aboutsummaryrefslogtreecommitdiff
path: root/nbd/client.c
blob: f07cb4822da0bcf34cca34b6ddec45dd5df23d67 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
/*
 *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
 *
 *  Network Block Device Client Side
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; under version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "nbd-internal.h"

static int nbd_errno_to_system_errno(int err)
{
    switch (err) {
    case NBD_SUCCESS:
        return 0;
    case NBD_EPERM:
        return EPERM;
    case NBD_EIO:
        return EIO;
    case NBD_ENOMEM:
        return ENOMEM;
    case NBD_ENOSPC:
        return ENOSPC;
    case NBD_EINVAL:
    default:
        return EINVAL;
    }
}

/* Definitions for opaque data types */

static QTAILQ_HEAD(, NBDExport) exports = QTAILQ_HEAD_INITIALIZER(exports);

/* That's all folks */

/* Basic flow for negotiation

   Server         Client
   Negotiate

   or

   Server         Client
   Negotiate #1
                  Option
   Negotiate #2

   ----

   followed by

   Server         Client
                  Request
   Response
                  Request
   Response
                  ...
   ...
                  Request (type == 2)

*/

int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
                          off_t *size, Error **errp)
{
    char buf[256];
    uint64_t magic, s;
    uint16_t tmp;
    int rc;

    TRACE("Receiving negotiation.");

    rc = -EINVAL;

    if (read_sync(csock, buf, 8) != 8) {
        error_setg(errp, "Failed to read data");
        goto fail;
    }

    buf[8] = '\0';
    if (strlen(buf) == 0) {
        error_setg(errp, "Server connection closed unexpectedly");
        goto fail;
    }

    TRACE("Magic is %c%c%c%c%c%c%c%c",
          qemu_isprint(buf[0]) ? buf[0] : '.',
          qemu_isprint(buf[1]) ? buf[1] : '.',
          qemu_isprint(buf[2]) ? buf[2] : '.',
          qemu_isprint(buf[3]) ? buf[3] : '.',
          qemu_isprint(buf[4]) ? buf[4] : '.',
          qemu_isprint(buf[5]) ? buf[5] : '.',
          qemu_isprint(buf[6]) ? buf[6] : '.',
          qemu_isprint(buf[7]) ? buf[7] : '.');

    if (memcmp(buf, "NBDMAGIC", 8) != 0) {
        error_setg(errp, "Invalid magic received");
        goto fail;
    }

    if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
        error_setg(errp, "Failed to read magic");
        goto fail;
    }
    magic = be64_to_cpu(magic);
    TRACE("Magic is 0x%" PRIx64, magic);

    if (name) {
        uint32_t reserved = 0;
        uint32_t opt;
        uint32_t namesize;

        TRACE("Checking magic (opts_magic)");
        if (magic != NBD_OPTS_MAGIC) {
            if (magic == NBD_CLIENT_MAGIC) {
                error_setg(errp, "Server does not support export names");
            } else {
                error_setg(errp, "Bad magic received");
            }
            goto fail;
        }
        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
            error_setg(errp, "Failed to read server flags");
            goto fail;
        }
        *flags = be16_to_cpu(tmp) << 16;
        /* reserved for future use */
        if (write_sync(csock, &reserved, sizeof(reserved)) !=
            sizeof(reserved)) {
            error_setg(errp, "Failed to read reserved field");
            goto fail;
        }
        /* write the export name */
        magic = cpu_to_be64(magic);
        if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
            error_setg(errp, "Failed to send export name magic");
            goto fail;
        }
        opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
        if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
            error_setg(errp, "Failed to send export name option number");
            goto fail;
        }
        namesize = cpu_to_be32(strlen(name));
        if (write_sync(csock, &namesize, sizeof(namesize)) !=
            sizeof(namesize)) {
            error_setg(errp, "Failed to send export name length");
            goto fail;
        }
        if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
            error_setg(errp, "Failed to send export name");
            goto fail;
        }
    } else {
        TRACE("Checking magic (cli_magic)");

        if (magic != NBD_CLIENT_MAGIC) {
            if (magic == NBD_OPTS_MAGIC) {
                error_setg(errp, "Server requires an export name");
            } else {
                error_setg(errp, "Bad magic received");
            }
            goto fail;
        }
    }

    if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
        error_setg(errp, "Failed to read export length");
        goto fail;
    }
    *size = be64_to_cpu(s);
    TRACE("Size is %" PRIu64, *size);

    if (!name) {
        if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
            error_setg(errp, "Failed to read export flags");
            goto fail;
        }
        *flags = be32_to_cpup(flags);
    } else {
        if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
            error_setg(errp, "Failed to read export flags");
            goto fail;
        }
        *flags |= be16_to_cpu(tmp);
    }
    if (read_sync(csock, &buf, 124) != 124) {
        error_setg(errp, "Failed to read reserved block");
        goto fail;
    }
    rc = 0;

fail:
    return rc;
}

#ifdef __linux__
int nbd_init(int fd, int csock, uint32_t flags, off_t size)
{
    TRACE("Setting NBD socket");

    if (ioctl(fd, NBD_SET_SOCK, csock) < 0) {
        int serrno = errno;
        LOG("Failed to set NBD socket");
        return -serrno;
    }

    TRACE("Setting block size to %lu", (unsigned long)BDRV_SECTOR_SIZE);

    if (ioctl(fd, NBD_SET_BLKSIZE, (size_t)BDRV_SECTOR_SIZE) < 0) {
        int serrno = errno;
        LOG("Failed setting NBD block size");
        return -serrno;
    }

    TRACE("Setting size to %zd block(s)", (size_t)(size / BDRV_SECTOR_SIZE));

    if (ioctl(fd, NBD_SET_SIZE_BLOCKS, (size_t)(size / BDRV_SECTOR_SIZE)) < 0) {
        int serrno = errno;
        LOG("Failed setting size (in blocks)");
        return -serrno;
    }

    if (ioctl(fd, NBD_SET_FLAGS, flags) < 0) {
        if (errno == ENOTTY) {
            int read_only = (flags & NBD_FLAG_READ_ONLY) != 0;
            TRACE("Setting readonly attribute");

            if (ioctl(fd, BLKROSET, (unsigned long) &read_only) < 0) {
                int serrno = errno;
                LOG("Failed setting read-only attribute");
                return -serrno;
            }
        } else {
            int serrno = errno;
            LOG("Failed setting flags");
            return -serrno;
        }
    }

    TRACE("Negotiation ended");

    return 0;
}

int nbd_client(int fd)
{
    int ret;
    int serrno;

    TRACE("Doing NBD loop");

    ret = ioctl(fd, NBD_DO_IT);
    if (ret < 0 && errno == EPIPE) {
        /* NBD_DO_IT normally returns EPIPE when someone has disconnected
         * the socket via NBD_DISCONNECT.  We do not want to return 1 in
         * that case.
         */
        ret = 0;
    }
    serrno = errno;

    TRACE("NBD loop returned %d: %s", ret, strerror(serrno));

    TRACE("Clearing NBD queue");
    ioctl(fd, NBD_CLEAR_QUE);

    TRACE("Clearing NBD socket");
    ioctl(fd, NBD_CLEAR_SOCK);

    errno = serrno;
    return ret;
}
#else
int nbd_init(int fd, int csock, uint32_t flags, off_t size)
{
    return -ENOTSUP;
}

int nbd_client(int fd)
{
    return -ENOTSUP;
}
#endif

ssize_t nbd_send_request(int csock, struct nbd_request *request)
{
    uint8_t buf[NBD_REQUEST_SIZE];
    ssize_t ret;

    cpu_to_be32w((uint32_t*)buf, NBD_REQUEST_MAGIC);
    cpu_to_be32w((uint32_t*)(buf + 4), request->type);
    cpu_to_be64w((uint64_t*)(buf + 8), request->handle);
    cpu_to_be64w((uint64_t*)(buf + 16), request->from);
    cpu_to_be32w((uint32_t*)(buf + 24), request->len);

    TRACE("Sending request to client: "
          "{ .from = %" PRIu64", .len = %u, .handle = %" PRIu64", .type=%i}",
          request->from, request->len, request->handle, request->type);

    ret = write_sync(csock, buf, sizeof(buf));
    if (ret < 0) {
        return ret;
    }

    if (ret != sizeof(buf)) {
        LOG("writing to socket failed");
        return -EINVAL;
    }
    return 0;
}

ssize_t nbd_receive_reply(int csock, struct nbd_reply *reply)
{
    uint8_t buf[NBD_REPLY_SIZE];
    uint32_t magic;
    ssize_t ret;

    ret = read_sync(csock, buf, sizeof(buf));
    if (ret < 0) {
        return ret;
    }

    if (ret != sizeof(buf)) {
        LOG("read failed");
        return -EINVAL;
    }

    /* Reply
       [ 0 ..  3]    magic   (NBD_REPLY_MAGIC)
       [ 4 ..  7]    error   (0 == no error)
       [ 7 .. 15]    handle
     */

    magic = be32_to_cpup((uint32_t*)buf);
    reply->error  = be32_to_cpup((uint32_t*)(buf + 4));
    reply->handle = be64_to_cpup((uint64_t*)(buf + 8));

    reply->error = nbd_errno_to_system_errno(reply->error);

    TRACE("Got reply: "
          "{ magic = 0x%x, .error = %d, handle = %" PRIu64" }",
          magic, reply->error, reply->handle);

    if (magic != NBD_REPLY_MAGIC) {
        LOG("invalid magic (got 0x%x)", magic);
        return -EINVAL;
    }
    return 0;
}