Re: [PATCH 1/3 nft] parser: get rid of multiton_expr from lhs relational expression

[Patrick McHardy <kaber@trash.net>]

On 29.12, Pablo Neira Ayuso wrote:
> The multiton_expr rule matches range, prefix and wildcard expressions
> which don't make sense from the non-constant lhs. This rule is there to
> handle the nat statement case, whose expression may be composed of
> address and port ranges (hence range expressions).

Its actually originates from set expressions. As long as we can still use
it there and can use bitwise and similar expressions for both sets and
maps this seems fine.

> To resolve this, this patch adds the stmt_expr rule to handle the
> possible occurrences of map, multiton and primary expressions from
> statements.
> 
> This results in more rules but it narrows down what we can find from
> expressions that are part of action statements.

I had a similar patch which simply split it up into lhs and rhs expressions.
Using stmt_expr seems a bit limited considering that we already use it for
other things than statements.


> 
> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
> ---
>  src/parser_bison.y | 54 ++++++++++++++++++++++++++++++++++++++++++++----------
>  1 file changed, 44 insertions(+), 10 deletions(-)
> 
> diff --git a/src/parser_bison.y b/src/parser_bison.y
> index d42bd2f..b49eadb 100644
> --- a/src/parser_bison.y
> +++ b/src/parser_bison.y
> @@ -486,6 +486,10 @@ static void location_update(struct location *loc, struct location *rhs, int n)
>  %destructor { expr_free($$); }	multiton_expr
>  %type <expr>			prefix_expr range_expr wildcard_expr
>  %destructor { expr_free($$); }	prefix_expr range_expr wildcard_expr
> +
> +%type <expr>			stmt_expr concat_stmt_expr map_stmt_expr
> +%destructor { expr_free($$); }	stmt_expr concat_stmt_expr map_stmt_expr
> +
>  %type <expr>			list_expr
>  %destructor { expr_free($$); }	list_expr
>  %type <expr>			concat_expr
> @@ -1577,20 +1581,51 @@ nat_stmt_alloc		:	SNAT
>  			}
>  			;
>  
> -nat_stmt_args		:	expr
> +concat_stmt_expr	:	primary_expr
> +			|	concat_stmt_expr	DOT	primary_expr
> +			{
> +				if ($$->ops->type != EXPR_CONCAT) {
> +					$$ = concat_expr_alloc(&@$);
> +					compound_expr_add($$, $1);
> +				} else {
> +					struct location rhs[] = {
> +						[1]	= @2,
> +						[2]	= @3,
> +					};
> +					location_update(&$3->location, rhs, 2);
> +
> +					$$ = $1;
> +					$$->location = @$;
> +				}
> +				compound_expr_add($$, $3);
> +			}
> +			;
> +
> +map_stmt_expr		:	concat_stmt_expr	MAP	rhs_expr
> +			{
> +				$$ = map_expr_alloc(&@$, $1, $3);
> +			}
> +			;
> +
> +stmt_expr		:	map_stmt_expr
> +			|	multiton_expr
> +			|	primary_expr
> +			;
> +
> +nat_stmt_args		:	stmt_expr
>  			{
>  				$<stmt>0->nat.addr = $1;
>  			}
> -			|	expr	COLON	expr
> +			|	stmt_expr	COLON	stmt_expr
>  			{
>  				$<stmt>0->nat.addr = $1;
>  				$<stmt>0->nat.proto = $3;
>  			}
> -			|	COLON	expr
> +			|	COLON		stmt_expr
>  			{
>  				$<stmt>0->nat.proto = $2;
>  			}
> -			|	nat_stmt_args	nf_nat_flags
> +			|       nat_stmt_args   nf_nat_flags
>  			{
>  				$<stmt>0->nat.flags = $2;
>  			}
> @@ -1614,7 +1649,7 @@ redir_stmt		:	redir_stmt_alloc	redir_stmt_arg
>  redir_stmt_alloc	:	REDIRECT	{ $$ = redir_stmt_alloc(&@$); }
>  			;
>  
> -redir_stmt_arg		:	TO	expr
> +redir_stmt_arg		:	TO	stmt_expr
>  			{
>  				$<stmt>0->redir.proto = $2;
>  			}
> @@ -1622,19 +1657,19 @@ redir_stmt_arg		:	TO	expr
>  			{
>  				$<stmt>0->redir.flags = $1;
>  			}
> -			|	TO	expr	nf_nat_flags
> +			|	TO	stmt_expr	nf_nat_flags
>  			{
>  				$<stmt>0->redir.proto = $2;
>  				$<stmt>0->redir.flags = $3;
>  			}
>  			;
>  
> -dup_stmt		:	DUP	TO	expr
> +dup_stmt		:	DUP	TO	stmt_expr
>  			{
>  				$$ = dup_stmt_alloc(&@$);
>  				$$->dup.to = $3;
>  			}
> -			|	DUP	TO	expr 	DEVICE	expr
> +			|	DUP	TO	stmt_expr 	DEVICE	stmt_expr
>  			{
>  				$$ = dup_stmt_alloc(&@$);
>  				$$->dup.to = $3;
> @@ -1671,7 +1706,7 @@ queue_stmt_args		:	queue_stmt_arg
>  			|	queue_stmt_args	queue_stmt_arg
>  			;
>  
> -queue_stmt_arg		:	QUEUENUM	expr
> +queue_stmt_arg		:	QUEUENUM	stmt_expr
>  			{
>  				$<stmt>0->queue.queue = $2;
>  			}
> @@ -1865,7 +1900,6 @@ map_expr		:	concat_expr	MAP	rhs_expr
>  			;
>  
>  expr			:	concat_expr
> -			|	multiton_expr
>  			|	set_expr
>  			|       map_expr
>  			;
> -- 
> 2.1.4
>