tcpin.c

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/*
 * Copyright (C) 2001-2003 by egnite Software GmbH. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
 * 1. Redistributions of source code must retain the above copyright
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    documentation and/or other materials provided with the distribution.
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 * For additional information see http://www.ethernut.de/
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 * -
 * Portions Copyright (C) 2000 David J. Hudson <dave@humbug.demon.co.uk>
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 *  The Regents of the University of California.  All rights reserved.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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 */

/*
 * $Log$
 * Revision 1.5  2008/10/05 16:48:52  haraldkipp
 * Security fix. Check various lengths of incoming packets.
 *
 * Revision 1.4  2008/08/20 06:57:00  haraldkipp
 * Implemented IP demultiplexer.
 *
 * Revision 1.3  2008/08/11 07:00:32  haraldkipp
 * BSD types replaced by stdint types (feature request #1282721).
 *
 * Revision 1.2  2005/04/30 16:42:42  chaac
 * Fixed bug in handling of NUTDEBUG. Added include for cfg/os.h. If NUTDEBUG
 * is defined in NutConf, it will make effect where it is used.
 *
 * Revision 1.1.1.1  2003/05/09 14:41:39  haraldkipp
 * Initial using 3.2.1
 *
 * Revision 1.11  2003/02/04 18:14:57  harald
 * Version 3 released
 *
 * Revision 1.10  2002/06/26 17:29:36  harald
 * First pre-release with 2.4 stack
 *
 */

#include <cfg/os.h>
#include <sys/thread.h>

#include <netinet/ip.h>
#include <sys/socket.h>
#include <netinet/tcp.h>

#ifdef NUTDEBUG
#include <net/netdebug.h>
#endif



int NutTcpInput(NUTDEVICE * dev, NETBUF * nb)
{
    TCPHDR *th = (TCPHDR *) nb->nb_tp.vp;

    /* Process unicasts only. */
    if (th && (nb->nb_flags & NBAF_UNICAST) != 0) {
        uint_fast8_t hdrlen = th->th_off * 4;

        /* Check the header length. */
        if (hdrlen >= sizeof(TCPHDR) && hdrlen <= nb->nb_tp.sz) {
            nb->nb_ap.sz = nb->nb_tp.sz - hdrlen;
            if (nb->nb_ap.sz) {
                nb->nb_ap.vp = ((uint32_t *) th) + th->th_off;
            }
            nb->nb_tp.sz = hdrlen;

            /*
            ** According to RFC1122 we MUST check the checksum
            ** on incoming segments. Anyway, we rely on lower
            ** level checksums to save processing resources.
            **
            ** However, we may combine checksum calculation
            ** with moving data to the receiver buffer.
            **/

            NutTcpStateMachine(nb);

            return 0;
        }
    }
    /* Silently discard this segment. */
    NutNetBufFree(nb);

    return 0;
}