tcp.h

00001 /*
00002  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00003  * All rights reserved. 
00004  * 
00005  * Redistribution and use in source and binary forms, with or without modification, 
00006  * are permitted provided that the following conditions are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright notice,
00009  *    this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright notice,
00011  *    this list of conditions and the following disclaimer in the documentation
00012  *    and/or other materials provided with the distribution.
00013  * 3. The name of the author may not be used to endorse or promote products
00014  *    derived from this software without specific prior written permission. 
00015  *
00016  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
00017  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
00018  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
00019  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
00020  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
00021  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
00022  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
00023  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
00024  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
00025  * OF SUCH DAMAGE.
00026  *
00027  * This file is part of the lwIP TCP/IP stack.
00028  * 
00029  * Author: Adam Dunkels <adam@sics.se>
00030  *
00031  */
00032 #ifndef __LWIP_TCP_H__
00033 #define __LWIP_TCP_H__
00034 
00035 #include "lwip/opt.h"
00036 
00037 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
00038 
00039 #include "lwip/sys.h"
00040 #include "lwip/mem.h"
00041 #include "lwip/pbuf.h"
00042 #include "lwip/ip.h"
00043 #include "lwip/icmp.h"
00044 #include "lwip/err.h"
00045 
00046 #ifdef __cplusplus
00047 extern "C" {
00048 #endif
00049 
00050 struct tcp_pcb;
00051 
00052 /** Function prototype for tcp accept callback functions. Called when a new
00053  * connection can be accepted on a listening pcb.
00054  *
00055  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00056  * @param newpcb The new connection pcb
00057  * @param err An error code if there has been an error accepting.
00058  *            Only return ERR_ABRT if you have called tcp_abort from within the
00059  *            callback function!
00060  */
00061 typedef err_t (*tcp_accept_fn)(void *arg, struct tcp_pcb *newpcb, err_t err);
00062 
00063 /** Function prototype for tcp receive callback functions. Called when data has
00064  * been received.
00065  *
00066  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00067  * @param tpcb The connection pcb which received data
00068  * @param p The received data (or NULL when the connection has been closed!)
00069  * @param err An error code if there has been an error receiving
00070  *            Only return ERR_ABRT if you have called tcp_abort from within the
00071  *            callback function!
00072  */
00073 typedef err_t (*tcp_recv_fn)(void *arg, struct tcp_pcb *tpcb,
00074                              struct pbuf *p, err_t err);
00075 
00076 /** Function prototype for tcp sent callback functions. Called when sent data has
00077  * been acknowledged by the remote side. Use it to free corresponding resources.
00078  * This also means that the pcb has now space available to send new data.
00079  *
00080  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00081  * @param tpcb The connection pcb for which data has been acknowledged
00082  * @param len The amount of bytes acknowledged
00083  * @return ERR_OK: try to send some data by calling tcp_output
00084  *            Only return ERR_ABRT if you have called tcp_abort from within the
00085  *            callback function!
00086  */
00087 typedef err_t (*tcp_sent_fn)(void *arg, struct tcp_pcb *tpcb,
00088                               u16_t len);
00089 
00090 /** Function prototype for tcp poll callback functions. Called periodically as
00091  * specified by @see tcp_poll.
00092  *
00093  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00094  * @param tpcb tcp pcb
00095  * @return ERR_OK: try to send some data by calling tcp_output
00096  *            Only return ERR_ABRT if you have called tcp_abort from within the
00097  *            callback function!
00098  */
00099 typedef err_t (*tcp_poll_fn)(void *arg, struct tcp_pcb *tpcb);
00100 
00101 /** Function prototype for tcp error callback functions. Called when the pcb
00102  * receives a RST or is unexpectedly closed for any other reason.
00103  *
00104  * @note The corresponding pcb is already freed when this callback is called!
00105  *
00106  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00107  * @param err Error code to indicate why the pcb has been closed
00108  *            ERR_ABRT: aborted through tcp_abort or by a TCP timer
00109  *            ERR_RST: the connection was reset by the remote host
00110  */
00111 typedef void  (*tcp_err_fn)(void *arg, err_t err);
00112 
00113 /** Function prototype for tcp connected callback functions. Called when a pcb
00114  * is connected to the remote side after initiating a connection attempt by
00115  * calling tcp_connect().
00116  *
00117  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00118  * @param tpcb The connection pcb which is connected
00119  * @param err An unused error code, always ERR_OK currently ;-) TODO!
00120  *            Only return ERR_ABRT if you have called tcp_abort from within the
00121  *            callback function!
00122  *
00123  * @note When a connection attempt fails, the error callback is currently called!
00124  */
00125 typedef err_t (*tcp_connected_fn)(void *arg, struct tcp_pcb *tpcb, err_t err);
00126 
00127 enum tcp_state {
00128   CLOSED      = 0,
00129   LISTEN      = 1,
00130   SYN_SENT    = 2,
00131   SYN_RCVD    = 3,
00132   ESTABLISHED = 4,
00133   FIN_WAIT_1  = 5,
00134   FIN_WAIT_2  = 6,
00135   CLOSE_WAIT  = 7,
00136   CLOSING     = 8,
00137   LAST_ACK    = 9,
00138   TIME_WAIT   = 10
00139 };
00140 
00141 #if LWIP_CALLBACK_API
00142   /* Function to call when a listener has been connected.
00143    * @param arg user-supplied argument (tcp_pcb.callback_arg)
00144    * @param pcb a new tcp_pcb that now is connected
00145    * @param err an error argument (TODO: that is current always ERR_OK?)
00146    * @return ERR_OK: accept the new connection,
00147    *                 any other err_t abortsthe new connection
00148    */
00149 #define DEF_ACCEPT_CALLBACK  tcp_accept_fn accept;
00150 #else /* LWIP_CALLBACK_API */
00151 #define DEF_ACCEPT_CALLBACK
00152 #endif /* LWIP_CALLBACK_API */
00153 
00154 /**
00155  * members common to struct tcp_pcb and struct tcp_listen_pcb
00156  */
00157 #define TCP_PCB_COMMON(type) \
00158   type *next; /* for the linked list */ \
00159   enum tcp_state state; /* TCP state */ \
00160   u8_t prio; \
00161   void *callback_arg; \
00162   /* the accept callback for listen- and normal pcbs, if LWIP_CALLBACK_API */ \
00163   DEF_ACCEPT_CALLBACK \
00164   /* ports are in host byte order */ \
00165   u16_t local_port
00166 
00167 
00168 /* the TCP protocol control block */
00169 struct tcp_pcb {
00170 /** common PCB members */
00171   IP_PCB;
00172 /** protocol specific PCB members */
00173   TCP_PCB_COMMON(struct tcp_pcb);
00174 
00175   /* ports are in host byte order */
00176   u16_t remote_port;
00177   
00178   u8_t flags;
00179 #define TF_ACK_DELAY   ((u8_t)0x01U)   /* Delayed ACK. */
00180 #define TF_ACK_NOW     ((u8_t)0x02U)   /* Immediate ACK. */
00181 #define TF_INFR        ((u8_t)0x04U)   /* In fast recovery. */
00182 #define TF_TIMESTAMP   ((u8_t)0x08U)   /* Timestamp option enabled */
00183 #define TF_RXCLOSED    ((u8_t)0x10U)   /* rx closed by tcp_shutdown */
00184 #define TF_FIN         ((u8_t)0x20U)   /* Connection was closed locally (FIN segment enqueued). */
00185 #define TF_NODELAY     ((u8_t)0x40U)   /* Disable Nagle algorithm */
00186 #define TF_NAGLEMEMERR ((u8_t)0x80U)   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
00187 
00188   /* the rest of the fields are in host byte order
00189      as we have to do some math with them */
00190   /* receiver variables */
00191   u32_t rcv_nxt;   /* next seqno expected */
00192   u16_t rcv_wnd;   /* receiver window available */
00193   u16_t rcv_ann_wnd; /* receiver window to announce */
00194   u32_t rcv_ann_right_edge; /* announced right edge of window */
00195 
00196   /* Timers */
00197   u32_t tmr;
00198   u8_t polltmr, pollinterval;
00199   
00200   /* Retransmission timer. */
00201   s16_t rtime;
00202   
00203   u16_t mss;   /* maximum segment size */
00204   
00205   /* RTT (round trip time) estimation variables */
00206   u32_t rttest; /* RTT estimate in 500ms ticks */
00207   u32_t rtseq;  /* sequence number being timed */
00208   s16_t sa, sv; /* @todo document this */
00209 
00210   s16_t rto;    /* retransmission time-out */
00211   u8_t nrtx;    /* number of retransmissions */
00212 
00213   /* fast retransmit/recovery */
00214   u32_t lastack; /* Highest acknowledged seqno. */
00215   u8_t dupacks;
00216   
00217   /* congestion avoidance/control variables */
00218   u16_t cwnd;  
00219   u16_t ssthresh;
00220 
00221   /* sender variables */
00222   u32_t snd_nxt;   /* next new seqno to be sent */
00223   u16_t snd_wnd;   /* sender window */
00224   u32_t snd_wl1, snd_wl2; /* Sequence and acknowledgement numbers of last
00225                              window update. */
00226   u32_t snd_lbb;       /* Sequence number of next byte to be buffered. */
00227 
00228   u16_t acked;
00229   
00230   u16_t snd_buf;   /* Available buffer space for sending (in bytes). */
00231 #define TCP_SNDQUEUELEN_OVERFLOW (0xffff-3)
00232   u16_t snd_queuelen; /* Available buffer space for sending (in tcp_segs). */
00233 
00234 #if TCP_OVERSIZE
00235   /* Extra bytes available at the end of the last pbuf in unsent. */
00236   u16_t unsent_oversize;
00237 #endif /* TCP_OVERSIZE */ 
00238 
00239   /* These are ordered by sequence number: */
00240   struct tcp_seg *unsent;   /* Unsent (queued) segments. */
00241   struct tcp_seg *unacked;  /* Sent but unacknowledged segments. */
00242 #if TCP_QUEUE_OOSEQ  
00243   struct tcp_seg *ooseq;    /* Received out of sequence segments. */
00244 #endif /* TCP_QUEUE_OOSEQ */
00245 
00246   struct pbuf *refused_data; /* Data previously received but not yet taken by upper layer */
00247 
00248 #if LWIP_CALLBACK_API
00249   /* Function to be called when more send buffer space is available. */
00250   tcp_sent_fn sent;
00251   /* Function to be called when (in-sequence) data has arrived. */
00252   tcp_recv_fn recv;
00253   /* Function to be called when a connection has been set up. */
00254   tcp_connected_fn connected;
00255   /* Function which is called periodically. */
00256   tcp_poll_fn poll;
00257   /* Function to be called whenever a fatal error occurs. */
00258   tcp_err_fn errf;
00259 #endif /* LWIP_CALLBACK_API */
00260 
00261 #if LWIP_TCP_TIMESTAMPS
00262   u32_t ts_lastacksent;
00263   u32_t ts_recent;
00264 #endif /* LWIP_TCP_TIMESTAMPS */
00265 
00266   /* idle time before KEEPALIVE is sent */
00267   u32_t keep_idle;
00268 #if LWIP_TCP_KEEPALIVE
00269   u32_t keep_intvl;
00270   u32_t keep_cnt;
00271 #endif /* LWIP_TCP_KEEPALIVE */
00272   
00273   /* Persist timer counter */
00274   u32_t persist_cnt;
00275   /* Persist timer back-off */
00276   u8_t persist_backoff;
00277 
00278   /* KEEPALIVE counter */
00279   u8_t keep_cnt_sent;
00280 };
00281 
00282 struct tcp_pcb_listen {  
00283 /* Common members of all PCB types */
00284   IP_PCB;
00285 /* Protocol specific PCB members */
00286   TCP_PCB_COMMON(struct tcp_pcb_listen);
00287 
00288 #if TCP_LISTEN_BACKLOG
00289   u8_t backlog;
00290   u8_t accepts_pending;
00291 #endif /* TCP_LISTEN_BACKLOG */
00292 };
00293 
00294 #if LWIP_EVENT_API
00295 
00296 enum lwip_event {
00297   LWIP_EVENT_ACCEPT,
00298   LWIP_EVENT_SENT,
00299   LWIP_EVENT_RECV,
00300   LWIP_EVENT_CONNECTED,
00301   LWIP_EVENT_POLL,
00302   LWIP_EVENT_ERR
00303 };
00304 
00305 err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
00306          enum lwip_event,
00307          struct pbuf *p,
00308          u16_t size,
00309          err_t err);
00310 
00311 #endif /* LWIP_EVENT_API */
00312 
00313 /* Application program's interface: */
00314 struct tcp_pcb * tcp_new     (void);
00315 
00316 void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
00317 void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
00318 void             tcp_recv    (struct tcp_pcb *pcb, tcp_recv_fn recv);
00319 void             tcp_sent    (struct tcp_pcb *pcb, tcp_sent_fn sent);
00320 void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
00321 void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
00322 
00323 #define          tcp_mss(pcb)             (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12)  : (pcb)->mss)
00324 #define          tcp_sndbuf(pcb)          ((pcb)->snd_buf)
00325 #define          tcp_sndqueuelen(pcb)     ((pcb)->snd_queuelen)
00326 #define          tcp_nagle_disable(pcb)   ((pcb)->flags |= TF_NODELAY)
00327 #define          tcp_nagle_enable(pcb)    ((pcb)->flags &= ~TF_NODELAY)
00328 #define          tcp_nagle_disabled(pcb)  (((pcb)->flags & TF_NODELAY) != 0)
00329 
00330 #if TCP_LISTEN_BACKLOG
00331 #define          tcp_accepted(pcb) do { \
00332   LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", pcb->state == LISTEN); \
00333   (((struct tcp_pcb_listen *)(pcb))->accepts_pending--); } while(0)
00334 #else  /* TCP_LISTEN_BACKLOG */
00335 #define          tcp_accepted(pcb) LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", \
00336                                                pcb->state == LISTEN)
00337 #endif /* TCP_LISTEN_BACKLOG */
00338 
00339 void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
00340 err_t            tcp_bind    (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
00341                               u16_t port);
00342 err_t            tcp_connect (struct tcp_pcb *pcb, ip_addr_t *ipaddr,
00343                               u16_t port, tcp_connected_fn connected);
00344 
00345 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
00346 #define          tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
00347 
00348 void             tcp_abort (struct tcp_pcb *pcb);
00349 err_t            tcp_close   (struct tcp_pcb *pcb);
00350 err_t            tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx);
00351 
00352 /* Flags for "apiflags" parameter in tcp_write */
00353 #define TCP_WRITE_FLAG_COPY 0x01
00354 #define TCP_WRITE_FLAG_MORE 0x02
00355 
00356 err_t            tcp_write   (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
00357                               u8_t apiflags);
00358 
00359 void             tcp_setprio (struct tcp_pcb *pcb, u8_t prio);
00360 
00361 #define TCP_PRIO_MIN    1
00362 #define TCP_PRIO_NORMAL 64
00363 #define TCP_PRIO_MAX    127
00364 
00365 err_t            tcp_output  (struct tcp_pcb *pcb);
00366 
00367 
00368 const char* tcp_debug_state_str(enum tcp_state s);
00369 
00370 
00371 #ifdef __cplusplus
00372 }
00373 #endif
00374 
00375 #endif /* LWIP_TCP */
00376 
00377 #endif /* __LWIP_TCP_H__ */