/* * Copyright 2010 Rob Landley <rob@landley.net> * * Licensed under GPLv2, see file LICENSE in this source tree. */ //config:config NBDCLIENT //config: bool "nbd-client (4.6 kb)" //config: default y //config: help //config: Network block device client //applet:IF_NBDCLIENT(APPLET_NOEXEC(nbd-client, nbdclient, BB_DIR_USR_SBIN, BB_SUID_DROP, nbdclient)) //kbuild:lib-$(CONFIG_NBDCLIENT) += nbd-client.o #include "libbb.h" #include <netinet/tcp.h> #include <linux/fs.h> #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 UNUSED_PARAM, char **argv) { unsigned long timeout = 0; #if BB_MMU int nofork = 0; #endif 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; BUILD_BUG_ON(offsetof(struct nbd_header_t, data) != 8+8+8+4); // Parse command line stuff (just a stub now) if (!argv[1] || !argv[2] || !argv[3] || argv[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_1(sock, IPPROTO_TCP, TCP_NODELAY); // 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; }