add ECN support in layer-3.

 - implement the tunnel egress rule in ip_ecn_egress() in ip_ecn.c.
   make ip{,6}_ecn_egress() return integer to tell the caller that
   this packet should be dropped.
 - handle ECN at fragment reassembly in ip_input.c and frag6.c.

Obtained from:	KAME

1 files changed, 15 insertions, 4 deletions

diff --git a/sys/netinet/ip.h b/sys/netinet/ip.h
index 24f66ceb24db..025ad085d146 100644
--- a/sys/netinet/ip.h
+++ b/sys/netinet/ip.h
@@ -84,10 +84,11 @@ CTASSERT(sizeof (struct ip) == 20);
 #define	IPTOS_THROUGHPUT	0x08
 #define	IPTOS_RELIABILITY	0x04
 #define	IPTOS_MINCOST		0x02
-/* ECN bits proposed by Sally Floyd */
-#define	IPTOS_CE		0x01	/* congestion experienced */
-#define	IPTOS_ECT		0x02	/* ECN-capable transport */
-
+#if 1
+/* ECN RFC3168 obsoletes RFC2481, and these will be deprecated soon. */
+#define	IPTOS_CE		0x01
+#define	IPTOS_ECT		0x02
+#endif
 
 /*
  * Definitions for IP precedence (also in ip_tos) (hopefully unused)
@@ -102,6 +103,16 @@ CTASSERT(sizeof (struct ip) == 20);
 #define	IPTOS_PREC_ROUTINE		0x00
 
 /*
+ * ECN (Explicit Congestion Notification) codepoints in RFC3168
+ * mapped to the lower 2 bits of the TOS field.
+ */
+#define	IPTOS_ECN_NOTECT	0x00	/* not-ECT */
+#define	IPTOS_ECN_ECT1		0x01	/* ECN-capable transport (1) */
+#define	IPTOS_ECN_ECT0		0x02	/* ECN-capable transport (0) */
+#define	IPTOS_ECN_CE		0x03	/* congestion experienced */
+#define	IPTOS_ECN_MASK		0x03	/* ECN field mask */
+
+/*
  * Definitions for options.
  */
 #define	IPOPT_COPIED(o)		((o)&0x80)