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TOMOYO Linux Cross Reference
Linux/include/linux/tcp.h

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  1 /*
  2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
  3  *              operating system.  INET is implemented using the  BSD Socket
  4  *              interface as the means of communication with the user level.
  5  *
  6  *              Definitions for the TCP protocol.
  7  *
  8  * Version:     @(#)tcp.h       1.0.2   04/28/93
  9  *
 10  * Author:      Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 11  *
 12  *              This program is free software; you can redistribute it and/or
 13  *              modify it under the terms of the GNU General Public License
 14  *              as published by the Free Software Foundation; either version
 15  *              2 of the License, or (at your option) any later version.
 16  */
 17 #ifndef _LINUX_TCP_H
 18 #define _LINUX_TCP_H
 19 
 20 
 21 #include <linux/skbuff.h>
 22 #include <net/sock.h>
 23 #include <net/inet_connection_sock.h>
 24 #include <net/inet_timewait_sock.h>
 25 #include <uapi/linux/tcp.h>
 26 
 27 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb)
 28 {
 29         return (struct tcphdr *)skb_transport_header(skb);
 30 }
 31 
 32 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb)
 33 {
 34         return tcp_hdr(skb)->doff * 4;
 35 }
 36 
 37 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb)
 38 {
 39         return (struct tcphdr *)skb_inner_transport_header(skb);
 40 }
 41 
 42 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb)
 43 {
 44         return inner_tcp_hdr(skb)->doff * 4;
 45 }
 46 
 47 static inline unsigned int tcp_optlen(const struct sk_buff *skb)
 48 {
 49         return (tcp_hdr(skb)->doff - 5) * 4;
 50 }
 51 
 52 /* TCP Fast Open */
 53 #define TCP_FASTOPEN_COOKIE_MIN 4       /* Min Fast Open Cookie size in bytes */
 54 #define TCP_FASTOPEN_COOKIE_MAX 16      /* Max Fast Open Cookie size in bytes */
 55 #define TCP_FASTOPEN_COOKIE_SIZE 8      /* the size employed by this impl. */
 56 
 57 /* TCP Fast Open Cookie as stored in memory */
 58 struct tcp_fastopen_cookie {
 59         s8      len;
 60         u8      val[TCP_FASTOPEN_COOKIE_MAX];
 61         bool    exp;    /* In RFC6994 experimental option format */
 62 };
 63 
 64 /* This defines a selective acknowledgement block. */
 65 struct tcp_sack_block_wire {
 66         __be32  start_seq;
 67         __be32  end_seq;
 68 };
 69 
 70 struct tcp_sack_block {
 71         u32     start_seq;
 72         u32     end_seq;
 73 };
 74 
 75 /*These are used to set the sack_ok field in struct tcp_options_received */
 76 #define TCP_SACK_SEEN     (1 << 0)   /*1 = peer is SACK capable, */
 77 #define TCP_FACK_ENABLED  (1 << 1)   /*1 = FACK is enabled locally*/
 78 #define TCP_DSACK_SEEN    (1 << 2)   /*1 = DSACK was received from peer*/
 79 
 80 struct tcp_options_received {
 81 /*      PAWS/RTTM data  */
 82         long    ts_recent_stamp;/* Time we stored ts_recent (for aging) */
 83         u32     ts_recent;      /* Time stamp to echo next              */
 84         u32     rcv_tsval;      /* Time stamp value                     */
 85         u32     rcv_tsecr;      /* Time stamp echo reply                */
 86         u16     saw_tstamp : 1, /* Saw TIMESTAMP on last packet         */
 87                 tstamp_ok : 1,  /* TIMESTAMP seen on SYN packet         */
 88                 dsack : 1,      /* D-SACK is scheduled                  */
 89                 wscale_ok : 1,  /* Wscale seen on SYN packet            */
 90                 sack_ok : 4,    /* SACK seen on SYN packet              */
 91                 snd_wscale : 4, /* Window scaling received from sender  */
 92                 rcv_wscale : 4; /* Window scaling to send to receiver   */
 93         u8      num_sacks;      /* Number of SACK blocks                */
 94         u16     user_mss;       /* mss requested by user in ioctl       */
 95         u16     mss_clamp;      /* Maximal mss, negotiated at connection setup */
 96 };
 97 
 98 static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
 99 {
100         rx_opt->tstamp_ok = rx_opt->sack_ok = 0;
101         rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
102 }
103 
104 /* This is the max number of SACKS that we'll generate and process. It's safe
105  * to increase this, although since:
106  *   size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8)
107  * only four options will fit in a standard TCP header */
108 #define TCP_NUM_SACKS 4
109 
110 struct tcp_request_sock_ops;
111 
112 struct tcp_request_sock {
113         struct inet_request_sock        req;
114         const struct tcp_request_sock_ops *af_specific;
115         bool                            tfo_listener;
116         u32                             rcv_isn;
117         u32                             snt_isn;
118         u32                             snt_synack; /* synack sent time */
119         u32                             last_oow_ack_time; /* last SYNACK */
120         u32                             rcv_nxt; /* the ack # by SYNACK. For
121                                                   * FastOpen it's the seq#
122                                                   * after data-in-SYN.
123                                                   */
124 };
125 
126 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req)
127 {
128         return (struct tcp_request_sock *)req;
129 }
130 
131 struct tcp_sock {
132         /* inet_connection_sock has to be the first member of tcp_sock */
133         struct inet_connection_sock     inet_conn;
134         u16     tcp_header_len; /* Bytes of tcp header to send          */
135         u16     gso_segs;       /* Max number of segs per GSO packet    */
136 
137 /*
138  *      Header prediction flags
139  *      0x5?10 << 16 + snd_wnd in net byte order
140  */
141         __be32  pred_flags;
142 
143 /*
144  *      RFC793 variables by their proper names. This means you can
145  *      read the code and the spec side by side (and laugh ...)
146  *      See RFC793 and RFC1122. The RFC writes these in capitals.
147  */
148         u64     bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived
149                                  * sum(delta(rcv_nxt)), or how many bytes
150                                  * were acked.
151                                  */
152         u32     segs_in;        /* RFC4898 tcpEStatsPerfSegsIn
153                                  * total number of segments in.
154                                  */
155         u32     rcv_nxt;        /* What we want to receive next         */
156         u32     copied_seq;     /* Head of yet unread data              */
157         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
158         u32     snd_nxt;        /* Next sequence we send                */
159         u32     segs_out;       /* RFC4898 tcpEStatsPerfSegsOut
160                                  * The total number of segments sent.
161                                  */
162         u64     bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked
163                                  * sum(delta(snd_una)), or how many bytes
164                                  * were acked.
165                                  */
166         struct u64_stats_sync syncp; /* protects 64bit vars (cf tcp_get_info()) */
167 
168         u32     snd_una;        /* First byte we want an ack for        */
169         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
170         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
171         u32     lsndtime;       /* timestamp of last sent data packet (for restart window) */
172         u32     last_oow_ack_time;  /* timestamp of last out-of-window ACK */
173 
174         u32     tsoffset;       /* timestamp offset */
175 
176         struct list_head tsq_node; /* anchor in tsq_tasklet.head list */
177         unsigned long   tsq_flags;
178 
179         /* Data for direct copy to user */
180         struct {
181                 struct sk_buff_head     prequeue;
182                 struct task_struct      *task;
183                 struct msghdr           *msg;
184                 int                     memory;
185                 int                     len;
186         } ucopy;
187 
188         u32     snd_wl1;        /* Sequence for window update           */
189         u32     snd_wnd;        /* The window we expect to receive      */
190         u32     max_window;     /* Maximal window ever seen from peer   */
191         u32     mss_cache;      /* Cached effective mss, not including SACKS */
192 
193         u32     window_clamp;   /* Maximal window to advertise          */
194         u32     rcv_ssthresh;   /* Current window clamp                 */
195 
196         u16     advmss;         /* Advertised MSS                       */
197         u8      unused;
198         u8      nonagle     : 4,/* Disable Nagle algorithm?             */
199                 thin_lto    : 1,/* Use linear timeouts for thin streams */
200                 thin_dupack : 1,/* Fast retransmit on first dupack      */
201                 repair      : 1,
202                 frto        : 1;/* F-RTO (RFC5682) activated in CA_Loss */
203         u8      repair_queue;
204         u8      do_early_retrans:1,/* Enable RFC5827 early-retransmit  */
205                 syn_data:1,     /* SYN includes data */
206                 syn_fastopen:1, /* SYN includes Fast Open option */
207                 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */
208                 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */
209                 save_syn:1,     /* Save headers of SYN packet */
210                 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */
211         u32     tlp_high_seq;   /* snd_nxt at the time of TLP retransmit. */
212 
213 /* RTT measurement */
214         u32     srtt_us;        /* smoothed round trip time << 3 in usecs */
215         u32     mdev_us;        /* medium deviation                     */
216         u32     mdev_max_us;    /* maximal mdev for the last rtt period */
217         u32     rttvar_us;      /* smoothed mdev_max                    */
218         u32     rtt_seq;        /* sequence number to update rttvar     */
219 
220         u32     packets_out;    /* Packets which are "in flight"        */
221         u32     retrans_out;    /* Retransmitted packets out            */
222         u32     max_packets_out;  /* max packets_out in last window */
223         u32     max_packets_seq;  /* right edge of max_packets_out flight */
224 
225         u16     urg_data;       /* Saved octet of OOB data and control flags */
226         u8      ecn_flags;      /* ECN status bits.                     */
227         u8      keepalive_probes; /* num of allowed keep alive probes   */
228         u32     reordering;     /* Packet reordering metric.            */
229         u32     snd_up;         /* Urgent pointer               */
230 
231 /*
232  *      Options received (usually on last packet, some only on SYN packets).
233  */
234         struct tcp_options_received rx_opt;
235 
236 /*
237  *      Slow start and congestion control (see also Nagle, and Karn & Partridge)
238  */
239         u32     snd_ssthresh;   /* Slow start size threshold            */
240         u32     snd_cwnd;       /* Sending congestion window            */
241         u32     snd_cwnd_cnt;   /* Linear increase counter              */
242         u32     snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */
243         u32     snd_cwnd_used;
244         u32     snd_cwnd_stamp;
245         u32     prior_cwnd;     /* Congestion window at start of Recovery. */
246         u32     prr_delivered;  /* Number of newly delivered packets to
247                                  * receiver in Recovery. */
248         u32     prr_out;        /* Total number of pkts sent during Recovery. */
249 
250         u32     rcv_wnd;        /* Current receiver window              */
251         u32     write_seq;      /* Tail(+1) of data held in tcp send buffer */
252         u32     notsent_lowat;  /* TCP_NOTSENT_LOWAT */
253         u32     pushed_seq;     /* Last pushed seq, required to talk to windows */
254         u32     lost_out;       /* Lost packets                 */
255         u32     sacked_out;     /* SACK'd packets                       */
256         u32     fackets_out;    /* FACK'd packets                       */
257 
258         /* from STCP, retrans queue hinting */
259         struct sk_buff* lost_skb_hint;
260         struct sk_buff *retransmit_skb_hint;
261 
262         /* OOO segments go in this list. Note that socket lock must be held,
263          * as we do not use sk_buff_head lock.
264          */
265         struct sk_buff_head     out_of_order_queue;
266 
267         /* SACKs data, these 2 need to be together (see tcp_options_write) */
268         struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */
269         struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/
270 
271         struct tcp_sack_block recv_sack_cache[4];
272 
273         struct sk_buff *highest_sack;   /* skb just after the highest
274                                          * skb with SACKed bit set
275                                          * (validity guaranteed only if
276                                          * sacked_out > 0)
277                                          */
278 
279         int     lost_cnt_hint;
280         u32     retransmit_high;        /* L-bits may be on up to this seqno */
281 
282         u32     lost_retrans_low;       /* Sent seq after any rxmit (lowest) */
283 
284         u32     prior_ssthresh; /* ssthresh saved at recovery start     */
285         u32     high_seq;       /* snd_nxt at onset of congestion       */
286 
287         u32     retrans_stamp;  /* Timestamp of the last retransmit,
288                                  * also used in SYN-SENT to remember stamp of
289                                  * the first SYN. */
290         u32     undo_marker;    /* snd_una upon a new recovery episode. */
291         int     undo_retrans;   /* number of undoable retransmissions. */
292         u32     total_retrans;  /* Total retransmits for entire connection */
293 
294         u32     urg_seq;        /* Seq of received urgent pointer */
295         unsigned int            keepalive_time;   /* time before keep alive takes place */
296         unsigned int            keepalive_intvl;  /* time interval between keep alive probes */
297 
298         int                     linger2;
299 
300 /* Receiver side RTT estimation */
301         struct {
302                 u32     rtt;
303                 u32     seq;
304                 u32     time;
305         } rcv_rtt_est;
306 
307 /* Receiver queue space */
308         struct {
309                 int     space;
310                 u32     seq;
311                 u32     time;
312         } rcvq_space;
313 
314 /* TCP-specific MTU probe information. */
315         struct {
316                 u32               probe_seq_start;
317                 u32               probe_seq_end;
318         } mtu_probe;
319         u32     mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG
320                            * while socket was owned by user.
321                            */
322 
323 #ifdef CONFIG_TCP_MD5SIG
324 /* TCP AF-Specific parts; only used by MD5 Signature support so far */
325         const struct tcp_sock_af_ops    *af_specific;
326 
327 /* TCP MD5 Signature Option information */
328         struct tcp_md5sig_info  __rcu *md5sig_info;
329 #endif
330 
331 /* TCP fastopen related information */
332         struct tcp_fastopen_request *fastopen_req;
333         /* fastopen_rsk points to request_sock that resulted in this big
334          * socket. Used to retransmit SYNACKs etc.
335          */
336         struct request_sock *fastopen_rsk;
337         u32     *saved_syn;
338 };
339 
340 enum tsq_flags {
341         TSQ_THROTTLED,
342         TSQ_QUEUED,
343         TCP_TSQ_DEFERRED,          /* tcp_tasklet_func() found socket was owned */
344         TCP_WRITE_TIMER_DEFERRED,  /* tcp_write_timer() found socket was owned */
345         TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */
346         TCP_MTU_REDUCED_DEFERRED,  /* tcp_v{4|6}_err() could not call
347                                     * tcp_v{4|6}_mtu_reduced()
348                                     */
349 };
350 
351 static inline struct tcp_sock *tcp_sk(const struct sock *sk)
352 {
353         return (struct tcp_sock *)sk;
354 }
355 
356 struct tcp_timewait_sock {
357         struct inet_timewait_sock tw_sk;
358         u32                       tw_rcv_nxt;
359         u32                       tw_snd_nxt;
360         u32                       tw_rcv_wnd;
361         u32                       tw_ts_offset;
362         u32                       tw_ts_recent;
363 
364         /* The time we sent the last out-of-window ACK: */
365         u32                       tw_last_oow_ack_time;
366 
367         long                      tw_ts_recent_stamp;
368 #ifdef CONFIG_TCP_MD5SIG
369         struct tcp_md5sig_key     *tw_md5_key;
370 #endif
371 };
372 
373 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
374 {
375         return (struct tcp_timewait_sock *)sk;
376 }
377 
378 static inline bool tcp_passive_fastopen(const struct sock *sk)
379 {
380         return (sk->sk_state == TCP_SYN_RECV &&
381                 tcp_sk(sk)->fastopen_rsk != NULL);
382 }
383 
384 extern void tcp_sock_destruct(struct sock *sk);
385 
386 static inline int fastopen_init_queue(struct sock *sk, int backlog)
387 {
388         struct request_sock_queue *queue =
389             &inet_csk(sk)->icsk_accept_queue;
390 
391         if (queue->fastopenq == NULL) {
392                 queue->fastopenq = kzalloc(
393                     sizeof(struct fastopen_queue),
394                     sk->sk_allocation);
395                 if (queue->fastopenq == NULL)
396                         return -ENOMEM;
397 
398                 sk->sk_destruct = tcp_sock_destruct;
399                 spin_lock_init(&queue->fastopenq->lock);
400         }
401         queue->fastopenq->max_qlen = backlog;
402         return 0;
403 }
404 
405 static inline void tcp_saved_syn_free(struct tcp_sock *tp)
406 {
407         kfree(tp->saved_syn);
408         tp->saved_syn = NULL;
409 }
410 
411 #endif  /* _LINUX_TCP_H */
412 

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