diff options
| -rw-r--r-- | networking/nbd-client.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/networking/nbd-client.c b/networking/nbd-client.c new file mode 100644 index 0000000..5ac190c --- /dev/null +++ b/networking/nbd-client.c @@ -0,0 +1,153 @@ +/* + * Copyright 2010 Rob Landley <rob@landley.net> + * + * Licensed under GPLv2, see file LICENSE in this source tree. + */ +#include "libbb.h" +#include <netinet/tcp.h> +#include <linux/fs.h> + +//applet:IF_NBDCLIENT(APPLET_ODDNAME(nbd-client, nbdclient, _BB_DIR_USR_SBIN, _BB_SUID_DROP, nbdclient)) + +//kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o + +//config:config NBDCLIENT +//config: bool "nbd-client" +//config: default y +//config: help +//config: Network block device client + +#define NBD_SET_SOCK _IO(0xab, 0) +#define NBD_SET_BLKSIZE _IO(0xab, 1) +#define NBD_SET_SIZE _IO(0xab, 2) +#define NBD_DO_IT _IO(0xab, 3) +#define NBD_CLEAR_SOCK _IO(0xab, 4) +#define NBD_CLEAR_QUEUE _IO(0xab, 5) +#define NBD_PRINT_DEBUG _IO(0xab, 6) +#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7) +#define NBD_DISCONNECT _IO(0xab, 8) +#define NBD_SET_TIMEOUT _IO(0xab, 9) + +//usage:#define nbdclient_trivial_usage +//usage: "HOST PORT BLOCKDEV" +//usage:#define nbdclient_full_usage "\n\n" +//usage: "Connect to HOST and provide a network block device on BLOCKDEV" + +//TODO: more compat with nbd-client version 2.9.13 - +//Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist] [-nofork] +//Or : nbd-client -d nbd_device +//Or : nbd-client -c nbd_device +//Default value for blocksize is 1024 (recommended for ethernet) +//Allowed values for blocksize are 512,1024,2048,4096 +//Note, that kernel 2.4.2 and older ones do not work correctly with +//blocksizes other than 1024 without patches + +int nbdclient_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; +int nbdclient_main(int argc, char **argv) +{ + unsigned long timeout = 0; + int nofork = 0; + char *host, *port, *device; + struct nbd_header_t { + uint64_t magic1; // "NBDMAGIC" + uint64_t magic2; // 0x420281861253 big endian + uint64_t devsize; + uint32_t flags; + char data[124]; + } nbd_header; + struct bug_check { + char c[offsetof(struct nbd_header_t, data) == 8+8+8+4 ? 1 : -1]; + }; + + // Parse command line stuff (just a stub now) + if (argc != 4) + bb_show_usage(); + +#if !BB_MMU + bb_daemonize_or_rexec(DAEMON_CLOSE_EXTRA_FDS, argv); +#endif + + host = argv[1]; + port = argv[2]; + device = argv[3]; + + // Repeat until spanked (-persist behavior) + for (;;) { + int sock, nbd; + int ro; + + // Make sure the /dev/nbd exists + nbd = xopen(device, O_RDWR); + + // Find and connect to server + sock = create_and_connect_stream_or_die(host, xatou16(port)); + setsockopt(sock, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1)); + + // Log on to the server + xread(sock, &nbd_header, 8+8+8+4 + 124); + if (memcmp(&nbd_header.magic1, "NBDMAGIC""\x00\x00\x42\x02\x81\x86\x12\x53", 16) != 0) + bb_error_msg_and_die("login failed"); + + // Set 4k block size. Everything uses that these days + ioctl(nbd, NBD_SET_BLKSIZE, 4096); + ioctl(nbd, NBD_SET_SIZE_BLOCKS, SWAP_BE64(nbd_header.devsize) / 4096); + ioctl(nbd, NBD_CLEAR_SOCK); + + // If the sucker was exported read only, respect that locally + ro = (nbd_header.flags & SWAP_BE32(2)) / SWAP_BE32(2); + if (ioctl(nbd, BLKROSET, &ro) < 0) + bb_perror_msg_and_die("BLKROSET"); + + if (timeout) + if (ioctl(nbd, NBD_SET_TIMEOUT, timeout)) + bb_perror_msg_and_die("NBD_SET_TIMEOUT"); + if (ioctl(nbd, NBD_SET_SOCK, sock)) + bb_perror_msg_and_die("NBD_SET_SOCK"); + + // if (swap) mlockall(MCL_CURRENT|MCL_FUTURE); + +#if BB_MMU + // Open the device to force reread of the partition table. + // Need to do it in a separate process, since open(device) + // needs some other process to sit in ioctl(nbd, NBD_DO_IT). + if (fork() == 0) { + char *s = strrchr(device, '/'); + sprintf(nbd_header.data, "/sys/block/%.32s/pid", s ? s + 1 : device); + // Is it up yet? + for (;;) { + int fd = open(nbd_header.data, O_RDONLY); + if (fd >= 0) { + //close(fd); + break; + } + sleep(1); + } + open(device, O_RDONLY); + return 0; + } + + // Daemonize here + if (!nofork) { + daemon(0, 0); + nofork = 1; + } +#endif + + // This turns us (the process that calls this ioctl) + // into a dedicated NBD request handler. + // We block here for a long time. + // When exactly ioctl returns? On a signal, + // or if someone does ioctl(NBD_DISCONNECT) [nbd-client -d]. + if (ioctl(nbd, NBD_DO_IT) >= 0 || errno == EBADR) { + // Flush queue and exit + ioctl(nbd, NBD_CLEAR_QUEUE); + ioctl(nbd, NBD_CLEAR_SOCK); + break; + } + + close(sock); + close(nbd); + } + + return 0; +} |