mptcp.h

/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
/*
 * Userspace API for Multipath TCP
 *
 * Author: Gregory Detal <gregory.detal@tessares.net>
 *	   Christoph Paasch <cpaasch@apple.com>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#ifndef _LINUX_MPTCP_H
#define _LINUX_MPTCP_H

#ifndef __KERNEL__
#include <netinet/in.h>		/* for sockaddr_in and sockaddr_in6	*/
#include <sys/socket.h>		/* for struct sockaddr			*/
#endif

#include <linux/in.h>		/* for sockaddr_in			*/
#include <linux/in6.h>		/* for sockaddr_in6			*/
#include <linux/socket.h>	/* for sockaddr_storage and sa_family	*/

/** NETLINK API **/

#define MPTCP_GENL_NAME		"mptcp"
#define MPTCP_GENL_EV_GRP_NAME	"mptcp_events"
#define MPTCP_GENL_CMD_GRP_NAME "mptcp_commands"
#define MPTCP_GENL_VER		0x1

/*
 * ATTR types defined for MPTCP
 */
enum {
	MPTCP_ATTR_UNSPEC = 0,

	MPTCP_ATTR_TOKEN,	/* u32 */
	MPTCP_ATTR_FAMILY,	/* u16 */
	MPTCP_ATTR_LOC_ID,	/* u8 */
	MPTCP_ATTR_REM_ID,	/* u8 */
	MPTCP_ATTR_SADDR4,	/* u32 */
	MPTCP_ATTR_SADDR6,	/* struct in6_addr */
	MPTCP_ATTR_DADDR4,	/* u32 */
	MPTCP_ATTR_DADDR6,	/* struct in6_addr */
	MPTCP_ATTR_SPORT,	/* u16 */
	MPTCP_ATTR_DPORT,	/* u16 */
	MPTCP_ATTR_BACKUP,	/* u8 */
	MPTCP_ATTR_ERROR,	/* u8 */
	MPTCP_ATTR_FLAGS,	/* u16 */
	MPTCP_ATTR_TIMEOUT,	/* u32 */
	MPTCP_ATTR_IF_IDX,	/* s32 */

	__MPTCP_ATTR_AFTER_LAST
};

#define MPTCP_ATTR_MAX (__MPTCP_ATTR_AFTER_LAST - 1)

/*
 * Events generated by MPTCP:
 *   - MPTCP_EVENT_CREATED: token, family, saddr4 | saddr6, daddr4 | daddr6,
 *                          sport, dport
 *       A new connection has been created. It is the good time to allocate
 *       memory and send ADD_ADDR if needed. Depending on the traffic-patterns
 *       it can take a long time until the MPTCP_EVENT_ESTABLISHED is sent.
 *
 *   - MPTCP_EVENT_ESTABLISHED: token, family, saddr4 | saddr6, daddr4 | daddr6,
 *                              sport, dport
 *       A connection is established (can start new subflows).
 *
 *   - MPTCP_EVENT_CLOSED: token
 *       A connection has stopped.
 *
 *   - MPTCP_EVENT_ANNOUNCED: token, rem_id, family, daddr4 | daddr6 [, dport]
 *       A new address has been announced by the peer.
 *
 *   - MPTCP_EVENT_REMOVED: token, rem_id
 *       An address has been lost by the peer.
 *
 *   - MPTCP_EVENT_SUB_ESTABLISHED: token, family, loc_id, rem_id,
 *                                  saddr4 | saddr6, daddr4 | daddr6, sport,
 *                                  dport, backup, if_idx [, error]
 *       A new subflow has been established. 'error' should not be set.
 *
 *   - MPTCP_EVENT_SUB_CLOSED: token, family, loc_id, rem_id, saddr4 | saddr6,
 *                             daddr4 | daddr6, sport, dport, backup, if_idx
 *                             [, error]
 *       A subflow has been closed. An error (copy of sk_err) could be set if an
 *       error has been detected for this subflow.
 *
 *   - MPTCP_EVENT_SUB_PRIORITY: token, family, loc_id, rem_id, saddr4 | saddr6,
 *                               daddr4 | daddr6, sport, dport, backup, if_idx
 *                               [, error]
 *       The priority of a subflow has changed. 'error' should not be set.
 *
 * Commands for MPTCP:
 *   - MPTCP_CMD_ANNOUNCE: token, loc_id, family, saddr4 | saddr6 [, sport]
 *       Announce a new address to the peer.
 *
 *   - MPTCP_CMD_REMOVE: token, loc_id
 *       Announce that an address has been lost to the peer.
 *
 *   - MPTCP_CMD_SUB_CREATE: token, family, loc_id, rem_id, daddr4 | daddr6,
 *                           dport [, saddr4 | saddr6, sport, backup, if_idx]
 *       Create a new subflow.
 *
 *   - MPTCP_CMD_SUB_DESTROY: token, family, saddr4 | saddr6, daddr4 | daddr6,
 *                            sport, dport
 *       Close a subflow.
 *
 *   - MPTCP_CMD_SUB_PRIORITY: token, family, saddr4 | saddr6, daddr4 | daddr6,
 *                             sport, dport, backup
 *       Change the priority of a subflow.
 *
 *   - MPTCP_CMD_SET_FILTER: flags
 *       Set the filter on events. Set MPTCPF_* flags to only receive specific
 *       events. Default is to receive all events.
 *
 *   - MPTCP_CMD_EXIST: token
 *       Check if this token is linked to an existing socket.
 */
enum {
	MPTCP_CMD_UNSPEC = 0,

	MPTCP_EVENT_CREATED,
	MPTCP_EVENT_ESTABLISHED,
	MPTCP_EVENT_CLOSED,

	MPTCP_CMD_ANNOUNCE,
	MPTCP_CMD_REMOVE,
	MPTCP_EVENT_ANNOUNCED,
	MPTCP_EVENT_REMOVED,

	MPTCP_CMD_SUB_CREATE,
	MPTCP_CMD_SUB_DESTROY,
	MPTCP_EVENT_SUB_ESTABLISHED,
	MPTCP_EVENT_SUB_CLOSED,

	MPTCP_CMD_SUB_PRIORITY,
	MPTCP_EVENT_SUB_PRIORITY,

	MPTCP_CMD_SET_FILTER,

	MPTCP_CMD_EXIST,

	__MPTCP_CMD_AFTER_LAST
};

#define MPTCP_CMD_MAX (__MPTCP_CMD_AFTER_LAST - 1)

enum {
	MPTCPF_EVENT_CREATED		= (1 << 1),
	MPTCPF_EVENT_ESTABLISHED	= (1 << 2),
	MPTCPF_EVENT_CLOSED		= (1 << 3),
	MPTCPF_EVENT_ANNOUNCED		= (1 << 4),
	MPTCPF_EVENT_REMOVED		= (1 << 5),
	MPTCPF_EVENT_SUB_ESTABLISHED	= (1 << 6),
	MPTCPF_EVENT_SUB_CLOSED		= (1 << 7),
	MPTCPF_EVENT_SUB_PRIORITY	= (1 << 8),
};

/** Upstream Linux compatibility **/

/* MPTCP socket options */
#define MPTCP_INFO_UPSTREAM	1
#define MPTCP_TCPINFO		2
#define MPTCP_SUBFLOW_ADDRS	3

#define MPTCP_INFO_FLAG_FALLBACK		_BITUL(0)
#define MPTCP_INFO_FLAG_REMOTE_KEY_RECEIVED	_BITUL(1)

struct mptcp_info_upstream {
	__u8	mptcpi_subflows;
	__u8	mptcpi_add_addr_signal;
	__u8	mptcpi_add_addr_accepted;
	__u8	mptcpi_subflows_max;
	__u8	mptcpi_add_addr_signal_max;
	__u8	mptcpi_add_addr_accepted_max;
	__u32	mptcpi_flags;
	__u32	mptcpi_token;
	__u64	mptcpi_write_seq;
	__u64	mptcpi_snd_una;
	__u64	mptcpi_rcv_nxt;
	__u8	mptcpi_local_addr_used;
	__u8	mptcpi_local_addr_max;
	__u8	mptcpi_csum_enabled;
};

struct mptcp_subflow_data {
	__u32		size_subflow_data;		/* size of this structure in userspace */
	__u32		num_subflows;			/* must be 0, set by kernel */
	__u32		size_kernel;			/* must be 0, set by kernel */
	__u32		size_user;			/* size of one element in data[] */
} __attribute__((aligned(8)));

struct mptcp_subflow_addrs {
	union {
		__kernel_sa_family_t sa_family;
		struct sockaddr sa_local;
		struct sockaddr_in sin_local;
		struct sockaddr_in6 sin6_local;
		struct __kernel_sockaddr_storage ss_local;
	};
	union {
		struct sockaddr sa_remote;
		struct sockaddr_in sin_remote;
		struct sockaddr_in6 sin6_remote;
		struct __kernel_sockaddr_storage ss_remote;
	};
};

#endif /* _LINUX_MPTCP_H */