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1 office 1 /**
2 * @file
3 * TCP internal implementations (do not use in application code)
4 */
5  
6 /*
7 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without modification,
11 * are permitted provided that the following conditions are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright notice,
14 * this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 * derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
22 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
23 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
24 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
25 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
26 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
29 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
30 * OF SUCH DAMAGE.
31 *
32 * This file is part of the lwIP TCP/IP stack.
33 *
34 * Author: Adam Dunkels <adam@sics.se>
35 *
36 */
37 #ifndef LWIP_HDR_TCP_PRIV_H
38 #define LWIP_HDR_TCP_PRIV_H
39  
40 #include "lwip/opt.h"
41  
42 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
43  
44 #include "lwip/tcp.h"
45 #include "lwip/mem.h"
46 #include "lwip/pbuf.h"
47 #include "lwip/ip.h"
48 #include "lwip/icmp.h"
49 #include "lwip/err.h"
50 #include "lwip/ip6.h"
51 #include "lwip/ip6_addr.h"
52 #include "lwip/prot/tcp.h"
53  
54 #ifdef __cplusplus
55 extern "C" {
56 #endif
57  
58 /* Functions for interfacing with TCP: */
59  
60 /* Lower layer interface to TCP: */
61 void tcp_init (void); /* Initialize this module. */
62 void tcp_tmr (void); /* Must be called every
63 TCP_TMR_INTERVAL
64 ms. (Typically 250 ms). */
65 /* It is also possible to call these two functions at the right
66 intervals (instead of calling tcp_tmr()). */
67 void tcp_slowtmr (void);
68 void tcp_fasttmr (void);
69  
70 /* Call this from a netif driver (watch out for threading issues!) that has
71 returned a memory error on transmit and now has free buffers to send more.
72 This iterates all active pcbs that had an error and tries to call
73 tcp_output, so use this with care as it might slow down the system. */
74 void tcp_txnow (void);
75  
76 /* Only used by IP to pass a TCP segment to TCP: */
77 void tcp_input (struct pbuf *p, struct netif *inp);
78 /* Used within the TCP code only: */
79 struct tcp_pcb * tcp_alloc (u8_t prio);
80 void tcp_abandon (struct tcp_pcb *pcb, int reset);
81 err_t tcp_send_empty_ack(struct tcp_pcb *pcb);
82 err_t tcp_rexmit (struct tcp_pcb *pcb);
83 err_t tcp_rexmit_rto_prepare(struct tcp_pcb *pcb);
84 void tcp_rexmit_rto_commit(struct tcp_pcb *pcb);
85 void tcp_rexmit_rto (struct tcp_pcb *pcb);
86 void tcp_rexmit_fast (struct tcp_pcb *pcb);
87 u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb);
88 err_t tcp_process_refused_data(struct tcp_pcb *pcb);
89  
90 /**
91 * This is the Nagle algorithm: try to combine user data to send as few TCP
92 * segments as possible. Only send if
93 * - no previously transmitted data on the connection remains unacknowledged or
94 * - the TF_NODELAY flag is set (nagle algorithm turned off for this pcb) or
95 * - the only unsent segment is at least pcb->mss bytes long (or there is more
96 * than one unsent segment - with lwIP, this can happen although unsent->len < mss)
97 * - or if we are in fast-retransmit (TF_INFR)
98 */
99 #define tcp_do_output_nagle(tpcb) ((((tpcb)->unacked == NULL) || \
100 ((tpcb)->flags & (TF_NODELAY | TF_INFR)) || \
101 (((tpcb)->unsent != NULL) && (((tpcb)->unsent->next != NULL) || \
102 ((tpcb)->unsent->len >= (tpcb)->mss))) || \
103 ((tcp_sndbuf(tpcb) == 0) || (tcp_sndqueuelen(tpcb) >= TCP_SND_QUEUELEN)) \
104 ) ? 1 : 0)
105 #define tcp_output_nagle(tpcb) (tcp_do_output_nagle(tpcb) ? tcp_output(tpcb) : ERR_OK)
106  
107  
108 #define TCP_SEQ_LT(a,b) ((s32_t)((u32_t)(a) - (u32_t)(b)) < 0)
109 #define TCP_SEQ_LEQ(a,b) ((s32_t)((u32_t)(a) - (u32_t)(b)) <= 0)
110 #define TCP_SEQ_GT(a,b) ((s32_t)((u32_t)(a) - (u32_t)(b)) > 0)
111 #define TCP_SEQ_GEQ(a,b) ((s32_t)((u32_t)(a) - (u32_t)(b)) >= 0)
112 /* is b<=a<=c? */
113 #if 0 /* see bug #10548 */
114 #define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
115 #endif
116 #define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
117  
118 #ifndef TCP_TMR_INTERVAL
119 #define TCP_TMR_INTERVAL 250 /* The TCP timer interval in milliseconds. */
120 #endif /* TCP_TMR_INTERVAL */
121  
122 #ifndef TCP_FAST_INTERVAL
123 #define TCP_FAST_INTERVAL TCP_TMR_INTERVAL /* the fine grained timeout in milliseconds */
124 #endif /* TCP_FAST_INTERVAL */
125  
126 #ifndef TCP_SLOW_INTERVAL
127 #define TCP_SLOW_INTERVAL (2*TCP_TMR_INTERVAL) /* the coarse grained timeout in milliseconds */
128 #endif /* TCP_SLOW_INTERVAL */
129  
130 #define TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */
131 #define TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */
132  
133 #define TCP_OOSEQ_TIMEOUT 6U /* x RTO */
134  
135 #ifndef TCP_MSL
136 #define TCP_MSL 60000UL /* The maximum segment lifetime in milliseconds */
137 #endif
138  
139 /* Keepalive values, compliant with RFC 1122. Don't change this unless you know what you're doing */
140 #ifndef TCP_KEEPIDLE_DEFAULT
141 #define TCP_KEEPIDLE_DEFAULT 7200000UL /* Default KEEPALIVE timer in milliseconds */
142 #endif
143  
144 #ifndef TCP_KEEPINTVL_DEFAULT
145 #define TCP_KEEPINTVL_DEFAULT 75000UL /* Default Time between KEEPALIVE probes in milliseconds */
146 #endif
147  
148 #ifndef TCP_KEEPCNT_DEFAULT
149 #define TCP_KEEPCNT_DEFAULT 9U /* Default Counter for KEEPALIVE probes */
150 #endif
151  
152 #define TCP_MAXIDLE TCP_KEEPCNT_DEFAULT * TCP_KEEPINTVL_DEFAULT /* Maximum KEEPALIVE probe time */
153  
154 #define TCP_TCPLEN(seg) ((seg)->len + (((TCPH_FLAGS((seg)->tcphdr) & (TCP_FIN | TCP_SYN)) != 0) ? 1U : 0U))
155  
156 /** Flags used on input processing, not on pcb->flags
157 */
158 #define TF_RESET (u8_t)0x08U /* Connection was reset. */
159 #define TF_CLOSED (u8_t)0x10U /* Connection was successfully closed. */
160 #define TF_GOT_FIN (u8_t)0x20U /* Connection was closed by the remote end. */
161  
162  
163 #if LWIP_EVENT_API
164  
165 #define TCP_EVENT_ACCEPT(lpcb,pcb,arg,err,ret) ret = lwip_tcp_event(arg, (pcb),\
166 LWIP_EVENT_ACCEPT, NULL, 0, err)
167 #define TCP_EVENT_SENT(pcb,space,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
168 LWIP_EVENT_SENT, NULL, space, ERR_OK)
169 #define TCP_EVENT_RECV(pcb,p,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
170 LWIP_EVENT_RECV, (p), 0, (err))
171 #define TCP_EVENT_CLOSED(pcb,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
172 LWIP_EVENT_RECV, NULL, 0, ERR_OK)
173 #define TCP_EVENT_CONNECTED(pcb,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
174 LWIP_EVENT_CONNECTED, NULL, 0, (err))
175 #define TCP_EVENT_POLL(pcb,ret) do { if ((pcb)->state != SYN_RCVD) { \
176 ret = lwip_tcp_event((pcb)->callback_arg, (pcb), LWIP_EVENT_POLL, NULL, 0, ERR_OK); \
177 } else { \
178 ret = ERR_ARG; } } while(0)
179 #define TCP_EVENT_ERR(last_state,errf,arg,err) do { if (last_state != SYN_RCVD) { \
180 lwip_tcp_event((arg), NULL, LWIP_EVENT_ERR, NULL, 0, (err)); } } while(0)
181  
182 #else /* LWIP_EVENT_API */
183  
184 #define TCP_EVENT_ACCEPT(lpcb,pcb,arg,err,ret) \
185 do { \
186 if((lpcb)->accept != NULL) \
187 (ret) = (lpcb)->accept((arg),(pcb),(err)); \
188 else (ret) = ERR_ARG; \
189 } while (0)
190  
191 #define TCP_EVENT_SENT(pcb,space,ret) \
192 do { \
193 if((pcb)->sent != NULL) \
194 (ret) = (pcb)->sent((pcb)->callback_arg,(pcb),(space)); \
195 else (ret) = ERR_OK; \
196 } while (0)
197  
198 #define TCP_EVENT_RECV(pcb,p,err,ret) \
199 do { \
200 if((pcb)->recv != NULL) { \
201 (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err));\
202 } else { \
203 (ret) = tcp_recv_null(NULL, (pcb), (p), (err)); \
204 } \
205 } while (0)
206  
207 #define TCP_EVENT_CLOSED(pcb,ret) \
208 do { \
209 if(((pcb)->recv != NULL)) { \
210 (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),NULL,ERR_OK);\
211 } else { \
212 (ret) = ERR_OK; \
213 } \
214 } while (0)
215  
216 #define TCP_EVENT_CONNECTED(pcb,err,ret) \
217 do { \
218 if((pcb)->connected != NULL) \
219 (ret) = (pcb)->connected((pcb)->callback_arg,(pcb),(err)); \
220 else (ret) = ERR_OK; \
221 } while (0)
222  
223 #define TCP_EVENT_POLL(pcb,ret) \
224 do { \
225 if((pcb)->poll != NULL) \
226 (ret) = (pcb)->poll((pcb)->callback_arg,(pcb)); \
227 else (ret) = ERR_OK; \
228 } while (0)
229  
230 #define TCP_EVENT_ERR(last_state,errf,arg,err) \
231 do { \
232 LWIP_UNUSED_ARG(last_state); \
233 if((errf) != NULL) \
234 (errf)((arg),(err)); \
235 } while (0)
236  
237 #endif /* LWIP_EVENT_API */
238  
239 /** Enabled extra-check for TCP_OVERSIZE if LWIP_DEBUG is enabled */
240 #if TCP_OVERSIZE && defined(LWIP_DEBUG)
241 #define TCP_OVERSIZE_DBGCHECK 1
242 #else
243 #define TCP_OVERSIZE_DBGCHECK 0
244 #endif
245  
246 /** Don't generate checksum on copy if CHECKSUM_GEN_TCP is disabled */
247 #define TCP_CHECKSUM_ON_COPY (LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_TCP)
248  
249 /* This structure represents a TCP segment on the unsent, unacked and ooseq queues */
250 struct tcp_seg {
251 struct tcp_seg *next; /* used when putting segments on a queue */
252 struct pbuf *p; /* buffer containing data + TCP header */
253 u16_t len; /* the TCP length of this segment */
254 #if TCP_OVERSIZE_DBGCHECK
255 u16_t oversize_left; /* Extra bytes available at the end of the last
256 pbuf in unsent (used for asserting vs.
257 tcp_pcb.unsent_oversize only) */
258 #endif /* TCP_OVERSIZE_DBGCHECK */
259 #if TCP_CHECKSUM_ON_COPY
260 u16_t chksum;
261 u8_t chksum_swapped;
262 #endif /* TCP_CHECKSUM_ON_COPY */
263 u8_t flags;
264 #define TF_SEG_OPTS_MSS (u8_t)0x01U /* Include MSS option. */
265 #define TF_SEG_OPTS_TS (u8_t)0x02U /* Include timestamp option. */
266 #define TF_SEG_DATA_CHECKSUMMED (u8_t)0x04U /* ALL data (not the header) is
267 checksummed into 'chksum' */
268 #define TF_SEG_OPTS_WND_SCALE (u8_t)0x08U /* Include WND SCALE option */
269 #define TF_SEG_OPTS_SACK_PERM (u8_t)0x10U /* Include SACK Permitted option */
270 struct tcp_hdr *tcphdr; /* the TCP header */
271 };
272  
273 #define LWIP_TCP_OPT_EOL 0
274 #define LWIP_TCP_OPT_NOP 1
275 #define LWIP_TCP_OPT_MSS 2
276 #define LWIP_TCP_OPT_WS 3
277 #define LWIP_TCP_OPT_SACK_PERM 4
278 #define LWIP_TCP_OPT_TS 8
279  
280 #define LWIP_TCP_OPT_LEN_MSS 4
281 #if LWIP_TCP_TIMESTAMPS
282 #define LWIP_TCP_OPT_LEN_TS 10
283 #define LWIP_TCP_OPT_LEN_TS_OUT 12 /* aligned for output (includes NOP padding) */
284 #else
285 #define LWIP_TCP_OPT_LEN_TS_OUT 0
286 #endif
287 #if LWIP_WND_SCALE
288 #define LWIP_TCP_OPT_LEN_WS 3
289 #define LWIP_TCP_OPT_LEN_WS_OUT 4 /* aligned for output (includes NOP padding) */
290 #else
291 #define LWIP_TCP_OPT_LEN_WS_OUT 0
292 #endif
293  
294 #if LWIP_TCP_SACK_OUT
295 #define LWIP_TCP_OPT_LEN_SACK_PERM 2
296 #define LWIP_TCP_OPT_LEN_SACK_PERM_OUT 4 /* aligned for output (includes NOP padding) */
297 #else
298 #define LWIP_TCP_OPT_LEN_SACK_PERM_OUT 0
299 #endif
300  
301 #define LWIP_TCP_OPT_LENGTH(flags) \
302 (flags & TF_SEG_OPTS_MSS ? LWIP_TCP_OPT_LEN_MSS : 0) + \
303 (flags & TF_SEG_OPTS_TS ? LWIP_TCP_OPT_LEN_TS_OUT : 0) + \
304 (flags & TF_SEG_OPTS_WND_SCALE ? LWIP_TCP_OPT_LEN_WS_OUT : 0) + \
305 (flags & TF_SEG_OPTS_SACK_PERM ? LWIP_TCP_OPT_LEN_SACK_PERM_OUT : 0)
306  
307 /** This returns a TCP header option for MSS in an u32_t */
308 #define TCP_BUILD_MSS_OPTION(mss) lwip_htonl(0x02040000 | ((mss) & 0xFFFF))
309  
310 #if LWIP_WND_SCALE
311 #define TCPWNDSIZE_F U32_F
312 #define TCPWND_MAX 0xFFFFFFFFU
313 #define TCPWND_CHECK16(x) LWIP_ASSERT("window size > 0xFFFF", (x) <= 0xFFFF)
314 #define TCPWND_MIN16(x) ((u16_t)LWIP_MIN((x), 0xFFFF))
315 #else /* LWIP_WND_SCALE */
316 #define TCPWNDSIZE_F U16_F
317 #define TCPWND_MAX 0xFFFFU
318 #define TCPWND_CHECK16(x)
319 #define TCPWND_MIN16(x) x
320 #endif /* LWIP_WND_SCALE */
321  
322 /* Global variables: */
323 extern struct tcp_pcb *tcp_input_pcb;
324 extern u32_t tcp_ticks;
325 extern u8_t tcp_active_pcbs_changed;
326  
327 /* The TCP PCB lists. */
328 union tcp_listen_pcbs_t { /* List of all TCP PCBs in LISTEN state. */
329 struct tcp_pcb_listen *listen_pcbs;
330 struct tcp_pcb *pcbs;
331 };
332 extern struct tcp_pcb *tcp_bound_pcbs;
333 extern union tcp_listen_pcbs_t tcp_listen_pcbs;
334 extern struct tcp_pcb *tcp_active_pcbs; /* List of all TCP PCBs that are in a
335 state in which they accept or send
336 data. */
337 extern struct tcp_pcb *tcp_tw_pcbs; /* List of all TCP PCBs in TIME-WAIT. */
338  
339 #define NUM_TCP_PCB_LISTS_NO_TIME_WAIT 3
340 #define NUM_TCP_PCB_LISTS 4
341 extern struct tcp_pcb ** const tcp_pcb_lists[NUM_TCP_PCB_LISTS];
342  
343 /* Axioms about the above lists:
344 1) Every TCP PCB that is not CLOSED is in one of the lists.
345 2) A PCB is only in one of the lists.
346 3) All PCBs in the tcp_listen_pcbs list is in LISTEN state.
347 4) All PCBs in the tcp_tw_pcbs list is in TIME-WAIT state.
348 */
349 /* Define two macros, TCP_REG and TCP_RMV that registers a TCP PCB
350 with a PCB list or removes a PCB from a list, respectively. */
351 #ifndef TCP_DEBUG_PCB_LISTS
352 #define TCP_DEBUG_PCB_LISTS 0
353 #endif
354 #if TCP_DEBUG_PCB_LISTS
355 #define TCP_REG(pcbs, npcb) do {\
356 struct tcp_pcb *tcp_tmp_pcb; \
357 LWIP_DEBUGF(TCP_DEBUG, ("TCP_REG %p local port %d\n", (npcb), (npcb)->local_port)); \
358 for (tcp_tmp_pcb = *(pcbs); \
359 tcp_tmp_pcb != NULL; \
360 tcp_tmp_pcb = tcp_tmp_pcb->next) { \
361 LWIP_ASSERT("TCP_REG: already registered\n", tcp_tmp_pcb != (npcb)); \
362 } \
363 LWIP_ASSERT("TCP_REG: pcb->state != CLOSED", ((pcbs) == &tcp_bound_pcbs) || ((npcb)->state != CLOSED)); \
364 (npcb)->next = *(pcbs); \
365 LWIP_ASSERT("TCP_REG: npcb->next != npcb", (npcb)->next != (npcb)); \
366 *(pcbs) = (npcb); \
367 LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
368 tcp_timer_needed(); \
369 } while(0)
370 #define TCP_RMV(pcbs, npcb) do { \
371 struct tcp_pcb *tcp_tmp_pcb; \
372 LWIP_ASSERT("TCP_RMV: pcbs != NULL", *(pcbs) != NULL); \
373 LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removing %p from %p\n", (npcb), *(pcbs))); \
374 if(*(pcbs) == (npcb)) { \
375 *(pcbs) = (*pcbs)->next; \
376 } else for (tcp_tmp_pcb = *(pcbs); tcp_tmp_pcb != NULL; tcp_tmp_pcb = tcp_tmp_pcb->next) { \
377 if(tcp_tmp_pcb->next == (npcb)) { \
378 tcp_tmp_pcb->next = (npcb)->next; \
379 break; \
380 } \
381 } \
382 (npcb)->next = NULL; \
383 LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
384 LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removed %p from %p\n", (npcb), *(pcbs))); \
385 } while(0)
386  
387 #else /* LWIP_DEBUG */
388  
389 #define TCP_REG(pcbs, npcb) \
390 do { \
391 (npcb)->next = *pcbs; \
392 *(pcbs) = (npcb); \
393 tcp_timer_needed(); \
394 } while (0)
395  
396 #define TCP_RMV(pcbs, npcb) \
397 do { \
398 if(*(pcbs) == (npcb)) { \
399 (*(pcbs)) = (*pcbs)->next; \
400 } \
401 else { \
402 struct tcp_pcb *tcp_tmp_pcb; \
403 for (tcp_tmp_pcb = *pcbs; \
404 tcp_tmp_pcb != NULL; \
405 tcp_tmp_pcb = tcp_tmp_pcb->next) { \
406 if(tcp_tmp_pcb->next == (npcb)) { \
407 tcp_tmp_pcb->next = (npcb)->next; \
408 break; \
409 } \
410 } \
411 } \
412 (npcb)->next = NULL; \
413 } while(0)
414  
415 #endif /* LWIP_DEBUG */
416  
417 #define TCP_REG_ACTIVE(npcb) \
418 do { \
419 TCP_REG(&tcp_active_pcbs, npcb); \
420 tcp_active_pcbs_changed = 1; \
421 } while (0)
422  
423 #define TCP_RMV_ACTIVE(npcb) \
424 do { \
425 TCP_RMV(&tcp_active_pcbs, npcb); \
426 tcp_active_pcbs_changed = 1; \
427 } while (0)
428  
429 #define TCP_PCB_REMOVE_ACTIVE(pcb) \
430 do { \
431 tcp_pcb_remove(&tcp_active_pcbs, pcb); \
432 tcp_active_pcbs_changed = 1; \
433 } while (0)
434  
435  
436 /* Internal functions: */
437 struct tcp_pcb *tcp_pcb_copy(struct tcp_pcb *pcb);
438 void tcp_pcb_purge(struct tcp_pcb *pcb);
439 void tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb);
440  
441 void tcp_segs_free(struct tcp_seg *seg);
442 void tcp_seg_free(struct tcp_seg *seg);
443 struct tcp_seg *tcp_seg_copy(struct tcp_seg *seg);
444  
445 #define tcp_ack(pcb) \
446 do { \
447 if((pcb)->flags & TF_ACK_DELAY) { \
448 tcp_clear_flags(pcb, TF_ACK_DELAY); \
449 tcp_ack_now(pcb); \
450 } \
451 else { \
452 tcp_set_flags(pcb, TF_ACK_DELAY); \
453 } \
454 } while (0)
455  
456 #define tcp_ack_now(pcb) \
457 tcp_set_flags(pcb, TF_ACK_NOW)
458  
459 err_t tcp_send_fin(struct tcp_pcb *pcb);
460 err_t tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags);
461  
462 void tcp_rexmit_seg(struct tcp_pcb *pcb, struct tcp_seg *seg);
463  
464 void tcp_rst(const struct tcp_pcb* pcb, u32_t seqno, u32_t ackno,
465 const ip_addr_t *local_ip, const ip_addr_t *remote_ip,
466 u16_t local_port, u16_t remote_port);
467  
468 u32_t tcp_next_iss(struct tcp_pcb *pcb);
469  
470 err_t tcp_keepalive(struct tcp_pcb *pcb);
471 err_t tcp_split_unsent_seg(struct tcp_pcb *pcb, u16_t split);
472 err_t tcp_zero_window_probe(struct tcp_pcb *pcb);
473 void tcp_trigger_input_pcb_close(void);
474  
475 #if TCP_CALCULATE_EFF_SEND_MSS
476 u16_t tcp_eff_send_mss_netif(u16_t sendmss, struct netif *outif,
477 const ip_addr_t *dest);
478 #define tcp_eff_send_mss(sendmss, src, dest) \
479 tcp_eff_send_mss_netif(sendmss, ip_route(src, dest), dest)
480 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
481  
482 #if LWIP_CALLBACK_API
483 err_t tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
484 #endif /* LWIP_CALLBACK_API */
485  
486 #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG
487 void tcp_debug_print(struct tcp_hdr *tcphdr);
488 void tcp_debug_print_flags(u8_t flags);
489 void tcp_debug_print_state(enum tcp_state s);
490 void tcp_debug_print_pcbs(void);
491 s16_t tcp_pcbs_sane(void);
492 #else
493 # define tcp_debug_print(tcphdr)
494 # define tcp_debug_print_flags(flags)
495 # define tcp_debug_print_state(s)
496 # define tcp_debug_print_pcbs()
497 # define tcp_pcbs_sane() 1
498 #endif /* TCP_DEBUG */
499  
500 /** External function (implemented in timers.c), called when TCP detects
501 * that a timer is needed (i.e. active- or time-wait-pcb found). */
502 void tcp_timer_needed(void);
503  
504 void tcp_netif_ip_addr_changed(const ip_addr_t* old_addr, const ip_addr_t* new_addr);
505  
506 #if TCP_QUEUE_OOSEQ
507 void tcp_free_ooseq(struct tcp_pcb *pcb);
508 #endif
509  
510 #ifdef __cplusplus
511 }
512 #endif
513  
514 #endif /* LWIP_TCP */
515  
516 #endif /* LWIP_HDR_TCP_PRIV_H */