block/nbd.c

   1 /*
   2  * QEMU Block driver for  NBD
   3  *
   4  * Copyright (C) 2008 Bull S.A.S.
   5  *     Author: Laurent Vivier <Laurent.Vivier@bull.net>
   6  *
   7  * Some parts:
   8  *    Copyright (C) 2007 Anthony Liguori <anthony@codemonkey.ws>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  26  * THE SOFTWARE.
  27  */
  28
  29 #include "qemu-common.h"
  30 #include "nbd.h"
  31 #include "module.h"
  32 #include "qemu_socket.h"
  33
  34 #include <sys/types.h>
  35 #include <unistd.h>
  36
  37 #define EN_OPTSTR ":exportname="
  38
  39 /* #define DEBUG_NBD */
  40
  41 #if defined(DEBUG_NBD)
  42 #define logout(fmt, ...) \
  43                 fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__)
  44 #else
  45 #define logout(fmt, ...) ((void)0)
  46 #endif
  47
  48 typedef struct BDRVNBDState {
  49     int sock;
  50     off_t size;
  51     size_t blocksize;
  52     char *export_name; /* An NBD server may export several devices */
  53
  54     /* If it begins with  '/', this is a UNIX domain socket. Otherwise,
  55      * it's a string of the form <hostname|ip4|\[ip6\]>:port
  56      */
  57     char *host_spec;
  58 } BDRVNBDState;
  59
  60 static int nbd_config(BDRVNBDState *s, const char *filename, int flags)
  61 {
  62     char *file;
  63     char *export_name;
  64     const char *host_spec;
  65     const char *unixpath;
  66     int err = -EINVAL;
  67
  68     file = qemu_strdup(filename);
  69
  70     export_name = strstr(file, EN_OPTSTR);
  71     if (export_name) {
  72         if (export_name[strlen(EN_OPTSTR)] == 0) {
  73             goto out;
  74         }
  75         export_name[0] = 0; /* truncate 'file' */
  76         export_name += strlen(EN_OPTSTR);
  77         s->export_name = qemu_strdup(export_name);
  78     }
  79
  80     /* extract the host_spec - fail if it's not nbd:... */
  81     if (!strstart(file, "nbd:", &host_spec)) {
  82         goto out;
  83     }
  84
  85     /* are we a UNIX or TCP socket? */
  86     if (strstart(host_spec, "unix:", &unixpath)) {
  87         if (unixpath[0] != '/') { /* We demand  an absolute path*/
  88             goto out;
  89         }
  90         s->host_spec = qemu_strdup(unixpath);
  91     } else {
  92         s->host_spec = qemu_strdup(host_spec);
  93     }
  94
  95     err = 0;
  96
  97 out:
  98     qemu_free(file);
  99     if (err != 0) {
 100         qemu_free(s->export_name);
 101         qemu_free(s->host_spec);
 102     }
 103     return err;
 104 }
 105
 106 static int nbd_establish_connection(BlockDriverState *bs)
 107 {
 108     BDRVNBDState *s = bs->opaque;
 109     int sock;
 110     int ret;
 111     off_t size;
 112     size_t blocksize;
 113     uint32_t nbdflags;
 114
 115     if (s->host_spec[0] == '/') {
 116         sock = unix_socket_outgoing(s->host_spec);
 117     } else {
 118         sock = tcp_socket_outgoing_spec(s->host_spec);
 119     }
 120
 121     /* Failed to establish connection */
 122     if (sock == -1) {
 123         logout("Failed to establish connection to NBD server\n");
 124         return -errno;
 125     }
 126
 127     /* NBD handshake */
 128     ret = nbd_receive_negotiate(sock, s->export_name, &nbdflags, &size,
 129                                 &blocksize);
 130     if (ret == -1) {
 131         logout("Failed to negotiate with the NBD server\n");
 132         closesocket(sock);
 133         return -errno;
 134     }
 135
 136     /* Now that we're connected, set the socket to be non-blocking */
 137     socket_set_nonblock(sock);
 138
 139     s->sock = sock;
 140     s->size = size;
 141     s->blocksize = blocksize;
 142
 143     logout("Established connection with NBD server\n");
 144     return 0;
 145 }
 146
 147 static void nbd_teardown_connection(BlockDriverState *bs)
 148 {
 149     BDRVNBDState *s = bs->opaque;
 150     struct nbd_request request;
 151
 152     request.type = NBD_CMD_DISC;
 153     request.handle = (uint64_t)(intptr_t)bs;
 154     request.from = 0;
 155     request.len = 0;
 156     nbd_send_request(s->sock, &request);
 157
 158     closesocket(s->sock);
 159 }
 160
 161 static int nbd_open(BlockDriverState *bs, const char* filename, int flags)
 162 {
 163     BDRVNBDState *s = bs->opaque;
 164     int result;
 165
 166     /* Pop the config into our state object. Exit if invalid. */
 167     result = nbd_config(s, filename, flags);
 168     if (result != 0) {
 169         return result;
 170     }
 171
 172     /* establish TCP connection, return error if it fails
 173      * TODO: Configurable retry-until-timeout behaviour.
 174      */
 175     result = nbd_establish_connection(bs);
 176
 177     return result;
 178 }
 179
 180 static int nbd_read(BlockDriverState *bs, int64_t sector_num,
 181                     uint8_t *buf, int nb_sectors)
 182 {
 183     BDRVNBDState *s = bs->opaque;
 184     struct nbd_request request;
 185     struct nbd_reply reply;
 186
 187     request.type = NBD_CMD_READ;
 188     request.handle = (uint64_t)(intptr_t)bs;
 189     request.from = sector_num * 512;;
 190     request.len = nb_sectors * 512;
 191
 192     if (nbd_send_request(s->sock, &request) == -1)
 193         return -errno;
 194
 195     if (nbd_receive_reply(s->sock, &reply) == -1)
 196         return -errno;
 197
 198     if (reply.error !=0)
 199         return -reply.error;
 200
 201     if (reply.handle != request.handle)
 202         return -EIO;
 203
 204     if (nbd_wr_sync(s->sock, buf, request.len, 1) != request.len)
 205         return -EIO;
 206
 207     return 0;
 208 }
 209
 210 static int nbd_write(BlockDriverState *bs, int64_t sector_num,
 211                      const uint8_t *buf, int nb_sectors)
 212 {
 213     BDRVNBDState *s = bs->opaque;
 214     struct nbd_request request;
 215     struct nbd_reply reply;
 216
 217     request.type = NBD_CMD_WRITE;
 218     request.handle = (uint64_t)(intptr_t)bs;
 219     request.from = sector_num * 512;;
 220     request.len = nb_sectors * 512;
 221
 222     if (nbd_send_request(s->sock, &request) == -1)
 223         return -errno;
 224
 225     if (nbd_wr_sync(s->sock, (uint8_t*)buf, request.len, 0) != request.len)
 226         return -EIO;
 227
 228     if (nbd_receive_reply(s->sock, &reply) == -1)
 229         return -errno;
 230
 231     if (reply.error !=0)
 232         return -reply.error;
 233
 234     if (reply.handle != request.handle)
 235         return -EIO;
 236
 237     return 0;
 238 }
 239
 240 static void nbd_close(BlockDriverState *bs)
 241 {
 242     nbd_teardown_connection(bs);
 243 }
 244
 245 static int64_t nbd_getlength(BlockDriverState *bs)
 246 {
 247     BDRVNBDState *s = bs->opaque;
 248
 249     return s->size;
 250 }
 251
 252 static BlockDriver bdrv_nbd = {
 253     .format_name        = "nbd",
 254     .instance_size      = sizeof(BDRVNBDState),
 255     .bdrv_file_open     = nbd_open,
 256     .bdrv_read          = nbd_read,
 257     .bdrv_write         = nbd_write,
 258     .bdrv_close         = nbd_close,
 259     .bdrv_getlength     = nbd_getlength,
 260     .protocol_name      = "nbd",
 261 };
 262
 263 static void bdrv_nbd_init(void)
 264 {
 265     bdrv_register(&bdrv_nbd);
 266 }
 267
 268 block_init(bdrv_nbd_init);