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
committed by
Marcel Holtmann
Marcel Holtmann
parent
129a76931a
commit
92aa7c65d2
241
net/6lowpan/nhc.c
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241
net/6lowpan/nhc.c
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@@ -0,0 +1,241 @@
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/*
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* 6LoWPAN next header compression
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*
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*
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* Authors:
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* Alexander Aring <aar@pengutronix.de>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/netdevice.h>
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#include <net/ipv6.h>
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#include "nhc.h"
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static struct rb_root rb_root = RB_ROOT;
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static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX];
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static DEFINE_SPINLOCK(lowpan_nhc_lock);
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static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
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{
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struct rb_node **new = &rb_root.rb_node, *parent = NULL;
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/* Figure out where to put new node */
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while (*new) {
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struct lowpan_nhc *this = container_of(*new, struct lowpan_nhc,
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node);
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int result, len_dif, len;
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len_dif = nhc->idlen - this->idlen;
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if (nhc->idlen < this->idlen)
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len = nhc->idlen;
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else
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len = this->idlen;
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result = memcmp(nhc->id, this->id, len);
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if (!result)
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result = len_dif;
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parent = *new;
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if (result < 0)
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new = &((*new)->rb_left);
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else if (result > 0)
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new = &((*new)->rb_right);
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else
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return -EEXIST;
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}
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/* Add new node and rebalance tree. */
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rb_link_node(&nhc->node, parent, new);
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rb_insert_color(&nhc->node, &rb_root);
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return 0;
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}
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static void lowpan_nhc_remove(struct lowpan_nhc *nhc)
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{
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rb_erase(&nhc->node, &rb_root);
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}
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static struct lowpan_nhc *lowpan_nhc_by_nhcid(const struct sk_buff *skb)
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{
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struct rb_node *node = rb_root.rb_node;
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const u8 *nhcid_skb_ptr = skb->data;
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while (node) {
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struct lowpan_nhc *nhc = container_of(node, struct lowpan_nhc,
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node);
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u8 nhcid_skb_ptr_masked[LOWPAN_NHC_MAX_ID_LEN];
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int result, i;
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if (nhcid_skb_ptr + nhc->idlen > skb->data + skb->len)
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return NULL;
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/* copy and mask afterwards the nhid value from skb */
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memcpy(nhcid_skb_ptr_masked, nhcid_skb_ptr, nhc->idlen);
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for (i = 0; i < nhc->idlen; i++)
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nhcid_skb_ptr_masked[i] &= nhc->idmask[i];
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result = memcmp(nhcid_skb_ptr_masked, nhc->id, nhc->idlen);
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if (result < 0)
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node = node->rb_left;
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else if (result > 0)
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node = node->rb_right;
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else
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return nhc;
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}
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return NULL;
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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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struct lowpan_nhc *nhc;
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spin_lock_bh(&lowpan_nhc_lock);
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nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
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if (nhc && nhc->compress)
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*iphc0 |= LOWPAN_IPHC_NH_C;
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else
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lowpan_push_hc_data(hc_ptr, &hdr->nexthdr,
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sizeof(hdr->nexthdr));
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spin_unlock_bh(&lowpan_nhc_lock);
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return 0;
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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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int ret;
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struct lowpan_nhc *nhc;
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spin_lock_bh(&lowpan_nhc_lock);
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nhc = lowpan_nexthdr_nhcs[hdr->nexthdr];
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/* check if the nhc module was removed in unlocked part.
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* TODO: this is a workaround we should prevent unloading
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* of nhc modules while unlocked part, this will always drop
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* the lowpan packet but it's very unlikely.
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*
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* Solution isn't easy because we need to decide at
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* lowpan_nhc_check_compression if we do a compression or not.
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* Because the inline data which is added to skb, we can't move this
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* handling.
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*/
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if (unlikely(!nhc || !nhc->compress)) {
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ret = -EINVAL;
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goto out;
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}
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/* In the case of RAW sockets the transport header is not set by
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* the ip6 stack so we must set it ourselves
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*/
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if (skb->transport_header == skb->network_header)
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skb_set_transport_header(skb, sizeof(struct ipv6hdr));
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ret = nhc->compress(skb, hc_ptr);
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if (ret < 0)
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goto out;
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/* skip the transport header */
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skb_pull(skb, nhc->nexthdrlen);
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out:
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spin_unlock_bh(&lowpan_nhc_lock);
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return ret;
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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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struct lowpan_nhc *nhc;
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int ret;
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spin_lock_bh(&lowpan_nhc_lock);
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nhc = lowpan_nhc_by_nhcid(skb);
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if (nhc) {
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if (nhc->uncompress) {
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ret = nhc->uncompress(skb, sizeof(struct ipv6hdr) +
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nhc->nexthdrlen);
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if (ret < 0) {
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spin_unlock_bh(&lowpan_nhc_lock);
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return ret;
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}
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} else {
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spin_unlock_bh(&lowpan_nhc_lock);
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netdev_warn(dev, "received nhc id for %s which is not implemented.\n",
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nhc->name);
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return -ENOTSUPP;
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}
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} else {
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spin_unlock_bh(&lowpan_nhc_lock);
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netdev_warn(dev, "received unknown nhc id which was not found.\n");
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return -ENOENT;
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}
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hdr->nexthdr = nhc->nexthdr;
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skb_reset_transport_header(skb);
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raw_dump_table(__func__, "raw transport header dump",
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skb_transport_header(skb), nhc->nexthdrlen);
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spin_unlock_bh(&lowpan_nhc_lock);
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return 0;
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}
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int lowpan_nhc_add(struct lowpan_nhc *nhc)
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{
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int ret;
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if (!nhc->idlen || !nhc->idsetup)
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return -EINVAL;
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WARN_ONCE(nhc->idlen > LOWPAN_NHC_MAX_ID_LEN,
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"LOWPAN_NHC_MAX_ID_LEN should be updated to %zd.\n",
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nhc->idlen);
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nhc->idsetup(nhc);
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spin_lock_bh(&lowpan_nhc_lock);
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if (lowpan_nexthdr_nhcs[nhc->nexthdr]) {
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ret = -EEXIST;
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goto out;
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}
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ret = lowpan_nhc_insert(nhc);
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if (ret < 0)
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goto out;
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lowpan_nexthdr_nhcs[nhc->nexthdr] = nhc;
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out:
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spin_unlock_bh(&lowpan_nhc_lock);
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return ret;
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}
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EXPORT_SYMBOL(lowpan_nhc_add);
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void lowpan_nhc_del(struct lowpan_nhc *nhc)
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{
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spin_lock_bh(&lowpan_nhc_lock);
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lowpan_nhc_remove(nhc);
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lowpan_nexthdr_nhcs[nhc->nexthdr] = NULL;
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spin_unlock_bh(&lowpan_nhc_lock);
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synchronize_net();
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}
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EXPORT_SYMBOL(lowpan_nhc_del);
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