/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 *      connector.h
 * 
 * 2004-2005 Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
 * All rights reserved.
 */
#ifndef __CONNECTOR_H
#define __CONNECTOR_H


#include <linux/refcount.h>

#include <linux/list.h>
#include <linux/workqueue.h>

#include <net/sock.h>
#include <uapi/linux/connector.h>

#define CN_CBQ_NAMELEN          32

struct cn_queue_dev {
        atomic_t refcnt;
        unsigned char name[CN_CBQ_NAMELEN];

        struct list_head queue_list;
        spinlock_t queue_lock;

        struct sock *nls;
};

struct cn_callback_id {
        unsigned char name[CN_CBQ_NAMELEN];
        struct cb_id id;
};

struct cn_callback_entry {
        struct list_head callback_entry;
        refcount_t refcnt;
        struct cn_queue_dev *pdev;

        struct cn_callback_id id;
        void (*callback) (struct cn_msg *, struct netlink_skb_parms *);

        u32 seq, group;
};

struct cn_dev {
        struct cb_id id;

        u32 seq, groups;
        struct sock *nls;

        struct cn_queue_dev *cbdev;
};

/**
 * cn_add_callback() - Registers new callback with connector core.
 *
 * @id:         unique connector's user identifier.
 *              It must be registered in connector.h for legal
 *              in-kernel users.
 * @name:       connector's callback symbolic name.
 * @callback:   connector's callback.
 *              parameters are %cn_msg and the sender's credentials
 */
int cn_add_callback(const struct cb_id *id, const char *name,
                    void (*callback)(struct cn_msg *, struct netlink_skb_parms *));
/**
 * cn_del_callback() - Unregisters new callback with connector core.
 *
 * @id:         unique connector's user identifier.
 */
void cn_del_callback(const struct cb_id *id);


/**
 * cn_netlink_send_mult - Sends message to the specified groups.
 *
 * @msg:        message header(with attached data).
 * @len:        Number of @msg to be sent.
 * @portid:     destination port.
 *              If non-zero the message will be sent to the given port,
 *              which should be set to the original sender.
 * @group:      destination group.
 *              If @portid and @group is zero, then appropriate group will
 *              be searched through all registered connector users, and
 *              message will be delivered to the group which was created
 *              for user with the same ID as in @msg.
 *              If @group is not zero, then message will be delivered
 *              to the specified group.
 * @gfp_mask:   GFP mask.
 * @filter:     Filter function to be used at netlink layer.
 * @filter_data:Filter data to be supplied to the filter function
 *
 * It can be safely called from softirq context, but may silently
 * fail under strong memory pressure.
 *
 * If there are no listeners for given group %-ESRCH can be returned.
 */
int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid,
                         u32 group, gfp_t gfp_mask,
                         netlink_filter_fn filter,
                         void *filter_data);

/**
 * cn_netlink_send - Sends message to the specified groups.
 *
 * @msg:        message header(with attached data).
 * @portid:     destination port.
 *              If non-zero the message will be sent to the given port,
 *              which should be set to the original sender.
 * @group:      destination group.
 *              If @portid and @group is zero, then appropriate group will
 *              be searched through all registered connector users, and
 *              message will be delivered to the group which was created
 *              for user with the same ID as in @msg.
 *              If @group is not zero, then message will be delivered
 *              to the specified group.
 * @gfp_mask:   GFP mask.
 *
 * It can be safely called from softirq context, but may silently
 * fail under strong memory pressure.
 *
 * If there are no listeners for given group %-ESRCH can be returned.
 */
int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 group, gfp_t gfp_mask);

int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,
                          const struct cb_id *id,
                          void (*callback)(struct cn_msg *, struct netlink_skb_parms *));
void cn_queue_del_callback(struct cn_queue_dev *dev, const struct cb_id *id);
void cn_queue_release_callback(struct cn_callback_entry *);

struct cn_queue_dev *cn_queue_alloc_dev(const char *name, struct sock *);
void cn_queue_free_dev(struct cn_queue_dev *dev);

int cn_cb_equal(const struct cb_id *, const struct cb_id *);

#endif                          /* __CONNECTOR_H */