uIP 1.0: uip/uip-split.c Source File

00001 /*
+00002  * Copyright (c) 2004, Swedish Institute of Computer Science.
+00003  * All rights reserved.
+00004  *
+00005  * Redistribution and use in source and binary forms, with or without
+00006  * modification, are permitted provided that the following conditions
+00007  * are met:
+00008  * 1. Redistributions of source code must retain the above copyright
+00009  *    notice, this list of conditions and the following disclaimer.
+00010  * 2. Redistributions in binary form must reproduce the above copyright
+00011  *    notice, this list of conditions and the following disclaimer in the
+00012  *    documentation and/or other materials provided with the distribution.
+00013  * 3. Neither the name of the Institute nor the names of its contributors
+00014  *    may be used to endorse or promote products derived from this software
+00015  *    without specific prior written permission.
+00016  *
+00017  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+00018  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+00020  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+00021  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+00022  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+00023  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+00024  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+00025  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+00026  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+00027  * SUCH DAMAGE.
+00028  *
+00029  * This file is part of the uIP TCP/IP stack
+00030  *
+00031  * Author: Adam Dunkels <adam@sics.se>
+00032  *
+00033  * $Id: uip-split.c,v 1.2 2006/06/12 08:00:30 adam Exp $
+00034  */
+00035 
+00036 #include <string.h>
+00037 
+00038 #include "uip-split.h"
+00039 #include "uip.h"
+00040 #include "uip-fw.h"
+00041 #include "uip_arch.h"
+00042 
+00043 
+00044 
+00045 #define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
+00046 
+00047 /*-----------------------------------------------------------------------------*/
+00048 void
+00049 uip_split_output(void)
+00050 {
+00051   u16_t tcplen, len1, len2;
+00052 
+00053   /* We only try to split maximum sized TCP segments. */
+00054   if(BUF->proto == UIP_PROTO_TCP &&
+00055      uip_len == UIP_BUFSIZE - UIP_LLH_LEN) {
+00056 
+00057     tcplen = uip_len - UIP_TCPIP_HLEN;
+00058     /* Split the segment in two. If the original packet length was
+00059        odd, we make the second packet one byte larger. */
+00060     len1 = len2 = tcplen / 2;
+00061     if(len1 + len2 < tcplen) {
+00062       ++len2;
+00063     }
+00064 
+00065     /* Create the first packet. This is done by altering the length
+00066        field of the IP header and updating the checksums. */
+00067     uip_len = len1 + UIP_TCPIP_HLEN;
+00068 #if UIP_CONF_IPV6
+00069     /* For IPv6, the IP length field does not include the IPv6 IP header
+00070        length. */
+00071     BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
+00072     BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
+00073 #else /* UIP_CONF_IPV6 */
+00074     BUF->len[0] = uip_len >> 8;
+00075     BUF->len[1] = uip_len & 0xff;
+00076 #endif /* UIP_CONF_IPV6 */
+00077     
+00078     /* Recalculate the TCP checksum. */
+00079     BUF->tcpchksum = 0;
+00080     BUF->tcpchksum = ~(uip_tcpchksum());
+00081 
+00082 #if !UIP_CONF_IPV6
+00083     /* Recalculate the IP checksum. */
+00084     BUF->ipchksum = 0;
+00085     BUF->ipchksum = ~(uip_ipchksum());
+00086 #endif /* UIP_CONF_IPV6 */
+00087     
+00088     /* Transmit the first packet. */
+00089     /*    uip_fw_output();*/
+00090     tcpip_output();
+00091 
+00092     /* Now, create the second packet. To do this, it is not enough to
+00093        just alter the length field, but we must also update the TCP
+00094        sequence number and point the uip_appdata to a new place in
+00095        memory. This place is detemined by the length of the first
+00096        packet (len1). */
+00097     uip_len = len2 + UIP_TCPIP_HLEN;
+00098 #if UIP_CONF_IPV6
+00099     /* For IPv6, the IP length field does not include the IPv6 IP header
+00100        length. */
+00101     BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
+00102     BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
+00103 #else /* UIP_CONF_IPV6 */
+00104     BUF->len[0] = uip_len >> 8;
+00105     BUF->len[1] = uip_len & 0xff;
+00106 #endif /* UIP_CONF_IPV6 */
+00107     
+00108     /*    uip_appdata += len1;*/
+00109     memcpy(uip_appdata, (u8_t *)uip_appdata + len1, len2);
+00110 
+00111     uip_add32(BUF->seqno, len1);
+00112     BUF->seqno[0] = uip_acc32[0];
+00113     BUF->seqno[1] = uip_acc32[1];
+00114     BUF->seqno[2] = uip_acc32[2];
+00115     BUF->seqno[3] = uip_acc32[3];
+00116     
+00117     /* Recalculate the TCP checksum. */
+00118     BUF->tcpchksum = 0;
+00119     BUF->tcpchksum = ~(uip_tcpchksum());
+00120 
+00121 #if !UIP_CONF_IPV6
+00122     /* Recalculate the IP checksum. */
+00123     BUF->ipchksum = 0;
+00124     BUF->ipchksum = ~(uip_ipchksum());
+00125 #endif /* UIP_CONF_IPV6 */
+00126 
+00127     /* Transmit the second packet. */
+00128     /*    uip_fw_output();*/
+00129     tcpip_output();
+00130   } else {
+00131     /*    uip_fw_output();*/
+00132     tcpip_output();
+00133   }
+00134      
+00135 }
+00136 /*-----------------------------------------------------------------------------*/
+