src: support for implicit chain bindings

This patch allows you to group rules in a subchain, e.g.

 table inet x {
        chain y {
                type filter hook input priority 0;
                tcp dport 22 jump {
                        ip saddr { 127.0.0.0/8, 172.23.0.0/16, 192.168.13.0/24 } accept
                        ip6 saddr ::1/128 accept;
                }
        }
 }

This also supports for the `goto' chain verdict.

This patch adds a new chain binding list to avoid a chain list lookup from the
delinearize path for the usual chains. This can be simplified later on with a
single hashtable per table for all chains.

From the shell, you have to use the explicit separator ';', in bash you
have to escape this:

 # nft add rule inet x y tcp dport 80 jump { ip saddr 127.0.0.1 accept\; ip6 saddr ::1 accept \; }

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

1 files changed, 45 insertions, 0 deletions

diff --git a/src/statement.c b/src/statement.c
index afedbba2..6fe8e9d9 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -15,6 +15,7 @@
 #include <inttypes.h>
 #include <string.h>
 #include <syslog.h>
+#include <rule.h>
 
 #include <arpa/inet.h>
 #include <linux/netfilter.h>
@@ -112,6 +113,50 @@ struct stmt *verdict_stmt_alloc(const struct location *loc, struct expr *expr)
 	return stmt;
 }
 
+static const char *chain_verdict(const struct expr *expr)
+{
+	switch (expr->verdict) {
+	case NFT_JUMP:
+		return "jump";
+	case NFT_GOTO:
+		return "goto";
+	default:
+		BUG("unknown chain verdict");
+	}
+}
+
+static void chain_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
+{
+	nft_print(octx, "%s {\n", chain_verdict(stmt->chain.expr));
+	chain_rules_print(stmt->chain.chain, octx, "\t");
+	nft_print(octx, "\t\t}");
+}
+
+static void chain_stmt_destroy(struct stmt *stmt)
+{
+	expr_free(stmt->chain.expr);
+}
+
+static const struct stmt_ops chain_stmt_ops = {
+	.type		= STMT_CHAIN,
+	.name		= "chain",
+	.print		= chain_stmt_print,
+	.destroy	= chain_stmt_destroy,
+};
+
+struct stmt *chain_stmt_alloc(const struct location *loc, struct chain *chain,
+			      enum nft_verdicts verdict)
+{
+	struct stmt *stmt;
+
+	stmt = stmt_alloc(loc, &chain_stmt_ops);
+	stmt->chain.chain = chain;
+	stmt->chain.expr = verdict_expr_alloc(loc, verdict, NULL);
+	stmt->chain.expr->chain_id = chain->handle.chain_id;
+
+	return stmt;
+}
+
 static void meter_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
 {
 	unsigned int flags = octx->flags;