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