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 "block_int.h" 32 #include "module.h" 33 #include "qemu_socket.h" 34 35 #include <sys/types.h> 36 #include <unistd.h> 37 38 #define EN_OPTSTR ":exportname=" 39 40 /* #define DEBUG_NBD */ 41 42 #if defined(DEBUG_NBD) 43 #define logout(fmt, ...) \ 44 fprintf(stderr, "nbd\t%-24s" fmt, __func__, ##__VA_ARGS__) 45 #else 46 #define logout(fmt, ...) ((void)0) 47 #endif 48 49 typedef struct BDRVNBDState { 50 int sock; 51 uint32_t nbdflags; 52 off_t size; 53 size_t blocksize; 54 char *export_name; /* An NBD server may export several devices */ 55 56 /* If it begins with '/', this is a UNIX domain socket. Otherwise, 57 * it's a string of the form <hostname|ip4|\[ip6\]>:port 58 */ 59 char *host_spec; 60 } BDRVNBDState; 61 62 static int nbd_config(BDRVNBDState *s, const char *filename, int flags) 63 { 64 char *file; 65 char *export_name; 66 const char *host_spec; 67 const char *unixpath; 68 int err = -EINVAL; 69 70 file = g_strdup(filename); 71 72 export_name = strstr(file, EN_OPTSTR); 73 if (export_name) { 74 if (export_name[strlen(EN_OPTSTR)] == 0) { 75 goto out; 76 } 77 export_name[0] = 0; /* truncate 'file' */ 78 export_name += strlen(EN_OPTSTR); 79 s->export_name = g_strdup(export_name); 80 } 81 82 /* extract the host_spec - fail if it's not nbd:... */ 83 if (!strstart(file, "nbd:", &host_spec)) { 84 goto out; 85 } 86 87 /* are we a UNIX or TCP socket? */ 88 if (strstart(host_spec, "unix:", &unixpath)) { 89 if (unixpath[0] != '/') { /* We demand an absolute path*/ 90 goto out; 91 } 92 s->host_spec = g_strdup(unixpath); 93 } else { 94 s->host_spec = g_strdup(host_spec); 95 } 96 97 err = 0; 98 99 out: 100 g_free(file); 101 if (err != 0) { 102 g_free(s->export_name); 103 g_free(s->host_spec); 104 } 105 return err; 106 } 107 108 static int nbd_establish_connection(BlockDriverState *bs) 109 { 110 BDRVNBDState *s = bs->opaque; 111 int sock; 112 int ret; 113 off_t size; 114 size_t blocksize; 115 116 if (s->host_spec[0] == '/') { 117 sock = unix_socket_outgoing(s->host_spec); 118 } else { 119 sock = tcp_socket_outgoing_spec(s->host_spec); 120 } 121 122 /* Failed to establish connection */ 123 if (sock == -1) { 124 logout("Failed to establish connection to NBD server\n"); 125 return -errno; 126 } 127 128 /* NBD handshake */ 129 ret = nbd_receive_negotiate(sock, s->export_name, &s->nbdflags, &size, 130 &blocksize); 131 if (ret == -1) { 132 logout("Failed to negotiate with the NBD server\n"); 133 closesocket(sock); 134 return -errno; 135 } 136 137 /* Now that we're connected, set the socket to be non-blocking */ 138 socket_set_nonblock(sock); 139 140 s->sock = sock; 141 s->size = size; 142 s->blocksize = blocksize; 143 144 logout("Established connection with NBD server\n"); 145 return 0; 146 } 147 148 static void nbd_teardown_connection(BlockDriverState *bs) 149 { 150 BDRVNBDState *s = bs->opaque; 151 struct nbd_request request; 152 153 request.type = NBD_CMD_DISC; 154 request.handle = (uint64_t)(intptr_t)bs; 155 request.from = 0; 156 request.len = 0; 157 nbd_send_request(s->sock, &request); 158 159 closesocket(s->sock); 160 } 161 162 static int nbd_open(BlockDriverState *bs, const char* filename, int flags) 163 { 164 BDRVNBDState *s = bs->opaque; 165 int result; 166 167 /* Pop the config into our state object. Exit if invalid. */ 168 result = nbd_config(s, filename, flags); 169 if (result != 0) { 170 return result; 171 } 172 173 /* establish TCP connection, return error if it fails 174 * TODO: Configurable retry-until-timeout behaviour. 175 */ 176 result = nbd_establish_connection(bs); 177 178 return result; 179 } 180 181 static int nbd_read(BlockDriverState *bs, int64_t sector_num, 182 uint8_t *buf, int nb_sectors) 183 { 184 BDRVNBDState *s = bs->opaque; 185 struct nbd_request request; 186 struct nbd_reply reply; 187 188 request.type = NBD_CMD_READ; 189 request.handle = (uint64_t)(intptr_t)bs; 190 request.from = sector_num * 512;; 191 request.len = nb_sectors * 512; 192 193 if (nbd_send_request(s->sock, &request) == -1) 194 return -errno; 195 196 if (nbd_receive_reply(s->sock, &reply) == -1) 197 return -errno; 198 199 if (reply.error !=0) 200 return -reply.error; 201 202 if (reply.handle != request.handle) 203 return -EIO; 204 205 if (nbd_wr_sync(s->sock, buf, request.len, 1) != request.len) 206 return -EIO; 207 208 return 0; 209 } 210 211 static int nbd_write(BlockDriverState *bs, int64_t sector_num, 212 const uint8_t *buf, int nb_sectors) 213 { 214 BDRVNBDState *s = bs->opaque; 215 struct nbd_request request; 216 struct nbd_reply reply; 217 218 request.type = NBD_CMD_WRITE; 219 request.handle = (uint64_t)(intptr_t)bs; 220 request.from = sector_num * 512;; 221 request.len = nb_sectors * 512; 222 223 if (nbd_send_request(s->sock, &request) == -1) 224 return -errno; 225 226 if (nbd_wr_sync(s->sock, (uint8_t*)buf, request.len, 0) != request.len) 227 return -EIO; 228 229 if (nbd_receive_reply(s->sock, &reply) == -1) 230 return -errno; 231 232 if (reply.error !=0) 233 return -reply.error; 234 235 if (reply.handle != request.handle) 236 return -EIO; 237 238 return 0; 239 } 240 241 static void nbd_close(BlockDriverState *bs) 242 { 243 BDRVNBDState *s = bs->opaque; 244 g_free(s->export_name); 245 g_free(s->host_spec); 246 247 nbd_teardown_connection(bs); 248 } 249 250 static int64_t nbd_getlength(BlockDriverState *bs) 251 { 252 BDRVNBDState *s = bs->opaque; 253 254 return s->size; 255 } 256 257 static BlockDriver bdrv_nbd = { 258 .format_name = "nbd", 259 .instance_size = sizeof(BDRVNBDState), 260 .bdrv_file_open = nbd_open, 261 .bdrv_read = nbd_read, 262 .bdrv_write = nbd_write, 263 .bdrv_close = nbd_close, 264 .bdrv_getlength = nbd_getlength, 265 .protocol_name = "nbd", 266 }; 267 268 static void bdrv_nbd_init(void) 269 { 270 bdrv_register(&bdrv_nbd); 271 } 272 273 block_init(bdrv_nbd_init); 274