libnftables: Implement JSON output support

Although technically there already is support for JSON output via 'nft
export json' command, it is hardly useable since it exports all the gory
details of nftables VM. Also, libnftables has no control over what is
exported since the content comes directly from libnftnl.

Instead, implement JSON format support for regular 'nft list' commands.

Signed-off-by: Phil Sutter <phil@nwl.cc>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 161 insertions, 0 deletions

diff --git a/include/json.h b/include/json.h
new file mode 100644
index 00000000..579bd5df
--- /dev/null
+++ b/include/json.h
@@ -0,0 +1,161 @@
+#ifndef NFTABLES_JSON_H
+#define NFTABLES_JSON_H
+
+struct chain;
+struct cmd;
+struct expr;
+struct netlink_ctx;
+struct rule;
+struct set;
+struct stmt;
+struct symbol_table;
+struct table;
+
+#ifdef HAVE_LIBJANSSON
+
+#include <jansson.h>
+
+json_t *binop_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *relational_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *range_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *meta_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *payload_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *ct_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *concat_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *set_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *set_ref_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *set_elem_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *prefix_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *list_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *unary_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *mapping_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *map_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *exthdr_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *verdict_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *rt_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *numgen_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *hash_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *fib_expr_json(const struct expr *expr, struct output_ctx *octx);
+json_t *constant_expr_json(const struct expr *expr, struct output_ctx *octx);
+
+json_t *integer_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *string_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *boolean_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *inet_protocol_type_json(const struct expr *expr,
+				struct output_ctx *octx);
+json_t *inet_service_type_json(const struct expr *expr,
+			       struct output_ctx *octx);
+json_t *mark_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *devgroup_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *ct_label_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *time_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *uid_type_json(const struct expr *expr, struct output_ctx *octx);
+json_t *gid_type_json(const struct expr *expr, struct output_ctx *octx);
+
+json_t *expr_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *payload_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *exthdr_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *quota_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *ct_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *limit_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *fwd_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *notrack_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *dup_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *meta_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *nat_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *reject_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *counter_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *set_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *log_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *objref_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *meter_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *queue_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+json_t *verdict_stmt_json(const struct stmt *stmt, struct output_ctx *octx);
+
+int do_command_list_json(struct netlink_ctx *ctx, struct cmd *cmd);
+
+#else /* ! HAVE_LIBJANSSON */
+
+typedef void json_t;
+
+#define JSON_PRINT_STUB(name, arg1_t, arg2_t) \
+static inline json_t *name##_json(arg1_t arg1, arg2_t arg2) { return NULL; }
+
+#define EXPR_PRINT_STUB(name) \
+	JSON_PRINT_STUB(name, const struct expr *, struct output_ctx *)
+#define STMT_PRINT_STUB(name) \
+	JSON_PRINT_STUB(name##_stmt, const struct stmt *, struct output_ctx *)
+
+EXPR_PRINT_STUB(binop_expr)
+EXPR_PRINT_STUB(relational_expr)
+EXPR_PRINT_STUB(range_expr)
+EXPR_PRINT_STUB(meta_expr)
+EXPR_PRINT_STUB(payload_expr)
+EXPR_PRINT_STUB(ct_expr)
+EXPR_PRINT_STUB(concat_expr)
+EXPR_PRINT_STUB(set_expr)
+EXPR_PRINT_STUB(set_ref_expr)
+EXPR_PRINT_STUB(set_elem_expr)
+EXPR_PRINT_STUB(prefix_expr)
+EXPR_PRINT_STUB(list_expr)
+EXPR_PRINT_STUB(unary_expr)
+EXPR_PRINT_STUB(mapping_expr)
+EXPR_PRINT_STUB(map_expr)
+EXPR_PRINT_STUB(exthdr_expr)
+EXPR_PRINT_STUB(verdict_expr)
+EXPR_PRINT_STUB(rt_expr)
+EXPR_PRINT_STUB(numgen_expr)
+EXPR_PRINT_STUB(hash_expr)
+EXPR_PRINT_STUB(fib_expr)
+EXPR_PRINT_STUB(constant_expr)
+
+EXPR_PRINT_STUB(integer_type)
+EXPR_PRINT_STUB(string_type)
+EXPR_PRINT_STUB(boolean_type)
+EXPR_PRINT_STUB(inet_protocol_type)
+EXPR_PRINT_STUB(inet_service_type)
+EXPR_PRINT_STUB(mark_type)
+EXPR_PRINT_STUB(devgroup_type)
+EXPR_PRINT_STUB(ct_label_type)
+EXPR_PRINT_STUB(time_type)
+EXPR_PRINT_STUB(uid_type)
+EXPR_PRINT_STUB(gid_type)
+
+STMT_PRINT_STUB(expr)
+STMT_PRINT_STUB(payload)
+STMT_PRINT_STUB(exthdr)
+STMT_PRINT_STUB(quota)
+STMT_PRINT_STUB(ct)
+STMT_PRINT_STUB(limit)
+STMT_PRINT_STUB(fwd)
+STMT_PRINT_STUB(notrack)
+STMT_PRINT_STUB(dup)
+STMT_PRINT_STUB(meta)
+STMT_PRINT_STUB(nat)
+STMT_PRINT_STUB(reject)
+STMT_PRINT_STUB(counter)
+STMT_PRINT_STUB(set)
+STMT_PRINT_STUB(log)
+STMT_PRINT_STUB(objref)
+STMT_PRINT_STUB(meter)
+STMT_PRINT_STUB(queue)
+STMT_PRINT_STUB(verdict)
+
+#undef STMT_PRINT_STUB
+#undef EXPR_PRINT_STUB
+#undef JSON_PRINT_STUB
+
+static inline json_t *symbolic_constant_json(const struct symbol_table *tbl,
+					     const struct expr *expr)
+{
+	return NULL;
+}
+
+static inline int do_command_list_json(struct netlink_ctx *ctx, struct cmd *cmd)
+{
+	return -1;
+}
+
+#endif /* HAVE_LIBJANSSON */
+
+#endif /* NFTABLES_JSON_H */