1 | /*
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2 | * Copyright (c) 2004, Swedish Institute of Computer Science.
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3 | * All rights reserved.
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4 | *
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5 | * Redistribution and use in source and binary forms, with or without
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6 | * modification, are permitted provided that the following conditions
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7 | * are met:
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8 | * 1. Redistributions of source code must retain the above copyright
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9 | * notice, this list of conditions and the following disclaimer.
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10 | * 2. Redistributions in binary form must reproduce the above copyright
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11 | * notice, this list of conditions and the following disclaimer in the
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12 | * documentation and/or other materials provided with the distribution.
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13 | * 3. Neither the name of the Institute nor the names of its contributors
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14 | * may be used to endorse or promote products derived from this software
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15 | * without specific prior written permission.
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16 | *
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17 | * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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18 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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19 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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20 | * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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21 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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22 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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23 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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24 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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25 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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26 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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27 | * SUCH DAMAGE.
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28 | *
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29 | * This file is part of the uIP TCP/IP stack
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30 | *
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31 | * Author: Adam Dunkels <adam@sics.se>
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32 | *
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33 | * $Id: uip-split.c 158 2016-02-20 13:43:32Z coas-nagasima $
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34 | */
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35 |
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36 | #include <string.h>
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37 |
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38 | #include "net/ip/uip-split.h"
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39 | #include "net/ip/uip.h"
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40 | #include "net/ipv4/uip-fw.h"
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41 | #include "net/ip/uip_arch.h"
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42 |
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43 |
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44 |
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45 | #define BUF ((struct uip_tcpip_hdr *)&uip_buf[UIP_LLH_LEN])
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46 |
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47 | /*-----------------------------------------------------------------------------*/
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48 | void
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49 | uip_split_output(void)
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50 | {
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51 | uint16_t tcplen, len1, len2;
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52 |
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53 | /* We only try to split maximum sized TCP segments. */
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54 | if(BUF->proto == UIP_PROTO_TCP &&
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55 | uip_len == UIP_BUFSIZE - UIP_LLH_LEN) {
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56 |
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57 | tcplen = uip_len - UIP_TCPIP_HLEN;
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58 | /* Split the segment in two. If the original packet length was
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59 | odd, we make the second packet one byte larger. */
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60 | len1 = len2 = tcplen / 2;
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61 | if(len1 + len2 < tcplen) {
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62 | ++len2;
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63 | }
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64 |
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65 | /* Create the first packet. This is done by altering the length
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66 | field of the IP header and updating the checksums. */
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67 | uip_len = len1 + UIP_TCPIP_HLEN;
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68 | #if UIP_CONF_IPV6
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69 | /* For IPv6, the IP length field does not include the IPv6 IP header
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70 | length. */
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71 | BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
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72 | BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
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73 | #else /* UIP_CONF_IPV6 */
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74 | BUF->len[0] = uip_len >> 8;
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75 | BUF->len[1] = uip_len & 0xff;
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76 | #endif /* UIP_CONF_IPV6 */
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77 |
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78 | /* Recalculate the TCP checksum. */
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79 | BUF->tcpchksum = 0;
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80 | BUF->tcpchksum = ~(uip_tcpchksum());
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81 |
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82 | #if !UIP_CONF_IPV6
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83 | /* Recalculate the IP checksum. */
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84 | BUF->ipchksum = 0;
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85 | BUF->ipchksum = ~(uip_ipchksum());
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86 | #endif /* UIP_CONF_IPV6 */
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87 |
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88 | /* Transmit the first packet. */
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89 | /* uip_fw_output();*/
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90 | tcpip_output();
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91 |
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92 | /* Now, create the second packet. To do this, it is not enough to
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93 | just alter the length field, but we must also update the TCP
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94 | sequence number and point the uip_appdata to a new place in
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95 | memory. This place is detemined by the length of the first
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96 | packet (len1). */
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97 | uip_len = len2 + UIP_TCPIP_HLEN;
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98 | #if UIP_CONF_IPV6
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99 | /* For IPv6, the IP length field does not include the IPv6 IP header
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100 | length. */
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101 | BUF->len[0] = ((uip_len - UIP_IPH_LEN) >> 8);
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102 | BUF->len[1] = ((uip_len - UIP_IPH_LEN) & 0xff);
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103 | #else /* UIP_CONF_IPV6 */
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104 | BUF->len[0] = uip_len >> 8;
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105 | BUF->len[1] = uip_len & 0xff;
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106 | #endif /* UIP_CONF_IPV6 */
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107 |
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108 | /* uip_appdata += len1;*/
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109 | memcpy(uip_appdata, (uint8_t *)uip_appdata + len1, len2);
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110 |
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111 | uip_add32(BUF->seqno, len1);
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112 | BUF->seqno[0] = uip_acc32[0];
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113 | BUF->seqno[1] = uip_acc32[1];
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114 | BUF->seqno[2] = uip_acc32[2];
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115 | BUF->seqno[3] = uip_acc32[3];
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116 |
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117 | /* Recalculate the TCP checksum. */
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118 | BUF->tcpchksum = 0;
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119 | BUF->tcpchksum = ~(uip_tcpchksum());
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120 |
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121 | #if !UIP_CONF_IPV6
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122 | /* Recalculate the IP checksum. */
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123 | BUF->ipchksum = 0;
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124 | BUF->ipchksum = ~(uip_ipchksum());
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125 | #endif /* UIP_CONF_IPV6 */
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126 |
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127 | /* Transmit the second packet. */
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128 | /* uip_fw_output();*/
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129 | tcpip_output();
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130 | } else {
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131 | /* uip_fw_output();*/
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132 | tcpip_output();
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133 | }
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134 |
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135 | }
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136 | /*-----------------------------------------------------------------------------*/
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