/*
* 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, <waltje@uWalt.NL.Mugnet.ORG>
*
* 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_TCP_H
#define _LINUX_TCP_H
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/inet_connection_sock.h>
#include <net/inet_timewait_sock.h>
#include <uapi/linux/tcp.h>
static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
{
return (struct tcphdr *)skb_transport_header(skb);
}
static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
{
return tcp_hdr(skb)->doff * 4;
}
static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
{
return (struct tcphdr *)skb_inner_transport_header(skb);
}
static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
{
return inner_tcp_hdr(skb)->doff * 4;
}
static inline unsigned int tcp_optlen(const struct sk_buff *skb)
{
return (tcp_hdr(skb)->doff - 5) * 4;
}
/* TCP Fast Open */
#define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */
#define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */
/* TCP Fast Open Cookie as stored in memory */
struct tcp_fastopen_cookie {
s8 len;
u8 val[TCP_FASTOPEN_COOKIE_MAX];
bool exp; /* In RFC6994 experimental option format */
};
/* This defines a selective acknowledgement block. */
struct tcp_sack_block_wire {
__be32 start_seq;
__be32 end_seq;
};
struct tcp_sack_block {
u32 start_seq;
u32 end_seq;
};
/*These are used to set the sack_ok field in struct tcp_options_received */
#define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */
#define TCP_FACK_ENABLED (1 << 1) /*1 = FACK is enabled locally*/
#define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/
struct tcp_options_received {
/* PAWS/RTTM data */
long ts_recent_stamp;/* Time we stored ts_recent (for aging) */
u32 ts_recent; /* Time stamp to echo next */
u32 rcv_tsval; /* Time stamp value */
u32 rcv_tsecr; /* Time stamp echo reply */
u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */
tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */
dsack : 1, /* D-SACK is scheduled */
wscale_ok : 1, /* Wscale seen on SYN packet */
sack_ok : 4, /* SACK seen on SYN packet */
snd_wscale : 4, /* Window scaling received from sender */
rcv_wscale : 4; /* Window scaling to send to receiver */
u8 num_sacks; /* Number of SACK blocks */
u16 user_mss; /* mss requested by user in ioctl */
u16 mss_clamp; /* Maximal mss, negotiated at connection setup */
};
static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
{
rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
}
/* This is the max number of SACKS that we'll generate and process. It's safe
* to increase this, although since:
* size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
* only four options will fit in a standard TCP header */
#define TCP_NUM_SACKS 4
struct tcp_request_sock_ops;
struct tcp_request_sock {
struct inet_request_sock req;
const struct tcp_request_sock_ops *af_specific;
struct skb_mstamp snt_synack; /* first SYNACK sent time */
bool tfo_listener;
u32 txhash;
u32 rcv_isn;
u32 snt_isn;
u32 last_oow_ack_time; /* last SYNACK */
u32 rcv_nxt; /* the ack # by SYNACK. For
* FastOpen it's the seq#
* after data-in-SYN.
*/
};
static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
{
return (struct tcp_request_sock *)req;
}
struct tcp_sock {
/* inet_connection_sock has to be the first member of tcp_sock */
struct inet_connection_sock inet_conn;
u16 tcp_header_len; /* Bytes of tcp header to send */
u16 gso_segs; /* Max number of segs per GSO packet */
/*
* Header prediction flags
* 0x5?10 << 16 + snd_wnd in net byte order
*/
__be32 pred_flags;
/*
* RFC793 variables by their proper names. This means you can
* read the code and the spec side by side (and laugh ...)
* See RFC793 and RFC1122. The RFC writes these in capitals.
*/
u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
* sum(delta(rcv_nxt)), or how many bytes
* were acked.
*/
u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn
* total number of segments in.
*/
u32 rcv_nxt; /* What we want to receive next */
u32 copied_seq; /* Head of yet unread data */
u32 rcv_wup; /* rcv_nxt on last window update sent */
u32 snd_nxt; /* Next sequence we send */
u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut
* The total number of segments sent.
*/
u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked
* sum(delta(snd_una)), or how many bytes
* were acked.
*/
struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */
u32 snd_una; /* First byte we want an ack for */
u32 snd_sml; /* Last byte of the most recently transmitted small packet */
u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */
u32 lsndtime; /* timestamp of last sent data packet (for restart window) */
u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */
u32 tsoffset; /* timestamp offset */
struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
unsigned long tsq_flags;
/* Data for direct copy to user */
struct {
struct sk_buff_head prequeue;
struct task_struct *task;
struct msghdr *msg;
int memory;
int len;
} ucopy;
u32 snd_wl1; /* Sequence for window update */
u32 snd_wnd; /* The window we expect to receive */
u32 max_window; /* Maximal window ever seen from peer */
u32 mss_cache; /* Cached effective mss, not including SACKS */
u32 window_clamp; /* Maximal window to advertise */
u32 rcv_ssthresh; /* Current window clamp */
/* Information of the most recently (s)acked skb */
struct tcp_rack {
struct skb_mstamp mstamp; /* (Re)sent time of the skb */
u8 advanced; /* mstamp advanced since last lost marking */
u8 reord; /* reordering detected */
} rack;
u16 advmss; /* Advertised MSS */
u8 unused;
u8 nonagle : 4,/* Disable Nagle algorithm? */
thin_lto : 1,/* Use linear timeouts for thin streams */
thin_dupack : 1,/* Fast retransmit on first dupack */
repair : 1,
frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */
u8 repair_queue;
u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */
syn_data:1, /* SYN includes data */
syn_fastopen:1, /* SYN includes Fast Open option */
syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
save_syn:1, /* Save headers of SYN packet */
is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */
/* RTT measurement */
u32 srtt_us; /* smoothed round trip time << 3 in usecs */
u32 mdev_us; /* medium deviation */
u32 mdev_max_us; /* maximal mdev for the last rtt period */
u32 rttvar_us; /* smoothed mdev_max */
u32 rtt_seq; /* sequence number to update rttvar */
struct rtt_meas {
u32 rtt, ts; /* RTT in usec and sampling time in jiffies. */
} rtt_min[3];
u32 packets_out; /* Packets which are "in flight" */
u32 retrans_out; /* Retransmitted packets out */
u32 max_packets_out; /* max packets_out in last window */
u32 max_packets_seq; /* right edge of max_packets_out flight */
u16 urg_data; /* Saved octet of OOB data and control flags */
u8 ecn_flags; /* ECN status bits. */
u8 keepalive_probes; /* num of allowed keep alive probes */
u32 reordering; /* Packet reordering metric. */
u32 snd_up; /* Urgent pointer */
/*
* Options received (usually on last packet, some only on SYN packets).
*/
struct tcp_options_received rx_opt;
/*
* Slow start and congestion control (see also Nagle, and Karn & Partridge)
*/
u32 snd_ssthresh; /* Slow start size threshold */
u32 snd_cwnd; /* Sending congestion window */
u32 snd_cwnd_cnt; /* Linear increase counter */
u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
u32 snd_cwnd_used;
u32 snd_cwnd_stamp;
u32 prior_cwnd; /* Congestion window at start of Recovery. */
u32 prr_delivered; /* Number of newly delivered packets to
* receiver in Recovery. */
u32 prr_out; /* Total number of pkts sent during Recovery. */
u32 rcv_wnd; /* Current receiver window */
u32 write_seq; /* Tail(+1) of data held in tcp send buffer */
u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */
u32 pushed_seq; /* Last pushed seq, required to talk to windows */
u32 lost_out; /* Lost packets */
u32 sacked_out; /* SACK'd packets */
u32 fackets_out; /* FACK'd packets */
/* from STCP, retrans queue hinting */
struct sk_buff* lost_skb_hint;
struct sk_buff *retransmit_skb_hint;
/* OOO segments go in this list. Note that socket lock must be held,
* as we do not use sk_buff_head lock.
*/
struct sk_buff_head out_of_order_queue;
/* SACKs data, these 2 need to be together (see tcp_options_write) */
struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
struct tcp_sack_block recv_sack_cache[4];
struct sk_buff *highest_sack; /* skb just after the highest
* skb with SACKed bit set
* (validity guaranteed only if
* sacked_out > 0)
*/
int lost_cnt_hint;
u32 retransmit_high; /* L-bits may be on up to this seqno */
u32 prior_ssthresh; /* ssthresh saved at recovery start */
u32 high_seq; /* snd_nxt at onset of congestion */
u32 retrans_stamp; /* Timestamp of the last retransmit,
* also used in SYN-SENT to remember stamp of
* the first SYN. */
u32 undo_marker; /* snd_una upon a new recovery episode. */
int undo_retrans; /* number of undoable retransmissions. */
u32 total_retrans; /* Total retransmits for entire connection */
u32 urg_seq; /* Seq of received urgent pointer */
unsigned int keepalive_time; /* time before keep alive takes place */
unsigned int keepalive_intvl; /* time interval between keep alive probes */
int linger2;
/* Receiver side RTT estimation */
struct {
u32 rtt;
u32 seq;
u32 time;
} rcv_rtt_est;
/* Receiver queue space */
struct {
int space;
u32 seq;
u32 time;
} rcvq_space;
/* TCP-specific MTU probe information. */
struct {
u32 probe_seq_start;
u32 probe_seq_end;
} mtu_probe;
u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
* while socket was owned by user.
*/
#ifdef CONFIG_TCP_MD5SIG
/* TCP AF-Specific parts; only used by MD5 Signature support so far */
const struct tcp_sock_af_ops *af_specific;
/* TCP MD5 Signature Option information */
struct tcp_md5sig_info __rcu *md5sig_info;
#endif
/* TCP fastopen related information */
struct tcp_fastopen_request *fastopen_req;
/* fastopen_rsk points to request_sock that resulted in this big
* socket. Used to retransmit SYNACKs etc.
*/
struct request_sock *fastopen_rsk;
u32 *saved_syn;
};
enum tsq_flags {
TSQ_THROTTLED,
TSQ_QUEUED,
TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */
TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */
TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call
* tcp_v{4|6}_mtu_reduced()
*/
};
static inline struct tcp_sock *tcp_sk(const struct sock *sk)
{
return (struct tcp_sock *)sk;
}
struct tcp_timewait_sock {
struct inet_timewait_sock tw_sk;
#define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt
#define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt
u32 tw_rcv_wnd;
u32 tw_ts_offset;
u32 tw_ts_recent;
/* The time we sent the last out-of-window ACK: */
u32 tw_last_oow_ack_time;
long tw_ts_recent_stamp;
#ifdef CONFIG_TCP_MD5SIG
struct tcp_md5sig_key *tw_md5_key;
#endif
};
static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
{
return (struct tcp_timewait_sock *)sk;
}
static inline bool tcp_passive_fastopen(const struct sock *sk)
{
return (sk->sk_state == TCP_SYN_RECV &&
tcp_sk(sk)->fastopen_rsk != NULL);
}
static inline void fastopen_queue_tune(struct sock *sk, int backlog)
{
struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn);
queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn);
}
static inline void tcp_move_syn(struct tcp_sock *tp,
struct request_sock *req)
{
tp->saved_syn = req->saved_syn;
req->saved_syn = NULL;
}
static inline void tcp_saved_syn_free(struct tcp_sock *tp)
{
kfree(tp->saved_syn);
tp->saved_syn = NULL;
}
#endif /* _LINUX_TCP_H */
