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tcp.h
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1 /**
2  * @file
3  * TCP API (to be used from TCPIP thread)\n
4  * See also @ref tcp_raw
5  */
6 
7 /*
8  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without modification,
12  * are permitted provided that the following conditions are met:
13  *
14  * 1. Redistributions of source code must retain the above copyright notice,
15  * this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright notice,
17  * this list of conditions and the following disclaimer in the documentation
18  * and/or other materials provided with the distribution.
19  * 3. The name of the author may not be used to endorse or promote products
20  * derived from this software without specific prior written permission.
21  *
22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
23  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
24  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
25  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
26  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
27  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
31  * OF SUCH DAMAGE.
32  *
33  * This file is part of the lwIP TCP/IP stack.
34  *
35  * Author: Adam Dunkels <adam@sics.se>
36  *
37  */
38 #ifndef LWIP_HDR_TCP_H
39 #define LWIP_HDR_TCP_H
40 
41 #include "lwip/opt.h"
42 
43 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
44 
45 #include "lwip/tcpbase.h"
46 #include "lwip/mem.h"
47 #include "lwip/pbuf.h"
48 #include "lwip/ip.h"
49 #include "lwip/icmp.h"
50 #include "lwip/err.h"
51 #include "lwip/ip6.h"
52 #include "lwip/ip6_addr.h"
53 
54 #ifdef __cplusplus
55 extern "C" {
56 #endif
57 
58 struct tcp_pcb;
59 struct tcp_pcb_listen;
60 
61 /** Function prototype for tcp accept callback functions. Called when a new
62  * connection can be accepted on a listening pcb.
63  *
64  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
65  * @param newpcb The new connection pcb
66  * @param err An error code if there has been an error accepting.
67  * Only return ERR_ABRT if you have called tcp_abort from within the
68  * callback function!
69  */
70 typedef err_t (*tcp_accept_fn)(void *arg, struct tcp_pcb *newpcb, err_t err);
71 
72 /** Function prototype for tcp receive callback functions. Called when data has
73  * been received.
74  *
75  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
76  * @param tpcb The connection pcb which received data
77  * @param p The received data (or NULL when the connection has been closed!)
78  * @param err An error code if there has been an error receiving
79  * Only return ERR_ABRT if you have called tcp_abort from within the
80  * callback function!
81  */
82 typedef err_t (*tcp_recv_fn)(void *arg, struct tcp_pcb *tpcb,
83  struct pbuf *p, err_t err);
84 
85 /** Function prototype for tcp sent callback functions. Called when sent data has
86  * been acknowledged by the remote side. Use it to free corresponding resources.
87  * This also means that the pcb has now space available to send new data.
88  *
89  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
90  * @param tpcb The connection pcb for which data has been acknowledged
91  * @param len The amount of bytes acknowledged
92  * @return ERR_OK: try to send some data by calling tcp_output
93  * Only return ERR_ABRT if you have called tcp_abort from within the
94  * callback function!
95  */
96 typedef err_t (*tcp_sent_fn)(void *arg, struct tcp_pcb *tpcb,
97  u16_t len);
98 
99 /** Function prototype for tcp poll callback functions. Called periodically as
100  * specified by @see tcp_poll.
101  *
102  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
103  * @param tpcb tcp pcb
104  * @return ERR_OK: try to send some data by calling tcp_output
105  * Only return ERR_ABRT if you have called tcp_abort from within the
106  * callback function!
107  */
108 typedef err_t (*tcp_poll_fn)(void *arg, struct tcp_pcb *tpcb);
109 
110 /** Function prototype for tcp error callback functions. Called when the pcb
111  * receives a RST or is unexpectedly closed for any other reason.
112  *
113  * @note The corresponding pcb is already freed when this callback is called!
114  *
115  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
116  * @param err Error code to indicate why the pcb has been closed
117  * ERR_ABRT: aborted through tcp_abort or by a TCP timer
118  * ERR_RST: the connection was reset by the remote host
119  */
120 typedef void (*tcp_err_fn)(void *arg, err_t err);
121 
122 /** Function prototype for tcp connected callback functions. Called when a pcb
123  * is connected to the remote side after initiating a connection attempt by
124  * calling tcp_connect().
125  *
126  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
127  * @param tpcb The connection pcb which is connected
128  * @param err An unused error code, always ERR_OK currently ;-) @todo!
129  * Only return ERR_ABRT if you have called tcp_abort from within the
130  * callback function!
131  *
132  * @note When a connection attempt fails, the error callback is currently called!
133  */
134 typedef err_t (*tcp_connected_fn)(void *arg, struct tcp_pcb *tpcb, err_t err);
135 
136 #if LWIP_WND_SCALE
137 #define RCV_WND_SCALE(pcb, wnd) (((wnd) >> (pcb)->rcv_scale))
138 #define SND_WND_SCALE(pcb, wnd) (((wnd) << (pcb)->snd_scale))
139 #define TCPWND16(x) ((u16_t)LWIP_MIN((x), 0xFFFF))
140 #define TCP_WND_MAX(pcb) ((tcpwnd_size_t)(((pcb)->flags & TF_WND_SCALE) ? TCP_WND : TCPWND16(TCP_WND)))
141 #else
142 #define RCV_WND_SCALE(pcb, wnd) (wnd)
143 #define SND_WND_SCALE(pcb, wnd) (wnd)
144 #define TCPWND16(x) (x)
145 #define TCP_WND_MAX(pcb) TCP_WND
146 #endif
147 /* Increments a tcpwnd_size_t and holds at max value rather than rollover */
148 #define TCP_WND_INC(wnd, inc) do { \
149  if ((tcpwnd_size_t)(wnd + inc) >= wnd) { \
150  wnd = (tcpwnd_size_t)(wnd + inc); \
151  } else { \
152  wnd = (tcpwnd_size_t)-1; \
153  } \
154  } while(0)
155 
156 #if LWIP_TCP_SACK_OUT
157 /** SACK ranges to include in ACK packets.
158  * SACK entry is invalid if left==right. */
159 struct tcp_sack_range {
160  /** Left edge of the SACK: the first acknowledged sequence number. */
161  u32_t left;
162  /** Right edge of the SACK: the last acknowledged sequence number +1 (so first NOT acknowledged). */
163  u32_t right;
164 };
165 #endif /* LWIP_TCP_SACK_OUT */
166 
167 /** Function prototype for deallocation of arguments. Called *just before* the
168  * pcb is freed, so don't expect to be able to do anything with this pcb!
169  *
170  * @param id ext arg id (allocated via @ref tcp_ext_arg_alloc_id)
171  * @param data pointer to the data (set via @ref tcp_ext_arg_set before)
172  */
173 typedef void (*tcp_extarg_callback_pcb_destroyed_fn)(u8_t id, void *data);
174 
175 /** Function prototype to transition arguments from a listening pcb to an accepted pcb
176  *
177  * @param id ext arg id (allocated via @ref tcp_ext_arg_alloc_id)
178  * @param lpcb the listening pcb accepting a connection
179  * @param cpcb the newly allocated connection pcb
180  * @return ERR_OK if OK, any error if connection should be dropped
181  */
182 typedef err_t (*tcp_extarg_callback_passive_open_fn)(u8_t id, struct tcp_pcb_listen *lpcb, struct tcp_pcb *cpcb);
183 
184 /** A table of callback functions that is invoked for ext arguments */
185 struct tcp_ext_arg_callbacks {
186  /** @ref tcp_extarg_callback_pcb_destroyed_fn */
187  tcp_extarg_callback_pcb_destroyed_fn destroy;
188  /** @ref tcp_extarg_callback_passive_open_fn */
189  tcp_extarg_callback_passive_open_fn passive_open;
190 };
191 
192 #define LWIP_TCP_PCB_NUM_EXT_ARG_ID_INVALID 0xFF
193 
194 #if LWIP_TCP_PCB_NUM_EXT_ARGS
195 /* This is the structure for ext args in tcp pcbs (used as array) */
196 struct tcp_pcb_ext_args {
197  const struct tcp_ext_arg_callbacks *callbacks;
198  void *data;
199 };
200 /* This is a helper define to prevent zero size arrays if disabled */
201 #define TCP_PCB_EXTARGS struct tcp_pcb_ext_args ext_args[LWIP_TCP_PCB_NUM_EXT_ARGS];
202 #else
203 #define TCP_PCB_EXTARGS
204 #endif
205 
206 typedef u16_t tcpflags_t;
207 #define TCP_ALLFLAGS 0xffffU
208 
209 /**
210  * members common to struct tcp_pcb and struct tcp_listen_pcb
211  */
212 #define TCP_PCB_COMMON(type) \
213  type *next; /* for the linked list */ \
214  void *callback_arg; \
215  TCP_PCB_EXTARGS \
216  enum tcp_state state; /* TCP state */ \
217  u8_t prio; \
218  /* ports are in host byte order */ \
219  u16_t local_port
220 
221 
222 /** the TCP protocol control block for listening pcbs */
223 struct tcp_pcb_listen {
224 /** Common members of all PCB types */
225  IP_PCB;
226 /** Protocol specific PCB members */
227  TCP_PCB_COMMON(struct tcp_pcb_listen);
228 
229 #if LWIP_CALLBACK_API
230  /* Function to call when a listener has been connected. */
231  tcp_accept_fn accept;
232 #endif /* LWIP_CALLBACK_API */
233 
234 #if TCP_LISTEN_BACKLOG
235  u8_t backlog;
236  u8_t accepts_pending;
237 #endif /* TCP_LISTEN_BACKLOG */
238 };
239 
240 
241 /** the TCP protocol control block */
242 struct tcp_pcb {
243 /** common PCB members */
244  IP_PCB;
245 /** protocol specific PCB members */
246  TCP_PCB_COMMON(struct tcp_pcb);
247 
248  /* ports are in host byte order */
249  u16_t remote_port;
250 
251  tcpflags_t flags;
252 #define TF_ACK_DELAY 0x01U /* Delayed ACK. */
253 #define TF_ACK_NOW 0x02U /* Immediate ACK. */
254 #define TF_INFR 0x04U /* In fast recovery. */
255 #define TF_CLOSEPEND 0x08U /* If this is set, tcp_close failed to enqueue the FIN (retried in tcp_tmr) */
256 #define TF_RXCLOSED 0x10U /* rx closed by tcp_shutdown */
257 #define TF_FIN 0x20U /* Connection was closed locally (FIN segment enqueued). */
258 #define TF_NODELAY 0x40U /* Disable Nagle algorithm */
259 #define TF_NAGLEMEMERR 0x80U /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
260 #if LWIP_WND_SCALE
261 #define TF_WND_SCALE 0x0100U /* Window Scale option enabled */
262 #endif
263 #if TCP_LISTEN_BACKLOG
264 #define TF_BACKLOGPEND 0x0200U /* If this is set, a connection pcb has increased the backlog on its listener */
265 #endif
266 #if LWIP_TCP_TIMESTAMPS
267 #define TF_TIMESTAMP 0x0400U /* Timestamp option enabled */
268 #endif
269 #define TF_RTO 0x0800U /* RTO timer has fired, in-flight data moved to unsent and being retransmitted */
270 #if LWIP_TCP_SACK_OUT
271 #define TF_SACK 0x1000U /* Selective ACKs enabled */
272 #endif
273 
274  /* the rest of the fields are in host byte order
275  as we have to do some math with them */
276 
277  /* Timers */
278  u8_t polltmr, pollinterval;
279  u8_t last_timer;
280  u32_t tmr;
281 
282  /* receiver variables */
283  u32_t rcv_nxt; /* next seqno expected */
284  tcpwnd_size_t rcv_wnd; /* receiver window available */
285  tcpwnd_size_t rcv_ann_wnd; /* receiver window to announce */
286  u32_t rcv_ann_right_edge; /* announced right edge of window */
287 
288 #if LWIP_TCP_SACK_OUT
289  /* SACK ranges to include in ACK packets (entry is invalid if left==right) */
290  struct tcp_sack_range rcv_sacks[LWIP_TCP_MAX_SACK_NUM];
291 #define LWIP_TCP_SACK_VALID(pcb, idx) ((pcb)->rcv_sacks[idx].left != (pcb)->rcv_sacks[idx].right)
292 #endif /* LWIP_TCP_SACK_OUT */
293 
294  /* Retransmission timer. */
295  s16_t rtime;
296 
297  u16_t mss; /* maximum segment size */
298 
299  /* RTT (round trip time) estimation variables */
300  u32_t rttest; /* RTT estimate in 500ms ticks */
301  u32_t rtseq; /* sequence number being timed */
302  s16_t sa, sv; /* @see "Congestion Avoidance and Control" by Van Jacobson and Karels */
303 
304  s16_t rto; /* retransmission time-out (in ticks of TCP_SLOW_INTERVAL) */
305  u8_t nrtx; /* number of retransmissions */
306 
307  /* fast retransmit/recovery */
308  u8_t dupacks;
309  u32_t lastack; /* Highest acknowledged seqno. */
310 
311  /* congestion avoidance/control variables */
312  tcpwnd_size_t cwnd;
313  tcpwnd_size_t ssthresh;
314 
315  /* first byte following last rto byte */
316  u32_t rto_end;
317 
318  /* sender variables */
319  u32_t snd_nxt; /* next new seqno to be sent */
320  u32_t snd_wl1, snd_wl2; /* Sequence and acknowledgement numbers of last
321  window update. */
322  u32_t snd_lbb; /* Sequence number of next byte to be buffered. */
323  tcpwnd_size_t snd_wnd; /* sender window */
324  tcpwnd_size_t snd_wnd_max; /* the maximum sender window announced by the remote host */
325 
326  tcpwnd_size_t snd_buf; /* Available buffer space for sending (in bytes). */
327 #define TCP_SNDQUEUELEN_OVERFLOW (0xffffU-3)
328  u16_t snd_queuelen; /* Number of pbufs currently in the send buffer. */
329 
330 #if TCP_OVERSIZE
331  /* Extra bytes available at the end of the last pbuf in unsent. */
332  u16_t unsent_oversize;
333 #endif /* TCP_OVERSIZE */
334 
335  tcpwnd_size_t bytes_acked;
336 
337  /* These are ordered by sequence number: */
338  struct tcp_seg *unsent; /* Unsent (queued) segments. */
339  struct tcp_seg *unacked; /* Sent but unacknowledged segments. */
340 #if TCP_QUEUE_OOSEQ
341  struct tcp_seg *ooseq; /* Received out of sequence segments. */
342 #endif /* TCP_QUEUE_OOSEQ */
343 
344  struct pbuf *refused_data; /* Data previously received but not yet taken by upper layer */
345 
346 #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
347  struct tcp_pcb_listen* listener;
348 #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
349 
350 #if LWIP_CALLBACK_API
351  /* Function to be called when more send buffer space is available. */
352  tcp_sent_fn sent;
353  /* Function to be called when (in-sequence) data has arrived. */
354  tcp_recv_fn recv;
355  /* Function to be called when a connection has been set up. */
356  tcp_connected_fn connected;
357  /* Function which is called periodically. */
358  tcp_poll_fn poll;
359  /* Function to be called whenever a fatal error occurs. */
360  tcp_err_fn errf;
361 #endif /* LWIP_CALLBACK_API */
362 
363 #if LWIP_TCP_TIMESTAMPS
364  u32_t ts_lastacksent;
365  u32_t ts_recent;
366 #endif /* LWIP_TCP_TIMESTAMPS */
367 
368  /* idle time before KEEPALIVE is sent */
369  u32_t keep_idle;
370 #if LWIP_TCP_KEEPALIVE
371  u32_t keep_intvl;
372  u32_t keep_cnt;
373 #endif /* LWIP_TCP_KEEPALIVE */
374 
375  /* Persist timer counter */
376  u8_t persist_cnt;
377  /* Persist timer back-off */
378  u8_t persist_backoff;
379  /* Number of persist probes */
380  u8_t persist_probe;
381 
382  /* KEEPALIVE counter */
383  u8_t keep_cnt_sent;
384 
385 #if LWIP_WND_SCALE
386  u8_t snd_scale;
387  u8_t rcv_scale;
388 #endif
389 };
390 
391 #if LWIP_EVENT_API
392 
393 enum lwip_event {
394  LWIP_EVENT_ACCEPT,
395  LWIP_EVENT_SENT,
396  LWIP_EVENT_RECV,
397  LWIP_EVENT_CONNECTED,
398  LWIP_EVENT_POLL,
399  LWIP_EVENT_ERR
400 };
401 
402 err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
403  enum lwip_event,
404  struct pbuf *p,
405  u16_t size,
406  err_t err);
407 
408 #endif /* LWIP_EVENT_API */
409 
410 /* Application program's interface: */
411 struct tcp_pcb * tcp_new (void);
412 struct tcp_pcb * tcp_new_ip_type (u8_t type);
413 
414 void tcp_arg (struct tcp_pcb *pcb, void *arg);
415 #if LWIP_CALLBACK_API
416 void tcp_recv (struct tcp_pcb *pcb, tcp_recv_fn recv);
417 void tcp_sent (struct tcp_pcb *pcb, tcp_sent_fn sent);
418 void tcp_err (struct tcp_pcb *pcb, tcp_err_fn err);
419 void tcp_accept (struct tcp_pcb *pcb, tcp_accept_fn accept);
420 #endif /* LWIP_CALLBACK_API */
421 void tcp_poll (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
422 
423 #define tcp_set_flags(pcb, set_flags) do { (pcb)->flags = (tcpflags_t)((pcb)->flags | (set_flags)); } while(0)
424 #define tcp_clear_flags(pcb, clr_flags) do { (pcb)->flags = (tcpflags_t)((pcb)->flags & (tcpflags_t)(~(clr_flags) & TCP_ALLFLAGS)); } while(0)
425 #define tcp_is_flag_set(pcb, flag) (((pcb)->flags & (flag)) != 0)
426 
427 #if LWIP_TCP_TIMESTAMPS
428 #define tcp_mss(pcb) (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12) : (pcb)->mss)
429 #else /* LWIP_TCP_TIMESTAMPS */
430 /** @ingroup tcp_raw */
431 #define tcp_mss(pcb) ((pcb)->mss)
432 #endif /* LWIP_TCP_TIMESTAMPS */
433 /** @ingroup tcp_raw */
434 #define tcp_sndbuf(pcb) (TCPWND16((pcb)->snd_buf))
435 /** @ingroup tcp_raw */
436 #define tcp_sndqueuelen(pcb) ((pcb)->snd_queuelen)
437 /** @ingroup tcp_raw */
438 #define tcp_nagle_disable(pcb) tcp_set_flags(pcb, TF_NODELAY)
439 /** @ingroup tcp_raw */
440 #define tcp_nagle_enable(pcb) tcp_clear_flags(pcb, TF_NODELAY)
441 /** @ingroup tcp_raw */
442 #define tcp_nagle_disabled(pcb) tcp_is_flag_set(pcb, TF_NODELAY)
443 
444 #if TCP_LISTEN_BACKLOG
445 #define tcp_backlog_set(pcb, new_backlog) do { \
446  LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", (pcb)->state == LISTEN); \
447  ((struct tcp_pcb_listen *)(pcb))->backlog = ((new_backlog) ? (new_backlog) : 1); } while(0)
448 void tcp_backlog_delayed(struct tcp_pcb* pcb);
449 void tcp_backlog_accepted(struct tcp_pcb* pcb);
450 #else /* TCP_LISTEN_BACKLOG */
451 #define tcp_backlog_set(pcb, new_backlog)
452 #define tcp_backlog_delayed(pcb)
453 #define tcp_backlog_accepted(pcb)
454 #endif /* TCP_LISTEN_BACKLOG */
455 #define tcp_accepted(pcb) do { LWIP_UNUSED_ARG(pcb); } while(0) /* compatibility define, not needed any more */
456 
457 void tcp_recved (struct tcp_pcb *pcb, u16_t len);
458 err_t tcp_bind (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
459  u16_t port);
460 void tcp_bind_netif(struct tcp_pcb *pcb, const struct netif *netif);
461 err_t tcp_connect (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
462  u16_t port, tcp_connected_fn connected);
463 
464 struct tcp_pcb * tcp_listen_with_backlog_and_err(struct tcp_pcb *pcb, u8_t backlog, err_t *err);
465 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
466 /** @ingroup tcp_raw */
467 #define tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
468 
469 void tcp_abort (struct tcp_pcb *pcb);
470 err_t tcp_close (struct tcp_pcb *pcb);
471 err_t tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx);
472 
473 err_t tcp_write (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
474  u8_t apiflags);
475 
476 void tcp_setprio (struct tcp_pcb *pcb, u8_t prio);
477 
478 err_t tcp_output (struct tcp_pcb *pcb);
479 
480 err_t tcp_tcp_get_tcp_addrinfo(struct tcp_pcb *pcb, int local, ip_addr_t *addr, u16_t *port);
481 
482 #define tcp_dbg_get_tcp_state(pcb) ((pcb)->state)
483 
484 /* for compatibility with older implementation */
485 #define tcp_new_ip6() tcp_new_ip_type(IPADDR_TYPE_V6)
486 
487 #if LWIP_TCP_PCB_NUM_EXT_ARGS
488 u8_t tcp_ext_arg_alloc_id(void);
489 void tcp_ext_arg_set_callbacks(struct tcp_pcb *pcb, uint8_t id, const struct tcp_ext_arg_callbacks * const callbacks);
490 void tcp_ext_arg_set(struct tcp_pcb *pcb, uint8_t id, void *arg);
491 void *tcp_ext_arg_get(const struct tcp_pcb *pcb, uint8_t id);
492 #endif
493 
494 #ifdef __cplusplus
495 }
496 #endif
497 
498 #endif /* LWIP_TCP */
499 
500 #endif /* LWIP_HDR_TCP_H */
Heap API.
IPv6 layer.
int poll(pollfh fhs[], unsigned nfhs, int timeout)
A mechanism to multiplex input/output over a set of file handles(file descriptors).
IP API.
#define IP_PCB
This is the common part of all PCB types.
Definition: ip.h:76
lwIP Options Configuration
IPv6 addresses.
Main packet buffer struct.
lwIP Error codes
Generic data structure used for all lwIP network interfaces.
s8_t err_t
Define LWIP_ERR_T in cc.h if you want to use a different type for your platform (must be signed)...
Definition: err.h:96
pbuf API
IP address structure for passing IP addresses by value.
Definition: nsapi_types.h:235
ICMP API.
#define LWIP_TCP_MAX_SACK_NUM
LWIP_TCP_MAX_SACK_NUM: The maximum number of SACK values to include in TCP segments.
Definition: opt.h:1282
Base TCP API definitions shared by TCP and ALTCP See also tcp_raw.
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