tcputil.c

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00001 /*
00002  * Copyright (C) 2001-2004 by egnite Software GmbH. All rights reserved.
00003  *
00004  * Redistribution and use in source and binary forms, with or without
00005  * modification, are permitted provided that the following conditions
00006  * are met:
00007  *
00008  * 1. Redistributions of source code must retain the above copyright
00009  *    notice, this list of conditions and the following disclaimer.
00010  * 2. Redistributions in binary form must reproduce the above copyright
00011  *    notice, this list of conditions and the following disclaimer in the
00012  *    documentation and/or other materials provided with the distribution.
00013  * 3. Neither the name of the copyright holders nor the names of
00014  *    contributors may be used to endorse or promote products derived
00015  *    from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY EGNITE SOFTWARE GMBH AND CONTRIBUTORS
00018  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
00019  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
00020  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL EGNITE
00021  * SOFTWARE GMBH OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
00022  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
00023  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
00024  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
00025  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
00026  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
00027  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
00028  * SUCH DAMAGE.
00029  *
00030  * For additional information see http://www.ethernut.de/
00031  *
00032  */
00033 
00034 /*
00035  * $Log: tcputil.c,v $
00036  * Revision 1.3  2008/07/27 11:43:22  haraldkipp
00037  * Configurable TCP retransmissions.
00038  *
00039  * Revision 1.2  2004/07/30 19:54:46  drsung
00040  * Some code of TCP stack redesigned. Round trip time calculation is now
00041  * supported. Fixed several bugs in TCP state machine. Now TCP connections
00042  * should be more reliable under heavy traffic or poor physical connections.
00043  *
00044  * Revision 1.1.1.1  2003/05/09 14:41:45  haraldkipp
00045  * Initial using 3.2.1
00046  *
00047  * Revision 1.10  2003/05/06 18:23:15  harald
00048  * Still not done
00049  *
00050  * Revision 1.9  2003/02/04 18:14:57  harald
00051  * Version 3 released
00052  *
00053  * Revision 1.8  2002/06/26 17:29:36  harald
00054  * First pre-release with 2.4 stack
00055  *
00056  */
00057 
00058 #include <cfg/tcp.h>
00059 
00060 #include <netinet/tcputil.h>
00061 #include <sys/timer.h>
00062 #include <stdio.h>
00063 
00068 
00069 /* Limit retransmission timeout to 200ms as lower and 20secs as upper boundary */
00070 #ifndef TCP_RTTO_MIN
00071 #define TCP_RTTO_MIN    200
00072 #endif
00073 #ifndef TCP_RTTO_MAX
00074 #define TCP_RTTO_MAX    20000
00075 #endif
00076 
00083 int IsInLimits(u_long x, u_long low, u_long high)
00084 {
00085     if (low <= high) {
00086         if (low <= x && x <= high)
00087             return 1;
00088     } else if (low >= x && x >= high)
00089         return 1;
00090 
00091     return 0;
00092 }
00093 
00094 #define min(a,b) ((a>b)?b:a)
00095 #define max(a,b) ((a>b)?a:b)
00096 
00097 /*
00098  * Calculate round trip time.
00099  */
00100 void NutTcpCalcRtt(TCPSOCKET * sock)
00101 {
00102     u_short delta;
00103     
00104     if (sock->so_retran_time == 0)
00105         return;
00106         
00107     delta = (u_short) NutGetMillis() - sock->so_retran_time;
00108     
00109     /* According to RFC793 (or STD007), page 41, we use 0.8 for ALPHA and 2.0 for BETA. */
00110     sock->so_rtto = min (TCP_RTTO_MAX, max(TCP_RTTO_MIN, (delta * 4 + sock->so_rtto * 8) / 10));
00111     //@@@printf ("[%04X] new retran timeout: %u, delta: %u\n", (u_short) sock, sock->so_rtto, delta);
00112 }
00113 

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