[DCCP]: Make feature negotiation more readable

This patch replaces cryptic feature negotiation messages of type

Oct 31 15:42:20 kernel: dccp_feat_change: feat change type=32 feat=1
Oct 31 15:42:21 kernel: dccp_feat_change: feat change type=34 feat=1
Oct 31 15:42:21 kernel: dccp_feat_change: feat change type=32 feat=5

into ones of type:

Nov  2 13:54:45 kernel: dccp_feat_change: ChangeL(CCID (1), 3)
Nov  2 13:54:45 kernel: dccp_feat_change: ChangeR(CCID (1), 3)
Nov  2 13:54:45 kernel: dccp_feat_change: ChangeL(Ack Ratio (5), 2)

Also,
	* completed the feature number list wrt RFC 4340 sec. 6.4
	* annotating which ones have been implemented so far
	* implemented rudimentary sanity checking in feat.c (FIXMEs)
	* some minor fixes

Commiter note: uninlined dccp_feat_name and dccp_feat_typename, for
               consistency with dccp_{state,packet}_name, that, BTW,
               should be compiled only if CONFIG_IP_DCCP_DEBUG is
               selected, leaving this to another cset tho. Also
               shortened dccp_feat_negotiation_debug to dccp_feat_debug.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

1 files changed, 39 insertions, 2 deletions

diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 6048373..2c373ad 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -12,9 +12,46 @@
  */
 
 #include <linux/types.h>
+#include "dccp.h"
 
-struct sock;
-struct dccp_minisock;
+static inline int dccp_feat_is_valid_length(u8 type, u8 feature, u8 len)
+{
+	/* sec. 6.1: Confirm has at least length 3,
+	 * sec. 6.2: Change  has at least length 4 */
+	if (len < 3)
+		return 1;
+	if (len < 4  && (type == DCCPO_CHANGE_L || type == DCCPO_CHANGE_R))
+		return 1;
+	/* XXX: add per-feature length validation (sec. 6.6.8) */
+	return 0;
+}
+
+static inline int dccp_feat_is_reserved(const u8 feat)
+{
+	return (feat > DCCPF_DATA_CHECKSUM &&
+		feat < DCCPF_MIN_CCID_SPECIFIC) ||
+	        feat == DCCPF_RESERVED;
+}
+
+/* feature negotiation knows only these four option types (RFC 4340, sec. 6) */
+static inline int dccp_feat_is_valid_type(const u8 optnum)
+{
+	return optnum >= DCCPO_CHANGE_L && optnum <= DCCPO_CONFIRM_R;
+
+}
+
+#ifdef CONFIG_IP_DCCP_DEBUG
+extern const char *dccp_feat_typename(const u8 type);
+extern const char *dccp_feat_name(const u8 feat);
+
+static inline void dccp_feat_debug(const u8 type, const u8 feat, const u8 val)
+{
+	dccp_pr_debug("%s(%s (%d), %d)\n", dccp_feat_typename(type),
+					   dccp_feat_name(feat), feat, val);
+}
+#else
+#define dccp_feat_debug(type, feat, val)
+#endif /* CONFIG_IP_DCCP_DEBUG */
 
 extern int  dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
 			     u8 *val, u8 len, gfp_t gfp);