[TCPIP]
[reactos.git] / reactos / lib / drivers / lwip / src / include / lwip / tcp_impl.h
1 /*
2 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without modification,
6 * are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice,
9 * this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation
12 * and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
19 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
21 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
24 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
25 * OF SUCH DAMAGE.
26 *
27 * This file is part of the lwIP TCP/IP stack.
28 *
29 * Author: Adam Dunkels <adam@sics.se>
30 *
31 */
32 #ifndef __LWIP_TCP_IMPL_H__
33 #define __LWIP_TCP_IMPL_H__
34
35 #include "lwip/opt.h"
36
37 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
38
39 #include "lwip/tcp.h"
40 #include "lwip/sys.h"
41 #include "lwip/mem.h"
42 #include "lwip/pbuf.h"
43 #include "lwip/ip.h"
44 #include "lwip/icmp.h"
45 #include "lwip/err.h"
46
47 #ifdef __cplusplus
48 extern "C" {
49 #endif
50
51 /* Functions for interfacing with TCP: */
52
53 /* Lower layer interface to TCP: */
54 #define tcp_init() /* Compatibility define, no init needed. */
55 void tcp_tmr (void); /* Must be called every
56 TCP_TMR_INTERVAL
57 ms. (Typically 250 ms). */
58 /* It is also possible to call these two functions at the right
59 intervals (instead of calling tcp_tmr()). */
60 void tcp_slowtmr (void);
61 void tcp_fasttmr (void);
62
63
64 /* Only used by IP to pass a TCP segment to TCP: */
65 void tcp_input (struct pbuf *p, struct netif *inp);
66 /* Used within the TCP code only: */
67 struct tcp_pcb * tcp_alloc (u8_t prio);
68 void tcp_abandon (struct tcp_pcb *pcb, int reset);
69 err_t tcp_send_empty_ack(struct tcp_pcb *pcb);
70 void tcp_rexmit (struct tcp_pcb *pcb);
71 void tcp_rexmit_rto (struct tcp_pcb *pcb);
72 void tcp_rexmit_fast (struct tcp_pcb *pcb);
73 u32_t tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb);
74
75 /**
76 * This is the Nagle algorithm: try to combine user data to send as few TCP
77 * segments as possible. Only send if
78 * - no previously transmitted data on the connection remains unacknowledged or
79 * - the TF_NODELAY flag is set (nagle algorithm turned off for this pcb) or
80 * - the only unsent segment is at least pcb->mss bytes long (or there is more
81 * than one unsent segment - with lwIP, this can happen although unsent->len < mss)
82 * - or if we are in fast-retransmit (TF_INFR)
83 */
84 #define tcp_do_output_nagle(tpcb) ((((tpcb)->unacked == NULL) || \
85 ((tpcb)->flags & (TF_NODELAY | TF_INFR)) || \
86 (((tpcb)->unsent != NULL) && (((tpcb)->unsent->next != NULL) || \
87 ((tpcb)->unsent->len >= (tpcb)->mss))) \
88 ) ? 1 : 0)
89 #define tcp_output_nagle(tpcb) (tcp_do_output_nagle(tpcb) ? tcp_output(tpcb) : ERR_OK)
90
91
92 #define TCP_SEQ_LT(a,b) ((s32_t)((a)-(b)) < 0)
93 #define TCP_SEQ_LEQ(a,b) ((s32_t)((a)-(b)) <= 0)
94 #define TCP_SEQ_GT(a,b) ((s32_t)((a)-(b)) > 0)
95 #define TCP_SEQ_GEQ(a,b) ((s32_t)((a)-(b)) >= 0)
96 /* is b<=a<=c? */
97 #if 0 /* see bug #10548 */
98 #define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
99 #endif
100 #define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
101 #define TCP_FIN 0x01U
102 #define TCP_SYN 0x02U
103 #define TCP_RST 0x04U
104 #define TCP_PSH 0x08U
105 #define TCP_ACK 0x10U
106 #define TCP_URG 0x20U
107 #define TCP_ECE 0x40U
108 #define TCP_CWR 0x80U
109
110 #define TCP_FLAGS 0x3fU
111
112 /* Length of the TCP header, excluding options. */
113 #define TCP_HLEN 20
114
115 #ifndef TCP_TMR_INTERVAL
116 #define TCP_TMR_INTERVAL 250 /* The TCP timer interval in milliseconds. */
117 #endif /* TCP_TMR_INTERVAL */
118
119 #ifndef TCP_FAST_INTERVAL
120 #define TCP_FAST_INTERVAL TCP_TMR_INTERVAL /* the fine grained timeout in milliseconds */
121 #endif /* TCP_FAST_INTERVAL */
122
123 #ifndef TCP_SLOW_INTERVAL
124 #define TCP_SLOW_INTERVAL (2*TCP_TMR_INTERVAL) /* the coarse grained timeout in milliseconds */
125 #endif /* TCP_SLOW_INTERVAL */
126
127 #define TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */
128 #define TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */
129
130 #define TCP_OOSEQ_TIMEOUT 6U /* x RTO */
131
132 #ifndef TCP_MSL
133 #define TCP_MSL 60000UL /* The maximum segment lifetime in milliseconds */
134 #endif
135
136 /* Keepalive values, compliant with RFC 1122. Don't change this unless you know what you're doing */
137 #ifndef TCP_KEEPIDLE_DEFAULT
138 #define TCP_KEEPIDLE_DEFAULT 7200000UL /* Default KEEPALIVE timer in milliseconds */
139 #endif
140
141 #ifndef TCP_KEEPINTVL_DEFAULT
142 #define TCP_KEEPINTVL_DEFAULT 75000UL /* Default Time between KEEPALIVE probes in milliseconds */
143 #endif
144
145 #ifndef TCP_KEEPCNT_DEFAULT
146 #define TCP_KEEPCNT_DEFAULT 9U /* Default Counter for KEEPALIVE probes */
147 #endif
148
149 #define TCP_MAXIDLE TCP_KEEPCNT_DEFAULT * TCP_KEEPINTVL_DEFAULT /* Maximum KEEPALIVE probe time */
150
151 /* Fields are (of course) in network byte order.
152 * Some fields are converted to host byte order in tcp_input().
153 */
154 #ifdef PACK_STRUCT_USE_INCLUDES
155 # include "arch/bpstruct.h"
156 #endif
157 PACK_STRUCT_BEGIN
158 struct tcp_hdr {
159 PACK_STRUCT_FIELD(u16_t src);
160 PACK_STRUCT_FIELD(u16_t dest);
161 PACK_STRUCT_FIELD(u32_t seqno);
162 PACK_STRUCT_FIELD(u32_t ackno);
163 PACK_STRUCT_FIELD(u16_t _hdrlen_rsvd_flags);
164 PACK_STRUCT_FIELD(u16_t wnd);
165 PACK_STRUCT_FIELD(u16_t chksum);
166 PACK_STRUCT_FIELD(u16_t urgp);
167 } PACK_STRUCT_STRUCT;
168 PACK_STRUCT_END
169 #ifdef PACK_STRUCT_USE_INCLUDES
170 # include "arch/epstruct.h"
171 #endif
172
173 #define TCPH_OFFSET(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 8)
174 #define TCPH_HDRLEN(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 12)
175 #define TCPH_FLAGS(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)
176
177 #define TCPH_OFFSET_SET(phdr, offset) (phdr)->_hdrlen_rsvd_flags = htons(((offset) << 8) | TCPH_FLAGS(phdr))
178 #define TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | TCPH_FLAGS(phdr))
179 #define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(u16_t)(TCP_FLAGS)))) | htons(flags))
180 #define TCPH_HDRLEN_FLAGS_SET(phdr, len, flags) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | (flags))
181
182 #define TCPH_SET_FLAG(phdr, flags ) (phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags | htons(flags))
183 #define TCPH_UNSET_FLAG(phdr, flags) (phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) | (TCPH_FLAGS(phdr) & ~(flags)) )
184
185 #define TCP_TCPLEN(seg) ((seg)->len + ((TCPH_FLAGS((seg)->tcphdr) & (TCP_FIN | TCP_SYN)) != 0))
186
187 /** Flags used on input processing, not on pcb->flags
188 */
189 #define TF_RESET (u8_t)0x08U /* Connection was reset. */
190 #define TF_CLOSED (u8_t)0x10U /* Connection was sucessfully closed. */
191 #define TF_GOT_FIN (u8_t)0x20U /* Connection was closed by the remote end. */
192
193
194 #if LWIP_EVENT_API
195
196 #define TCP_EVENT_ACCEPT(pcb,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
197 LWIP_EVENT_ACCEPT, NULL, 0, err)
198 #define TCP_EVENT_SENT(pcb,space,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
199 LWIP_EVENT_SENT, NULL, space, ERR_OK)
200 #define TCP_EVENT_RECV(pcb,p,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
201 LWIP_EVENT_RECV, (p), 0, (err))
202 #define TCP_EVENT_CLOSED(pcb,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
203 LWIP_EVENT_RECV, NULL, 0, ERR_OK)
204 #define TCP_EVENT_CONNECTED(pcb,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
205 LWIP_EVENT_CONNECTED, NULL, 0, (err))
206 #define TCP_EVENT_POLL(pcb,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
207 LWIP_EVENT_POLL, NULL, 0, ERR_OK)
208 #define TCP_EVENT_ERR(errf,arg,err) lwip_tcp_event((arg), NULL, \
209 LWIP_EVENT_ERR, NULL, 0, (err))
210
211 #else /* LWIP_EVENT_API */
212
213 #define TCP_EVENT_ACCEPT(pcb,err,ret) \
214 do { \
215 if((pcb)->accept != NULL) \
216 (ret) = (pcb)->accept((pcb)->callback_arg,(pcb),(err)); \
217 else (ret) = ERR_ARG; \
218 } while (0)
219
220 #define TCP_EVENT_SENT(pcb,space,ret) \
221 do { \
222 if((pcb)->sent != NULL) \
223 (ret) = (pcb)->sent((pcb)->callback_arg,(pcb),(space)); \
224 else (ret) = ERR_OK; \
225 } while (0)
226
227 #define TCP_EVENT_RECV(pcb,p,err,ret) \
228 do { \
229 if((pcb)->recv != NULL) { \
230 (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err));\
231 } else { \
232 (ret) = tcp_recv_null(NULL, (pcb), (p), (err)); \
233 } \
234 } while (0)
235
236 #define TCP_EVENT_CLOSED(pcb,ret) \
237 do { \
238 if(((pcb)->recv != NULL)) { \
239 (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),NULL,ERR_OK);\
240 } else { \
241 (ret) = ERR_OK; \
242 } \
243 } while (0)
244
245 #define TCP_EVENT_CONNECTED(pcb,err,ret) \
246 do { \
247 if((pcb)->connected != NULL) \
248 (ret) = (pcb)->connected((pcb)->callback_arg,(pcb),(err)); \
249 else (ret) = ERR_OK; \
250 } while (0)
251
252 #define TCP_EVENT_POLL(pcb,ret) \
253 do { \
254 if((pcb)->poll != NULL) \
255 (ret) = (pcb)->poll((pcb)->callback_arg,(pcb)); \
256 else (ret) = ERR_OK; \
257 } while (0)
258
259 #define TCP_EVENT_ERR(errf,arg,err) \
260 do { \
261 if((errf) != NULL) \
262 (errf)((arg),(err)); \
263 } while (0)
264
265 #endif /* LWIP_EVENT_API */
266
267 /** Enabled extra-check for TCP_OVERSIZE if LWIP_DEBUG is enabled */
268 #if TCP_OVERSIZE && defined(LWIP_DEBUG)
269 #define TCP_OVERSIZE_DBGCHECK 1
270 #else
271 #define TCP_OVERSIZE_DBGCHECK 0
272 #endif
273
274 /** Don't generate checksum on copy if CHECKSUM_GEN_TCP is disabled */
275 #define TCP_CHECKSUM_ON_COPY (LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_TCP)
276
277 /* This structure represents a TCP segment on the unsent, unacked and ooseq queues */
278 struct tcp_seg {
279 struct tcp_seg *next; /* used when putting segements on a queue */
280 struct pbuf *p; /* buffer containing data + TCP header */
281 u16_t len; /* the TCP length of this segment */
282 #if TCP_OVERSIZE_DBGCHECK
283 u16_t oversize_left; /* Extra bytes available at the end of the last
284 pbuf in unsent (used for asserting vs.
285 tcp_pcb.unsent_oversized only) */
286 #endif /* TCP_OVERSIZE_DBGCHECK */
287 #if TCP_CHECKSUM_ON_COPY
288 u16_t chksum;
289 u8_t chksum_swapped;
290 #endif /* TCP_CHECKSUM_ON_COPY */
291 u8_t flags;
292 #define TF_SEG_OPTS_MSS (u8_t)0x01U /* Include MSS option. */
293 #define TF_SEG_OPTS_TS (u8_t)0x02U /* Include timestamp option. */
294 #define TF_SEG_DATA_CHECKSUMMED (u8_t)0x04U /* ALL data (not the header) is
295 checksummed into 'chksum' */
296 struct tcp_hdr *tcphdr; /* the TCP header */
297 };
298
299 #define LWIP_TCP_OPT_LENGTH(flags) \
300 (flags & TF_SEG_OPTS_MSS ? 4 : 0) + \
301 (flags & TF_SEG_OPTS_TS ? 12 : 0)
302
303 /** This returns a TCP header option for MSS in an u32_t */
304 #define TCP_BUILD_MSS_OPTION(x) (x) = PP_HTONL(((u32_t)2 << 24) | \
305 ((u32_t)4 << 16) | \
306 (((u32_t)TCP_MSS / 256) << 8) | \
307 (TCP_MSS & 255))
308
309 /* Global variables: */
310 extern struct tcp_pcb *tcp_input_pcb;
311 extern u32_t tcp_ticks;
312
313 /* The TCP PCB lists. */
314 union tcp_listen_pcbs_t { /* List of all TCP PCBs in LISTEN state. */
315 struct tcp_pcb_listen *listen_pcbs;
316 struct tcp_pcb *pcbs;
317 };
318 extern struct tcp_pcb *tcp_bound_pcbs;
319 extern union tcp_listen_pcbs_t tcp_listen_pcbs;
320 extern struct tcp_pcb *tcp_active_pcbs; /* List of all TCP PCBs that are in a
321 state in which they accept or send
322 data. */
323 extern struct tcp_pcb *tcp_tw_pcbs; /* List of all TCP PCBs in TIME-WAIT. */
324
325 extern struct tcp_pcb *tcp_tmp_pcb; /* Only used for temporary storage. */
326
327 /* Axioms about the above lists:
328 1) Every TCP PCB that is not CLOSED is in one of the lists.
329 2) A PCB is only in one of the lists.
330 3) All PCBs in the tcp_listen_pcbs list is in LISTEN state.
331 4) All PCBs in the tcp_tw_pcbs list is in TIME-WAIT state.
332 */
333 /* Define two macros, TCP_REG and TCP_RMV that registers a TCP PCB
334 with a PCB list or removes a PCB from a list, respectively. */
335 #ifndef TCP_DEBUG_PCB_LISTS
336 #define TCP_DEBUG_PCB_LISTS 0
337 #endif
338 #if TCP_DEBUG_PCB_LISTS
339 #define TCP_REG(pcbs, npcb) do {\
340 LWIP_DEBUGF(TCP_DEBUG, ("TCP_REG %p local port %d\n", (npcb), (npcb)->local_port)); \
341 for(tcp_tmp_pcb = *(pcbs); \
342 tcp_tmp_pcb != NULL; \
343 tcp_tmp_pcb = tcp_tmp_pcb->next) { \
344 LWIP_ASSERT("TCP_REG: already registered\n", tcp_tmp_pcb != (npcb)); \
345 } \
346 LWIP_ASSERT("TCP_REG: pcb->state != CLOSED", ((pcbs) == &tcp_bound_pcbs) || ((npcb)->state != CLOSED)); \
347 (npcb)->next = *(pcbs); \
348 LWIP_ASSERT("TCP_REG: npcb->next != npcb", (npcb)->next != (npcb)); \
349 *(pcbs) = (npcb); \
350 LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
351 tcp_timer_needed(); \
352 } while(0)
353 #define TCP_RMV(pcbs, npcb) do { \
354 LWIP_ASSERT("TCP_RMV: pcbs != NULL", *(pcbs) != NULL); \
355 LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removing %p from %p\n", (npcb), *(pcbs))); \
356 if(*(pcbs) == (npcb)) { \
357 *(pcbs) = (*pcbs)->next; \
358 } else for(tcp_tmp_pcb = *(pcbs); tcp_tmp_pcb != NULL; tcp_tmp_pcb = tcp_tmp_pcb->next) { \
359 if(tcp_tmp_pcb->next == (npcb)) { \
360 tcp_tmp_pcb->next = (npcb)->next; \
361 break; \
362 } \
363 } \
364 (npcb)->next = NULL; \
365 LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
366 LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removed %p from %p\n", (npcb), *(pcbs))); \
367 } while(0)
368
369 #else /* LWIP_DEBUG */
370
371 #define TCP_REG(pcbs, npcb) \
372 do { \
373 (npcb)->next = *pcbs; \
374 *(pcbs) = (npcb); \
375 tcp_timer_needed(); \
376 } while (0)
377
378 #define TCP_RMV(pcbs, npcb) \
379 do { \
380 if(*(pcbs) == (npcb)) { \
381 (*(pcbs)) = (*pcbs)->next; \
382 } \
383 else { \
384 for(tcp_tmp_pcb = *pcbs; \
385 tcp_tmp_pcb != NULL; \
386 tcp_tmp_pcb = tcp_tmp_pcb->next) { \
387 if(tcp_tmp_pcb->next == (npcb)) { \
388 tcp_tmp_pcb->next = (npcb)->next; \
389 break; \
390 } \
391 } \
392 } \
393 (npcb)->next = NULL; \
394 } while(0)
395
396 #endif /* LWIP_DEBUG */
397
398
399 /* Internal functions: */
400 struct tcp_pcb *tcp_pcb_copy(struct tcp_pcb *pcb);
401 void tcp_pcb_purge(struct tcp_pcb *pcb);
402 void tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb);
403
404 void tcp_segs_free(struct tcp_seg *seg);
405 void tcp_seg_free(struct tcp_seg *seg);
406 struct tcp_seg *tcp_seg_copy(struct tcp_seg *seg);
407
408 #define tcp_ack(pcb) \
409 do { \
410 if((pcb)->flags & TF_ACK_DELAY) { \
411 (pcb)->flags &= ~TF_ACK_DELAY; \
412 (pcb)->flags |= TF_ACK_NOW; \
413 } \
414 else { \
415 (pcb)->flags |= TF_ACK_DELAY; \
416 } \
417 } while (0)
418
419 #define tcp_ack_now(pcb) \
420 do { \
421 (pcb)->flags |= TF_ACK_NOW; \
422 } while (0)
423
424 err_t tcp_send_fin(struct tcp_pcb *pcb);
425 err_t tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags);
426
427 void tcp_rexmit_seg(struct tcp_pcb *pcb, struct tcp_seg *seg);
428
429 void tcp_rst(u32_t seqno, u32_t ackno,
430 ip_addr_t *local_ip, ip_addr_t *remote_ip,
431 u16_t local_port, u16_t remote_port);
432
433 u32_t tcp_next_iss(void);
434
435 void tcp_keepalive(struct tcp_pcb *pcb);
436 void tcp_zero_window_probe(struct tcp_pcb *pcb);
437
438 #if TCP_CALCULATE_EFF_SEND_MSS
439 u16_t tcp_eff_send_mss(u16_t sendmss, ip_addr_t *addr);
440 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
441
442 #if LWIP_CALLBACK_API
443 err_t tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
444 #endif /* LWIP_CALLBACK_API */
445
446 #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG
447 void tcp_debug_print(struct tcp_hdr *tcphdr);
448 void tcp_debug_print_flags(u8_t flags);
449 void tcp_debug_print_state(enum tcp_state s);
450 void tcp_debug_print_pcbs(void);
451 s16_t tcp_pcbs_sane(void);
452 #else
453 # define tcp_debug_print(tcphdr)
454 # define tcp_debug_print_flags(flags)
455 # define tcp_debug_print_state(s)
456 # define tcp_debug_print_pcbs()
457 # define tcp_pcbs_sane() 1
458 #endif /* TCP_DEBUG */
459
460 /** External function (implemented in timers.c), called when TCP detects
461 * that a timer is needed (i.e. active- or time-wait-pcb found). */
462 void tcp_timer_needed(void);
463
464
465 #ifdef __cplusplus
466 }
467 #endif
468
469 #endif /* LWIP_TCP */
470
471 #endif /* __LWIP_TCP_H__ */