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 BDRVNBDState *s = bs->opaque; 243 qemu_free(s->export_name); 244 qemu_free(s->host_spec); 245 246 nbd_teardown_connection(bs); 247 } 248 249 static int64_t nbd_getlength(BlockDriverState *bs) 250 { 251 BDRVNBDState *s = bs->opaque; 252 253 return s->size; 254 } 255 256 static BlockDriver bdrv_nbd = { 257 .format_name = "nbd", 258 .instance_size = sizeof(BDRVNBDState), 259 .bdrv_file_open = nbd_open, 260 .bdrv_read = nbd_read, 261 .bdrv_write = nbd_write, 262 .bdrv_close = nbd_close, 263 .bdrv_getlength = nbd_getlength, 264 .protocol_name = "nbd", 265 }; 266 267 static void bdrv_nbd_init(void) 268 { 269 bdrv_register(&bdrv_nbd); 270 } 271 272 block_init(bdrv_nbd_init); 273