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_htonl(0x00800000),
  73         TCP_FLAG_ECE = __constant_htonl(0x00400000),
  74         TCP_FLAG_URG = __constant_htonl(0x00200000),
  75         TCP_FLAG_ACK = __constant_htonl(0x00100000),
  76         TCP_FLAG_PSH = __constant_htonl(0x00080000),
  77         TCP_FLAG_RST = __constant_htonl(0x00040000),
  78         TCP_FLAG_SYN = __constant_htonl(0x00020000),
  79         TCP_FLAG_FIN = __constant_htonl(0x00010000),
  80         TCP_RESERVED_BITS = __constant_htonl(0x0F000000),
  81         TCP_DATA_OFFSET = __constant_htonl(0xF0000000)
  82 };
  83
  84 /* TCP socket options */
  85 #define TCP_NODELAY             1       /* Turn off Nagle's algorithm. */
  86 #define TCP_MAXSEG              2       /* Limit MSS */
  87 #define TCP_CORK                3       /* Never send partially complete segments */
  88 #define TCP_KEEPIDLE            4       /* Start keeplives after this period */
  89 #define TCP_KEEPINTVL           5       /* Interval between keepalives */
  90 #define TCP_KEEPCNT             6       /* Number of keepalives before death */
  91 #define TCP_SYNCNT              7       /* Number of SYN retransmits */
  92 #define TCP_LINGER2             8       /* Life time of orphaned FIN-WAIT-2 state */
  93 #define TCP_DEFER_ACCEPT        9       /* Wake up listener only when data arrive */
  94 #define TCP_WINDOW_CLAMP        10      /* Bound advertised window */
  95 #define TCP_INFO                11      /* Information about this connection. */
  96 #define TCP_QUICKACK            12      /* Block/reenable quick acks */
  97 #define TCP_CONGESTION          13      /* Congestion control algorithm */
  98 #define TCP_MD5SIG              14      /* TCP MD5 Signature (RFC2385) */
  99
 100 #define TCPI_OPT_TIMESTAMPS     1
 101 #define TCPI_OPT_SACK           2
 102 #define TCPI_OPT_WSCALE         4
 103 #define TCPI_OPT_ECN            8
 104
 105 enum tcp_ca_state
 106 {
 107         TCP_CA_Open = 0,
 108 #define TCPF_CA_Open    (1<<TCP_CA_Open)
 109         TCP_CA_Disorder = 1,
 110 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
 111         TCP_CA_CWR = 2,
 112 #define TCPF_CA_CWR     (1<<TCP_CA_CWR)
 113         TCP_CA_Recovery = 3,
 114 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
 115         TCP_CA_Loss = 4
 116 #define TCPF_CA_Loss    (1<<TCP_CA_Loss)
 117 };
 118
 119 struct tcp_info
 120 {
 121         __u8    tcpi_state;
 122         __u8    tcpi_ca_state;
 123         __u8    tcpi_retransmits;
 124         __u8    tcpi_probes;
 125         __u8    tcpi_backoff;
 126         __u8    tcpi_options;
 127         __u8    tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
 128
 129         __u32   tcpi_rto;
 130         __u32   tcpi_ato;
 131         __u32   tcpi_snd_mss;
 132         __u32   tcpi_rcv_mss;
 133
 134         __u32   tcpi_unacked;
 135         __u32   tcpi_sacked;
 136         __u32   tcpi_lost;
 137         __u32   tcpi_retrans;
 138         __u32   tcpi_fackets;
 139
 140         /* Times. */
 141         __u32   tcpi_last_data_sent;
 142         __u32   tcpi_last_ack_sent;     /* Not remembered, sorry. */
 143         __u32   tcpi_last_data_recv;
 144         __u32   tcpi_last_ack_recv;
 145
 146         /* Metrics. */
 147         __u32   tcpi_pmtu;
 148         __u32   tcpi_rcv_ssthresh;
 149         __u32   tcpi_rtt;
 150         __u32   tcpi_rttvar;
 151         __u32   tcpi_snd_ssthresh;
 152         __u32   tcpi_snd_cwnd;
 153         __u32   tcpi_advmss;
 154         __u32   tcpi_reordering;
 155
 156         __u32   tcpi_rcv_rtt;
 157         __u32   tcpi_rcv_space;
 158
 159         __u32   tcpi_total_retrans;
 160 };
 161
 162 /* for TCP_MD5SIG socket option */
 163 #define TCP_MD5SIG_MAXKEYLEN    80
 164
 165 struct tcp_md5sig {
 166         struct __kernel_sockaddr_storage tcpm_addr;     /* address associated */
 167         __u16   __tcpm_pad1;                            /* zero */
 168         __u16   tcpm_keylen;                            /* key length */
 169         __u32   __tcpm_pad2;                            /* zero */
 170         __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
 171 };
 172
 173 #ifdef __KERNEL__
 174
 175 #include <linux/skbuff.h>
 176 #include <linux/dmaengine.h>
 177 #include <net/sock.h>
 178 #include <net/inet_connection_sock.h>
 179 #include <net/inet_timewait_sock.h>
 180
 181 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
 182 {
 183         return (struct tcphdr *)skb_transport_header(skb);
 184 }
 185
 186 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
 187 {
 188         return tcp_hdr(skb)->doff * 4;
 189 }
 190
 191 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 192 {
 193         return (tcp_hdr(skb)->doff - 5) * 4;
 194 }
 195
 196 /* This defines a selective acknowledgement block. */
 197 struct tcp_sack_block_wire {
 198         __be32  start_seq;
 199         __be32  end_seq;
 200 };
 201
 202 struct tcp_sack_block {
 203         u32     start_seq;
 204         u32     end_seq;
 205 };
 206
 207 struct tcp_options_received {
 208 /*      PAWS/RTTM data  */
 209         long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 210         u32     ts_recent;      /* Time stamp to echo next              */
 211         u32     rcv_tsval;      /* Time stamp value                     */
 212         u32     rcv_tsecr;      /* Time stamp echo reply                */
 213         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 214                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 215                 dsack : 1,      /* D-SACK is scheduled                  */
 216                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 217                 sack_ok : 4,    /* SACK seen on SYN packet              */
 218                 snd_wscale : 4, /* Window scaling received from sender  */
 219                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 220 /*      SACKs data      */
 221         u8      eff_sacks;      /* Size of SACK array to send with next packet */
 222         u8      num_sacks;      /* Number of SACK blocks                */
 223         u16     user_mss;       /* mss requested by user in ioctl */
 224         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 225 };
 226
 227 /* This is the max number of SACKS that we'll generate and process. It's safe
 228  * to increse this, although since:
 229  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 230  * only four options will fit in a standard TCP header */
 231 #define TCP_NUM_SACKS 4
 232
 233 struct tcp_request_sock {
 234         struct inet_request_sock        req;
 235 #ifdef CONFIG_TCP_MD5SIG
 236         /* Only used by TCP MD5 Signature so far. */
 237         struct tcp_request_sock_ops     *af_specific;
 238 #endif
 239         u32                             rcv_isn;
 240         u32                             snt_isn;
 241 };
 242
 243 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 244 {
 245         return (struct tcp_request_sock *)req;
 246 }
 247
 248 struct tcp_sock {
 249         /* inet_connection_sock has to be the first member of tcp_sock */
 250         struct inet_connection_sock     inet_conn;
 251         u16     tcp_header_len; /* Bytes of tcp header to send          */
 252         u16     xmit_size_goal; /* Goal for segmenting output packets   */
 253
 254 /*
 255  *      Header prediction flags
 256  *      0x5?10 << 16 + snd_wnd in net byte order
 257  */
 258         __be32  pred_flags;
 259
 260 /*
 261  *      RFC793 variables by their proper names. This means you can
 262  *      read the code and the spec side by side (and laugh ...)
 263  *      See RFC793 and RFC1122. The RFC writes these in capitals.
 264  */
 265         u32     rcv_nxt;        /* What we want to receive next         */
 266         u32     copied_seq;     /* Head of yet unread data              */
 267         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 268         u32     snd_nxt;        /* Next sequence we send                */
 269
 270         u32     snd_una;        /* First byte we want an ack for        */
 271         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 272         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 273         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 274
 275         /* Data for direct copy to user */
 276         struct {
 277                 struct sk_buff_head     prequeue;
 278                 struct task_struct      *task;
 279                 struct iovec            *iov;
 280                 int                     memory;
 281                 int                     len;
 282 #ifdef CONFIG_NET_DMA
 283                 /* members for async copy */
 284                 struct dma_chan         *dma_chan;
 285                 int                     wakeup;
 286                 struct dma_pinned_list  *pinned_list;
 287                 dma_cookie_t            dma_cookie;
 288 #endif
 289         } ucopy;
 290
 291         u32     snd_wl1;        /* Sequence for window update           */
 292         u32     snd_wnd;        /* The window we expect to receive      */
 293         u32     max_window;     /* Maximal window ever seen from peer   */
 294         u32     mss_cache;      /* Cached effective mss, not including SACKS */
 295
 296         u32     window_clamp;   /* Maximal window to advertise          */
 297         u32     rcv_ssthresh;   /* Current window clamp                 */
 298
 299         u32     frto_highmark;  /* snd_nxt when RTO occurred */
 300         u16     advmss;         /* Advertised MSS                       */
 301         u8      frto_counter;   /* Number of new acks after RTO */
 302         u8      nonagle;        /* Disable Nagle algorithm?             */
 303
 304 /* RTT measurement */
 305         u32     srtt;           /* smoothed round trip time << 3        */
 306         u32     mdev;           /* medium deviation                     */
 307         u32     mdev_max;       /* maximal mdev for the last rtt period */
 308         u32     rttvar;         /* smoothed mdev_max                    */
 309         u32     rtt_seq;        /* sequence number to update rttvar     */
 310
 311         u32     packets_out;    /* Packets which are "in flight"        */
 312         u32     retrans_out;    /* Retransmitted packets out            */
 313
 314         u16     urg_data;       /* Saved octet of OOB data and control flags */
 315         u8      ecn_flags;      /* ECN status bits.                     */
 316         u8      reordering;     /* Packet reordering metric.            */
 317         u32     snd_up;         /* Urgent pointer               */
 318
 319         u8      keepalive_probes; /* num of allowed keep alive probes   */
 320 /*
 321  *      Options received (usually on last packet, some only on SYN packets).
 322  */
 323         struct tcp_options_received rx_opt;
 324
 325 /*
 326  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 327  */
 328         u32     snd_ssthresh;   /* Slow start size threshold            */
 329         u32     snd_cwnd;       /* Sending congestion window            */
 330         u32     snd_cwnd_cnt;   /* Linear increase counter              */
 331         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 332         u32     snd_cwnd_used;
 333         u32     snd_cwnd_stamp;
 334
 335         u32     rcv_wnd;        /* Current receiver window              */
 336         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 337         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 338         u32     lost_out;       /* Lost packets                 */
 339         u32     sacked_out;     /* SACK'd packets                       */
 340         u32     fackets_out;    /* FACK'd packets                       */
 341         u32     tso_deferred;
 342         u32     bytes_acked;    /* Appropriate Byte Counting - RFC3465 */
 343
 344         /* from STCP, retrans queue hinting */
 345         struct sk_buff* lost_skb_hint;
 346         struct sk_buff *scoreboard_skb_hint;
 347         struct sk_buff *retransmit_skb_hint;
 348
 349         struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
 350
 351         /* SACKs data, these 2 need to be together (see tcp_build_and_update_options) */
 352         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 353         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 354
 355         struct tcp_sack_block recv_sack_cache[4];
 356
 357         struct sk_buff *highest_sack;   /* highest skb with SACK received
 358                                          * (validity guaranteed only if
 359                                          * sacked_out > 0)
 360                                          */
 361
 362         int     lost_cnt_hint;
 363         u32     retransmit_high;        /* L-bits may be on up to this seqno */
 364
 365         u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
 366
 367         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 368         u32     high_seq;       /* snd_nxt at onset of congestion       */
 369
 370         u32     retrans_stamp;  /* Timestamp of the last retransmit,
 371                                  * also used in SYN-SENT to remember stamp of
 372                                  * the first SYN. */
 373         u32     undo_marker;    /* tracking retrans started here. */
 374         int     undo_retrans;   /* number of undoable retransmissions. */
 375         u32     total_retrans;  /* Total retransmits for entire connection */
 376
 377         u32     urg_seq;        /* Seq of received urgent pointer */
 378         unsigned int            keepalive_time;   /* time before keep alive takes place */
 379         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 380
 381         unsigned long last_synq_overflow;
 382
 383 /* Receiver side RTT estimation */
 384         struct {
 385                 u32     rtt;
 386                 u32     seq;
 387                 u32     time;
 388         } rcv_rtt_est;
 389
 390 /* Receiver queue space */
 391         struct {
 392                 int     space;
 393                 u32     seq;
 394                 u32     time;
 395         } rcvq_space;
 396
 397 /* TCP-specific MTU probe information. */
 398         struct {
 399                 u32               probe_seq_start;
 400                 u32               probe_seq_end;
 401         } mtu_probe;
 402
 403 #ifdef CONFIG_TCP_MD5SIG
 404 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
 405         struct tcp_sock_af_ops  *af_specific;
 406
 407 /* TCP MD5 Signagure Option information */
 408         struct tcp_md5sig_info  *md5sig_info;
 409 #endif
 410
 411         int                     linger2;
 412 };
 413
 414 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 415 {
 416         return (struct tcp_sock *)sk;
 417 }
 418
 419 struct tcp_timewait_sock {
 420         struct inet_timewait_sock tw_sk;
 421         u32                       tw_rcv_nxt;
 422         u32                       tw_snd_nxt;
 423         u32                       tw_rcv_wnd;
 424         u32                       tw_ts_recent;
 425         long                      tw_ts_recent_stamp;
 426 #ifdef CONFIG_TCP_MD5SIG
 427         u16                       tw_md5_keylen;
 428         u8                        tw_md5_key[TCP_MD5SIG_MAXKEYLEN];
 429 #endif
 430 };
 431
 432 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 433 {
 434         return (struct tcp_timewait_sock *)sk;
 435 }
 436
 437 #endif
 438
 439 #endif  /* _LINUX_TCP_H */