tcp.h

00001 /**
00002  * @file
00003  * TCP API (to be used from TCPIP thread)\n
00004  * See also @ref tcp_raw
00005  */
00006 
00007 /*
00008  * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
00009  * All rights reserved.
00010  *
00011  * Redistribution and use in source and binary forms, with or without modification,
00012  * are permitted provided that the following conditions are met:
00013  *
00014  * 1. Redistributions of source code must retain the above copyright notice,
00015  *    this list of conditions and the following disclaimer.
00016  * 2. Redistributions in binary form must reproduce the above copyright notice,
00017  *    this list of conditions and the following disclaimer in the documentation
00018  *    and/or other materials provided with the distribution.
00019  * 3. The name of the author may not be used to endorse or promote products
00020  *    derived from this software without specific prior written permission.
00021  *
00022  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00023  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00024  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00025  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00026  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00027  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00028  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00029  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00030  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00031  * OF SUCH DAMAGE.
00032  *
00033  * This file is part of the lwIP TCP/IP stack.
00034  *
00035  * Author: Adam Dunkels <adam@sics.se>
00036  *
00037  */
00038 #ifndef LWIP_HDR_TCP_H
00039 #define LWIP_HDR_TCP_H
00040 
00041 #include "lwip/opt.h"
00042 
00043 #if LWIP_TCP /* don't build if not configured for use in lwipopts.h */
00044 
00045 #include "lwip/mem.h"
00046 #include "lwip/pbuf.h"
00047 #include "lwip/ip.h"
00048 #include "lwip/icmp.h"
00049 #include "lwip/err.h"
00050 #include "lwip/ip6.h"
00051 #include "lwip/ip6_addr.h"
00052 
00053 #ifdef __cplusplus
00054 extern "C" {
00055 #endif
00056 
00057 struct tcp_pcb;
00058 
00059 /** Function prototype for tcp accept callback functions. Called when a new
00060  * connection can be accepted on a listening pcb.
00061  *
00062  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00063  * @param newpcb The new connection pcb
00064  * @param err An error code if there has been an error accepting.
00065  *            Only return ERR_ABRT if you have called tcp_abort from within the
00066  *            callback function!
00067  */
00068 typedef err_t (*tcp_accept_fn)(void *arg, struct tcp_pcb *newpcb, err_t err);
00069 
00070 /** Function prototype for tcp receive callback functions. Called when data has
00071  * been received.
00072  *
00073  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00074  * @param tpcb The connection pcb which received data
00075  * @param p The received data (or NULL when the connection has been closed!)
00076  * @param err An error code if there has been an error receiving
00077  *            Only return ERR_ABRT if you have called tcp_abort from within the
00078  *            callback function!
00079  */
00080 typedef err_t (*tcp_recv_fn)(void *arg, struct tcp_pcb *tpcb,
00081                              struct pbuf *p, err_t err);
00082 
00083 /** Function prototype for tcp sent callback functions. Called when sent data has
00084  * been acknowledged by the remote side. Use it to free corresponding resources.
00085  * This also means that the pcb has now space available to send new data.
00086  *
00087  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00088  * @param tpcb The connection pcb for which data has been acknowledged
00089  * @param len The amount of bytes acknowledged
00090  * @return ERR_OK: try to send some data by calling tcp_output
00091  *            Only return ERR_ABRT if you have called tcp_abort from within the
00092  *            callback function!
00093  */
00094 typedef err_t (*tcp_sent_fn)(void *arg, struct tcp_pcb *tpcb,
00095                               u16_t len);
00096 
00097 /** Function prototype for tcp poll callback functions. Called periodically as
00098  * specified by @see tcp_poll.
00099  *
00100  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00101  * @param tpcb tcp pcb
00102  * @return ERR_OK: try to send some data by calling tcp_output
00103  *            Only return ERR_ABRT if you have called tcp_abort from within the
00104  *            callback function!
00105  */
00106 typedef err_t (*tcp_poll_fn)(void *arg, struct tcp_pcb *tpcb);
00107 
00108 /** Function prototype for tcp error callback functions. Called when the pcb
00109  * receives a RST or is unexpectedly closed for any other reason.
00110  *
00111  * @note The corresponding pcb is already freed when this callback is called!
00112  *
00113  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00114  * @param err Error code to indicate why the pcb has been closed
00115  *            ERR_ABRT: aborted through tcp_abort or by a TCP timer
00116  *            ERR_RST: the connection was reset by the remote host
00117  */
00118 typedef void  (*tcp_err_fn)(void *arg, err_t err);
00119 
00120 /** Function prototype for tcp connected callback functions. Called when a pcb
00121  * is connected to the remote side after initiating a connection attempt by
00122  * calling tcp_connect().
00123  *
00124  * @param arg Additional argument to pass to the callback function (@see tcp_arg())
00125  * @param tpcb The connection pcb which is connected
00126  * @param err An unused error code, always ERR_OK currently ;-) @todo!
00127  *            Only return ERR_ABRT if you have called tcp_abort from within the
00128  *            callback function!
00129  *
00130  * @note When a connection attempt fails, the error callback is currently called!
00131  */
00132 typedef err_t (*tcp_connected_fn)(void *arg, struct tcp_pcb *tpcb, err_t err);
00133 
00134 #if LWIP_WND_SCALE
00135 #define RCV_WND_SCALE(pcb, wnd) (((wnd) >> (pcb)->rcv_scale))
00136 #define SND_WND_SCALE(pcb, wnd) (((wnd) << (pcb)->snd_scale))
00137 #define TCPWND16(x)             ((u16_t)LWIP_MIN((x), 0xFFFF))
00138 #define TCP_WND_MAX(pcb)        ((tcpwnd_size_t)(((pcb)->flags & TF_WND_SCALE) ? TCP_WND : TCPWND16(TCP_WND)))
00139 typedef u32_t tcpwnd_size_t;
00140 #else
00141 #define RCV_WND_SCALE(pcb, wnd) (wnd)
00142 #define SND_WND_SCALE(pcb, wnd) (wnd)
00143 #define TCPWND16(x)             (x)
00144 #define TCP_WND_MAX(pcb)        TCP_WND
00145 typedef u16_t tcpwnd_size_t;
00146 #endif
00147 
00148 #if LWIP_WND_SCALE || TCP_LISTEN_BACKLOG
00149 typedef u16_t tcpflags_t;
00150 #else
00151 typedef u8_t tcpflags_t;
00152 #endif
00153 
00154 enum tcp_state {
00155   CLOSED      = 0,
00156   LISTEN      = 1,
00157   SYN_SENT    = 2,
00158   SYN_RCVD    = 3,
00159   ESTABLISHED = 4,
00160   FIN_WAIT_1  = 5,
00161   FIN_WAIT_2  = 6,
00162   CLOSE_WAIT  = 7,
00163   CLOSING     = 8,
00164   LAST_ACK    = 9,
00165   TIME_WAIT   = 10
00166 };
00167 
00168 /**
00169  * members common to struct tcp_pcb and struct tcp_listen_pcb
00170  */
00171 #define TCP_PCB_COMMON(type) \
00172   type *next; /* for the linked list */ \
00173   void *callback_arg; \
00174   enum tcp_state state; /* TCP state */ \
00175   u8_t prio; \
00176   /* ports are in host byte order */ \
00177   u16_t local_port
00178 
00179 
00180 /** the TCP protocol control block for listening pcbs */
00181 struct tcp_pcb_listen {
00182 /** Common members of all PCB types */
00183   IP_PCB;
00184 /** Protocol specific PCB members */
00185   TCP_PCB_COMMON(struct tcp_pcb_listen);
00186 
00187 #if LWIP_CALLBACK_API
00188   /* Function to call when a listener has been connected. */
00189   tcp_accept_fn accept;
00190 #endif /* LWIP_CALLBACK_API */
00191 
00192 #if TCP_LISTEN_BACKLOG
00193   u8_t backlog;
00194   u8_t accepts_pending;
00195 #endif /* TCP_LISTEN_BACKLOG */
00196 };
00197 
00198 
00199 /** the TCP protocol control block */
00200 struct tcp_pcb {
00201 /** common PCB members */
00202   IP_PCB;
00203 /** protocol specific PCB members */
00204   TCP_PCB_COMMON(struct tcp_pcb);
00205 
00206   /* ports are in host byte order */
00207   u16_t remote_port;
00208 
00209   tcpflags_t flags;
00210 #define TF_ACK_DELAY   0x01U   /* Delayed ACK. */
00211 #define TF_ACK_NOW     0x02U   /* Immediate ACK. */
00212 #define TF_INFR        0x04U   /* In fast recovery. */
00213 #define TF_TIMESTAMP   0x08U   /* Timestamp option enabled */
00214 #define TF_RXCLOSED    0x10U   /* rx closed by tcp_shutdown */
00215 #define TF_FIN         0x20U   /* Connection was closed locally (FIN segment enqueued). */
00216 #define TF_NODELAY     0x40U   /* Disable Nagle algorithm */
00217 #define TF_NAGLEMEMERR 0x80U   /* nagle enabled, memerr, try to output to prevent delayed ACK to happen */
00218 #if LWIP_WND_SCALE
00219 #define TF_WND_SCALE   0x0100U /* Window Scale option enabled */
00220 #endif
00221 #if TCP_LISTEN_BACKLOG
00222 #define TF_BACKLOGPEND 0x0200U /* If this is set, a connection pcb has increased the backlog on its listener */
00223 #endif
00224 
00225   /* the rest of the fields are in host byte order
00226      as we have to do some math with them */
00227 
00228   /* Timers */
00229   u8_t polltmr, pollinterval;
00230   u8_t last_timer;
00231   u32_t tmr;
00232 
00233   /* receiver variables */
00234   u32_t rcv_nxt;   /* next seqno expected */
00235   tcpwnd_size_t rcv_wnd;   /* receiver window available */
00236   tcpwnd_size_t rcv_ann_wnd; /* receiver window to announce */
00237   u32_t rcv_ann_right_edge; /* announced right edge of window */
00238 
00239   /* Retransmission timer. */
00240   s16_t rtime;
00241 
00242   u16_t mss;   /* maximum segment size */
00243 
00244   /* RTT (round trip time) estimation variables */
00245   u32_t rttest; /* RTT estimate in 500ms ticks */
00246   u32_t rtseq;  /* sequence number being timed */
00247   s16_t sa, sv; /* @todo document this */
00248 
00249   s16_t rto;    /* retransmission time-out */
00250   u8_t nrtx;    /* number of retransmissions */
00251 
00252   /* fast retransmit/recovery */
00253   u8_t dupacks;
00254   u32_t lastack; /* Highest acknowledged seqno. */
00255 
00256   /* congestion avoidance/control variables */
00257   tcpwnd_size_t cwnd;
00258   tcpwnd_size_t ssthresh;
00259 
00260   /* sender variables */
00261   u32_t snd_nxt;   /* next new seqno to be sent */
00262   u32_t snd_wl1, snd_wl2; /* Sequence and acknowledgement numbers of last
00263                              window update. */
00264   u32_t snd_lbb;       /* Sequence number of next byte to be buffered. */
00265   tcpwnd_size_t snd_wnd;   /* sender window */
00266   tcpwnd_size_t snd_wnd_max; /* the maximum sender window announced by the remote host */
00267 
00268   tcpwnd_size_t snd_buf;   /* Available buffer space for sending (in bytes). */
00269 #define TCP_SNDQUEUELEN_OVERFLOW (0xffffU-3)
00270   u16_t snd_queuelen; /* Number of pbufs currently in the send buffer. */
00271 
00272 #if TCP_OVERSIZE
00273   /* Extra bytes available at the end of the last pbuf in unsent. */
00274   u16_t unsent_oversize;
00275 #endif /* TCP_OVERSIZE */
00276 
00277   /* These are ordered by sequence number: */
00278   struct tcp_seg *unsent;   /* Unsent (queued) segments. */
00279   struct tcp_seg *unacked;  /* Sent but unacknowledged segments. */
00280 #if TCP_QUEUE_OOSEQ
00281   struct tcp_seg *ooseq;    /* Received out of sequence segments. */
00282 #endif /* TCP_QUEUE_OOSEQ */
00283 
00284   struct pbuf *refused_data; /* Data previously received but not yet taken by upper layer */
00285 
00286 #if LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG
00287   struct tcp_pcb_listen* listener;
00288 #endif /* LWIP_CALLBACK_API || TCP_LISTEN_BACKLOG */
00289 
00290 #if LWIP_CALLBACK_API
00291   /* Function to be called when more send buffer space is available. */
00292   tcp_sent_fn sent;
00293   /* Function to be called when (in-sequence) data has arrived. */
00294   tcp_recv_fn recv;
00295   /* Function to be called when a connection has been set up. */
00296   tcp_connected_fn connected;
00297   /* Function which is called periodically. */
00298   tcp_poll_fn poll;
00299   /* Function to be called whenever a fatal error occurs. */
00300   tcp_err_fn errf;
00301 #endif /* LWIP_CALLBACK_API */
00302 
00303 #if LWIP_TCP_TIMESTAMPS
00304   u32_t ts_lastacksent;
00305   u32_t ts_recent;
00306 #endif /* LWIP_TCP_TIMESTAMPS */
00307 
00308   /* idle time before KEEPALIVE is sent */
00309   u32_t keep_idle;
00310 #if LWIP_TCP_KEEPALIVE
00311   u32_t keep_intvl;
00312   u32_t keep_cnt;
00313 #endif /* LWIP_TCP_KEEPALIVE */
00314 
00315   /* Persist timer counter */
00316   u8_t persist_cnt;
00317   /* Persist timer back-off */
00318   u8_t persist_backoff;
00319 
00320   /* KEEPALIVE counter */
00321   u8_t keep_cnt_sent;
00322 
00323 #if LWIP_WND_SCALE
00324   u8_t snd_scale;
00325   u8_t rcv_scale;
00326 #endif
00327 };
00328 
00329 #if LWIP_EVENT_API
00330 
00331 enum lwip_event {
00332   LWIP_EVENT_ACCEPT,
00333   LWIP_EVENT_SENT,
00334   LWIP_EVENT_RECV,
00335   LWIP_EVENT_CONNECTED,
00336   LWIP_EVENT_POLL,
00337   LWIP_EVENT_ERR
00338 };
00339 
00340 err_t lwip_tcp_event(void *arg, struct tcp_pcb *pcb,
00341          enum lwip_event,
00342          struct pbuf *p,
00343          u16_t size,
00344          err_t err);
00345 
00346 #endif /* LWIP_EVENT_API */
00347 
00348 /* Application program's interface: */
00349 struct tcp_pcb * tcp_new     (void);
00350 struct tcp_pcb * tcp_new_ip_type (u8_t type);
00351 
00352 void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
00353 void             tcp_accept  (struct tcp_pcb *pcb, tcp_accept_fn accept);
00354 void             tcp_recv    (struct tcp_pcb *pcb, tcp_recv_fn recv);
00355 void             tcp_sent    (struct tcp_pcb *pcb, tcp_sent_fn sent);
00356 void             tcp_poll    (struct tcp_pcb *pcb, tcp_poll_fn poll, u8_t interval);
00357 void             tcp_err     (struct tcp_pcb *pcb, tcp_err_fn err);
00358 
00359 #define          tcp_mss(pcb)             (((pcb)->flags & TF_TIMESTAMP) ? ((pcb)->mss - 12)  : (pcb)->mss)
00360 #define          tcp_sndbuf(pcb)          (TCPWND16((pcb)->snd_buf))
00361 #define          tcp_sndqueuelen(pcb)     ((pcb)->snd_queuelen)
00362 /** @ingroup tcp_raw */
00363 #define          tcp_nagle_disable(pcb)   ((pcb)->flags |= TF_NODELAY)
00364 /** @ingroup tcp_raw */
00365 #define          tcp_nagle_enable(pcb)    ((pcb)->flags = (tcpflags_t)((pcb)->flags & ~TF_NODELAY))
00366 /** @ingroup tcp_raw */
00367 #define          tcp_nagle_disabled(pcb)  (((pcb)->flags & TF_NODELAY) != 0)
00368 
00369 #if TCP_LISTEN_BACKLOG
00370 #define          tcp_backlog_set(pcb, new_backlog) do { \
00371   LWIP_ASSERT("pcb->state == LISTEN (called for wrong pcb?)", (pcb)->state == LISTEN); \
00372   ((struct tcp_pcb_listen *)(pcb))->backlog = ((new_backlog) ? (new_backlog) : 1); } while(0)
00373 void             tcp_backlog_delayed(struct tcp_pcb* pcb);
00374 void             tcp_backlog_accepted(struct tcp_pcb* pcb);
00375 #else  /* TCP_LISTEN_BACKLOG */
00376 #define          tcp_backlog_set(pcb, new_backlog)
00377 #define          tcp_backlog_delayed(pcb)
00378 #define          tcp_backlog_accepted(pcb)
00379 #endif /* TCP_LISTEN_BACKLOG */
00380 #define          tcp_accepted(pcb) /* compatibility define, not needed any more */
00381 
00382 void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
00383 err_t            tcp_bind    (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
00384                               u16_t port);
00385 err_t            tcp_connect (struct tcp_pcb *pcb, const ip_addr_t *ipaddr,
00386                               u16_t port, tcp_connected_fn connected);
00387 
00388 struct tcp_pcb * tcp_listen_with_backlog(struct tcp_pcb *pcb, u8_t backlog);
00389 /** @ingroup tcp_raw */
00390 #define          tcp_listen(pcb) tcp_listen_with_backlog(pcb, TCP_DEFAULT_LISTEN_BACKLOG)
00391 
00392 void             tcp_abort (struct tcp_pcb *pcb);
00393 err_t            tcp_close   (struct tcp_pcb *pcb);
00394 err_t            tcp_shutdown(struct tcp_pcb *pcb, int shut_rx, int shut_tx);
00395 
00396 /* Flags for "apiflags" parameter in tcp_write */
00397 #define TCP_WRITE_FLAG_COPY 0x01
00398 #define TCP_WRITE_FLAG_MORE 0x02
00399 
00400 err_t            tcp_write   (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
00401                               u8_t apiflags);
00402 
00403 void             tcp_setprio (struct tcp_pcb *pcb, u8_t prio);
00404 
00405 #define TCP_PRIO_MIN    1
00406 #define TCP_PRIO_NORMAL 64
00407 #define TCP_PRIO_MAX    127
00408 
00409 err_t            tcp_output  (struct tcp_pcb *pcb);
00410 
00411 
00412 const char* tcp_debug_state_str(enum tcp_state s);
00413 
00414 /* for compatibility with older implementation */
00415 #define tcp_new_ip6() tcp_new_ip_type(IPADDR_TYPE_V6)
00416 
00417 #ifdef __cplusplus
00418 }
00419 #endif
00420 
00421 #endif /* LWIP_TCP */
00422 
00423 #endif /* LWIP_HDR_TCP_H */