[2725] | 1 | /*
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| 2 | * Copyright 2010 Rob Landley <rob@landley.net>
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| 3 | *
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| 4 | * Licensed under GPLv2, see file LICENSE in this source tree.
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| 5 | */
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| 6 | #include "libbb.h"
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| 7 | #include <netinet/tcp.h>
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| 8 | #include <linux/fs.h>
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| 9 |
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[3232] | 10 | //applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
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[2725] | 11 |
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| 12 | //kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o
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| 13 |
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| 14 | //config:config NBDCLIENT
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| 15 | //config: bool "nbd-client"
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| 16 | //config: default y
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| 17 | //config: help
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| 18 | //config: Network block device client
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| 19 |
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| 20 | #define NBD_SET_SOCK _IO(0xab, 0)
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| 21 | #define NBD_SET_BLKSIZE _IO(0xab, 1)
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| 22 | #define NBD_SET_SIZE _IO(0xab, 2)
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| 23 | #define NBD_DO_IT _IO(0xab, 3)
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| 24 | #define NBD_CLEAR_SOCK _IO(0xab, 4)
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| 25 | #define NBD_CLEAR_QUEUE _IO(0xab, 5)
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| 26 | #define NBD_PRINT_DEBUG _IO(0xab, 6)
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| 27 | #define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
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| 28 | #define NBD_DISCONNECT _IO(0xab, 8)
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| 29 | #define NBD_SET_TIMEOUT _IO(0xab, 9)
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| 30 |
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| 31 | //usage:#define nbdclient_trivial_usage
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| 32 | //usage: "HOST PORT BLOCKDEV"
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| 33 | //usage:#define nbdclient_full_usage "\n\n"
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| 34 | //usage: "Connect to HOST and provide a network block device on BLOCKDEV"
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| 35 |
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| 36 | //TODO: more compat with nbd-client version 2.9.13 -
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| 37 | //Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist] [-nofork]
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| 38 | //Or : nbd-client -d nbd_device
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| 39 | //Or : nbd-client -c nbd_device
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| 40 | //Default value for blocksize is 1024 (recommended for ethernet)
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| 41 | //Allowed values for blocksize are 512,1024,2048,4096
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| 42 | //Note, that kernel 2.4.2 and older ones do not work correctly with
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| 43 | //blocksizes other than 1024 without patches
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| 44 |
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| 45 | int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 46 | int nbdclient_main(int argc, char **argv)
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| 47 | {
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| 48 | unsigned long timeout = 0;
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| 49 | #if BB_MMU
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| 50 | int nofork = 0;
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| 51 | #endif
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| 52 | char *host, *port, *device;
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| 53 | struct nbd_header_t {
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| 54 | uint64_t magic1; // "NBDMAGIC"
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| 55 | uint64_t magic2; // 0x420281861253 big endian
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| 56 | uint64_t devsize;
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| 57 | uint32_t flags;
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| 58 | char data[124];
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| 59 | } nbd_header;
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| 60 | struct bug_check {
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| 61 | char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1];
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| 62 | };
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| 63 |
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| 64 | // Parse command line stuff (just a stub now)
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| 65 | if (argc != 4)
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| 66 | bb_show_usage();
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| 67 |
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| 68 | #if !BB_MMU
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| 69 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
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| 70 | #endif
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| 71 |
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| 72 | host = argv[1];
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| 73 | port = argv[2];
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| 74 | device = argv[3];
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| 75 |
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| 76 | // Repeat until spanked (-persist behavior)
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| 77 | for (;;) {
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| 78 | int sock, nbd;
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| 79 | int ro;
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| 80 |
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| 81 | // Make sure the /dev/nbd exists
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| 82 | nbd = xopen(device, O_RDWR);
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| 83 |
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| 84 | // Find and connect to server
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| 85 | sock = create_and_connect_stream_or_die(host, xatou16(port));
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| 86 | setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1));
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| 87 |
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| 88 | // Log on to the server
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| 89 | xread(sock, &nbd_header, 8+8+8+4 + 124);
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| 90 | if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0)
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| 91 | bb_error_msg_and_die("login failed");
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| 92 |
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| 93 | // Set 4k block size. Everything uses that these days
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| 94 | ioctl(nbd, NBD_SET_BLKSIZE, 4096);
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| 95 | ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096);
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| 96 | ioctl(nbd, NBD_CLEAR_SOCK);
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| 97 |
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| 98 | // If the sucker was exported read only, respect that locally
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| 99 | ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2);
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| 100 | if (ioctl(nbd, BLKROSET, &ro) < 0)
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| 101 | bb_perror_msg_and_die("BLKROSET");
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| 102 |
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| 103 | if (timeout)
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| 104 | if (ioctl(nbd, NBD_SET_TIMEOUT, timeout))
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| 105 | bb_perror_msg_and_die("NBD_SET_TIMEOUT");
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| 106 | if (ioctl(nbd, NBD_SET_SOCK, sock))
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| 107 | bb_perror_msg_and_die("NBD_SET_SOCK");
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| 108 |
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| 109 | // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
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| 110 |
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| 111 | #if BB_MMU
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| 112 | // Open the device to force reread of the partition table.
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| 113 | // Need to do it in a separate process, since open(device)
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| 114 | // needs some other process to sit in ioctl(nbd, NBD_DO_IT).
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| 115 | if (fork() == 0) {
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| 116 | char *s = strrchr(device, '/');
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| 117 | sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device);
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| 118 | // Is it up yet?
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| 119 | for (;;) {
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| 120 | int fd = open(nbd_header.data, O_RDONLY);
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| 121 | if (fd >= 0) {
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| 122 | //close(fd);
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| 123 | break;
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| 124 | }
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| 125 | sleep(1);
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| 126 | }
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| 127 | open(device, O_RDONLY);
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| 128 | return 0;
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| 129 | }
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| 130 |
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| 131 | // Daemonize here
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| 132 | if (!nofork) {
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| 133 | daemon(0, 0);
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| 134 | nofork = 1;
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| 135 | }
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| 136 | #endif
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| 137 |
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| 138 | // This turns us (the process that calls this ioctl)
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| 139 | // into a dedicated NBD request handler.
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| 140 | // We block here for a long time.
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| 141 | // When exactly ioctl returns? On a signal,
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| 142 | // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d].
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| 143 | if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) {
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| 144 | // Flush queue and exit
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| 145 | ioctl(nbd, NBD_CLEAR_QUEUE);
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| 146 | ioctl(nbd, NBD_CLEAR_SOCK);
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| 147 | break;
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| 148 | }
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| 149 |
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| 150 | close(sock);
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| 151 | close(nbd);
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| 152 | }
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| 153 |
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| 154 | return 0;
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| 155 | }
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