net: 6lowpan: use array for find nhc id

This patch will remove the complete overengineered and overthinking rb data
structure for looking up the nhc by nhcid. Instead we using the existing
nhc next header array and iterate over it. It works now for 1 byte values
only. However there are only 1 byte nhc id values currently
supported and IANA also does not specify large than 1 byte values yet.
If there are 2 byte values for nhc ids specified we can revisit this
data structure and add support for it.
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Reviewed-by: Stefan Schmidt <stefan@datenfreihafen.org>
Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Link: https://lore.kernel.org/r/20220428030534.3220410-3-aahringo@redhat.comSigned-off-by: Stefan Schmidt <stefan@datenfreihafen.org>

net/6lowpan/nhc.c

@@ -12,77 +12,26 @@
 
 #include "nhc.h"
 
-static struct rb_root rb_root = RB_ROOT;
 static struct lowpan_nhc *lowpan_nexthdr_nhcs[NEXTHDR_MAX + 1];
 static DEFINE_SPINLOCK(lowpan_nhc_lock);
 
-static int lowpan_nhc_insert(struct lowpan_nhc *nhc)
+static struct lowpan_nhc *lowpan_nhc_by_nhcid(struct sk_buff *skb)
 {
-	struct rb_node **new = &rb_root.rb_node, *parent = NULL;
-
-	/* Figure out where to put new node */
-	while (*new) {
-		struct lowpan_nhc *this = rb_entry(*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;
-	}
+	struct lowpan_nhc *nhc;
+	int i;
+	u8 id;
 
-	/* Add new node and rebalance tree. */
-	rb_link_node(&nhc->node, parent, new);
-	rb_insert_color(&nhc->node, &rb_root);
+	if (!pskb_may_pull(skb, 1))
+		return NULL;
 
-	return 0;
-}
+	id = *skb->data;
 
-static void lowpan_nhc_remove(struct lowpan_nhc *nhc)
-{
-	rb_erase(&nhc->node, &rb_root);
-}
+	for (i = 0; i < NEXTHDR_MAX + 1; i++) {
+		nhc = lowpan_nexthdr_nhcs[i];
+		if (!nhc)
+			continue;
 
-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 = rb_entry(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
+		if ((id & nhc->idmask) == nhc->id)
 			return nhc;
 	}
 
@@ -191,16 +140,7 @@ int lowpan_nhc_do_uncompression(struct sk_buff *skb,
 
 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);
+	int ret = 0;
 
 	spin_lock_bh(&lowpan_nhc_lock);
 
@@ -209,10 +149,6 @@ int lowpan_nhc_add(struct lowpan_nhc *nhc)
 		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);
@@ -224,7 +160,6 @@ 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);

net/6lowpan/nhc.h

@@ -16,24 +16,20 @@
  * @_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.
+ * @_id: one byte nhc id value.
+ * @_idmask: one byte nhc id mask value.
  * @_uncompress: callback for uncompression call.
  * @_compress: callback for compression call.
  */
 #define LOWPAN_NHC(__nhc, _name, _nexthdr,	\
-		   _hdrlen, _idsetup, _idlen,	\
+		   _hdrlen, _id, _idmask,	\
 		   _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,		\
+	.id		= _id,			\
+	.idmask		= _idmask,		\
 	.uncompress	= _uncompress,		\
 	.compress	= _compress,		\
 }
@@ -53,27 +49,21 @@ 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.
+ * @id: one byte nhc id value.
+ * @idmask: one byte nhc id mask value.
  * @compress: callback to do the header compression.
  * @uncompress: callback to do the header uncompression.
  */
 struct lowpan_nhc {
-	struct rb_node	node;
 	const char	*name;
 	u8		nexthdr;
 	size_t		nexthdrlen;
-	u8		*id;
-	u8		*idmask;
-	size_t		idlen;
+	u8		id;
+	u8		idmask;
 
-	void		(*idsetup)(struct lowpan_nhc *nhc);
 	int		(*uncompress)(struct sk_buff *skb, size_t needed);
 	int		(*compress)(struct sk_buff *skb, u8 **hc_ptr);
 };

net/6lowpan/nhc_dest.c

@@ -6,18 +6,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_DEST_IDLEN	1
 #define LOWPAN_NHC_DEST_ID_0	0xe6
 #define LOWPAN_NHC_DEST_MASK_0	0xfe
 
-static void dest_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_DEST_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_DEST_MASK_0;
-}
-
 LOWPAN_NHC(nhc_dest, "RFC6282 Destination Options", NEXTHDR_DEST, 0,
-	   dest_nhid_setup, LOWPAN_NHC_DEST_IDLEN, NULL, NULL);
+	   LOWPAN_NHC_DEST_ID_0, LOWPAN_NHC_DEST_MASK_0,  NULL, NULL);
 
 module_lowpan_nhc(nhc_dest);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Destination Options compression");

net/6lowpan/nhc_fragment.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_FRAGMENT_IDLEN	1
 #define LOWPAN_NHC_FRAGMENT_ID_0	0xe4
 #define LOWPAN_NHC_FRAGMENT_MASK_0	0xfe
 
-static void fragment_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_FRAGMENT_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_FRAGMENT_MASK_0;
-}
-
 LOWPAN_NHC(nhc_fragment, "RFC6282 Fragment", NEXTHDR_FRAGMENT, 0,
-	   fragment_nhid_setup, LOWPAN_NHC_FRAGMENT_IDLEN, NULL, NULL);
+	   LOWPAN_NHC_FRAGMENT_ID_0, LOWPAN_NHC_FRAGMENT_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(nhc_fragment);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Fragment compression");

net/6lowpan/nhc_ghc_ext_dest.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_EXT_DEST_IDLEN	1
 #define LOWPAN_GHC_EXT_DEST_ID_0	0xb6
 #define LOWPAN_GHC_EXT_DEST_MASK_0	0xfe
 
-static void dest_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_EXT_DEST_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_EXT_DEST_MASK_0;
-}
-
 LOWPAN_NHC(ghc_ext_dest, "RFC7400 Destination Extension Header", NEXTHDR_DEST,
-	   0, dest_ghid_setup, LOWPAN_GHC_EXT_DEST_IDLEN, NULL, NULL);
+	   0, LOWPAN_GHC_EXT_DEST_ID_0, LOWPAN_GHC_EXT_DEST_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_ext_dest);
 MODULE_DESCRIPTION("6LoWPAN generic header destination extension compression");

net/6lowpan/nhc_ghc_ext_frag.c

@@ -5,19 +5,12 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_EXT_FRAG_IDLEN	1
 #define LOWPAN_GHC_EXT_FRAG_ID_0	0xb4
 #define LOWPAN_GHC_EXT_FRAG_MASK_0	0xfe
 
-static void frag_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_EXT_FRAG_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_EXT_FRAG_MASK_0;
-}
-
 LOWPAN_NHC(ghc_ext_frag, "RFC7400 Fragmentation Extension Header",
-	   NEXTHDR_FRAGMENT, 0, frag_ghid_setup,
-	   LOWPAN_GHC_EXT_FRAG_IDLEN, NULL, NULL);
+	   NEXTHDR_FRAGMENT, 0, LOWPAN_GHC_EXT_FRAG_ID_0,
+	   LOWPAN_GHC_EXT_FRAG_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_ext_frag);
 MODULE_DESCRIPTION("6LoWPAN generic header fragmentation extension compression");

net/6lowpan/nhc_ghc_ext_hop.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_EXT_HOP_IDLEN	1
 #define LOWPAN_GHC_EXT_HOP_ID_0		0xb0
 #define LOWPAN_GHC_EXT_HOP_MASK_0	0xfe
 
-static void hop_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_EXT_HOP_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_EXT_HOP_MASK_0;
-}
-
 LOWPAN_NHC(ghc_ext_hop, "RFC7400 Hop-by-Hop Extension Header", NEXTHDR_HOP, 0,
-	   hop_ghid_setup, LOWPAN_GHC_EXT_HOP_IDLEN, NULL, NULL);
+	   LOWPAN_GHC_EXT_HOP_ID_0, LOWPAN_GHC_EXT_HOP_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_ext_hop);
 MODULE_DESCRIPTION("6LoWPAN generic header hop-by-hop extension compression");

net/6lowpan/nhc_ghc_ext_route.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_EXT_ROUTE_IDLEN	1
 #define LOWPAN_GHC_EXT_ROUTE_ID_0	0xb2
 #define LOWPAN_GHC_EXT_ROUTE_MASK_0	0xfe
 
-static void route_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_EXT_ROUTE_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_EXT_ROUTE_MASK_0;
-}
-
 LOWPAN_NHC(ghc_ext_route, "RFC7400 Routing Extension Header", NEXTHDR_ROUTING,
-	   0, route_ghid_setup, LOWPAN_GHC_EXT_ROUTE_IDLEN, NULL, NULL);
+	   0, LOWPAN_GHC_EXT_ROUTE_ID_0, LOWPAN_GHC_EXT_ROUTE_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_ext_route);
 MODULE_DESCRIPTION("6LoWPAN generic header routing extension compression");

net/6lowpan/nhc_ghc_icmpv6.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_ICMPV6_IDLEN		1
 #define LOWPAN_GHC_ICMPV6_ID_0		0xdf
 #define LOWPAN_GHC_ICMPV6_MASK_0	0xff
 
-static void icmpv6_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_ICMPV6_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_ICMPV6_MASK_0;
-}
-
 LOWPAN_NHC(ghc_icmpv6, "RFC7400 ICMPv6", NEXTHDR_ICMP, 0,
-	   icmpv6_ghid_setup, LOWPAN_GHC_ICMPV6_IDLEN, NULL, NULL);
+	   LOWPAN_GHC_ICMPV6_ID_0, LOWPAN_GHC_ICMPV6_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_icmpv6);
 MODULE_DESCRIPTION("6LoWPAN generic header ICMPv6 compression");

net/6lowpan/nhc_ghc_udp.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_GHC_UDP_IDLEN	1
 #define LOWPAN_GHC_UDP_ID_0	0xd0
 #define LOWPAN_GHC_UDP_MASK_0	0xf8
 
-static void udp_ghid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_GHC_UDP_ID_0;
-	nhc->idmask[0] = LOWPAN_GHC_UDP_MASK_0;
-}
-
 LOWPAN_NHC(ghc_udp, "RFC7400 UDP", NEXTHDR_UDP, 0,
-	   udp_ghid_setup, LOWPAN_GHC_UDP_IDLEN, NULL, NULL);
+	   LOWPAN_GHC_UDP_ID_0, LOWPAN_GHC_UDP_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(ghc_udp);
 MODULE_DESCRIPTION("6LoWPAN generic header UDP compression");

net/6lowpan/nhc_hop.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_HOP_IDLEN	1
 #define LOWPAN_NHC_HOP_ID_0	0xe0
 #define LOWPAN_NHC_HOP_MASK_0	0xfe
 
-static void hop_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_HOP_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_HOP_MASK_0;
-}
-
 LOWPAN_NHC(nhc_hop, "RFC6282 Hop-by-Hop Options", NEXTHDR_HOP, 0,
-	   hop_nhid_setup, LOWPAN_NHC_HOP_IDLEN, NULL, NULL);
+	   LOWPAN_NHC_HOP_ID_0, LOWPAN_NHC_HOP_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(nhc_hop);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Hop-by-Hop Options compression");

net/6lowpan/nhc_ipv6.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_IPV6_IDLEN	1
 #define LOWPAN_NHC_IPV6_ID_0	0xee
 #define LOWPAN_NHC_IPV6_MASK_0	0xfe
 
-static void ipv6_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_IPV6_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_IPV6_MASK_0;
-}
-
-LOWPAN_NHC(nhc_ipv6, "RFC6282 IPv6", NEXTHDR_IPV6, 0, ipv6_nhid_setup,
-	   LOWPAN_NHC_IPV6_IDLEN, NULL, NULL);
+LOWPAN_NHC(nhc_ipv6, "RFC6282 IPv6", NEXTHDR_IPV6, 0, LOWPAN_NHC_IPV6_ID_0,
+	   LOWPAN_NHC_IPV6_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(nhc_ipv6);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 IPv6 compression");

net/6lowpan/nhc_mobility.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_MOBILITY_IDLEN	1
 #define LOWPAN_NHC_MOBILITY_ID_0	0xe8
 #define LOWPAN_NHC_MOBILITY_MASK_0	0xfe
 
-static void mobility_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_MOBILITY_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_MOBILITY_MASK_0;
-}
-
 LOWPAN_NHC(nhc_mobility, "RFC6282 Mobility", NEXTHDR_MOBILITY, 0,
-	   mobility_nhid_setup, LOWPAN_NHC_MOBILITY_IDLEN, NULL, NULL);
+	   LOWPAN_NHC_MOBILITY_ID_0, LOWPAN_NHC_MOBILITY_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(nhc_mobility);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Mobility compression");

net/6lowpan/nhc_routing.c

@@ -5,18 +5,11 @@
 
 #include "nhc.h"
 
-#define LOWPAN_NHC_ROUTING_IDLEN	1
 #define LOWPAN_NHC_ROUTING_ID_0		0xe2
 #define LOWPAN_NHC_ROUTING_MASK_0	0xfe
 
-static void routing_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_ROUTING_ID_0;
-	nhc->idmask[0] = LOWPAN_NHC_ROUTING_MASK_0;
-}
-
 LOWPAN_NHC(nhc_routing, "RFC6282 Routing", NEXTHDR_ROUTING, 0,
-	   routing_nhid_setup, LOWPAN_NHC_ROUTING_IDLEN, NULL, NULL);
+	   LOWPAN_NHC_ROUTING_ID_0, LOWPAN_NHC_ROUTING_MASK_0, NULL, NULL);
 
 module_lowpan_nhc(nhc_routing);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 Routing compression");

net/6lowpan/nhc_udp.c

@@ -14,7 +14,6 @@
 
 #define LOWPAN_NHC_UDP_MASK		0xF8
 #define LOWPAN_NHC_UDP_ID		0xF0
-#define LOWPAN_NHC_UDP_IDLEN		1
 
 #define LOWPAN_NHC_UDP_4BIT_PORT	0xF0B0
 #define LOWPAN_NHC_UDP_4BIT_MASK	0xFFF0
@@ -169,14 +168,8 @@ static int udp_compress(struct sk_buff *skb, u8 **hc_ptr)
 	return 0;
 }
 
-static void udp_nhid_setup(struct lowpan_nhc *nhc)
-{
-	nhc->id[0] = LOWPAN_NHC_UDP_ID;
-	nhc->idmask[0] = LOWPAN_NHC_UDP_MASK;
-}
-
 LOWPAN_NHC(nhc_udp, "RFC6282 UDP", NEXTHDR_UDP, sizeof(struct udphdr),
-	   udp_nhid_setup, LOWPAN_NHC_UDP_IDLEN, udp_uncompress, udp_compress);
+	   LOWPAN_NHC_UDP_ID, LOWPAN_NHC_UDP_MASK, udp_uncompress, udp_compress);
 
 module_lowpan_nhc(nhc_udp);
 MODULE_DESCRIPTION("6LoWPAN next header RFC6282 UDP compression");