Projects/Webserver/Lib/uip/uip-split.c

   1 /*
   2  * Copyright (c) 2004, Swedish Institute of Computer Science.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the Institute nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * This file is part of the Contiki operating system.
  30  *
  31  * Author: Adam Dunkels <adam@sics.se>
  32  *
  33  * $Id: uip-split.c,v 1.2 2008/10/14 13:39:12 julienabeille Exp $
  34  */
  35
  36 #include "uip-split.h"
  37
  38
  39 #define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
  40
  41 /*-----------------------------------------------------------------------------*/
  42 void
  43 uip_split_output(void)
  44 {
  45 #if UIP_TCP
  46   u16_t tcplen, len1, len2;
  47
  48   /* We only try to split maximum sized TCP segments. */
  49   if(BUF->proto == UIP_PROTO_TCP  && uip_len == UIP_BUFSIZE) {
  50
  51     tcplen = uip_len - UIP_TCPIP_HLEN - UIP_LLH_LEN;
  52     /* Split the segment in two. If the original packet length was
  53        odd, we make the second packet one byte larger. */
  54     len1 = len2 = tcplen / 2;
  55     if(len1 + len2 < tcplen) {
  56       ++len2;
  57     }
  58
  59     /* Create the first packet. This is done by altering the length
  60        field of the IP header and updating the checksums. */
  61     uip_len = len1 + UIP_TCPIP_HLEN + UIP_LLH_LEN;
  62 #if UIP_CONF_IPV6
  63     /* For IPv6, the IP length field does not include the IPv6 IP header
  64        length. */
  65     BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
  66     BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
  67 #else /* UIP_CONF_IPV6 */
  68     BUF->len[0] = (uip_len - UIP_LLH_LEN) >> 8;
  69     BUF->len[1] = (uip_len - UIP_LLH_LEN) & 0xff;
  70 #endif /* UIP_CONF_IPV6 */
  71
  72     /* Recalculate the TCP checksum. */
  73     BUF->tcpchksum = 0;
  74     BUF->tcpchksum = ~(uip_tcpchksum());
  75
  76 #if !UIP_CONF_IPV6
  77     /* Recalculate the IP checksum. */
  78     BUF->ipchksum = 0;
  79     BUF->ipchksum = ~(uip_ipchksum());
  80 #endif /* UIP_CONF_IPV6 */
  81
  82     /* Transmit the first packet. */
  83 #if UIP_CONF_IPV6
  84     tcpip_ipv6_output();
  85 #else
  86         RNDIS_Host_SendPacket(&Ethernet_RNDIS_Interface, uip_buf, uip_len);
  87 #endif /* UIP_CONF_IPV6 */
  88
  89     /* Now, create the second packet. To do this, it is not enough to
  90        just alter the length field, but we must also update the TCP
  91        sequence number and point the uip_appdata to a new place in
  92        memory. This place is determined by the length of the first
  93        packet (len1). */
  94     uip_len = len2 + UIP_TCPIP_HLEN + UIP_LLH_LEN;
  95 #if UIP_CONF_IPV6
  96     /* For IPv6, the IP length field does not include the IPv6 IP header
  97        length. */
  98     BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
  99     BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
 100 #else /* UIP_CONF_IPV6 */
 101     BUF->len[0] = (uip_len  - UIP_LLH_LEN) >> 8;
 102     BUF->len[1] = (uip_len - UIP_LLH_LEN) & 0xff;
 103 #endif /* UIP_CONF_IPV6 */
 104
 105     memcpy(uip_appdata, (u8_t *)uip_appdata + len1, len2);
 106
 107     uip_add32(BUF->seqno, len1);
 108     BUF->seqno[0] = uip_acc32[0];
 109     BUF->seqno[1] = uip_acc32[1];
 110     BUF->seqno[2] = uip_acc32[2];
 111     BUF->seqno[3] = uip_acc32[3];
 112
 113     /* Recalculate the TCP checksum. */
 114     BUF->tcpchksum = 0;
 115     BUF->tcpchksum = ~(uip_tcpchksum());
 116
 117 #if !UIP_CONF_IPV6
 118     /* Recalculate the IP checksum. */
 119     BUF->ipchksum = 0;
 120     BUF->ipchksum = ~(uip_ipchksum());
 121 #endif /* UIP_CONF_IPV6 */
 122
 123     /* Transmit the second packet. */
 124 #if UIP_CONF_IPV6
 125     tcpip_ipv6_output();
 126 #else
 127         RNDIS_Host_SendPacket(&Ethernet_RNDIS_Interface, uip_buf, uip_len);
 128 #endif /* UIP_CONF_IPV6 */
 129     return;
 130   }
 131 #endif /* UIP_TCP */
 132
 133   /*    uip_fw_output();*/
 134 #if UIP_CONF_IPV6
 135         tcpip_ipv6_output();
 136 #else
 137         RNDIS_Host_SendPacket(&Ethernet_RNDIS_Interface, uip_buf, uip_len);
 138 #endif /* UIP_CONF_IPV6 */
 139 }
 140
 141 /*-----------------------------------------------------------------------------*/