92aa7c65d2
This patch adds a generic next header compression layer interface. There exists various methods to do a header compression after 6LoWPAN header to save payload. This introduce a generic nhc header which allow a simple adding of a new header compression format instead of a static implementation inside the 6LoWPAN header compression and uncompression function. Signed-off-by: Alexander Aring <alex.aring@gmail.com> Cc: Martin Townsend <mtownsend1973@gmail.com> Reviewed-by: Stefan Schmidt <s.schmidt@samsung.com> Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
147 lines
4.4 KiB
C
147 lines
4.4 KiB
C
#ifndef __6LOWPAN_NHC_H
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#define __6LOWPAN_NHC_H
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#include <linux/skbuff.h>
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#include <linux/rbtree.h>
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#include <linux/module.h>
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#include <net/6lowpan.h>
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#include <net/ipv6.h>
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#define LOWPAN_NHC_MAX_ID_LEN 1
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/**
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* LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
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*
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* @__nhc: variable name of the lowpan_nhc struct.
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* @_name: const char * of common header compression name.
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* @_nexthdr: ipv6 nexthdr field for the header compression.
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* @_nexthdrlen: ipv6 nexthdr len for the reserved space.
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* @_idsetup: callback to setup id and mask values.
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* @_idlen: len for the next header id and mask, should be always the same.
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* @_uncompress: callback for uncompression call.
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* @_compress: callback for compression call.
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*/
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#define LOWPAN_NHC(__nhc, _name, _nexthdr, \
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_hdrlen, _idsetup, _idlen, \
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_uncompress, _compress) \
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static u8 __nhc##_val[_idlen]; \
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static u8 __nhc##_mask[_idlen]; \
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static struct lowpan_nhc __nhc = { \
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.name = _name, \
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.nexthdr = _nexthdr, \
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.nexthdrlen = _hdrlen, \
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.id = __nhc##_val, \
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.idmask = __nhc##_mask, \
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.idlen = _idlen, \
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.idsetup = _idsetup, \
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.uncompress = _uncompress, \
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.compress = _compress, \
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}
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#define module_lowpan_nhc(__nhc) \
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static int __init __nhc##_init(void) \
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{ \
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return lowpan_nhc_add(&(__nhc)); \
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} \
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module_init(__nhc##_init); \
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static void __exit __nhc##_exit(void) \
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{ \
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lowpan_nhc_del(&(__nhc)); \
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} \
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module_exit(__nhc##_exit);
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/**
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* struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
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*
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* @node: holder for the rbtree.
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* @name: name of the specific next header compression
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* @nexthdr: next header value of the protocol which should be compressed.
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* @nexthdrlen: ipv6 nexthdr len for the reserved space.
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* @id: array for nhc id. Note this need to be in network byteorder.
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* @mask: array for nhc id mask. Note this need to be in network byteorder.
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* @len: the length of the next header id and mask.
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* @setup: callback to setup fill the next header id value and mask.
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* @compress: callback to do the header compression.
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* @uncompress: callback to do the header uncompression.
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*/
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struct lowpan_nhc {
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struct rb_node node;
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const char *name;
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const u8 nexthdr;
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const size_t nexthdrlen;
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u8 *id;
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u8 *idmask;
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const size_t idlen;
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void (*idsetup)(struct lowpan_nhc *nhc);
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int (*uncompress)(struct sk_buff *skb, size_t needed);
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int (*compress)(struct sk_buff *skb, u8 **hc_ptr);
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};
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/**
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* lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
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*
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* @nexthdr: ipv6 nexthdr value.
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*/
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struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);
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/**
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* lowpan_nhc_check_compression - checks if we support compression format. If
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* we support the nhc by nexthdr field, the 6LoWPAN iphc NHC bit will be
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* set. If we don't support nexthdr will be added as inline data to the
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* 6LoWPAN header.
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*
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* @skb: skb of 6LoWPAN header to read nhc and replace header.
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* @hdr: ipv6hdr to check the nexthdr value
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* @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
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* replaced header.
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* @iphc0: iphc0 pointer to set the 6LoWPAN NHC bit
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*/
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int lowpan_nhc_check_compression(struct sk_buff *skb,
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const struct ipv6hdr *hdr, u8 **hc_ptr,
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u8 *iphc0);
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/**
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* lowpan_nhc_do_compression - calling compress callback for nhc
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*
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* @skb: skb of 6LoWPAN header to read nhc and replace header.
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* @hdr: ipv6hdr to set the nexthdr value
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* @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
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* replaced header.
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*/
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int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
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u8 **hc_ptr);
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/**
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* lowpan_nhc_do_uncompression - calling uncompress callback for nhc
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*
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* @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
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* @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
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* @dev: netdevice for print logging information.
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* @hdr: ipv6hdr for setting nexthdr value.
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*/
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int lowpan_nhc_do_uncompression(struct sk_buff *skb, struct net_device *dev,
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struct ipv6hdr *hdr);
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/**
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* lowpan_nhc_add - register a next header compression to framework
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*
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* @nhc: nhc which should be add.
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*/
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int lowpan_nhc_add(struct lowpan_nhc *nhc);
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/**
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* lowpan_nhc_del - delete a next header compression from framework
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*
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* @nhc: nhc which should be delete.
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*/
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void lowpan_nhc_del(struct lowpan_nhc *nhc);
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/**
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* lowpan_nhc_init - adding all default nhcs
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*/
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void lowpan_nhc_init(void);
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#endif /* __6LOWPAN_NHC_H */
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