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 = __cpu_to_be32(0x00800000),
  73         TCP_FLAG_ECE = __cpu_to_be32(0x00400000),
  74         TCP_FLAG_URG = __cpu_to_be32(0x00200000),
  75         TCP_FLAG_ACK = __cpu_to_be32(0x00100000),
  76         TCP_FLAG_PSH = __cpu_to_be32(0x00080000),
  77         TCP_FLAG_RST = __cpu_to_be32(0x00040000),
  78         TCP_FLAG_SYN = __cpu_to_be32(0x00020000),
  79         TCP_FLAG_FIN = __cpu_to_be32(0x00010000),
  80         TCP_RESERVED_BITS = __cpu_to_be32(0x0F000000),
  81         TCP_DATA_OFFSET = __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
 106 #define TCPI_OPT_TIMESTAMPS     1
 107 #define TCPI_OPT_SACK           2
 108 #define TCPI_OPT_WSCALE         4
 109 #define TCPI_OPT_ECN            8
 110
 111 enum tcp_ca_state {
 112         TCP_CA_Open = 0,
 113 #define TCPF_CA_Open    (1<<TCP_CA_Open)
 114         TCP_CA_Disorder = 1,
 115 #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
 116         TCP_CA_CWR = 2,
 117 #define TCPF_CA_CWR     (1<<TCP_CA_CWR)
 118         TCP_CA_Recovery = 3,
 119 #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
 120         TCP_CA_Loss = 4
 121 #define TCPF_CA_Loss    (1<<TCP_CA_Loss)
 122 };
 123
 124 struct tcp_info {
 125         __u8    tcpi_state;
 126         __u8    tcpi_ca_state;
 127         __u8    tcpi_retransmits;
 128         __u8    tcpi_probes;
 129         __u8    tcpi_backoff;
 130         __u8    tcpi_options;
 131         __u8    tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
 132
 133         __u32   tcpi_rto;
 134         __u32   tcpi_ato;
 135         __u32   tcpi_snd_mss;
 136         __u32   tcpi_rcv_mss;
 137
 138         __u32   tcpi_unacked;
 139         __u32   tcpi_sacked;
 140         __u32   tcpi_lost;
 141         __u32   tcpi_retrans;
 142         __u32   tcpi_fackets;
 143
 144         /* Times. */
 145         __u32   tcpi_last_data_sent;
 146         __u32   tcpi_last_ack_sent;     /* Not remembered, sorry. */
 147         __u32   tcpi_last_data_recv;
 148         __u32   tcpi_last_ack_recv;
 149
 150         /* Metrics. */
 151         __u32   tcpi_pmtu;
 152         __u32   tcpi_rcv_ssthresh;
 153         __u32   tcpi_rtt;
 154         __u32   tcpi_rttvar;
 155         __u32   tcpi_snd_ssthresh;
 156         __u32   tcpi_snd_cwnd;
 157         __u32   tcpi_advmss;
 158         __u32   tcpi_reordering;
 159
 160         __u32   tcpi_rcv_rtt;
 161         __u32   tcpi_rcv_space;
 162
 163         __u32   tcpi_total_retrans;
 164 };
 165
 166 /* for TCP_MD5SIG socket option */
 167 #define TCP_MD5SIG_MAXKEYLEN    80
 168
 169 struct tcp_md5sig {
 170         struct __kernel_sockaddr_storage tcpm_addr;     /* address associated */
 171         __u16   __tcpm_pad1;                            /* zero */
 172         __u16   tcpm_keylen;                            /* key length */
 173         __u32   __tcpm_pad2;                            /* zero */
 174         __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
 175 };
 176
 177 #ifdef __KERNEL__
 178
 179 #include <linux/skbuff.h>
 180 #include <linux/dmaengine.h>
 181 #include <net/sock.h>
 182 #include <net/inet_connection_sock.h>
 183 #include <net/inet_timewait_sock.h>
 184
 185 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
 186 {
 187         return (struct tcphdr *)skb_transport_header(skb);
 188 }
 189
 190 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
 191 {
 192         return tcp_hdr(skb)->doff * 4;
 193 }
 194
 195 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 196 {
 197         return (tcp_hdr(skb)->doff - 5) * 4;
 198 }
 199
 200 /* This defines a selective acknowledgement block. */
 201 struct tcp_sack_block_wire {
 202         __be32  start_seq;
 203         __be32  end_seq;
 204 };
 205
 206 struct tcp_sack_block {
 207         u32     start_seq;
 208         u32     end_seq;
 209 };
 210
 211 struct tcp_options_received {
 212 /*      PAWS/RTTM data  */
 213         long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 214         u32     ts_recent;      /* Time stamp to echo next              */
 215         u32     rcv_tsval;      /* Time stamp value                     */
 216         u32     rcv_tsecr;      /* Time stamp echo reply                */
 217         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 218                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 219                 dsack : 1,      /* D-SACK is scheduled                  */
 220                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 221                 sack_ok : 4,    /* SACK seen on SYN packet              */
 222                 snd_wscale : 4, /* Window scaling received from sender  */
 223                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 224 /*      SACKs data      */
 225         u8      num_sacks;      /* Number of SACK blocks                */
 226         u16     user_mss;       /* mss requested by user in ioctl */
 227         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 228 };
 229
 230 /* This is the max number of SACKS that we'll generate and process. It's safe
 231  * to increse this, although since:
 232  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
 233  * only four options will fit in a standard TCP header */
 234 #define TCP_NUM_SACKS 4
 235
 236 struct tcp_request_sock {
 237         struct inet_request_sock        req;
 238 #ifdef CONFIG_TCP_MD5SIG
 239         /* Only used by TCP MD5 Signature so far. */
 240         const struct tcp_request_sock_ops *af_specific;
 241 #endif
 242         u32                             rcv_isn;
 243         u32                             snt_isn;
 244 };
 245
 246 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
 247 {
 248         return (struct tcp_request_sock *)req;
 249 }
 250
 251 struct tcp_sock {
 252         /* inet_connection_sock has to be the first member of tcp_sock */
 253         struct inet_connection_sock     inet_conn;
 254         u16     tcp_header_len; /* Bytes of tcp header to send          */
 255         u16     xmit_size_goal_segs; /* Goal for segmenting output packets */
 256
 257 /*
 258  *      Header prediction flags
 259  *      0x5?10 << 16 + snd_wnd in net byte order
 260  */
 261         __be32  pred_flags;
 262
 263 /*
 264  *      RFC793 variables by their proper names. This means you can
 265  *      read the code and the spec side by side (and laugh ...)
 266  *      See RFC793 and RFC1122. The RFC writes these in capitals.
 267  */
 268         u32     rcv_nxt;        /* What we want to receive next         */
 269         u32     copied_seq;     /* Head of yet unread data              */
 270         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
 271         u32     snd_nxt;        /* Next sequence we send                */
 272
 273         u32     snd_una;        /* First byte we want an ack for        */
 274         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
 275         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
 276         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
 277
 278         /* Data for direct copy to user */
 279         struct {
 280                 struct sk_buff_head     prequeue;
 281                 struct task_struct      *task;
 282                 struct iovec            *iov;
 283                 int                     memory;
 284                 int                     len;
 285 #ifdef CONFIG_NET_DMA
 286                 /* members for async copy */
 287                 struct dma_chan         *dma_chan;
 288                 int                     wakeup;
 289                 struct dma_pinned_list  *pinned_list;
 290                 dma_cookie_t            dma_cookie;
 291 #endif
 292         } ucopy;
 293
 294         u32     snd_wl1;        /* Sequence for window update           */
 295         u32     snd_wnd;        /* The window we expect to receive      */
 296         u32     max_window;     /* Maximal window ever seen from peer   */
 297         u32     mss_cache;      /* Cached effective mss, not including SACKS */
 298
 299         u32     window_clamp;   /* Maximal window to advertise          */
 300         u32     rcv_ssthresh;   /* Current window clamp                 */
 301
 302         u32     frto_highmark;  /* snd_nxt when RTO occurred */
 303         u16     advmss;         /* Advertised MSS                       */
 304         u8      frto_counter;   /* Number of new acks after RTO */
 305         u8      nonagle;        /* Disable Nagle algorithm?             */
 306
 307 /* RTT measurement */
 308         u32     srtt;           /* smoothed round trip time << 3        */
 309         u32     mdev;           /* medium deviation                     */
 310         u32     mdev_max;       /* maximal mdev for the last rtt period */
 311         u32     rttvar;         /* smoothed mdev_max                    */
 312         u32     rtt_seq;        /* sequence number to update rttvar     */
 313
 314         u32     packets_out;    /* Packets which are "in flight"        */
 315         u32     retrans_out;    /* Retransmitted packets out            */
 316
 317         u16     urg_data;       /* Saved octet of OOB data and control flags */
 318         u8      ecn_flags;      /* ECN status bits.                     */
 319         u8      reordering;     /* Packet reordering metric.            */
 320         u32     snd_up;         /* Urgent pointer               */
 321
 322         u8      keepalive_probes; /* num of allowed keep alive probes   */
 323 /*
 324  *      Options received (usually on last packet, some only on SYN packets).
 325  */
 326         struct tcp_options_received rx_opt;
 327
 328 /*
 329  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
 330  */
 331         u32     snd_ssthresh;   /* Slow start size threshold            */
 332         u32     snd_cwnd;       /* Sending congestion window            */
 333         u32     snd_cwnd_cnt;   /* Linear increase counter              */
 334         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
 335         u32     snd_cwnd_used;
 336         u32     snd_cwnd_stamp;
 337
 338         u32     rcv_wnd;        /* Current receiver window              */
 339         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
 340         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
 341         u32     lost_out;       /* Lost packets                 */
 342         u32     sacked_out;     /* SACK'd packets                       */
 343         u32     fackets_out;    /* FACK'd packets                       */
 344         u32     tso_deferred;
 345         u32     bytes_acked;    /* Appropriate Byte Counting - RFC3465 */
 346
 347         /* from STCP, retrans queue hinting */
 348         struct sk_buff* lost_skb_hint;
 349         struct sk_buff *scoreboard_skb_hint;
 350         struct sk_buff *retransmit_skb_hint;
 351
 352         struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
 353
 354         /* SACKs data, these 2 need to be together (see tcp_build_and_update_options) */
 355         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
 356         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
 357
 358         struct tcp_sack_block recv_sack_cache[4];
 359
 360         struct sk_buff *highest_sack;   /* highest skb with SACK received
 361                                          * (validity guaranteed only if
 362                                          * sacked_out > 0)
 363                                          */
 364
 365         int     lost_cnt_hint;
 366         u32     retransmit_high;        /* L-bits may be on up to this seqno */
 367
 368         u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
 369
 370         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
 371         u32     high_seq;       /* snd_nxt at onset of congestion       */
 372
 373         u32     retrans_stamp;  /* Timestamp of the last retransmit,
 374                                  * also used in SYN-SENT to remember stamp of
 375                                  * the first SYN. */
 376         u32     undo_marker;    /* tracking retrans started here. */
 377         int     undo_retrans;   /* number of undoable retransmissions. */
 378         u32     total_retrans;  /* Total retransmits for entire connection */
 379
 380         u32     urg_seq;        /* Seq of received urgent pointer */
 381         unsigned int            keepalive_time;   /* time before keep alive takes place */
 382         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
 383
 384         int                     linger2;
 385
 386 /* Receiver side RTT estimation */
 387         struct {
 388                 u32     rtt;
 389                 u32     seq;
 390                 u32     time;
 391         } rcv_rtt_est;
 392
 393 /* Receiver queue space */
 394         struct {
 395                 int     space;
 396                 u32     seq;
 397                 u32     time;
 398         } rcvq_space;
 399
 400 /* TCP-specific MTU probe information. */
 401         struct {
 402                 u32               probe_seq_start;
 403                 u32               probe_seq_end;
 404         } mtu_probe;
 405
 406 #ifdef CONFIG_TCP_MD5SIG
 407 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
 408         const struct tcp_sock_af_ops    *af_specific;
 409
 410 /* TCP MD5 Signature Option information */
 411         struct tcp_md5sig_info  *md5sig_info;
 412 #endif
 413 };
 414
 415 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
 416 {
 417         return (struct tcp_sock *)sk;
 418 }
 419
 420 struct tcp_timewait_sock {
 421         struct inet_timewait_sock tw_sk;
 422         u32                       tw_rcv_nxt;
 423         u32                       tw_snd_nxt;
 424         u32                       tw_rcv_wnd;
 425         u32                       tw_ts_recent;
 426         long                      tw_ts_recent_stamp;
 427 #ifdef CONFIG_TCP_MD5SIG
 428         u16                       tw_md5_keylen;
 429         u8                        tw_md5_key[TCP_MD5SIG_MAXKEYLEN];
 430 #endif
 431 };
 432
 433 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 434 {
 435         return (struct tcp_timewait_sock *)sk;
 436 }
 437
 438 #endif
 439
 440 #endif  /* _LINUX_TCP_H */