Fetch the SID of the user we are running as and send with the common

[Samba/nascimento.git] / source4 / lib / messaging / messaging.c

/* 
   Unix SMB/CIFS implementation.

   Samba internal messaging functions

   Copyright (C) Andrew Tridgell 2004
   
   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/events/events.h"
#include "system/filesys.h"
#include "messaging/messaging.h"
#include "../lib/util/dlinklist.h"
#include "lib/socket/socket.h"
#include "librpc/gen_ndr/ndr_irpc.h"
#include "lib/messaging/irpc.h"
#include "tdb_wrap.h"
#include "../lib/util/unix_privs.h"
#include "librpc/rpc/dcerpc.h"
#include "../tdb/include/tdb.h"
#include "../lib/util/util_tdb.h"
#include "cluster/cluster.h"

/* change the message version with any incompatible changes in the protocol */
#define MESSAGING_VERSION 1

struct messaging_context {
        struct server_id server_id;
        struct socket_context *sock;
        const char *base_path;
        const char *path;
        struct dispatch_fn **dispatch;
        uint32_t num_types;
        struct idr_context *dispatch_tree;
        struct messaging_rec *pending;
        struct messaging_rec *retry_queue;
        struct smb_iconv_convenience *iconv_convenience;
        struct irpc_list *irpc;
        struct idr_context *idr;
        const char **names;
        struct timeval start_time;
        struct tevent_timer *retry_te;
        struct {
                struct tevent_context *ev;
                struct tevent_fd *fde;
        } event;
};

/* we have a linked list of dispatch handlers for each msg_type that
   this messaging server can deal with */
struct dispatch_fn {
        struct dispatch_fn *next, *prev;
        uint32_t msg_type;
        void *private_data;
        msg_callback_t fn;
};

/* an individual message */
struct messaging_rec {
        struct messaging_rec *next, *prev;
        struct messaging_context *msg;
        const char *path;

        struct messaging_header {
                uint32_t version;
                uint32_t msg_type;
                struct server_id from;
                struct server_id to;
                uint32_t length;
        } *header;

        DATA_BLOB packet;
        uint32_t retries;
};


static void irpc_handler(struct messaging_context *, void *, 
                         uint32_t, struct server_id, DATA_BLOB *);


/*
 A useful function for testing the message system.
*/
static void ping_message(struct messaging_context *msg, void *private_data,
                         uint32_t msg_type, struct server_id src, DATA_BLOB *data)
{
        DEBUG(1,("INFO: Received PING message from server %u.%u [%.*s]\n",
                 (unsigned int)src.node, (unsigned int)src.id, (int)data->length,
                 data->data?(const char *)data->data:""));
        messaging_send(msg, src, MSG_PONG, data);
}

/*
  return uptime of messaging server via irpc
*/
static NTSTATUS irpc_uptime(struct irpc_message *msg, 
                            struct irpc_uptime *r)
{
        struct messaging_context *ctx = talloc_get_type(msg->private_data, struct messaging_context);
        *r->out.start_time = timeval_to_nttime(&ctx->start_time);
        return NT_STATUS_OK;
}

/* 
   return the path to a messaging socket
*/
static char *messaging_path(struct messaging_context *msg, struct server_id server_id)
{
        TALLOC_CTX *tmp_ctx = talloc_new(msg);
        const char *id = cluster_id_string(tmp_ctx, server_id);
        char *s;
        if (id == NULL) {
                return NULL;
        }
        s = talloc_asprintf(msg, "%s/msg.%s", msg->base_path, id);
        talloc_steal(s, tmp_ctx);
        return s;
}

/*
  dispatch a fully received message

  note that this deliberately can match more than one message handler
  per message. That allows a single messasging context to register
  (for example) a debug handler for more than one piece of code
*/
static void messaging_dispatch(struct messaging_context *msg, struct messaging_rec *rec)
{
        struct dispatch_fn *d, *next;

        /* temporary IDs use an idtree, the rest use a array of pointers */
        if (rec->header->msg_type >= MSG_TMP_BASE) {
                d = (struct dispatch_fn *)idr_find(msg->dispatch_tree, 
                                                   rec->header->msg_type);
        } else if (rec->header->msg_type < msg->num_types) {
                d = msg->dispatch[rec->header->msg_type];
        } else {
                d = NULL;
        }

        for (; d; d = next) {
                DATA_BLOB data;
                next = d->next;
                data.data = rec->packet.data + sizeof(*rec->header);
                data.length = rec->header->length;
                d->fn(msg, d->private_data, d->msg_type, rec->header->from, &data);
        }
        rec->header->length = 0;
}

/*
  handler for messages that arrive from other nodes in the cluster
*/
static void cluster_message_handler(struct messaging_context *msg, DATA_BLOB packet)
{
        struct messaging_rec *rec;

        rec = talloc(msg, struct messaging_rec);
        if (rec == NULL) {
                smb_panic("Unable to allocate messaging_rec");
        }

        rec->msg           = msg;
        rec->path          = msg->path;
        rec->header        = (struct messaging_header *)packet.data;
        rec->packet        = packet;
        rec->retries       = 0;

        if (packet.length != sizeof(*rec->header) + rec->header->length) {
                DEBUG(0,("messaging: bad message header size %d should be %d\n", 
                         rec->header->length, (int)(packet.length - sizeof(*rec->header))));
                talloc_free(rec);
                return;
        }

        messaging_dispatch(msg, rec);
        talloc_free(rec);
}



/*
  try to send the message
*/
static NTSTATUS try_send(struct messaging_rec *rec)
{
        struct messaging_context *msg = rec->msg;
        size_t nsent;
        void *priv;
        NTSTATUS status;
        struct socket_address *path;

        /* rec->path is the path of the *other* socket, where we want
         * this to end up */
        path = socket_address_from_strings(msg, msg->sock->backend_name, 
                                           rec->path, 0);
        if (!path) {
                return NT_STATUS_NO_MEMORY;
        }

        /* we send with privileges so messages work from any context */
        priv = root_privileges();
        status = socket_sendto(msg->sock, &rec->packet, &nsent, path);
        talloc_free(path);
        talloc_free(priv);

        return status;
}

/*
  retry backed off messages
*/
static void msg_retry_timer(struct tevent_context *ev, struct tevent_timer *te, 
                            struct timeval t, void *private_data)
{
        struct messaging_context *msg = talloc_get_type(private_data,
                                                        struct messaging_context);
        msg->retry_te = NULL;

        /* put the messages back on the main queue */
        while (msg->retry_queue) {
                struct messaging_rec *rec = msg->retry_queue;
                DLIST_REMOVE(msg->retry_queue, rec);
                DLIST_ADD_END(msg->pending, rec, struct messaging_rec *);
        }

        EVENT_FD_WRITEABLE(msg->event.fde);     
}

/*
  handle a socket write event
*/
static void messaging_send_handler(struct messaging_context *msg)
{
        while (msg->pending) {
                struct messaging_rec *rec = msg->pending;
                NTSTATUS status;
                status = try_send(rec);
                if (NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
                        rec->retries++;
                        if (rec->retries > 3) {
                                /* we're getting continuous write errors -
                                   backoff this record */
                                DLIST_REMOVE(msg->pending, rec);
                                DLIST_ADD_END(msg->retry_queue, rec, 
                                              struct messaging_rec *);
                                if (msg->retry_te == NULL) {
                                        msg->retry_te = 
                                                event_add_timed(msg->event.ev, msg, 
                                                                timeval_current_ofs(1, 0), 
                                                                msg_retry_timer, msg);
                                }
                        }
                        break;
                }
                rec->retries = 0;
                if (!NT_STATUS_IS_OK(status)) {
                        TALLOC_CTX *tmp_ctx = talloc_new(msg);
                        DEBUG(1,("messaging: Lost message from %s to %s of type %u - %s\n", 
                                 cluster_id_string(tmp_ctx, rec->header->from),
                                 cluster_id_string(tmp_ctx, rec->header->to),
                                 rec->header->msg_type, 
                                 nt_errstr(status)));
                        talloc_free(tmp_ctx);
                }
                DLIST_REMOVE(msg->pending, rec);
                talloc_free(rec);
        }
        if (msg->pending == NULL) {
                EVENT_FD_NOT_WRITEABLE(msg->event.fde);
        }
}

/*
  handle a new incoming packet
*/
static void messaging_recv_handler(struct messaging_context *msg)
{
        struct messaging_rec *rec;
        NTSTATUS status;
        DATA_BLOB packet;
        size_t msize;

        /* see how many bytes are in the next packet */
        status = socket_pending(msg->sock, &msize);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(0,("socket_pending failed in messaging - %s\n", 
                         nt_errstr(status)));
                return;
        }
        
        packet = data_blob_talloc(msg, NULL, msize);
        if (packet.data == NULL) {
                /* assume this is temporary and retry */
                return;
        }
            
        status = socket_recv(msg->sock, packet.data, msize, &msize);
        if (!NT_STATUS_IS_OK(status)) {
                data_blob_free(&packet);
                return;
        }

        if (msize < sizeof(*rec->header)) {
                DEBUG(0,("messaging: bad message of size %d\n", (int)msize));
                data_blob_free(&packet);
                return;
        }

        rec = talloc(msg, struct messaging_rec);
        if (rec == NULL) {
                smb_panic("Unable to allocate messaging_rec");
        }

        talloc_steal(rec, packet.data);
        rec->msg           = msg;
        rec->path          = msg->path;
        rec->header        = (struct messaging_header *)packet.data;
        rec->packet        = packet;
        rec->retries       = 0;

        if (msize != sizeof(*rec->header) + rec->header->length) {
                DEBUG(0,("messaging: bad message header size %d should be %d\n", 
                         rec->header->length, (int)(msize - sizeof(*rec->header))));
                talloc_free(rec);
                return;
        }

        messaging_dispatch(msg, rec);
        talloc_free(rec);
}


/*
  handle a socket event
*/
static void messaging_handler(struct tevent_context *ev, struct tevent_fd *fde, 
                              uint16_t flags, void *private_data)
{
        struct messaging_context *msg = talloc_get_type(private_data,
                                                        struct messaging_context);
        if (flags & EVENT_FD_WRITE) {
                messaging_send_handler(msg);
        }
        if (flags & EVENT_FD_READ) {
                messaging_recv_handler(msg);
        }
}


/*
  Register a dispatch function for a particular message type.
*/
NTSTATUS messaging_register(struct messaging_context *msg, void *private_data,
                            uint32_t msg_type, msg_callback_t fn)
{
        struct dispatch_fn *d;

        /* possibly expand dispatch array */
        if (msg_type >= msg->num_types) {
                struct dispatch_fn **dp;
                int i;
                dp = talloc_realloc(msg, msg->dispatch, struct dispatch_fn *, msg_type+1);
                NT_STATUS_HAVE_NO_MEMORY(dp);
                msg->dispatch = dp;
                for (i=msg->num_types;i<=msg_type;i++) {
                        msg->dispatch[i] = NULL;
                }
                msg->num_types = msg_type+1;
        }

        d = talloc_zero(msg->dispatch, struct dispatch_fn);
        NT_STATUS_HAVE_NO_MEMORY(d);
        d->msg_type = msg_type;
        d->private_data = private_data;
        d->fn = fn;

        DLIST_ADD(msg->dispatch[msg_type], d);

        return NT_STATUS_OK;
}

/*
  register a temporary message handler. The msg_type is allocated
  above MSG_TMP_BASE
*/
NTSTATUS messaging_register_tmp(struct messaging_context *msg, void *private_data,
                                msg_callback_t fn, uint32_t *msg_type)
{
        struct dispatch_fn *d;
        int id;

        d = talloc_zero(msg->dispatch, struct dispatch_fn);
        NT_STATUS_HAVE_NO_MEMORY(d);
        d->private_data = private_data;
        d->fn = fn;

        id = idr_get_new_above(msg->dispatch_tree, d, MSG_TMP_BASE, UINT16_MAX);
        if (id == -1) {
                talloc_free(d);
                return NT_STATUS_TOO_MANY_CONTEXT_IDS;
        }

        d->msg_type = (uint32_t)id;
        (*msg_type) = d->msg_type;

        return NT_STATUS_OK;
}

/*
  De-register the function for a particular message type.
*/
void messaging_deregister(struct messaging_context *msg, uint32_t msg_type, void *private_data)
{
        struct dispatch_fn *d, *next;

        if (msg_type >= msg->num_types) {
                d = (struct dispatch_fn *)idr_find(msg->dispatch_tree, 
                                                   msg_type);
                if (!d) return;
                idr_remove(msg->dispatch_tree, msg_type);
                talloc_free(d);
                return;
        }

        for (d = msg->dispatch[msg_type]; d; d = next) {
                next = d->next;
                if (d->private_data == private_data) {
                        DLIST_REMOVE(msg->dispatch[msg_type], d);
                        talloc_free(d);
                }
        }
}

/*
  Send a message to a particular server
*/
NTSTATUS messaging_send(struct messaging_context *msg, struct server_id server, 
                        uint32_t msg_type, DATA_BLOB *data)
{
        struct messaging_rec *rec;
        NTSTATUS status;
        size_t dlength = data?data->length:0;

        rec = talloc(msg, struct messaging_rec);
        if (rec == NULL) {
                return NT_STATUS_NO_MEMORY;
        }

        rec->packet = data_blob_talloc(rec, NULL, sizeof(*rec->header) + dlength);
        if (rec->packet.data == NULL) {
                talloc_free(rec);
                return NT_STATUS_NO_MEMORY;
        }

        rec->retries       = 0;
        rec->msg              = msg;
        rec->header           = (struct messaging_header *)rec->packet.data;
        /* zero padding */
        ZERO_STRUCTP(rec->header);
        rec->header->version  = MESSAGING_VERSION;
        rec->header->msg_type = msg_type;
        rec->header->from     = msg->server_id;
        rec->header->to       = server;
        rec->header->length   = dlength;
        if (dlength != 0) {
                memcpy(rec->packet.data + sizeof(*rec->header), 
                       data->data, dlength);
        }

        if (!cluster_node_equal(&msg->server_id, &server)) {
                /* the destination is on another node - dispatch via
                   the cluster layer */
                status = cluster_message_send(server, &rec->packet);
                talloc_free(rec);
                return status;
        }

        rec->path = messaging_path(msg, server);
        talloc_steal(rec, rec->path);

        if (msg->pending != NULL) {
                status = STATUS_MORE_ENTRIES;
        } else {
                status = try_send(rec);
        }

        if (NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
                if (msg->pending == NULL) {
                        EVENT_FD_WRITEABLE(msg->event.fde);
                }
                DLIST_ADD_END(msg->pending, rec, struct messaging_rec *);
                return NT_STATUS_OK;
        }

        talloc_free(rec);

        return status;
}

/*
  Send a message to a particular server, with the message containing a single pointer
*/
NTSTATUS messaging_send_ptr(struct messaging_context *msg, struct server_id server, 
                            uint32_t msg_type, void *ptr)
{
        DATA_BLOB blob;

        blob.data = (uint8_t *)&ptr;
        blob.length = sizeof(void *);

        return messaging_send(msg, server, msg_type, &blob);
}


/*
  destroy the messaging context
*/
static int messaging_destructor(struct messaging_context *msg)
{
        unlink(msg->path);
        while (msg->names && msg->names[0]) {
                irpc_remove_name(msg, msg->names[0]);
        }
        return 0;
}

/*
  create the listening socket and setup the dispatcher
*/
struct messaging_context *messaging_init(TALLOC_CTX *mem_ctx, 
                                         const char *dir,
                                         struct server_id server_id, 
                                         struct smb_iconv_convenience *iconv_convenience,
                                         struct tevent_context *ev)
{
        struct messaging_context *msg;
        NTSTATUS status;
        struct socket_address *path;

        if (ev == NULL) {
                return NULL;
        }

        msg = talloc_zero(mem_ctx, struct messaging_context);
        if (msg == NULL) {
                return NULL;
        }

        /* setup a handler for messages from other cluster nodes, if appropriate */
        status = cluster_message_init(msg, server_id, cluster_message_handler);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(msg);
                return NULL;
        }

        /* create the messaging directory if needed */
        mkdir(dir, 0700);

        msg->base_path     = talloc_reference(msg, dir);
        msg->path          = messaging_path(msg, server_id);
        msg->server_id     = server_id;
        msg->iconv_convenience = iconv_convenience;
        msg->idr           = idr_init(msg);
        msg->dispatch_tree = idr_init(msg);
        msg->start_time    = timeval_current();

        status = socket_create("unix", SOCKET_TYPE_DGRAM, &msg->sock, 0);
        if (!NT_STATUS_IS_OK(status)) {
                talloc_free(msg);
                return NULL;
        }

        /* by stealing here we ensure that the socket is cleaned up (and even 
           deleted) on exit */
        talloc_steal(msg, msg->sock);

        path = socket_address_from_strings(msg, msg->sock->backend_name, 
                                           msg->path, 0);
        if (!path) {
                talloc_free(msg);
                return NULL;
        }

        status = socket_listen(msg->sock, path, 50, 0);
        if (!NT_STATUS_IS_OK(status)) {
                DEBUG(0,("Unable to setup messaging listener for '%s':%s\n", msg->path, nt_errstr(status)));
                talloc_free(msg);
                return NULL;
        }

        /* it needs to be non blocking for sends */
        set_blocking(socket_get_fd(msg->sock), false);

        msg->event.ev   = ev;
        msg->event.fde  = event_add_fd(ev, msg, socket_get_fd(msg->sock), 
                                       EVENT_FD_READ, messaging_handler, msg);
        tevent_fd_set_auto_close(msg->event.fde);

        talloc_set_destructor(msg, messaging_destructor);
        
        messaging_register(msg, NULL, MSG_PING, ping_message);
        messaging_register(msg, NULL, MSG_IRPC, irpc_handler);
        IRPC_REGISTER(msg, irpc, IRPC_UPTIME, irpc_uptime, msg);

        return msg;
}

/* 
   A hack, for the short term until we get 'client only' messaging in place 
*/
struct messaging_context *messaging_client_init(TALLOC_CTX *mem_ctx, 
                                                const char *dir,
                                                struct smb_iconv_convenience *iconv_convenience,
                                                struct tevent_context *ev)
{
        struct server_id id;
        ZERO_STRUCT(id);
        id.id = random() % 0x10000000;
        return messaging_init(mem_ctx, dir, id, iconv_convenience, ev);
}
/*
  a list of registered irpc server functions
*/
struct irpc_list {
        struct irpc_list *next, *prev;
        struct GUID uuid;
        const struct ndr_interface_table *table;
        int callnum;
        irpc_function_t fn;
        void *private_data;
};


/*
  register a irpc server function
*/
NTSTATUS irpc_register(struct messaging_context *msg_ctx, 
                       const struct ndr_interface_table *table, 
                       int callnum, irpc_function_t fn, void *private_data)
{
        struct irpc_list *irpc;

        /* override an existing handler, if any */
        for (irpc=msg_ctx->irpc; irpc; irpc=irpc->next) {
                if (irpc->table == table && irpc->callnum == callnum) {
                        break;
                }
        }
        if (irpc == NULL) {
                irpc = talloc(msg_ctx, struct irpc_list);
                NT_STATUS_HAVE_NO_MEMORY(irpc);
                DLIST_ADD(msg_ctx->irpc, irpc);
        }

        irpc->table   = table;
        irpc->callnum = callnum;
        irpc->fn      = fn;
        irpc->private_data = private_data;
        irpc->uuid = irpc->table->syntax_id.uuid;

        return NT_STATUS_OK;
}


/*
  handle an incoming irpc reply message
*/
static void irpc_handler_reply(struct messaging_context *msg_ctx, struct irpc_message *m)
{
        struct irpc_request *irpc;
        enum ndr_err_code ndr_err;

        irpc = (struct irpc_request *)idr_find(msg_ctx->idr, m->header.callid);
        if (irpc == NULL) return;

        /* parse the reply data */
        ndr_err = irpc->table->calls[irpc->callnum].ndr_pull(m->ndr, NDR_OUT, irpc->r);
        if (NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                irpc->status = m->header.status;
                talloc_steal(irpc->mem_ctx, m);
        } else {
                irpc->status = ndr_map_error2ntstatus(ndr_err);
                talloc_steal(irpc, m);
        }
        irpc->done = true;
        if (irpc->async.fn) {
                irpc->async.fn(irpc);
        }
}

/*
  send a irpc reply
*/
NTSTATUS irpc_send_reply(struct irpc_message *m, NTSTATUS status)
{
        struct ndr_push *push;
        DATA_BLOB packet;
        enum ndr_err_code ndr_err;

        m->header.status = status;

        /* setup the reply */
        push = ndr_push_init_ctx(m->ndr, m->msg_ctx->iconv_convenience);
        if (push == NULL) {
                status = NT_STATUS_NO_MEMORY;
                goto failed;
        }

        m->header.flags |= IRPC_FLAG_REPLY;

        /* construct the packet */
        ndr_err = ndr_push_irpc_header(push, NDR_SCALARS|NDR_BUFFERS, &m->header);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                status = ndr_map_error2ntstatus(ndr_err);
                goto failed;
        }

        ndr_err = m->irpc->table->calls[m->irpc->callnum].ndr_push(push, NDR_OUT, m->data);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
                status = ndr_map_error2ntstatus(ndr_err);
                goto failed;
        }

        /* send the reply message */
        packet = ndr_push_blob(push);
        status = messaging_send(m->msg_ctx, m->from, MSG_IRPC, &packet);
        if (!NT_STATUS_IS_OK(status)) goto failed;

failed:
        talloc_free(m);
        return status;
}

/*
  handle an incoming irpc request message
*/
static void irpc_handler_request(struct messaging_context *msg_ctx, 
                                 struct irpc_message *m)
{
        struct irpc_list *i;
        void *r;
        enum ndr_err_code ndr_err;

        for (i=msg_ctx->irpc; i; i=i->next) {
                if (GUID_equal(&i->uuid, &m->header.uuid) &&
                    i->table->syntax_id.if_version == m->header.if_version &&
                    i->callnum == m->header.callnum) {
                        break;
                }
        }

        if (i == NULL) {
                /* no registered handler for this message */
                talloc_free(m);
                return;
        }

        /* allocate space for the structure */
        r = talloc_zero_size(m->ndr, i->table->calls[m->header.callnum].struct_size);
        if (r == NULL) goto failed;

        /* parse the request data */
        ndr_err = i->table->calls[i->callnum].ndr_pull(m->ndr, NDR_IN, r);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) goto failed;

        /* make the call */
        m->private_data= i->private_data;
        m->defer_reply = false;
        m->msg_ctx     = msg_ctx;
        m->irpc        = i;
        m->data        = r;
        m->ev          = msg_ctx->event.ev;

        m->header.status = i->fn(m, r);

        if (m->defer_reply) {
                /* the server function has asked to defer the reply to later */
                talloc_steal(msg_ctx, m);
                return;
        }

        irpc_send_reply(m, m->header.status);
        return;

failed:
        talloc_free(m);
}

/*
  handle an incoming irpc message
*/
static void irpc_handler(struct messaging_context *msg_ctx, void *private_data,
                         uint32_t msg_type, struct server_id src, DATA_BLOB *packet)
{
        struct irpc_message *m;
        enum ndr_err_code ndr_err;

        m = talloc(msg_ctx, struct irpc_message);
        if (m == NULL) goto failed;

        m->from = src;

        m->ndr = ndr_pull_init_blob(packet, m, msg_ctx->iconv_convenience);
        if (m->ndr == NULL) goto failed;

        m->ndr->flags |= LIBNDR_FLAG_REF_ALLOC;

        ndr_err = ndr_pull_irpc_header(m->ndr, NDR_BUFFERS|NDR_SCALARS, &m->header);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) goto failed;

        if (m->header.flags & IRPC_FLAG_REPLY) {
                irpc_handler_reply(msg_ctx, m);
        } else {
                irpc_handler_request(msg_ctx, m);
        }
        return;

failed:
        talloc_free(m);
}


/*
  destroy a irpc request
*/
static int irpc_destructor(struct irpc_request *irpc)
{
        if (irpc->callid != -1) {
                idr_remove(irpc->msg_ctx->idr, irpc->callid);
                irpc->callid = -1;
        }

        if (irpc->reject_free) {
                return -1;
        }
        return 0;
}

/*
  timeout a irpc request
*/
static void irpc_timeout(struct tevent_context *ev, struct tevent_timer *te, 
                         struct timeval t, void *private_data)
{
        struct irpc_request *irpc = talloc_get_type(private_data, struct irpc_request);
        irpc->status = NT_STATUS_IO_TIMEOUT;
        irpc->done = true;
        if (irpc->async.fn) {
                irpc->async.fn(irpc);
        }
}


/*
  make a irpc call - async send
*/
struct irpc_request *irpc_call_send(struct messaging_context *msg_ctx, 
                                    struct server_id server_id, 
                                    const struct ndr_interface_table *table, 
                                    int callnum, void *r, TALLOC_CTX *ctx)
{
        struct irpc_header header;
        struct ndr_push *ndr;
        NTSTATUS status;
        DATA_BLOB packet;
        struct irpc_request *irpc;
        enum ndr_err_code ndr_err;

        irpc = talloc(msg_ctx, struct irpc_request);
        if (irpc == NULL) goto failed;

        irpc->msg_ctx  = msg_ctx;
        irpc->table    = table;
        irpc->callnum  = callnum;
        irpc->callid   = idr_get_new(msg_ctx->idr, irpc, UINT16_MAX);
        if (irpc->callid == -1) goto failed;
        irpc->r        = r;
        irpc->done     = false;
        irpc->async.fn = NULL;
        irpc->mem_ctx  = ctx;
        irpc->reject_free = false;

        talloc_set_destructor(irpc, irpc_destructor);

        /* setup the header */
        header.uuid = table->syntax_id.uuid;

        header.if_version = table->syntax_id.if_version;
        header.callid     = irpc->callid;
        header.callnum    = callnum;
        header.flags      = 0;
        header.status     = NT_STATUS_OK;

        /* construct the irpc packet */
        ndr = ndr_push_init_ctx(irpc, msg_ctx->iconv_convenience);
        if (ndr == NULL) goto failed;

        ndr_err = ndr_push_irpc_header(ndr, NDR_SCALARS|NDR_BUFFERS, &header);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) goto failed;

        ndr_err = table->calls[callnum].ndr_push(ndr, NDR_IN, r);
        if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) goto failed;

        /* and send it */
        packet = ndr_push_blob(ndr);
        status = messaging_send(msg_ctx, server_id, MSG_IRPC, &packet);
        if (!NT_STATUS_IS_OK(status)) goto failed;

        event_add_timed(msg_ctx->event.ev, irpc, 
                        timeval_current_ofs(IRPC_CALL_TIMEOUT, 0), 
                        irpc_timeout, irpc);

        talloc_free(ndr);
        return irpc;

failed:
        talloc_free(irpc);
        return NULL;
}

/*
  wait for a irpc reply
*/
NTSTATUS irpc_call_recv(struct irpc_request *irpc)
{
        NTSTATUS status;

        NT_STATUS_HAVE_NO_MEMORY(irpc);

        irpc->reject_free = true;

        while (!irpc->done) {
                if (event_loop_once(irpc->msg_ctx->event.ev) != 0) {
                        return NT_STATUS_CONNECTION_DISCONNECTED;
                }
        }

        irpc->reject_free = false;

        status = irpc->status;
        talloc_free(irpc);
        return status;
}

/*
  perform a synchronous irpc request
*/
NTSTATUS irpc_call(struct messaging_context *msg_ctx, 
                   struct server_id server_id, 
                   const struct ndr_interface_table *table, 
                   int callnum, void *r,
                   TALLOC_CTX *mem_ctx)
{
        struct irpc_request *irpc = irpc_call_send(msg_ctx, server_id, 
                                                   table, callnum, r, mem_ctx);
        return irpc_call_recv(irpc);
}

/*
  open the naming database
*/
static struct tdb_wrap *irpc_namedb_open(struct messaging_context *msg_ctx)
{
        struct tdb_wrap *t;
        char *path = talloc_asprintf(msg_ctx, "%s/names.tdb", msg_ctx->base_path);
        if (path == NULL) {
                return NULL;
        }
        t = tdb_wrap_open(msg_ctx, path, 0, 0, O_RDWR|O_CREAT, 0660);
        talloc_free(path);
        return t;
}
        

/*
  add a string name that this irpc server can be called on
*/
NTSTATUS irpc_add_name(struct messaging_context *msg_ctx, const char *name)
{
        struct tdb_wrap *t;
        TDB_DATA rec;
        int count;
        NTSTATUS status = NT_STATUS_OK;

        t = irpc_namedb_open(msg_ctx);
        NT_STATUS_HAVE_NO_MEMORY(t);

        if (tdb_lock_bystring(t->tdb, name) != 0) {
                talloc_free(t);
                return NT_STATUS_LOCK_NOT_GRANTED;
        }
        rec = tdb_fetch_bystring(t->tdb, name);
        count = rec.dsize / sizeof(struct server_id);
        rec.dptr = (unsigned char *)realloc_p(rec.dptr, struct server_id, count+1);
        rec.dsize += sizeof(struct server_id);
        if (rec.dptr == NULL) {
                tdb_unlock_bystring(t->tdb, name);
                talloc_free(t);
                return NT_STATUS_NO_MEMORY;
        }
        ((struct server_id *)rec.dptr)[count] = msg_ctx->server_id;
        if (tdb_store_bystring(t->tdb, name, rec, 0) != 0) {
                status = NT_STATUS_INTERNAL_ERROR;
        }
        free(rec.dptr);
        tdb_unlock_bystring(t->tdb, name);
        talloc_free(t);

        msg_ctx->names = str_list_add(msg_ctx->names, name);
        talloc_steal(msg_ctx, msg_ctx->names);

        return status;
}

/*
  return a list of server ids for a server name
*/
struct server_id *irpc_servers_byname(struct messaging_context *msg_ctx,
                                      TALLOC_CTX *mem_ctx,
                                      const char *name)
{
        struct tdb_wrap *t;
        TDB_DATA rec;
        int count, i;
        struct server_id *ret;

        t = irpc_namedb_open(msg_ctx);
        if (t == NULL) {
                return NULL;
        }

        if (tdb_lock_bystring(t->tdb, name) != 0) {
                talloc_free(t);
                return NULL;
        }
        rec = tdb_fetch_bystring(t->tdb, name);
        if (rec.dptr == NULL) {
                tdb_unlock_bystring(t->tdb, name);
                talloc_free(t);
                return NULL;
        }
        count = rec.dsize / sizeof(struct server_id);
        ret = talloc_array(mem_ctx, struct server_id, count+1);
        if (ret == NULL) {
                tdb_unlock_bystring(t->tdb, name);
                talloc_free(t);
                return NULL;
        }
        for (i=0;i<count;i++) {
                ret[i] = ((struct server_id *)rec.dptr)[i];
        }
        ret[i] = cluster_id(0, 0);
        free(rec.dptr);
        tdb_unlock_bystring(t->tdb, name);
        talloc_free(t);

        return ret;
}

/*
  remove a name from a messaging context
*/
void irpc_remove_name(struct messaging_context *msg_ctx, const char *name)
{
        struct tdb_wrap *t;
        TDB_DATA rec;
        int count, i;
        struct server_id *ids;

        str_list_remove(msg_ctx->names, name);

        t = irpc_namedb_open(msg_ctx);
        if (t == NULL) {
                return;
        }

        if (tdb_lock_bystring(t->tdb, name) != 0) {
                talloc_free(t);
                return;
        }
        rec = tdb_fetch_bystring(t->tdb, name);
        if (rec.dptr == NULL) {
                tdb_unlock_bystring(t->tdb, name);
                talloc_free(t);
                return;
        }
        count = rec.dsize / sizeof(struct server_id);
        if (count == 0) {
                free(rec.dptr);
                tdb_unlock_bystring(t->tdb, name);
                talloc_free(t);
                return;
        }
        ids = (struct server_id *)rec.dptr;
        for (i=0;i<count;i++) {
                if (cluster_id_equal(&ids[i], &msg_ctx->server_id)) {
                        if (i < count-1) {
                                memmove(ids+i, ids+i+1, 
                                        sizeof(struct server_id) * (count-(i+1)));
                        }
                        rec.dsize -= sizeof(struct server_id);
                        break;
                }
        }
        tdb_store_bystring(t->tdb, name, rec, 0);
        free(rec.dptr);
        tdb_unlock_bystring(t->tdb, name);
        talloc_free(t);
}

struct server_id messaging_get_server_id(struct messaging_context *msg_ctx)
{
        return msg_ctx->server_id;
}