ct expr: protocol context updates and dynamic typing

Include the protocols defined through relational ct expressions in the
protocol context and use the protocol context to dynamically determine
the types of network and transport layer ct expression types.

Before:

$ nft filter output ct proto-dst ssh
<cmdline>:1:28-30: Error: Can't parse symbolic invalid expressions
filter output ct proto-dst ssh
                           ^^^
$ nft filter output ip protocol tcp ct proto-dst ssh
<cmdline>:1:44-46: Error: Can't parse symbolic invalid expressions
filter output ip protocol tcp ct proto-dst ssh
                                           ^^^
$ nft filter output ct protocol tcp ct proto-dst ssh
<cmdline>:1:44-46: Error: Can't parse symbolic invalid expressions
filter output ct protocol tcp ct proto-dst ssh
                                           ^^^
After:

$ nft filter output ct proto-dst ssh
<cmdline>:1:28-30: Error: Can't parse symbolic invalid expressions
filter output ct proto-dst ssh
                           ^^^
$ nft filter output ip protocol tcp ct proto-dst ssh
$ nft filter output ct protocol tcp ct proto-dst ssh

Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 58 insertions, 0 deletions

diff --git a/src/ct.c b/src/ct.c
index e5ca593c..b8f76325 100644
--- a/src/ct.c
+++ b/src/ct.c
@@ -23,6 +23,7 @@
 #include <expression.h>
 #include <datatype.h>
 #include <ct.h>
+#include <gmputil.h>
 #include <utils.h>
 
 static const struct symbol_table ct_state_tbl = {
@@ -139,11 +140,32 @@ static void ct_expr_clone(struct expr *new, const struct expr *expr)
 	new->ct.key = expr->ct.key;
 }
 
+static void ct_expr_pctx_update(struct proto_ctx *ctx, const struct expr *expr)
+{
+	const struct expr *left = expr->left, *right = expr->right;
+	const struct proto_desc *base, *desc;
+
+	assert(expr->op == OP_EQ);
+
+	switch (left->ct.key) {
+	case NFT_CT_PROTOCOL:
+		base = ctx->protocol[PROTO_BASE_NETWORK_HDR].desc;
+		desc = proto_find_upper(base, mpz_get_uint32(right->value));
+
+		proto_ctx_update(ctx, PROTO_BASE_TRANSPORT_HDR,
+				 &expr->location, desc);
+		break;
+	default:
+		break;
+	}
+}
+
 static const struct expr_ops ct_expr_ops = {
 	.type		= EXPR_CT,
 	.name		= "ct",
 	.print		= ct_expr_print,
 	.clone		= ct_expr_clone,
+	.pctx_update	= ct_expr_pctx_update,
 };
 
 struct expr *ct_expr_alloc(const struct location *loc, enum nft_ct_keys key)
@@ -154,9 +176,45 @@ struct expr *ct_expr_alloc(const struct location *loc, enum nft_ct_keys key)
 	expr = expr_alloc(loc, &ct_expr_ops, tmpl->dtype,
 			  tmpl->byteorder, tmpl->len);
 	expr->ct.key = key;
+
+	switch (key) {
+	case NFT_CT_PROTOCOL:
+		expr->flags = EXPR_F_PROTOCOL;
+		break;
+	default:
+		break;
+	}
+
 	return expr;
 }
 
+void ct_expr_update_type(struct proto_ctx *ctx, struct expr *expr)
+{
+	const struct proto_desc *desc;
+
+	switch (expr->ct.key) {
+	case NFT_CT_SRC:
+	case NFT_CT_DST:
+		desc = ctx->protocol[PROTO_BASE_NETWORK_HDR].desc;
+		if (desc == &proto_ip)
+			expr->dtype = &ipaddr_type;
+		else if (desc == &proto_ip6)
+			expr->dtype = &ip6addr_type;
+
+		expr->len = expr->dtype->size;
+		break;
+	case NFT_CT_PROTO_SRC:
+	case NFT_CT_PROTO_DST:
+		desc = ctx->protocol[PROTO_BASE_TRANSPORT_HDR].desc;
+		if (desc == NULL)
+			break;
+		expr->dtype = &inet_service_type;
+		break;
+	default:
+		break;
+	}
+}
+
 static void __init ct_init(void)
 {
 	datatype_register(&ct_state_type);