source: uKadecot/trunk/uip/net/ip/uip-split.c

Last change on this file was 158, checked in by coas-nagasima, 8 years ago

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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 uIP TCP/IP stack
30 *
31 * Author: Adam Dunkels <adam@sics.se>
32 *
33 * $Id: uip-split.c 158 2016-02-20 13:43:32Z coas-nagasima $
34 */
35
36#include <string.h>
37
38#include "net/ip/uip-split.h"
39#include "net/ip/uip.h"
40#include "net/ipv4/uip-fw.h"
41#include "net/ip/uip_arch.h"
42
43
44
45#define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
46
47/*-----------------------------------------------------------------------------*/
48void
49uip_split_output(void)
50{
51 uint16_t tcplen, len1, len2;
52
53 /* We only try to split maximum sized TCP segments. */
54 if(BUF->proto == UIP_PROTO_TCP &&
55 uip_len == UIP_BUFSIZE - UIP_LLH_LEN) {
56
57 tcplen = uip_len - UIP_TCPIP_HLEN;
58 /* Split the segment in two. If the original packet length was
59 odd, we make the second packet one byte larger. */
60 len1 = len2 = tcplen / 2;
61 if(len1 + len2 < tcplen) {
62 ++len2;
63 }
64
65 /* Create the first packet. This is done by altering the length
66 field of the IP header and updating the checksums. */
67 uip_len = len1 + UIP_TCPIP_HLEN;
68#if UIP_CONF_IPV6
69 /* For IPv6, the IP length field does not include the IPv6 IP header
70 length. */
71 BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
72 BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
73#else /* UIP_CONF_IPV6 */
74 BUF->len[0] = uip_len >> 8;
75 BUF->len[1] = uip_len & 0xff;
76#endif /* UIP_CONF_IPV6 */
77
78 /* Recalculate the TCP checksum. */
79 BUF->tcpchksum = 0;
80 BUF->tcpchksum = ~(uip_tcpchksum());
81
82#if !UIP_CONF_IPV6
83 /* Recalculate the IP checksum. */
84 BUF->ipchksum = 0;
85 BUF->ipchksum = ~(uip_ipchksum());
86#endif /* UIP_CONF_IPV6 */
87
88 /* Transmit the first packet. */
89 /* uip_fw_output();*/
90 tcpip_output();
91
92 /* Now, create the second packet. To do this, it is not enough to
93 just alter the length field, but we must also update the TCP
94 sequence number and point the uip_appdata to a new place in
95 memory. This place is detemined by the length of the first
96 packet (len1). */
97 uip_len = len2 + UIP_TCPIP_HLEN;
98#if UIP_CONF_IPV6
99 /* For IPv6, the IP length field does not include the IPv6 IP header
100 length. */
101 BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
102 BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
103#else /* UIP_CONF_IPV6 */
104 BUF->len[0] = uip_len >> 8;
105 BUF->len[1] = uip_len & 0xff;
106#endif /* UIP_CONF_IPV6 */
107
108 /* uip_appdata += len1;*/
109 memcpy(uip_appdata, (uint8_t *)uip_appdata + len1, len2);
110
111 uip_add32(BUF->seqno, len1);
112 BUF->seqno[0] = uip_acc32[0];
113 BUF->seqno[1] = uip_acc32[1];
114 BUF->seqno[2] = uip_acc32[2];
115 BUF->seqno[3] = uip_acc32[3];
116
117 /* Recalculate the TCP checksum. */
118 BUF->tcpchksum = 0;
119 BUF->tcpchksum = ~(uip_tcpchksum());
120
121#if !UIP_CONF_IPV6
122 /* Recalculate the IP checksum. */
123 BUF->ipchksum = 0;
124 BUF->ipchksum = ~(uip_ipchksum());
125#endif /* UIP_CONF_IPV6 */
126
127 /* Transmit the second packet. */
128 /* uip_fw_output();*/
129 tcpip_output();
130 } else {
131 /* uip_fw_output();*/
132 tcpip_output();
133 }
134
135}
136/*-----------------------------------------------------------------------------*/
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