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
56 int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
nbdclient_main(int argc,char ** argv)57 int 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_simple_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_simple_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_simple_perror_msg_and_die("BLKROSET");
244 }
245
246 if (timeout) {
247 if (ioctl(nbd, NBD_SET_TIMEOUT, (unsigned long) timeout)) {
248 bb_simple_perror_msg_and_die("NBD_SET_TIMEOUT");
249 }
250 }
251
252 if (ioctl(nbd, NBD_SET_SOCK, sock)) {
253 bb_simple_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 sleep1();
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