datatype: add hint error handler

If user provides a symbol that cannot be parsed and the datatype provides
an error handler, provide a hint through the misspell infrastructure.

For instance:

 # cat test.nft
 table ip x {
        map y {
                typeof ip saddr : verdict
                elements = { 1.2.3.4 : filter_server1 }
        }
 }
 # nft -f test.nft
 test.nft:4:26-39: Error: Could not parse netfilter verdict; did you mean `jump filter_server1'?
                 elements = { 1.2.3.4 : filter_server1 }
                                        ^^^^^^^^^^^^^^

While at it, normalize error to "Could not parse symbolic %s expression".

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

1 files changed, 1 insertions, 0 deletions

diff --git a/include/datatype.h b/include/datatype.h
index 391d6ac8..4b59790b 100644
--- a/include/datatype.h
+++ b/include/datatype.h
@@ -167,6 +167,7 @@ struct datatype {
 	struct error_record		*(*parse)(struct parse_ctx *ctx,
 						  const struct expr *sym,
 						  struct expr **res);
+	struct error_record		*(*err)(const struct expr *sym);
 	void				(*describe)(struct output_ctx *octx);
 	const struct symbol_table	*sym_tbl;
 	unsigned int			refcnt;