Add some #define's for mbuf annotations.

As the comment in the code says, eventually there will be a proper
data structure (e.g NetBSD's struct m_tag) to store chains of
annotations, and mbuf-handling procedures will handle these chains
in the correct way.

Right now, these chains do not exist, and we just use the constants
defined here to implement simple ad-hoc solutions to remove some global
variables used so far to pass around informations about packets
being processed.

Global variables are not only ugly and make the code unreadable, they
also prevent from using parallelism in network stack processing.

(the 3-days MFC only refers to this commit, i.e. the PACKET_TAG_*
constants; the full mechanism will be committed and MFC'ed on a
longer timescale).

MFC after: 3 days

1 files changed, 48 insertions, 0 deletions

diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 5cfb1ae..dec48ec 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -410,6 +410,54 @@ struct mauxtag {
 	void	*p;
 };
 
+/*
+ * Some packet tags to identify different mbuf annotations.
+ *
+ * Eventually, these annotations will end up in an appropriate chain
+ * (struct m_tag or similar, e.g. as in NetBSD) properly managed by
+ * the mbuf handling routines.
+ *
+ * As a temporary and low impact solution to replace the even uglier
+ * approach used so far in some parts of the network stack (which relies
+ * on global variables), these annotations are stored in MT_CONTROL
+ * mbufs (or lookalikes) prepended to the actual mbuf chain.
+ *
+ *	m_type	= MT_CONTROL
+ *	m_flags = m_tag_id
+ *	m_next	= next buffer in chain.
+ *
+ * BE VERY CAREFUL not to pass these blocks to the mbuf handling routines.
+ *
+ */
+
+#define	m_tag_id	m_hdr.mh_flags
+
+/* Packet tag types -- first ones are from NetBSD */
+
+#define	PACKET_TAG_NONE				0  /* Nadda */
+#define	PACKET_TAG_IPSEC_IN_DONE		1  /* IPsec applied, in */
+#define	PACKET_TAG_IPSEC_OUT_DONE		2  /* IPsec applied, out */
+#define	PACKET_TAG_IPSEC_IN_CRYPTO_DONE		3  /* NIC IPsec crypto done */
+#define	PACKET_TAG_IPSEC_OUT_CRYPTO_NEEDED	4  /* NIC IPsec crypto req'ed */
+#define	PACKET_TAG_IPSEC_IN_COULD_DO_CRYPTO	5  /* NIC notifies IPsec */
+#define	PACKET_TAG_IPSEC_PENDING_TDB		6  /* Reminder to do IPsec */
+#define	PACKET_TAG_BRIDGE			7  /* Bridge processing done */
+#define	PACKET_TAG_GIF				8  /* GIF processing done */
+#define	PACKET_TAG_GRE				9  /* GRE processing done */
+#define	PACKET_TAG_IN_PACKET_CHECKSUM		10 /* NIC checksumming done */
+#define	PACKET_TAG_ENCAP			11 /* Encap.  processing */
+#define	PACKET_TAG_IPSEC_SOCKET			12 /* IPSEC socket ref */
+#define	PACKET_TAG_IPSEC_HISTORY		13 /* IPSEC history */
+#define	PACKET_TAG_IPV6_INPUT			14 /* IPV6 input processing */
+
+/* Packet tags used in the FreeBSD network stack */
+#define	PACKET_TAG_DUMMYNET			15 /* dummynet info */
+#define	PACKET_TAG_IPFW				16 /* ipfw classification */
+#define	PACKET_TAG_DIVERT			17 /* divert info */
+#define	PACKET_TAG_IPFORWARD			18 /* ipforward info */
+
+#define	PACKET_TAG_MAX				19
+
 extern	int max_datalen;		/* MHLEN - max_hdr */
 extern	int max_hdr;			/* largest link + protocol header */
 extern	int max_linkhdr;		/* largest link-level header */