proto: add support for meta templates

The following two patches will add two new meta expression types that are
used as dependencies in the inet table. To reuse the existing dependency
generation code, add a slightly hackish way to specify meta expressions
as payload dependencies.

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

diff --git a/include/proto.h b/include/proto.h
index de58d4cc2166488a0e4940202ecfc2f2d83f4384..6a280367801c6721c84eeab1313ac8d33d3fc597 100644 (file)
--- a/include/proto.h
+++ b/include/proto.h
@@ -2,6 +2,7 @@
 #define NFTABLES_PROTO_H
 
 #include <nftables.h>
+#include <linux/netfilter/nf_tables.h>
 
 /**
  * enum proto_bases - protocol bases
@@ -30,12 +31,14 @@ extern const char *proto_base_tokens[];
  * @dtype:     data type of the header field
  * @offset:    offset of the header field from base
  * @len:       length of header field
+ * @meta_key:  special case: meta expression key
  */
 struct proto_hdr_template {
        const char                      *token;
        const struct datatype           *dtype;
        uint16_t                        offset;
        uint16_t                        len;
+       enum nft_meta_keys              meta_key;
 };
 
 #define PROTO_HDR_TEMPLATE(__token, __dtype,  __offset, __len)         \
@@ -46,6 +49,14 @@ struct proto_hdr_template {
                .len            = (__len),                              \
        }
 
+#define PROTO_META_TEMPLATE(__token, __dtype, __key, __len)            \
+       {                                                               \
+               .token          = (__token),                            \
+               .dtype          = (__dtype),                            \
+               .meta_key       = (__key),                              \
+               .len            = (__len),                              \
+       }
+
 #define PROTO_UPPER_MAX                16
 #define PROTO_HDRS_MAX         20
 

diff --git a/src/payload.c b/src/payload.c
index 0ef3c791acb09abca13127e473f40615a025aaec..04a3455e38f0d7fc692109e8dadb6e8527a293c9 100644 (file)
--- a/src/payload.c
+++ b/src/payload.c
@@ -187,7 +187,11 @@ int payload_gen_dependency(struct eval_ctx *ctx, const struct expr *expr,
                                  desc->name, expr->payload.desc->name);
 
        tmpl = &desc->templates[desc->protocol_key];
-       left = payload_expr_alloc(&expr->location, desc, desc->protocol_key);
+       if (tmpl->meta_key)
+               left = meta_expr_alloc(&expr->location, tmpl->meta_key);
+       else
+               left = payload_expr_alloc(&expr->location, desc, desc->protocol_key);
+
        right = constant_expr_alloc(&expr->location, tmpl->dtype,
                                    BYTEORDER_HOST_ENDIAN,
                                    tmpl->len, &protocol);