src: Allow goto and jump to a variable

This patch introduces the use of nft input files variables in 'jump' and 'goto'
statements, e.g.

define dest = ber

add table ip foo
add chain ip foo bar {type filter hook input priority 0;}
add chain ip foo ber
add rule ip foo ber counter
add rule ip foo bar jump $dest

table ip foo {
        chain bar {
                type filter hook input priority filter; policy accept;
                jump ber
        }

        chain ber {
                counter packets 71 bytes 6664
        }
}

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 20 insertions, 1 deletions

diff --git a/src/datatype.c b/src/datatype.c
index 10f185bc..1d5ed6f7 100644
--- a/src/datatype.c
+++ b/src/datatype.c
@@ -309,11 +309,22 @@ static void verdict_type_print(const struct expr *expr, struct output_ctx *octx)
 	}
 }
 
+static struct error_record *verdict_type_parse(const struct expr *sym,
+					       struct expr **res)
+{
+	*res = constant_expr_alloc(&sym->location, &string_type,
+				   BYTEORDER_HOST_ENDIAN,
+				   (strlen(sym->identifier) + 1) * BITS_PER_BYTE,
+				   sym->identifier);
+	return NULL;
+}
+
 const struct datatype verdict_type = {
 	.type		= TYPE_VERDICT,
 	.name		= "verdict",
 	.desc		= "netfilter verdict",
 	.print		= verdict_type_print,
+	.parse		= verdict_type_parse,
 };
 
 static const struct symbol_table nfproto_tbl = {
diff --git a/src/evaluate.c b/src/evaluate.c
index 83940378..55fb3b61 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1950,6 +1950,13 @@ static int stmt_evaluate_verdict(struct eval_ctx *ctx, struct stmt *stmt)
 		if (stmt->expr->chain != NULL) {
 			if (expr_evaluate(ctx, &stmt->expr->chain) < 0)
 				return -1;
+			if ((stmt->expr->chain->etype != EXPR_SYMBOL &&
+			    stmt->expr->chain->etype != EXPR_VALUE) ||
+			    stmt->expr->chain->symtype != SYMBOL_VALUE) {
+				return stmt_error(ctx, stmt,
+						  "invalid verdict chain expression %s\n",
+						  expr_name(stmt->expr->chain));
+			}
 		}
 		break;
 	case EXPR_MAP:
diff --git a/src/parser_bison.y b/src/parser_bison.y
index f2583ade..62e76fe6 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -3841,7 +3841,8 @@ verdict_expr		:	ACCEPT
 			}
 			;
 
-chain_expr		:	identifier
+chain_expr		:	variable_expr
+			|	identifier
 			{
 				$$ = constant_expr_alloc(&@$, &string_type,
 							 BYTEORDER_HOST_ENDIAN,