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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 (at) 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