src: add EXPR_RANGE_VALUE expression and use it

set element with range takes 4 instances of struct expr:

  EXPR_SET_ELEM -> EXPR_RANGE -> (2) EXPR_VALUE

where EXPR_RANGE represents two references to struct expr with constant
value.

This new EXPR_RANGE_VALUE trims it down to two expressions:

  EXPR_SET_ELEM -> EXPR_RANGE_VALUE

with two direct low and high values that represent the range:

  struct {
      mpz_t low;
      mpz_t high;
  };

this two new direct values in struct expr do not modify its size.

setelem_expr_to_range() translates EXPR_RANGE to EXPR_RANGE_VALUE, this
conversion happens at a later stage.

constant_range_expr_print() translates this structure to constant values
to reuse the existing datatype_print() which relies in singleton values.

The automerge routine has been updated to use EXPR_RANGE_VALUE.

This requires a follow up patch to rework the conversion from range
expression to singleton element to provide a noticeable memory
consumption reduction.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/expression.h b/include/expression.h
index 877887ff..f2b45250 100644
--- a/include/expression.h
+++ b/include/expression.h
@@ -48,6 +48,7 @@
  * @EXPR_XFRM		XFRM (ipsec) expression
  * @EXPR_SET_ELEM_CATCHALL catchall element expression
  * @EXPR_FLAGCMP	flagcmp expression
+ * @EXPR_RANGE_VALUE	constant range expression
  */
 enum expr_types {
 	EXPR_INVALID,
@@ -80,6 +81,7 @@ enum expr_types {
 	EXPR_XFRM,
 	EXPR_SET_ELEM_CATCHALL,
 	EXPR_FLAGCMP,
+	EXPR_RANGE_VALUE,
 
 	EXPR_MAX = EXPR_FLAGCMP
 };
@@ -279,6 +281,11 @@ struct expr {
 			mpz_t			value;
 		};
 		struct {
+			/* EXPR_RANGE_VALUE */
+			mpz_t			low;
+			mpz_t			high;
+		} range;
+		struct {
 			/* EXPR_PREFIX */
 			struct expr		*prefix;
 			unsigned int		prefix_len;
@@ -473,6 +480,12 @@ extern struct expr *constant_expr_join(const struct expr *e1,
 				       const struct expr *e2);
 extern struct expr *constant_expr_splice(struct expr *expr, unsigned int len);
 
+extern struct expr *constant_range_expr_alloc(const struct location *loc,
+					      const struct datatype *dtype,
+					      enum byteorder byteorder,
+					      unsigned int len,
+					      mpz_t low, mpz_t high);
+
 extern struct expr *flag_expr_alloc(const struct location *loc,
 				    const struct datatype *dtype,
 				    enum byteorder byteorder,