6lowpan: add nhc module for GHC routing extension header detection

Acked-by: Jukka Rissanen <[e-mail]>
Signed-off-by: Stefan Schmidt <[e-mail]>
Signed-off-by: Alexander Aring <[e-mail]>
Signed-off-by: Marcel Holtmann <[e-mail]>

net/6lowpan/Kconfig

···
 	  6LoWPAN IPv6 fragmentation option generic header compression
 	  according to RFC7400.
 
+config 6LOWPAN_GHC_EXT_HDR_ROUTE
+	tristate "GHC Routing Options Header Support"
+	---help---
+	  6LoWPAN IPv6 routing option generic header compression according
+	  to RFC7400.
+
 endif

net/6lowpan/Makefile

···
 obj-$(CONFIG_6LOWPAN_GHC_ICMPV6) += nhc_ghc_icmpv6.o
 obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_DEST) += nhc_ghc_ext_dest.o
 obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_FRAG) += nhc_ghc_ext_frag.o
+obj-$(CONFIG_6LOWPAN_GHC_EXT_HDR_ROUTE) += nhc_ghc_ext_route.o

net/6lowpan/nhc_ghc_ext_route.c

···
+/*
+ *	6LoWPAN Extension Header compression according to RFC7400
+ *
+ *	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 "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);
+
+module_lowpan_nhc(ghc_ext_route);
+MODULE_DESCRIPTION("6LoWPAN generic header routing extension compression");
+MODULE_LICENSE("GPL");