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jeremybenn |
/*
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* Copyright (c) 2004, Swedish Institute of Computer Science.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the uIP TCP/IP stack
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*
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* Author: Adam Dunkels <adam@sics.se>
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*
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* $Id: uip-split.c 2 2011-07-17 20:13:17Z filepang@gmail.com $
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*/
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#include <string.h>
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#include "uip-split.h"
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#include "uip.h"
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#include "uip-fw.h"
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#include "uip_arch.h"
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#define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
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/*-----------------------------------------------------------------------------*/
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void
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uip_split_output(void)
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{
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u16_t tcplen, len1, len2;
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/* We only try to split maximum sized TCP segments. */
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if(BUF->proto == UIP_PROTO_TCP &&
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uip_len == UIP_BUFSIZE - UIP_LLH_LEN) {
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tcplen = uip_len - UIP_TCPIP_HLEN;
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/* Split the segment in two. If the original packet length was
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odd, we make the second packet one byte larger. */
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len1 = len2 = tcplen / 2;
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if(len1 + len2 < tcplen) {
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++len2;
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}
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/* Create the first packet. This is done by altering the length
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field of the IP header and updating the checksums. */
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uip_len = len1 + UIP_TCPIP_HLEN;
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#if UIP_CONF_IPV6
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/* For IPv6, the IP length field does not include the IPv6 IP header
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length. */
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BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
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BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
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#else /* UIP_CONF_IPV6 */
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BUF->len[0] = uip_len >> 8;
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BUF->len[1] = uip_len & 0xff;
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#endif /* UIP_CONF_IPV6 */
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/* Recalculate the TCP checksum. */
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BUF->tcpchksum = 0;
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BUF->tcpchksum = ~(uip_tcpchksum());
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#if !UIP_CONF_IPV6
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/* Recalculate the IP checksum. */
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BUF->ipchksum = 0;
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BUF->ipchksum = ~(uip_ipchksum());
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#endif /* UIP_CONF_IPV6 */
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/* Transmit the first packet. */
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/* uip_fw_output();*/
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tcpip_output();
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/* Now, create the second packet. To do this, it is not enough to
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just alter the length field, but we must also update the TCP
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sequence number and point the uip_appdata to a new place in
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memory. This place is detemined by the length of the first
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packet (len1). */
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uip_len = len2 + UIP_TCPIP_HLEN;
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#if UIP_CONF_IPV6
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/* For IPv6, the IP length field does not include the IPv6 IP header
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length. */
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BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
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BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
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#else /* UIP_CONF_IPV6 */
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BUF->len[0] = uip_len >> 8;
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BUF->len[1] = uip_len & 0xff;
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#endif /* UIP_CONF_IPV6 */
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/* uip_appdata += len1;*/
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memcpy(uip_appdata, (u8_t *)uip_appdata + len1, len2);
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uip_add32(BUF->seqno, len1);
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BUF->seqno[0] = uip_acc32[0];
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BUF->seqno[1] = uip_acc32[1];
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BUF->seqno[2] = uip_acc32[2];
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BUF->seqno[3] = uip_acc32[3];
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/* Recalculate the TCP checksum. */
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BUF->tcpchksum = 0;
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BUF->tcpchksum = ~(uip_tcpchksum());
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#if !UIP_CONF_IPV6
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/* Recalculate the IP checksum. */
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BUF->ipchksum = 0;
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BUF->ipchksum = ~(uip_ipchksum());
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#endif /* UIP_CONF_IPV6 */
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/* Transmit the second packet. */
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/* uip_fw_output();*/
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tcpip_output();
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} else {
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/* uip_fw_output();*/
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tcpip_output();
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}
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}
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/*-----------------------------------------------------------------------------*/
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