include/linux/tcp.h

   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 #include <linux/types.h>
  21 #include <asm/byteorder.h>
  22 #include <linux/socket.h>
  23
  24 struct tcphdr {
  25         __be16  source;
  26         __be16  dest;
  27         __be32  seq;
  28         __be32  ack_seq;
  29 #if defined(__LITTLE_ENDIAN_BITFIELD)
  30         __u16   res1:4,
  31                 doff:4,
  32                 fin:1,
  33                 syn:1,
  34                 rst:1,
  35                 psh:1,
  36                 ack:1,
  37                 urg:1,
  38                 ece:1,
  39                 cwr:1;
  40 #elif defined(__BIG_ENDIAN_BITFIELD)
  41         __u16   doff:4,
  42                 res1:4,
  43                 cwr:1,
  44                 ece:1,
  45                 urg:1,
  46                 ack:1,
  47                 psh:1,
  48                 rst:1,
  49                 syn:1,
  50                 fin:1;
  51 #else
  52 #error  "Adjust your <asm/byteorder.h> defines"
  53 #endif
  54         __be16  window;
  55         __sum16 check;
  56         __be16  urg_ptr;
  57 };
  58
  59 /*
  60  *      The union cast uses a gcc extension to avoid aliasing problems
  61  *  (union is compatible to any of its members)
  62  *  This means this part of the code is -fstrict-aliasing safe now.
  63  */
  64 union tcp_word_hdr {
  65         struct tcphdr hdr;
  66         __be32            words[5];
  67 };
  68
  69 #define tcp_flag_word(tp) ( ((union tcp_word_hdr *)(tp))->words [3])
  70
  71 enum {
  72         TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
  73         TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
  74         TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
  75         TCP_FLAG_ACK = __constant_cpu_to_be32(0x00100000),
  76         TCP_FLAG_PSH = __constant_cpu_to_be32(0x00080000),
  77         TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
  78         TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
  79         TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
  80         TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000),
  81         TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
  82 };
  83
  84 /*
  85  * TCP general constants
  86  */
  87 #define TCP_MSS_DEFAULT          536U   /* IPv4 (RFC1122, RFC2581) */
  88 #define TCP_MSS_DESIRED         1220U   /* IPv6 (tunneled), EDNS0 (RFC3226) */
  89
  90 /* TCP socket options */
  91 #define TCP_NODELAY             1       /* Turn off Nagle's algorithm. */
  92 #define TCP_MAXSEG              2       /* Limit MSS */
  93 #define TCP_CORK                3       /* Never send partially complete segments */
  94 #define TCP_KEEPIDLE            4       /* Start keeplives after this period */
  95 #define TCP_KEEPINTVL           5       /* Interval between keepalives */
  96 #define TCP_KEEPCNT             6       /* Number of keepalives before death */
  97 #define TCP_SYNCNT              7       /* Number of SYN retransmits */
  98 #define TCP_LINGER2             8       /* Life time of orphaned FIN-WAIT-2 state */
  99 #define TCP_DEFER_ACCEPT        9       /* Wake up listener only when data arrive */
 100 #define TCP_WINDOW_CLAMP        10      /* Bound advertised window */
 101 #define TCP_INFO                11      /* Information about this connection. */
 102 #define TCP_QUICKACK            12      /* Block/reenable quick acks */
 103 #define TCP_CONGESTION          13      /* Congestion control algorithm */
 104 #define TCP_MD5SIG              14      /* TCP MD5 Signature (RFC2385) */
 105 #define TCP_COOKIE_TRANSACTIONS 15      /* TCP Cookie Transactions */
 106 #define TCP_THIN_LINEAR_TIMEOUTS 16      /* Use linear timeouts for thin streams*/
 107 #define TCP_THIN_DUPACK         17      /* Fast retrans. after 1 dupack */
 108 #define TCP_USER_TIMEOUT        18      /* How long for loss retry before timeout */
 109 #define TCP_REPAIR              19      /* TCP sock is under repair right now */
 110 #define TCP_REPAIR_QUEUE        20
 111 #define TCP_QUEUE_SEQ           21
 112 #define TCP_REPAIR_OPTIONS      22
 113 #define TCP_FASTOPEN            23      /* Enable FastOpen on listeners */
 114
 115 struct tcp_repair_opt {
 116         __u32   opt_code;
 117         __u32   opt_val;
 118 };
 119
 120 enum {
 121         TCP_NO_QUEUE,
 122         TCP_RECV_QUEUE,
 123         TCP_SEND_QUEUE,
 124         TCP_QUEUES_NR,
 125 };
 126
 127 /* for TCP_INFO socket option */
 128 #define TCPI_OPT_TIMESTAMPS     1
 129 #define TCPI_OPT_SACK           2
 130 #define TCPI_OPT_WSCALE         4
 131 #define TCPI_OPT_ECN            8 /* ECN was negociated at TCP session init */
 132 #define TCPI_OPT_ECN_SEEN       16 /* we received at least one packet with ECT */
 133
 134 enum tcp_ca_state {
 135         TCP_CA_Open = 0,
 136 #define TCPF_CA_Open    (1<<TCP_CA_Open)
 137         TCP_CA_Disorder = 1,
 138 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
 139         TCP_CA_CWR = 2,
 140 #define TCPF_CA_CWR     (1<<TCP_CA_CWR)
 141         TCP_CA_Recovery = 3,
 142 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
 143         TCP_CA_Loss = 4
 144 #define TCPF_CA_Loss    (1<<TCP_CA_Loss)
 145 };
 146
 147 struct tcp_info {
 148         __u8    tcpi_state;
 149         __u8    tcpi_ca_state;
 150         __u8    tcpi_retransmits;
 151         __u8    tcpi_probes;
 152         __u8    tcpi_backoff;
 153         __u8    tcpi_options;
 154         __u8    tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
 155
 156         __u32   tcpi_rto;
 157         __u32   tcpi_ato;
 158         __u32   tcpi_snd_mss;
 159         __u32   tcpi_rcv_mss;
 160
 161         __u32   tcpi_unacked;
 162         __u32   tcpi_sacked;
 163         __u32   tcpi_lost;
 164         __u32   tcpi_retrans;
 165         __u32   tcpi_fackets;
 166
 167         /* Times. */
 168         __u32   tcpi_last_data_sent;
 169         __u32   tcpi_last_ack_sent;     /* Not remembered, sorry. */
 170         __u32   tcpi_last_data_recv;
 171         __u32   tcpi_last_ack_recv;
 172
 173         /* Metrics. */
 174         __u32   tcpi_pmtu;
 175         __u32   tcpi_rcv_ssthresh;
 176         __u32   tcpi_rtt;
 177         __u32   tcpi_rttvar;
 178         __u32   tcpi_snd_ssthresh;
 179         __u32   tcpi_snd_cwnd;
 180         __u32   tcpi_advmss;
 181         __u32   tcpi_reordering;
 182
 183         __u32   tcpi_rcv_rtt;
 184         __u32   tcpi_rcv_space;
 185
 186         __u32   tcpi_total_retrans;
 187 };
 188
 189 /* for TCP_MD5SIG socket option */
 190 #define TCP_MD5SIG_MAXKEYLEN    80
 191
 192 struct tcp_md5sig {
 193         struct __kernel_sockaddr_storage tcpm_addr;     /* address associated */
 194         __u16   __tcpm_pad1;                            /* zero */
 195         __u16   tcpm_keylen;                            /* key length */
 196         __u32   __tcpm_pad2;                            /* zero */
 197         __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
 198 };
 199
 200 /* for TCP_COOKIE_TRANSACTIONS (TCPCT) socket option */
 201 #define TCP_COOKIE_MIN           8              /*  64-bits */
 202 #define TCP_COOKIE_MAX          16              /* 128-bits */
 203 #define TCP_COOKIE_PAIR_SIZE    (2*TCP_COOKIE_MAX)
 204
 205 /* Flags for both getsockopt and setsockopt */
 206 #define TCP_COOKIE_IN_ALWAYS    (1 << 0)        /* Discard SYN without cookie */
 207 #define TCP_COOKIE_OUT_NEVER    (1 << 1)        /* Prohibit outgoing cookies,
 208                                                  * supercedes everything. */
 209
 210 /* Flags for getsockopt */
 211 #define TCP_S_DATA_IN           (1 << 2)        /* Was data received? */
 212 #define TCP_S_DATA_OUT          (1 << 3)        /* Was data sent? */
 213
 214 /* TCP_COOKIE_TRANSACTIONS data */
 215 struct tcp_cookie_transactions {
 216         __u16   tcpct_flags;                    /* see above */
 217         __u8    __tcpct_pad1;                   /* zero */
 218         __u8    tcpct_cookie_desired;           /* bytes */
 219         __u16   tcpct_s_data_desired;           /* bytes of variable data */
 220         __u16   tcpct_used;                     /* bytes in value */
 221         __u8    tcpct_value[TCP_MSS_DEFAULT];
 222 };
 223
 224 #ifdef __KERNEL__
 225
 226 #include <linux/skbuff.h>
 227 #include <linux/dmaengine.h>
 228 #include <net/sock.h>
 229 #include <net/inet_connection_sock.h>
 230 #include <net/inet_timewait_sock.h>
 231
 232 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
 233 {
 234         return (struct tcphdr *)skb_transport_header(skb);
 235 }
 236
 237 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
 238 {
 239         return tcp_hdr(skb)->doff * 4;
 240 }
 241
 242 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 243 {
 244         return (tcp_hdr(skb)->doff - 5) * 4;
 245 }
 246
 247 /* TCP Fast Open */
 248 #define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
 249 #define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
 250 #define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
 251
 252 /* TCP Fast Open Cookie as stored in memory */
 253 struct tcp_fastopen_cookie {
 254         s8      len;
 255         u8      val[TCP_FASTOPEN_COOKIE_MAX];
 256 };
 257
 258 /* This defines a selective acknowledgement block. */
 259 struct tcp_sack_block_wire {
 260         __be32  start_seq;
 261         __be32  end_seq;
 262 };
 263
 264 struct tcp_sack_block {
 265         u32     start_seq;
 266         u32     end_seq;
 267 };
 268
 269 /*These are used to set the sack_ok field in struct tcp_options_received */
 270 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
 271 #define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
 272 #define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
 273
 274 struct tcp_options_received {
 275 /*      PAWS/RTTM data  */
 276         long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 277         u32     ts_recent;      /* Time stamp to echo next              */
 278         u32     rcv_tsval;      /* Time stamp value                     */
 279         u32     rcv_tsecr;      /* Time stamp echo reply                */
 280         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 281                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 282                 dsack : 1,      /* D-SACK is scheduled                  */
 283                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 284                 sack_ok : 4,    /* SACK seen on SYN packet              */
 285                 snd_wscale : 4, /* Window scaling received from sender  */
 286                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 287         u8      cookie_plus:6,  /* bytes in authenticator/cookie option */
 288                 cookie_out_never:1,
 289                 cookie_in_always:1;
 290         u8      num_sacks;      /* Number of SACK blocks                */
 291         u16     user_mss;       /* mss requested by user in ioctl       */
 292         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 293 };
 294
 295 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 296 {
 297         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
 298         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
 299         rx_opt->cookie_plus = 0;
 300 }
 301
 302 /* This is the max number of SACKS that we'll generate and process. It's safe
 303  * to increase this, although since:
 304  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 305  * only four options will fit in a standard TCP header */
 306 #define TCP_NUM_SACKS 4
 307
 308 struct tcp_cookie_values;
 309 struct tcp_request_sock_ops;
 310
 311 struct tcp_request_sock {
 312         struct inet_request_sock        req;
 313 #ifdef CONFIG_TCP_MD5SIG
 314         /* Only used by TCP MD5 Signature so far. */
 315         const struct tcp_request_sock_ops *af_specific;
 316 #endif
 317         struct sock                     *listener; /* needed for TFO */
 318         u32                             rcv_isn;
 319         u32                             snt_isn;
 320         u32                             snt_synack; /* synack sent time */
 321         u32                             rcv_nxt; /* the ack # by SYNACK. For
 322                                                   * FastOpen it's the seq#
 323                                                   * after data-in-SYN.
 324                                                   */
 325 };
 326
 327 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 328 {
 329         return (struct tcp_request_sock *)req;
 330 }
 331
 332 struct tcp_sock {
 333         /* inet_connection_sock has to be the first member of tcp_sock */
 334         struct inet_connection_sock     inet_conn;
 335         u16     tcp_header_len; /* Bytes of tcp header to send          */
 336         u16     xmit_size_goal_segs; /* Goal for segmenting output packets */
 337
 338 /*
 339  *      Header prediction flags
 340  *      0x5?10 << 16 + snd_wnd in net byte order
 341  */
 342         __be32  pred_flags;
 343
 344 /*
 345  *      RFC793 variables by their proper names. This means you can
 346  *      read the code and the spec side by side (and laugh ...)
 347  *      See RFC793 and RFC1122. The RFC writes these in capitals.
 348  */
 349         u32     rcv_nxt;        /* What we want to receive next         */
 350         u32     copied_seq;     /* Head of yet unread data              */
 351         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 352         u32     snd_nxt;        /* Next sequence we send                */
 353
 354         u32     snd_una;        /* First byte we want an ack for        */
 355         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 356         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 357         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 358
 359         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
 360         unsigned long   tsq_flags;
 361
 362         /* Data for direct copy to user */
 363         struct {
 364                 struct sk_buff_head     prequeue;
 365                 struct task_struct      *task;
 366                 struct iovec            *iov;
 367                 int                     memory;
 368                 int                     len;
 369 #ifdef CONFIG_NET_DMA
 370                 /* members for async copy */
 371                 struct dma_chan         *dma_chan;
 372                 int                     wakeup;
 373                 struct dma_pinned_list  *pinned_list;
 374                 dma_cookie_t            dma_cookie;
 375 #endif
 376         } ucopy;
 377
 378         u32     snd_wl1;        /* Sequence for window update           */
 379         u32     snd_wnd;        /* The window we expect to receive      */
 380         u32     max_window;     /* Maximal window ever seen from peer   */
 381         u32     mss_cache;      /* Cached effective mss, not including SACKS */
 382
 383         u32     window_clamp;   /* Maximal window to advertise          */
 384         u32     rcv_ssthresh;   /* Current window clamp                 */
 385
 386         u32     frto_highmark;  /* snd_nxt when RTO occurred */
 387         u16     advmss;         /* Advertised MSS                       */
 388         u8      frto_counter;   /* Number of new acks after RTO */
 389         u8      nonagle     : 4,/* Disable Nagle algorithm?             */
 390                 thin_lto    : 1,/* Use linear timeouts for thin streams */
 391                 thin_dupack : 1,/* Fast retransmit on first dupack      */
 392                 repair      : 1,
 393                 unused      : 1;
 394         u8      repair_queue;
 395         u8      do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
 396                 early_retrans_delayed:1, /* Delayed ER timer installed */
 397                 syn_data:1,     /* SYN includes data */
 398                 syn_fastopen:1; /* SYN includes Fast Open option */
 399
 400 /* RTT measurement */
 401         u32     srtt;           /* smoothed round trip time << 3        */
 402         u32     mdev;           /* medium deviation                     */
 403         u32     mdev_max;       /* maximal mdev for the last rtt period */
 404         u32     rttvar;         /* smoothed mdev_max                    */
 405         u32     rtt_seq;        /* sequence number to update rttvar     */
 406
 407         u32     packets_out;    /* Packets which are "in flight"        */
 408         u32     retrans_out;    /* Retransmitted packets out            */
 409
 410         u16     urg_data;       /* Saved octet of OOB data and control flags */
 411         u8      ecn_flags;      /* ECN status bits.                     */
 412         u8      reordering;     /* Packet reordering metric.            */
 413         u32     snd_up;         /* Urgent pointer               */
 414
 415         u8      keepalive_probes; /* num of allowed keep alive probes   */
 416 /*
 417  *      Options received (usually on last packet, some only on SYN packets).
 418  */
 419         struct tcp_options_received rx_opt;
 420
 421 /*
 422  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 423  */
 424         u32     snd_ssthresh;   /* Slow start size threshold            */
 425         u32     snd_cwnd;       /* Sending congestion window            */
 426         u32     snd_cwnd_cnt;   /* Linear increase counter              */
 427         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 428         u32     snd_cwnd_used;
 429         u32     snd_cwnd_stamp;
 430         u32     prior_cwnd;     /* Congestion window at start of Recovery. */
 431         u32     prr_delivered;  /* Number of newly delivered packets to
 432                                  * receiver in Recovery. */
 433         u32     prr_out;        /* Total number of pkts sent during Recovery. */
 434
 435         u32     rcv_wnd;        /* Current receiver window              */
 436         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 437         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 438         u32     lost_out;       /* Lost packets                 */
 439         u32     sacked_out;     /* SACK'd packets                       */
 440         u32     fackets_out;    /* FACK'd packets                       */
 441         u32     tso_deferred;
 442         u32     bytes_acked;    /* Appropriate Byte Counting - RFC3465 */
 443
 444         /* from STCP, retrans queue hinting */
 445         struct sk_buff* lost_skb_hint;
 446         struct sk_buff *scoreboard_skb_hint;
 447         struct sk_buff *retransmit_skb_hint;
 448
 449         struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
 450
 451         /* SACKs data, these 2 need to be together (see tcp_options_write) */
 452         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 453         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 454
 455         struct tcp_sack_block recv_sack_cache[4];
 456
 457         struct sk_buff *highest_sack;   /* skb just after the highest
 458                                          * skb with SACKed bit set
 459                                          * (validity guaranteed only if
 460                                          * sacked_out > 0)
 461                                          */
 462
 463         int     lost_cnt_hint;
 464         u32     retransmit_high;        /* L-bits may be on up to this seqno */
 465
 466         u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
 467
 468         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 469         u32     high_seq;       /* snd_nxt at onset of congestion       */
 470
 471         u32     retrans_stamp;  /* Timestamp of the last retransmit,
 472                                  * also used in SYN-SENT to remember stamp of
 473                                  * the first SYN. */
 474         u32     undo_marker;    /* tracking retrans started here. */
 475         int     undo_retrans;   /* number of undoable retransmissions. */
 476         u32     total_retrans;  /* Total retransmits for entire connection */
 477
 478         u32     urg_seq;        /* Seq of received urgent pointer */
 479         unsigned int            keepalive_time;   /* time before keep alive takes place */
 480         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 481
 482         int                     linger2;
 483
 484 /* Receiver side RTT estimation */
 485         struct {
 486                 u32     rtt;
 487                 u32     seq;
 488                 u32     time;
 489         } rcv_rtt_est;
 490
 491 /* Receiver queue space */
 492         struct {
 493                 int     space;
 494                 u32     seq;
 495                 u32     time;
 496         } rcvq_space;
 497
 498 /* TCP-specific MTU probe information. */
 499         struct {
 500                 u32               probe_seq_start;
 501                 u32               probe_seq_end;
 502         } mtu_probe;
 503         u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
 504                            * while socket was owned by user.
 505                            */
 506
 507 #ifdef CONFIG_TCP_MD5SIG
 508 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
 509         const struct tcp_sock_af_ops    *af_specific;
 510
 511 /* TCP MD5 Signature Option information */
 512         struct tcp_md5sig_info  __rcu *md5sig_info;
 513 #endif
 514
 515         /* When the cookie options are generated and exchanged, then this
 516          * object holds a reference to them (cookie_values->kref).  Also
 517          * contains related tcp_cookie_transactions fields.
 518          */
 519         struct tcp_cookie_values  *cookie_values;
 520
 521 /* TCP fastopen related information */
 522         struct tcp_fastopen_request *fastopen_req;
 523         /* fastopen_rsk points to request_sock that resulted in this big
 524          * socket. Used to retransmit SYNACKs etc.
 525          */
 526         struct request_sock *fastopen_rsk;
 527 };
 528
 529 enum tsq_flags {
 530         TSQ_THROTTLED,
 531         TSQ_QUEUED,
 532         TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
 533         TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
 534         TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
 535         TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
 536                                     * tcp_v{4|6}_mtu_reduced()
 537                                     */
 538 };
 539
 540 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 541 {
 542         return (struct tcp_sock *)sk;
 543 }
 544
 545 struct tcp_timewait_sock {
 546         struct inet_timewait_sock tw_sk;
 547         u32                       tw_rcv_nxt;
 548         u32                       tw_snd_nxt;
 549         u32                       tw_rcv_wnd;
 550         u32                       tw_ts_recent;
 551         long                      tw_ts_recent_stamp;
 552 #ifdef CONFIG_TCP_MD5SIG
 553         struct tcp_md5sig_key     *tw_md5_key;
 554 #endif
 555         /* Few sockets in timewait have cookies; in that case, then this
 556          * object holds a reference to them (tw_cookie_values->kref).
 557          */
 558         struct tcp_cookie_values  *tw_cookie_values;
 559 };
 560
 561 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 562 {
 563         return (struct tcp_timewait_sock *)sk;
 564 }
 565
 566 static inline bool tcp_passive_fastopen(const struct sock *sk)
 567 {
 568         return (sk->sk_state == TCP_SYN_RECV &&
 569                 tcp_sk(sk)->fastopen_rsk != NULL);
 570 }
 571
 572 static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc)
 573 {
 574         return foc->len != -1;
 575 }
 576
 577 extern void tcp_sock_destruct(struct sock *sk);
 578
 579 static inline int fastopen_init_queue(struct sock *sk, int backlog)
 580 {
 581         struct request_sock_queue *queue =
 582             &inet_csk(sk)->icsk_accept_queue;
 583
 584         if (queue->fastopenq == NULL) {
 585                 queue->fastopenq = kzalloc(
 586                     sizeof(struct fastopen_queue),
 587                     sk->sk_allocation);
 588                 if (queue->fastopenq == NULL)
 589                         return -ENOMEM;
 590
 591                 sk->sk_destruct = tcp_sock_destruct;
 592                 spin_lock_init(&queue->fastopenq->lock);
 593         }
 594         queue->fastopenq->max_qlen = backlog;
 595         return 0;
 596 }
 597
 598 #endif  /* __KERNEL__ */
 599
 600 #endif  /* _LINUX_TCP_H */