linux/net/6lowpan/nhc.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __6LOWPAN_NHC_H
#define __6LOWPAN_NHC_H

#include <linux/skbuff.h>
#include <linux/rbtree.h>
#include <linux/module.h>

#include <net/6lowpan.h>
#include <net/ipv6.h>

/**
 * LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
 *
 * @__nhc: variable name of the lowpan_nhc struct.
 * @_name: const char * of common header compression name.
 * @_nexthdr: ipv6 nexthdr field for the header compression.
 * @_nexthdrlen: ipv6 nexthdr len for the reserved space.
 * @_id: one byte nhc id value.
 * @_idmask: one byte nhc id mask value.
 * @_uncompress: callback for uncompression call.
 * @_compress: callback for compression call.
 */
#define LOWPAN_NHC(__nhc, _name, _nexthdr,	\
		   _hdrlen, _id, _idmask,	\
		   _uncompress, _compress) …

#define module_lowpan_nhc(__nhc) …

/**
 * struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
 *
 * @name: name of the specific next header compression
 * @nexthdr: next header value of the protocol which should be compressed.
 * @nexthdrlen: ipv6 nexthdr len for the reserved space.
 * @id: one byte nhc id value.
 * @idmask: one byte nhc id mask value.
 * @compress: callback to do the header compression.
 * @uncompress: callback to do the header uncompression.
 */
struct lowpan_nhc { … };

/**
 * lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
 *
 * @nexthdr: ipv6 nexthdr value.
 */
struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);

/**
 * lowpan_nhc_check_compression - checks if we support compression format. If
 *	we support the nhc by nexthdr field, the function will return 0. If we
 *	don't support the nhc by nexthdr this function will return -ENOENT.
 *
 * @skb: skb of 6LoWPAN header to read nhc and replace header.
 * @hdr: ipv6hdr to check the nexthdr value
 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
 *	    replaced header.
 */
int lowpan_nhc_check_compression(struct sk_buff *skb,
				 const struct ipv6hdr *hdr, u8 **hc_ptr);

/**
 * lowpan_nhc_do_compression - calling compress callback for nhc
 *
 * @skb: skb of 6LoWPAN header to read nhc and replace header.
 * @hdr: ipv6hdr to set the nexthdr value
 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
 *	    replaced header.
 */
int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
			      u8 **hc_ptr);

/**
 * lowpan_nhc_do_uncompression - calling uncompress callback for nhc
 *
 * @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
 * @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
 * @dev: netdevice for print logging information.
 * @hdr: ipv6hdr for setting nexthdr value.
 */
int lowpan_nhc_do_uncompression(struct sk_buff *skb,
				const struct net_device *dev,
				struct ipv6hdr *hdr);

/**
 * lowpan_nhc_add - register a next header compression to framework
 *
 * @nhc: nhc which should be add.
 */
int lowpan_nhc_add(const struct lowpan_nhc *nhc);

/**
 * lowpan_nhc_del - delete a next header compression from framework
 *
 * @nhc: nhc which should be delete.
 */
void lowpan_nhc_del(const struct lowpan_nhc *nhc);

/**
 * lowpan_nhc_init - adding all default nhcs
 */
void lowpan_nhc_init(void);

#endif /* __6LOWPAN_NHC_H */