1/* SPDX-License-Identifier: GPL-2.0 */
  2#ifndef __6LOWPAN_NHC_H
  3#define __6LOWPAN_NHC_H
  4
  5#include <linux/skbuff.h>
  6#include <linux/rbtree.h>
  7#include <linux/module.h>
  8
  9#include <net/6lowpan.h>
 10#include <net/ipv6.h>
 11
 12/**
 13 * LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
 14 *
 15 * @__nhc: variable name of the lowpan_nhc struct.
 16 * @_name: const char * of common header compression name.
 17 * @_nexthdr: ipv6 nexthdr field for the header compression.
 18 * @_nexthdrlen: ipv6 nexthdr len for the reserved space.
 19 * @_idsetup: callback to setup id and mask values.
 20 * @_idlen: len for the next header id and mask, should be always the same.
 21 * @_uncompress: callback for uncompression call.
 22 * @_compress: callback for compression call.
 23 */
 24#define LOWPAN_NHC(__nhc, _name, _nexthdr,	\
 25		   _hdrlen, _idsetup, _idlen,	\
 26		   _uncompress, _compress)	\
 27static u8 __nhc##_val[_idlen];			\
 28static u8 __nhc##_mask[_idlen];			\
 29static struct lowpan_nhc __nhc = {		\
 30	.name		= _name,		\
 31	.nexthdr	= _nexthdr,		\
 32	.nexthdrlen	= _hdrlen,		\
 33	.id		= __nhc##_val,		\
 34	.idmask		= __nhc##_mask,		\
 35	.idlen		= _idlen,		\
 36	.idsetup	= _idsetup,		\
 37	.uncompress	= _uncompress,		\
 38	.compress	= _compress,		\
 39}
 40
 41#define module_lowpan_nhc(__nhc)		\
 42static int __init __nhc##_init(void)		\
 43{						\
 44	return lowpan_nhc_add(&(__nhc));	\
 45}						\
 46module_init(__nhc##_init);			\
 47static void __exit __nhc##_exit(void)		\
 48{						\
 49	lowpan_nhc_del(&(__nhc));		\
 50}						\
 51module_exit(__nhc##_exit);
 52
 53/**
 54 * struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
 55 *
 56 * @node: holder for the rbtree.
 57 * @name: name of the specific next header compression
 58 * @nexthdr: next header value of the protocol which should be compressed.
 59 * @nexthdrlen: ipv6 nexthdr len for the reserved space.
 60 * @id: array for nhc id. Note this need to be in network byteorder.
 61 * @mask: array for nhc id mask. Note this need to be in network byteorder.
 62 * @len: the length of the next header id and mask.
 63 * @setup: callback to setup fill the next header id value and mask.
 64 * @compress: callback to do the header compression.
 65 * @uncompress: callback to do the header uncompression.
 66 */
 67struct lowpan_nhc {
 68	struct rb_node	node;
 69	const char	*name;
 70	const u8	nexthdr;
 71	const size_t	nexthdrlen;
 72	u8		*id;
 73	u8		*idmask;
 74	const size_t	idlen;
 75
 76	void		(*idsetup)(struct lowpan_nhc *nhc);
 77	int		(*uncompress)(struct sk_buff *skb, size_t needed);
 78	int		(*compress)(struct sk_buff *skb, u8 **hc_ptr);
 79};
 80
 81/**
 82 * lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
 83 *
 84 * @nexthdr: ipv6 nexthdr value.
 85 */
 86struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);
 87
 88/**
 89 * lowpan_nhc_check_compression - checks if we support compression format. If
 90 *	we support the nhc by nexthdr field, the function will return 0. If we
 91 *	don't support the nhc by nexthdr this function will return -ENOENT.
 92 *
 93 * @skb: skb of 6LoWPAN header to read nhc and replace header.
 94 * @hdr: ipv6hdr to check the nexthdr value
 95 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
 96 *	    replaced header.
 97 */
 98int lowpan_nhc_check_compression(struct sk_buff *skb,
 99				 const struct ipv6hdr *hdr, u8 **hc_ptr);
100
101/**
102 * lowpan_nhc_do_compression - calling compress callback for nhc
103 *
104 * @skb: skb of 6LoWPAN header to read nhc and replace header.
105 * @hdr: ipv6hdr to set the nexthdr value
106 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
107 *	    replaced header.
108 */
109int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
110			      u8 **hc_ptr);
111
112/**
113 * lowpan_nhc_do_uncompression - calling uncompress callback for nhc
114 *
115 * @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
116 * @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
117 * @dev: netdevice for print logging information.
118 * @hdr: ipv6hdr for setting nexthdr value.
119 */
120int lowpan_nhc_do_uncompression(struct sk_buff *skb,
121				const struct net_device *dev,
122				struct ipv6hdr *hdr);
123
124/**
125 * lowpan_nhc_add - register a next header compression to framework
126 *
127 * @nhc: nhc which should be add.
128 */
129int lowpan_nhc_add(struct lowpan_nhc *nhc);
130
131/**
132 * lowpan_nhc_del - delete a next header compression from framework
133 *
134 * @nhc: nhc which should be delete.
135 */
136void lowpan_nhc_del(struct lowpan_nhc *nhc);
137
138/**
139 * lowpan_nhc_init - adding all default nhcs
140 */
141void lowpan_nhc_init(void);
142
143#endif /* __6LOWPAN_NHC_H */