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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_H__
33 #define __LWIP_TCP_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/sys.h"
40 #include "lwip/mem.h"
41 #include "lwip/pbuf.h"
42 #include "lwip/ip.h"
43 #include "lwip/icmp.h"
44 #include "lwip/err.h"
45 
46 #ifdef __cplusplus
47 extern "C" {
48 #endif
49 
50 struct tcp_pcb;
51 
52 /** Function prototype for tcp accept callback functions. Called when a new
53  * connection can be accepted on a listening pcb.
54  *
55  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
56  * @param newpcb The new connection pcb
57  * @param err An error code if there has been an error accepting.
58  *            Only return ERR_ABRT if you have called tcp_abort from within the
59  *            callback function!
60  */
61 typedef err_t (*tcp_accept_fn)(void *arg, struct tcp_pcb *newpcb, err_t err);
62 
63 /** Function prototype for tcp receive callback functions. Called when data has
64  * been received.
65  *
66  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
67  * @param tpcb The connection pcb which received data
68  * @param p The received data (or NULL when the connection has been closed!)
69  * @param err An error code if there has been an error receiving
70  *            Only return ERR_ABRT if you have called tcp_abort from within the
71  *            callback function!
72  */
73 typedef err_t (*tcp_recv_fn)(void *arg, struct tcp_pcb *tpcb,
74                              struct pbuf *p, err_t err);
75 
76 /** Function prototype for tcp sent callback functions. Called when sent data has
77  * been acknowledged by the remote side. Use it to free corresponding resources.
78  * This also means that the pcb has now space available to send new data.
79  *
80  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
81  * @param tpcb The connection pcb for which data has been acknowledged
82  * @param len The amount of bytes acknowledged
83  * @return ERR_OK: try to send some data by calling tcp_output
84  *            Only return ERR_ABRT if you have called tcp_abort from within the
85  *            callback function!
86  */
87 typedef err_t (*tcp_sent_fn)(void *arg, struct tcp_pcb *tpcb,
88                               u16_t len);
89 
90 /** Function prototype for tcp poll callback functions. Called periodically as
91  * specified by @see tcp_poll.
92  *
93  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
94  * @param tpcb tcp pcb
95  * @return ERR_OK: try to send some data by calling tcp_output
96  *            Only return ERR_ABRT if you have called tcp_abort from within the
97  *            callback function!
98  */
99 typedef err_t (*tcp_poll_fn)(void *arg, struct tcp_pcb *tpcb);
100 
101 /** Function prototype for tcp error callback functions. Called when the pcb
102  * receives a RST or is unexpectedly closed for any other reason.
103  *
104  * @note The corresponding pcb is already freed when this callback is called!
105  *
106  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
107  * @param err Error code to indicate why the pcb has been closed
108  *            ERR_ABRT: aborted through tcp_abort or by a TCP timer
109  *            ERR_RST: the connection was reset by the remote host
110  */
111 typedef void  (*tcp_err_fn)(void *arg, err_t err);
112 
113 /** Function prototype for tcp connected callback functions. Called when a pcb
114  * is connected to the remote side after initiating a connection attempt by
115  * calling tcp_connect().
116  *
117  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
118  * @param tpcb The connection pcb which is connected
119  * @param err An unused error code, always ERR_OK currently ;-) TODO!
120  *            Only return ERR_ABRT if you have called tcp_abort from within the
121  *            callback function!
122  *
123  * @note When a connection attempt fails, the error callback is currently called!
124  */
125 typedef err_t (*tcp_connected_fn)(void *arg, struct tcp_pcb *tpcb, err_t err);
126 
127 enum tcp_state {
128   CLOSED      = 0,
129   LISTEN      = 1,
130   SYN_SENT    = 2,
131   SYN_RCVD    = 3,
132   ESTABLISHED = 4,
133   FIN_WAIT_1  = 5,
134   FIN_WAIT_2  = 6,
135   CLOSE_WAIT  = 7,
136   CLOSING     = 8,
137   LAST_ACK    = 9,
138   TIME_WAIT   = 10
139 };
140 
141 #if LWIP_CALLBACK_API
142   /* Function to call when a listener has been connected.
143    * @param arg user-supplied argument (tcp_pcb.callback_arg)
144    * @param pcb a new tcp_pcb that now is connected
145    * @param err an error argument (TODO: that is current always ERR_OK?)
146    * @return ERR_OK: accept the new connection,
147    *                 any other err_t abortsthe new connection
148    */
149 #define DEF_ACCEPT_CALLBACK  tcp_accept_fn accept;
150 #else /* LWIP_CALLBACK_API */
151 #define DEF_ACCEPT_CALLBACK
152 #endif /* LWIP_CALLBACK_API */
153 
154 /**
155  * members common to struct tcp_pcb and struct tcp_listen_pcb
156  */
157 #define TCP_PCB_COMMON(type) \
158   type *next; /* for the linked list */ \
159   enum tcp_state state; /* TCP state */ \
160   u8_t prio; \
161   void *callback_arg; \
162   /* the accept callback for listen- and normal pcbs, if LWIP_CALLBACK_API */ \
163   DEF_ACCEPT_CALLBACK \
164   /* ports are in host byte order */ \
165   u16_t local_port
166 
167 
168 /* the TCP protocol control block */
169 struct tcp_pcb {
170 /** common PCB members */
171   IP_PCB;
172 /** protocol specific PCB members */
173   TCP_PCB_COMMON(struct tcp_pcb);
174 
175   /* ports are in host byte order */
176   u16_t remote_port;
177 
178   u8_t flags;
179 #define TF_ACK_DELAY   ((u8_t)0x01U)   /* Delayed ACK. */
180 #define TF_ACK_NOW     ((u8_t)0x02U)   /* Immediate ACK. */
181 #define TF_INFR        ((u8_t)0x04U)   /* In fast recovery. */
182 #define TF_TIMESTAMP   ((u8_t)0x08U)   /* Timestamp option enabled */
183 #define TF_RXCLOSED    ((u8_t)0x10U)   /* rx closed by tcp_shutdown */
184 #define TF_FIN         ((u8_t)0x20U)   /* Connection was closed locally (FIN segment enqueued). */
185 #define TF_NODELAY     ((u8_t)0x40U)   /* Disable Nagle algorithm */
186 #define TF_NAGLEMEMERR ((u8_t)0x80U)   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
187 
188   /* the rest of the fields are in host byte order
189      as we have to do some math with them */
190   /* receiver variables */
191   u32_t rcv_nxt;   /* next seqno expected */
192   u16_t rcv_wnd;   /* receiver window available */
193   u16_t rcv_ann_wnd; /* receiver window to announce */
194   u32_t rcv_ann_right_edge; /* announced right edge of window */
195 
196   /* Timers */
197   u32_t tmr;
198   u8_t polltmr, pollinterval;
199 
200   /* Retransmission timer. */
201   s16_t rtime;
202 
203   u16_t mss;   /* maximum segment size */
204 
205   /* RTT (round trip time) estimation variables */
206   u32_t rttest; /* RTT estimate in 500ms ticks */
207   u32_t rtseq;  /* sequence number being timed */
208   s16_t sa, sv; /* @todo document this */
209 
210   s16_t rto;    /* retransmission time-out */
211   u8_t nrtx;    /* number of retransmissions */
212 
213   /* fast retransmit/recovery */
214   u32_t lastack; /* Highest acknowledged seqno. */
215   u8_t dupacks;
216 
217   /* congestion avoidance/control variables */
218   u16_t cwnd;
219   u16_t ssthresh;
220 
221   /* sender variables */
222   u32_t snd_nxt;   /* next new seqno to be sent */
223   u16_t snd_wnd;   /* sender window */
224   u32_t snd_wl1, snd_wl2; /* Sequence and acknowledgement numbers of last
225                              window update. */
226   u32_t snd_lbb;       /* Sequence number of next byte to be buffered. */
227 
228   u16_t acked;
229 
230   u16_t snd_buf;   /* Available buffer space for sending (in bytes). */
231 #define TCP_SNDQUEUELEN_OVERFLOW (0xffffU-3)
232   u16_t snd_queuelen; /* Available buffer space for sending (in tcp_segs). */
233 
234 #if TCP_OVERSIZE
235   /* Extra bytes available at the end of the last pbuf in unsent. */
236   u16_t unsent_oversize;
237 #endif /* TCP_OVERSIZE */
238 
239   /* These are ordered by sequence number: */
240   struct tcp_seg *unsent;   /* Unsent (queued) segments. */
241   struct tcp_seg *unacked;  /* Sent but unacknowledged segments. */
242 #if TCP_QUEUE_OOSEQ
243   struct tcp_seg *ooseq;    /* Received out of sequence segments. */
244 #endif /* TCP_QUEUE_OOSEQ */
245 
246   struct pbuf *refused_data; /* Data previously received but not yet taken by upper layer */
247 
248 #if LWIP_CALLBACK_API
249   /* Function to be called when more send buffer space is available. */
250   tcp_sent_fn sent;
251   /* Function to be called when (in-sequence) data has arrived. */
252   tcp_recv_fn recv;
253   /* Function to be called when a connection has been set up. */
254   tcp_connected_fn connected;
255   /* Function which is called periodically. */
256   tcp_poll_fn poll;
257   /* Function to be called whenever a fatal error occurs. */
258   tcp_err_fn errf;
259 #endif /* LWIP_CALLBACK_API */
260 
261 #if LWIP_TCP_TIMESTAMPS
262   u32_t ts_lastacksent;
263   u32_t ts_recent;
264 #endif /* LWIP_TCP_TIMESTAMPS */
265 
266   /* idle time before KEEPALIVE is sent */
267   u32_t keep_idle;
268 #if LWIP_TCP_KEEPALIVE
269   u32_t keep_intvl;
270   u32_t keep_cnt;
271 #endif /* LWIP_TCP_KEEPALIVE */
272 
273   /* Persist timer counter */
274   u32_t persist_cnt;
275   /* Persist timer back-off */
276   u8_t persist_backoff;
277 
278   /* KEEPALIVE counter */
279   u8_t keep_cnt_sent;
280 };
281 
282 struct tcp_pcb_listen {
283 /* Common members of all PCB types */
284   IP_PCB;
285 /* Protocol specific PCB members */
286   TCP_PCB_COMMON(struct tcp_pcb_listen);
287 
288 #if TCP_LISTEN_BACKLOG
289   u8_t backlog;
290   u8_t accepts_pending;
291 #endif /* TCP_LISTEN_BACKLOG */
292 };
293 
294 #if LWIP_EVENT_API
295 
296 enum lwip_event {
297   LWIP_EVENT_ACCEPT,
298   LWIP_EVENT_SENT,
299   LWIP_EVENT_RECV,
300   LWIP_EVENT_CONNECTED,
301   LWIP_EVENT_POLL,
302   LWIP_EVENT_ERR
303 };
304 
305 err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
306          enum lwip_event,
307          struct pbuf *p,
308          u16_t size,
309          err_t err);
310 
311 #endif /* LWIP_EVENT_API */
312 
313 /* Application program's interface: */
314 struct tcp_pcb * tcp_new     (void);
315 
316 void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
317 void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
318 void             tcp_recv    (struct tcp_pcb *pcb, tcp_recv_fn recv);
319 void             tcp_sent    (struct tcp_pcb *pcb, tcp_sent_fn sent);
320 void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
321 void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
322 
323 #define          tcp_mss(pcb)             (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12)  : (pcb)->mss)
324 #define          tcp_sndbuf(pcb)          ((pcb)->snd_buf)
325 #define          tcp_sndqueuelen(pcb)     ((pcb)->snd_queuelen)
326 #define          tcp_nagle_disable(pcb)   ((pcb)->flags |= TF_NODELAY)
327 #define          tcp_nagle_enable(pcb)    ((pcb)->flags &= ~TF_NODELAY)
328 #define          tcp_nagle_disabled(pcb)  (((pcb)->flags & TF_NODELAY) != 0)
329 
330 #if TCP_LISTEN_BACKLOG
331 #define          tcp_accepted(pcb) do { \
332   LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", pcb->state == LISTEN); \
333   (((struct tcp_pcb_listen *)(pcb))->accepts_pending--); } while(0)
334 #else  /* TCP_LISTEN_BACKLOG */
335 #define          tcp_accepted(pcb) LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", \
336                                                pcb->state == LISTEN)
337 #endif /* TCP_LISTEN_BACKLOG */
338 
339 void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
340 err_t            tcp_bind    (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
341                               u16_t port);
342 err_t            tcp_connect (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
343                               u16_t port, tcp_connected_fn connected);
344 
345 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
346 #define          tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
347 
348 void             tcp_abort (struct tcp_pcb *pcb);
349 err_t            tcp_close   (struct tcp_pcb *pcb);
350 err_t            tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx);
351 
352 /* Flags for "apiflags" parameter in tcp_write */
353 #define TCP_WRITE_FLAG_COPY 0x01
354 #define TCP_WRITE_FLAG_MORE 0x02
355 
356 err_t            tcp_write   (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
357                               u8_t apiflags);
358 
359 void             tcp_setprio (struct tcp_pcb *pcb, u8_t prio);
360 
361 #define TCP_PRIO_MIN    1
362 #define TCP_PRIO_NORMAL 64
363 #define TCP_PRIO_MAX    127
364 
365 err_t            tcp_output  (struct tcp_pcb *pcb);
366 
367 
368 const char* tcp_debug_state_str(enum tcp_state s);
369 
370 
371 #ifdef __cplusplus
372 }
373 #endif
374 
375 #endif /* LWIP_TCP */
376 
377 #endif /* __LWIP_TCP_H__ */
378