net/6lowpan/nhc.h

   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)      \
  27 static 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)                \
  38 static int __init __nhc##_init(void)            \
  39 {                                               \
  40         return lowpan_nhc_add(&(__nhc));        \
  41 }                                               \
  42 module_init(__nhc##_init);                      \
  43 static void __exit __nhc##_exit(void)           \
  44 {                                               \
  45         lowpan_nhc_del(&(__nhc));               \
  46 }                                               \
  47 module_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  */
  60 struct 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  */
  76 struct 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  */
  88 int 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  */
  99 int 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  */
 110 int 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  */
 119 int 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  */
 126 void lowpan_nhc_del(const struct lowpan_nhc *nhc);
 127
 128 /**
 129  * lowpan_nhc_init - adding all default nhcs
 130  */
 131 void lowpan_nhc_init(void);
 132
 133 #endif /* __6LOWPAN_NHC_H */