tcp.h

FreeRTOS is a portable, open source, mini Real Time Kernel - a free to download and royalty free RTO

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved. 
 * 
 * Redistribution and use in source and binary forms, with or without modification, 
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED 
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT 
 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY 
 * OF SUCH DAMAGE.
 *
 * This file is part of the lwIP TCP/IP stack.
 * 
 * Author: Adam Dunkels <[e-mail]>
 *
 */
#ifndef __LWIP_TCP_H__
#define __LWIP_TCP_H__

#include "lwip/sys.h"
#include "lwip/mem.h"

#include "lwip/pbuf.h"
#include "lwip/opt.h"
#include "lwip/ip.h"
#include "lwip/icmp.h"

#include "lwip/err.h"

struct tcp_pcb;

/* Functions for interfacing with TCP: */

/* Lower layer interface to TCP: */
void             tcp_init    (void);  /* Must be called first to
           initialize TCP. */
void             tcp_tmr     (void);  /* Must be called every
           TCP_TMR_INTERVAL
           ms. (Typically 250 ms). */
/* Application program's interface: */
struct tcp_pcb * tcp_new     (void);
struct tcp_pcb * tcp_alloc   (u8_t prio);

void             tcp_arg     (struct tcp_pcb *pcb, void *arg);
void             tcp_accept  (struct tcp_pcb *pcb,
            err_t (* accept)(void *arg, struct tcp_pcb *newpcb,
                 err_t err));
void             tcp_recv    (struct tcp_pcb *pcb,
            err_t (* recv)(void *arg, struct tcp_pcb *tpcb,
          struct pbuf *p, err_t err));
void             tcp_sent    (struct tcp_pcb *pcb,
            err_t (* sent)(void *arg, struct tcp_pcb *tpcb,
               u16_t len));
void             tcp_poll    (struct tcp_pcb *pcb,
            err_t (* poll)(void *arg, struct tcp_pcb *tpcb),
            u8_t interval);
void             tcp_err     (struct tcp_pcb *pcb,
            void (* err)(void *arg, err_t err));

#define          tcp_mss(pcb)      ((pcb)->mss)
#define          tcp_sndbuf(pcb)   ((pcb)->snd_buf)

void             tcp_recved  (struct tcp_pcb *pcb, u16_t len);
err_t            tcp_bind    (struct tcp_pcb *pcb, struct ip_addr *ipaddr,
            u16_t port);
err_t            tcp_connect (struct tcp_pcb *pcb, struct ip_addr *ipaddr,
            u16_t port, err_t (* connected)(void *arg,
                    struct tcp_pcb *tpcb,
                    err_t err));
struct tcp_pcb * tcp_listen  (struct tcp_pcb *pcb);
void             tcp_abort   (struct tcp_pcb *pcb);
err_t            tcp_close   (struct tcp_pcb *pcb);
err_t            tcp_write   (struct tcp_pcb *pcb, const void *dataptr, u16_t len,
            u8_t copy);

void             tcp_setprio (struct tcp_pcb *pcb, u8_t prio);

#define TCP_PRIO_MIN    1
#define TCP_PRIO_NORMAL 64
#define TCP_PRIO_MAX    127

/* It is also possible to call these two functions at the right
   intervals (instead of calling tcp_tmr()). */
void             tcp_slowtmr (void);
void             tcp_fasttmr (void);


/* Only used by IP to pass a TCP segment to TCP: */
void             tcp_input   (struct pbuf *p, struct netif *inp);
/* Used within the TCP code only: */
err_t            tcp_output  (struct tcp_pcb *pcb);
void             tcp_rexmit  (struct tcp_pcb *pcb);
void             tcp_rexmit_rto  (struct tcp_pcb *pcb);



#define TCP_SEQ_LT(a,b)     ((s32_t)((a)-(b)) < 0)
#define TCP_SEQ_LEQ(a,b)    ((s32_t)((a)-(b)) <= 0)
#define TCP_SEQ_GT(a,b)     ((s32_t)((a)-(b)) > 0)
#define TCP_SEQ_GEQ(a,b)    ((s32_t)((a)-(b)) >= 0)
/* is b<=a<=c? */
#if 0 /* see bug #10548 */
#define TCP_SEQ_BETWEEN(a,b,c) ((c)-(b) >= (a)-(b))
#endif
#define TCP_SEQ_BETWEEN(a,b,c) (TCP_SEQ_GEQ(a,b) && TCP_SEQ_LEQ(a,c))
#define TCP_FIN 0x01U
#define TCP_SYN 0x02U
#define TCP_RST 0x04U
#define TCP_PSH 0x08U
#define TCP_ACK 0x10U
#define TCP_URG 0x20U
#define TCP_ECE 0x40U
#define TCP_CWR 0x80U

#define TCP_FLAGS 0x3fU

/* Length of the TCP header, excluding options. */
#define TCP_HLEN 20

#ifndef TCP_TMR_INTERVAL
#define TCP_TMR_INTERVAL       250  /* The TCP timer interval in
                                       milliseconds. */
#endif /* TCP_TMR_INTERVAL */

#ifndef TCP_FAST_INTERVAL
#define TCP_FAST_INTERVAL      TCP_TMR_INTERVAL /* the fine grained timeout in
                                       milliseconds */
#endif /* TCP_FAST_INTERVAL */

#ifndef TCP_SLOW_INTERVAL
#define TCP_SLOW_INTERVAL      (2*TCP_TMR_INTERVAL)  /* the coarse grained timeout in
                                       milliseconds */
#endif /* TCP_SLOW_INTERVAL */

#define TCP_FIN_WAIT_TIMEOUT 20000 /* milliseconds */
#define TCP_SYN_RCVD_TIMEOUT 20000 /* milliseconds */

#define TCP_OOSEQ_TIMEOUT        6 /* x RTO */

#define TCP_MSL 60000  /* The maximum segment lifetime in microseconds */

/*
 * User-settable options (used with setsockopt).
 */
#define	TCP_NODELAY	   0x01	   /* don't delay send to coalesce packets */
#define TCP_KEEPALIVE  0x02    /* send KEEPALIVE probes when idle for pcb->keepalive miliseconds */

/* Keepalive values */
#define  TCP_KEEPDEFAULT   7200000                       /* KEEPALIVE timer in miliseconds */
#define  TCP_KEEPINTVL     75000                         /* Time between KEEPALIVE probes in miliseconds */
#define  TCP_KEEPCNT       9                             /* Counter for KEEPALIVE probes */
#define  TCP_MAXIDLE       TCP_KEEPCNT * TCP_KEEPINTVL   /* Maximum KEEPALIVE probe time */


#ifdef PACK_STRUCT_USE_INCLUDES
#  include "arch/bpstruct.h"
#endif
PACK_STRUCT_BEGIN
struct tcp_hdr {
  PACK_STRUCT_FIELD(u16_t src);
  PACK_STRUCT_FIELD(u16_t dest);
  PACK_STRUCT_FIELD(u32_t seqno);
  PACK_STRUCT_FIELD(u32_t ackno);
  PACK_STRUCT_FIELD(u16_t _hdrlen_rsvd_flags);
  PACK_STRUCT_FIELD(u16_t wnd);
  PACK_STRUCT_FIELD(u16_t chksum);
  PACK_STRUCT_FIELD(u16_t urgp);
} PACK_STRUCT_STRUCT;
PACK_STRUCT_END
#ifdef PACK_STRUCT_USE_INCLUDES
#  include "arch/epstruct.h"
#endif

#define TCPH_OFFSET(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 8)
#define TCPH_HDRLEN(phdr) (ntohs((phdr)->_hdrlen_rsvd_flags) >> 12)
#define TCPH_FLAGS(phdr)  (ntohs((phdr)->_hdrlen_rsvd_flags) & TCP_FLAGS)

#define TCPH_OFFSET_SET(phdr, offset) (phdr)->_hdrlen_rsvd_flags = htons(((offset) << 8) | TCPH_FLAGS(phdr))
#define TCPH_HDRLEN_SET(phdr, len) (phdr)->_hdrlen_rsvd_flags = htons(((len) << 12) | TCPH_FLAGS(phdr))
#define TCPH_FLAGS_SET(phdr, flags) (phdr)->_hdrlen_rsvd_flags = htons((ntohs((phdr)->_hdrlen_rsvd_flags) & ~TCP_FLAGS) | (flags))
#define TCPH_SET_FLAG(phdr, flags ) (phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) | (flags))
#define TCPH_UNSET_FLAG(phdr, flags) (phdr)->_hdrlen_rsvd_flags = htons(ntohs((phdr)->_hdrlen_rsvd_flags) | (TCPH_FLAGS(phdr) & ~(flags)) )

#define TCP_TCPLEN(seg) ((seg)->len + ((TCPH_FLAGS((seg)->tcphdr) & TCP_FIN || \
          TCPH_FLAGS((seg)->tcphdr) & TCP_SYN)? 1: 0))

enum tcp_state {
  CLOSED      = 0,
  LISTEN      = 1,
  SYN_SENT    = 2,
  SYN_RCVD    = 3,
  ESTABLISHED = 4,
  FIN_WAIT_1  = 5,
  FIN_WAIT_2  = 6,
  CLOSE_WAIT  = 7,
  CLOSING     = 8,
  LAST_ACK    = 9,
  TIME_WAIT   = 10
};

/* the TCP protocol control block */
struct tcp_pcb {
/** common PCB members */
  IP_PCB;
/** protocol specific PCB members */
  struct tcp_pcb *next; /* for the linked list */
  enum tcp_state state; /* TCP state */
  u8_t prio;
  void *callback_arg;

  u16_t local_port;
  u16_t remote_port;
  
  u8_t flags;
#define TF_ACK_DELAY (u8_t)0x01U   /* Delayed ACK. */
#define TF_ACK_NOW   (u8_t)0x02U   /* Immediate ACK. */
#define TF_INFR      (u8_t)0x04U   /* In fast recovery. */
#define TF_RESET     (u8_t)0x08U   /* Connection was reset. */
#define TF_CLOSED    (u8_t)0x10U   /* Connection was sucessfully closed. */
#define TF_GOT_FIN   (u8_t)0x20U   /* Connection was closed by the remote end. */
#define TF_NODELAY   (u8_t)0x40U   /* Disable Nagle algorithm */

  /* receiver variables */
  u32_t rcv_nxt;   /* next seqno expected */
  u16_t rcv_wnd;   /* receiver window */
  
  /* Timers */
  u32_t tmr;
  u8_t polltmr, pollinterval;
  
  /* Retransmission timer. */
  u16_t rtime;
  
  u16_t mss;   /* maximum segment size */
  
  /* RTT (round trip time) estimation variables */
  u32_t rttest; /* RTT estimate in 500ms ticks */
  u32_t rtseq;  /* sequence number being timed */
  s16_t sa, sv; /* @todo document this */

  u16_t rto;    /* retransmission time-out */
  u8_t nrtx;    /* number of retransmissions */

  /* fast retransmit/recovery */
  u32_t lastack; /* Highest acknowledged seqno. */
  u8_t dupacks;
  
  /* congestion avoidance/control variables */
  u16_t cwnd;  
  u16_t ssthresh;