tools: ynl: user space helpers

Add "fixed" part of the user space Netlink Spec-based library.
This will get linked with the protocol implementations to form
a full API.

Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 237 insertions, 0 deletions

diff --git a/tools/net/ynl/lib/ynl.h b/tools/net/ynl/lib/ynl.h
new file mode 100644
index 000000000000..9eafa3552c16
--- /dev/null
+++ b/tools/net/ynl/lib/ynl.h
@@ -0,0 +1,237 @@
+// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
+#ifndef __YNL_C_H
+#define __YNL_C_H 1
+
+#include <stddef.h>
+#include <libmnl/libmnl.h>
+#include <linux/genetlink.h>
+#include <linux/types.h>
+
+struct mnl_socket;
+struct nlmsghdr;
+
+/*
+ * User facing code
+ */
+
+struct ynl_ntf_base_type;
+struct ynl_ntf_info;
+struct ynl_sock;
+
+enum ynl_error_code {
+	YNL_ERROR_NONE = 0,
+	__YNL_ERRNO_END = 4096,
+	YNL_ERROR_INTERNAL,
+	YNL_ERROR_EXPECT_ACK,
+	YNL_ERROR_EXPECT_MSG,
+	YNL_ERROR_UNEXPECT_MSG,
+	YNL_ERROR_ATTR_MISSING,
+	YNL_ERROR_ATTR_INVALID,
+	YNL_ERROR_UNKNOWN_NTF,
+	YNL_ERROR_INV_RESP,
+};
+
+/**
+ * struct ynl_error - error encountered by YNL
+ * @code:	errno (low values) or YNL error code (enum ynl_error_code)
+ * @attr_offs:	offset of bad attribute (for very advanced users)
+ * @msg:	error message
+ *
+ * Error information for when YNL operations fail.
+ * Users should interact with the err member of struct ynl_sock directly.
+ * The main exception to that rule is ynl_sock_create().
+ */
+struct ynl_error {
+	enum ynl_error_code code;
+	unsigned int attr_offs;
+	char msg[512];
+};
+
+/**
+ * struct ynl_family - YNL family info
+ * Family description generated by codegen. Pass to ynl_sock_create().
+ */
+struct ynl_family {
+/* private: */
+	const char *name;
+	const struct ynl_ntf_info *ntf_info;
+	unsigned int ntf_info_size;
+};
+
+/**
+ * struct ynl_sock - YNL wrapped netlink socket
+ * @err: YNL error descriptor, cleared on every request.
+ */
+struct ynl_sock {
+	struct ynl_error err;
+
+/* private: */
+	const struct ynl_family *family;
+	struct mnl_socket *sock;
+	__u32 seq;
+	__u32 portid;
+	__u16 family_id;
+
+	unsigned int n_mcast_groups;
+	struct {
+		unsigned int id;
+		char name[GENL_NAMSIZ];
+	} *mcast_groups;
+
+	struct ynl_ntf_base_type *ntf_first;
+	struct ynl_ntf_base_type **ntf_last_next;
+
+	struct nlmsghdr *nlh;
+	struct ynl_policy_nest *req_policy;
+	unsigned char *tx_buf;
+	unsigned char *rx_buf;
+	unsigned char raw_buf[];
+};
+
+struct ynl_sock *
+ynl_sock_create(const struct ynl_family *yf, struct ynl_error *e);
+void ynl_sock_destroy(struct ynl_sock *ys);
+
+#define ynl_dump_foreach(dump, iter)					\
+	for (typeof(dump->obj) *iter = &dump->obj;			\
+	     !ynl_dump_obj_is_last(iter);				\
+	     iter = ynl_dump_obj_next(iter))
+
+int ynl_subscribe(struct ynl_sock *ys, const char *grp_name);
+int ynl_socket_get_fd(struct ynl_sock *ys);
+int ynl_ntf_check(struct ynl_sock *ys);
+
+/**
+ * ynl_has_ntf() - check if socket has *parsed* notifications
+ * @ys: active YNL socket
+ *
+ * Note that this does not take into account notifications sitting
+ * in netlink socket, just the notifications which have already been
+ * read and parsed (e.g. during a ynl_ntf_check() call).
+ */
+static inline bool ynl_has_ntf(struct ynl_sock *ys)
+{
+	return ys->ntf_last_next != &ys->ntf_first;
+}
+struct ynl_ntf_base_type *ynl_ntf_dequeue(struct ynl_sock *ys);
+
+void ynl_ntf_free(struct ynl_ntf_base_type *ntf);
+
+/*
+ * YNL internals / low level stuff
+ */
+
+/* Generic mnl helper code */
+
+enum ynl_policy_type {
+	YNL_PT_REJECT = 1,
+	YNL_PT_IGNORE,
+	YNL_PT_NEST,
+	YNL_PT_FLAG,
+	YNL_PT_BINARY,
+	YNL_PT_U8,
+	YNL_PT_U16,
+	YNL_PT_U32,
+	YNL_PT_U64,
+	YNL_PT_NUL_STR,
+};
+
+struct ynl_policy_attr {
+	enum ynl_policy_type type;
+	unsigned int len;
+	const char *name;
+	struct ynl_policy_nest *nest;
+};
+
+struct ynl_policy_nest {
+	unsigned int max_attr;
+	struct ynl_policy_attr *table;
+};
+
+struct ynl_parse_arg {
+	struct ynl_sock *ys;
+	struct ynl_policy_nest *rsp_policy;
+	void *data;
+};
+
+struct ynl_dump_list_type {
+	struct ynl_dump_list_type *next;
+	unsigned char data[] __attribute__ ((aligned (8)));
+};
+extern struct ynl_dump_list_type *YNL_LIST_END;
+
+static inline bool ynl_dump_obj_is_last(void *obj)
+{
+	unsigned long uptr = (unsigned long)obj;
+
+	uptr -= offsetof(struct ynl_dump_list_type, data);
+	return uptr == (unsigned long)YNL_LIST_END;
+}
+
+static inline void *ynl_dump_obj_next(void *obj)
+{
+	unsigned long uptr = (unsigned long)obj;
+	struct ynl_dump_list_type *list;
+
+	uptr -= offsetof(struct ynl_dump_list_type, data);
+	list = (void *)uptr;
+	uptr = (unsigned long)list->next;
+	uptr += offsetof(struct ynl_dump_list_type, data);
+
+	return (void *)uptr;
+}
+
+struct ynl_ntf_base_type {
+	__u16 family;
+	__u8 cmd;
+	struct ynl_ntf_base_type *next;
+	void (*free)(struct ynl_ntf_base_type *ntf);
+	unsigned char data[] __attribute__ ((aligned (8)));
+};
+
+extern mnl_cb_t ynl_cb_array[NLMSG_MIN_TYPE];
+
+struct nlmsghdr *
+ynl_gemsg_start_req(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version);
+struct nlmsghdr *
+ynl_gemsg_start_dump(struct ynl_sock *ys, __u32 id, __u8 cmd, __u8 version);
+
+int ynl_attr_validate(struct ynl_parse_arg *yarg, const struct nlattr *attr);
+
+int ynl_recv_ack(struct ynl_sock *ys, int ret);
+int ynl_cb_null(const struct nlmsghdr *nlh, void *data);
+
+/* YNL specific helpers used by the auto-generated code */
+
+struct ynl_req_state {
+	struct ynl_parse_arg yarg;
+	mnl_cb_t cb;
+	__u32 rsp_cmd;
+};
+
+struct ynl_dump_state {
+	struct ynl_sock *ys;
+	struct ynl_policy_nest *rsp_policy;
+	void *first;
+	struct ynl_dump_list_type *last;
+	size_t alloc_sz;
+	mnl_cb_t cb;
+	__u32 rsp_cmd;
+};
+
+struct ynl_ntf_info {
+	struct ynl_policy_nest *policy;
+	mnl_cb_t cb;
+	size_t alloc_sz;
+	void (*free)(struct ynl_ntf_base_type *ntf);
+};
+
+int ynl_exec(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
+	     struct ynl_req_state *yrs);
+int ynl_exec_dump(struct ynl_sock *ys, struct nlmsghdr *req_nlh,
+		  struct ynl_dump_state *yds);
+
+void ynl_error_unknown_notification(struct ynl_sock *ys, __u8 cmd);
+int ynl_error_parse(struct ynl_parse_arg *yarg, const char *msg);
+
+#endif