nbd-client.c

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/*
 * Open connection for network block device
 *
 * Copyright 1997,1998 Pavel Machek, distribute under GPL
 *  <pavel@atrey.karlin.mff.cuni.cz>
 *
 * Version 1.0 - 64bit issues should be fixed, now
 * Version 1.1 - added bs (blocksize) option (Alexey Guzeev, aga@permonline.ru)
 * Version 1.2 - I added new option '-d' to send the disconnect request
 * Version 2.0 - Version synchronised with server
 * Version 2.1 - Check for disconnection before INIT_PASSWD is received
 *      to make errormsg a bit more helpful in case the server can't
 *      open the exported file.
 */

#include "config.h"
#include "lfs.h"

#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <netinet/tcp.h>
#include <netinet/in.h>         /* sockaddr_in, htons, in_addr */
#include <netdb.h>              /* hostent, gethostby*, getservby* */
#include <stdio.h>
#include <fcntl.h>
#include <syslog.h>
#include <stdlib.h>

#ifndef __GNUC__
#error I need GCC to work
#endif

#include <linux/ioctl.h>
#define MY_NAME "nbd_client"
#include "cliserv.h"

int opennet(char *name, int port) {
        int sock;
        struct sockaddr_in xaddrin;
        int xaddrinlen = sizeof(xaddrin);
        struct hostent *hostn;

        hostn = gethostbyname(name);
        if (!hostn)
                err("Gethostname failed: %h\n");

        if ((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
                err("Socket failed: %m");

        xaddrin.sin_family = AF_INET;
        xaddrin.sin_port = htons(port);
        xaddrin.sin_addr.s_addr = *((int *) hostn->h_addr);
        if ((connect(sock, (struct sockaddr *) &xaddrin, xaddrinlen) < 0))
                err("Connect: %m");

        setmysockopt(sock);
        return sock;
}

u64 negotiate(int sock, int blocksize) {
        u64 magic, size64;
        char buf[256] = "\0\0\0\0\0\0\0\0\0";

        printf("Negotiation: ");
        if (read(sock, buf, 8) < 0)
                err("Failed/1: %m");
        if (strlen(buf)==0)
                err("Server closed connection");
        if (strcmp(buf, INIT_PASSWD))
                err("INIT_PASSWD bad");
        printf(".");
        if (read(sock, &magic, sizeof(magic)) < 0)
                err("Failed/2: %m");
        magic = ntohll(magic);
        if (magic != cliserv_magic)
                err("Not enough cliserv_magic");
        printf(".");

        if (read(sock, &size64, sizeof(size64)) < 0)
                err("Failed/3: %m\n");
        size64 = ntohll(size64);

#ifdef NBD_SET_SIZE_BLOCKS
        if ((size64>>10) > (~0UL >> 1)) {
                printf("size = %luMB", (unsigned long)(size64>>20));
                err("Exported device is too big for me. Get 64-bit machine :-(\n");
        } else
                printf("size = %luKB", (unsigned long)(size64>>10));
#else
        if (size64 > (~0UL >> 1)) {
                printf("size = %luKB", (unsigned long)(size64>>10));
                err("Exported device is too big. Get 64-bit machine or newer kernel :-(\n");
        } else
                printf("size = %lu", (unsigned long)(size64));
#endif

        if (read(sock, &buf, 128) < 0)
                err("Failed/4: %m\n");
        printf("\n");

        return size64;
}

void setsizes(int nbd, u64 size64, int blocksize) {
        unsigned long size;

#ifdef NBD_SET_SIZE_BLOCKS
        if (size64/blocksize > (~0UL >> 1))
                err("Device too large.\n");
        else {
                int er;
                if (ioctl(nbd, NBD_SET_BLKSIZE, (unsigned long)blocksize) < 0)
                        err("Ioctl/1.1a failed: %m\n");
                size = (unsigned long)(size64/blocksize);
                if ((er = ioctl(nbd, NBD_SET_SIZE_BLOCKS, size)) < 0)
                        err("Ioctl/1.1b failed: %m\n");
                fprintf(stderr, "bs=%d, sz=%lu\n", blocksize, size);
        }
#else
        if (size64 > (~0UL >> 1)) {
                err("Device too large.\n");
        } else {
                size = (unsigned long)size64;
                if (ioctl(nbd, NBD_SET_SIZE, size) < 0)
                        err("Ioctl NBD_SET_SIZE failed: %m\n");
        }
#endif

        ioctl(nbd, NBD_CLEAR_SOCK);
}

void finish_sock(int sock, int nbd, int swap) {
        if (ioctl(nbd, NBD_SET_SOCK, sock) < 0)
                err("Ioctl NBD_SET_SOCK failed: %m\n");

#ifndef SO_SWAPPING
        if (swap)
                err("You have to compile me on machine with swapping patch enabled in order to use it later.");
#else
        if (swap)
                if (setsockopt(sock, SOL_SOCKET, SO_SWAPPING, &one, sizeof(int)) < 0)
                        err("Could not enable swapping: %m");
#endif
}

int main(int argc, char *argv[]) {
        int port, sock, nbd;
        int blocksize=1024;
        char *hostname, *nbddev;
        int swap=0;
        int cont=0;
        u64 size64;

        logging();

        if (argc < 3) {
        errmsg:
                fprintf(stderr, "nbd-client version %s\n", PACKAGE_VERSION);
                fprintf(stderr, "Usage: nbd-client [bs=blocksize] host port nbd_device [-swap] [-persist]\n");
                fprintf(stderr, "Or   : nbd-client -d nbd_device\n");
                fprintf(stderr, "Default value for blocksize is 1024 (recommended for ethernet)\n");
                fprintf(stderr, "Allowed values for blocksize are 512,1024,2048,4096\n"); /* will be checked in kernel :) */
                fprintf(stderr, "Note, that kernel 2.4.2 and older ones do not work correctly with\n");
                fprintf(stderr, "blocksizes other than 1024 without patches\n");
                return 1;
        }

        ++argv; --argc; /* skip programname */
        
        if (strcmp(argv[0], "-d")==0) {
                nbd = open(argv[1], O_RDWR);
                if (nbd < 0)
                        err("Can not open NBD: %m");
                printf("Disconnecting: que, ");
                if (ioctl(nbd, NBD_CLEAR_QUE)< 0)
                        err("Ioctl failed: %m\n");
                printf("disconnect, ");
#ifdef NBD_DISCONNECT
                if (ioctl(nbd, NBD_DISCONNECT)<0)
                        err("Ioctl failed: %m\n");
                printf("sock, ");
#else
                fprintf(stderr, "Can't disconnect: I was not compiled with disconnect support!\n" );
                exit(1);
#endif
                if (ioctl(nbd, NBD_CLEAR_SOCK)<0)
                        err("Ioctl failed: %m\n");
                printf("done\n");
                return 0;
        }
        
        if (strncmp(argv[0], "bs=", 3)==0) {
                blocksize=atoi(argv[0]+3);
                ++argv; --argc; /* skip blocksize */
        }

        if (argc==0) goto errmsg;
        hostname=argv[0];
        ++argv; --argc; /* skip hostname */

        if (argc==0) goto errmsg;
        port = atoi(argv[0]);
        ++argv; --argc; /* skip port */

        if (argc==0) goto errmsg;
        sock = opennet(hostname, port);
        nbddev = argv[0];
        nbd = open(nbddev, O_RDWR);
        if (nbd < 0)
          err("Can not open NBD: %m");
        ++argv; --argc; /* skip device */

        if (argc>2) goto errmsg;
        if (argc!=0) {
                if(strncmp(argv[0], "-swap", 5)==0) {
                        swap=1;
                        ++argv;--argc;
                }
        }
        if (argc!=0) {
                if(strncmp(argv[0], "-persist", 8)==0) {
                        cont=1;
                        ++argv;--argc;
                }
        }
        argv=NULL; argc=0; /* don't use it later suddenly */

        size64 = negotiate(sock, blocksize);
        setsizes(nbd, size64, blocksize);
        finish_sock(sock, nbd, swap);

        /* Go daemon */
        
        chdir("/");
#ifndef NOFORK
        if (fork())
                exit(0);
#endif

        do {
                if (ioctl(nbd, NBD_DO_IT) < 0) {
                        fprintf(stderr, "Kernel call returned: %m");
                        if(errno==EBADR) {
                                /* The user probably did 'nbd-client -d' on us.
                                 * quit */
                                cont=0;
                        } else {
                                if(cont) {
                                        fprintf(stderr, " Reconnecting\n");
                                        close(sock); close(nbd);
                                        sock = opennet(hostname, port);
                                        nbd = open(nbddev, O_RDWR);
                                        if(size64!=negotiate(sock,blocksize)) {
                                                err("Size of the device changed. Bye");
                                        }
                                        setsizes(nbd, size64, blocksize);
                                        finish_sock(sock,nbd,swap);
                                }
                        }
                } else {
                        /* We're on 2.4. It's not clearly defined what exactly
                         * happened at this point. Probably best to quit, now
                         */
                        fprintf(stderr, "Kernel call returned.");
                        cont=0;
                }
        } while(cont);
        printf("Closing: que, ");
        ioctl(nbd, NBD_CLEAR_QUE);
        printf("sock, ");
        ioctl(nbd, NBD_CLEAR_SOCK);
        printf("done\n");
        return 0;
}

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