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 struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb) 39 { 40 return (struct tcphdr *)skb_inner_transport_header(skb); 41 } 42 43 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb) 44 { 45 return inner_tcp_hdr(skb)->doff * 4; 46 } 47 48 static inline unsigned int tcp_optlen(const struct sk_buff *skb) 49 { 50 return (tcp_hdr(skb)->doff - 5) * 4; 51 } 52 53 /* TCP Fast Open */ 54 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */ 55 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */ 56 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */ 57 58 /* TCP Fast Open Cookie as stored in memory */ 59 struct tcp_fastopen_cookie { 60 s8 len; 61 u8 val[TCP_FASTOPEN_COOKIE_MAX]; 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 cookie_plus:6, /* bytes in authenticator/cookie option */ 94 cookie_out_never:1, 95 cookie_in_always:1; 96 u8 num_sacks; /* Number of SACK blocks */ 97 u16 user_mss; /* mss requested by user in ioctl */ 98 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 99 }; 100 101 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 102 { 103 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 104 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 105 rx_opt->cookie_plus = 0; 106 } 107 108 /* This is the max number of SACKS that we'll generate and process. It's safe 109 * to increase this, although since: 110 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 111 * only four options will fit in a standard TCP header */ 112 #define TCP_NUM_SACKS 4 113 114 struct tcp_cookie_values; 115 struct tcp_request_sock_ops; 116 117 struct tcp_request_sock { 118 struct inet_request_sock req; 119 #ifdef CONFIG_TCP_MD5SIG 120 /* Only used by TCP MD5 Signature so far. */ 121 const struct tcp_request_sock_ops *af_specific; 122 #endif 123 struct sock *listener; /* needed for TFO */ 124 u32 rcv_isn; 125 u32 snt_isn; 126 u32 snt_synack; /* synack sent time */ 127 u32 rcv_nxt; /* the ack # by SYNACK. For 128 * FastOpen it's the seq# 129 * after data-in-SYN. 130 */ 131 }; 132 133 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 134 { 135 return (struct tcp_request_sock *)req; 136 } 137 138 struct tcp_sock { 139 /* inet_connection_sock has to be the first member of tcp_sock */ 140 struct inet_connection_sock inet_conn; 141 u16 tcp_header_len; /* Bytes of tcp header to send */ 142 u16 xmit_size_goal_segs; /* Goal for segmenting output packets */ 143 144 /* 145 * Header prediction flags 146 * 0x5?10 << 16 + snd_wnd in net byte order 147 */ 148 __be32 pred_flags; 149 150 /* 151 * RFC793 variables by their proper names. This means you can 152 * read the code and the spec side by side (and laugh ...) 153 * See RFC793 and RFC1122. The RFC writes these in capitals. 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 */ 159 160 u32 snd_una; /* First byte we want an ack for */ 161 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 162 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 163 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 164 165 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 166 unsigned long tsq_flags; 167 168 /* Data for direct copy to user */ 169 struct { 170 struct sk_buff_head prequeue; 171 struct task_struct *task; 172 struct iovec *iov; 173 int memory; 174 int len; 175 #ifdef CONFIG_NET_DMA 176 /* members for async copy */ 177 struct dma_chan *dma_chan; 178 int wakeup; 179 struct dma_pinned_list *pinned_list; 180 dma_cookie_t dma_cookie; 181 #endif 182 } ucopy; 183 184 u32 snd_wl1; /* Sequence for window update */ 185 u32 snd_wnd; /* The window we expect to receive */ 186 u32 max_window; /* Maximal window ever seen from peer */ 187 u32 mss_cache; /* Cached effective mss, not including SACKS */ 188 189 u32 window_clamp; /* Maximal window to advertise */ 190 u32 rcv_ssthresh; /* Current window clamp */ 191 192 u32 frto_highmark; /* snd_nxt when RTO occurred */ 193 u16 advmss; /* Advertised MSS */ 194 u8 frto_counter; /* Number of new acks after RTO */ 195 u8 nonagle : 4,/* Disable Nagle algorithm? */ 196 thin_lto : 1,/* Use linear timeouts for thin streams */ 197 thin_dupack : 1,/* Fast retransmit on first dupack */ 198 repair : 1, 199 unused : 1; 200 u8 repair_queue; 201 u8 do_early_retrans:1,/* Enable RFC5827 early-retransmit */ 202 early_retrans_delayed:1, /* Delayed ER timer installed */ 203 syn_data:1, /* SYN includes data */ 204 syn_fastopen:1, /* SYN includes Fast Open option */ 205 syn_data_acked:1;/* data in SYN is acked by SYN-ACK */ 206 207 /* RTT measurement */ 208 u32 srtt; /* smoothed round trip time << 3 */ 209 u32 mdev; /* medium deviation */ 210 u32 mdev_max; /* maximal mdev for the last rtt period */ 211 u32 rttvar; /* smoothed mdev_max */ 212 u32 rtt_seq; /* sequence number to update rttvar */ 213 214 u32 packets_out; /* Packets which are "in flight" */ 215 u32 retrans_out; /* Retransmitted packets out */ 216 217 u16 urg_data; /* Saved octet of OOB data and control flags */ 218 u8 ecn_flags; /* ECN status bits. */ 219 u8 reordering; /* Packet reordering metric. */ 220 u32 snd_up; /* Urgent pointer */ 221 222 u8 keepalive_probes; /* num of allowed keep alive probes */ 223 /* 224 * Options received (usually on last packet, some only on SYN packets). 225 */ 226 struct tcp_options_received rx_opt; 227 228 /* 229 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 230 */ 231 u32 snd_ssthresh; /* Slow start size threshold */ 232 u32 snd_cwnd; /* Sending congestion window */ 233 u32 snd_cwnd_cnt; /* Linear increase counter */ 234 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 235 u32 snd_cwnd_used; 236 u32 snd_cwnd_stamp; 237 u32 prior_cwnd; /* Congestion window at start of Recovery. */ 238 u32 prr_delivered; /* Number of newly delivered packets to 239 * receiver in Recovery. */ 240 u32 prr_out; /* Total number of pkts sent during Recovery. */ 241 242 u32 rcv_wnd; /* Current receiver window */ 243 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 244 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 245 u32 lost_out; /* Lost packets */ 246 u32 sacked_out; /* SACK'd packets */ 247 u32 fackets_out; /* FACK'd packets */ 248 u32 tso_deferred; 249 u32 bytes_acked; /* Appropriate Byte Counting - RFC3465 */ 250 251 /* from STCP, retrans queue hinting */ 252 struct sk_buff* lost_skb_hint; 253 struct sk_buff *scoreboard_skb_hint; 254 struct sk_buff *retransmit_skb_hint; 255 256 struct sk_buff_head out_of_order_queue; /* Out of order segments go here */ 257 258 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 259 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 260 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 261 262 struct tcp_sack_block recv_sack_cache[4]; 263 264 struct sk_buff *highest_sack; /* skb just after the highest 265 * skb with SACKed bit set 266 * (validity guaranteed only if 267 * sacked_out > 0) 268 */ 269 270 int lost_cnt_hint; 271 u32 retransmit_high; /* L-bits may be on up to this seqno */ 272 273 u32 lost_retrans_low; /* Sent seq after any rxmit (lowest) */ 274 275 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 276 u32 high_seq; /* snd_nxt at onset of congestion */ 277 278 u32 retrans_stamp; /* Timestamp of the last retransmit, 279 * also used in SYN-SENT to remember stamp of 280 * the first SYN. */ 281 u32 undo_marker; /* tracking retrans started here. */ 282 int undo_retrans; /* number of undoable retransmissions. */ 283 u32 total_retrans; /* Total retransmits for entire connection */ 284 285 u32 urg_seq; /* Seq of received urgent pointer */ 286 unsigned int keepalive_time; /* time before keep alive takes place */ 287 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 288 289 int linger2; 290 291 /* Receiver side RTT estimation */ 292 struct { 293 u32 rtt; 294 u32 seq; 295 u32 time; 296 } rcv_rtt_est; 297 298 /* Receiver queue space */ 299 struct { 300 int space; 301 u32 seq; 302 u32 time; 303 } rcvq_space; 304 305 /* TCP-specific MTU probe information. */ 306 struct { 307 u32 probe_seq_start; 308 u32 probe_seq_end; 309 } mtu_probe; 310 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 311 * while socket was owned by user. 312 */ 313 314 #ifdef CONFIG_TCP_MD5SIG 315 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 316 const struct tcp_sock_af_ops *af_specific; 317 318 /* TCP MD5 Signature Option information */ 319 struct tcp_md5sig_info __rcu *md5sig_info; 320 #endif 321 322 /* When the cookie options are generated and exchanged, then this 323 * object holds a reference to them (cookie_values->kref). Also 324 * contains related tcp_cookie_transactions fields. 325 */ 326 struct tcp_cookie_values *cookie_values; 327 328 /* TCP fastopen related information */ 329 struct tcp_fastopen_request *fastopen_req; 330 /* fastopen_rsk points to request_sock that resulted in this big 331 * socket. Used to retransmit SYNACKs etc. 332 */ 333 struct request_sock *fastopen_rsk; 334 }; 335 336 enum tsq_flags { 337 TSQ_THROTTLED, 338 TSQ_QUEUED, 339 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 340 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 341 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 342 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 343 * tcp_v{4|6}_mtu_reduced() 344 */ 345 }; 346 347 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 348 { 349 return (struct tcp_sock *)sk; 350 } 351 352 struct tcp_timewait_sock { 353 struct inet_timewait_sock tw_sk; 354 u32 tw_rcv_nxt; 355 u32 tw_snd_nxt; 356 u32 tw_rcv_wnd; 357 u32 tw_ts_recent; 358 long tw_ts_recent_stamp; 359 #ifdef CONFIG_TCP_MD5SIG 360 struct tcp_md5sig_key *tw_md5_key; 361 #endif 362 /* Few sockets in timewait have cookies; in that case, then this 363 * object holds a reference to them (tw_cookie_values->kref). 364 */ 365 struct tcp_cookie_values *tw_cookie_values; 366 }; 367 368 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 369 { 370 return (struct tcp_timewait_sock *)sk; 371 } 372 373 static inline bool tcp_passive_fastopen(const struct sock *sk) 374 { 375 return (sk->sk_state == TCP_SYN_RECV && 376 tcp_sk(sk)->fastopen_rsk != NULL); 377 } 378 379 static inline bool fastopen_cookie_present(struct tcp_fastopen_cookie *foc) 380 { 381 return foc->len != -1; 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 #endif /* _LINUX_TCP_H */ 406