6lowpan: add generic nhc layer interface
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>
This commit is contained in:
Alexander Aring
Marcel Holtmann
parent
129a76931a
commit
92aa7c65d2
3 changed files with 388 additions and 1 deletions
|
|
@ -1,3 +1,3 @@
|
|||
obj-$(CONFIG_6LOWPAN) := 6lowpan.o
|
||||
|
||||
6lowpan-y := iphc.o
|
||||
6lowpan-y := iphc.o nhc.o
|
||||
|
|
|
|||
241
net/6lowpan/nhc.c
Normal file
241
net/6lowpan/nhc.c
Normal file
|
|
@ -0,0 +1,241 @@
|
|||
/*
|
||||
* 6LoWPAN next header compression
|
||||
*
|
||||
*
|
||||
* Authors:
|
||||
* Alexander Aring <aar@pengutronix.de>
|
||||
*
|
||||
* This program is free software; you can redistribute it and/or
|
||||
* modify it under the terms of the GNU General Public License
|
||||
* as published by the Free Software Foundation; either version
|
||||
* 2 of the License, or (at your option) any later version.
|
||||
*/
|
||||
|
||||
#include <linux/netdevice.h>
|
||||
|
||||
#include <net/ipv6.h>
|
||||
|
||||
#include "nhc.h"
|
||||
|
||||
static struct rb_root rb_root = RB_ROOT;
|
||||
static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
|
||||
static DEFINE_SPINLOCK(lowpan_nhc_lock);
|
||||
|
||||
static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
|
||||
{
|
||||
struct rb_node **new = &rb_root.rb_node, *parent = NULL;
|
||||
|
||||
/* Figure out where to put new node */
|
||||
while (*new) {
|
||||
struct lowpan_nhc *this = container_of(*new, struct lowpan_nhc,
|
||||
node);
|
||||
int result, len_dif, len;
|
||||
|
||||
len_dif = nhc->idlen - this->idlen;
|
||||
|
||||
if (nhc->idlen < this->idlen)
|
||||
len = nhc->idlen;
|
||||
else
|
||||
len = this->idlen;
|
||||
|
||||
result = memcmp(nhc->id, this->id, len);
|
||||
if (!result)
|
||||
result = len_dif;
|
||||
|
||||
parent = *new;
|
||||
if (result < 0)
|
||||
new = &((*new)->rb_left);
|
||||
else if (result > 0)
|
||||
new = &((*new)->rb_right);
|
||||
else
|
||||
return -EEXIST;
|
||||
}
|
||||
|
||||
/* Add new node and rebalance tree. */
|
||||
rb_link_node(&nhc->node, parent, new);
|
||||
rb_insert_color(&nhc->node, &rb_root);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
static void lowpan_nhc_remove(struct lowpan_nhc *nhc)
|
||||
{
|
||||
rb_erase(&nhc->node, &rb_root);
|
||||
}
|
||||
|
||||
static struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb)
|
||||
{
|
||||
struct rb_node *node = rb_root.rb_node;
|
||||
const u8 *nhcid_skb_ptr = skb->data;
|
||||
|
||||
while (node) {
|
||||
struct lowpan_nhc *nhc = container_of(node, struct lowpan_nhc,
|
||||
node);
|
||||
u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN];
|
||||
int result, i;
|
||||
|
||||
if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len)
|
||||
return NULL;
|
||||
|
||||
/* copy and mask afterwards the nhid value from skb */
|
||||
memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen);
|
||||
for (i = 0; i < nhc->idlen; i++)
|
||||
nhcid_skb_ptr_masked[i] &= nhc->idmask[i];
|
||||
|
||||
result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen);
|
||||
if (result < 0)
|
||||
node = node->rb_left;
|
||||
else if (result > 0)
|
||||
node = node->rb_right;
|
||||
else
|
||||
return nhc;
|
||||
}
|
||||
|
||||
return NULL;
|
||||
}
|
||||
|
||||
int lowpan_nhc_check_compression(struct sk_buff *skb,
|
||||
const struct ipv6hdr *hdr, u8 **hc_ptr,
|
||||
u8 *iphc0)
|
||||
{
|
||||
struct lowpan_nhc *nhc;
|
||||
|
||||
spin_lock_bh(&lowpan_nhc_lock);
|
||||
|
||||
nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
|
||||
if (nhc && nhc->compress)
|
||||
*iphc0 |= LOWPAN_IPHC_NH_C;
|
||||
else
|
||||
lowpan_push_hc_data(hc_ptr, &hdr->nexthdr,
|
||||
sizeof(hdr->nexthdr));
|
||||
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
|
||||
u8 **hc_ptr)
|
||||
{
|
||||
int ret;
|
||||
struct lowpan_nhc *nhc;
|
||||
|
||||
spin_lock_bh(&lowpan_nhc_lock);
|
||||
|
||||
nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
|
||||
/* check if the nhc module was removed in unlocked part.
|
||||
* TODO: this is a workaround we should prevent unloading
|
||||
* of nhc modules while unlocked part, this will always drop
|
||||
* the lowpan packet but it's very unlikely.
|
||||
*
|
||||
* Solution isn't easy because we need to decide at
|
||||
* lowpan_nhc_check_compression if we do a compression or not.
|
||||
* Because the inline data which is added to skb, we can't move this
|
||||
* handling.
|
||||
*/
|
||||
if (unlikely(!nhc || !nhc->compress)) {
|
||||
ret = -EINVAL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
/* In the case of RAW sockets the transport header is not set by
|
||||
* the ip6 stack so we must set it ourselves
|
||||
*/
|
||||
if (skb->transport_header == skb->network_header)
|
||||
skb_set_transport_header(skb, sizeof(struct ipv6hdr));
|
||||
|
||||
ret = nhc->compress(skb, hc_ptr);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
||||
/* skip the transport header */
|
||||
skb_pull(skb, nhc->nexthdrlen);
|
||||
|
||||
out:
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
|
||||
return ret;
|
||||
}
|
||||
|
||||
int lowpan_nhc_do_uncompression(struct sk_buff *skb, struct net_device *dev,
|
||||
struct ipv6hdr *hdr)
|
||||
{
|
||||
struct lowpan_nhc *nhc;
|
||||
int ret;
|
||||
|
||||
spin_lock_bh(&lowpan_nhc_lock);
|
||||
|
||||
nhc = lowpan_nhc_by_nhcid(skb);
|
||||
if (nhc) {
|
||||
if (nhc->uncompress) {
|
||||
ret = nhc->uncompress(skb, sizeof(struct ipv6hdr) +
|
||||
nhc->nexthdrlen);
|
||||
if (ret < 0) {
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
return ret;
|
||||
}
|
||||
} else {
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
netdev_warn(dev, "received nhc id for %s which is not implemented.\n",
|
||||
nhc->name);
|
||||
return -ENOTSUPP;
|
||||
}
|
||||
} else {
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
netdev_warn(dev, "received unknown nhc id which was not found.\n");
|
||||
return -ENOENT;
|
||||
}
|
||||
|
||||
hdr->nexthdr = nhc->nexthdr;
|
||||
skb_reset_transport_header(skb);
|
||||
raw_dump_table(__func__, "raw transport header dump",
|
||||
skb_transport_header(skb), nhc->nexthdrlen);
|
||||
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
||||
int lowpan_nhc_add(struct lowpan_nhc *nhc)
|
||||
{
|
||||
int ret;
|
||||
|
||||
if (!nhc->idlen || !nhc->idsetup)
|
||||
return -EINVAL;
|
||||
|
||||
WARN_ONCE(nhc->idlen > LOWPAN_NHC_MAX_ID_LEN,
|
||||
"LOWPAN_NHC_MAX_ID_LEN should be updated to %zd.\n",
|
||||
nhc->idlen);
|
||||
|
||||
nhc->idsetup(nhc);
|
||||
|
||||
spin_lock_bh(&lowpan_nhc_lock);
|
||||
|
||||
if (lowpan_nexthdr_nhcs[nhc->nexthdr]) {
|
||||
ret = -EEXIST;
|
||||
goto out;
|
||||
}
|
||||
|
||||
ret = lowpan_nhc_insert(nhc);
|
||||
if (ret < 0)
|
||||
goto out;
|
||||
|
||||
lowpan_nexthdr_nhcs[nhc->nexthdr] = nhc;
|
||||
out:
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
return ret;
|
||||
}
|
||||
EXPORT_SYMBOL(lowpan_nhc_add);
|
||||
|
||||
void lowpan_nhc_del(struct lowpan_nhc *nhc)
|
||||
{
|
||||
spin_lock_bh(&lowpan_nhc_lock);
|
||||
|
||||
lowpan_nhc_remove(nhc);
|
||||
lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL;
|
||||
|
||||
spin_unlock_bh(&lowpan_nhc_lock);
|
||||
|
||||
synchronize_net();
|
||||
}
|
||||
EXPORT_SYMBOL(lowpan_nhc_del);
|
||||
146
net/6lowpan/nhc.h
Normal file
146
net/6lowpan/nhc.h
Normal file
|
|
@ -0,0 +1,146 @@
|
|||
#ifndef __6LOWPAN_NHC_H
|
||||
#define __6LOWPAN_NHC_H
|
||||
|
||||
#include <linux/skbuff.h>
|
||||
#include <linux/rbtree.h>
|
||||
#include <linux/module.h>
|
||||
|
||||
#include <net/6lowpan.h>
|
||||
#include <net/ipv6.h>
|
||||
|
||||
#define LOWPAN_NHC_MAX_ID_LEN 1
|
||||
|
||||
/**
|
||||
* LOWPAN_NHC - helper macro to generate nh id fields and lowpan_nhc struct
|
||||
*
|
||||
* @__nhc: variable name of the lowpan_nhc struct.
|
||||
* @_name: const char * of common header compression name.
|
||||
* @_nexthdr: ipv6 nexthdr field for the header compression.
|
||||
* @_nexthdrlen: ipv6 nexthdr len for the reserved space.
|
||||
* @_idsetup: callback to setup id and mask values.
|
||||
* @_idlen: len for the next header id and mask, should be always the same.
|
||||
* @_uncompress: callback for uncompression call.
|
||||
* @_compress: callback for compression call.
|
||||
*/
|
||||
#define LOWPAN_NHC(__nhc, _name, _nexthdr, \
|
||||
_hdrlen, _idsetup, _idlen, \
|
||||
_uncompress, _compress) \
|
||||
static u8 __nhc##_val[_idlen]; \
|
||||
static u8 __nhc##_mask[_idlen]; \
|
||||
static struct lowpan_nhc __nhc = { \
|
||||
.name = _name, \
|
||||
.nexthdr = _nexthdr, \
|
||||
.nexthdrlen = _hdrlen, \
|
||||
.id = __nhc##_val, \
|
||||
.idmask = __nhc##_mask, \
|
||||
.idlen = _idlen, \
|
||||
.idsetup = _idsetup, \
|
||||
.uncompress = _uncompress, \
|
||||
.compress = _compress, \
|
||||
}
|
||||
|
||||
#define module_lowpan_nhc(__nhc) \
|
||||
static int __init __nhc##_init(void) \
|
||||
{ \
|
||||
return lowpan_nhc_add(&(__nhc)); \
|
||||
} \
|
||||
module_init(__nhc##_init); \
|
||||
static void __exit __nhc##_exit(void) \
|
||||
{ \
|
||||
lowpan_nhc_del(&(__nhc)); \
|
||||
} \
|
||||
module_exit(__nhc##_exit);
|
||||
|
||||
/**
|
||||
* struct lowpan_nhc - hold 6lowpan next hdr compression ifnformation
|
||||
*
|
||||
* @node: holder for the rbtree.
|
||||
* @name: name of the specific next header compression
|
||||
* @nexthdr: next header value of the protocol which should be compressed.
|
||||
* @nexthdrlen: ipv6 nexthdr len for the reserved space.
|
||||
* @id: array for nhc id. Note this need to be in network byteorder.
|
||||
* @mask: array for nhc id mask. Note this need to be in network byteorder.
|
||||
* @len: the length of the next header id and mask.
|
||||
* @setup: callback to setup fill the next header id value and mask.
|
||||
* @compress: callback to do the header compression.
|
||||
* @uncompress: callback to do the header uncompression.
|
||||
*/
|
||||
struct lowpan_nhc {
|
||||
struct rb_node node;
|
||||
const char *name;
|
||||
const u8 nexthdr;
|
||||
const size_t nexthdrlen;
|
||||
u8 *id;
|
||||
u8 *idmask;
|
||||
const size_t idlen;
|
||||
|
||||
void (*idsetup)(struct lowpan_nhc *nhc);
|
||||
int (*uncompress)(struct sk_buff *skb, size_t needed);
|
||||
int (*compress)(struct sk_buff *skb, u8 **hc_ptr);
|
||||
};
|
||||
|
||||
/**
|
||||
* lowpan_nhc_by_nexthdr - return the 6lowpan nhc by ipv6 nexthdr.
|
||||
*
|
||||
* @nexthdr: ipv6 nexthdr value.
|
||||
*/
|
||||
struct lowpan_nhc *lowpan_nhc_by_nexthdr(u8 nexthdr);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_check_compression - checks if we support compression format. If
|
||||
* we support the nhc by nexthdr field, the 6LoWPAN iphc NHC bit will be
|
||||
* set. If we don't support nexthdr will be added as inline data to the
|
||||
* 6LoWPAN header.
|
||||
*
|
||||
* @skb: skb of 6LoWPAN header to read nhc and replace header.
|
||||
* @hdr: ipv6hdr to check the nexthdr value
|
||||
* @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
|
||||
* replaced header.
|
||||
* @iphc0: iphc0 pointer to set the 6LoWPAN NHC bit
|
||||
*/
|
||||
int lowpan_nhc_check_compression(struct sk_buff *skb,
|
||||
const struct ipv6hdr *hdr, u8 **hc_ptr,
|
||||
u8 *iphc0);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_do_compression - calling compress callback for nhc
|
||||
*
|
||||
* @skb: skb of 6LoWPAN header to read nhc and replace header.
|
||||
* @hdr: ipv6hdr to set the nexthdr value
|
||||
* @hc_ptr: pointer for 6LoWPAN header which should increment at the end of
|
||||
* replaced header.
|
||||
*/
|
||||
int lowpan_nhc_do_compression(struct sk_buff *skb, const struct ipv6hdr *hdr,
|
||||
u8 **hc_ptr);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_do_uncompression - calling uncompress callback for nhc
|
||||
*
|
||||
* @nhc: 6LoWPAN nhc context, get by lowpan_nhc_by_ functions.
|
||||
* @skb: skb of 6LoWPAN header, skb->data should be pointed to nhc id value.
|
||||
* @dev: netdevice for print logging information.
|
||||
* @hdr: ipv6hdr for setting nexthdr value.
|
||||
*/
|
||||
int lowpan_nhc_do_uncompression(struct sk_buff *skb, struct net_device *dev,
|
||||
struct ipv6hdr *hdr);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_add - register a next header compression to framework
|
||||
*
|
||||
* @nhc: nhc which should be add.
|
||||
*/
|
||||
int lowpan_nhc_add(struct lowpan_nhc *nhc);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_del - delete a next header compression from framework
|
||||
*
|
||||
* @nhc: nhc which should be delete.
|
||||
*/
|
||||
void lowpan_nhc_del(struct lowpan_nhc *nhc);
|
||||
|
||||
/**
|
||||
* lowpan_nhc_init - adding all default nhcs
|
||||
*/
|
||||
void lowpan_nhc_init(void);
|
||||
|
||||
#endif /* __6LOWPAN_NHC_H */
|
||||
Loading…
Reference in a new issue