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, <[email protected]> 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 <linux/dmaengine.h> 23 #include <net/sock.h> 24 #include <net/inet_connection_sock.h> 25 #include <net/inet_timewait_sock.h> 26 #include <uapi/linux/tcp.h> 27 28 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb) 29 { 30 return (struct tcphdr *)skb_transport_header(skb); 31 } 32 33 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb) 34 { 35 return tcp_hdr(skb)->doff * 4; 36 } 37 38 static inline unsigned int tcp_optlen(const struct sk_buff *skb) 39 { 40 return (tcp_hdr(skb)->doff - 5) * 4; 41 } 42 43 /* TCP Fast Open */ 44 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */ 45 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */ 46 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */ 47 48 /* TCP Fast Open Cookie as stored in memory */ 49 struct tcp_fastopen_cookie { 50 s8 len; 51 u8 val[TCP_FASTOPEN_COOKIE_MAX]; 52 }; 53 54 /* This defines a selective acknowledgement block. */ 55 struct tcp_sack_block_wire { 56 __be32 start_seq; 57 __be32 end_seq; 58 }; 59 60 struct tcp_sack_block { 61 u32 start_seq; 62 u32 end_seq; 63 }; 64 65 /*These are used to set the sack_ok field in struct tcp_options_received */ 66 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */ 67 #define TCP_FACK_ENABLED (1 << 1) /*1 = FACK is enabled locally*/ 68 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/ 69 70 struct tcp_options_received { 71 /* PAWS/RTTM data */ 72 long ts_recent_stamp;/* Time we stored ts_recent (for aging) */ 73 u32 ts_recent; /* Time stamp to echo next */ 74 u32 rcv_tsval; /* Time stamp value */ 75 u32 rcv_tsecr; /* Time stamp echo reply */ 76 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */ 77 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */ 78 dsack : 1, /* D-SACK is scheduled */ 79 wscale_ok : 1, /* Wscale seen on SYN packet */ 80 sack_ok : 4, /* SACK seen on SYN packet */ 81 snd_wscale : 4, /* Window scaling received from sender */ 82 rcv_wscale : 4; /* Window scaling to send to receiver */ 83 u8 cookie_plus:6, /* bytes in authenticator/cookie option */ 84 cookie_out_never:1, 85 cookie_in_always:1; 86 u8 num_sacks; /* Number of SACK blocks */ 87 u16 user_mss; /* mss requested by user in ioctl */ 88 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 89 }; 90 91 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 92 { 93 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 94 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 95 rx_opt->cookie_plus = 0; 96 } 97 98 /* This is the max number of SACKS that we'll generate and process. It's safe 99 * to increase this, although since: 100 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 101 * only four options will fit in a standard TCP header */ 102 #define TCP_NUM_SACKS 4 103 104 struct tcp_cookie_values; 105 struct tcp_request_sock_ops; 106 107 struct tcp_request_sock { 108 struct inet_request_sock req; 109 #ifdef CONFIG_TCP_MD5SIG 110 /* Only used by TCP MD5 Signature so far. */ 111 const struct tcp_request_sock_ops *af_specific; 112 #endif 113 struct sock *listener; /* needed for TFO */ 114 u32 rcv_isn; 115 u32 snt_isn; 116 u32 snt_synack; /* synack sent time */ 117 u32 rcv_nxt; /* the ack # by SYNACK. For 118 * FastOpen it's the seq# 119 * after data-in-SYN. 120 */ 121 }; 122 123 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 124 { 125 return (struct tcp_request_sock *)req; 126 } 127 128 struct tcp_sock { 129 /* inet_connection_sock has to be the first member of tcp_sock */ 130 struct inet_connection_sock inet_conn; 131 u16 tcp_header_len; /* Bytes of tcp header to send */ 132 u16 xmit_size_goal_segs; /* Goal for segmenting output packets */ 133 134 /* 135 * Header prediction flags 136 * 0x5?10 << 16 + snd_wnd in net byte order 137 */ 138 __be32 pred_flags; 139 140 /* 141 * RFC793 variables by their proper names. This means you can 142 * read the code and the spec side by side (and laugh ...) 143 * See RFC793 and RFC1122. The RFC writes these in capitals. 144 */ 145 u32 rcv_nxt; /* What we want to receive next */ 146 u32 copied_seq; /* Head of yet unread data */ 147 u32 rcv_wup; /* rcv_nxt on last window update sent */ 148 u32 snd_nxt; /* Next sequence we send */ 149 150 u32 snd_una; /* First byte we want an ack for */ 151 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 152 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 153 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 154 155 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 156 unsigned long tsq_flags; 157 158 /* Data for direct copy to user */ 159 struct { 160 struct sk_buff_head prequeue; 161 struct task_struct *task; 162 struct iovec *iov; 163 int memory; 164 int len; 165 #ifdef CONFIG_NET_DMA 166 /* members for async copy */ 167 struct dma_chan *dma_chan; 168 int wakeup; 169 struct dma_pinned_list *pinned_list; 170 dma_cookie_t dma_cookie; 171 #endif 172 } ucopy; 173 174 u32 snd_wl1; /* Sequence for window update */ 175 u32 snd_wnd; /* The window we expect to receive */ 176 u32 max_window; /* Maximal window ever seen from peer */ 177 u32 mss_cache; /* Cached effective mss, not including SACKS */ 178 179 u32 window_clamp; /* Maximal window to advertise */ 180 u32 rcv_ssthresh; /* Current window clamp */ 181 182 u32 frto_highmark; /* snd_nxt when RTO occurred */ 183 u16 advmss; /* Advertised MSS */ 184 u8 frto_counter; /* Number of new acks after RTO */ 185 u8 nonagle : 4,/* Disable Nagle algorithm? */ 186 thin_lto : 1,/* Use linear timeouts for thin streams */ 187 thin_dupack : 1,/* Fast retransmit on first dupack */ 188 repair : 1, 189 unused : 1; 190 u8 repair_queue; 191 u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */ 192 early_retrans_delayed:1, /* Delayed ER timer installed */ 193 syn_data:1, /* SYN includes data */ 194 syn_fastopen:1; /* SYN includes Fast Open option */ 195 196 /* RTT measurement */ 197 u32 srtt; /* smoothed round trip time << 3 */ 198 u32 mdev; /* medium deviation */ 199 u32 mdev_max; /* maximal mdev for the last rtt period */ 200 u32 rttvar; /* smoothed mdev_max */ 201 u32 rtt_seq; /* sequence number to update rttvar */ 202 203 u32 packets_out; /* Packets which are "in flight" */ 204 u32 retrans_out; /* Retransmitted packets out */ 205 206 u16 urg_data; /* Saved octet of OOB data and control flags */ 207 u8 ecn_flags; /* ECN status bits. */ 208 u8 reordering; /* Packet reordering metric. */ 209 u32 snd_up; /* Urgent pointer */ 210 211 u8 keepalive_probes; /* num of allowed keep alive probes */ 212 /* 213 * Options received (usually on last packet, some only on SYN packets). 214 */ 215 struct tcp_options_received rx_opt; 216 217 /* 218 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 219 */ 220 u32 snd_ssthresh; /* Slow start size threshold */ 221 u32 snd_cwnd; /* Sending congestion window */ 222 u32 snd_cwnd_cnt; /* Linear increase counter */ 223 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 224 u32 snd_cwnd_used; 225 u32 snd_cwnd_stamp; 226 u32 prior_cwnd; /* Congestion window at start of Recovery. */ 227 u32 prr_delivered; /* Number of newly delivered packets to 228 * receiver in Recovery. */ 229 u32 prr_out; /* Total number of pkts sent during Recovery. */ 230 231 u32 rcv_wnd; /* Current receiver window */ 232 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 233 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 234 u32 lost_out; /* Lost packets */ 235 u32 sacked_out; /* SACK'd packets */ 236 u32 fackets_out; /* FACK'd packets */ 237 u32 tso_deferred; 238 u32 bytes_acked; /* Appropriate Byte Counting - RFC3465 */ 239 240 /* from STCP, retrans queue hinting */ 241 struct sk_buff* lost_skb_hint; 242 struct sk_buff *scoreboard_skb_hint; 243 struct sk_buff *retransmit_skb_hint; 244 245 struct sk_buff_head out_of_order_queue; /* Out of order segments go here */ 246 247 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 248 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 249 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 250 251 struct tcp_sack_block recv_sack_cache[4]; 252 253 struct sk_buff *highest_sack; /* skb just after the highest 254 * skb with SACKed bit set 255 * (validity guaranteed only if 256 * sacked_out > 0) 257 */ 258 259 int lost_cnt_hint; 260 u32 retransmit_high; /* L-bits may be on up to this seqno */ 261 262 u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */ 263 264 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 265 u32 high_seq; /* snd_nxt at onset of congestion */ 266 267 u32 retrans_stamp; /* Timestamp of the last retransmit, 268 * also used in SYN-SENT to remember stamp of 269 * the first SYN. */ 270 u32 undo_marker; /* tracking retrans started here. */ 271 int undo_retrans; /* number of undoable retransmissions. */ 272 u32 total_retrans; /* Total retransmits for entire connection */ 273 274 u32 urg_seq; /* Seq of received urgent pointer */ 275 unsigned int keepalive_time; /* time before keep alive takes place */ 276 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 277 278 int linger2; 279 280 /* Receiver side RTT estimation */ 281 struct { 282 u32 rtt; 283 u32 seq; 284 u32 time; 285 } rcv_rtt_est; 286 287 /* Receiver queue space */ 288 struct { 289 int space; 290 u32 seq; 291 u32 time; 292 } rcvq_space; 293 294 /* TCP-specific MTU probe information. */ 295 struct { 296 u32 probe_seq_start; 297 u32 probe_seq_end; 298 } mtu_probe; 299 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 300 * while socket was owned by user. 301 */ 302 303 #ifdef CONFIG_TCP_MD5SIG 304 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 305 const struct tcp_sock_af_ops *af_specific; 306 307 /* TCP MD5 Signature Option information */ 308 struct tcp_md5sig_info __rcu *md5sig_info; 309 #endif 310 311 /* When the cookie options are generated and exchanged, then this 312 * object holds a reference to them (cookie_values->kref). Also 313 * contains related tcp_cookie_transactions fields. 314 */ 315 struct tcp_cookie_values *cookie_values; 316 317 /* TCP fastopen related information */ 318 struct tcp_fastopen_request *fastopen_req; 319 /* fastopen_rsk points to request_sock that resulted in this big 320 * socket. Used to retransmit SYNACKs etc. 321 */ 322 struct request_sock *fastopen_rsk; 323 }; 324 325 enum tsq_flags { 326 TSQ_THROTTLED, 327 TSQ_QUEUED, 328 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 329 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 330 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 331 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 332 * tcp_v{4|6}_mtu_reduced() 333 */ 334 }; 335 336 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 337 { 338 return (struct tcp_sock *)sk; 339 } 340 341 struct tcp_timewait_sock { 342 struct inet_timewait_sock tw_sk; 343 u32 tw_rcv_nxt; 344 u32 tw_snd_nxt; 345 u32 tw_rcv_wnd; 346 u32 tw_ts_recent; 347 long tw_ts_recent_stamp; 348 #ifdef CONFIG_TCP_MD5SIG 349 struct tcp_md5sig_key *tw_md5_key; 350 #endif 351 /* Few sockets in timewait have cookies; in that case, then this 352 * object holds a reference to them (tw_cookie_values->kref). 353 */ 354 struct tcp_cookie_values *tw_cookie_values; 355 }; 356 357 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 358 { 359 return (struct tcp_timewait_sock *)sk; 360 } 361 362 static inline bool tcp_passive_fastopen(const struct sock *sk) 363 { 364 return (sk->sk_state == TCP_SYN_RECV && 365 tcp_sk(sk)->fastopen_rsk != NULL); 366 } 367 368 static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc) 369 { 370 return foc->len != -1; 371 } 372 373 extern void tcp_sock_destruct(struct sock *sk); 374 375 static inline int fastopen_init_queue(struct sock *sk, int backlog) 376 { 377 struct request_sock_queue *queue = 378 &inet_csk(sk)->icsk_accept_queue; 379 380 if (queue->fastopenq == NULL) { 381 queue->fastopenq = kzalloc( 382 sizeof(struct fastopen_queue), 383 sk->sk_allocation); 384 if (queue->fastopenq == NULL) 385 return -ENOMEM; 386 387 sk->sk_destruct = tcp_sock_destruct; 388 spin_lock_init(&queue->fastopenq->lock); 389 } 390 queue->fastopenq->max_qlen = backlog; 391 return 0; 392 } 393 394 #endif /* _LINUX_TCP_H */ 395