ctdbd_conn: Simplify two DEBUGs

[Samba.git] / source3 / lib / ctdbd_conn.c

/* 
   Unix SMB/CIFS implementation.
   Samba internal messaging functions
   Copyright (C) 2007 by Volker Lendecke
   Copyright (C) 2007 by Andrew Tridgell

   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; either version 3 of the License, or
   (at your option) any later version.

   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 "replace.h"
#include "util_tdb.h"
#include "serverid.h"
#include "ctdbd_conn.h"
#include "system/select.h"
#include "lib/util/sys_rw_data.h"
#include "lib/util/iov_buf.h"
#include "lib/util/select.h"
#include "lib/util/debug.h"
#include "lib/util/talloc_stack.h"
#include "lib/util/genrand.h"
#include "lib/util/fault.h"

#include "messages.h"

/* paths to these include files come from --with-ctdb= in configure */

#include "ctdb_private.h"

struct ctdbd_srvid_cb {
        uint64_t srvid;
        int (*cb)(uint32_t src_vnn, uint32_t dst_vnn,
                  uint64_t dst_srvid,
                  const uint8_t *msg, size_t msglen,
                  void *private_data);
        void *private_data;
};

struct ctdbd_connection {
        const char *sockname;   /* Needed in ctdbd_traverse */
        struct messaging_context *msg_ctx;
        uint32_t reqid;
        uint32_t our_vnn;
        uint64_t rand_srvid;
        struct ctdbd_srvid_cb *callbacks;
        int fd;
        struct tevent_fd *fde;
        int timeout;
};

static uint32_t ctdbd_next_reqid(struct ctdbd_connection *conn)
{
        conn->reqid += 1;
        if (conn->reqid == 0) {
                conn->reqid += 1;
        }
        return conn->reqid;
}

static int ctdbd_control(struct ctdbd_connection *conn,
                         uint32_t vnn, uint32_t opcode,
                         uint64_t srvid, uint32_t flags,
                         TDB_DATA data,
                         TALLOC_CTX *mem_ctx, TDB_DATA *outdata,
                         int32_t *cstatus);

/*
 * exit on fatal communications errors with the ctdbd daemon
 */
static void cluster_fatal(const char *why)
{
        DEBUG(0,("cluster fatal event: %s - exiting immediately\n", why));
        /* we don't use smb_panic() as we don't want to delay to write
           a core file. We need to release this process id immediately
           so that someone else can take over without getting sharing
           violations */
        _exit(1);
}

/*
 *
 */
static void ctdb_packet_dump(struct ctdb_req_header *hdr)
{
        if (DEBUGLEVEL < 11) {
                return;
        }
        DEBUGADD(11, ("len=%d, magic=%x, vers=%d, gen=%d, op=%d, reqid=%d\n",
                      (int)hdr->length, (int)hdr->ctdb_magic,
                      (int)hdr->ctdb_version, (int)hdr->generation,
                      (int)hdr->operation, (int)hdr->reqid));
}

/*
 * Register a srvid with ctdbd
 */
int register_with_ctdbd(struct ctdbd_connection *conn, uint64_t srvid,
                        int (*cb)(uint32_t src_vnn, uint32_t dst_vnn,
                                  uint64_t dst_srvid,
                                  const uint8_t *msg, size_t msglen,
                                  void *private_data),
                        void *private_data)
{

        int ret;
        int32_t cstatus;
        size_t num_callbacks;
        struct ctdbd_srvid_cb *tmp;

        ret = ctdbd_control_local(conn, CTDB_CONTROL_REGISTER_SRVID, srvid, 0,
                                  tdb_null, NULL, NULL, &cstatus);
        if (ret != 0) {
                return ret;
        }

        num_callbacks = talloc_array_length(conn->callbacks);

        tmp = talloc_realloc(conn, conn->callbacks, struct ctdbd_srvid_cb,
                             num_callbacks + 1);
        if (tmp == NULL) {
                return ENOMEM;
        }
        conn->callbacks = tmp;

        conn->callbacks[num_callbacks] = (struct ctdbd_srvid_cb) {
                .srvid = srvid, .cb = cb, .private_data = private_data
        };

        return 0;
}

static int ctdbd_msg_call_back(struct ctdbd_connection *conn,
                               struct ctdb_req_message_old *msg)
{
        uint32_t msg_len;
        size_t i, num_callbacks;

        msg_len = msg->hdr.length;
        if (msg_len < offsetof(struct ctdb_req_message_old, data)) {
                DBG_DEBUG("len %"PRIu32" too small\n", msg_len);
                return 0;
        }
        msg_len -= offsetof(struct ctdb_req_message_old, data);

        if (msg_len < msg->datalen) {
                DBG_DEBUG("msg_len=%"PRIu32" < msg->datalen=%"PRIu32"\n",
                          msg_len, msg->datalen);
                return 0;
        }

        num_callbacks = talloc_array_length(conn->callbacks);

        for (i=0; i<num_callbacks; i++) {
                struct ctdbd_srvid_cb *cb = &conn->callbacks[i];

                if ((cb->srvid == msg->srvid) && (cb->cb != NULL)) {
                        int ret;

                        ret = cb->cb(msg->hdr.srcnode, msg->hdr.destnode,
                                     msg->srvid, msg->data, msg->datalen,
                                     cb->private_data);
                        if (ret != 0) {
                                return ret;
                        }
                }
        }
        return 0;
}

/*
 * get our vnn from the cluster
 */
static int get_cluster_vnn(struct ctdbd_connection *conn, uint32_t *vnn)
{
        int32_t cstatus=-1;
        int ret;
        ret = ctdbd_control_local(conn, CTDB_CONTROL_GET_PNN, 0, 0,
                                  tdb_null, NULL, NULL, &cstatus);
        if (ret != 0) {
                DEBUG(1, ("ctdbd_control failed: %s\n", strerror(ret)));
                return ret;
        }
        *vnn = (uint32_t)cstatus;
        return ret;
}

/*
 * Are we active (i.e. not banned or stopped?)
 */
static bool ctdbd_working(struct ctdbd_connection *conn, uint32_t vnn)
{
        int32_t cstatus=-1;
        TDB_DATA outdata;
        struct ctdb_node_map_old *m;
        uint32_t failure_flags;
        bool ok = false;
        uint32_t i;
        int ret;

        ret = ctdbd_control_local(conn, CTDB_CONTROL_GET_NODEMAP, 0, 0,
                                  tdb_null, talloc_tos(), &outdata, &cstatus);
        if (ret != 0) {
                DEBUG(1, ("ctdbd_control failed: %s\n", strerror(ret)));
                return false;
        }
        if ((cstatus != 0) || (outdata.dptr == NULL)) {
                DEBUG(2, ("Received invalid ctdb data\n"));
                return false;
        }

        m = (struct ctdb_node_map_old *)outdata.dptr;

        for (i=0; i<m->num; i++) {
                if (vnn == m->nodes[i].pnn) {
                        break;
                }
        }

        if (i == m->num) {
                DEBUG(2, ("Did not find ourselves (node %d) in nodemap\n",
                          (int)vnn));
                goto fail;
        }

        failure_flags = NODE_FLAGS_BANNED | NODE_FLAGS_DISCONNECTED
                | NODE_FLAGS_PERMANENTLY_DISABLED | NODE_FLAGS_STOPPED;

        if ((m->nodes[i].flags & failure_flags) != 0) {
                DEBUG(2, ("Node has status %x, not active\n",
                          (int)m->nodes[i].flags));
                goto fail;
        }

        ok = true;
fail:
        TALLOC_FREE(outdata.dptr);
        return ok;
}

uint32_t ctdbd_vnn(const struct ctdbd_connection *conn)
{
        return conn->our_vnn;
}

/*
 * Get us a ctdb connection
 */

static int ctdbd_connect(const char *sockname, int *pfd)
{
        struct sockaddr_un addr = { 0, };
        int fd;
        socklen_t salen;
        size_t namelen;

        fd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (fd == -1) {
                int err = errno;
                DEBUG(3, ("Could not create socket: %s\n", strerror(err)));
                return err;
        }

        addr.sun_family = AF_UNIX;

        namelen = strlcpy(addr.sun_path, sockname, sizeof(addr.sun_path));
        if (namelen >= sizeof(addr.sun_path)) {
                DEBUG(3, ("%s: Socket name too long: %s\n", __func__,
                          sockname));
                close(fd);
                return ENAMETOOLONG;
        }

        salen = sizeof(struct sockaddr_un);

        if (connect(fd, (struct sockaddr *)(void *)&addr, salen) == -1) {
                int err = errno;
                DEBUG(1, ("connect(%s) failed: %s\n", sockname,
                          strerror(err)));
                close(fd);
                return err;
        }

        *pfd = fd;
        return 0;
}

static int ctdb_read_packet(int fd, int timeout, TALLOC_CTX *mem_ctx,
                            struct ctdb_req_header **result)
{
        struct ctdb_req_header *req;
        uint32_t msglen;
        ssize_t nread;

        if (timeout != -1) {
                struct pollfd pfd = { .fd = fd, .events = POLLIN };
                int ret;

                ret = sys_poll_intr(&pfd, 1, timeout);
                if (ret == -1) {
                        return errno;
                }
                if (ret == 0) {
                        return ETIMEDOUT;
                }
                if (ret != 1) {
                        return EIO;
                }
        }

        nread = read_data(fd, &msglen, sizeof(msglen));
        if (nread == -1) {
                return errno;
        }
        if (nread == 0) {
                return EIO;
        }

        if (msglen < sizeof(struct ctdb_req_header)) {
                return EIO;
        }

        req = talloc_size(mem_ctx, msglen);
        if (req == NULL) {
                return ENOMEM;
        }
        talloc_set_name_const(req, "struct ctdb_req_header");

        req->length = msglen;

        nread = read_data(fd, ((char *)req) + sizeof(msglen),
                          msglen - sizeof(msglen));
        if (nread == -1) {
                TALLOC_FREE(req);
                return errno;
        }
        if (nread == 0) {
                TALLOC_FREE(req);
                return EIO;
        }

        *result = req;
        return 0;
}

/*
 * Read a full ctdbd request. If we have a messaging context, defer incoming
 * messages that might come in between.
 */

static int ctdb_read_req(struct ctdbd_connection *conn, uint32_t reqid,
                         TALLOC_CTX *mem_ctx, struct ctdb_req_header **result)
{
        struct ctdb_req_header *hdr;
        int ret;

 next_pkt:

        ret = ctdb_read_packet(conn->fd, conn->timeout, mem_ctx, &hdr);
        if (ret != 0) {
                DEBUG(0, ("ctdb_read_packet failed: %s\n", strerror(ret)));
                cluster_fatal("ctdbd died\n");
        }

        DEBUG(11, ("Received ctdb packet\n"));
        ctdb_packet_dump(hdr);

        if (hdr->operation == CTDB_REQ_MESSAGE) {
                struct ctdb_req_message_old *msg = (struct ctdb_req_message_old *)hdr;

                if (conn->msg_ctx == NULL) {
                        DEBUG(1, ("Got a message without having a msg ctx, "
                                  "dropping msg %llu\n",
                                  (long long unsigned)msg->srvid));
                        TALLOC_FREE(hdr);
                        goto next_pkt;
                }

                ret = ctdbd_msg_call_back(conn, msg);
                if (ret != 0) {
                        TALLOC_FREE(hdr);
                        return ret;
                }

                TALLOC_FREE(hdr);
                goto next_pkt;
        }

        if ((reqid != 0) && (hdr->reqid != reqid)) {
                /* we got the wrong reply */
                DEBUG(0,("Discarding mismatched ctdb reqid %u should have "
                         "been %u\n", hdr->reqid, reqid));
                TALLOC_FREE(hdr);
                goto next_pkt;
        }

        *result = talloc_move(mem_ctx, &hdr);

        return 0;
}

static int ctdbd_connection_destructor(struct ctdbd_connection *c)
{
        TALLOC_FREE(c->fde);
        if (c->fd != -1) {
                close(c->fd);
                c->fd = -1;
        }
        return 0;
}
/*
 * Get us a ctdbd connection
 */

int ctdbd_init_connection(TALLOC_CTX *mem_ctx,
                          const char *sockname, int timeout,
                          struct ctdbd_connection **pconn)
{
        struct ctdbd_connection *conn;
        int ret;

        if (!(conn = talloc_zero(mem_ctx, struct ctdbd_connection))) {
                DEBUG(0, ("talloc failed\n"));
                return ENOMEM;
        }

        conn->sockname = talloc_strdup(conn, sockname);
        if (conn->sockname == NULL) {
                DBG_ERR("talloc failed\n");
                ret = ENOMEM;
                goto fail;
        }

        conn->timeout = timeout;

        if (conn->timeout == 0) {
                conn->timeout = -1;
        }

        ret = ctdbd_connect(conn->sockname, &conn->fd);
        if (ret != 0) {
                DEBUG(1, ("ctdbd_connect failed: %s\n", strerror(ret)));
                goto fail;
        }
        talloc_set_destructor(conn, ctdbd_connection_destructor);

        ret = get_cluster_vnn(conn, &conn->our_vnn);

        if (ret != 0) {
                DEBUG(10, ("get_cluster_vnn failed: %s\n", strerror(ret)));
                goto fail;
        }

        if (!ctdbd_working(conn, conn->our_vnn)) {
                DEBUG(2, ("Node is not working, can not connect\n"));
                ret = EIO;
                goto fail;
        }

        generate_random_buffer((unsigned char *)&conn->rand_srvid,
                               sizeof(conn->rand_srvid));

        ret = register_with_ctdbd(conn, conn->rand_srvid, NULL, NULL);

        if (ret != 0) {
                DEBUG(5, ("Could not register random srvid: %s\n",
                          strerror(ret)));
                goto fail;
        }

        *pconn = conn;
        return 0;

 fail:
        TALLOC_FREE(conn);
        return ret;
}

struct messaging_context *ctdb_conn_msg_ctx(struct ctdbd_connection *conn)
{
        return conn->msg_ctx;
}

int ctdbd_conn_get_fd(struct ctdbd_connection *conn)
{
        return conn->fd;
}

/*
 * Packet handler to receive and handle a ctdb message
 */
static int ctdb_handle_message(struct ctdbd_connection *conn,
                               struct ctdb_req_header *hdr)
{
        struct ctdb_req_message_old *msg;

        if (hdr->operation != CTDB_REQ_MESSAGE) {
                DEBUG(0, ("Received async msg of type %u, discarding\n",
                          hdr->operation));
                return EINVAL;
        }

        msg = (struct ctdb_req_message_old *)hdr;

        ctdbd_msg_call_back(conn, msg);

        return 0;
}

/*
 * The ctdbd socket is readable asynchronuously
 */

static void ctdbd_socket_handler(struct tevent_context *event_ctx,
                                 struct tevent_fd *event,
                                 uint16_t flags,
                                 void *private_data)
{
        struct ctdbd_connection *conn = talloc_get_type_abort(
                private_data, struct ctdbd_connection);
        struct ctdb_req_header *hdr = NULL;
        int ret;

        ret = ctdb_read_packet(conn->fd, conn->timeout, talloc_tos(), &hdr);
        if (ret != 0) {
                DEBUG(0, ("ctdb_read_packet failed: %s\n", strerror(ret)));
                cluster_fatal("ctdbd died\n");
        }

        ret = ctdb_handle_message(conn, hdr);

        TALLOC_FREE(hdr);

        if (ret != 0) {
                DEBUG(10, ("could not handle incoming message: %s\n",
                           strerror(ret)));
        }
}

/*
 * Prepare a ctdbd connection to receive messages
 */

int ctdbd_register_msg_ctx(struct ctdbd_connection *conn,
                           struct messaging_context *msg_ctx,
                           struct tevent_context *ev)
{
        SMB_ASSERT(conn->msg_ctx == NULL);
        SMB_ASSERT(conn->fde == NULL);

        conn->fde = tevent_add_fd(ev, conn, conn->fd, TEVENT_FD_READ,
                                  ctdbd_socket_handler, conn);
        if (conn->fde == NULL) {
                DEBUG(0, ("event_add_fd failed\n"));
                return ENOMEM;
        }

        conn->msg_ctx = msg_ctx;

        return 0;
}

int ctdbd_messaging_send_iov(struct ctdbd_connection *conn,
                             uint32_t dst_vnn, uint64_t dst_srvid,
                             const struct iovec *iov, int iovlen)
{
        struct ctdb_req_message_old r;
        struct iovec iov2[iovlen+1];
        size_t buflen = iov_buflen(iov, iovlen);
        ssize_t nwritten;

        r.hdr.length = offsetof(struct ctdb_req_message_old, data) + buflen;
        r.hdr.ctdb_magic = CTDB_MAGIC;
        r.hdr.ctdb_version = CTDB_PROTOCOL;
        r.hdr.generation = 1;
        r.hdr.operation  = CTDB_REQ_MESSAGE;
        r.hdr.destnode   = dst_vnn;
        r.hdr.srcnode    = conn->our_vnn;
        r.hdr.reqid      = 0;
        r.srvid          = dst_srvid;
        r.datalen        = buflen;

        DEBUG(10, ("ctdbd_messaging_send: Sending ctdb packet\n"));
        ctdb_packet_dump(&r.hdr);

        iov2[0].iov_base = &r;
        iov2[0].iov_len = offsetof(struct ctdb_req_message_old, data);
        memcpy(&iov2[1], iov, iovlen * sizeof(struct iovec));

        nwritten = write_data_iov(conn->fd, iov2, iovlen+1);
        if (nwritten == -1) {
                DEBUG(3, ("write_data_iov failed: %s\n", strerror(errno)));
                cluster_fatal("cluster dispatch daemon msg write error\n");
        }

        return 0;
}

/*
 * send/recv a generic ctdb control message
 */
static int ctdbd_control(struct ctdbd_connection *conn,
                         uint32_t vnn, uint32_t opcode,
                         uint64_t srvid, uint32_t flags,
                         TDB_DATA data,
                         TALLOC_CTX *mem_ctx, TDB_DATA *outdata,
                         int32_t *cstatus)
{
        struct ctdb_req_control_old req;
        struct ctdb_req_header *hdr;
        struct ctdb_reply_control_old *reply = NULL;
        struct iovec iov[2];
        ssize_t nwritten;
        int ret;

        ZERO_STRUCT(req);
        req.hdr.length = offsetof(struct ctdb_req_control_old, data) + data.dsize;
        req.hdr.ctdb_magic   = CTDB_MAGIC;
        req.hdr.ctdb_version = CTDB_PROTOCOL;
        req.hdr.operation    = CTDB_REQ_CONTROL;
        req.hdr.reqid        = ctdbd_next_reqid(conn);
        req.hdr.destnode     = vnn;
        req.opcode           = opcode;
        req.srvid            = srvid;
        req.datalen          = data.dsize;
        req.flags            = flags;

        DBG_DEBUG("Sending ctdb packet reqid=%"PRIu32", vnn=%"PRIu32", "
                  "opcode=%"PRIu32", srvid=%"PRIu64"\n", req.hdr.reqid,
                  req.hdr.destnode, req.opcode, req.srvid);
        ctdb_packet_dump(&req.hdr);

        iov[0].iov_base = &req;
        iov[0].iov_len = offsetof(struct ctdb_req_control_old, data);
        iov[1].iov_base = data.dptr;
        iov[1].iov_len = data.dsize;

        nwritten = write_data_iov(conn->fd, iov, ARRAY_SIZE(iov));
        if (nwritten == -1) {
                DEBUG(3, ("write_data_iov failed: %s\n", strerror(errno)));
                cluster_fatal("cluster dispatch daemon msg write error\n");
        }

        if (flags & CTDB_CTRL_FLAG_NOREPLY) {
                if (cstatus) {
                        *cstatus = 0;
                }
                return 0;
        }

        ret = ctdb_read_req(conn, req.hdr.reqid, NULL, &hdr);
        if (ret != 0) {
                DEBUG(10, ("ctdb_read_req failed: %s\n", strerror(ret)));
                return ret;
        }

        if (hdr->operation != CTDB_REPLY_CONTROL) {
                DEBUG(0, ("received invalid reply\n"));
                TALLOC_FREE(hdr);
                return EIO;
        }
        reply = (struct ctdb_reply_control_old *)hdr;

        if (outdata) {
                if (!(outdata->dptr = (uint8_t *)talloc_memdup(
                              mem_ctx, reply->data, reply->datalen))) {
                        TALLOC_FREE(reply);
                        return ENOMEM;
                }
                outdata->dsize = reply->datalen;
        }
        if (cstatus) {
                (*cstatus) = reply->status;
        }

        TALLOC_FREE(reply);
        return ret;
}

/*
 * see if a remote process exists
 */
bool ctdbd_process_exists(struct ctdbd_connection *conn, uint32_t vnn, pid_t pid)
{
        int32_t cstatus = 0;
        int ret;

        ret = ctdbd_control(conn, vnn, CTDB_CONTROL_PROCESS_EXISTS, 0, 0,
                            (TDB_DATA) { .dptr = (uint8_t *)&pid,
                                         .dsize = sizeof(pid) },
                            NULL, NULL, &cstatus);
        if (ret != 0) {
                return false;
        }
        return (cstatus == 0);
}

/*
 * Get a db path
 */
char *ctdbd_dbpath(struct ctdbd_connection *conn,
                   TALLOC_CTX *mem_ctx, uint32_t db_id)
{
        int ret;
        TDB_DATA data;
        TDB_DATA rdata = {0};
        int32_t cstatus = 0;

        data.dptr = (uint8_t*)&db_id;
        data.dsize = sizeof(db_id);

        ret = ctdbd_control_local(conn, CTDB_CONTROL_GETDBPATH, 0, 0, data,
                                  mem_ctx, &rdata, &cstatus);
        if ((ret != 0) || cstatus != 0) {
                DEBUG(0, (__location__ " ctdb_control for getdbpath failed: %s\n",
                          strerror(ret)));
                return NULL;
        }

        return (char *)rdata.dptr;
}

/*
 * attach to a ctdb database
 */
int ctdbd_db_attach(struct ctdbd_connection *conn,
                    const char *name, uint32_t *db_id, int tdb_flags)
{
        int ret;
        TDB_DATA data;
        int32_t cstatus;
        bool persistent = (tdb_flags & TDB_CLEAR_IF_FIRST) == 0;

        data = string_term_tdb_data(name);

        ret = ctdbd_control_local(conn,
                                  persistent
                                  ? CTDB_CONTROL_DB_ATTACH_PERSISTENT
                                  : CTDB_CONTROL_DB_ATTACH,
                                  tdb_flags, 0, data, NULL, &data, &cstatus);
        if (ret != 0) {
                DEBUG(0, (__location__ " ctdb_control for db_attach "
                          "failed: %s\n", strerror(ret)));
                return ret;
        }

        if (cstatus != 0 || data.dsize != sizeof(uint32_t)) {
                DEBUG(0,(__location__ " ctdb_control for db_attach failed\n"));
                return EIO;
        }

        *db_id = *(uint32_t *)data.dptr;
        talloc_free(data.dptr);

        if (!(tdb_flags & TDB_SEQNUM)) {
                return 0;
        }

        data.dptr = (uint8_t *)db_id;
        data.dsize = sizeof(*db_id);

        ret = ctdbd_control_local(conn, CTDB_CONTROL_ENABLE_SEQNUM, 0, 0, data,
                                  NULL, NULL, &cstatus);
        if ((ret != 0) || cstatus != 0) {
                DEBUG(0, (__location__ " ctdb_control for enable seqnum "
                          "failed: %s\n", strerror(ret)));
                return (ret == 0) ? EIO : ret;
        }

        return 0;
}

/*
 * force the migration of a record to this node
 */
int ctdbd_migrate(struct ctdbd_connection *conn, uint32_t db_id, TDB_DATA key)
{
        struct ctdb_req_call_old req;
        struct ctdb_req_header *hdr;
        struct iovec iov[2];
        ssize_t nwritten;
        int ret;

        ZERO_STRUCT(req);

        req.hdr.length = offsetof(struct ctdb_req_call_old, data) + key.dsize;
        req.hdr.ctdb_magic   = CTDB_MAGIC;
        req.hdr.ctdb_version = CTDB_PROTOCOL;
        req.hdr.operation    = CTDB_REQ_CALL;
        req.hdr.reqid        = ctdbd_next_reqid(conn);
        req.flags            = CTDB_IMMEDIATE_MIGRATION;
        req.callid           = CTDB_NULL_FUNC;
        req.db_id            = db_id;
        req.keylen           = key.dsize;

        DEBUG(10, ("ctdbd_migrate: Sending ctdb packet\n"));
        ctdb_packet_dump(&req.hdr);

        iov[0].iov_base = &req;
        iov[0].iov_len = offsetof(struct ctdb_req_call_old, data);
        iov[1].iov_base = key.dptr;
        iov[1].iov_len = key.dsize;

        nwritten = write_data_iov(conn->fd, iov, ARRAY_SIZE(iov));
        if (nwritten == -1) {
                DEBUG(3, ("write_data_iov failed: %s\n", strerror(errno)));
                cluster_fatal("cluster dispatch daemon msg write error\n");
        }

        ret = ctdb_read_req(conn, req.hdr.reqid, NULL, &hdr);
        if (ret != 0) {
                DEBUG(10, ("ctdb_read_req failed: %s\n", strerror(ret)));
                goto fail;
        }

        if (hdr->operation != CTDB_REPLY_CALL) {
                DEBUG(0, ("received invalid reply\n"));
                goto fail;
        }

 fail:

        TALLOC_FREE(hdr);
        return ret;
}

/*
 * Fetch a record and parse it
 */
int ctdbd_parse(struct ctdbd_connection *conn, uint32_t db_id,
                TDB_DATA key, bool local_copy,
                void (*parser)(TDB_DATA key, TDB_DATA data,
                               void *private_data),
                void *private_data)
{
        struct ctdb_req_call_old req;
        struct ctdb_req_header *hdr = NULL;
        struct ctdb_reply_call_old *reply;
        struct iovec iov[2];
        ssize_t nwritten;
        uint32_t flags;
        int ret;

        flags = local_copy ? CTDB_WANT_READONLY : 0;

        ZERO_STRUCT(req);

        req.hdr.length = offsetof(struct ctdb_req_call_old, data) + key.dsize;
        req.hdr.ctdb_magic   = CTDB_MAGIC;
        req.hdr.ctdb_version = CTDB_PROTOCOL;
        req.hdr.operation    = CTDB_REQ_CALL;
        req.hdr.reqid        = ctdbd_next_reqid(conn);
        req.flags            = flags;
        req.callid           = CTDB_FETCH_FUNC;
        req.db_id            = db_id;
        req.keylen           = key.dsize;

        iov[0].iov_base = &req;
        iov[0].iov_len = offsetof(struct ctdb_req_call_old, data);
        iov[1].iov_base = key.dptr;
        iov[1].iov_len = key.dsize;

        nwritten = write_data_iov(conn->fd, iov, ARRAY_SIZE(iov));
        if (nwritten == -1) {
                DEBUG(3, ("write_data_iov failed: %s\n", strerror(errno)));
                cluster_fatal("cluster dispatch daemon msg write error\n");
        }

        ret = ctdb_read_req(conn, req.hdr.reqid, NULL, &hdr);
        if (ret != 0) {
                DEBUG(10, ("ctdb_read_req failed: %s\n", strerror(ret)));
                goto fail;
        }

        if ((hdr == NULL) || (hdr->operation != CTDB_REPLY_CALL)) {
                DEBUG(0, ("received invalid reply\n"));
                ret = EIO;
                goto fail;
        }
        reply = (struct ctdb_reply_call_old *)hdr;

        if (reply->datalen == 0) {
                /*
                 * Treat an empty record as non-existing
                 */
                ret = ENOENT;
                goto fail;
        }

        parser(key, make_tdb_data(&reply->data[0], reply->datalen),
               private_data);

        ret = 0;
 fail:
        TALLOC_FREE(hdr);
        return ret;
}

/*
  Traverse a ctdb database. "conn" must be an otherwise unused
  ctdb_connection where no other messages but the traverse ones are
  expected.
*/

int ctdbd_traverse(struct ctdbd_connection *conn, uint32_t db_id,
                        void (*fn)(TDB_DATA key, TDB_DATA data,
                                   void *private_data),
                        void *private_data)
{
        int ret;
        TDB_DATA key, data;
        struct ctdb_traverse_start t;
        int32_t cstatus;

        t.db_id = db_id;
        t.srvid = conn->rand_srvid;
        t.reqid = ctdbd_next_reqid(conn);

        data.dptr = (uint8_t *)&t;
        data.dsize = sizeof(t);

        ret = ctdbd_control_local(conn, CTDB_CONTROL_TRAVERSE_START,
                                  conn->rand_srvid,
                                  0, data, NULL, NULL, &cstatus);

        if ((ret != 0) || (cstatus != 0)) {
                DEBUG(0,("ctdbd_control failed: %s, %d\n", strerror(ret),
                         cstatus));

                if (ret == 0) {
                        /*
                         * We need a mapping here
                         */
                        ret = EIO;
                }
                return ret;
        }

        while (true) {
                struct ctdb_req_header *hdr = NULL;
                struct ctdb_req_message_old *m;
                struct ctdb_rec_data_old *d;

                ret = ctdb_read_packet(conn->fd, conn->timeout, conn, &hdr);
                if (ret != 0) {
                        DEBUG(0, ("ctdb_read_packet failed: %s\n",
                                  strerror(ret)));
                        cluster_fatal("ctdbd died\n");
                }

                if (hdr->operation != CTDB_REQ_MESSAGE) {
                        DEBUG(0, ("Got operation %u, expected a message\n",
                                  (unsigned)hdr->operation));
                        return EIO;
                }

                m = (struct ctdb_req_message_old *)hdr;
                d = (struct ctdb_rec_data_old *)&m->data[0];
                if (m->datalen < sizeof(uint32_t) || m->datalen != d->length) {
                        DEBUG(0, ("Got invalid traverse data of length %d\n",
                                  (int)m->datalen));
                        return EIO;
                }

                key.dsize = d->keylen;
                key.dptr  = &d->data[0];
                data.dsize = d->datalen;
                data.dptr = &d->data[d->keylen];

                if (key.dsize == 0 && data.dsize == 0) {
                        /* end of traverse */
                        return 0;
                }

                if (data.dsize < sizeof(struct ctdb_ltdb_header)) {
                        DEBUG(0, ("Got invalid ltdb header length %d\n",
                                  (int)data.dsize));
                        return EIO;
                }
                data.dsize -= sizeof(struct ctdb_ltdb_header);
                data.dptr += sizeof(struct ctdb_ltdb_header);

                if (fn != NULL) {
                        fn(key, data, private_data);
                }
        }
        return 0;
}

/*
   This is used to canonicalize a ctdb_sock_addr structure.
*/
static void smbd_ctdb_canonicalize_ip(const struct sockaddr_storage *in,
                                      struct sockaddr_storage *out)
{
        memcpy(out, in, sizeof (*out));

#ifdef HAVE_IPV6
        if (in->ss_family == AF_INET6) {
                const char prefix[12] = { 0,0,0,0,0,0,0,0,0,0,0xff,0xff };
                const struct sockaddr_in6 *in6 =
                        (const struct sockaddr_in6 *)in;
                struct sockaddr_in *out4 = (struct sockaddr_in *)out;
                if (memcmp(&in6->sin6_addr, prefix, 12) == 0) {
                        memset(out, 0, sizeof(*out));
#ifdef HAVE_SOCK_SIN_LEN
                        out4->sin_len = sizeof(*out);
#endif
                        out4->sin_family = AF_INET;
                        out4->sin_port   = in6->sin6_port;
                        memcpy(&out4->sin_addr, &in6->sin6_addr.s6_addr[12], 4);
                }
        }
#endif
}

/*
 * Register us as a server for a particular tcp connection
 */

int ctdbd_register_ips(struct ctdbd_connection *conn,
                       const struct sockaddr_storage *_server,
                       const struct sockaddr_storage *_client,
                       int (*cb)(uint32_t src_vnn, uint32_t dst_vnn,
                                 uint64_t dst_srvid,
                                 const uint8_t *msg, size_t msglen,
                                 void *private_data),
                       void *private_data)
{
        struct ctdb_connection p;
        TDB_DATA data = { .dptr = (uint8_t *)&p, .dsize = sizeof(p) };
        int ret;
        struct sockaddr_storage client;
        struct sockaddr_storage server;

        /*
         * Only one connection so far
         */

        smbd_ctdb_canonicalize_ip(_client, &client);
        smbd_ctdb_canonicalize_ip(_server, &server);

        switch (client.ss_family) {
        case AF_INET:
                memcpy(&p.dst.ip, &server, sizeof(p.dst.ip));
                memcpy(&p.src.ip, &client, sizeof(p.src.ip));
                break;
        case AF_INET6:
                memcpy(&p.dst.ip6, &server, sizeof(p.dst.ip6));
                memcpy(&p.src.ip6, &client, sizeof(p.src.ip6));
                break;
        default:
                return EIO;
        }

        /*
         * We want to be told about IP releases
         */

        ret = register_with_ctdbd(conn, CTDB_SRVID_RELEASE_IP,
                                  cb, private_data);
        if (ret != 0) {
                return ret;
        }

        /*
         * inform ctdb of our tcp connection, so if IP takeover happens ctdb
         * can send an extra ack to trigger a reset for our client, so it
         * immediately reconnects
         */
        ret = ctdbd_control(conn, CTDB_CURRENT_NODE,
                            CTDB_CONTROL_TCP_CLIENT, 0,
                            CTDB_CTRL_FLAG_NOREPLY, data, NULL, NULL,
                            NULL);
        if (ret != 0) {
                return ret;
        }
        return 0;
}

/*
  call a control on the local node
 */
int ctdbd_control_local(struct ctdbd_connection *conn, uint32_t opcode,
                        uint64_t srvid, uint32_t flags, TDB_DATA data,
                        TALLOC_CTX *mem_ctx, TDB_DATA *outdata,
                        int32_t *cstatus)
{
        return ctdbd_control(conn, CTDB_CURRENT_NODE, opcode, srvid, flags, data,
                             mem_ctx, outdata, cstatus);
}

int ctdb_watch_us(struct ctdbd_connection *conn)
{
        struct ctdb_notify_data_old reg_data;
        size_t struct_len;
        int ret;
        int32_t cstatus;

        reg_data.srvid = CTDB_SRVID_SAMBA_NOTIFY;
        reg_data.len = 1;
        reg_data.notify_data[0] = 0;

        struct_len = offsetof(struct ctdb_notify_data_old,
                              notify_data) + reg_data.len;

        ret = ctdbd_control_local(
                conn, CTDB_CONTROL_REGISTER_NOTIFY, conn->rand_srvid, 0,
                make_tdb_data((uint8_t *)&reg_data, struct_len),
                NULL, NULL, &cstatus);
        if (ret != 0) {
                DEBUG(1, ("ctdbd_control_local failed: %s\n",
                          strerror(ret)));
        }
        return ret;
}

int ctdb_unwatch(struct ctdbd_connection *conn)
{
        uint64_t srvid = CTDB_SRVID_SAMBA_NOTIFY;
        int ret;
        int32_t cstatus;

        ret = ctdbd_control_local(
                conn, CTDB_CONTROL_DEREGISTER_NOTIFY, conn->rand_srvid, 0,
                make_tdb_data((uint8_t *)&srvid, sizeof(srvid)),
                NULL, NULL, &cstatus);
        if (ret != 0) {
                DEBUG(1, ("ctdbd_control_local failed: %s\n",
                          strerror(ret)));
        }
        return ret;
}

int ctdbd_probe(const char *sockname, int timeout)
{
        /*
         * Do a very early check if ctdbd is around to avoid an abort and core
         * later
         */
        struct ctdbd_connection *conn = NULL;
        int ret;

        ret = ctdbd_init_connection(talloc_tos(), sockname, timeout,
                                    &conn);

        /*
         * We only care if we can connect.
         */
        TALLOC_FREE(conn);

        return ret;
}