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uip-split.c
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uip-split.c
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/*
* Copyright (c) 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. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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 INSTITUTE OR CONTRIBUTORS 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 uIP TCP/IP stack
*
* Author: Adam Dunkels <adam@sics.se>
*
* $Id: uip-split.c,v 1.2 2006/06/12 08:00:30 adam Exp $
*/
#include <string.h>
#include "uip-split.h"
#include "uip.h"
#include "uip-fw.h"
#include "uip_arch.h"
#define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
/*-----------------------------------------------------------------------------*/
void
uip_split_output(void)
{
u16_t tcplen, len1, len2;
/* We only try to split maximum sized TCP segments. */
if(BUF->proto == UIP_PROTO_TCP &&
uip_len == UIP_BUFSIZE - UIP_LLH_LEN) {
tcplen = uip_len - UIP_TCPIP_HLEN;
/* Split the segment in two. If the original packet length was
odd, we make the second packet one byte larger. */
len1 = len2 = tcplen / 2;
if(len1 + len2 < tcplen) {
++len2;
}
/* Create the first packet. This is done by altering the length
field of the IP header and updating the checksums. */
uip_len = len1 + UIP_TCPIP_HLEN;
#if UIP_CONF_IPV6
/* For IPv6, the IP length field does not include the IPv6 IP header
length. */
BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
#else /* UIP_CONF_IPV6 */
BUF->len[0] = uip_len >> 8;
BUF->len[1] = uip_len & 0xff;
#endif /* UIP_CONF_IPV6 */
/* Recalculate the TCP checksum. */
BUF->tcpchksum = 0;
BUF->tcpchksum = ~(uip_tcpchksum());
#if !UIP_CONF_IPV6
/* Recalculate the IP checksum. */
BUF->ipchksum = 0;
BUF->ipchksum = ~(uip_ipchksum());
#endif /* UIP_CONF_IPV6 */
/* Transmit the first packet. */
uip_fw_output();
/*tcpip_output();*/
/* Now, create the second packet. To do this, it is not enough to
just alter the length field, but we must also update the TCP
sequence number and point the uip_appdata to a new place in
memory. This place is detemined by the length of the first
packet (len1). */
uip_len = len2 + UIP_TCPIP_HLEN;
#if UIP_CONF_IPV6
/* For IPv6, the IP length field does not include the IPv6 IP header
length. */
BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
#else /* UIP_CONF_IPV6 */
BUF->len[0] = uip_len >> 8;
BUF->len[1] = uip_len & 0xff;
#endif /* UIP_CONF_IPV6 */
/* uip_appdata += len1;*/
memcpy(uip_appdata, (u8_t *)uip_appdata + len1, len2);
uip_add32(BUF->seqno, len1);
BUF->seqno[0] = uip_acc32[0];
BUF->seqno[1] = uip_acc32[1];
BUF->seqno[2] = uip_acc32[2];
BUF->seqno[3] = uip_acc32[3];
/* Recalculate the TCP checksum. */
BUF->tcpchksum = 0;
BUF->tcpchksum = ~(uip_tcpchksum());
#if !UIP_CONF_IPV6
/* Recalculate the IP checksum. */
BUF->ipchksum = 0;
BUF->ipchksum = ~(uip_ipchksum());
#endif /* UIP_CONF_IPV6 */
/* Transmit the second packet. */
uip_fw_output();
/*tcpip_output();*/
} else {
uip_fw_output();
/*tcpip_output();*/
}
}
/*-----------------------------------------------------------------------------*/