tcp_impl.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_IMPL_H__
00033 #define __LWIP_TCP_IMPL_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/tcp.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 /* Functions for interfacing with TCP: */
00051 
00052 /* Lower layer interface to TCP: */
00053 void             tcp_init    (void);  /* Initialize this module. */
00054 void             tcp_tmr     (void);  /* Must be called every
00055                                          TCP_TMR_INTERVAL
00056                                          ms. (Typically 250 ms). */
00057 /* It is also possible to call these two functions at the right
00058    intervals (instead of calling tcp_tmr()). */
00059 void             tcp_slowtmr (void);
00060 void             tcp_fasttmr (void);
00061 
00062 
00063 /* Only used by IP to pass a TCP segment to TCP: */
00064 void             tcp_input   (struct pbuf *p, struct netif *inp);
00065 /* Used within the TCP code only: */
00066 struct tcp_pcb * tcp_alloc   (u8_t prio);
00067 void             tcp_abandon (struct tcp_pcb *pcb, int reset);
00068 err_t            tcp_send_empty_ack(struct tcp_pcb *pcb);
00069 void             tcp_rexmit  (struct tcp_pcb *pcb);
00070 void             tcp_rexmit_rto  (struct tcp_pcb *pcb);
00071 void             tcp_rexmit_fast (struct tcp_pcb *pcb);
00072 u32_t            tcp_update_rcv_ann_wnd(struct tcp_pcb *pcb);
00073 err_t            tcp_process_refused_data(struct tcp_pcb *pcb);
00074 
00075 /**
00076  * This is the Nagle algorithm: try to combine user data to send as few TCP
00077  * segments as possible. Only send if
00078  * - no previously transmitted data on the connection remains unacknowledged or
00079  * - the TF_NODELAY flag is set (nagle algorithm turned off for this pcb) or
00080  * - the only unsent segment is at least pcb->mss bytes long (or there is more
00081  *   than one unsent segment - with lwIP, this can happen although unsent->len < mss)
00082  * - or if we are in fast-retransmit (TF_INFR)
00083  */
00084 #define tcp_do_output_nagle(tpcb) ((((tpcb)->unacked == NULL) || \
00085                             ((tpcb)->flags & (TF_NODELAY | TF_INFR)) || \
00086                             (((tpcb)->unsent != NULL) && (((tpcb)->unsent->next != NULL) || \
00087                               ((tpcb)->unsent->len >= (tpcb)->mss))) || \
00088                             ((tcp_sndbuf(tpcb) == 0) || (tcp_sndqueuelen(tpcb) >= TCP_SND_QUEUELEN)) \
00089                             ) ? 1 : 0)
00090 #define tcp_output_nagle(tpcb) (tcp_do_output_nagle(tpcb) ? tcp_output(tpcb) : ERR_OK)
00091 
00092 
00093 #define TCP_SEQ_LT(a,b)     ((s32_t)((u32_t)(a) - (u32_t)(b)) < 0)
00094 #define TCP_SEQ_LEQ(a,b)    ((s32_t)((u32_t)(a) - (u32_t)(b)) <= 0)
00095 #define TCP_SEQ_GT(a,b)     ((s32_t)((u32_t)(a) - (u32_t)(b)) > 0)
00096 #define TCP_SEQ_GEQ(a,b)    ((s32_t)((u32_t)(a) - (u32_t)(b)) >= 0)
00097 /* is b<=a<=c? */
00098 #if 0 /* see bug #10548 */
00099 #define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
00100 #endif
00101 #define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
00102 #define TCP_FIN 0x01U
00103 #define TCP_SYN 0x02U
00104 #define TCP_RST 0x04U
00105 #define TCP_PSH 0x08U
00106 #define TCP_ACK 0x10U
00107 #define TCP_URG 0x20U
00108 #define TCP_ECE 0x40U
00109 #define TCP_CWR 0x80U
00110 
00111 #define TCP_FLAGS 0x3fU
00112 
00113 /* Length of the TCP header, excluding options. */
00114 #define TCP_HLEN 20
00115 
00116 #ifndef TCP_TMR_INTERVAL
00117 #define TCP_TMR_INTERVAL       250  /* The TCP timer interval in milliseconds. */
00118 #endif /* TCP_TMR_INTERVAL */
00119 
00120 #ifndef TCP_FAST_INTERVAL
00121 #define TCP_FAST_INTERVAL      TCP_TMR_INTERVAL /* the fine grained timeout in milliseconds */
00122 #endif /* TCP_FAST_INTERVAL */
00123 
00124 #ifndef TCP_SLOW_INTERVAL
00125 #define TCP_SLOW_INTERVAL      (2*TCP_TMR_INTERVAL)  /* the coarse grained timeout in milliseconds */
00126 #endif /* TCP_SLOW_INTERVAL */
00127 
00128 #define TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */
00129 #define TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */
00130 
00131 #define TCP_OOSEQ_TIMEOUT        6U /* x RTO */
00132 
00133 #ifndef TCP_MSL
00134 #define TCP_MSL 60000UL /* The maximum segment lifetime in milliseconds */
00135 #endif
00136 
00137 /* Keepalive values, compliant with RFC 1122. Don't change this unless you know what you're doing */
00138 #ifndef  TCP_KEEPIDLE_DEFAULT
00139 #define  TCP_KEEPIDLE_DEFAULT     7200000UL /* Default KEEPALIVE timer in milliseconds */
00140 #endif
00141 
00142 #ifndef  TCP_KEEPINTVL_DEFAULT
00143 #define  TCP_KEEPINTVL_DEFAULT    75000UL   /* Default Time between KEEPALIVE probes in milliseconds */
00144 #endif
00145 
00146 #ifndef  TCP_KEEPCNT_DEFAULT
00147 #define  TCP_KEEPCNT_DEFAULT      9U        /* Default Counter for KEEPALIVE probes */
00148 #endif
00149 
00150 #define  TCP_MAXIDLE              TCP_KEEPCNT_DEFAULT * TCP_KEEPINTVL_DEFAULT  /* Maximum KEEPALIVE probe time */
00151 
00152 /* Fields are (of course) in network byte order.
00153  * Some fields are converted to host byte order in tcp_input().
00154  */
00155 #ifdef PACK_STRUCT_USE_INCLUDES
00156 #  include "arch/bpstruct.h"
00157 #endif
00158 PACK_STRUCT_BEGIN
00159 struct tcp_hdr {
00160   PACK_STRUCT_FIELD(u16_t src);
00161   PACK_STRUCT_FIELD(u16_t dest);
00162   PACK_STRUCT_FIELD(u32_t seqno);
00163   PACK_STRUCT_FIELD(u32_t ackno);
00164   PACK_STRUCT_FIELD(u16_t _hdrlen_rsvd_flags);
00165   PACK_STRUCT_FIELD(u16_t wnd);
00166   PACK_STRUCT_FIELD(u16_t chksum);
00167   PACK_STRUCT_FIELD(u16_t urgp);
00168 } PACK_STRUCT_STRUCT;
00169 PACK_STRUCT_END
00170 #ifdef PACK_STRUCT_USE_INCLUDES
00171 #  include "arch/epstruct.h"
00172 #endif
00173 
00174 #define TCPH_HDRLEN(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 12)
00175 #define TCPH_FLAGS(phdr)  (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)
00176 
00177 #define TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | TCPH_FLAGS(phdr))
00178 #define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = (((phdr)->_hdrlen_rsvd_flags & PP_HTONS((u16_t)(~(u16_t)(TCP_FLAGS)))) | htons(flags))
00179 #define TCPH_HDRLEN_FLAGS_SET(phdr, len, flags) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | (flags))
00180 
00181 #define TCPH_SET_FLAG(phdr, flags ) (phdr)->_hdrlen_rsvd_flags = ((phdr)->_hdrlen_rsvd_flags | htons(flags))
00182 #define TCPH_UNSET_FLAG(phdr, flags) (phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) | (TCPH_FLAGS(phdr) & ~(flags)) )
00183 
00184 #define TCP_TCPLEN(seg) ((seg)->len + ((TCPH_FLAGS((seg)->tcphdr) & (TCP_FIN | TCP_SYN)) != 0))
00185 
00186 /** Flags used on input processing, not on pcb->flags
00187 */
00188 #define TF_RESET     (u8_t)0x08U   /* Connection was reset. */
00189 #define TF_CLOSED    (u8_t)0x10U   /* Connection was sucessfully closed. */
00190 #define TF_GOT_FIN   (u8_t)0x20U   /* Connection was closed by the remote end. */
00191 
00192 
00193 #if LWIP_EVENT_API
00194 
00195 #define TCP_EVENT_ACCEPT(pcb,err,ret)    ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00196                 LWIP_EVENT_ACCEPT, NULL, 0, err)
00197 #define TCP_EVENT_SENT(pcb,space,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00198                    LWIP_EVENT_SENT, NULL, space, ERR_OK)
00199 #define TCP_EVENT_RECV(pcb,p,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00200                 LWIP_EVENT_RECV, (p), 0, (err))
00201 #define TCP_EVENT_CLOSED(pcb,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00202                 LWIP_EVENT_RECV, NULL, 0, ERR_OK)
00203 #define TCP_EVENT_CONNECTED(pcb,err,ret) ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00204                 LWIP_EVENT_CONNECTED, NULL, 0, (err))
00205 #define TCP_EVENT_POLL(pcb,ret)       ret = lwip_tcp_event((pcb)->callback_arg, (pcb),\
00206                 LWIP_EVENT_POLL, NULL, 0, ERR_OK)
00207 #define TCP_EVENT_ERR(errf,arg,err)  lwip_tcp_event((arg), NULL, \
00208                 LWIP_EVENT_ERR, NULL, 0, (err))
00209 
00210 #else /* LWIP_EVENT_API */
00211 
00212 #define TCP_EVENT_ACCEPT(pcb,err,ret)                          \
00213   do {                                                         \
00214     if((pcb)->accept != NULL)                                  \
00215       (ret) = (pcb)->accept((pcb)->callback_arg,(pcb),(err));  \
00216     else (ret) = ERR_ARG;                                      \
00217   } while (0)
00218 
00219 #define TCP_EVENT_SENT(pcb,space,ret)                          \
00220   do {                                                         \
00221     if((pcb)->sent != NULL)                                    \
00222       (ret) = (pcb)->sent((pcb)->callback_arg,(pcb),(space));  \
00223     else (ret) = ERR_OK;                                       \
00224   } while (0)
00225 
00226 #define TCP_EVENT_RECV(pcb,p,err,ret)                          \
00227   do {                                                         \
00228     if((pcb)->recv != NULL) {                                  \
00229       (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),(p),(err));\
00230     } else {                                                   \
00231       (ret) = tcp_recv_null(NULL, (pcb), (p), (err));          \
00232     }                                                          \
00233   } while (0)
00234 
00235 #define TCP_EVENT_CLOSED(pcb,ret)                                \
00236   do {                                                           \
00237     if(((pcb)->recv != NULL)) {                                  \
00238       (ret) = (pcb)->recv((pcb)->callback_arg,(pcb),NULL,ERR_OK);\
00239     } else {                                                     \
00240       (ret) = ERR_OK;                                            \
00241     }                                                            \
00242   } while (0)
00243 
00244 #define TCP_EVENT_CONNECTED(pcb,err,ret)                         \
00245   do {                                                           \
00246     if((pcb)->connected != NULL)                                 \
00247       (ret) = (pcb)->connected((pcb)->callback_arg,(pcb),(err)); \
00248     else (ret) = ERR_OK;                                         \
00249   } while (0)
00250 
00251 #define TCP_EVENT_POLL(pcb,ret)                                \
00252   do {                                                         \
00253     if((pcb)->poll != NULL)                                    \
00254       (ret) = (pcb)->poll((pcb)->callback_arg,(pcb));          \
00255     else (ret) = ERR_OK;                                       \
00256   } while (0)
00257 
00258 #define TCP_EVENT_ERR(errf,arg,err)                            \
00259   do {                                                         \
00260     if((errf) != NULL)                                         \
00261       (errf)((arg),(err));                                     \
00262   } while (0)
00263 
00264 #endif /* LWIP_EVENT_API */
00265 
00266 /** Enabled extra-check for TCP_OVERSIZE if LWIP_DEBUG is enabled */
00267 #if TCP_OVERSIZE && defined(LWIP_DEBUG)
00268 #define TCP_OVERSIZE_DBGCHECK 1
00269 #else
00270 #define TCP_OVERSIZE_DBGCHECK 0
00271 #endif
00272 
00273 /** Don't generate checksum on copy if CHECKSUM_GEN_TCP is disabled */
00274 #define TCP_CHECKSUM_ON_COPY  (LWIP_CHECKSUM_ON_COPY && CHECKSUM_GEN_TCP)
00275 
00276 /* This structure represents a TCP segment on the unsent, unacked and ooseq queues */
00277 struct tcp_seg {
00278   struct tcp_seg *next;    /* used when putting segements on a queue */
00279   struct pbuf *p;          /* buffer containing data + TCP header */
00280   u16_t len;               /* the TCP length of this segment */
00281 #if TCP_OVERSIZE_DBGCHECK
00282   u16_t oversize_left;     /* Extra bytes available at the end of the last
00283                               pbuf in unsent (used for asserting vs.
00284                               tcp_pcb.unsent_oversized only) */
00285 #endif /* TCP_OVERSIZE_DBGCHECK */ 
00286 #if TCP_CHECKSUM_ON_COPY
00287   u16_t chksum;
00288   u8_t  chksum_swapped;
00289 #endif /* TCP_CHECKSUM_ON_COPY */
00290   u8_t  flags;
00291 #define TF_SEG_OPTS_MSS         (u8_t)0x01U /* Include MSS option. */
00292 #define TF_SEG_OPTS_TS          (u8_t)0x02U /* Include timestamp option. */
00293 #define TF_SEG_DATA_CHECKSUMMED (u8_t)0x04U /* ALL data (not the header) is
00294                                                checksummed into 'chksum' */
00295   struct tcp_hdr *tcphdr;  /* the TCP header */
00296 };
00297 
00298 #define LWIP_TCP_OPT_LENGTH(flags)              \
00299   (flags & TF_SEG_OPTS_MSS ? 4  : 0) +          \
00300   (flags & TF_SEG_OPTS_TS  ? 12 : 0)
00301 
00302 /** This returns a TCP header option for MSS in an u32_t */
00303 #define TCP_BUILD_MSS_OPTION(mss) htonl(0x02040000 | ((mss) & 0xFFFF))
00304 
00305 /* Global variables: */
00306 extern struct tcp_pcb *tcp_input_pcb;
00307 extern u32_t tcp_ticks;
00308 extern u8_t tcp_active_pcbs_changed;
00309 
00310 /* The TCP PCB lists. */
00311 union tcp_listen_pcbs_t { /* List of all TCP PCBs in LISTEN state. */
00312   struct tcp_pcb_listen *listen_pcbs; 
00313   struct tcp_pcb *pcbs;
00314 };
00315 extern struct tcp_pcb *tcp_bound_pcbs;
00316 extern union tcp_listen_pcbs_t tcp_listen_pcbs;
00317 extern struct tcp_pcb *tcp_active_pcbs;  /* List of all TCP PCBs that are in a
00318               state in which they accept or send
00319               data. */
00320 extern struct tcp_pcb *tcp_tw_pcbs;      /* List of all TCP PCBs in TIME-WAIT. */
00321 
00322 extern struct tcp_pcb *tcp_tmp_pcb;      /* Only used for temporary storage. */
00323 
00324 /* Axioms about the above lists:   
00325    1) Every TCP PCB that is not CLOSED is in one of the lists.
00326    2) A PCB is only in one of the lists.
00327    3) All PCBs in the tcp_listen_pcbs list is in LISTEN state.
00328    4) All PCBs in the tcp_tw_pcbs list is in TIME-WAIT state.
00329 */
00330 /* Define two macros, TCP_REG and TCP_RMV that registers a TCP PCB
00331    with a PCB list or removes a PCB from a list, respectively. */
00332 #ifndef TCP_DEBUG_PCB_LISTS
00333 #define TCP_DEBUG_PCB_LISTS 0
00334 #endif
00335 #if TCP_DEBUG_PCB_LISTS
00336 #define TCP_REG(pcbs, npcb) do {\
00337                             LWIP_DEBUGF(TCP_DEBUG, ("TCP_REG %p local port %d\n", (npcb), (npcb)->local_port)); \
00338                             for(tcp_tmp_pcb = *(pcbs); \
00339           tcp_tmp_pcb != NULL; \
00340         tcp_tmp_pcb = tcp_tmp_pcb->next) { \
00341                                 LWIP_ASSERT("TCP_REG: already registered\n", tcp_tmp_pcb != (npcb)); \
00342                             } \
00343                             LWIP_ASSERT("TCP_REG: pcb->state != CLOSED", ((pcbs) == &tcp_bound_pcbs) || ((npcb)->state != CLOSED)); \
00344                             (npcb)->next = *(pcbs); \
00345                             LWIP_ASSERT("TCP_REG: npcb->next != npcb", (npcb)->next != (npcb)); \
00346                             *(pcbs) = (npcb); \
00347                             LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
00348               tcp_timer_needed(); \
00349                             } while(0)
00350 #define TCP_RMV(pcbs, npcb) do { \
00351                             LWIP_ASSERT("TCP_RMV: pcbs != NULL", *(pcbs) != NULL); \
00352                             LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removing %p from %p\n", (npcb), *(pcbs))); \
00353                             if(*(pcbs) == (npcb)) { \
00354                                *(pcbs) = (*pcbs)->next; \
00355                             } else for(tcp_tmp_pcb = *(pcbs); tcp_tmp_pcb != NULL; tcp_tmp_pcb = tcp_tmp_pcb->next) { \
00356                                if(tcp_tmp_pcb->next == (npcb)) { \
00357                                   tcp_tmp_pcb->next = (npcb)->next; \
00358                                   break; \
00359                                } \
00360                             } \
00361                             (npcb)->next = NULL; \
00362                             LWIP_ASSERT("TCP_RMV: tcp_pcbs sane", tcp_pcbs_sane()); \
00363                             LWIP_DEBUGF(TCP_DEBUG, ("TCP_RMV: removed %p from %p\n", (npcb), *(pcbs))); \
00364                             } while(0)
00365 
00366 #else /* LWIP_DEBUG */
00367 
00368 #define TCP_REG(pcbs, npcb)                        \
00369   do {                                             \
00370     (npcb)->next = *pcbs;                          \
00371     *(pcbs) = (npcb);                              \
00372     tcp_timer_needed();                            \
00373   } while (0)
00374 
00375 #define TCP_RMV(pcbs, npcb)                        \
00376   do {                                             \
00377     if(*(pcbs) == (npcb)) {                        \
00378       (*(pcbs)) = (*pcbs)->next;                   \
00379     }                                              \
00380     else {                                         \
00381       for(tcp_tmp_pcb = *pcbs;                     \
00382           tcp_tmp_pcb != NULL;                     \
00383           tcp_tmp_pcb = tcp_tmp_pcb->next) {       \
00384         if(tcp_tmp_pcb->next == (npcb)) {          \
00385           tcp_tmp_pcb->next = (npcb)->next;        \
00386           break;                                   \
00387         }                                          \
00388       }                                            \
00389     }                                              \
00390     (npcb)->next = NULL;                           \
00391   } while(0)
00392 
00393 #endif /* LWIP_DEBUG */
00394 
00395 #define TCP_REG_ACTIVE(npcb)                       \
00396   do {                                             \
00397     TCP_REG(&tcp_active_pcbs, npcb);               \
00398     tcp_active_pcbs_changed = 1;                   \
00399   } while (0)
00400 
00401 #define TCP_RMV_ACTIVE(npcb)                       \
00402   do {                                             \
00403     TCP_RMV(&tcp_active_pcbs, npcb);               \
00404     tcp_active_pcbs_changed = 1;                   \
00405   } while (0)
00406 
00407 #define TCP_PCB_REMOVE_ACTIVE(pcb)                 \
00408   do {                                             \
00409     tcp_pcb_remove(&tcp_active_pcbs, pcb);         \
00410     tcp_active_pcbs_changed = 1;                   \
00411   } while (0)
00412 
00413 
00414 /* Internal functions: */
00415 struct tcp_pcb *tcp_pcb_copy(struct tcp_pcb *pcb);
00416 void tcp_pcb_purge(struct tcp_pcb *pcb);
00417 void tcp_pcb_remove(struct tcp_pcb **pcblist, struct tcp_pcb *pcb);
00418 
00419 void tcp_segs_free(struct tcp_seg *seg);
00420 void tcp_seg_free(struct tcp_seg *seg);
00421 struct tcp_seg *tcp_seg_copy(struct tcp_seg *seg);
00422 
00423 #define tcp_ack(pcb)                               \
00424   do {                                             \
00425     if((pcb)->flags & TF_ACK_DELAY) {              \
00426       (pcb)->flags &= ~TF_ACK_DELAY;               \
00427       (pcb)->flags |= TF_ACK_NOW;                  \
00428     }                                              \
00429     else {                                         \
00430       (pcb)->flags |= TF_ACK_DELAY;                \
00431     }                                              \
00432   } while (0)
00433 
00434 #define tcp_ack_now(pcb)                           \
00435   do {                                             \
00436     (pcb)->flags |= TF_ACK_NOW;                    \
00437   } while (0)
00438 
00439 err_t tcp_send_fin(struct tcp_pcb *pcb);
00440 err_t tcp_enqueue_flags(struct tcp_pcb *pcb, u8_t flags);
00441 
00442 void tcp_rexmit_seg(struct tcp_pcb *pcb, struct tcp_seg *seg);
00443 
00444 void tcp_rst(u32_t seqno, u32_t ackno,
00445        ip_addr_t *local_ip, ip_addr_t *remote_ip,
00446        u16_t local_port, u16_t remote_port);
00447 
00448 u32_t tcp_next_iss(void);
00449 
00450 void tcp_keepalive(struct tcp_pcb *pcb);
00451 void tcp_zero_window_probe(struct tcp_pcb *pcb);
00452 
00453 #if TCP_CALCULATE_EFF_SEND_MSS
00454 u16_t tcp_eff_send_mss(u16_t sendmss, ip_addr_t *addr);
00455 #endif /* TCP_CALCULATE_EFF_SEND_MSS */
00456 
00457 #if LWIP_CALLBACK_API
00458 err_t tcp_recv_null(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err);
00459 #endif /* LWIP_CALLBACK_API */
00460 
00461 #if TCP_DEBUG || TCP_INPUT_DEBUG || TCP_OUTPUT_DEBUG
00462 void tcp_debug_print(struct tcp_hdr *tcphdr);
00463 void tcp_debug_print_flags(u8_t flags);
00464 void tcp_debug_print_state(enum tcp_state s);
00465 void tcp_debug_print_pcbs(void);
00466 s16_t tcp_pcbs_sane(void);
00467 #else
00468 #  define tcp_debug_print(tcphdr)
00469 #  define tcp_debug_print_flags(flags)
00470 #  define tcp_debug_print_state(s)
00471 #  define tcp_debug_print_pcbs()
00472 #  define tcp_pcbs_sane() 1
00473 #endif /* TCP_DEBUG */
00474 
00475 /** External function (implemented in timers.c), called when TCP detects
00476  * that a timer is needed (i.e. active- or time-wait-pcb found). */
00477 void tcp_timer_needed(void);
00478 
00479 
00480 #ifdef __cplusplus
00481 }
00482 #endif
00483 
00484 #endif /* LWIP_TCP */
00485 
00486 #endif /* __LWIP_TCP_H__ */