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nbd: Introduce NBD named exports.
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This patch allows to connect Qemu using NBD protocol to an nbd-server
using named exports.

For instance, if on the host "isoserver", in /etc/nbd-server/config, you have:

[generic]
[debian-500-ppc-netinst]
        exportname = /ISO/debian-500-powerpc-netinst.iso
[Fedora-10-ppc-netinst]
        exportname = /ISO/Fedora-10-ppc-netinst.iso

You can connect to it, using:

    qemu -cdrom nbd:isoserver:exportname=debian-500-ppc-netinst
    qemu -cdrom nbd:isoserver:exportname=Fedora-10-ppc-netinst

NOTE: you need at least nbd-server 2.9.18

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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@vivier @kevmw
vivier authored and kevmw committed Aug 30, 2010
1 parent 2aa326b commit 1d45f8b
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Showing 5 changed files with 169 additions and 33 deletions.
68 changes: 49 additions & 19 deletions block/nbd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,8 @@
#include <sys/types.h>
#include <unistd.h>

#define EN_OPTSTR ":exportname="

typedef struct BDRVNBDState {
int sock;
off_t size;
Expand All @@ -42,55 +44,83 @@ typedef struct BDRVNBDState {
static int nbd_open(BlockDriverState *bs, const char* filename, int flags)
{
BDRVNBDState *s = bs->opaque;
uint32_t nbdflags;

char *file;
char *name;
const char *host;
const char *unixpath;
int sock;
off_t size;
size_t blocksize;
int ret;
int err = -EINVAL;

file = qemu_strdup(filename);

if (!strstart(filename, "nbd:", &host))
return -EINVAL;
name = strstr(file, EN_OPTSTR);
if (name) {
if (name[strlen(EN_OPTSTR)] == 0) {
goto out;
}
name[0] = 0;
name += strlen(EN_OPTSTR);
}

if (!strstart(file, "nbd:", &host)) {
goto out;
}

if (strstart(host, "unix:", &unixpath)) {

if (unixpath[0] != '/')
return -EINVAL;
if (unixpath[0] != '/') {
goto out;
}

sock = unix_socket_outgoing(unixpath);

} else {
uint16_t port;
uint16_t port = NBD_DEFAULT_PORT;
char *p, *r;
char hostname[128];

pstrcpy(hostname, 128, host);

p = strchr(hostname, ':');
if (p == NULL)
return -EINVAL;
if (p != NULL) {
*p = '\0';
p++;

port = strtol(p, &r, 0);
if (r == p) {
goto out;
}
} else if (name == NULL) {
goto out;
}

*p = '\0';
p++;

port = strtol(p, &r, 0);
if (r == p)
return -EINVAL;
sock = tcp_socket_outgoing(hostname, port);
}

if (sock == -1)
return -errno;
if (sock == -1) {
err = -errno;
goto out;
}

ret = nbd_receive_negotiate(sock, &size, &blocksize);
if (ret == -1)
return -errno;
ret = nbd_receive_negotiate(sock, name, &nbdflags, &size, &blocksize);
if (ret == -1) {
err = -errno;
goto out;
}

s->sock = sock;
s->size = size;
s->blocksize = blocksize;
err = 0;

return 0;
out:
qemu_free(file);
return err;
}

static int nbd_read(BlockDriverState *bs, int64_t sector_num,
Expand Down
118 changes: 106 additions & 12 deletions nbd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,8 @@
#define NBD_SET_SIZE_BLOCKS _IO(0xab, 7)
#define NBD_DISCONNECT _IO(0xab, 8)

#define NBD_OPT_EXPORT_NAME (1 << 0)

/* That's all folks */

#define read_sync(fd, buffer, size) nbd_wr_sync(fd, buffer, size, true)
Expand Down Expand Up @@ -296,22 +298,27 @@ int nbd_negotiate(int csock, off_t size)
return 0;
}

int nbd_receive_negotiate(int csock, off_t *size, size_t *blocksize)
int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, size_t *blocksize)
{
char buf[8 + 8 + 8 + 128];
uint64_t magic;
char buf[256];
uint64_t magic, s;
uint16_t tmp;

TRACE("Receiving negotation.");

if (read_sync(csock, buf, sizeof(buf)) != sizeof(buf)) {
if (read_sync(csock, buf, 8) != 8) {
LOG("read failed");
errno = EINVAL;
return -1;
}

magic = be64_to_cpup((uint64_t*)(buf + 8));
*size = be64_to_cpup((uint64_t*)(buf + 16));
*blocksize = 1024;
buf[8] = '\0';
if (strlen(buf) == 0) {
LOG("server connection closed");
errno = EINVAL;
return -1;
}

TRACE("Magic is %c%c%c%c%c%c%c%c",
qemu_isprint(buf[0]) ? buf[0] : '.',
Expand All @@ -322,19 +329,106 @@ int nbd_receive_negotiate(int csock, off_t *size, size_t *blocksize)
qemu_isprint(buf[5]) ? buf[5] : '.',
qemu_isprint(buf[6]) ? buf[6] : '.',
qemu_isprint(buf[7]) ? buf[7] : '.');
TRACE("Magic is 0x%" PRIx64, magic);
TRACE("Size is %" PRIu64, *size);

if (memcmp(buf, "NBDMAGIC", 8) != 0) {
LOG("Invalid magic received");
errno = EINVAL;
return -1;
}

TRACE("Checking magic");
if (read_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("read failed");
errno = EINVAL;
return -1;
}
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 != 0x49484156454F5054LL) {
LOG("Bad magic received");
errno = EINVAL;
return -1;
}
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("flags read failed");
errno = EINVAL;
return -1;
}
*flags = be16_to_cpu(tmp) << 16;
/* reserved for future use */
if (write_sync(csock, &reserved, sizeof(reserved)) !=
sizeof(reserved)) {
LOG("write failed (reserved)");
errno = EINVAL;
return -1;
}
/* write the export name */
magic = cpu_to_be64(magic);
if (write_sync(csock, &magic, sizeof(magic)) != sizeof(magic)) {
LOG("write failed (magic)");
errno = EINVAL;
return -1;
}
opt = cpu_to_be32(NBD_OPT_EXPORT_NAME);
if (write_sync(csock, &opt, sizeof(opt)) != sizeof(opt)) {
LOG("write failed (opt)");
errno = EINVAL;
return -1;
}
namesize = cpu_to_be32(strlen(name));
if (write_sync(csock, &namesize, sizeof(namesize)) !=
sizeof(namesize)) {
LOG("write failed (namesize)");
errno = EINVAL;
return -1;
}
if (write_sync(csock, (char*)name, strlen(name)) != strlen(name)) {
LOG("write failed (name)");
errno = EINVAL;
return -1;
}
} else {
TRACE("Checking magic (cli_magic)");

if (magic != 0x00420281861253LL) {
LOG("Bad magic received");
errno = EINVAL;
return -1;
}
}

if (read_sync(csock, &s, sizeof(s)) != sizeof(s)) {
LOG("read failed");
errno = EINVAL;
return -1;
}
*size = be64_to_cpu(s);
*blocksize = 1024;
TRACE("Size is %" PRIu64, *size);

if (magic != 0x00420281861253LL) {
LOG("Bad magic received");
if (!name) {
if (read_sync(csock, flags, sizeof(*flags)) != sizeof(*flags)) {
LOG("read failed (flags)");
errno = EINVAL;
return -1;
}
*flags = be32_to_cpup(flags);
} else {
if (read_sync(csock, &tmp, sizeof(tmp)) != sizeof(tmp)) {
LOG("read failed (tmp)");
errno = EINVAL;
return -1;
}
*flags |= be32_to_cpu(tmp);
}
if (read_sync(csock, &buf, 124) != 124) {
LOG("read failed (buf)");
errno = EINVAL;
return -1;
}
Expand Down
5 changes: 4 additions & 1 deletion nbd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -42,14 +42,17 @@ enum {
NBD_CMD_DISC = 2
};

#define NBD_DEFAULT_PORT 10809

size_t nbd_wr_sync(int fd, void *buffer, size_t size, bool do_read);
int tcp_socket_outgoing(const char *address, uint16_t port);
int tcp_socket_incoming(const char *address, uint16_t port);
int unix_socket_outgoing(const char *path);
int unix_socket_incoming(const char *path);

int nbd_negotiate(int csock, off_t size);
int nbd_receive_negotiate(int csock, off_t *size, size_t *blocksize);
int nbd_receive_negotiate(int csock, const char *name, uint32_t *flags,
off_t *size, size_t *blocksize);
int nbd_init(int fd, int csock, off_t size, size_t blocksize);
int nbd_send_request(int csock, struct nbd_request *request);
int nbd_receive_reply(int csock, struct nbd_reply *reply);
Expand Down
7 changes: 7 additions & 0 deletions qemu-doc.texi
View file
Original file line number Diff line number Diff line change
Expand Up @@ -620,6 +620,13 @@ qemu linux1.img -hdb nbd:unix:/tmp/my_socket
qemu linux2.img -hdb nbd:unix:/tmp/my_socket
@end example

If the nbd-server uses named exports (since NBD 2.9.18), you must use the
"exportname" option:
@example
qemu -cdrom nbd:localhost:exportname=debian-500-ppc-netinst
qemu -cdrom nbd:localhost:exportname=openSUSE-11.1-ppc-netinst
@end example

@node pcsys_network
@section Network emulation

Expand Down
4 changes: 3 additions & 1 deletion qemu-nbd.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -230,6 +230,7 @@ int main(int argc, char **argv)
int nb_fds = 0;
int max_fd;
int persistent = 0;
uint32_t nbdflags;

while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
switch (ch) {
Expand Down Expand Up @@ -398,7 +399,8 @@ int main(int argc, char **argv)
goto out;
}

ret = nbd_receive_negotiate(sock, &size, &blocksize);
ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
&size, &blocksize);
if (ret == -1) {
ret = 1;
goto out;
Expand Down

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