src: add "typeof" build/parse/print support

This patch adds two new expression operations to build and to parse the
userdata area that describe the set key and data typeof definitions.

For maps, the grammar enforces either

"type data_type : data_type" or or "typeof expression : expression".

Check both key and data for valid user typeof info first.
If they check out, flag set->key_typeof_valid as true and use it for
printing the key info.

This patch comes with initial support for using payload expressions
with the 'typeof' keyword, followup patches will add support for other
expressions as well.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 75 insertions, 0 deletions

diff --git a/src/payload.c b/src/payload.c
index 3576400b..29242537 100644
--- a/src/payload.c
+++ b/src/payload.c
@@ -105,6 +105,79 @@ static void payload_expr_pctx_update(struct proto_ctx *ctx,
 	proto_ctx_update(ctx, desc->base, &expr->location, desc);
 }
 
+#define NFTNL_UDATA_SET_KEY_PAYLOAD_DESC 0
+#define NFTNL_UDATA_SET_KEY_PAYLOAD_TYPE 1
+#define NFTNL_UDATA_SET_KEY_PAYLOAD_MAX 2
+
+static unsigned int expr_payload_type(const struct proto_desc *desc,
+				      const struct proto_hdr_template *tmpl)
+{
+	return (unsigned int)(tmpl - &desc->templates[0]);
+}
+
+static int payload_expr_build_udata(struct nftnl_udata_buf *udbuf,
+				    const struct expr *expr)
+{
+	const struct proto_hdr_template *tmpl = expr->payload.tmpl;
+	const struct proto_desc *desc = expr->payload.desc;
+	unsigned int type = expr_payload_type(desc, tmpl);
+
+	nftnl_udata_put_u32(udbuf, NFTNL_UDATA_SET_KEY_PAYLOAD_DESC, desc->id);
+	nftnl_udata_put_u32(udbuf, NFTNL_UDATA_SET_KEY_PAYLOAD_TYPE, type);
+
+	return 0;
+}
+
+static const struct proto_desc *find_proto_desc(const struct nftnl_udata *ud)
+{
+	return proto_find_desc(nftnl_udata_get_u32(ud));
+}
+
+static int payload_parse_udata(const struct nftnl_udata *attr, void *data)
+{
+	const struct nftnl_udata **ud = data;
+	uint8_t type = nftnl_udata_type(attr);
+	uint8_t len = nftnl_udata_len(attr);
+
+	switch (type) {
+	case NFTNL_UDATA_SET_KEY_PAYLOAD_DESC:
+	case NFTNL_UDATA_SET_KEY_PAYLOAD_TYPE:
+		if (len != sizeof(uint32_t))
+			return -1;
+		break;
+	default:
+		return 0;
+	}
+
+	ud[type] = attr;
+	return 0;
+}
+
+static struct expr *payload_expr_parse_udata(const struct nftnl_udata *attr)
+{
+	const struct nftnl_udata *ud[NFTNL_UDATA_SET_KEY_PAYLOAD_MAX + 1] = {};
+	const struct proto_desc *desc;
+	unsigned int type;
+	int err;
+
+	err = nftnl_udata_parse(nftnl_udata_get(attr), nftnl_udata_len(attr),
+				payload_parse_udata, ud);
+	if (err < 0)
+		return NULL;
+
+	if (!ud[NFTNL_UDATA_SET_KEY_PAYLOAD_DESC] ||
+	    !ud[NFTNL_UDATA_SET_KEY_PAYLOAD_TYPE])
+		return NULL;
+
+	desc = find_proto_desc(ud[NFTNL_UDATA_SET_KEY_PAYLOAD_DESC]);
+	if (!desc)
+		return NULL;
+
+	type = nftnl_udata_get_u32(ud[NFTNL_UDATA_SET_KEY_PAYLOAD_TYPE]);
+
+	return payload_expr_alloc(&internal_location, desc, type);
+}
+
 const struct expr_ops payload_expr_ops = {
 	.type		= EXPR_PAYLOAD,
 	.name		= "payload",
@@ -113,6 +186,8 @@ const struct expr_ops payload_expr_ops = {
 	.cmp		= payload_expr_cmp,
 	.clone		= payload_expr_clone,
 	.pctx_update	= payload_expr_pctx_update,
+	.build_udata	= payload_expr_build_udata,
+	.parse_udata	= payload_expr_parse_udata,
 };
 
 /*