Commit f37708f6 authored by Eric Blake's avatar Eric Blake Committed by Paolo Bonzini
Browse files

nbd: Implement NBD_OPT_GO on server 

NBD_OPT_EXPORT_NAME is lousy: per the NBD protocol, any failure
requires us to close the connection rather than report an error.
Therefore, upstream NBD recently added NBD_OPT_GO as the improved
version of the option that does what we want [1], along with
NBD_OPT_INFO that returns the same information but does not
transition to transmission phase.

[1] https://github.com/NetworkBlockDevice/nbd/blob/extension-info/doc/proto.md



This is a first cut at the information types, and only passes the
same information already available through NBD_OPT_LIST and
NBD_OPT_EXPORT_NAME; items like NBD_INFO_BLOCK_SIZE (and thus any
use of NBD_REP_ERR_BLOCK_SIZE_REQD) are intentionally left for
later patches.

Signed-off-by: default avatarEric Blake <eblake@redhat.com>
Message-Id: <20170707203049.534-7-eblake@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 23e099c3

nbd/server.c

+176 −3
Original line number Diff line number Diff line
@@ -141,6 +141,7 @@ static int nbd_negotiate_send_rep_len(QIOChannel *ioc, uint32_t type, 
    trace_nbd_negotiate_send_rep_len(opt, nbd_opt_lookup(opt),

                                     type, nbd_rep_lookup(type), len);



    assert(len < NBD_MAX_BUFFER_SIZE);

    magic = cpu_to_be64(NBD_REP_MAGIC);

    if (nbd_write(ioc, &magic, sizeof(magic), errp) < 0) {

        error_prepend(errp, "write failed (rep magic): ");
@@ -275,6 +276,8 @@ static int nbd_negotiate_handle_list(NBDClient *client, uint32_t length, 
    return nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, NBD_OPT_LIST, errp);

}



/* Send a reply to NBD_OPT_EXPORT_NAME.

 * Return -errno on error, 0 on success. */

static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length,

                                            uint16_t myflags, bool no_zeroes,

                                            Error **errp)
@@ -323,6 +326,162 @@ static int nbd_negotiate_handle_export_name(NBDClient *client, uint32_t length, 
    return 0;

}



/* Send a single NBD_REP_INFO, with a buffer @buf of @length bytes.

 * The buffer does NOT include the info type prefix.

 * Return -errno on error, 0 if ready to send more. */

static int nbd_negotiate_send_info(NBDClient *client, uint32_t opt,

                                   uint16_t info, uint32_t length, void *buf,

                                   Error **errp)

{

    int rc;



    trace_nbd_negotiate_send_info(info, nbd_info_lookup(info), length);

    rc = nbd_negotiate_send_rep_len(client->ioc, NBD_REP_INFO, opt,

                                    sizeof(info) + length, errp);

    if (rc < 0) {

        return rc;

    }

    cpu_to_be16s(&info);

    if (nbd_write(client->ioc, &info, sizeof(info), errp) < 0) {

        return -EIO;

    }

    if (nbd_write(client->ioc, buf, length, errp) < 0) {

        return -EIO;

    }

    return 0;

}



/* Handle NBD_OPT_INFO and NBD_OPT_GO.

 * Return -errno on error, 0 if ready for next option, and 1 to move

 * into transmission phase.  */

static int nbd_negotiate_handle_info(NBDClient *client, uint32_t length,

                                     uint32_t opt, uint16_t myflags,

                                     Error **errp)

{

    int rc;

    char name[NBD_MAX_NAME_SIZE + 1];

    NBDExport *exp;

    uint16_t requests;

    uint16_t request;

    uint32_t namelen;

    bool sendname = false;

    char buf[sizeof(uint64_t) + sizeof(uint16_t)];

    const char *msg;



    /* Client sends:

        4 bytes: L, name length (can be 0)

        L bytes: export name

        2 bytes: N, number of requests (can be 0)

        N * 2 bytes: N requests

    */

    if (length < sizeof(namelen) + sizeof(requests)) {

        msg = "overall request too short";

        goto invalid;

    }

    if (nbd_read(client->ioc, &namelen, sizeof(namelen), errp) < 0) {

        return -EIO;

    }

    be32_to_cpus(&namelen);

    length -= sizeof(namelen);

    if (namelen > length - sizeof(requests) || (length - namelen) % 2) {

        msg = "name length is incorrect";

        goto invalid;

    }

    if (nbd_read(client->ioc, name, namelen, errp) < 0) {

        return -EIO;

    }

    name[namelen] = '\0';

    length -= namelen;

    trace_nbd_negotiate_handle_export_name_request(name);



    if (nbd_read(client->ioc, &requests, sizeof(requests), errp) < 0) {

        return -EIO;

    }

    be16_to_cpus(&requests);

    length -= sizeof(requests);

    trace_nbd_negotiate_handle_info_requests(requests);

    if (requests != length / sizeof(request)) {

        msg = "incorrect number of  requests for overall length";

        goto invalid;

    }

    while (requests--) {

        if (nbd_read(client->ioc, &request, sizeof(request), errp) < 0) {

            return -EIO;

        }

        be16_to_cpus(&request);

        length -= sizeof(request);

        trace_nbd_negotiate_handle_info_request(request,

                                                nbd_info_lookup(request));

        /* For now, we only care about NBD_INFO_NAME; everything else

         * is either a request we don't know or something we send

         * regardless of request. */

        if (request == NBD_INFO_NAME) {

            sendname = true;

        }

    }



    exp = nbd_export_find(name);

    if (!exp) {

        return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_UNKNOWN,

                                          opt, errp, "export '%s' not present",

                                          name);

    }



    /* Don't bother sending NBD_INFO_NAME unless client requested it */

    if (sendname) {

        rc = nbd_negotiate_send_info(client, opt, NBD_INFO_NAME, length, name,

                                     errp);

        if (rc < 0) {

            return rc;

        }

    }



    /* Send NBD_INFO_DESCRIPTION only if available, regardless of

     * client request */

    if (exp->description) {

        size_t len = strlen(exp->description);



        rc = nbd_negotiate_send_info(client, opt, NBD_INFO_DESCRIPTION,

                                     len, exp->description, errp);

        if (rc < 0) {

            return rc;

        }

    }



    /* Send NBD_INFO_EXPORT always */

    trace_nbd_negotiate_new_style_size_flags(exp->size,

                                             exp->nbdflags | myflags);

    stq_be_p(buf, exp->size);

    stw_be_p(buf + 8, exp->nbdflags | myflags);

    rc = nbd_negotiate_send_info(client, opt, NBD_INFO_EXPORT,

                                 sizeof(buf), buf, errp);

    if (rc < 0) {

        return rc;

    }



    /* Final reply */

    rc = nbd_negotiate_send_rep(client->ioc, NBD_REP_ACK, opt, errp);

    if (rc < 0) {

        return rc;

    }



    if (opt == NBD_OPT_GO) {

        client->exp = exp;

        QTAILQ_INSERT_TAIL(&client->exp->clients, client, next);

        nbd_export_get(client->exp);

        rc = 1;

    }

    return rc;



 invalid:

    if (nbd_drop(client->ioc, length, errp) < 0) {

        return -EIO;

    }

    return nbd_negotiate_send_rep_err(client->ioc, NBD_REP_ERR_INVALID, opt,

                                      errp, "%s", msg);

}





/* Handle NBD_OPT_STARTTLS. Return NULL to drop connection, or else the

 * new channel for all further (now-encrypted) communication. */

static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client,
@@ -380,7 +539,8 @@ static QIOChannel *nbd_negotiate_handle_starttls(NBDClient *client, 
}



/* nbd_negotiate_options

 * Process all NBD_OPT_* client option commands.

 * Process all NBD_OPT_* client option commands, during fixed newstyle

 * negotiation.

 * Return:

 * -errno  on error, errp is set

 * 0       on successful negotiation, errp is not set
@@ -397,7 +557,7 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags, 
    /* Client sends:

        [ 0 ..   3]   client flags



       Then we loop until NBD_OPT_EXPORT_NAME:

       Then we loop until NBD_OPT_EXPORT_NAME or NBD_OPT_GO:

        [ 0 ..   7]   NBD_OPTS_MAGIC

        [ 8 ..  11]   NBD option

        [12 ..  15]   Data length
@@ -524,6 +684,19 @@ static int nbd_negotiate_options(NBDClient *client, uint16_t myflags, 
                                                        myflags, no_zeroes,

                                                        errp);



            case NBD_OPT_INFO:

            case NBD_OPT_GO:

                ret = nbd_negotiate_handle_info(client, length, option,

                                                myflags, errp);

                if (ret == 1) {

                    assert(option == NBD_OPT_GO);

                    return 0;

                }

                if (ret) {

                    return ret;

                }

                break;



            case NBD_OPT_STARTTLS:

                if (nbd_drop(client->ioc, length, errp) < 0) {

                    return -EIO;
@@ -606,7 +779,7 @@ static coroutine_fn int nbd_negotiate(NBDClient *client, Error **errp) 
        [ 0 ..   7]   passwd       ("NBDMAGIC")

        [ 8 ..  15]   magic        (NBD_OPTS_MAGIC)

        [16 ..  17]   server flags (0)

        ....options sent, ending in NBD_OPT_EXPORT_NAME....

        ....options sent, ending in NBD_OPT_EXPORT_NAME or NBD_OPT_GO....

     */



    qio_channel_set_blocking(client->ioc, false, NULL);

nbd/trace-events

+3 −0
Original line number Diff line number Diff line
@@ -33,6 +33,9 @@ nbd_negotiate_send_rep_err(const char *msg) "sending error message \"%s\"" 
nbd_negotiate_send_rep_list(const char *name, const char *desc) "Advertising export name '%s' description '%s'"

nbd_negotiate_handle_export_name(void) "Checking length"

nbd_negotiate_handle_export_name_request(const char *name) "Client requested export '%s'"

nbd_negotiate_send_info(int info, const char *name, uint32_t length) "Sending NBD_REP_INFO type %d (%s) with remaining length %" PRIu32

nbd_negotiate_handle_info_requests(int requests) "Client requested %d items of info"

nbd_negotiate_handle_info_request(int request, const char *name) "Client requested info %d (%s)"

nbd_negotiate_handle_starttls(void) "Setting up TLS"

nbd_negotiate_handle_starttls_handshake(void) "Starting TLS handshake"

nbd_negotiate_options_flags(uint32_t flags) "Received client flags 0x%" PRIx32