1 /* nbd-client.c - network block device client
2 *
3 * Copyright 2010 Rob Landley <rob@landley.net>
4 *
5 * Not in SUSv4.
6
7 // This little dance is because a NEWTOY with - in the name tries to do
8 // things like prototype "nbd-client_main" which isn't a valid symbol. So
9 // we hide the underscore name and OLDTOY the name we want.
10 USE_NBD_CLIENT(NEWTOY(nbd_client, "<3>3ns", 0))
11 USE_NBD_CLIENT(OLDTOY(nbd-client, nbd_client, TOYFLAG_USR|TOYFLAG_BIN))
12
13 config NBD_CLIENT
14 bool "nbd-client"
15 default y
16 help
17 usage: nbd-client [-ns] HOST PORT DEVICE
18
19 -n Do not fork into background
20 -s nbd swap support (lock server into memory)
21 */
22
23 /* TODO:
24 usage: nbd-client [-sSpn] [-b BLKSZ] [-t SECS] [-N name] HOST PORT DEVICE
25
26 -b block size
27 -t timeout in seconds
28 -S sdp
29 -p persist
30 -n nofork
31 -d DEVICE
32 -c DEVICE
33 */
34
35 #define FOR_nbd_client
36 #include "toys.h"
37 #include <linux/nbd.h>
38
nbd_client_main(void)39 void nbd_client_main(void)
40 {
41 int sock = -1, nbd, flags;
42 unsigned long timeout = 0;
43 struct addrinfo *addr, *p;
44 char *host=toys.optargs[0], *port=toys.optargs[1], *device=toys.optargs[2];
45 uint64_t devsize;
46
47 // Repeat until spanked
48
49 nbd = xopen(device, O_RDWR);
50 for (;;) {
51 int temp;
52 struct addrinfo hints;
53
54 // Find and connect to server
55
56 memset(&hints, 0, sizeof(hints));
57 hints.ai_family = PF_UNSPEC;
58 hints.ai_socktype = SOCK_STREAM;
59 if (getaddrinfo(host, port, &hints, &addr)) addr = 0;
60 for (p = addr; p; p = p->ai_next) {
61 sock = socket(p->ai_family, p->ai_socktype, p->ai_protocol);
62 if (-1 != connect(sock, p->ai_addr, p->ai_addrlen)) break;
63 close(sock);
64 }
65 freeaddrinfo(addr);
66
67 if (!p) perror_exit("%s:%s", host, port);
68
69 temp = 1;
70 setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &temp, sizeof(int));
71
72 // Read login data
73
74 xreadall(sock, toybuf, 152);
75 if (memcmp(toybuf, "NBDMAGIC\x00\x00\x42\x02\x81\x86\x12\x53", 16))
76 error_exit("bad login %s:%s", host, port);
77 devsize = SWAP_BE64(*(uint64_t *)(toybuf+16));
78 flags = SWAP_BE32(*(int *)(toybuf+24));
79
80 // Set 4k block size. Everything uses that these days.
81 ioctl(nbd, NBD_SET_BLKSIZE, 4096);
82 ioctl(nbd, NBD_SET_SIZE_BLOCKS, devsize/4096);
83 ioctl(nbd, NBD_CLEAR_SOCK);
84
85 // If the sucker was exported read only, respect that locally.
86 temp = (flags & 2) ? 1 : 0;
87 xioctl(nbd, BLKROSET, &temp);
88
89 if (timeout && ioctl(nbd, NBD_SET_TIMEOUT, timeout)<0) break;
90 if (ioctl(nbd, NBD_SET_SOCK, sock) < 0) break;
91
92 if (toys.optflags & FLAG_s) mlockall(MCL_CURRENT|MCL_FUTURE);
93
94 // Open the device to force reread of the partition table.
95 if ((toys.optflags & FLAG_n) || !xfork()) {
96 char *s = strrchr(device, '/');
97 int i;
98
99 sprintf(toybuf, "/sys/block/%.32s/pid", s ? s+1 : device);
100 // Is it up yet? (Give it 10 seconds.)
101 for (i=0; i<100; i++) {
102 temp = open(toybuf, O_RDONLY);
103 if (temp == -1) msleep(100);
104 else {
105 close(temp);
106 break;
107 }
108 }
109 close(open(device, O_RDONLY));
110 if (!(toys.optflags & FLAG_n)) exit(0);
111 }
112
113 // Daemonize here.
114
115 if (daemon(0,0)) perror_exit("daemonize");
116
117 // Process NBD requests until further notice.
118
119 if (ioctl(nbd, NBD_DO_IT)>=0 || errno==EBADR) break;
120 close(sock);
121 }
122
123 // Flush queue and exit.
124 ioctl(nbd, NBD_CLEAR_QUE);
125 ioctl(nbd, NBD_CLEAR_SOCK);
126 if (CFG_TOYBOX_FREE) close(nbd);
127 }
128