Use a custom init function for samba4 that sets a samba4

[Samba.git] / source4 / cluster / ctdb / server / ctdb_daemon.c

/* 
   ctdb daemon code

   Copyright (C) Andrew Tridgell  2006

   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 "includes.h"
#include "lib/tdb/include/tdb.h"
#include "lib/events/events.h"
#include "lib/util/dlinklist.h"
#include "system/network.h"
#include "system/filesys.h"
#include "system/wait.h"
#include "../include/ctdb.h"
#include "../include/ctdb_private.h"

static void daemon_incoming_packet(void *, struct ctdb_req_header *);

/*
  handler for when a node changes its flags
*/
static void flag_change_handler(struct ctdb_context *ctdb, uint64_t srvid, 
                                TDB_DATA data, void *private_data)
{
        struct ctdb_node_flag_change *c = (struct ctdb_node_flag_change *)data.dptr;

        if (data.dsize != sizeof(*c) || !ctdb_validate_vnn(ctdb, c->vnn)) {
                DEBUG(0,(__location__ "Invalid data in ctdb_node_flag_change\n"));
                return;
        }

        if (!ctdb_validate_vnn(ctdb, c->vnn)) {
                DEBUG(0,("Bad vnn %u in flag_change_handler\n", c->vnn));
                return;
        }

        /* don't get the disconnected flag from the other node */
        ctdb->nodes[c->vnn]->flags = 
                (ctdb->nodes[c->vnn]->flags&NODE_FLAGS_DISCONNECTED) 
                | (c->flags & ~NODE_FLAGS_DISCONNECTED);        
        DEBUG(2,("Node flags for node %u are now 0x%x\n", c->vnn, ctdb->nodes[c->vnn]->flags));

        /* make sure we don't hold any IPs when we shouldn't */
        if (c->vnn == ctdb->vnn &&
            (ctdb->nodes[c->vnn]->flags & (NODE_FLAGS_INACTIVE|NODE_FLAGS_BANNED))) {
                ctdb_release_all_ips(ctdb);
        }
}

/* called when the "startup" event script has finished */
static void ctdb_start_transport(struct ctdb_context *ctdb, int status, void *p)
{
        if (status != 0) {
                DEBUG(0,("startup event failed!\n"));
                ctdb_fatal(ctdb, "startup event script failed");                
        }

        /* start the transport running */
        if (ctdb->methods->start(ctdb) != 0) {
                DEBUG(0,("transport failed to start!\n"));
                ctdb_fatal(ctdb, "transport failed to start");
        }

        /* start the recovery daemon process */
        if (ctdb_start_recoverd(ctdb) != 0) {
                DEBUG(0,("Failed to start recovery daemon\n"));
                exit(11);
        }

        /* a handler for when nodes are disabled/enabled */
        ctdb_register_message_handler(ctdb, ctdb, CTDB_SRVID_NODE_FLAGS_CHANGED, 
                                      flag_change_handler, NULL);

        /* start monitoring for dead nodes */
        ctdb_start_monitoring(ctdb);
}

/* go into main ctdb loop */
static void ctdb_main_loop(struct ctdb_context *ctdb)
{
        int ret = -1;

        if (strcmp(ctdb->transport, "tcp") == 0) {
                int ctdb_tcp_init(struct ctdb_context *);
                ret = ctdb_tcp_init(ctdb);
        }
#ifdef USE_INFINIBAND
        if (strcmp(ctdb->transport, "ib") == 0) {
                int ctdb_ibw_init(struct ctdb_context *);
                ret = ctdb_ibw_init(ctdb);
        }
#endif
        if (ret != 0) {
                DEBUG(0,("Failed to initialise transport '%s'\n", ctdb->transport));
                return;
        }

        /* initialise the transport  */
        if (ctdb->methods->initialise(ctdb) != 0) {
                DEBUG(0,("transport failed to initialise!\n"));
                ctdb_fatal(ctdb, "transport failed to initialise");
        }

        /* tell all other nodes we've just started up */
        ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_ALL,
                                 0, CTDB_CONTROL_STARTUP, 0,
                                 CTDB_CTRL_FLAG_NOREPLY,
                                 tdb_null, NULL, NULL);

        /* release any IPs we hold from previous runs of the daemon */
        ctdb_release_all_ips(ctdb);

        ret = ctdb_event_script_callback(ctdb, timeval_zero(), ctdb, 
                                         ctdb_start_transport, NULL, "startup");
        if (ret != 0) {
                DEBUG(0,("Failed startup event script\n"));
                return;
        }

        /* go into a wait loop to allow other nodes to complete */
        event_loop_wait(ctdb->ev);

        DEBUG(0,("event_loop_wait() returned. this should not happen\n"));
        exit(1);
}


static void block_signal(int signum)
{
        struct sigaction act;

        memset(&act, 0, sizeof(act));

        act.sa_handler = SIG_IGN;
        sigemptyset(&act.sa_mask);
        sigaddset(&act.sa_mask, signum);
        sigaction(signum, &act, NULL);
}


/*
  send a packet to a client
 */
static int daemon_queue_send(struct ctdb_client *client, struct ctdb_req_header *hdr)
{
        client->ctdb->statistics.client_packets_sent++;
        return ctdb_queue_send(client->queue, (uint8_t *)hdr, hdr->length);
}

/*
  message handler for when we are in daemon mode. This redirects the message
  to the right client
 */
static void daemon_message_handler(struct ctdb_context *ctdb, uint64_t srvid, 
                                    TDB_DATA data, void *private_data)
{
        struct ctdb_client *client = talloc_get_type(private_data, struct ctdb_client);
        struct ctdb_req_message *r;
        int len;

        /* construct a message to send to the client containing the data */
        len = offsetof(struct ctdb_req_message, data) + data.dsize;
        r = ctdbd_allocate_pkt(ctdb, ctdb, CTDB_REQ_MESSAGE, 
                               len, struct ctdb_req_message);
        CTDB_NO_MEMORY_VOID(ctdb, r);

        talloc_set_name_const(r, "req_message packet");

        r->srvid         = srvid;
        r->datalen       = data.dsize;
        memcpy(&r->data[0], data.dptr, data.dsize);

        daemon_queue_send(client, &r->hdr);

        talloc_free(r);
}
                                           

/*
  this is called when the ctdb daemon received a ctdb request to 
  set the srvid from the client
 */
int daemon_register_message_handler(struct ctdb_context *ctdb, uint32_t client_id, uint64_t srvid)
{
        struct ctdb_client *client = ctdb_reqid_find(ctdb, client_id, struct ctdb_client);
        int res;
        if (client == NULL) {
                DEBUG(0,("Bad client_id in daemon_request_register_message_handler\n"));
                return -1;
        }
        res = ctdb_register_message_handler(ctdb, client, srvid, daemon_message_handler, client);
        if (res != 0) {
                DEBUG(0,(__location__ " Failed to register handler %llu in daemon\n", 
                         (unsigned long long)srvid));
        } else {
                DEBUG(2,(__location__ " Registered message handler for srvid=%llu\n", 
                         (unsigned long long)srvid));
        }

        /* this is a hack for Samba - we now know the pid of the Samba client */
        if ((srvid & 0xFFFFFFFF) == srvid &&
            kill(srvid, 0) == 0) {
                client->pid = srvid;
                DEBUG(0,(__location__ " Registered PID %u for client %u\n",
                         (unsigned)client->pid, client_id));
        }
        return res;
}

/*
  this is called when the ctdb daemon received a ctdb request to 
  remove a srvid from the client
 */
int daemon_deregister_message_handler(struct ctdb_context *ctdb, uint32_t client_id, uint64_t srvid)
{
        struct ctdb_client *client = ctdb_reqid_find(ctdb, client_id, struct ctdb_client);
        if (client == NULL) {
                DEBUG(0,("Bad client_id in daemon_request_deregister_message_handler\n"));
                return -1;
        }
        return ctdb_deregister_message_handler(ctdb, srvid, client);
}


/*
  destroy a ctdb_client
*/
static int ctdb_client_destructor(struct ctdb_client *client)
{
        ctdb_takeover_client_destructor_hook(client);
        ctdb_reqid_remove(client->ctdb, client->client_id);
        client->ctdb->statistics.num_clients--;
        return 0;
}


/*
  this is called when the ctdb daemon received a ctdb request message
  from a local client over the unix domain socket
 */
static void daemon_request_message_from_client(struct ctdb_client *client, 
                                               struct ctdb_req_message *c)
{
        TDB_DATA data;
        int res;

        /* maybe the message is for another client on this node */
        if (ctdb_get_vnn(client->ctdb)==c->hdr.destnode) {
                ctdb_request_message(client->ctdb, (struct ctdb_req_header *)c);
                return;
        }

        /* its for a remote node */
        data.dptr = &c->data[0];
        data.dsize = c->datalen;
        res = ctdb_daemon_send_message(client->ctdb, c->hdr.destnode,
                                       c->srvid, data);
        if (res != 0) {
                DEBUG(0,(__location__ " Failed to send message to remote node %u\n",
                         c->hdr.destnode));
        }
}


struct daemon_call_state {
        struct ctdb_client *client;
        uint32_t reqid;
        struct ctdb_call *call;
        struct timeval start_time;
};

/* 
   complete a call from a client 
*/
static void daemon_call_from_client_callback(struct ctdb_call_state *state)
{
        struct daemon_call_state *dstate = talloc_get_type(state->async.private_data, 
                                                           struct daemon_call_state);
        struct ctdb_reply_call *r;
        int res;
        uint32_t length;
        struct ctdb_client *client = dstate->client;

        talloc_steal(client, dstate);
        talloc_steal(dstate, dstate->call);

        res = ctdb_daemon_call_recv(state, dstate->call);
        if (res != 0) {
                DEBUG(0, (__location__ " ctdbd_call_recv() returned error\n"));
                client->ctdb->statistics.pending_calls--;
                ctdb_latency(&client->ctdb->statistics.max_call_latency, dstate->start_time);
                return;
        }

        length = offsetof(struct ctdb_reply_call, data) + dstate->call->reply_data.dsize;
        r = ctdbd_allocate_pkt(client->ctdb, dstate, CTDB_REPLY_CALL, 
                               length, struct ctdb_reply_call);
        if (r == NULL) {
                DEBUG(0, (__location__ " Failed to allocate reply_call in ctdb daemon\n"));
                client->ctdb->statistics.pending_calls--;
                ctdb_latency(&client->ctdb->statistics.max_call_latency, dstate->start_time);
                return;
        }
        r->hdr.reqid        = dstate->reqid;
        r->datalen          = dstate->call->reply_data.dsize;
        memcpy(&r->data[0], dstate->call->reply_data.dptr, r->datalen);

        res = daemon_queue_send(client, &r->hdr);
        if (res != 0) {
                DEBUG(0, (__location__ " Failed to queue packet from daemon to client\n"));
        }
        ctdb_latency(&client->ctdb->statistics.max_call_latency, dstate->start_time);
        talloc_free(dstate);
        client->ctdb->statistics.pending_calls--;
}


static void daemon_request_call_from_client(struct ctdb_client *client, 
                                            struct ctdb_req_call *c);

/*
  this is called when the ctdb daemon received a ctdb request call
  from a local client over the unix domain socket
 */
static void daemon_request_call_from_client(struct ctdb_client *client, 
                                            struct ctdb_req_call *c)
{
        struct ctdb_call_state *state;
        struct ctdb_db_context *ctdb_db;
        struct daemon_call_state *dstate;
        struct ctdb_call *call;
        struct ctdb_ltdb_header header;
        TDB_DATA key, data;
        int ret;
        struct ctdb_context *ctdb = client->ctdb;

        ctdb->statistics.total_calls++;
        ctdb->statistics.pending_calls++;

        ctdb_db = find_ctdb_db(client->ctdb, c->db_id);
        if (!ctdb_db) {
                DEBUG(0, (__location__ " Unknown database in request. db_id==0x%08x",
                          c->db_id));
                ctdb->statistics.pending_calls--;
                return;
        }

        key.dptr = c->data;
        key.dsize = c->keylen;

        ret = ctdb_ltdb_lock_fetch_requeue(ctdb_db, key, &header, 
                                           (struct ctdb_req_header *)c, &data,
                                           daemon_incoming_packet, client, True);
        if (ret == -2) {
                /* will retry later */
                ctdb->statistics.pending_calls--;
                return;
        }

        if (ret != 0) {
                DEBUG(0,(__location__ " Unable to fetch record\n"));
                ctdb->statistics.pending_calls--;
                return;
        }

        dstate = talloc(client, struct daemon_call_state);
        if (dstate == NULL) {
                ctdb_ltdb_unlock(ctdb_db, key);
                DEBUG(0,(__location__ " Unable to allocate dstate\n"));
                ctdb->statistics.pending_calls--;
                return;
        }
        dstate->start_time = timeval_current();
        dstate->client = client;
        dstate->reqid  = c->hdr.reqid;
        talloc_steal(dstate, data.dptr);

        call = dstate->call = talloc_zero(dstate, struct ctdb_call);
        if (call == NULL) {
                ctdb_ltdb_unlock(ctdb_db, key);
                DEBUG(0,(__location__ " Unable to allocate call\n"));
                ctdb->statistics.pending_calls--;
                ctdb_latency(&ctdb->statistics.max_call_latency, dstate->start_time);
                return;
        }

        call->call_id = c->callid;
        call->key = key;
        call->call_data.dptr = c->data + c->keylen;
        call->call_data.dsize = c->calldatalen;
        call->flags = c->flags;

        if (header.dmaster == ctdb->vnn) {
                state = ctdb_call_local_send(ctdb_db, call, &header, &data);
        } else {
                state = ctdb_daemon_call_send_remote(ctdb_db, call, &header);
        }

        ctdb_ltdb_unlock(ctdb_db, key);

        if (state == NULL) {
                DEBUG(0,(__location__ " Unable to setup call send\n"));
                ctdb->statistics.pending_calls--;
                ctdb_latency(&ctdb->statistics.max_call_latency, dstate->start_time);
                return;
        }
        talloc_steal(state, dstate);
        talloc_steal(client, state);

        state->async.fn = daemon_call_from_client_callback;
        state->async.private_data = dstate;
}


static void daemon_request_control_from_client(struct ctdb_client *client, 
                                               struct ctdb_req_control *c);

/* data contains a packet from the client */
static void daemon_incoming_packet(void *p, struct ctdb_req_header *hdr)
{
        struct ctdb_client *client = talloc_get_type(p, struct ctdb_client);
        TALLOC_CTX *tmp_ctx;
        struct ctdb_context *ctdb = client->ctdb;

        /* place the packet as a child of a tmp_ctx. We then use
           talloc_free() below to free it. If any of the calls want
           to keep it, then they will steal it somewhere else, and the
           talloc_free() will be a no-op */
        tmp_ctx = talloc_new(client);
        talloc_steal(tmp_ctx, hdr);

        if (hdr->ctdb_magic != CTDB_MAGIC) {
                ctdb_set_error(client->ctdb, "Non CTDB packet rejected in daemon\n");
                goto done;
        }

        if (hdr->ctdb_version != CTDB_VERSION) {
                ctdb_set_error(client->ctdb, "Bad CTDB version 0x%x rejected in daemon\n", hdr->ctdb_version);
                goto done;
        }

        switch (hdr->operation) {
        case CTDB_REQ_CALL:
                ctdb->statistics.client.req_call++;
                daemon_request_call_from_client(client, (struct ctdb_req_call *)hdr);
                break;

        case CTDB_REQ_MESSAGE:
                ctdb->statistics.client.req_message++;
                daemon_request_message_from_client(client, (struct ctdb_req_message *)hdr);
                break;

        case CTDB_REQ_CONTROL:
                ctdb->statistics.client.req_control++;
                daemon_request_control_from_client(client, (struct ctdb_req_control *)hdr);
                break;

        default:
                DEBUG(0,(__location__ " daemon: unrecognized operation %u\n",
                         hdr->operation));
        }

done:
        talloc_free(tmp_ctx);
}

/*
  called when the daemon gets a incoming packet
 */
static void ctdb_daemon_read_cb(uint8_t *data, size_t cnt, void *args)
{
        struct ctdb_client *client = talloc_get_type(args, struct ctdb_client);
        struct ctdb_req_header *hdr;

        if (cnt == 0) {
                talloc_free(client);
                return;
        }

        client->ctdb->statistics.client_packets_recv++;

        if (cnt < sizeof(*hdr)) {
                ctdb_set_error(client->ctdb, "Bad packet length %u in daemon\n", 
                               (unsigned)cnt);
                return;
        }
        hdr = (struct ctdb_req_header *)data;
        if (cnt != hdr->length) {
                ctdb_set_error(client->ctdb, "Bad header length %u expected %u\n in daemon", 
                               (unsigned)hdr->length, (unsigned)cnt);
                return;
        }

        if (hdr->ctdb_magic != CTDB_MAGIC) {
                ctdb_set_error(client->ctdb, "Non CTDB packet rejected\n");
                return;
        }

        if (hdr->ctdb_version != CTDB_VERSION) {
                ctdb_set_error(client->ctdb, "Bad CTDB version 0x%x rejected in daemon\n", hdr->ctdb_version);
                return;
        }

        DEBUG(3,(__location__ " client request %u of type %u length %u from "
                 "node %u to %u\n", hdr->reqid, hdr->operation, hdr->length,
                 hdr->srcnode, hdr->destnode));

        /* it is the responsibility of the incoming packet function to free 'data' */
        daemon_incoming_packet(client, hdr);
}

static void ctdb_accept_client(struct event_context *ev, struct fd_event *fde, 
                         uint16_t flags, void *private_data)
{
        struct sockaddr_in addr;
        socklen_t len;
        int fd;
        struct ctdb_context *ctdb = talloc_get_type(private_data, struct ctdb_context);
        struct ctdb_client *client;

        memset(&addr, 0, sizeof(addr));
        len = sizeof(addr);
        fd = accept(ctdb->daemon.sd, (struct sockaddr *)&addr, &len);
        if (fd == -1) {
                return;
        }

        set_nonblocking(fd);
        set_close_on_exec(fd);

        client = talloc_zero(ctdb, struct ctdb_client);
        client->ctdb = ctdb;
        client->fd = fd;
        client->client_id = ctdb_reqid_new(ctdb, client);
        ctdb->statistics.num_clients++;

        client->queue = ctdb_queue_setup(ctdb, client, fd, CTDB_DS_ALIGNMENT, 
                                         ctdb_daemon_read_cb, client);

        talloc_set_destructor(client, ctdb_client_destructor);
}



/*
  create a unix domain socket and bind it
  return a file descriptor open on the socket 
*/
static int ux_socket_bind(struct ctdb_context *ctdb)
{
        struct sockaddr_un addr;

        ctdb->daemon.sd = socket(AF_UNIX, SOCK_STREAM, 0);
        if (ctdb->daemon.sd == -1) {
                return -1;
        }

        set_nonblocking(ctdb->daemon.sd);
        set_close_on_exec(ctdb->daemon.sd);

#if 0
        /* AIX doesn't like this :( */
        if (fchown(ctdb->daemon.sd, geteuid(), getegid()) != 0 ||
            fchmod(ctdb->daemon.sd, 0700) != 0) {
                DEBUG(0,("Unable to secure ctdb socket '%s', ctdb->daemon.name\n"));
                goto failed;
        }
#endif

        set_nonblocking(ctdb->daemon.sd);

        memset(&addr, 0, sizeof(addr));
        addr.sun_family = AF_UNIX;
        strncpy(addr.sun_path, ctdb->daemon.name, sizeof(addr.sun_path));

        if (bind(ctdb->daemon.sd, (struct sockaddr *)&addr, sizeof(addr)) == -1) {
                DEBUG(0,("Unable to bind on ctdb socket '%s'\n", ctdb->daemon.name));
                goto failed;
        }       
        if (listen(ctdb->daemon.sd, 10) != 0) {
                DEBUG(0,("Unable to listen on ctdb socket '%s'\n", ctdb->daemon.name));
                goto failed;
        }

        return 0;

failed:
        close(ctdb->daemon.sd);
        ctdb->daemon.sd = -1;
        return -1;      
}

/*
  delete the socket on exit - called on destruction of autofree context
 */
static int unlink_destructor(const char *name)
{
        unlink(name);
        return 0;
}


/*
  start the protocol going as a daemon
*/
int ctdb_start_daemon(struct ctdb_context *ctdb, bool do_fork)
{
        int res;
        struct fd_event *fde;
        const char *domain_socket_name;

        /* get rid of any old sockets */
        unlink(ctdb->daemon.name);

        /* create a unix domain stream socket to listen to */
        res = ux_socket_bind(ctdb);
        if (res!=0) {
                DEBUG(0,(__location__ " Failed to open CTDB unix domain socket\n"));
                exit(10);
        }

        if (do_fork && fork()) {
                return 0;
        }

        tdb_reopen_all(False);

        if (do_fork) {
                setsid();
        }
        block_signal(SIGPIPE);

        /* try to set us up as realtime */
        ctdb_set_realtime(true);

        /* ensure the socket is deleted on exit of the daemon */
        domain_socket_name = talloc_strdup(talloc_autofree_context(), ctdb->daemon.name);
        talloc_set_destructor(domain_socket_name, unlink_destructor);   

        ctdb->ev = s4_event_context_init(NULL);

        /* start frozen, then let the first election sort things out */
        if (!ctdb_blocking_freeze(ctdb)) {
                DEBUG(0,("Failed to get initial freeze\n"));
                exit(12);
        }

        /* force initial recovery for election */
        ctdb->recovery_mode = CTDB_RECOVERY_ACTIVE;

        /* now start accepting clients, only can do this once frozen */
        fde = event_add_fd(ctdb->ev, ctdb, ctdb->daemon.sd, 
                           EVENT_FD_READ|EVENT_FD_AUTOCLOSE, 
                           ctdb_accept_client, ctdb);

        ctdb_main_loop(ctdb);

        return 0;
}

/*
  allocate a packet for use in daemon<->daemon communication
 */
struct ctdb_req_header *_ctdb_transport_allocate(struct ctdb_context *ctdb,
                                                 TALLOC_CTX *mem_ctx, 
                                                 enum ctdb_operation operation, 
                                                 size_t length, size_t slength,
                                                 const char *type)
{
        int size;
        struct ctdb_req_header *hdr;

        length = MAX(length, slength);
        size = (length+(CTDB_DS_ALIGNMENT-1)) & ~(CTDB_DS_ALIGNMENT-1);

        hdr = (struct ctdb_req_header *)ctdb->methods->allocate_pkt(mem_ctx, size);
        if (hdr == NULL) {
                DEBUG(0,("Unable to allocate transport packet for operation %u of length %u\n",
                         operation, (unsigned)length));
                return NULL;
        }
        talloc_set_name_const(hdr, type);
        memset(hdr, 0, slength);
        hdr->length       = length;
        hdr->operation    = operation;
        hdr->ctdb_magic   = CTDB_MAGIC;
        hdr->ctdb_version = CTDB_VERSION;
        hdr->generation   = ctdb->vnn_map->generation;
        hdr->srcnode      = ctdb->vnn;

        return hdr;     
}

struct daemon_control_state {
        struct daemon_control_state *next, *prev;
        struct ctdb_client *client;
        struct ctdb_req_control *c;
        uint32_t reqid;
        struct ctdb_node *node;
};

/*
  callback when a control reply comes in
 */
static void daemon_control_callback(struct ctdb_context *ctdb,
                                    int32_t status, TDB_DATA data, 
                                    const char *errormsg,
                                    void *private_data)
{
        struct daemon_control_state *state = talloc_get_type(private_data, 
                                                             struct daemon_control_state);
        struct ctdb_client *client = state->client;
        struct ctdb_reply_control *r;
        size_t len;

        /* construct a message to send to the client containing the data */
        len = offsetof(struct ctdb_reply_control, data) + data.dsize;
        if (errormsg) {
                len += strlen(errormsg);
        }
        r = ctdbd_allocate_pkt(ctdb, state, CTDB_REPLY_CONTROL, len, 
                               struct ctdb_reply_control);
        CTDB_NO_MEMORY_VOID(ctdb, r);

        r->hdr.reqid     = state->reqid;
        r->status        = status;
        r->datalen       = data.dsize;
        r->errorlen = 0;
        memcpy(&r->data[0], data.dptr, data.dsize);
        if (errormsg) {
                r->errorlen = strlen(errormsg);
                memcpy(&r->data[r->datalen], errormsg, r->errorlen);
        }

        daemon_queue_send(client, &r->hdr);

        talloc_free(state);
}

/*
  fail all pending controls to a disconnected node
 */
void ctdb_daemon_cancel_controls(struct ctdb_context *ctdb, struct ctdb_node *node)
{
        struct daemon_control_state *state;
        while ((state = node->pending_controls)) {
                DLIST_REMOVE(node->pending_controls, state);
                daemon_control_callback(ctdb, (uint32_t)-1, tdb_null, 
                                        "node is disconnected", state);
        }
}

/*
  destroy a daemon_control_state
 */
static int daemon_control_destructor(struct daemon_control_state *state)
{
        if (state->node) {
                DLIST_REMOVE(state->node->pending_controls, state);
        }
        return 0;
}

/*
  this is called when the ctdb daemon received a ctdb request control
  from a local client over the unix domain socket
 */
static void daemon_request_control_from_client(struct ctdb_client *client, 
                                               struct ctdb_req_control *c)
{
        TDB_DATA data;
        int res;
        struct daemon_control_state *state;
        TALLOC_CTX *tmp_ctx = talloc_new(client);

        if (c->hdr.destnode == CTDB_CURRENT_NODE) {
                c->hdr.destnode = client->ctdb->vnn;
        }

        state = talloc(client, struct daemon_control_state);
        CTDB_NO_MEMORY_VOID(client->ctdb, state);

        state->client = client;
        state->c = talloc_steal(state, c);
        state->reqid = c->hdr.reqid;
        if (ctdb_validate_vnn(client->ctdb, c->hdr.destnode)) {
                state->node = client->ctdb->nodes[c->hdr.destnode];
                DLIST_ADD(state->node->pending_controls, state);
        } else {
                state->node = NULL;
        }

        talloc_set_destructor(state, daemon_control_destructor);

        if (c->flags & CTDB_CTRL_FLAG_NOREPLY) {
                talloc_steal(tmp_ctx, state);
        }
        
        data.dptr = &c->data[0];
        data.dsize = c->datalen;
        res = ctdb_daemon_send_control(client->ctdb, c->hdr.destnode,
                                       c->srvid, c->opcode, client->client_id,
                                       c->flags,
                                       data, daemon_control_callback,
                                       state);
        if (res != 0) {
                DEBUG(0,(__location__ " Failed to send control to remote node %u\n",
                         c->hdr.destnode));
        }

        talloc_free(tmp_ctx);
}

/*
  register a call function
*/
int ctdb_daemon_set_call(struct ctdb_context *ctdb, uint32_t db_id,
                         ctdb_fn_t fn, int id)
{
        struct ctdb_registered_call *call;
        struct ctdb_db_context *ctdb_db;

        ctdb_db = find_ctdb_db(ctdb, db_id);
        if (ctdb_db == NULL) {
                return -1;
        }

        call = talloc(ctdb_db, struct ctdb_registered_call);
        call->fn = fn;
        call->id = id;

        DLIST_ADD(ctdb_db->calls, call);        
        return 0;
}



/*
  this local messaging handler is ugly, but is needed to prevent
  recursion in ctdb_send_message() when the destination node is the
  same as the source node
 */
struct ctdb_local_message {
        struct ctdb_context *ctdb;
        uint64_t srvid;
        TDB_DATA data;
};

static void ctdb_local_message_trigger(struct event_context *ev, struct timed_event *te, 
                                       struct timeval t, void *private_data)
{
        struct ctdb_local_message *m = talloc_get_type(private_data, 
                                                       struct ctdb_local_message);
        int res;

        res = ctdb_dispatch_message(m->ctdb, m->srvid, m->data);
        if (res != 0) {
                DEBUG(0, (__location__ " Failed to dispatch message for srvid=%llu\n", 
                          (unsigned long long)m->srvid));
        }
        talloc_free(m);
}

static int ctdb_local_message(struct ctdb_context *ctdb, uint64_t srvid, TDB_DATA data)
{
        struct ctdb_local_message *m;
        m = talloc(ctdb, struct ctdb_local_message);
        CTDB_NO_MEMORY(ctdb, m);

        m->ctdb = ctdb;
        m->srvid = srvid;
        m->data  = data;
        m->data.dptr = talloc_memdup(m, m->data.dptr, m->data.dsize);
        if (m->data.dptr == NULL) {
                talloc_free(m);
                return -1;
        }

        /* this needs to be done as an event to prevent recursion */
        event_add_timed(ctdb->ev, m, timeval_zero(), ctdb_local_message_trigger, m);
        return 0;
}

/*
  send a ctdb message
*/
int ctdb_daemon_send_message(struct ctdb_context *ctdb, uint32_t vnn,
                             uint64_t srvid, TDB_DATA data)
{
        struct ctdb_req_message *r;
        int len;

        /* see if this is a message to ourselves */
        if (vnn == ctdb->vnn) {
                return ctdb_local_message(ctdb, srvid, data);
        }

        len = offsetof(struct ctdb_req_message, data) + data.dsize;
        r = ctdb_transport_allocate(ctdb, ctdb, CTDB_REQ_MESSAGE, len,
                                    struct ctdb_req_message);
        CTDB_NO_MEMORY(ctdb, r);

        r->hdr.destnode  = vnn;
        r->srvid         = srvid;
        r->datalen       = data.dsize;
        memcpy(&r->data[0], data.dptr, data.dsize);

        ctdb_queue_packet(ctdb, &r->hdr);

        talloc_free(r);
        return 0;
}