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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10 | //applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient))
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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 |
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61 | BUILD_BUG_ON(offsetof(struct nbd_header_t, data) != 8+8+8+4);
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62 |
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63 | // Parse command line stuff (just a stub now)
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64 | if (argc != 4)
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65 | bb_show_usage();
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66 |
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67 | #if !BB_MMU
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68 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv);
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69 | #endif
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70 |
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71 | host = argv[1];
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72 | port = argv[2];
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73 | device = argv[3];
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74 |
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75 | // Repeat until spanked (-persist behavior)
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76 | for (;;) {
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77 | int sock, nbd;
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78 | int ro;
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79 |
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80 | // Make sure the /dev/nbd exists
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81 | nbd = xopen(device, O_RDWR);
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82 |
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83 | // Find and connect to server
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84 | sock = create_and_connect_stream_or_die(host, xatou16(port));
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85 | setsockopt_1(sock, IPPROTO_TCP, TCP_NODELAY);
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86 |
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87 | // Log on to the server
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88 | xread(sock, &nbd_header, 8+8+8+4 + 124);
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89 | if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0)
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90 | bb_error_msg_and_die("login failed");
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91 |
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92 | // Set 4k block size. Everything uses that these days
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93 | ioctl(nbd, NBD_SET_BLKSIZE, 4096);
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94 | ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096);
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95 | ioctl(nbd, NBD_CLEAR_SOCK);
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96 |
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97 | // If the sucker was exported read only, respect that locally
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98 | ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2);
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99 | if (ioctl(nbd, BLKROSET, &ro) < 0)
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100 | bb_perror_msg_and_die("BLKROSET");
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101 |
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102 | if (timeout)
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103 | if (ioctl(nbd, NBD_SET_TIMEOUT, timeout))
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104 | bb_perror_msg_and_die("NBD_SET_TIMEOUT");
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105 | if (ioctl(nbd, NBD_SET_SOCK, sock))
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106 | bb_perror_msg_and_die("NBD_SET_SOCK");
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107 |
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108 | // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE);
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109 |
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110 | #if BB_MMU
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111 | // Open the device to force reread of the partition table.
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112 | // Need to do it in a separate process, since open(device)
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113 | // needs some other process to sit in ioctl(nbd, NBD_DO_IT).
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114 | if (fork() == 0) {
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115 | char *s = strrchr(device, '/');
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116 | sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device);
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117 | // Is it up yet?
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118 | for (;;) {
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119 | int fd = open(nbd_header.data, O_RDONLY);
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120 | if (fd >= 0) {
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121 | //close(fd);
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122 | break;
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123 | }
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124 | sleep(1);
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125 | }
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126 | open(device, O_RDONLY);
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127 | return 0;
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128 | }
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129 |
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130 | // Daemonize here
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131 | if (!nofork) {
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132 | daemon(0, 0);
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133 | nofork = 1;
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134 | }
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135 | #endif
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136 |
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137 | // This turns us (the process that calls this ioctl)
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138 | // into a dedicated NBD request handler.
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139 | // We block here for a long time.
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140 | // When exactly ioctl returns? On a signal,
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141 | // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d].
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142 | if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) {
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143 | // Flush queue and exit
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144 | ioctl(nbd, NBD_CLEAR_QUEUE);
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145 | ioctl(nbd, NBD_CLEAR_SOCK);
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146 | break;
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147 | }
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148 |
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149 | close(sock);
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150 | close(nbd);
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151 | }
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152 |
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153 | return 0;
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154 | }
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