net/6lowpan/nhc.h

0001 /* SPDX-License-Identifier: GPL-2.0 */
0002 #ifndef __6LOWPAN_NHC_H
0003 #define __6LOWPAN_NHC_H
0004
0005 #include <linux/skbuff.h>
0006 #include <linux/rbtree.h>
0007 #include <linux/module.h>
0008
0009 #include <net/6lowpan.h>
0010 #include <net/ipv6.h>
0011
0012 /**
0013  * LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
0014  *
0015  * @__nhc: variable name of the lowpan_nhc struct.
0016  * @_name: const char * of common header compression name.
0017  * @_nexthdr: ipv6 nexthdr field for the header compression.
0018  * @_nexthdrlen: ipv6 nexthdr len for the reserved space.
0019  * @_id: one byte nhc id value.
0020  * @_idmask: one byte nhc id mask value.
0021  * @_uncompress: callback for uncompression call.
0022  * @_compress: callback for compression call.
0023  */
0024 #define LOWPAN_NHC(__nhc, _name, _nexthdr,  \
0025            _hdrlen, _id, _idmask,   \
0026            _uncompress, _compress)  \
0027 static const struct lowpan_nhc __nhc = {    \
0028     .name       = _name,        \
0029     .nexthdr    = _nexthdr,     \
0030     .nexthdrlen = _hdrlen,      \
0031     .id     = _id,          \
0032     .idmask     = _idmask,      \
0033     .uncompress = _uncompress,      \
0034     .compress   = _compress,        \
0035 }
0036
0037 #define module_lowpan_nhc(__nhc)        \
0038 static int __init __nhc##_init(void)        \
0039 {                       \
0040     return lowpan_nhc_add(&(__nhc));    \
0041 }                       \
0042 module_init(__nhc##_init);          \
0043 static void __exit __nhc##_exit(void)       \
0044 {                       \
0045     lowpan_nhc_del(&(__nhc));       \
0046 }                       \
0047 module_exit(__nhc##_exit);
0048
0049 /**
0050  * struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
0051  *
0052  * @name: name of the specific next header compression
0053  * @nexthdr: next header value of the protocol which should be compressed.
0054  * @nexthdrlen: ipv6 nexthdr len for the reserved space.
0055  * @id: one byte nhc id value.
0056  * @idmask: one byte nhc id mask value.
0057  * @compress: callback to do the header compression.
0058  * @uncompress: callback to do the header uncompression.
0059  */
0060 struct lowpan_nhc {
0061     const char  *name;
0062     u8      nexthdr;
0063     size_t      nexthdrlen;
0064     u8      id;
0065     u8      idmask;
0066
0067     int     (*uncompress)(struct sk_buff *skb, size_t needed);
0068     int     (*compress)(struct sk_buff *skb, u8 **hc_ptr);
0069 };
0070
0071 /**
0072  * lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
0073  *
0074  * @nexthdr: ipv6 nexthdr value.
0075  */
0076 struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);
0077
0078 /**
0079  * lowpan_nhc_check_compression - checks if we support compression format. If
0080  *  we support the nhc by nexthdr field, the function will return 0. If we
0081  *  don't support the nhc by nexthdr this function will return -ENOENT.
0082  *
0083  * @skb: skb of 6LoWPAN header to read nhc and replace header.
0084  * @hdr: ipv6hdr to check the nexthdr value
0085  * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
0086  *      replaced header.
0087  */
0088 int lowpan_nhc_check_compression(struct sk_buff *skb,
0089                  const struct ipv6hdr *hdr, u8 **hc_ptr);
0090
0091 /**
0092  * lowpan_nhc_do_compression - calling compress callback for nhc
0093  *
0094  * @skb: skb of 6LoWPAN header to read nhc and replace header.
0095  * @hdr: ipv6hdr to set the nexthdr value
0096  * @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
0097  *      replaced header.
0098  */
0099 int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
0100                   u8 **hc_ptr);
0101
0102 /**
0103  * lowpan_nhc_do_uncompression - calling uncompress callback for nhc
0104  *
0105  * @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
0106  * @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
0107  * @dev: netdevice for print logging information.
0108  * @hdr: ipv6hdr for setting nexthdr value.
0109  */
0110 int lowpan_nhc_do_uncompression(struct sk_buff *skb,
0111                 const struct net_device *dev,
0112                 struct ipv6hdr *hdr);
0113
0114 /**
0115  * lowpan_nhc_add - register a next header compression to framework
0116  *
0117  * @nhc: nhc which should be add.
0118  */
0119 int lowpan_nhc_add(const struct lowpan_nhc *nhc);
0120
0121 /**
0122  * lowpan_nhc_del - delete a next header compression from framework
0123  *
0124  * @nhc: nhc which should be delete.
0125  */
0126 void lowpan_nhc_del(const struct lowpan_nhc *nhc);
0127
0128 /**
0129  * lowpan_nhc_init - adding all default nhcs
0130  */
0131 void lowpan_nhc_init(void);
0132
0133 #endif /* __6LOWPAN_NHC_H */