LCOV - code coverage report
Current view: top level - include/linux - tcp.h (source / functions) Hit Total Coverage
Test: coverage.info Lines: 5 5 100.0 %
Date: 2017-01-25 Functions: 1 1 100.0 %

          Line data    Source code
       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             : #define TCP_COOKIE_TRANSACTIONS 15      /* TCP Cookie Transactions */
     106             : 
     107             : /* for TCP_INFO socket option */
     108             : #define TCPI_OPT_TIMESTAMPS     1
     109             : #define TCPI_OPT_SACK           2
     110             : #define TCPI_OPT_WSCALE         4
     111             : #define TCPI_OPT_ECN            8
     112             : 
     113             : enum tcp_ca_state {
     114             :         TCP_CA_Open = 0,
     115             : #define TCPF_CA_Open    (1<<TCP_CA_Open)
     116             :         TCP_CA_Disorder = 1,
     117             : #define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
     118             :         TCP_CA_CWR = 2,
     119             : #define TCPF_CA_CWR     (1<<TCP_CA_CWR)
     120             :         TCP_CA_Recovery = 3,
     121             : #define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
     122             :         TCP_CA_Loss = 4
     123             : #define TCPF_CA_Loss    (1<<TCP_CA_Loss)
     124             : };
     125             : 
     126             : struct tcp_info {
     127             :         __u8    tcpi_state;
     128             :         __u8    tcpi_ca_state;
     129             :         __u8    tcpi_retransmits;
     130             :         __u8    tcpi_probes;
     131             :         __u8    tcpi_backoff;
     132             :         __u8    tcpi_options;
     133             :         __u8    tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
     134             : 
     135             :         __u32   tcpi_rto;
     136             :         __u32   tcpi_ato;
     137             :         __u32   tcpi_snd_mss;
     138             :         __u32   tcpi_rcv_mss;
     139             : 
     140             :         __u32   tcpi_unacked;
     141             :         __u32   tcpi_sacked;
     142             :         __u32   tcpi_lost;
     143             :         __u32   tcpi_retrans;
     144             :         __u32   tcpi_fackets;
     145             : 
     146             :         /* Times. */
     147             :         __u32   tcpi_last_data_sent;
     148             :         __u32   tcpi_last_ack_sent;     /* Not remembered, sorry. */
     149             :         __u32   tcpi_last_data_recv;
     150             :         __u32   tcpi_last_ack_recv;
     151             : 
     152             :         /* Metrics. */
     153             :         __u32   tcpi_pmtu;
     154             :         __u32   tcpi_rcv_ssthresh;
     155             :         __u32   tcpi_rtt;
     156             :         __u32   tcpi_rttvar;
     157             :         __u32   tcpi_snd_ssthresh;
     158             :         __u32   tcpi_snd_cwnd;
     159             :         __u32   tcpi_advmss;
     160             :         __u32   tcpi_reordering;
     161             : 
     162             :         __u32   tcpi_rcv_rtt;
     163             :         __u32   tcpi_rcv_space;
     164             : 
     165             :         __u32   tcpi_total_retrans;
     166             : };
     167             : 
     168             : /* for TCP_MD5SIG socket option */
     169             : #define TCP_MD5SIG_MAXKEYLEN    80
     170             : 
     171             : struct tcp_md5sig {
     172             :         struct __kernel_sockaddr_storage tcpm_addr;     /* address associated */
     173             :         __u16   __tcpm_pad1;                            /* zero */
     174             :         __u16   tcpm_keylen;                            /* key length */
     175             :         __u32   __tcpm_pad2;                            /* zero */
     176             :         __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
     177             : };
     178             : 
     179             : /* for TCP_COOKIE_TRANSACTIONS (TCPCT) socket option */
     180             : #define TCP_COOKIE_MIN           8              /*  64-bits */
     181             : #define TCP_COOKIE_MAX          16              /* 128-bits */
     182             : #define TCP_COOKIE_PAIR_SIZE    (2*TCP_COOKIE_MAX)
     183             : 
     184             : /* Flags for both getsockopt and setsockopt */
     185             : #define TCP_COOKIE_IN_ALWAYS    (1 << 0)  /* Discard SYN without cookie */
     186             : #define TCP_COOKIE_OUT_NEVER    (1 << 1)  /* Prohibit outgoing cookies,
     187             :                                                  * supercedes everything. */
     188             : 
     189             : /* Flags for getsockopt */
     190             : #define TCP_S_DATA_IN           (1 << 2)  /* Was data received? */
     191             : #define TCP_S_DATA_OUT          (1 << 3)  /* Was data sent? */
     192             : 
     193             : /* TCP_COOKIE_TRANSACTIONS data */
     194             : struct tcp_cookie_transactions {
     195             :         __u16   tcpct_flags;                    /* see above */
     196             :         __u8    __tcpct_pad1;                   /* zero */
     197             :         __u8    tcpct_cookie_desired;           /* bytes */
     198             :         __u16   tcpct_s_data_desired;           /* bytes of variable data */
     199             :         __u16   tcpct_used;                     /* bytes in value */
     200             :         __u8    tcpct_value[TCP_MSS_DEFAULT];
     201             : };
     202             : 
     203             : #ifdef __KERNEL__
     204             : 
     205             : #include <linux/skbuff.h>
     206             : #include <linux/dmaengine.h>
     207             : #include <net/sock.h>
     208             : #include <net/inet_connection_sock.h>
     209             : #include <net/inet_timewait_sock.h>
     210             : 
     211             : static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
     212             : {
     213             :         return (struct tcphdr *)skb_transport_header(skb);
     214             : }
     215             : 
     216             : static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
     217             : {
     218             :         return tcp_hdr(skb)->doff * 4;
     219             : }
     220             : 
     221             : static inline unsigned int tcp_optlen(const struct sk_buff *skb)
     222             : {
     223             :         return (tcp_hdr(skb)->doff - 5) * 4;
     224             : }
     225             : 
     226             : /* This defines a selective acknowledgement block. */
     227             : struct tcp_sack_block_wire {
     228             :         __be32  start_seq;
     229             :         __be32  end_seq;
     230             : };
     231           1 : 
     232             : struct tcp_sack_block {
     233             :         u32     start_seq;
     234             :         u32     end_seq;
     235             : };
     236           1 : 
     237             : struct tcp_options_received {
     238             : /*      PAWS/RTTM data  */
     239             :         long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
     240             :         u32     ts_recent;      /* Time stamp to echo next              */
     241             :         u32     rcv_tsval;      /* Time stamp value                     */
     242             :         u32     rcv_tsecr;      /* Time stamp echo reply                */
     243             :         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
     244             :                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
     245             :                 dsack : 1,      /* D-SACK is scheduled                  */
     246             :                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
     247             :                 sack_ok : 4,    /* SACK seen on SYN packet              */
     248             :                 snd_wscale : 4, /* Window scaling received from sender  */
     249             :                 rcv_wscale : 4; /* Window scaling to send to receiver   */
     250             :         u8      cookie_plus:6,  /* bytes in authenticator/cookie option */
     251             :                 cookie_out_never:1,
     252             :                 cookie_in_always:1;
     253             :         u8      num_sacks;      /* Number of SACK blocks                */
     254             :         u16     user_mss;       /* mss requested by user in ioctl       */
     255             :         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
     256             : };
     257             : 
     258             : static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
     259             : {
     260             :         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
     261             :         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
     262             :         rx_opt->cookie_plus = 0;
     263             : }
     264           1 : 
     265             : /* This is the max number of SACKS that we'll generate and process. It's safe
     266             :  * to increase this, although since:
     267             :  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
     268             :  * only four options will fit in a standard TCP header */
     269             : #define TCP_NUM_SACKS 4
     270             : 
     271             : struct tcp_cookie_values;
     272             : struct tcp_request_sock_ops;
     273             : 
     274             : struct tcp_request_sock {
     275             :         struct inet_request_sock        req;
     276             : #ifdef CONFIG_TCP_MD5SIG
     277             :         /* Only used by TCP MD5 Signature so far. */
     278             :         const struct tcp_request_sock_ops *af_specific;
     279             : #endif
     280             :         u32                             rcv_isn;
     281             :         u32                             snt_isn;
     282             : };
     283             : 
     284             : static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
     285             : {
     286             :         return (struct tcp_request_sock *)req;
     287             : }
     288           5 : 
     289             : struct tcp_sock {
     290             :         /* inet_connection_sock has to be the first member of tcp_sock */
     291             :         struct inet_connection_sock     inet_conn;
     292             :         u16     tcp_header_len; /* Bytes of tcp header to send          */
     293             :         u16     xmit_size_goal_segs; /* Goal for segmenting output packets */
     294             : 
     295             : /*
     296             :  *      Header prediction flags
     297             :  *      0x5?10 << 16 + snd_wnd in net byte order
     298             :  */
     299             :         __be32  pred_flags;
     300             : 
     301             : /*
     302             :  *      RFC793 variables by their proper names. This means you can
     303             :  *      read the code and the spec side by side (and laugh ...)
     304             :  *      See RFC793 and RFC1122. The RFC writes these in capitals.
     305             :  */
     306             :         u32     rcv_nxt;        /* What we want to receive next         */
     307             :         u32     copied_seq;     /* Head of yet unread data              */
     308             :         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
     309             :         u32     snd_nxt;        /* Next sequence we send                */
     310             : 
     311             :         u32     snd_una;        /* First byte we want an ack for        */
     312             :         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
     313             :         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
     314             :         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
     315             : 
     316             :         /* Data for direct copy to user */
     317             :         struct {
     318             :                 struct sk_buff_head     prequeue;
     319             :                 struct task_struct      *task;
     320             :                 struct iovec            *iov;
     321             :                 int                     memory;
     322             :                 int                     len;
     323             : #ifdef CONFIG_NET_DMA
     324             :                 /* members for async copy */
     325             :                 struct dma_chan         *dma_chan;
     326             :                 int                     wakeup;
     327             :                 struct dma_pinned_list  *pinned_list;
     328             :                 dma_cookie_t            dma_cookie;
     329             : #endif
     330             :         } ucopy;
     331             : 
     332             :         u32     snd_wl1;        /* Sequence for window update           */
     333             :         u32     snd_wnd;        /* The window we expect to receive      */
     334             :         u32     max_window;     /* Maximal window ever seen from peer   */
     335             :         u32     mss_cache;      /* Cached effective mss, not including SACKS */
     336             : 
     337             :         u32     window_clamp;   /* Maximal window to advertise          */
     338             :         u32     rcv_ssthresh;   /* Current window clamp                 */
     339             : 
     340             :         u32     frto_highmark;  /* snd_nxt when RTO occurred */
     341             :         u16     advmss;         /* Advertised MSS                       */
     342             :         u8      frto_counter;   /* Number of new acks after RTO */
     343             :         u8      nonagle;        /* Disable Nagle algorithm?             */
     344             : 
     345             : /* RTT measurement */
     346             :         u32     srtt;           /* smoothed round trip time << 3  */
     347             :         u32     mdev;           /* medium deviation                     */
     348             :         u32     mdev_max;       /* maximal mdev for the last rtt period */
     349             :         u32     rttvar;         /* smoothed mdev_max                    */
     350             :         u32     rtt_seq;        /* sequence number to update rttvar     */
     351             : 
     352             :         u32     packets_out;    /* Packets which are "in flight"      */
     353             :         u32     retrans_out;    /* Retransmitted packets out            */
     354             : 
     355             :         u16     urg_data;       /* Saved octet of OOB data and control flags */
     356             :         u8      ecn_flags;      /* ECN status bits.                     */
     357             :         u8      reordering;     /* Packet reordering metric.            */
     358             :         u32     snd_up;         /* Urgent pointer               */
     359             : 
     360             :         u8      keepalive_probes; /* num of allowed keep alive probes   */
     361             : /*
     362             :  *      Options received (usually on last packet, some only on SYN packets).
     363             :  */
     364             :         struct tcp_options_received rx_opt;
     365             : 
     366             : /*
     367             :  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
     368             :  */
     369             :         u32     snd_ssthresh;   /* Slow start size threshold            */
     370             :         u32     snd_cwnd;       /* Sending congestion window            */
     371             :         u32     snd_cwnd_cnt;   /* Linear increase counter              */
     372             :         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
     373             :         u32     snd_cwnd_used;
     374             :         u32     snd_cwnd_stamp;
     375             : 
     376             :         u32     rcv_wnd;        /* Current receiver window              */
     377             :         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
     378             :         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
     379             :         u32     lost_out;       /* Lost packets                 */
     380             :         u32     sacked_out;     /* SACK'd packets                       */
     381             :         u32     fackets_out;    /* FACK'd packets                       */
     382             :         u32     tso_deferred;
     383             :         u32     bytes_acked;    /* Appropriate Byte Counting - RFC3465 */
     384             : 
     385             :         /* from STCP, retrans queue hinting */
     386             :         struct sk_buff* lost_skb_hint;
     387             :         struct sk_buff *scoreboard_skb_hint;
     388             :         struct sk_buff *retransmit_skb_hint;
     389             : 
     390             :         struct sk_buff_head     out_of_order_queue; /* Out of order segments go here */
     391             : 
     392             :         /* SACKs data, these 2 need to be together (see tcp_build_and_update_options) */
     393             :         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
     394             :         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
     395             : 
     396             :         struct tcp_sack_block recv_sack_cache[4];
     397             : 
     398             :         struct sk_buff *highest_sack;   /* highest skb with SACK received
     399             :                                          * (validity guaranteed only if
     400             :                                          * sacked_out > 0)
     401             :                                          */
     402             : 
     403             :         int     lost_cnt_hint;
     404             :         u32     retransmit_high;        /* L-bits may be on up to this seqno */
     405             : 
     406             :         u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
     407             : 
     408             :         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
     409             :         u32     high_seq;       /* snd_nxt at onset of congestion       */
     410             : 
     411             :         u32     retrans_stamp;  /* Timestamp of the last retransmit,
     412             :                                  * also used in SYN-SENT to remember stamp of
     413             :                                  * the first SYN. */
     414             :         u32     undo_marker;    /* tracking retrans started here. */
     415             :         int     undo_retrans;   /* number of undoable retransmissions. */
     416             :         u32     total_retrans;  /* Total retransmits for entire connection */
     417             : 
     418             :         u32     urg_seq;        /* Seq of received urgent pointer */
     419             :         unsigned int            keepalive_time;   /* time before keep alive takes place */
     420             :         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
     421             : 
     422             :         int                     linger2;
     423             : 
     424             : /* Receiver side RTT estimation */
     425             :         struct {
     426             :                 u32     rtt;
     427             :                 u32     seq;
     428             :                 u32     time;
     429             :         } rcv_rtt_est;
     430             : 
     431             : /* Receiver queue space */
     432             :         struct {
     433             :                 int     space;
     434             :                 u32     seq;
     435             :                 u32     time;
     436             :         } rcvq_space;
     437             : 
     438             : /* TCP-specific MTU probe information. */
     439             :         struct {
     440             :                 u32               probe_seq_start;
     441             :                 u32               probe_seq_end;
     442             :         } mtu_probe;
     443             : 
     444             : #ifdef CONFIG_TCP_MD5SIG
     445             : /* TCP AF-Specific parts; only used by MD5 Signature support so far */
     446             :         const struct tcp_sock_af_ops    *af_specific;
     447             : 
     448             : /* TCP MD5 Signature Option information */
     449             :         struct tcp_md5sig_info  *md5sig_info;
     450             : #endif
     451             : 
     452             :         /* When the cookie options are generated and exchanged, then this
     453             :          * object holds a reference to them (cookie_values->kref).  Also
     454             :          * contains related tcp_cookie_transactions fields.
     455             :          */
     456             :         struct tcp_cookie_values  *cookie_values;
     457             : };
     458             : 
     459             : static inline struct tcp_sock *tcp_sk(const struct sock *sk)
     460             : {
     461          10 :         return (struct tcp_sock *)sk;
     462             : }
     463             : 
     464             : struct tcp_timewait_sock {
     465             :         struct inet_timewait_sock tw_sk;
     466             :         u32                       tw_rcv_nxt;
     467             :         u32                       tw_snd_nxt;
     468             :         u32                       tw_rcv_wnd;
     469             :         u32                       tw_ts_recent;
     470             :         long                      tw_ts_recent_stamp;
     471             : #ifdef CONFIG_TCP_MD5SIG
     472             :         u16                       tw_md5_keylen;
     473             :         u8                        tw_md5_key[TCP_MD5SIG_MAXKEYLEN];
     474             : #endif
     475             :         /* Few sockets in timewait have cookies; in that case, then this
     476             :          * object holds a reference to them (tw_cookie_values->kref).
     477             :          */
     478             :         struct tcp_cookie_values  *tw_cookie_values;
     479             : };
     480             : 
     481             : static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
     482             : {
     483             :         return (struct tcp_timewait_sock *)sk;
     484             : }
     485             : 
     486             : #endif  /* __KERNEL__ */
     487             : 
     488             : #endif  /* _LINUX_TCP_H */

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