/* 
   ctdb daemon code

   Copyright (C) Andrew Tridgell  2006

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "includes.h"
#include "db_wrap.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 "../include/ctdb.h"
#include "../include/ctdb_private.h"

static void ctdb_main_loop(struct ctdb_context *ctdb)
{
	ctdb->methods->start(ctdb);

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

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


static void set_non_blocking(int fd)
{
	unsigned v;
	v = fcntl(fd, F_GETFL, 0);
        fcntl(fd, F_SETFL, v | O_NONBLOCK);
}


/*
  structure describing a connected client in the daemon
 */
struct ctdb_client {
	struct ctdb_context *ctdb;
	int fd;
	struct ctdb_queue *queue;
};


/*
  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, uint32_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, len);

/*XXX cant use this since it returns an int	CTDB_NO_MEMORY(ctdb, r);*/
	talloc_set_name_const(r, "req_message packet");

	ZERO_STRUCT(*r);

	r->hdr.length    = len;
	r->hdr.ctdb_magic = CTDB_MAGIC;
	r->hdr.ctdb_version = CTDB_VERSION;
	r->hdr.operation = CTDB_REQ_MESSAGE;
	r->srvid         = srvid;
	r->datalen       = data.dsize;
	memcpy(&r->data[0], data.dptr, data.dsize);
	
	ctdb_queue_send(client->queue, (uint8_t *)&r->hdr, len);

	talloc_free(r);
	return;
}
					   

/*
  this is called when the ctdb daemon received a ctdb request to 
  set the srvid from the client
 */
static void daemon_request_register_message_handler(struct ctdb_client *client, 
						    struct ctdb_req_register *c)
{
	int res;
	res = ctdb_register_message_handler(client->ctdb, client, 
					    c->srvid, daemon_message_handler, 
					    client);
	if (res != 0) {
		printf("Failed to register handler %u in daemon\n", c->srvid);
	}
}


static struct ctdb_call_state *ctdb_fetch_lock_send(struct ctdb_db_context *ctdb_db, 
					 	    TALLOC_CTX *mem_ctx, 
						    TDB_DATA key, TDB_DATA *data)
{
	struct ctdb_call *call;
	struct ctdb_record_handle *rec;
	struct ctdb_call_state *state;

	rec = talloc(mem_ctx, struct ctdb_record_handle);
	CTDB_NO_MEMORY_NULL(ctdb_db->ctdb, rec);

	
	call = talloc(rec, struct ctdb_call);
	ZERO_STRUCT(*call);
	call->call_id = CTDB_FETCH_FUNC;
	call->key = key;
	call->flags = CTDB_IMMEDIATE_MIGRATION;


	rec->ctdb_db = ctdb_db;
	rec->key = key;
	rec->key.dptr = talloc_memdup(rec, key.dptr, key.dsize);
	rec->data = data;

	state = ctdb_call_send(ctdb_db, call);
	state->fetch_private = rec;

	return state;
}

struct client_fetch_lock_data {
	struct ctdb_client *client;
	uint32_t reqid;
};
static void daemon_fetch_lock_complete(struct ctdb_call_state *state)
{
	struct ctdb_reply_fetch_lock *r;
	struct client_fetch_lock_data *data = talloc_get_type(state->async.private_data, struct client_fetch_lock_data);
	struct ctdb_client *client = talloc_get_type(data->client, struct ctdb_client);
	int length, res;

	length = offsetof(struct ctdb_reply_fetch_lock, data) + state->call.reply_data.dsize;
	r = ctdbd_allocate_pkt(client->ctdb, length);
	if (r == NULL) {
		printf("Failed to allocate reply_call in ctdb daemon\n");
		return;
	}
	ZERO_STRUCT(*r);
	r->hdr.length       = length;
	r->hdr.ctdb_magic   = CTDB_MAGIC;
	r->hdr.ctdb_version = CTDB_VERSION;
	r->hdr.operation    = CTDB_REPLY_FETCH_LOCK;
	r->hdr.reqid        = data->reqid;
	r->state            = state->state;
	r->datalen          = state->call.reply_data.dsize;
	memcpy(&r->data[0], state->call.reply_data.dptr, r->datalen);

	res = ctdb_queue_send(client->queue, (uint8_t *)&r->hdr, r->hdr.length);
	if (res != 0) {
		printf("Failed to queue packet from daemon to client\n");
	}
	talloc_free(r);
}

/*
  called when the daemon gets a fetch lock request from a client
 */
static void daemon_request_fetch_lock(struct ctdb_client *client, 
					struct ctdb_req_fetch_lock *f)
{
	struct ctdb_call_state *state;
	TDB_DATA key, *data;
	struct ctdb_db_context *ctdb_db;
	struct client_fetch_lock_data *fl_data;

	ctdb_db = find_ctdb_db(client->ctdb, f->db_id);

	key.dsize = f->keylen;
	key.dptr = &f->key[0];

	data        = talloc(client, TDB_DATA);
	data->dptr  = NULL;
	data->dsize = 0;

	state = ctdb_fetch_lock_send(ctdb_db, client, key, data);
	talloc_steal(state, data);

	fl_data = talloc(state, struct client_fetch_lock_data);
	fl_data->client = client;
	fl_data->reqid  = f->hdr.reqid;
	state->async.fn = daemon_fetch_lock_complete;
	state->async.private_data = fl_data;
}

/*
  called when the daemon gets a store unlock request from a client

  this would never block?
 */
static void daemon_request_store_unlock(struct ctdb_client *client, 
					struct ctdb_req_store_unlock *f)
{
	struct ctdb_db_context *ctdb_db;
	struct ctdb_reply_store_unlock r;
	uint32_t caller = ctdb_get_vnn(client->ctdb);
	struct ctdb_ltdb_header header;
	TDB_DATA key, data;
	int res;

	ctdb_db = find_ctdb_db(client->ctdb, f->db_id);

	/* write the data to ltdb */
	key.dsize = f->keylen;
	key.dptr  = &f->data[0];
	res = ctdb_ltdb_fetch(ctdb_db, key, &header, NULL, NULL);
	if (res) {
		ctdb_set_error(ctdb_db->ctdb, "Fetch of locally held record failed");
		res = -1;
		goto done;
	}
	if (header.laccessor != caller) {
		header.lacount = 0;
	}
	header.laccessor = caller;
	header.lacount++;
	data.dsize = f->datalen;
	data.dptr  = &f->data[f->keylen];
	res = ctdb_ltdb_store(ctdb_db, key, &header, data);
	if ( res != 0) {
		ctdb_set_error(ctdb_db->ctdb, "ctdb_call tdb_store failed\n");
	}


done:
	/* now send the reply */
	ZERO_STRUCT(r);

	r.hdr.length     = sizeof(r);
	r.hdr.ctdb_magic = CTDB_MAGIC;
	r.hdr.ctdb_version = CTDB_VERSION;
	r.hdr.operation  = CTDB_REPLY_STORE_UNLOCK;
	r.hdr.reqid      = f->hdr.reqid;
	r.state          = res;
	
	res = ctdb_queue_send(client->queue, (uint8_t *)&r.hdr, r.hdr.length);
	if (res != 0) {
		printf("Failed to queue a store unlock response\n");
		return;
	}
}

/*
  called when the daemon gets a connect wait request from a client
 */
static void daemon_request_connect_wait(struct ctdb_client *client, 
					struct ctdb_req_connect_wait *c)
{
	struct ctdb_reply_connect_wait r;
	int res;

	/* first wait - in the daemon */
	ctdb_daemon_connect_wait(client->ctdb);

	/* now send the reply */
	ZERO_STRUCT(r);

	r.hdr.length     = sizeof(r);
	r.hdr.ctdb_magic = CTDB_MAGIC;
	r.hdr.ctdb_version = CTDB_VERSION;
	r.hdr.operation = CTDB_REPLY_CONNECT_WAIT;
	r.vnn           = ctdb_get_vnn(client->ctdb);
	r.num_connected = client->ctdb->num_connected;
	
	res = ctdb_queue_send(client->queue, (uint8_t *)&r.hdr, r.hdr.length);
	if (res != 0) {
		printf("Failed to queue a connect wait response\n");
		return;
	}
}

/*
  destroy a ctdb_client
*/
static int ctdb_client_destructor(struct ctdb_client *client)
{
	close(client->fd);
	client->fd = -1;
	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) {
		printf("Failed to send message to remote node %u\n",
		       c->hdr.destnode);
	}
}

/*
  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 ctdb_call call;
	struct ctdb_reply_call *r;
	int res;
	uint32_t length;

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

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

	state = ctdb_call_send(ctdb_db, &call);

/* XXX this must be converted to fully async */
	res = ctdb_call_recv(state, &call);
	if (res != 0) {
		printf("ctdbd_call_recv() returned error\n");
		exit(1);
	}

	length = offsetof(struct ctdb_reply_call, data) + call.reply_data.dsize;
	r = ctdbd_allocate_pkt(client->ctdb, length);
	if (r == NULL) {
		printf("Failed to allocate reply_call in ctdb daemon\n");
		return;
	}
	ZERO_STRUCT(*r);
	r->hdr.length       = length;
	r->hdr.ctdb_magic   = CTDB_MAGIC;
	r->hdr.ctdb_version = CTDB_VERSION;
	r->hdr.operation    = CTDB_REPLY_CALL;
	r->hdr.reqid        = c->hdr.reqid;
	r->datalen          = call.reply_data.dsize;
	memcpy(&r->data[0], call.reply_data.dptr, r->datalen);

	res = ctdb_queue_send(client->queue, (uint8_t *)&r, r->hdr.length);
	if (res != 0) {
		printf("Failed to queue packet from daemon to client\n");
	}
	talloc_free(r);
}


/* data contains a packet from the client */
static void client_incoming_packet(struct ctdb_client *client, void *data, size_t nread)
{
	struct ctdb_req_header *hdr = data;

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

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

	switch (hdr->operation) {
	case CTDB_REQ_CALL:
		daemon_request_call_from_client(client, (struct ctdb_req_call *)hdr);
		break;

	case CTDB_REQ_REGISTER:
		daemon_request_register_message_handler(client, 
							(struct ctdb_req_register *)hdr);
		break;
	case CTDB_REQ_MESSAGE:
		daemon_request_message_from_client(client, (struct ctdb_req_message *)hdr);
		break;

	case CTDB_REQ_CONNECT_WAIT:
		daemon_request_connect_wait(client, (struct ctdb_req_connect_wait *)hdr);
		break;
	case CTDB_REQ_FETCH_LOCK:
		daemon_request_fetch_lock(client, (struct ctdb_req_fetch_lock *)hdr);
		break;
	case CTDB_REQ_STORE_UNLOCK:
		daemon_request_store_unlock(client, (struct ctdb_req_store_unlock *)hdr);
		break;
	default:
		printf("daemon: unrecognized operation:%d\n",hdr->operation);
	}

done:
	talloc_free(data);
}


static void ctdb_client_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;
	}

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

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

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_non_blocking(fd);

	client = talloc_zero(ctdb, struct ctdb_client);
	client->ctdb = ctdb;
	client->fd = fd;

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

	talloc_set_destructor(client, ctdb_client_destructor);
}



static void ctdb_read_from_parent(struct event_context *ev, struct fd_event *fde, 
			 uint16_t flags, void *private_data)
{
	int *fd = private_data;
	int cnt;
	char buf;

	/* XXX this is a good place to try doing some cleaning up before exiting */
	cnt = read(*fd, &buf, 1);
	if (cnt==0) {
		printf("parent process exited. filedescriptor dissappeared\n");
		exit(1);
	} else {
		printf("ctdb: did not expect data from parent process\n");
		exit(1);
	}
}



/*
  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) {
		ctdb->daemon.sd = -1;
		return -1;
	}

	set_non_blocking(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) {
		close(ctdb->daemon.sd);
		ctdb->daemon.sd = -1;
		return -1;
	}	
	listen(ctdb->daemon.sd, 1);

	return 0;
}

/*
  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
*/
int ctdbd_start(struct ctdb_context *ctdb)
{
	pid_t pid;
	static int fd[2];
	int res;
	struct fd_event *fde;
	const char *domain_socket_name;

	/* generate a name to use for our local socket */
	ctdb->daemon.name = talloc_asprintf(ctdb, "%s.%s", CTDB_PATH, ctdb->address.address);
	/* 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) {
		printf("Failed to open CTDB unix domain socket\n");
		exit(10);
	}

	res = pipe(&fd[0]);
	if (res) {
		printf("Failed to open pipe for CTDB\n");
		exit(1);
	}
	pid = fork();
	if (pid==-1) {
		printf("Failed to fork CTDB daemon\n");
		exit(1);
	}

	if (pid) {
		close(fd[0]);
		close(ctdb->daemon.sd);
		ctdb->daemon.sd = -1;
		return 0;
	}

	/* 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);	
	
	close(fd[1]);
	ctdb_clear_flags(ctdb, CTDB_FLAG_DAEMON_MODE);
	ctdb->ev = event_context_init(NULL);
	fde = event_add_fd(ctdb->ev, ctdb, fd[0], EVENT_FD_READ, ctdb_read_from_parent, &fd[0]);
	fde = event_add_fd(ctdb->ev, ctdb, ctdb->daemon.sd, EVENT_FD_READ, ctdb_accept_client, ctdb);
	ctdb_main_loop(ctdb);

	return 0;
}

/*
  allocate a packet for use in client<->daemon communication
 */
void *ctdbd_allocate_pkt(struct ctdb_context *ctdb, size_t len)
{
	int size;

	size = (len+(CTDB_DS_ALIGNMENT-1)) & ~(CTDB_DS_ALIGNMENT-1);
	return talloc_size(ctdb, size);
}

int ctdb_daemon_set_message_handler(struct ctdb_context *ctdb, uint32_t srvid, 
			     ctdb_message_fn_t handler,
			     void *private_data)
{
	return ctdb_register_message_handler(ctdb, ctdb, srvid, handler, private_data);
}