src: add auto-dependencies for ipv4 icmp

The ICMP header has field values that are only exist
for certain types.

Mark the icmp proto 'type' field as a nextheader field
and add a new th description to store the icmp type
dependency.  This can later be re-used for other protocol
dependend definitions such as mptcp options -- which are all share the
same tcp option number and have a special 4 bit marker inside the
mptcp option space that tells how the remaining option looks like.

Signed-off-by: Florian Westphal <fw@strlen.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/payload.h b/include/payload.h
index a914d239..7bbb19b9 100644
--- a/include/payload.h
+++ b/include/payload.h
@@ -15,6 +15,9 @@ struct eval_ctx;
 struct stmt;
 extern int payload_gen_dependency(struct eval_ctx *ctx, const struct expr *expr,
 				  struct stmt **res);
+extern int payload_gen_icmp_dependency(struct eval_ctx *ctx,
+				       const struct expr *expr,
+				       struct stmt **res);
 extern int exthdr_gen_dependency(struct eval_ctx *ctx, const struct expr *expr,
 				 const struct proto_desc *dependency,
 				 enum proto_bases pb, struct stmt **res);