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nbd-client.c

/*
 * 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>
#include <sys/mount.h>
#include <errno.h>

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

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

int check_conn(char* devname, int do_print) {
      char buf[256];
      int fd;
      int len;
      if(!strncmp(devname, "/dev/", 5)) {
            devname+=5;
      }
      snprintf(buf, 256, "/sys/block/%s/pid", devname);
      if((fd=open(buf, O_RDONLY))<0) {
            if(errno==ENOENT) {
                  return 1;
            } else {
                  return 2;
            }
      }
      len=read(fd, buf, 256);
      buf[len-1]='\0';
      if(do_print) printf("%s\n", buf);
      return 0;
}

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

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

      af = AF_INET;
      if(sdp) {
#ifdef WITH_SDP
            af = AF_INET_SDP;
#else
            err("Can't do SDP: I was not compiled with SDP support!");
#endif
      }
      if ((sock = socket(af, SOCK_STREAM, IPPROTO_TCP)) < 0)
            err("Socket failed: %m");

      xaddrin.sin_family = af;
      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;
}

void negotiate(int sock, u64 *rsize64, u32 *flags) {
      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, flags, sizeof(*flags)) < 0)
            err("Failed/4: %m\n");
      *flags = ntohl(*flags);

      if (read(sock, &buf, 124) < 0)
            err("Failed/5: %m\n");
      printf("\n");

      *rsize64 = size64;
}

void setsizes(int nbd, u64 size64, int blocksize, u32 flags) {
      unsigned long size;
      int read_only = (flags & NBD_FLAG_READ_ONLY) ? 1 : 0;

#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);

      if (ioctl(nbd, BLKROSET, (unsigned long) &read_only) < 0)
            err("Unable to set read-only attribute for device");
}

void set_timeout(int nbd, int timeout) {
#ifdef NBD_SET_TIMEOUT
      if (timeout) {
            if (ioctl(nbd, NBD_SET_TIMEOUT, (unsigned long)timeout) < 0)
                  err("Ioctl NBD_SET_TIMEOUT failed: %m\n");
            fprintf(stderr, "timeout=%d\n", timeout);
      }
#endif
}

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;
      int timeout=0;
      int sdp=0;
      u64 size64;
      u32 flags;

      logging();

      if (argc < 3) {
      errmsg:
            fprintf(stderr, "nbd-client version %s\n", PACKAGE_VERSION);
            fprintf(stderr, "Usage: nbd-client [bs=blocksize] [timeout=sec] host port nbd_device [-swap] [-persist]\n");
            fprintf(stderr, "Or   : nbd-client -d nbd_device\n");
            fprintf(stderr, "Or   : nbd-client -c 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(strcmp(argv[0], "-c")==0) {
            return check_conn(argv[1], 1);
      }
      
      if (strncmp(argv[0], "bs=", 3)==0) {
            blocksize=atoi(argv[0]+3);
            ++argv; --argc; /* skip blocksize */
      }

      if (strncmp(argv[0], "timeout=", 8)==0) {
            timeout=atoi(argv[0]+8);
            ++argv; --argc; /* skip timeout */
      }
      
      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;
      nbddev = argv[0];
      nbd = open(nbddev, O_RDWR);
      if (nbd < 0)
        err("Can not open NBD: %m");
      ++argv; --argc; /* skip device */

      if (argc>3) goto errmsg;
      if (argc) {
            if(strncmp(argv[0], "-swap", 5)==0) {
                  swap=1;
                  ++argv;--argc;
            }
      }
      if (argc) {
            if(strncmp(argv[0], "-persist", 8)==0) {
                  cont=1;
                  ++argv;--argc;
            }
      }
      if (argc) {
            if(strncmp(argv[0], "-sdp", 4)==0) {
                  sdp=1;
                  ++argv;--argc;
            }
      }
      if(argc) goto errmsg;
      sock = opennet(hostname, port, sdp);
      argv=NULL; argc=0; /* don't use it later suddenly */

      negotiate(sock, &size64, &flags);
      setsizes(nbd, size64, blocksize, flags);
      set_timeout(nbd, timeout);
      finish_sock(sock, nbd, swap);

      /* Go daemon */
      
      chdir("/");
      do {
#ifndef NOFORK
            if (fork()) {
                  while(check_conn(nbddev, 0)) {
                        sleep(1);
                  }
                  open(nbddev, O_RDONLY);
                  exit(0);
            }
#endif

            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) {
                              u64 new_size;
                              u32 new_flags;

                              fprintf(stderr, " Reconnecting\n");
                              close(sock); close(nbd);
                              sock = opennet(hostname, port, sdp);
                              nbd = open(nbddev, O_RDWR);
                              negotiate(sock, &new_size, &new_flags);
                              if (size64 != new_size) {
                                    err("Size of the device changed. Bye");
                              }
                              setsizes(nbd, size64, blocksize,
                                                new_flags);

                              set_timeout(nbd, timeout);
                              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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