messaging.c

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/* 
   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 "lib/tdb/include/tdb.h"
#include "lib/util/util_tdb.h"
#include "lib/util/util_tdb.h"
#include "cluster/cluster.h"
#include "param/param.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 timed_event *retry_te;
	struct {
		struct event_context *ev;
		struct fd_event *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;
	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, 
			 uint32_t msg_type, struct server_id src, DATA_BLOB *data)
{
	DEBUG(1,("INFO: Received PING message from server %u.%u [%.*s]\n",
		 (uint_t)src.node, (uint_t)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, 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)
{
	return talloc_asprintf(msg, "%s/msg.%s", msg->base_path, 
			       cluster_id_string(msg, server_id));
}

/*
  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, 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 event_context *ev, struct timed_event *te, 
			    struct timeval t, void *private)
{
	struct messaging_context *msg = talloc_get_type(private, 
							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)) {
			DEBUG(1,("messaging: Lost message from %s to %s of type %u - %s\n", 
				 cluster_id_string(debug_ctx(), rec->header->from), 
				 cluster_id_string(debug_ctx(), rec->header->to), 
				 rec->header->msg_type, 
				 nt_errstr(status)));
		}
		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 event_context *ev, struct fd_event *fde, 
			      uint16_t flags, void *private)
{
	struct messaging_context *msg = talloc_get_type(private, 
							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,
			    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 = private;
	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,
				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 = private;
	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)
{
	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 == private) {
			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 event_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;
	}