segtree: only use prefix expressions for ranges for selected datatypes

It is uncommon to represent f.i. port number ranges as prefix expressions.

Introduce a datatype DTYPE_F_PREFIX flag to indicate that the preferred
representation of a range is a prefix and use it for segtree decomposition
to decide whether to use a range or prefix expression.

The ipaddr, ip6addr, mark and realm datatypes are changed to include the
DTYPE_F_PREFIX flag.

This fixes completely unreadable output in cases where the ranges are
representable as prefixes, f.i. in case of port number:

{ 0/6 => jump chain1, 0/5 => jump chain2, 0/4 => continue}

becomes:

{ 0-1023 => jump chain1, 1024-2047 => jump chain2, 2048-4095 => continue}

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/src/meta.c b/src/meta.c
index f06a2fbd..849acd15 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -61,6 +61,7 @@ static const struct datatype realm_type = {
 	.basetype	= &integer_type,
 	.print		= realm_type_print,
 	.parse		= realm_type_parse,
+	.flags		= DTYPE_F_PREFIX,
 };
 
 static void tchandle_type_print(const struct expr *expr)