>On 08/25/2010 03:48 PM, Laurent Vivier wrote:
>> This patch allows to connect Qemu using NBD protocol to an nbd-server
>> using named exports.
>>
>
>Does using a named export make the NBD protocol incompatible with a
>server that doesn't support named exports? IOW, it's essentially a new
>protocol layered underneath of NBD?
Named exports is fully compatible with old nbd-server protocol.
All is done in the "negotiate" part: there is a new magic number which is used
when nbd-server uses named exports, this magic number allows the client to send
a name to select the exported disk. Then client receives disk size and data as
usual.
I have tested this patch with current "qemu-nbd" (witch tcp and unix socket)
and it is working fine.
Regards,
Laurent
>Regards,
>
>Anthony Liguori
>
>> 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<laur...@vivier.eu>
>> ---
>> v3: change sizeof() by strlen()
>> v2: address Kevin comments (CODING STYLE)
>>
>> block/nbd.c | 68 +++++++++++++++++++++++---------
>> nbd.c | 118
>+++++++++++++++++++++++++++++++++++++++++++++++++++------
>> nbd.h | 5 ++-
>> qemu-doc.texi | 7 +++
>> qemu-nbd.c | 4 +-
>> 5 files changed, 169 insertions(+), 33 deletions(-)
>>
>> diff --git a/block/nbd.c b/block/nbd.c
>> index a1ec123..5e9d6cb 100644
>> --- a/block/nbd.c
>> +++ b/block/nbd.c
>> @@ -33,6 +33,8 @@
>> #include<sys/types.h>
>> #include<unistd.h>
>>
>> +#define EN_OPTSTR ":exportname="
>> +
>> typedef struct BDRVNBDState {
>> int sock;
>> off_t size;
>> @@ -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,
>> diff --git a/nbd.c b/nbd.c
>> index a9f295f..30dec8d 100644
>> --- a/nbd.c
>> +++ b/nbd.c
>> @@ -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 (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;
>> }
>> diff --git a/nbd.h b/nbd.h
>> index 5a1fbdf..8ff65a1 100644
>> --- a/nbd.h
>> +++ b/nbd.h
>> @@ -42,6 +42,8 @@ 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);
>> @@ -49,7 +51,8 @@ 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);
>> diff --git a/qemu-doc.texi b/qemu-doc.texi
>> index 55a966f..d7d760f 100644
>> --- a/qemu-doc.texi
>> +++ b/qemu-doc.texi
>> @@ -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
>>
>> diff --git a/qemu-nbd.c b/qemu-nbd.c
>> index 4e607cf..41e5c5d 100644
>> --- a/qemu-nbd.c
>> +++ b/qemu-nbd.c
>> @@ -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) {
>> @@ -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;
>>
>
>
--
--------------------- laur...@vivier.eu ---------------------
"Tout ce qui est impossible reste à accomplir" Jules Verne
"Things are only impossible until they're not" Jean-Luc Picard
