blob: 70869d6519fbb4cb9880d9cf98db2b6569560875
1 | /* |
2 | * Copyright 2010 Rob Landley <rob@landley.net> |
3 | * |
4 | * Licensed under GPLv2, see file LICENSE in this source tree. |
5 | */ |
6 | #include "libbb.h" |
7 | #include <netinet/tcp.h> |
8 | #include <linux/fs.h> |
9 | |
10 | //applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient)) |
11 | |
12 | //kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o |
13 | |
14 | //config:config NBDCLIENT |
15 | //config: bool "nbd-client" |
16 | //config: default y |
17 | //config: help |
18 | //config: Network block device client |
19 | |
20 | #define NBD_SET_SOCK _IO(0xab, 0) |
21 | #define NBD_SET_BLKSIZE _IO(0xab, 1) |
22 | #define NBD_SET_SIZE _IO(0xab, 2) |
23 | #define NBD_DO_IT _IO(0xab, 3) |
24 | #define NBD_CLEAR_SOCK _IO(0xab, 4) |
25 | #define NBD_CLEAR_QUEUE _IO(0xab, 5) |
26 | #define NBD_PRINT_DEBUG _IO(0xab, 6) |
27 | #define NBD_SET_SIZE_BLOCKS _IO(0xab, 7) |
28 | #define NBD_DISCONNECT _IO(0xab, 8) |
29 | #define NBD_SET_TIMEOUT _IO(0xab, 9) |
30 | |
31 | //usage:#define nbdclient_trivial_usage |
32 | //usage: "HOST PORT BLOCKDEV" |
33 | //usage:#define nbdclient_full_usage "\n\n" |
34 | //usage: "Connect to HOST and provide a network block device on BLOCKDEV" |
35 | |
36 | //TODO: more compat with nbd-client version 2.9.13 - |
37 | //Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist] [-nofork] |
38 | //Or : nbd-client -d nbd_device |
39 | //Or : nbd-client -c nbd_device |
40 | //Default value for blocksize is 1024 (recommended for ethernet) |
41 | //Allowed values for blocksize are 512,1024,2048,4096 |
42 | //Note, that kernel 2.4.2 and older ones do not work correctly with |
43 | //blocksizes other than 1024 without patches |
44 | |
45 | int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
46 | int nbdclient_main(int argc, char **argv) |
47 | { |
48 | unsigned long timeout = 0; |
49 | #if BB_MMU |
50 | int nofork = 0; |
51 | #endif |
52 | char *host, *port, *device; |
53 | struct nbd_header_t { |
54 | uint64_t magic1; // "NBDMAGIC" |
55 | uint64_t magic2; // 0x420281861253 big endian |
56 | uint64_t devsize; |
57 | uint32_t flags; |
58 | char data[124]; |
59 | } nbd_header; |
60 | |
61 | BUILD_BUG_ON(offsetof(struct nbd_header_t, data) != 8+8+8+4); |
62 | |
63 | // Parse command line stuff (just a stub now) |
64 | if (argc != 4) |
65 | bb_show_usage(); |
66 | |
67 | #if !BB_MMU |
68 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv); |
69 | #endif |
70 | |
71 | host = argv[1]; |
72 | port = argv[2]; |
73 | device = argv[3]; |
74 | |
75 | // Repeat until spanked (-persist behavior) |
76 | for (;;) { |
77 | int sock, nbd; |
78 | int ro; |
79 | |
80 | // Make sure the /dev/nbd exists |
81 | nbd = xopen(device, O_RDWR); |
82 | |
83 | // Find and connect to server |
84 | sock = create_and_connect_stream_or_die(host, xatou16(port)); |
85 | setsockopt_1(sock, IPPROTO_TCP, TCP_NODELAY); |
86 | |
87 | // Log on to the server |
88 | xread(sock, &nbd_header, 8+8+8+4 + 124); |
89 | if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0) |
90 | bb_error_msg_and_die("login failed"); |
91 | |
92 | // Set 4k block size. Everything uses that these days |
93 | ioctl(nbd, NBD_SET_BLKSIZE, 4096); |
94 | ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096); |
95 | ioctl(nbd, NBD_CLEAR_SOCK); |
96 | |
97 | // If the sucker was exported read only, respect that locally |
98 | ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2); |
99 | if (ioctl(nbd, BLKROSET, &ro) < 0) |
100 | bb_perror_msg_and_die("BLKROSET"); |
101 | |
102 | if (timeout) |
103 | if (ioctl(nbd, NBD_SET_TIMEOUT, timeout)) |
104 | bb_perror_msg_and_die("NBD_SET_TIMEOUT"); |
105 | if (ioctl(nbd, NBD_SET_SOCK, sock)) |
106 | bb_perror_msg_and_die("NBD_SET_SOCK"); |
107 | |
108 | // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE); |
109 | |
110 | #if BB_MMU |
111 | // Open the device to force reread of the partition table. |
112 | // Need to do it in a separate process, since open(device) |
113 | // needs some other process to sit in ioctl(nbd, NBD_DO_IT). |
114 | if (fork() == 0) { |
115 | char *s = strrchr(device, '/'); |
116 | sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device); |
117 | // Is it up yet? |
118 | for (;;) { |
119 | int fd = open(nbd_header.data, O_RDONLY); |
120 | if (fd >= 0) { |
121 | //close(fd); |
122 | break; |
123 | } |
124 | sleep(1); |
125 | } |
126 | open(device, O_RDONLY); |
127 | return 0; |
128 | } |
129 | |
130 | // Daemonize here |
131 | if (!nofork) { |
132 | daemon(0, 0); |
133 | nofork = 1; |
134 | } |
135 | #endif |
136 | |
137 | // This turns us (the process that calls this ioctl) |
138 | // into a dedicated NBD request handler. |
139 | // We block here for a long time. |
140 | // When exactly ioctl returns? On a signal, |
141 | // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d]. |
142 | if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) { |
143 | // Flush queue and exit |
144 | ioctl(nbd, NBD_CLEAR_QUEUE); |
145 | ioctl(nbd, NBD_CLEAR_SOCK); |
146 | break; |
147 | } |
148 | |
149 | close(sock); |
150 | close(nbd); |
151 | } |
152 | |
153 | return 0; |
154 | } |
155 |