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)	\
27 static u8 __nhc##_val[_idlen];			\
28 static u8 __nhc##_mask[_idlen];			\
29 static 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)		\
42 static int __init __nhc##_init(void)		\
43 {						\
44 	return lowpan_nhc_add(&(__nhc));	\
45 }						\
46 module_init(__nhc##_init);			\
47 static void __exit __nhc##_exit(void)		\
48 {						\
49 	lowpan_nhc_del(&(__nhc));		\
50 }						\
51 module_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  */
67 struct 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  */
86 struct 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  */
98 int 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  */
109 int 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  */
120 int 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  */
129 int 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  */
136 void lowpan_nhc_del(struct lowpan_nhc *nhc);
137 
138 /**
139  * lowpan_nhc_init - adding all default nhcs
140  */
141 void lowpan_nhc_init(void);
142 
143 #endif /* __6LOWPAN_NHC_H */
144