blob: cadda5261dc2aca9654fce83c3c841f2d4a1842a
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 | struct bug_check { |
61 | char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1]; |
62 | }; |
63 | |
64 | // Parse command line stuff (just a stub now) |
65 | if (argc != 4) |
66 | bb_show_usage(); |
67 | |
68 | #if !BB_MMU |
69 | bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv); |
70 | #endif |
71 | |
72 | host = argv[1]; |
73 | port = argv[2]; |
74 | device = argv[3]; |
75 | |
76 | // Repeat until spanked (-persist behavior) |
77 | for (;;) { |
78 | int sock, nbd; |
79 | int ro; |
80 | |
81 | // Make sure the /dev/nbd exists |
82 | nbd = xopen(device, O_RDWR); |
83 | |
84 | // Find and connect to server |
85 | sock = create_and_connect_stream_or_die(host, xatou16(port)); |
86 | setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1)); |
87 | |
88 | // Log on to the server |
89 | xread(sock, &nbd_header, 8+8+8+4 + 124); |
90 | if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0) |
91 | bb_error_msg_and_die("login failed"); |
92 | |
93 | // Set 4k block size. Everything uses that these days |
94 | ioctl(nbd, NBD_SET_BLKSIZE, 4096); |
95 | ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096); |
96 | ioctl(nbd, NBD_CLEAR_SOCK); |
97 | |
98 | // If the sucker was exported read only, respect that locally |
99 | ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2); |
100 | if (ioctl(nbd, BLKROSET, &ro) < 0) |
101 | bb_perror_msg_and_die("BLKROSET"); |
102 | |
103 | if (timeout) |
104 | if (ioctl(nbd, NBD_SET_TIMEOUT, timeout)) |
105 | bb_perror_msg_and_die("NBD_SET_TIMEOUT"); |
106 | if (ioctl(nbd, NBD_SET_SOCK, sock)) |
107 | bb_perror_msg_and_die("NBD_SET_SOCK"); |
108 | |
109 | // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE); |
110 | |
111 | #if BB_MMU |
112 | // Open the device to force reread of the partition table. |
113 | // Need to do it in a separate process, since open(device) |
114 | // needs some other process to sit in ioctl(nbd, NBD_DO_IT). |
115 | if (fork() == 0) { |
116 | char *s = strrchr(device, '/'); |
117 | sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device); |
118 | // Is it up yet? |
119 | for (;;) { |
120 | int fd = open(nbd_header.data, O_RDONLY); |
121 | if (fd >= 0) { |
122 | //close(fd); |
123 | break; |
124 | } |
125 | sleep(1); |
126 | } |
127 | open(device, O_RDONLY); |
128 | return 0; |
129 | } |
130 | |
131 | // Daemonize here |
132 | if (!nofork) { |
133 | daemon(0, 0); |
134 | nofork = 1; |
135 | } |
136 | #endif |
137 | |
138 | // This turns us (the process that calls this ioctl) |
139 | // into a dedicated NBD request handler. |
140 | // We block here for a long time. |
141 | // When exactly ioctl returns? On a signal, |
142 | // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d]. |
143 | if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) { |
144 | // Flush queue and exit |
145 | ioctl(nbd, NBD_CLEAR_QUEUE); |
146 | ioctl(nbd, NBD_CLEAR_SOCK); |
147 | break; |
148 | } |
149 | |
150 | close(sock); |
151 | close(nbd); |
152 | } |
153 | |
154 | return 0; |
155 | } |
156 |