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 * @_id: one byte nhc id value.
20 * @_idmask: one byte nhc id mask value.
21 * @_uncompress: callback for uncompression call.
22 * @_compress: callback for compression call.
23 */
24#define LOWPAN_NHC(__nhc, _name, _nexthdr,	\
25		   _hdrlen, _id, _idmask,	\
26		   _uncompress, _compress)	\
27static const struct lowpan_nhc __nhc = {	\
28	.name		= _name,		\
29	.nexthdr	= _nexthdr,		\
30	.nexthdrlen	= _hdrlen,		\
31	.id		= _id,			\
32	.idmask		= _idmask,		\
33	.uncompress	= _uncompress,		\
34	.compress	= _compress,		\
35}
36
37#define module_lowpan_nhc(__nhc)		\
38static int __init __nhc##_init(void)		\
39{						\
40	return lowpan_nhc_add(&(__nhc));	\
41}						\
42module_init(__nhc##_init);			\
43static void __exit __nhc##_exit(void)		\
44{						\
45	lowpan_nhc_del(&(__nhc));		\
46}						\
47module_exit(__nhc##_exit);
48
49/**
50 * struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
51 *
52 * @name: name of the specific next header compression
53 * @nexthdr: next header value of the protocol which should be compressed.
54 * @nexthdrlen: ipv6 nexthdr len for the reserved space.
55 * @id: one byte nhc id value.
56 * @idmask: one byte nhc id mask value.
57 * @compress: callback to do the header compression.
58 * @uncompress: callback to do the header uncompression.
59 */
60struct lowpan_nhc {
61	const char	*name;
62	u8		nexthdr;
63	size_t		nexthdrlen;
64	u8		id;
65	u8		idmask;
66
67	int		(*uncompress)(struct sk_buff *skb, size_t needed);
68	int		(*compress)(struct sk_buff *skb, u8 **hc_ptr);
69};
70
71/**
72 * lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
73 *
74 * @nexthdr: ipv6 nexthdr value.
75 */
76struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);
77
78/**
79 * lowpan_nhc_check_compression - checks if we support compression format. If
80 *	we support the nhc by nexthdr field, the function will return 0. If we
81 *	don't support the nhc by nexthdr this function will return -ENOENT.
82 *
83 * @skb: skb of 6LoWPAN header to read nhc and replace header.
84 * @hdr: ipv6hdr to check the nexthdr value
85 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
86 *	    replaced header.
87 */
88int lowpan_nhc_check_compression(struct sk_buff *skb,
89				 const struct ipv6hdr *hdr, u8 **hc_ptr);
90
91/**
92 * lowpan_nhc_do_compression - calling compress callback for nhc
93 *
94 * @skb: skb of 6LoWPAN header to read nhc and replace header.
95 * @hdr: ipv6hdr to set the nexthdr value
96 * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
97 *	    replaced header.
98 */
99int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
100			      u8 **hc_ptr);
101
102/**
103 * lowpan_nhc_do_uncompression - calling uncompress callback for nhc
104 *
105 * @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
106 * @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
107 * @dev: netdevice for print logging information.
108 * @hdr: ipv6hdr for setting nexthdr value.
109 */
110int lowpan_nhc_do_uncompression(struct sk_buff *skb,
111				const struct net_device *dev,
112				struct ipv6hdr *hdr);
113
114/**
115 * lowpan_nhc_add - register a next header compression to framework
116 *
117 * @nhc: nhc which should be add.
118 */
119int lowpan_nhc_add(const struct lowpan_nhc *nhc);
120
121/**
122 * lowpan_nhc_del - delete a next header compression from framework
123 *
124 * @nhc: nhc which should be delete.
125 */
126void lowpan_nhc_del(const struct lowpan_nhc *nhc);
127
128/**
129 * lowpan_nhc_init - adding all default nhcs
130 */
131void lowpan_nhc_init(void);
132
133#endif /* __6LOWPAN_NHC_H */
134