xref: /linux-6.15/include/uapi/linux/tcp.h (revision 9552f908)

/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the TCP protocol.
 *
 * Version:	@(#)tcp.h	1.0.2	04/28/93
 *
 * Author:	Fred N. van Kempen, <[email protected]>
 *
 *		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 _UAPI_LINUX_TCP_H
#define _UAPI_LINUX_TCP_H

#include <linux/types.h>
#include <asm/byteorder.h>
#include <linux/socket.h>

struct tcphdr {
	__be16	source;
	__be16	dest;
	__be32	seq;
	__be32	ack_seq;
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u16	ae:1,
		res1:3,
		doff:4,
		fin:1,
		syn:1,
		rst:1,
		psh:1,
		ack:1,
		urg:1,
		ece:1,
		cwr:1;
#elif defined(__BIG_ENDIAN_BITFIELD)
	__u16	doff:4,
		res1:3,
		ae:1,
		cwr:1,
		ece:1,
		urg:1,
		ack:1,
		psh:1,
		rst:1,
		syn:1,
		fin:1;
#else
#error	"Adjust your <asm/byteorder.h> defines"
#endif
	__be16	window;
	__sum16	check;
	__be16	urg_ptr;
};

/*
 *	The union cast uses a gcc extension to avoid aliasing problems
 *  (union is compatible to any of its members)
 *  This means this part of the code is -fstrict-aliasing safe now.
 */
union tcp_word_hdr {
	struct tcphdr hdr;
	__be32        words[5];
};

#define tcp_flag_word(tp) (((union tcp_word_hdr *)(tp))->words[3])

enum {
	TCP_FLAG_AE  = __constant_cpu_to_be32(0x01000000),
	TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
	TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
	TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
	TCP_FLAG_ACK = __constant_cpu_to_be32(0x00100000),
	TCP_FLAG_PSH = __constant_cpu_to_be32(0x00080000),
	TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
	TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
	TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
	TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0E000000),
	TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
};

/*
 * TCP general constants
 */
#define TCP_MSS_DEFAULT		 536U	/* IPv4 (RFC1122, RFC2581) */
#define TCP_MSS_DESIRED		1220U	/* IPv6 (tunneled), EDNS0 (RFC3226) */

/* TCP socket options */
#define TCP_NODELAY		1	/* Turn off Nagle's algorithm. */
#define TCP_MAXSEG		2	/* Limit MSS */
#define TCP_CORK		3	/* Never send partially complete segments */
#define TCP_KEEPIDLE		4	/* Start keeplives after this period */
#define TCP_KEEPINTVL		5	/* Interval between keepalives */
#define TCP_KEEPCNT		6	/* Number of keepalives before death */
#define TCP_SYNCNT		7	/* Number of SYN retransmits */
#define TCP_LINGER2		8	/* Life time of orphaned FIN-WAIT-2 state */
#define TCP_DEFER_ACCEPT	9	/* Wake up listener only when data arrive */
#define TCP_WINDOW_CLAMP	10	/* Bound advertised window */
#define TCP_INFO		11	/* Information about this connection. */
#define TCP_QUICKACK		12	/* Block/reenable quick acks */
#define TCP_CONGESTION		13	/* Congestion control algorithm */
#define TCP_MD5SIG		14	/* TCP MD5 Signature (RFC2385) */
#define TCP_THIN_LINEAR_TIMEOUTS 16	/* Use linear timeouts for thin streams*/
#define TCP_THIN_DUPACK		17	/* Fast retrans. after 1 dupack */
#define TCP_USER_TIMEOUT	18	/* How long for loss retry before timeout */
#define TCP_REPAIR		19	/* TCP sock is under repair right now */
#define TCP_REPAIR_QUEUE	20
#define TCP_QUEUE_SEQ		21
#define TCP_REPAIR_OPTIONS	22
#define TCP_FASTOPEN		23	/* Enable FastOpen on listeners */
#define TCP_TIMESTAMP		24
#define TCP_NOTSENT_LOWAT	25	/* limit number of unsent bytes in write queue */
#define TCP_CC_INFO		26	/* Get Congestion Control (optional) info */
#define TCP_SAVE_SYN		27	/* Record SYN headers for new connections */
#define TCP_SAVED_SYN		28	/* Get SYN headers recorded for connection */
#define TCP_REPAIR_WINDOW	29	/* Get/set window parameters */
#define TCP_FASTOPEN_CONNECT	30	/* Attempt FastOpen with connect */
#define TCP_ULP			31	/* Attach a ULP to a TCP connection */
#define TCP_MD5SIG_EXT		32	/* TCP MD5 Signature with extensions */
#define TCP_FASTOPEN_KEY	33	/* Set the key for Fast Open (cookie) */
#define TCP_FASTOPEN_NO_COOKIE	34	/* Enable TFO without a TFO cookie */
#define TCP_ZEROCOPY_RECEIVE	35
#define TCP_INQ			36	/* Notify bytes available to read as a cmsg on read */

#define TCP_CM_INQ		TCP_INQ

#define TCP_TX_DELAY		37	/* delay outgoing packets by XX usec */

#define TCP_AO_ADD_KEY		38	/* Add/Set MKT */
#define TCP_AO_DEL_KEY		39	/* Delete MKT */
#define TCP_AO_INFO		40	/* Set/list TCP-AO per-socket options */
#define TCP_AO_GET_KEYS		41	/* List MKT(s) */
#define TCP_AO_REPAIR		42	/* Get/Set SNEs and ISNs */

#define TCP_IS_MPTCP		43	/* Is MPTCP being used? */
#define TCP_RTO_MAX_MS		44	/* max rto time in ms */
#define TCP_RTO_MIN_US		45	/* min rto time in us */
#define TCP_DELACK_MAX_US	46	/* max delayed ack time in us */

#define TCP_REPAIR_ON		1
#define TCP_REPAIR_OFF		0
#define TCP_REPAIR_OFF_NO_WP	-1	/* Turn off without window probes */

struct tcp_repair_opt {
	__u32	opt_code;
	__u32	opt_val;
};

struct tcp_repair_window {
	__u32	snd_wl1;
	__u32	snd_wnd;
	__u32	max_window;

	__u32	rcv_wnd;
	__u32	rcv_wup;
};

enum {
	TCP_NO_QUEUE,
	TCP_RECV_QUEUE,
	TCP_SEND_QUEUE,
	TCP_QUEUES_NR,
};

/* why fastopen failed from client perspective */
enum tcp_fastopen_client_fail {
	TFO_STATUS_UNSPEC, /* catch-all */
	TFO_COOKIE_UNAVAILABLE, /* if not in TFO_CLIENT_NO_COOKIE mode */
	TFO_DATA_NOT_ACKED, /* SYN-ACK did not ack SYN data */
	TFO_SYN_RETRANSMITTED, /* SYN-ACK did not ack SYN data after timeout */
};

/* for TCP_INFO socket option */
#define TCPI_OPT_TIMESTAMPS	1
#define TCPI_OPT_SACK		2
#define TCPI_OPT_WSCALE		4
#define TCPI_OPT_ECN		8 /* ECN was negociated at TCP session init */
#define TCPI_OPT_ECN_SEEN	16 /* we received at least one packet with ECT */
#define TCPI_OPT_SYN_DATA	32 /* SYN-ACK acked data in SYN sent or rcvd */
#define TCPI_OPT_USEC_TS	64 /* usec timestamps */

/*
 * Sender's congestion state indicating normal or abnormal situations
 * in the last round of packets sent. The state is driven by the ACK
 * information and timer events.
 */
enum tcp_ca_state {
	/*
	 * Nothing bad has been observed recently.
	 * No apparent reordering, packet loss, or ECN marks.
	 */
	TCP_CA_Open = 0,
#define TCPF_CA_Open	(1<<TCP_CA_Open)
	/*
	 * The sender enters disordered state when it has received DUPACKs or
	 * SACKs in the last round of packets sent. This could be due to packet
	 * loss or reordering but needs further information to confirm packets
	 * have been lost.
	 */
	TCP_CA_Disorder = 1,
#define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
	/*
	 * The sender enters Congestion Window Reduction (CWR) state when it
	 * has received ACKs with ECN-ECE marks, or has experienced congestion
	 * or packet discard on the sender host (e.g. qdisc).
	 */
	TCP_CA_CWR = 2,
#define TCPF_CA_CWR	(1<<TCP_CA_CWR)
	/*
	 * The sender is in fast recovery and retransmitting lost packets,
	 * typically triggered by ACK events.
	 */
	TCP_CA_Recovery = 3,
#define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
	/*
	 * The sender is in loss recovery triggered by retransmission timeout.
	 */
	TCP_CA_Loss = 4
#define TCPF_CA_Loss	(1<<TCP_CA_Loss)
};

struct tcp_info {
	__u8	tcpi_state;
	__u8	tcpi_ca_state;
	__u8	tcpi_retransmits;
	__u8	tcpi_probes;
	__u8	tcpi_backoff;
	__u8	tcpi_options;
	__u8	tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
	__u8	tcpi_delivery_rate_app_limited:1, tcpi_fastopen_client_fail:2;

	__u32	tcpi_rto;
	__u32	tcpi_ato;
	__u32	tcpi_snd_mss;
	__u32	tcpi_rcv_mss;

	__u32	tcpi_unacked;
	__u32	tcpi_sacked;
	__u32	tcpi_lost;
	__u32	tcpi_retrans;
	__u32	tcpi_fackets;

	/* Times. */
	__u32	tcpi_last_data_sent;
	__u32	tcpi_last_ack_sent;     /* Not remembered, sorry. */
	__u32	tcpi_last_data_recv;
	__u32	tcpi_last_ack_recv;

	/* Metrics. */
	__u32	tcpi_pmtu;
	__u32	tcpi_rcv_ssthresh;
	__u32	tcpi_rtt;
	__u32	tcpi_rttvar;
	__u32	tcpi_snd_ssthresh;
	__u32	tcpi_snd_cwnd;
	__u32	tcpi_advmss;
	__u32	tcpi_reordering;

	__u32	tcpi_rcv_rtt;
	__u32	tcpi_rcv_space;

	__u32	tcpi_total_retrans;

	__u64	tcpi_pacing_rate;
	__u64	tcpi_max_pacing_rate;
	__u64	tcpi_bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
	__u64	tcpi_bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived */
	__u32	tcpi_segs_out;	     /* RFC4898 tcpEStatsPerfSegsOut */
	__u32	tcpi_segs_in;	     /* RFC4898 tcpEStatsPerfSegsIn */

	__u32	tcpi_notsent_bytes;
	__u32	tcpi_min_rtt;
	__u32	tcpi_data_segs_in;	/* RFC4898 tcpEStatsDataSegsIn */
	__u32	tcpi_data_segs_out;	/* RFC4898 tcpEStatsDataSegsOut */

	__u64   tcpi_delivery_rate;

	__u64	tcpi_busy_time;      /* Time (usec) busy sending data */
	__u64	tcpi_rwnd_limited;   /* Time (usec) limited by receive window */
	__u64	tcpi_sndbuf_limited; /* Time (usec) limited by send buffer */

	__u32	tcpi_delivered;
	__u32	tcpi_delivered_ce;

	__u64	tcpi_bytes_sent;     /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
	__u64	tcpi_bytes_retrans;  /* RFC4898 tcpEStatsPerfOctetsRetrans */
	__u32	tcpi_dsack_dups;     /* RFC4898 tcpEStatsStackDSACKDups */
	__u32	tcpi_reord_seen;     /* reordering events seen */

	__u32	tcpi_rcv_ooopack;    /* Out-of-order packets received */

	__u32	tcpi_snd_wnd;	     /* peer's advertised receive window after
				      * scaling (bytes)
				      */
	__u32	tcpi_rcv_wnd;	     /* local advertised receive window after
				      * scaling (bytes)
				      */

	__u32   tcpi_rehash;         /* PLB or timeout triggered rehash attempts */

	__u16	tcpi_total_rto;	/* Total number of RTO timeouts, including
				 * SYN/SYN-ACK and recurring timeouts.
				 */
	__u16	tcpi_total_rto_recoveries;	/* Total number of RTO
						 * recoveries, including any
						 * unfinished recovery.
						 */
	__u32	tcpi_total_rto_time;	/* Total time spent in RTO recoveries
					 * in milliseconds, including any
					 * unfinished recovery.
					 */
};

/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
enum {
	TCP_NLA_PAD,
	TCP_NLA_BUSY,		/* Time (usec) busy sending data */
	TCP_NLA_RWND_LIMITED,	/* Time (usec) limited by receive window */
	TCP_NLA_SNDBUF_LIMITED,	/* Time (usec) limited by send buffer */
	TCP_NLA_DATA_SEGS_OUT,	/* Data pkts sent including retransmission */
	TCP_NLA_TOTAL_RETRANS,	/* Data pkts retransmitted */
	TCP_NLA_PACING_RATE,    /* Pacing rate in bytes per second */
	TCP_NLA_DELIVERY_RATE,  /* Delivery rate in bytes per second */
	TCP_NLA_SND_CWND,       /* Sending congestion window */
	TCP_NLA_REORDERING,     /* Reordering metric */
	TCP_NLA_MIN_RTT,        /* minimum RTT */
	TCP_NLA_RECUR_RETRANS,  /* Recurring retransmits for the current pkt */
	TCP_NLA_DELIVERY_RATE_APP_LMT, /* delivery rate application limited ? */
	TCP_NLA_SNDQ_SIZE,	/* Data (bytes) pending in send queue */
	TCP_NLA_CA_STATE,	/* ca_state of socket */
	TCP_NLA_SND_SSTHRESH,	/* Slow start size threshold */
	TCP_NLA_DELIVERED,	/* Data pkts delivered incl. out-of-order */
	TCP_NLA_DELIVERED_CE,	/* Like above but only ones w/ CE marks */
	TCP_NLA_BYTES_SENT,	/* Data bytes sent including retransmission */
	TCP_NLA_BYTES_RETRANS,	/* Data bytes retransmitted */
	TCP_NLA_DSACK_DUPS,	/* DSACK blocks received */
	TCP_NLA_REORD_SEEN,	/* reordering events seen */
	TCP_NLA_SRTT,		/* smoothed RTT in usecs */
	TCP_NLA_TIMEOUT_REHASH, /* Timeout-triggered rehash attempts */
	TCP_NLA_BYTES_NOTSENT,	/* Bytes in write queue not yet sent */
	TCP_NLA_EDT,		/* Earliest departure time (CLOCK_MONOTONIC) */
	TCP_NLA_TTL,		/* TTL or hop limit of a packet received */
	TCP_NLA_REHASH,         /* PLB and timeout triggered rehash attempts */
};

/* for TCP_MD5SIG socket option */
#define TCP_MD5SIG_MAXKEYLEN	80

/* tcp_md5sig extension flags for TCP_MD5SIG_EXT */
#define TCP_MD5SIG_FLAG_PREFIX		0x1	/* address prefix length */
#define TCP_MD5SIG_FLAG_IFINDEX		0x2	/* ifindex set */

struct tcp_md5sig {
	struct __kernel_sockaddr_storage tcpm_addr;	/* address associated */
	__u8	tcpm_flags;				/* extension flags */
	__u8	tcpm_prefixlen;				/* address prefix */
	__u16	tcpm_keylen;				/* key length */
	int	tcpm_ifindex;				/* device index for scope */
	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];		/* key (binary) */
};

/* INET_DIAG_MD5SIG */
struct tcp_diag_md5sig {
	__u8	tcpm_family;
	__u8	tcpm_prefixlen;
	__u16	tcpm_keylen;
	__be32	tcpm_addr[4];
	__u8	tcpm_key[TCP_MD5SIG_MAXKEYLEN];
};

#define TCP_AO_MAXKEYLEN	80

#define TCP_AO_KEYF_IFINDEX	(1 << 0)	/* L3 ifindex for VRF */
#define TCP_AO_KEYF_EXCLUDE_OPT	(1 << 1)	/* "Indicates whether TCP
						 *  options other than TCP-AO
						 *  are included in the MAC
						 *  calculation"
						 */

struct tcp_ao_add { /* setsockopt(TCP_AO_ADD_KEY) */
	struct __kernel_sockaddr_storage addr;	/* peer's address for the key */
	char	alg_name[64];		/* crypto hash algorithm to use */
	__s32	ifindex;		/* L3 dev index for VRF */
	__u32   set_current	:1,	/* set key as Current_key at once */
		set_rnext	:1,	/* request it from peer with RNext_key */
		reserved	:30;	/* must be 0 */
	__u16	reserved2;		/* padding, must be 0 */
	__u8	prefix;			/* peer's address prefix */
	__u8	sndid;			/* SendID for outgoing segments */
	__u8	rcvid;			/* RecvID to match for incoming seg */
	__u8	maclen;			/* length of authentication code (hash) */
	__u8	keyflags;		/* see TCP_AO_KEYF_ */
	__u8	keylen;			/* length of ::key */
	__u8	key[TCP_AO_MAXKEYLEN];
} __attribute__((aligned(8)));

struct tcp_ao_del { /* setsockopt(TCP_AO_DEL_KEY) */
	struct __kernel_sockaddr_storage addr;	/* peer's address for the key */
	__s32	ifindex;		/* L3 dev index for VRF */
	__u32   set_current	:1,	/* corresponding ::current_key */
		set_rnext	:1,	/* corresponding ::rnext */
		del_async	:1,	/* only valid for listen sockets */
		reserved	:29;	/* must be 0 */
	__u16	reserved2;		/* padding, must be 0 */
	__u8	prefix;			/* peer's address prefix */
	__u8	sndid;			/* SendID for outgoing segments */
	__u8	rcvid;			/* RecvID to match for incoming seg */
	__u8	current_key;		/* KeyID to set as Current_key */
	__u8	rnext;			/* KeyID to set as Rnext_key */
	__u8	keyflags;		/* see TCP_AO_KEYF_ */
} __attribute__((aligned(8)));

struct tcp_ao_info_opt { /* setsockopt(TCP_AO_INFO), getsockopt(TCP_AO_INFO) */
	/* Here 'in' is for setsockopt(), 'out' is for getsockopt() */
	__u32   set_current	:1,	/* in/out: corresponding ::current_key */
		set_rnext	:1,	/* in/out: corresponding ::rnext */
		ao_required	:1,	/* in/out: don't accept non-AO connects */
		set_counters	:1,	/* in: set/clear ::pkt_* counters */
		accept_icmps	:1,	/* in/out: accept incoming ICMPs */
		reserved	:27;	/* must be 0 */
	__u16	reserved2;		/* padding, must be 0 */
	__u8	current_key;		/* in/out: KeyID of Current_key */
	__u8	rnext;			/* in/out: keyid of RNext_key */
	__u64	pkt_good;		/* in/out: verified segments */
	__u64	pkt_bad;		/* in/out: failed verification */
	__u64	pkt_key_not_found;	/* in/out: could not find a key to verify */
	__u64	pkt_ao_required;	/* in/out: segments missing TCP-AO sign */
	__u64	pkt_dropped_icmp;	/* in/out: ICMPs that were ignored */
} __attribute__((aligned(8)));

struct tcp_ao_getsockopt { /* getsockopt(TCP_AO_GET_KEYS) */
	struct __kernel_sockaddr_storage addr;	/* in/out: dump keys for peer
						 * with this address/prefix
						 */
	char	alg_name[64];		/* out: crypto hash algorithm */
	__u8	key[TCP_AO_MAXKEYLEN];
	__u32	nkeys;			/* in: size of the userspace buffer
					 * @optval, measured in @optlen - the
					 * sizeof(struct tcp_ao_getsockopt)
					 * out: number of keys that matched
					 */
	__u16   is_current	:1,	/* in: match and dump Current_key,
					 * out: the dumped key is Current_key
					 */

		is_rnext	:1,	/* in: match and dump RNext_key,
					 * out: the dumped key is RNext_key
					 */
		get_all		:1,	/* in: dump all keys */
		reserved	:13;	/* padding, must be 0 */
	__u8	sndid;			/* in/out: dump keys with SendID */
	__u8	rcvid;			/* in/out: dump keys with RecvID */
	__u8	prefix;			/* in/out: dump keys with address/prefix */
	__u8	maclen;			/* out: key's length of authentication
					 * code (hash)
					 */
	__u8	keyflags;		/* in/out: see TCP_AO_KEYF_ */
	__u8	keylen;			/* out: length of ::key */
	__s32	ifindex;		/* in/out: L3 dev index for VRF */
	__u64	pkt_good;		/* out: verified segments */
	__u64	pkt_bad;		/* out: segments that failed verification */
} __attribute__((aligned(8)));

struct tcp_ao_repair { /* {s,g}etsockopt(TCP_AO_REPAIR) */
	__be32			snt_isn;
	__be32			rcv_isn;
	__u32			snd_sne;
	__u32			rcv_sne;
} __attribute__((aligned(8)));

/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */

#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1
struct tcp_zerocopy_receive {
	__u64 address;		/* in: address of mapping */
	__u32 length;		/* in/out: number of bytes to map/mapped */
	__u32 recv_skip_hint;	/* out: amount of bytes to skip */
	__u32 inq; /* out: amount of bytes in read queue */
	__s32 err; /* out: socket error */
	__u64 copybuf_address;	/* in: copybuf address (small reads) */
	__s32 copybuf_len; /* in/out: copybuf bytes avail/used or error */
	__u32 flags; /* in: flags */
	__u64 msg_control; /* ancillary data */
	__u64 msg_controllen;
	__u32 msg_flags;
	__u32 reserved; /* set to 0 for now */
};
#endif /* _UAPI_LINUX_TCP_H */