.h"
  17#include <netinet/tcp.h>
  18#include <linux/fs.h>
  19#include <getopt.h>
  20
  21#define NBD_SET_SOCK          _IO(0xab, 0)
  22#define NBD_SET_BLKSIZE       _IO(0xab, 1)
  23#define NBD_SET_SIZE          _IO(0xab, 2)
  24#define NBD_DO_IT             _IO(0xab, 3)
  25#define NBD_CLEAR_SOCK        _IO(0xab, 4)
  26#define NBD_CLEAR_QUEUE       _IO(0xab, 5)
  27#define NBD_PRINT_DEBUG       _IO(0xab, 6)
  28#define NBD_SET_SIZE_BLOCKS   _IO(0xab, 7)
  29#define NBD_DISCONNECT        _IO(0xab, 8)
  30#define NBD_SET_TIMEOUT       _IO(0xab, 9)
  31#define NBD_SET_FLAGS         _IO(0xab, 10)
  32
  33//usage:#define nbdclient_trivial_usage
  34//usage:       "{ [-b BLKSIZE] [-N NAME] [-t SEC] [-p] HOST [PORT] | -d } BLOCKDEV"
  35//usage:#define nbdclient_full_usage "\n\n"
  36//usage:       "Connect to HOST and provide network block device on BLOCKDEV"
  37
  38//TODO: more compat with nbd-client version 3.17 -
  39//nbd-client host [ port ] nbd-device [ -connections num ] [ -sdp ] [ -swap ]
  40//      [ -persist ] [ -nofork ] [ -nonetlink ] [ -systemd-mark ]
  41//      [ -block-size block size ] [ -timeout seconds ] [ -name name ]
  42//      [ -certfile certfile ] [ -keyfile keyfile ] [ -cacertfile cacertfile ]
  43//      [ -tlshostname hostname ]
  44//nbd-client -unix path nbd-device [ -connections num ] [ -sdp ] [ -swap ]
  45//      [ -persist ] [ -nofork ] [ -nonetlink ] [ -systemd-mark ]
  46//      [ -block-size block size ] [ -timeout seconds ] [ -name name ]
  47//nbd-client nbd-device
  48//nbd-client -d nbd-device
  49//nbd-client -c nbd-device
  50//nbd-client -l host [ port ]
  51//nbd-client [ -netlink ] -l host
  52//
  53//Default value for blocksize is 4096
  54//Allowed values for blocksize are 512,1024,2048,4096
  55
  56int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  57int nbdclient_main(int argc, char **argv)
  58{
  59#if BB_MMU
  60        bool nofork;
  61#endif
  62        bool opt_d;
  63        bool opt_p;
  64        const char *host, *port, *device;
  65        const char *name;
  66        unsigned blksize, size_blocks;
  67        unsigned timeout;
  68        int ch;
  69        struct nbd_header_t {
  70                uint64_t magic1; // "NBDMAGIC"
  71                uint64_t magic2; // old style: 0x420281861253 big endian
  72                //               // new style: 0x49484156454F5054 (IHAVEOPT)
  73        } nbd_header;
  74        struct old_nbd_header_t {
  75                uint64_t devsize;
  76                uint32_t flags;
  77                char data[124];
  78        } old_nbd_header;
  79        struct new_nbd_header_t {
  80                uint64_t devsize;
  81                uint16_t transmission_flags;
  82                char data[124];
  83        } new_nbd_header;
  84        struct nbd_opt_t {
  85                uint64_t magic;
  86                uint32_t opt;
  87                uint32_t len;
  88        } nbd_opts;
  89
  90        static const struct option long_options[] = {
  91                { "block-size", required_argument, NULL, 'b' },
  92                { "timeout"   , required_argument, NULL, 't' },
  93                { "name"      , required_argument, NULL, 'n' },
  94                { "persist"   , no_argument      , NULL, 'p' },
  95                { NULL }
  96        };
  97
  98        BUILD_BUG_ON(offsetof(struct old_nbd_header_t, data) != 8 + 4);
  99        BUILD_BUG_ON(offsetof(struct new_nbd_header_t, data) != 8 + 2);
 100
 101#if !BB_MMU
 102        bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
 103#endif
 104
 105        // Parse args. nbd-client uses stupid "one-dash long options" style :(
 106        // Even though short forms (-b,-t,-N,-p) exist for all long opts,
 107        // older manpages only contained long forms, which probably resulted
 108        // in many scripts using them.
 109        blksize = 4096;
 110        timeout = 0;
 111        name = ""; // use of "" instead of NULL simplifies strlen() later
 112        opt_d = opt_p = 0;
 113        while ((ch = getopt_long_only(argc, argv, "dN:", long_options, NULL)) != -1) {
 114                switch (ch) {
 115                case 'p':       // -persist
 116                        opt_p = 1;
 117                        break;
 118                case 'd':       // -d
 119                        opt_d = 1;
 120                        break;
 121                case 'b':       // -block-size
 122                        blksize = xatou(optarg);
 123                        break;
 124                case 't':       // -timeout
 125                        timeout = xatou(optarg);
 126                        break;
 127                case 'N':       // -N
 128                case 'n':       // -name
 129                        name = optarg;
 130                        break;
 131                default:
 132                        bb_show_usage();
 133                }
 134        }
 135        argv += optind;
 136
 137        if (opt_d) { // -d
 138                if (argv[0] && !argv[1]) {
 139                        int nbd = xopen(argv[0], O_RDWR);
 140                        ioctl(nbd, NBD_DISCONNECT);
 141                        ioctl(nbd, NBD_CLEAR_SOCK);
 142                        if (ENABLE_FEATURE_CLEAN_UP)
 143                                close(nbd);
 144                        return 0;
 145                }
 146                bb_show_usage();
 147        }
 148
 149        // Allow only argv[] of: HOST [PORT] BLOCKDEV
 150        if (!argv[0] || !argv[1] || (argv[2] && argv[3])) {
 151                bb_show_usage();
 152        }
 153
 154        host = argv[0];
 155        port = argv[2] ? argv[1] : "10809";
 156        device = argv[2] ? argv[2] : argv[1];
 157
 158        // Repeat until spanked if -persist
 159#if BB_MMU
 160        nofork = 0;
 161#endif
 162        do {
 163                int sock, nbd;
 164                int ro;
 165                int proto_new; // 0 for old, 1 for new
 166#if BB_MMU
 167                char *data;
 168#endif
 169
 170                // Make sure BLOCKDEV exists
 171                nbd = xopen(device, O_RDWR);
 172
 173                // Find and connect to server
 174                sock = create_and_connect_stream_or_die(host, xatou16(port));
 175                setsockopt_1(sock, IPPROTO_TCP, TCP_NODELAY);
 176
 177                // Log on to the server
 178                xread(sock, &nbd_header, 8 + 8);
 179                if (memcmp(&nbd_header.magic1, "NBDMAGIC",
 180                                sizeof(nbd_header.magic1)) != 0
 181                ) {
 182                        bb_error_msg_and_die("login failed");
 183                }
 184                if (memcmp(&nbd_header.magic2,
 185                                "\x00\x00\x42\x02\x81\x86\x12\x53",
 186                                sizeof(nbd_header.magic2)) == 0
 187                ) {
 188                        proto_new = 0;
 189                } else if (memcmp(&nbd_header.magic2, "IHAVEOPT", 8) == 0) {
 190                        proto_new = 1;
 191                } else {
 192                        bb_error_msg_and_die("login failed");
 193                }
 194
 195                if (!proto_new) {
 196                        xread(sock, &old_nbd_header,
 197                                        sizeof(old_nbd_header.devsize) +
 198                                        sizeof(old_nbd_header.flags) +
 199                                        sizeof(old_nbd_header.data));
 200                        size_blocks = SWAP_BE64(old_nbd_header.devsize) / blksize;
 201                        ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long) blksize);
 202                        ioctl(nbd, NBD_SET_SIZE_BLOCKS, size_blocks);
 203                        ioctl(nbd, NBD_CLEAR_SOCK);
 204                        ro = !!(old_nbd_header.flags & htons(2));
 205#if BB_MMU
 206                        data = old_nbd_header.data;
 207#endif
 208                } else {
 209                        unsigned namelen;
 210                        uint16_t handshake_flags;
 211
 212                        xread(sock, &handshake_flags, sizeof(handshake_flags));
 213                        xwrite(sock, &const_int_0, sizeof(const_int_0)); // client_flags
 214
 215                        memcpy(&nbd_opts.magic, "IHAVEOPT",
 216                                        sizeof(nbd_opts.magic));
 217                        nbd_opts.opt = htonl(1); // NBD_OPT_EXPORT_NAME
 218                        namelen = strlen(name);
 219                        nbd_opts.len = htonl(namelen);
 220                        xwrite(sock, &nbd_opts,
 221                                        sizeof(nbd_opts.magic) +
 222                                        sizeof(nbd_opts.opt) +
 223                                        sizeof(nbd_opts.len));
 224                        xwrite(sock, name, namelen);
 225
 226                        xread(sock, &new_nbd_header,
 227                                        sizeof(new_nbd_header.devsize) +
 228                                        sizeof(new_nbd_header.transmission_flags) +
 229                                        sizeof(new_nbd_header.data));
 230                        size_blocks = SWAP_BE64(new_nbd_header.devsize) / blksize;
 231                        ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long) blksize);
 232                        ioctl(nbd, NBD_SET_SIZE_BLOCKS, size_blocks);
 233                        ioctl(nbd, NBD_CLEAR_SOCK);
 234                        ioctl(nbd, NBD_SET_FLAGS,
 235                                        ntohs(new_nbd_header.transmission_flags));
 236                        ro = !!(new_nbd_header.transmission_flags & htons(2));
 237#if BB_MMU
 238                        data = new_nbd_header.data;
 239#endif
 240                }
 241
 242                if (ioctl(nbd, BLKROSET, &ro) < 0) {
 243                        bb_perror_msg_and_die("BLKROSET");
 244                }
 245
 246                if (timeout) {
 247                        if (ioctl(nbd, NBD_SET_TIMEOUT, (unsigned long) timeout)) {
 248                                bb_perror_msg_and_die("NBD_SET_TIMEOUT");
 249                        }
 250                }
 251
 252                if (ioctl(nbd, NBD_SET_SOCK, sock)) {
 253                        bb_perror_msg_and_die("NBD_SET_SOCK");
 254                }
 255
 256                //if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
 257#if BB_MMU
 258                // Open the device to force reread of the partition table.
 259                // Need to do it in a separate process, since open(device)
 260                // needs some other process to sit in ioctl(nbd, NBD_DO_IT).
 261                if (fork() == 0) {
 262                        /* child */
 263                        char *s = strrchr(device, '/');
 264                        sprintf(data, "/sys/block/%.32s/pid", s ? s + 1 : device);
 265                        // Is it up yet?
 266                        for (;;) {
 267                                int fd = open(data, O_RDONLY);
 268                                if (fd >= 0) {
 269                                        if (ENABLE_FEATURE_CLEAN_UP)
 270                                                close(fd);
 271                                        break;
 272                                }
 273                                sleep(1);
 274                        }
 275                        open(device, O_RDONLY);
 276                        return 0;
 277                }
 278
 279                // Daemonize here
 280                if (!nofork) {
 281                        daemon(0, 0);
 282                        nofork = 1;
 283                }
 284#endif
 285                // This turns us (the process that calls this ioctl)
 286                // into a dedicated NBD request handler.
 287                // We block here for a long time.
 288                // When exactly ioctl returns? On a signal,
 289                // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d].
 290                if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) {
 291                        // Flush queue and exit
 292                        ioctl(nbd, NBD_CLEAR_QUEUE);
 293                        ioctl(nbd, NBD_CLEAR_SOCK);
 294                        break;
 295                }
 296
 297                close(sock);
 298                close(nbd);
 299        } while (opt_p);
 300
 301        return 0;
 302}
 303