| /* |
| * 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 Contiki operating system. |
| * |
| * Author: Adam Dunkels <adam@sics.se> |
| * |
| * $Id: uip-split.c,v 1.3 2004/09/12 20:24:56 adamdunkels Exp $ |
| */ |
| |
| #include "uip-split.h" |
| #include "uip.h" |
| #include "uip-fw.h" |
| #include "uip_arch.h" |
| |
| #include "tcpip.h" |
| |
| #define BUF ((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; |
| BUF->len[0] = (uip_len >> 8); |
| BUF->len[1] = (uip_len & 0xff); |
| |
| /* Recalculate the TCP checksum. */ |
| BUF->tcpchksum = 0; |
| BUF->tcpchksum = ~(uip_tcpchksum()); |
| |
| /* Recalculate the IP checksum. */ |
| BUF->ipchksum = 0; |
| BUF->ipchksum = ~(uip_ipchksum()); |
| |
| /* 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; |
| BUF->len[0] = (uip_len >> 8); |
| BUF->len[1] = (uip_len & 0xff); |
| |
| uip_appdata += len1; |
| |
| 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()); |
| |
| /* Recalculate the IP checksum. */ |
| BUF->ipchksum = 0; |
| BUF->ipchksum = ~(uip_ipchksum()); |
| |
| /* Transmit the second packet. */ |
| /* uip_fw_output();*/ |
| tcpip_output(); |
| } else { |
| /* uip_fw_output();*/ |
| tcpip_output(); |
| } |
| |
| } |
| /*-----------------------------------------------------------------------------*/ |