linux/include/linux/tcp.h
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   1/*
   2 * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3 *              operating system.  INET is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              Definitions for the TCP protocol.
   7 *
   8 * Version:     @(#)tcp.h       1.0.2   04/28/93
   9 *
  10 * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
  11 *
  12 *              This program is free software; you can redistribute it and/or
  13 *              modify it under the terms of the GNU General Public License
  14 *              as published by the Free Software Foundation; either version
  15 *              2 of the License, or (at your option) any later version.
  16 */
  17#ifndef _LINUX_TCP_H
  18#define _LINUX_TCP_H
  19
  20
  21#include <linux/skbuff.h>
  22#include <linux/dmaengine.h>
  23#include <net/sock.h>
  24#include <net/inet_connection_sock.h>
  25#include <net/inet_timewait_sock.h>
  26#include <uapi/linux/tcp.h>
  27
  28static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
  29{
  30        return (struct tcphdr *)skb_transport_header(skb);
  31}
  32
  33static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
  34{
  35        return tcp_hdr(skb)->doff * 4;
  36}
  37
  38static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
  39{
  40        return (struct tcphdr *)skb_inner_transport_header(skb);
  41}
  42
  43static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
  44{
  45        return inner_tcp_hdr(skb)->doff * 4;
  46}
  47
  48static inline unsigned int tcp_optlen(const struct sk_buff *skb)
  49{
  50        return (tcp_hdr(skb)->doff - 5) * 4;
  51}
  52
  53/* TCP Fast Open */
  54#define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
  55#define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
  56#define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
  57
  58/* TCP Fast Open Cookie as stored in memory */
  59struct tcp_fastopen_cookie {
  60        s8      len;
  61        u8      val[TCP_FASTOPEN_COOKIE_MAX];
  62};
  63
  64/* This defines a selective acknowledgement block. */
  65struct tcp_sack_block_wire {
  66        __be32  start_seq;
  67        __be32  end_seq;
  68};
  69
  70struct tcp_sack_block {
  71        u32     start_seq;
  72        u32     end_seq;
  73};
  74
  75/*These are used to set the sack_ok field in struct tcp_options_received */
  76#define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
  77#define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
  78#define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
  79
  80struct tcp_options_received {
  81/*      PAWS/RTTM data  */
  82        long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
  83        u32     ts_recent;      /* Time stamp to echo next              */
  84        u32     rcv_tsval;      /* Time stamp value                     */
  85        u32     rcv_tsecr;      /* Time stamp echo reply                */
  86        u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
  87                tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
  88                dsack : 1,      /* D-SACK is scheduled                  */
  89                wscale_ok : 1,  /* Wscale seen on SYN packet            */
  90                sack_ok : 4,    /* SACK seen on SYN packet              */
  91                snd_wscale : 4, /* Window scaling received from sender  */
  92                rcv_wscale : 4; /* Window scaling to send to receiver   */
  93        u8      cookie_plus:6,  /* bytes in authenticator/cookie option */
  94                cookie_out_never:1,
  95                cookie_in_always:1;
  96        u8      num_sacks;      /* Number of SACK blocks                */
  97        u16     user_mss;       /* mss requested by user in ioctl       */
  98        u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
  99};
 100
 101static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 102{
 103        rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
 104        rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
 105        rx_opt->cookie_plus = 0;
 106}
 107
 108/* This is the max number of SACKS that we'll generate and process. It's safe
 109 * to increase this, although since:
 110 *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 111 * only four options will fit in a standard TCP header */
 112#define TCP_NUM_SACKS 4
 113
 114struct tcp_cookie_values;
 115struct tcp_request_sock_ops;
 116
 117struct tcp_request_sock {
 118        struct inet_request_sock        req;
 119#ifdef CONFIG_TCP_MD5SIG
 120        /* Only used by TCP MD5 Signature so far. */
 121        const struct tcp_request_sock_ops *af_specific;
 122#endif
 123        struct sock                     *listener; /* needed for TFO */
 124        u32                             rcv_isn;
 125        u32                             snt_isn;
 126        u32                             snt_synack; /* synack sent time */
 127        u32                             rcv_nxt; /* the ack # by SYNACK. For
 128                                                  * FastOpen it's the seq#
 129                                                  * after data-in-SYN.
 130                                                  */
 131};
 132
 133static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 134{
 135        return (struct tcp_request_sock *)req;
 136}
 137
 138struct tcp_sock {
 139        /* inet_connection_sock has to be the first member of tcp_sock */
 140        struct inet_connection_sock     inet_conn;
 141        u16     tcp_header_len; /* Bytes of tcp header to send          */
 142        u16     xmit_size_goal_segs; /* Goal for segmenting output packets */
 143
 144/*
 145 *      Header prediction flags
 146 *      0x5?10 << 16 + snd_wnd in net byte order
 147 */
 148        __be32  pred_flags;
 149
 150/*
 151 *      RFC793 variables by their proper names. This means you can
 152 *      read the code and the spec side by side (and laugh ...)
 153 *      See RFC793 and RFC1122. The RFC writes these in capitals.
 154 */
 155        u32     rcv_nxt;        /* What we want to receive next         */
 156        u32     copied_seq;     /* Head of yet unread data              */
 157        u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 158        u32     snd_nxt;        /* Next sequence we send                */
 159
 160        u32     snd_una;        /* First byte we want an ack for        */
 161        u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 162        u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 163        u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 164
 165        u32     tsoffset;       /* timestamp offset */
 166
 167        struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
 168        unsigned long   tsq_flags;
 169
 170        /* Data for direct copy to user */
 171        struct {
 172                struct sk_buff_head     prequeue;
 173                struct task_struct      *task;
 174                struct iovec            *iov;
 175                int                     memory;
 176                int                     len;
 177#ifdef CONFIG_NET_DMA
 178                /* members for async copy */
 179                struct dma_chan         *dma_chan;
 180                int                     wakeup;
 181                struct dma_pinned_list  *pinned_list;
 182                dma_cookie_t            dma_cookie;
 183#endif
 184        } ucopy;
 185
 186        u32     snd_wl1;        /* Sequence for window update           */
 187        u32     snd_wnd;        /* The window we expect to receive      */
 188        u32     max_window;     /* Maximal window ever seen from peer   */
 189        u32     mss_cache;      /* Cached effective mss, not including SACKS */
 190
 191        u32     window_clamp;   /* Maximal window to advertise          */
 192        u32     rcv_ssthresh;   /* Current window clamp                 */
 193
 194        u32     frto_highmark;  /* snd_nxt when RTO occurred */
 195        u16     advmss;         /* Advertised MSS                       */
 196        u8      frto_counter;   /* Number of new acks after RTO */
 197        u8      nonagle     : 4,/* Disable Nagle algorithm?             */
 198                thin_lto    : 1,/* Use linear timeouts for thin streams */
 199                thin_dupack : 1,/* Fast retransmit on first dupack      */
 200                repair      : 1,
 201                unused      : 1;
 202        u8      repair_queue;
 203        u8      do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
 204                early_retrans_delayed:1, /* Delayed ER timer installed */
 205                syn_data:1,     /* SYN includes data */
 206                syn_fastopen:1, /* SYN includes Fast Open option */
 207                syn_data_acked:1;/* data in SYN is acked by SYN-ACK */
 208
 209/* RTT measurement */
 210        u32     srtt;           /* smoothed round trip time << 3        */
 211        u32     mdev;           /* medium deviation                     */
 212        u32     mdev_max;       /* maximal mdev for the last rtt period */
 213        u32     rttvar;         /* smoothed mdev_max                    */
 214        u32     rtt_seq;        /* sequence number to update rttvar     */
 215
 216        u32     packets_out;    /* Packets which are "in flight"        */
 217        u32     retrans_out;    /* Retransmitted packets out            */
 218
 219        u16     urg_data;       /* Saved octet of OOB data and control flags */
 220        u8      ecn_flags;      /* ECN status bits.                     */
 221        u8      reordering;     /* Packet reordering metric.            */
 222        u32     snd_up;         /* Urgent pointer               */
 223
 224        u8      keepalive_probes; /* num of allowed keep alive probes   */
 225/*
 226 *      Options received (usually on last packet, some only on SYN packets).
 227 */
 228        struct tcp_options_received rx_opt;
 229
 230/*
 231 *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 232 */
 233        u32     snd_ssthresh;   /* Slow start size threshold            */
 234        u32     snd_cwnd;       /* Sending congestion window            */
 235        u32     snd_cwnd_cnt;   /* Linear increase counter              */
 236        u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 237        u32     snd_cwnd_used;
 238        u32     snd_cwnd_stamp;
 239        u32     prior_cwnd;     /* Congestion window at start of Recovery. */
 240        u32     prr_delivered;  /* Number of newly delivered packets to
 241                                 * receiver in Recovery. */
 242        u32     prr_out;        /* Total number of pkts sent during Recovery. */
 243
 244        u32     rcv_wnd;        /* Current receiver window              */
 245        u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 246        u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 247        u32     lost_out;       /* Lost packets                 */
 248        u32     sacked_out;     /* SACK'd packets                       */
 249        u32     fackets_out;    /* FACK'd packets                       */
 250        u32     tso_deferred;
 251
 252        /* from STCP, retrans queue hinting */
 253        struct sk_buff* lost_skb_hint;
 254        struct sk_buff *scoreboard_skb_hint;
 255        struct sk_buff *retransmit_skb_hint;
 256
 257        struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
 258
 259        /* SACKs data, these 2 need to be together (see tcp_options_write) */
 260        struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 261        struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 262
 263        struct tcp_sack_block recv_sack_cache[4];
 264
 265        struct sk_buff *highest_sack;   /* skb just after the highest
 266                                         * skb with SACKed bit set
 267                                         * (validity guaranteed only if
 268                                         * sacked_out > 0)
 269                                         */
 270
 271        int     lost_cnt_hint;
 272        u32     retransmit_high;        /* L-bits may be on up to this seqno */
 273
 274        u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
 275
 276        u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 277        u32     high_seq;       /* snd_nxt at onset of congestion       */
 278
 279        u32     retrans_stamp;  /* Timestamp of the last retransmit,
 280                                 * also used in SYN-SENT to remember stamp of
 281                                 * the first SYN. */
 282        u32     undo_marker;    /* tracking retrans started here. */
 283        int     undo_retrans;   /* number of undoable retransmissions. */
 284        u32     total_retrans;  /* Total retransmits for entire connection */
 285
 286        u32     urg_seq;        /* Seq of received urgent pointer */
 287        unsigned int            keepalive_time;   /* time before keep alive takes place */
 288        unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 289
 290        int                     linger2;
 291
 292/* Receiver side RTT estimation */
 293        struct {
 294                u32     rtt;
 295                u32     seq;
 296                u32     time;
 297        } rcv_rtt_est;
 298
 299/* Receiver queue space */
 300        struct {
 301                int     space;
 302                u32     seq;
 303                u32     time;
 304        } rcvq_space;
 305
 306/* TCP-specific MTU probe information. */
 307        struct {
 308                u32               probe_seq_start;
 309                u32               probe_seq_end;
 310        } mtu_probe;
 311        u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
 312                           * while socket was owned by user.
 313                           */
 314
 315#ifdef CONFIG_TCP_MD5SIG
 316/* TCP AF-Specific parts; only used by MD5 Signature support so far */
 317        const struct tcp_sock_af_ops    *af_specific;
 318
 319/* TCP MD5 Signature Option information */
 320        struct tcp_md5sig_info  __rcu *md5sig_info;
 321#endif
 322
 323        /* When the cookie options are generated and exchanged, then this
 324         * object holds a reference to them (cookie_values->kref).  Also
 325         * contains related tcp_cookie_transactions fields.
 326         */
 327        struct tcp_cookie_values  *cookie_values;
 328
 329/* TCP fastopen related information */
 330        struct tcp_fastopen_request *fastopen_req;
 331        /* fastopen_rsk points to request_sock that resulted in this big
 332         * socket. Used to retransmit SYNACKs etc.
 333         */
 334        struct request_sock *fastopen_rsk;
 335};
 336
 337enum tsq_flags {
 338        TSQ_THROTTLED,
 339        TSQ_QUEUED,
 340        TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
 341        TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
 342        TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
 343        TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
 344                                    * tcp_v{4|6}_mtu_reduced()
 345                                    */
 346};
 347
 348static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 349{
 350        return (struct tcp_sock *)sk;
 351}
 352
 353struct tcp_timewait_sock {
 354        struct inet_timewait_sock tw_sk;
 355        u32                       tw_rcv_nxt;
 356        u32                       tw_snd_nxt;
 357        u32                       tw_rcv_wnd;
 358        u32                       tw_ts_offset;
 359        u32                       tw_ts_recent;
 360        long                      tw_ts_recent_stamp;
 361#ifdef CONFIG_TCP_MD5SIG
 362        struct tcp_md5sig_key     *tw_md5_key;
 363#endif
 364        /* Few sockets in timewait have cookies; in that case, then this
 365         * object holds a reference to them (tw_cookie_values->kref).
 366         */
 367        struct tcp_cookie_values  *tw_cookie_values;
 368};
 369
 370static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 371{
 372        return (struct tcp_timewait_sock *)sk;
 373}
 374
 375static inline bool tcp_passive_fastopen(const struct sock *sk)
 376{
 377        return (sk->sk_state == TCP_SYN_RECV &&
 378                tcp_sk(sk)->fastopen_rsk != NULL);
 379}
 380
 381static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
 382{
 383        return foc->len != -1;
 384}
 385
 386extern void tcp_sock_destruct(struct sock *sk);
 387
 388static inline int fastopen_init_queue(struct sock *sk, int backlog)
 389{
 390        struct request_sock_queue *queue =
 391            &inet_csk(sk)->icsk_accept_queue;
 392
 393        if (queue->fastopenq == NULL) {
 394                queue->fastopenq = kzalloc(
 395                    sizeof(struct fastopen_queue),
 396                    sk->sk_allocation);
 397                if (queue->fastopenq == NULL)
 398                        return -ENOMEM;
 399
 400                sk->sk_destruct = tcp_sock_destruct;
 401                spin_lock_init(&queue->fastopenq->lock);
 402        }
 403        queue->fastopenq->max_qlen = backlog;
 404        return 0;
 405}
 406
 407#endif  /* _LINUX_TCP_H */
 408
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