From 4e5e8066044f830407678c60b6b8b1c5aa21873b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jo=C3=A3o=20Valverde?= <j@v6e.pt>
Date: Thu, 14 Oct 2021 17:21:10 +0100
Subject: dfilter: Do not chain matches expressions

It is always an error to chain regexes using the logic for "le" and "eq".

  var matches "regex1" matches "regex2"
    => var matches "regex1" and "regex1" matches "regex2"

Before:
  Filter: tcp matches "abc$" matches "^cde"
  dftest: Neither "abc$" nor "^cde" are field or protocol names.

  Filter: "abc$" matches tcp matches "^cde"
  dftest: Neither "abc$" nor "tcp" are field or protocol names.

After:
  Filter: tcp matches "abc$" matches "^cde"
  dftest: "matches" was unexpected in this context.

  Filter: "abc$" matches tcp matches "^cde"
  dftest: "matches" was unexpected in this context.
---
 epan/dfilter/grammar.lemon | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/epan/dfilter/grammar.lemon b/epan/dfilter/grammar.lemon
index b2666710a2..d3dc79ea9c 100644
--- a/epan/dfilter/grammar.lemon
+++ b/epan/dfilter/grammar.lemon
@@ -76,9 +76,11 @@ any "error" symbols are shifted, if possible. */
 	}
 
 	switch(stnode_type_id(TOKEN)) {
-		case STTYPE_UNINITIALIZED:
+		case STTYPE_UNINITIALIZED: /* fall-through */
+		case STTYPE_UNPARSED:
 			if (stnode_token_value(TOKEN) != NULL)
-				dfilter_fail(dfw, "Syntax error near \"%s\".", stnode_token_value(TOKEN));
+				dfilter_fail(dfw, "\"%s\" was unexpected in this context.",
+						stnode_token_value(TOKEN));
 			else
 				dfilter_fail(dfw, "Syntax error.");
 			break;
@@ -90,10 +92,6 @@ any "error" symbols are shifted, if possible. */
 			dfilter_fail(dfw, "The character constant \"%s\" was unexpected in this context.",
 				(char *)stnode_data(TOKEN));
 			break;
-		case STTYPE_UNPARSED:
-			dfilter_fail(dfw, "\"%s\" was unexpected in this context.",
-				(char *)stnode_data(TOKEN));
-			break;
 		/* These aren't handed to use as terminal tokens from
 		   the scanner, so was can assert that we'll never
 		   see them here. */
@@ -274,7 +272,6 @@ rel_binop(O) ::= TEST_LT.	{ O = TEST_OP_LT; }
 rel_binop(O) ::= TEST_LE.	{ O = TEST_OP_LE; }
 rel_binop(O) ::= TEST_BITWISE_AND. { O = TEST_OP_BITWISE_AND; }
 rel_binop(O) ::= TEST_CONTAINS.	{ O = TEST_OP_CONTAINS; }
-rel_binop(O) ::= TEST_MATCHES.	{ O = TEST_OP_MATCHES; }
 
 /* Relational tests */
 relation_test(T) ::= entity(E) rel_binop(O) entity(F).
@@ -304,6 +301,13 @@ relation_test(T) ::= entity(E) rel_binop(O) relation_test(R).
 	sttype_test_set2(T, TEST_OP_AND, L, R);
 }
 
+/* "matches" does not chain with other relational tests. */ 
+relation_test(T) ::= entity(E) TEST_MATCHES entity(F).
+{
+	T = stnode_new(STTYPE_TEST, NULL, NULL);
+	sttype_test_set2(T, TEST_OP_MATCHES, E, F);
+}
+
 relation_test(T) ::= entity(E) TEST_IN LBRACE set_node_list(L) RBRACE.
 {
 	stnode_t *S;
-- 
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