src: context tracking for multiple transport protocols

This patch extends the protocol context infrastructure to track multiple
transport protocols when they are specified from sets.

This removes errors like:

 "transport protocol mapping is only valid after transport protocol match"

when invoking:

 # nft add rule x z meta l4proto { tcp, udp } dnat to 1.1.1.1:80

This patch also catches conflicts like:

 # nft add rule x z ip protocol { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
 Error: conflicting protocols specified: udp vs. tcp
 add rule x z ip protocol { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
                                       ^^^^^^^^^
and:

 # nft add rule x z meta l4proto { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
 Error: conflicting protocols specified: udp vs. tcp
 add rule x z meta l4proto { tcp, udp } tcp dport 20 dnat to 1.1.1.1:80
                                        ^^^^^^^^^
Note that:

- the singleton protocol context tracker is left in place until the
  existing users are updated to use this new multiprotocol tracker.
  Moving forward, it would be good to consolidate things around this new
  multiprotocol context tracker infrastructure.

- link and network layers are not updated to use this infrastructure
  yet. The code that deals with vlan conflicts relies on forcing
  protocol context updates to the singleton protocol base.

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

1 files changed, 13 insertions, 3 deletions

diff --git a/src/expression.c b/src/expression.c
index fe529f98..87bd4d01 100644
--- a/src/expression.c
+++ b/src/expression.c
@@ -708,16 +708,26 @@ struct expr *relational_expr_alloc(const struct location *loc, enum ops op,
 void relational_expr_pctx_update(struct proto_ctx *ctx,
 				 const struct expr *expr)
 {
-	const struct expr *left = expr->left;
+	const struct expr *left = expr->left, *right = expr->right;
 	const struct expr_ops *ops;
+	const struct expr *i;
 
 	assert(expr->etype == EXPR_RELATIONAL);
 	assert(expr->op == OP_EQ || expr->op == OP_IMPLICIT);
 
 	ops = expr_ops(left);
 	if (ops->pctx_update &&
-	    (left->flags & EXPR_F_PROTOCOL))
-		ops->pctx_update(ctx, expr);
+	    (left->flags & EXPR_F_PROTOCOL)) {
+		if (expr_is_singleton(right))
+			ops->pctx_update(ctx, &expr->location, left, right);
+		else if (right->etype == EXPR_SET) {
+			list_for_each_entry(i, &right->expressions, list) {
+				if (i->etype == EXPR_SET_ELEM &&
+				    i->key->etype == EXPR_VALUE)
+					ops->pctx_update(ctx, &expr->location, left, i->key);
+			}
+		}
+	}
 }
 
 static void range_expr_print(const struct expr *expr, struct output_ctx *octx)