This is useful to allow a construct such as:
| tcp flags & (syn|fin) == (syn|fin)
Before, only the parentheses on the left side were allowed, but via a
quite funny path through the parser:
* expr might be a concat_expr
* concat_expr might be a basic_expr
* basic_expr is an inclusive_or_expr
* inclusive_or_expr might be an exclusive_or_expr
* exclusive_or_expr might be an and_expr
* and_expr might be 'and_expr AMPERSAND shift_expr'
-> here we eliminate 'flags &' in above statement
* shift_expr might be a primary_expr
* primary_expr might be '( basic_expr )'
Commit a3e60492a684b ("parser: restrict relational rhs expression
recursion") introduced rhs_expr to disallow recursion on RHS, so just
reverting that change for relational_expr is a no go. Allowing rhs_expr
to be '( rhs_expr )' though seems way too intrusive to me since it's
being used in all kinds of places, so this patch is the safest way to
allow the above I could come up with.
Signed-off-by: Phil Sutter <phil@xxxxxx>
---
src/parser_bison.y | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 91955c187f3f0..73a0eda9a5d87 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -2254,6 +2254,10 @@ relational_expr : expr /* implicit */ rhs_expr
{
$$ = relational_expr_alloc(&@2, $2, $1, $3);
}
+ | expr relational_op '(' rhs_expr ')'
+ {
+ $$ = relational_expr_alloc(&@2, $2, $1, $4);
+ }
;
list_rhs_expr : basic_rhs_expr COMMA basic_rhs_expr
--
2.10.0
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