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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>
This commit is contained in:
Laurent Vivier 2010-08-25 22:48:33 +02:00 • committed by Kevin Wolf
parent 2aa326be0d
commit 1d45f8b542
5 changed files with 168 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

118
nbd.c
View file

@ -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)
@ -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] : '.',
@ -322,8 +329,6 @@ 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");
@ -331,10 +336,99 @@ int nbd_receive_negotiate(int csock, off_t *size, size_t *blocksize)
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 (magic != 0x00420281861253LL) {
LOG("Bad magic received");
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 (!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;
}