/*
   Unix SMB/CIFS implementation.
   change notify handling
   Copyright (C) Andrew Tridgell 2000
   Copyright (C) Jeremy Allison 1994-1998

   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 2 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, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "includes.h"

static struct cnotify_fns *cnotify;

/****************************************************************************
 This is the structure to queue to implement NT change
 notify. It consists of smb_size bytes stored from the
 transact command (to keep the mid, tid etc around).
 Plus the fid to examine and notify private data.
*****************************************************************************/

struct change_notify {
	struct change_notify *next, *prev;
	files_struct *fsp;
	uint32 flags;
	uint32 max_param_count;
	char request_buf[smb_size];
	void *change_data;
};

static struct change_notify *change_notify_list;

static BOOL notify_marshall_changes(struct notify_changes *changes,
				    prs_struct *ps)
{
	int i;
	UNISTR uni_name;

	for (i=0; i<changes->num_changes; i++) {
		struct notify_change *c = &changes->changes[i];
		size_t namelen;
		uint32 u32_tmp;	/* Temp arg to prs_uint32 to avoid
				 * signed/unsigned issues */

		namelen = convert_string_allocate(
			NULL, CH_UNIX, CH_UTF16LE, c->name, strlen(c->name)+1,
			&uni_name.buffer, True);
		if ((namelen == -1) || (uni_name.buffer == NULL)) {
			goto fail;
		}

		namelen -= 2;	/* Dump NULL termination */

		/*
		 * Offset to next entry, only if there is one
		 */

		u32_tmp = (i == changes->num_changes-1) ? 0 : namelen + 12;
		if (!prs_uint32("offset", ps, 1, &u32_tmp)) goto fail;

		u32_tmp = c->action;
		if (!prs_uint32("action", ps, 1, &u32_tmp)) goto fail;

		u32_tmp = namelen;
		if (!prs_uint32("namelen", ps, 1, &u32_tmp)) goto fail;

		if (!prs_unistr("name", ps, 1, &uni_name)) goto fail;

		/*
		 * Not NULL terminated, decrease by the 2 UCS2 \0 chars
		 */
		prs_set_offset(ps, prs_offset(ps)-2);

		SAFE_FREE(uni_name.buffer);
	}

	return True;

 fail:
	SAFE_FREE(uni_name.buffer);
	return False;
}

/****************************************************************************
 Setup the common parts of the return packet and send it.
*****************************************************************************/

static void change_notify_reply_packet(const char *request_buf,
				       NTSTATUS error_code)
{
	char outbuf[smb_size+38];

	memset(outbuf, '\0', sizeof(outbuf));
	construct_reply_common(request_buf, outbuf);

	ERROR_NT(error_code);

	/*
	 * Seems NT needs a transact command with an error code
	 * in it. This is a longer packet than a simple error.
	 */
	set_message(outbuf,18,0,False);

	show_msg(outbuf);
	if (!send_smb(smbd_server_fd(),outbuf))
		exit_server_cleanly("change_notify_reply_packet: send_smb failed.");
}

void change_notify_reply(const char *request_buf, uint32 max_param_count,
			 files_struct *fsp)
{
	char *outbuf = NULL;
	prs_struct ps;
	size_t buflen = smb_size+38+max_param_count;

	if (!prs_init(&ps, 0, NULL, False)
	    || !notify_marshall_changes(fsp->notify, &ps)) {
		change_notify_reply_packet(request_buf, NT_STATUS_NO_MEMORY);
		goto done;
	}

	if (prs_offset(&ps) > max_param_count) {
		/*
		 * We exceed what the client is willing to accept. Send
		 * nothing.
		 */
		change_notify_reply_packet(request_buf, NT_STATUS_OK);
		goto done;
	}

	if (!(outbuf = SMB_MALLOC_ARRAY(char, buflen))) {
		change_notify_reply_packet(request_buf, NT_STATUS_NO_MEMORY);
		goto done;
	}

	construct_reply_common(request_buf, outbuf);

	if (send_nt_replies(outbuf, buflen, NT_STATUS_OK, prs_data_p(&ps),
			    prs_offset(&ps), NULL, 0) == -1) {
		exit_server("change_notify_reply_packet: send_smb failed.");
	}

 done:
	SAFE_FREE(outbuf);
	prs_mem_free(&ps);
	fsp->notify->num_changes = 0;
	TALLOC_FREE(fsp->notify->changes);
}

/****************************************************************************
 Remove an entry from the list and free it, also closing any
 directory handle if necessary.
*****************************************************************************/

static void change_notify_remove(struct change_notify *cnbp)
{
	cnotify->remove_notify(cnbp->change_data);
	DLIST_REMOVE(change_notify_list, cnbp);
	ZERO_STRUCTP(cnbp);
	SAFE_FREE(cnbp);
}

/****************************************************************************
 Delete entries by fnum from the change notify pending queue.
*****************************************************************************/

void remove_pending_change_notify_requests_by_fid(files_struct *fsp, NTSTATUS status)
{
	struct change_notify *cnbp, *next;

	for (cnbp=change_notify_list; cnbp; cnbp=next) {
		next=cnbp->next;
		if (cnbp->fsp->fnum == fsp->fnum) {
			change_notify_reply_packet(cnbp->request_buf, status);
			change_notify_remove(cnbp);
		}
	}
}

/****************************************************************************
 Delete entries by mid from the change notify pending queue. Always send reply.
*****************************************************************************/

void remove_pending_change_notify_requests_by_mid(int mid)
{
	struct change_notify *cnbp, *next;

	for (cnbp=change_notify_list; cnbp; cnbp=next) {
		next=cnbp->next;
		if(SVAL(cnbp->request_buf,smb_mid) == mid) {
			change_notify_reply_packet(cnbp->request_buf,
						   NT_STATUS_CANCELLED);
			change_notify_remove(cnbp);
		}
	}
}

/****************************************************************************
 Delete entries by filename and cnum from the change notify pending queue.
 Always send reply.
*****************************************************************************/

void remove_pending_change_notify_requests_by_filename(files_struct *fsp, NTSTATUS status)
{
	struct change_notify *cnbp, *next;

	for (cnbp=change_notify_list; cnbp; cnbp=next) {
		next=cnbp->next;
		/*
		 * We know it refers to the same directory if the connection number and
		 * the filename are identical.
		 */
		if((cnbp->fsp->conn == fsp->conn) && strequal(cnbp->fsp->fsp_name,fsp->fsp_name)) {
			change_notify_reply_packet(cnbp->request_buf, status);
			change_notify_remove(cnbp);
		}
	}
}

/****************************************************************************
 Set the current change notify timeout to the lowest value across all service
 values.
****************************************************************************/

void set_change_notify_timeout(int val)
{
	if (val > 0) {
		cnotify->select_time = MIN(cnotify->select_time, val);
	}
}

/****************************************************************************
 Longest time to sleep for before doing a change notify scan.
****************************************************************************/

int change_notify_timeout(void)
{
	return cnotify->select_time;
}

/****************************************************************************
 Process the change notify queue. Note that this is only called as root.
 Returns True if there are still outstanding change notify requests on the
 queue.
*****************************************************************************/

BOOL process_pending_change_notify_queue(time_t t)
{
	struct change_notify *cnbp, *next;
	uint16 vuid;

	for (cnbp=change_notify_list; cnbp; cnbp=next) {
		next=cnbp->next;

		vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID : SVAL(cnbp->request_buf,smb_uid);

		if (cnbp->fsp->notify->num_changes != 0) {
			DEBUG(10,("process_pending_change_notify_queue: %s "
				  "has %d changes!\n", cnbp->fsp->fsp_name,
				  cnbp->fsp->notify->num_changes));
			change_notify_reply(cnbp->request_buf,
					    cnbp->max_param_count,
					    cnbp->fsp);
			change_notify_remove(cnbp);
			continue;
		}

		if (cnotify->check_notify(cnbp->fsp->conn, vuid,
					  cnbp->fsp->fsp_name, cnbp->flags,
					  cnbp->change_data, t)) {
			DEBUG(10,("process_pending_change_notify_queue: dir "
				  "%s changed !\n", cnbp->fsp->fsp_name ));
			change_notify_reply(cnbp->request_buf,
					    cnbp->max_param_count,
					    cnbp->fsp);
			change_notify_remove(cnbp);
		}
	}

	return (change_notify_list != NULL);
}

/****************************************************************************
 Now queue an entry on the notify change list.
 We only need to save smb_size bytes from this incoming packet
 as we will always by returning a 'read the directory yourself'
 error.
****************************************************************************/

BOOL change_notify_set(char *inbuf, files_struct *fsp, connection_struct *conn,
		       uint32 flags, uint32 max_param_count)
{
	struct change_notify *cnbp;

	if((cnbp = SMB_MALLOC_P(struct change_notify)) == NULL) {
		DEBUG(0,("change_notify_set: malloc fail !\n" ));
		return False;
	}

	ZERO_STRUCTP(cnbp);

	memcpy(cnbp->request_buf, inbuf, smb_size);
	cnbp->fsp = fsp;
	cnbp->flags = flags;
	cnbp->max_param_count = max_param_count;
	cnbp->change_data = cnotify->register_notify(conn, fsp->fsp_name,
						     flags);
	
	if (!cnbp->change_data) {
		SAFE_FREE(cnbp);
		return False;
	}

	DLIST_ADD(change_notify_list, cnbp);

	/* Push the MID of this packet on the signing queue. */
	srv_defer_sign_response(SVAL(inbuf,smb_mid));

	return True;
}

int change_notify_fd(void)
{
	if (cnotify) {
		return cnotify->notification_fd;
	}

	return -1;
}

/* notify message definition

Offset  Data			length.
0	SMB_DEV_T dev		8
8	SMB_INO_T inode		8
16	uint32 action		4
20..	name
*/

#define MSG_NOTIFY_MESSAGE_SIZE 21 /* Includes at least the '\0' terminator */

struct notify_message {
	SMB_DEV_T dev;
	SMB_INO_T inode;
	uint32_t action;
	char *name;
};

static DATA_BLOB notify_message_to_buf(const struct notify_message *msg)
{
	DATA_BLOB result;
	size_t len;

	len = strlen(msg->name);

	result = data_blob(NULL, MSG_NOTIFY_MESSAGE_SIZE + len);
	if (!result.data) {
		return result;
	}

	SDEV_T_VAL(result.data, 0, msg->dev);
	SINO_T_VAL(result.data, 8, msg->inode);
	SIVAL(result.data, 16, msg->action);
	memcpy(result.data+20, msg->name, len+1);

	return result;
}

static BOOL buf_to_notify_message(void *buf, size_t len,
				  struct notify_message *msg)
{
	if (len < MSG_NOTIFY_MESSAGE_SIZE) {
		DEBUG(0, ("Got invalid notify message of len %d\n", len));
		return False;
	}

	msg->dev     = DEV_T_VAL(buf, 0);
	msg->inode   = INO_T_VAL(buf, 8);
	msg->action  = IVAL(buf, 16);
	msg->name    = ((char *)buf)+20;
	return True;
}

void notify_action(connection_struct *conn, const char *parent,
		   const char *name, uint32_t action)
{
	struct share_mode_lock *lck;
	SMB_STRUCT_STAT sbuf;
	int i;
	struct notify_message msg;
	DATA_BLOB blob;

	struct process_id *pids;
	int num_pids;

	DEBUG(10, ("notify_action: parent=%s, name=%s, action=%u\n",
		   parent, name, (unsigned)action));

	if (SMB_VFS_STAT(conn, parent, &sbuf) != 0) {
		/*
		 * Not 100% critical, ignore failure
		 */
		return;
	}

	if (!(lck = get_share_mode_lock(NULL, sbuf.st_dev, sbuf.st_ino,
					NULL, NULL))) {
		return;
	}

	msg.dev = sbuf.st_dev;
	msg.inode = sbuf.st_ino;
	msg.action = action;
	msg.name = CONST_DISCARD(char *, name);

	blob = notify_message_to_buf(&msg);
	if (blob.data == NULL) {
		DEBUG(0, ("notify_message_to_buf failed\n"));
		return;
	}

	pids = NULL;
	num_pids = 0;

	become_root_uid_only();

	for (i=0; i<lck->num_share_modes; i++) {
		struct share_mode_entry *e = &lck->share_modes[i];
		int j;
		struct process_id *tmp;

		for (j=0; j<num_pids; j++) {
			if (procid_equal(&e->pid, &pids[j])) {
				break;
			}
		}

		if (j < num_pids) {
			/*
			 * Already sent to that process, skip it
			 */
			continue;
		}

		message_send_pid(lck->share_modes[i].pid, MSG_SMB_NOTIFY,
				 blob.data, blob.length, True);

		if (!(tmp = TALLOC_REALLOC_ARRAY(lck, pids, struct process_id,
						 num_pids+1))) {
			DEBUG(0, ("realloc failed\n"));
			break;
		}
		pids = tmp;
		pids[num_pids] = e->pid;
		num_pids += 1;
	}

	unbecome_root_uid_only();

	data_blob_free(&blob);
	TALLOC_FREE(lck);
}

static void notify_message_callback(int msgtype, struct process_id pid,
				    void *buf, size_t len)
{
	struct notify_message msg;
	files_struct *fsp;
	struct notify_change *changes, *change;
	struct change_notify *cnbp;

	if (!buf_to_notify_message(buf, len, &msg)) {
		return;
	}

	DEBUG(10, ("Received notify_message for 0x%x/%.0f: %d\n",
		   (unsigned)msg.dev, (double)msg.inode, msg.action));

	fsp = NULL;

	for (cnbp = change_notify_list; cnbp != NULL; cnbp = cnbp->next) {
		if ((cnbp->fsp->dev == msg.dev)
		    && (cnbp->fsp->inode == msg.inode)) {
			break;
		}
	}

	if (cnbp != NULL) {
		DEBUG(10, ("Found pending change notify for %s\n",
			   cnbp->fsp->fsp_name));
		fsp = cnbp->fsp;
		SMB_ASSERT(fsp->notify->num_changes == 0);
	}

	if ((fsp == NULL)
	    && !(fsp = file_find_dir_lowest_id(msg.dev, msg.inode))) {
		DEBUG(10, ("notify_message: did not find fsp\n"));
		return;
	}

	if (!(changes = TALLOC_REALLOC_ARRAY(
		      fsp->notify, fsp->notify->changes,
		      struct notify_change, fsp->notify->num_changes+1))) {
		DEBUG(0, ("talloc_realloc failed\n"));
		return;
	}

	fsp->notify->changes = changes;

	change = &(fsp->notify->changes[fsp->notify->num_changes]);

	if (!(change->name = talloc_strdup(changes, msg.name))) {
		DEBUG(0, ("talloc_strdup failed\n"));
		return;
	}
	change->action = msg.action;
	fsp->notify->num_changes += 1;

	if (cnbp != NULL) {
		/*
		 * Respond directly, we have a someone waiting for this change
		 */
		DEBUG(10, ("Found pending cn for %s, responding directly\n",
			   cnbp->fsp->fsp_name));
		change_notify_reply(cnbp->request_buf, cnbp->max_param_count,
				    cnbp->fsp);
		change_notify_remove(cnbp);
		return;
	}
}

/****************************************************************************
 Initialise the change notify subsystem.
****************************************************************************/

BOOL init_change_notify(void)
{
	cnotify = NULL;

#if HAVE_KERNEL_CHANGE_NOTIFY
	if (cnotify == NULL && lp_kernel_change_notify())
		cnotify = kernel_notify_init();
#endif
#if HAVE_FAM_CHANGE_NOTIFY
	if (cnotify == NULL && lp_fam_change_notify())
		cnotify = fam_notify_init();
#endif
	if (!cnotify) cnotify = hash_notify_init();
	
	if (!cnotify) {
		DEBUG(0,("Failed to init change notify system\n"));
		return False;
	}

	message_register(MSG_SMB_NOTIFY, notify_message_callback);

	return True;
}