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  3. <title>uIP 1.0: uip/uip_arp.c Source File</title>
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    21. 

  21. <h1>uip/uip_arp.c</h1><a href="a00138.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">/**</span>
    22. 

  22. <a name="l00002"></a>00002 <span class="comment"> * \addtogroup uip</span>
    23. 

  23. <a name="l00003"></a>00003 <span class="comment"> * @{</span>
    24. 

  24. <a name="l00004"></a>00004 <span class="comment"> */</span>
    25. 

  25. <a name="l00005"></a>00005 <span class="comment"></span>
    26. 

  26. <a name="l00006"></a>00006 <span class="comment">/**</span>
    27. 

  27. <a name="l00007"></a>00007 <span class="comment"> * \defgroup uiparp uIP Address Resolution Protocol</span>
    28. 

  28. <a name="l00008"></a>00008 <span class="comment"> * @{</span>
    29. 

  29. <a name="l00009"></a>00009 <span class="comment"> *</span>
    30. 

  30. <a name="l00010"></a>00010 <span class="comment"> * The Address Resolution Protocol ARP is used for mapping between IP</span>
    31. 

  31. <a name="l00011"></a>00011 <span class="comment"> * addresses and link level addresses such as the Ethernet MAC</span>
    32. 

  32. <a name="l00012"></a>00012 <span class="comment"> * addresses. ARP uses broadcast queries to ask for the link level</span>
    33. 

  33. <a name="l00013"></a>00013 <span class="comment"> * address of a known IP address and the host which is configured with</span>
    34. 

  34. <a name="l00014"></a>00014 <span class="comment"> * the IP address for which the query was meant, will respond with its</span>
    35. 

  35. <a name="l00015"></a>00015 <span class="comment"> * link level address.</span>
    36. 

  36. <a name="l00016"></a>00016 <span class="comment"> *</span>
    37. 

  37. <a name="l00017"></a>00017 <span class="comment"> * \note This ARP implementation only supports Ethernet.</span>
    38. 

  38. <a name="l00018"></a>00018 <span class="comment"> */</span>
    39. 

  39. <a name="l00019"></a>00019  <span class="comment"></span>
    40. 

  40. <a name="l00020"></a>00020 <span class="comment">/**</span>
    41. 

  41. <a name="l00021"></a>00021 <span class="comment"> * \file</span>
    42. 

  42. <a name="l00022"></a>00022 <span class="comment"> * Implementation of the ARP Address Resolution Protocol.</span>
    43. 

  43. <a name="l00023"></a>00023 <span class="comment"> * \author Adam Dunkels &lt;adam@dunkels.com&gt;</span>
    44. 

  44. <a name="l00024"></a>00024 <span class="comment"> *</span>
    45. 

  45. <a name="l00025"></a>00025 <span class="comment"> */</span>
    46. 

  46. <a name="l00026"></a>00026 
    47. 

  47. <a name="l00027"></a>00027 <span class="comment">/*</span>
    48. 

  48. <a name="l00028"></a>00028 <span class="comment"> * Copyright (c) 2001-2003, Adam Dunkels.</span>
    49. 

  49. <a name="l00029"></a>00029 <span class="comment"> * All rights reserved.</span>
    50. 

  50. <a name="l00030"></a>00030 <span class="comment"> *</span>
    51. 

  51. <a name="l00031"></a>00031 <span class="comment"> * Redistribution and use in source and binary forms, with or without</span>
    52. 

  52. <a name="l00032"></a>00032 <span class="comment"> * modification, are permitted provided that the following conditions</span>
    53. 

  53. <a name="l00033"></a>00033 <span class="comment"> * are met:</span>
    54. 

  54. <a name="l00034"></a>00034 <span class="comment"> * 1. Redistributions of source code must retain the above copyright</span>
    55. 

  55. <a name="l00035"></a>00035 <span class="comment"> *    notice, this list of conditions and the following disclaimer.</span>
    56. 

  56. <a name="l00036"></a>00036 <span class="comment"> * 2. Redistributions in binary form must reproduce the above copyright</span>
    57. 

  57. <a name="l00037"></a>00037 <span class="comment"> *    notice, this list of conditions and the following disclaimer in the</span>
    58. 

  58. <a name="l00038"></a>00038 <span class="comment"> *    documentation and/or other materials provided with the distribution.</span>
    59. 

  59. <a name="l00039"></a>00039 <span class="comment"> * 3. The name of the author may not be used to endorse or promote</span>
    60. 

  60. <a name="l00040"></a>00040 <span class="comment"> *    products derived from this software without specific prior</span>
    61. 

  61. <a name="l00041"></a>00041 <span class="comment"> *    written permission.</span>
    62. 

  62. <a name="l00042"></a>00042 <span class="comment"> *</span>
    63. 

  63. <a name="l00043"></a>00043 <span class="comment"> * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS</span>
    64. 

  64. <a name="l00044"></a>00044 <span class="comment"> * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED</span>
    65. 

  65. <a name="l00045"></a>00045 <span class="comment"> * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE</span>
    66. 

  66. <a name="l00046"></a>00046 <span class="comment"> * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY</span>
    67. 

  67. <a name="l00047"></a>00047 <span class="comment"> * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL</span>
    68. 

  68. <a name="l00048"></a>00048 <span class="comment"> * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE</span>
    69. 

  69. <a name="l00049"></a>00049 <span class="comment"> * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS</span>
    70. 

  70. <a name="l00050"></a>00050 <span class="comment"> * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,</span>
    71. 

  71. <a name="l00051"></a>00051 <span class="comment"> * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING</span>
    72. 

  72. <a name="l00052"></a>00052 <span class="comment"> * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS</span>
    73. 

  73. <a name="l00053"></a>00053 <span class="comment"> * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.</span>
    74. 

  74. <a name="l00054"></a>00054 <span class="comment"> *</span>
    75. 

  75. <a name="l00055"></a>00055 <span class="comment"> * This file is part of the uIP TCP/IP stack.</span>
    76. 

  76. <a name="l00056"></a>00056 <span class="comment"> *</span>
    77. 

  77. <a name="l00057"></a>00057 <span class="comment"> * $Id: uip_arp.c,v 1.8 2006/06/02 23:36:21 adam Exp $</span>
    78. 

  78. <a name="l00058"></a>00058 <span class="comment"> *</span>
    79. 

  79. <a name="l00059"></a>00059 <span class="comment"> */</span>
    80. 

  80. <a name="l00060"></a>00060 
    81. 

  81. <a name="l00061"></a>00061 
    82. 

  82. <a name="l00062"></a>00062 <span class="preprocessor">#include "<a class="code" href="a00139.html">uip_arp.h</a>"</span>
    83. 

  83. <a name="l00063"></a>00063 
    84. 

  84. <a name="l00064"></a>00064 <span class="preprocessor">#include &lt;string.h&gt;</span>
    85. 

  85. <a name="l00065"></a>00065 
    86. 

  86. <a name="l00066"></a>00066 <span class="keyword">struct </span>arp_hdr {
    87. 

  87. <a name="l00067"></a>00067   <span class="keyword">struct </span><a class="code" href="a00090.html">uip_eth_hdr</a> ethhdr;
    88. 

  88. <a name="l00068"></a>00068   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> hwtype;
    89. 

  89. <a name="l00069"></a>00069   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> protocol;
    90. 

  90. <a name="l00070"></a>00070   <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> hwlen;
    91. 

  91. <a name="l00071"></a>00071   <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> protolen;
    92. 

  92. <a name="l00072"></a>00072   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> opcode;
    93. 

  93. <a name="l00073"></a>00073   <span class="keyword">struct </span><a class="code" href="a00089.html">uip_eth_addr</a> shwaddr;
    94. 

  94. <a name="l00074"></a>00074   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> sipaddr[2];
    95. 

  95. <a name="l00075"></a>00075   <span class="keyword">struct </span><a class="code" href="a00089.html">uip_eth_addr</a> dhwaddr;
    96. 

  96. <a name="l00076"></a>00076   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> dipaddr[2];
    97. 

  97. <a name="l00077"></a>00077 };
    98. 

  98. <a name="l00078"></a>00078 
    99. 

  99. <a name="l00079"></a>00079 <span class="keyword">struct </span>ethip_hdr {
    100. 

  100. <a name="l00080"></a>00080   <span class="keyword">struct </span><a class="code" href="a00090.html">uip_eth_hdr</a> ethhdr;
    101. 

  101. <a name="l00081"></a>00081   <span class="comment">/* IP header. */</span>
    102. 

  102. <a name="l00082"></a>00082   <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> vhl,
    103. 

  103. <a name="l00083"></a>00083     tos,
    104. 

  104. <a name="l00084"></a>00084     len[2],
    105. 

  105. <a name="l00085"></a>00085     ipid[2],
    106. 

  106. <a name="l00086"></a>00086     ipoffset[2],
    107. 

  107. <a name="l00087"></a>00087     ttl,
    108. 

  108. <a name="l00088"></a>00088     proto;
    109. 

  109. <a name="l00089"></a>00089   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> ipchksum;
    110. 

  110. <a name="l00090"></a>00090   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> srcipaddr[2],
    111. 

  111. <a name="l00091"></a>00091     destipaddr[2];
    112. 

  112. <a name="l00092"></a>00092 };
    113. 

  113. <a name="l00093"></a>00093 
    114. 

  114. <a name="l00094"></a><a class="code" href="a00152.html#g7a7c46ffaba30477b8c9e3e61bd2e106">00094</a> <span class="preprocessor">#define ARP_REQUEST 1</span>
    115. 

  115. <a name="l00095"></a><a class="code" href="a00152.html#g06ba7b414e718081998f2814090debf1">00095</a> <span class="preprocessor"></span><span class="preprocessor">#define ARP_REPLY   2</span>
    116. 

  116. <a name="l00096"></a>00096 <span class="preprocessor"></span>
    117. 

  117. <a name="l00097"></a><a class="code" href="a00152.html#gbb56b549f7ab4d86e1cc39b8afc70d1e">00097</a> <span class="preprocessor">#define ARP_HWTYPE_ETH 1</span>
    118. 

  118. <a name="l00098"></a>00098 <span class="preprocessor"></span>
    119. 

  119. <a name="l00099"></a>00099 <span class="keyword">struct </span>arp_entry {
    120. 

  120. <a name="l00100"></a>00100   <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> ipaddr[2];
    121. 

  121. <a name="l00101"></a>00101   <span class="keyword">struct </span><a class="code" href="a00089.html">uip_eth_addr</a> ethaddr;
    122. 

  122. <a name="l00102"></a>00102   <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> time;
    123. 

  123. <a name="l00103"></a>00103 };
    124. 

  124. <a name="l00104"></a>00104 
    125. 

  125. <a name="l00105"></a>00105 <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">struct </span><a class="code" href="a00089.html">uip_eth_addr</a> broadcast_ethaddr =
    126. 

  126. <a name="l00106"></a>00106   {{0xff,0xff,0xff,0xff,0xff,0xff}};
    127. 

  127. <a name="l00107"></a>00107 <span class="keyword">static</span> <span class="keyword">const</span> <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> broadcast_ipaddr[2] = {0xffff,0xffff};
    128. 

  128. <a name="l00108"></a>00108 
    129. 

  129. <a name="l00109"></a>00109 <span class="keyword">static</span> <span class="keyword">struct </span>arp_entry arp_table[<a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>];
    130. 

  130. <a name="l00110"></a>00110 <span class="keyword">static</span> <a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> ipaddr[2];
    131. 

  131. <a name="l00111"></a>00111 <span class="keyword">static</span> <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> i, c;
    132. 

  132. <a name="l00112"></a>00112 
    133. 

  133. <a name="l00113"></a>00113 <span class="keyword">static</span> <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> arptime;
    134. 

  134. <a name="l00114"></a>00114 <span class="keyword">static</span> <a class="code" href="a00153.html#g4caecabca98b43919dd11be1c0d4cd8e">u8_t</a> tmpage;
    135. 

  135. <a name="l00115"></a>00115 
    136. 

  136. <a name="l00116"></a><a class="code" href="a00152.html#g24f52ac52d6e714cb04a5aa01be3bdd0">00116</a> <span class="preprocessor">#define BUF   ((struct arp_hdr *)&amp;uip_buf[0])</span>
    137. 

  137. <a name="l00117"></a><a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">00117</a> <span class="preprocessor"></span><span class="preprocessor">#define IPBUF ((struct ethip_hdr *)&amp;uip_buf[0])</span>
    138. 

  138. <a name="l00118"></a>00118 <span class="preprocessor"></span><span class="comment">/*-----------------------------------------------------------------------------------*/</span><span class="comment"></span>
    139. 

  139. <a name="l00119"></a>00119 <span class="comment">/**</span>
    140. 

  140. <a name="l00120"></a>00120 <span class="comment"> * Initialize the ARP module.</span>
    141. 

  141. <a name="l00121"></a>00121 <span class="comment"> *</span>
    142. 

  142. <a name="l00122"></a>00122 <span class="comment"> */</span>
    143. 

  143. <a name="l00123"></a>00123 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    144. 

  144. <a name="l00124"></a>00124 <span class="keywordtype">void</span>
    145. 

  145. <a name="l00125"></a><a class="code" href="a00152.html#g2d9d28afa353f662b9bb5234fc419f72">00125</a> <a class="code" href="a00152.html#g2d9d28afa353f662b9bb5234fc419f72">uip_arp_init</a>(<span class="keywordtype">void</span>)
    146. 

  146. <a name="l00126"></a>00126 {
    147. 

  147. <a name="l00127"></a>00127   <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    148. 

  148. <a name="l00128"></a>00128     memset(arp_table[i].ipaddr, 0, 4);
    149. 

  149. <a name="l00129"></a>00129   }
    150. 

  150. <a name="l00130"></a>00130 }
    151. 

  151. <a name="l00131"></a>00131 <span class="comment">/*-----------------------------------------------------------------------------------*/</span><span class="comment"></span>
    152. 

  152. <a name="l00132"></a>00132 <span class="comment">/**</span>
    153. 

  153. <a name="l00133"></a>00133 <span class="comment"> * Periodic ARP processing function.</span>
    154. 

  154. <a name="l00134"></a>00134 <span class="comment"> *</span>
    155. 

  155. <a name="l00135"></a>00135 <span class="comment"> * This function performs periodic timer processing in the ARP module</span>
    156. 

  156. <a name="l00136"></a>00136 <span class="comment"> * and should be called at regular intervals. The recommended interval</span>
    157. 

  157. <a name="l00137"></a>00137 <span class="comment"> * is 10 seconds between the calls.</span>
    158. 

  158. <a name="l00138"></a>00138 <span class="comment"> *</span>
    159. 

  159. <a name="l00139"></a>00139 <span class="comment"> */</span>
    160. 

  160. <a name="l00140"></a>00140 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    161. 

  161. <a name="l00141"></a>00141 <span class="keywordtype">void</span>
    162. 

  162. <a name="l00142"></a><a class="code" href="a00152.html#g058a8e6025f67b021862281f1911fcef">00142</a> <a class="code" href="a00152.html#g058a8e6025f67b021862281f1911fcef">uip_arp_timer</a>(<span class="keywordtype">void</span>)
    163. 

  163. <a name="l00143"></a>00143 {
    164. 

  164. <a name="l00144"></a>00144   <span class="keyword">struct </span>arp_entry *tabptr;
    165. 

  165. <a name="l00145"></a>00145   
    166. 

  166. <a name="l00146"></a>00146   ++arptime;
    167. 

  167. <a name="l00147"></a>00147   <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    168. 

  168. <a name="l00148"></a>00148     tabptr = &amp;arp_table[i];
    169. 

  169. <a name="l00149"></a>00149     <span class="keywordflow">if</span>((tabptr-&gt;ipaddr[0] | tabptr-&gt;ipaddr[1]) != 0 &amp;&amp;
    170. 

  170. <a name="l00150"></a>00150        arptime - tabptr-&gt;time &gt;= <a class="code" href="a00153.html#g3090117ef3ff5775b77cb1960e442d07">UIP_ARP_MAXAGE</a>) {
    171. 

  171. <a name="l00151"></a>00151       memset(tabptr-&gt;ipaddr, 0, 4);
    172. 

  172. <a name="l00152"></a>00152     }
    173. 

  173. <a name="l00153"></a>00153   }
    174. 

  174. <a name="l00154"></a>00154 
    175. 

  175. <a name="l00155"></a>00155 }
    176. 

  176. <a name="l00156"></a>00156 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    177. 

  177. <a name="l00157"></a>00157 <span class="keyword">static</span> <span class="keywordtype">void</span>
    178. 

  178. <a name="l00158"></a>00158 uip_arp_update(<a class="code" href="a00153.html#g77570ac4fcab86864fa1916e55676da2">u16_t</a> *ipaddr, <span class="keyword">struct</span> <a class="code" href="a00089.html">uip_eth_addr</a> *ethaddr)
    179. 

  179. <a name="l00159"></a>00159 {
    180. 

  180. <a name="l00160"></a>00160   <span class="keyword">register</span> <span class="keyword">struct </span>arp_entry *tabptr;
    181. 

  181. <a name="l00161"></a>00161   <span class="comment">/* Walk through the ARP mapping table and try to find an entry to</span>
    182. 

  182. <a name="l00162"></a>00162 <span class="comment">     update. If none is found, the IP -&gt; MAC address mapping is</span>
    183. 

  183. <a name="l00163"></a>00163 <span class="comment">     inserted in the ARP table. */</span>
    184. 

  184. <a name="l00164"></a>00164   <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    185. 

  185. <a name="l00165"></a>00165 
    186. 

  186. <a name="l00166"></a>00166     tabptr = &amp;arp_table[i];
    187. 

  187. <a name="l00167"></a>00167     <span class="comment">/* Only check those entries that are actually in use. */</span>
    188. 

  188. <a name="l00168"></a>00168     <span class="keywordflow">if</span>(tabptr-&gt;ipaddr[0] != 0 &amp;&amp;
    189. 

  189. <a name="l00169"></a>00169        tabptr-&gt;ipaddr[1] != 0) {
    190. 

  190. <a name="l00170"></a>00170 
    191. 

  191. <a name="l00171"></a>00171       <span class="comment">/* Check if the source IP address of the incoming packet matches</span>
    192. 

  192. <a name="l00172"></a>00172 <span class="comment">         the IP address in this ARP table entry. */</span>
    193. 

  193. <a name="l00173"></a>00173       <span class="keywordflow">if</span>(ipaddr[0] == tabptr-&gt;ipaddr[0] &amp;&amp;
    194. 

  194. <a name="l00174"></a>00174          ipaddr[1] == tabptr-&gt;ipaddr[1]) {
    195. 

  195. <a name="l00175"></a>00175          
    196. 

  196. <a name="l00176"></a>00176         <span class="comment">/* An old entry found, update this and return. */</span>
    197. 

  197. <a name="l00177"></a>00177         memcpy(tabptr-&gt;ethaddr.addr, ethaddr-&gt;<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    198. 

  198. <a name="l00178"></a>00178         tabptr-&gt;time = arptime;
    199. 

  199. <a name="l00179"></a>00179 
    200. 

  200. <a name="l00180"></a>00180         <span class="keywordflow">return</span>;
    201. 

  201. <a name="l00181"></a>00181       }
    202. 

  202. <a name="l00182"></a>00182     }
    203. 

  203. <a name="l00183"></a>00183   }
    204. 

  204. <a name="l00184"></a>00184 
    205. 

  205. <a name="l00185"></a>00185   <span class="comment">/* If we get here, no existing ARP table entry was found, so we</span>
    206. 

  206. <a name="l00186"></a>00186 <span class="comment">     create one. */</span>
    207. 

  207. <a name="l00187"></a>00187 
    208. 

  208. <a name="l00188"></a>00188   <span class="comment">/* First, we try to find an unused entry in the ARP table. */</span>
    209. 

  209. <a name="l00189"></a>00189   <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    210. 

  210. <a name="l00190"></a>00190     tabptr = &amp;arp_table[i];
    211. 

  211. <a name="l00191"></a>00191     <span class="keywordflow">if</span>(tabptr-&gt;ipaddr[0] == 0 &amp;&amp;
    212. 

  212. <a name="l00192"></a>00192        tabptr-&gt;ipaddr[1] == 0) {
    213. 

  213. <a name="l00193"></a>00193       <span class="keywordflow">break</span>;
    214. 

  214. <a name="l00194"></a>00194     }
    215. 

  215. <a name="l00195"></a>00195   }
    216. 

  216. <a name="l00196"></a>00196 
    217. 

  217. <a name="l00197"></a>00197   <span class="comment">/* If no unused entry is found, we try to find the oldest entry and</span>
    218. 

  218. <a name="l00198"></a>00198 <span class="comment">     throw it away. */</span>
    219. 

  219. <a name="l00199"></a>00199   <span class="keywordflow">if</span>(i == <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>) {
    220. 

  220. <a name="l00200"></a>00200     tmpage = 0;
    221. 

  221. <a name="l00201"></a>00201     c = 0;
    222. 

  222. <a name="l00202"></a>00202     <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    223. 

  223. <a name="l00203"></a>00203       tabptr = &amp;arp_table[i];
    224. 

  224. <a name="l00204"></a>00204       <span class="keywordflow">if</span>(arptime - tabptr-&gt;time &gt; tmpage) {
    225. 

  225. <a name="l00205"></a>00205         tmpage = arptime - tabptr-&gt;time;
    226. 

  226. <a name="l00206"></a>00206         c = i;
    227. 

  227. <a name="l00207"></a>00207       }
    228. 

  228. <a name="l00208"></a>00208     }
    229. 

  229. <a name="l00209"></a>00209     i = c;
    230. 

  230. <a name="l00210"></a>00210     tabptr = &amp;arp_table[i];
    231. 

  231. <a name="l00211"></a>00211   }
    232. 

  232. <a name="l00212"></a>00212 
    233. 

  233. <a name="l00213"></a>00213   <span class="comment">/* Now, i is the ARP table entry which we will fill with the new</span>
    234. 

  234. <a name="l00214"></a>00214 <span class="comment">     information. */</span>
    235. 

  235. <a name="l00215"></a>00215   memcpy(tabptr-&gt;ipaddr, ipaddr, 4);
    236. 

  236. <a name="l00216"></a>00216   memcpy(tabptr-&gt;ethaddr.addr, ethaddr-&gt;<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    237. 

  237. <a name="l00217"></a>00217   tabptr-&gt;time = arptime;
    238. 

  238. <a name="l00218"></a>00218 }
    239. 

  239. <a name="l00219"></a>00219 <span class="comment">/*-----------------------------------------------------------------------------------*/</span><span class="comment"></span>
    240. 

  240. <a name="l00220"></a>00220 <span class="comment">/**</span>
    241. 

  241. <a name="l00221"></a>00221 <span class="comment"> * ARP processing for incoming IP packets</span>
    242. 

  242. <a name="l00222"></a>00222 <span class="comment"> *</span>
    243. 

  243. <a name="l00223"></a>00223 <span class="comment"> * This function should be called by the device driver when an IP</span>
    244. 

  244. <a name="l00224"></a>00224 <span class="comment"> * packet has been received. The function will check if the address is</span>
    245. 

  245. <a name="l00225"></a>00225 <span class="comment"> * in the ARP cache, and if so the ARP cache entry will be</span>
    246. 

  246. <a name="l00226"></a>00226 <span class="comment"> * refreshed. If no ARP cache entry was found, a new one is created.</span>
    247. 

  247. <a name="l00227"></a>00227 <span class="comment"> *</span>
    248. 

  248. <a name="l00228"></a>00228 <span class="comment"> * This function expects an IP packet with a prepended Ethernet header</span>
    249. 

  249. <a name="l00229"></a>00229 <span class="comment"> * in the uip_buf[] buffer, and the length of the packet in the global</span>
    250. 

  250. <a name="l00230"></a>00230 <span class="comment"> * variable uip_len.</span>
    251. 

  251. <a name="l00231"></a>00231 <span class="comment"> */</span>
    252. 

  252. <a name="l00232"></a>00232 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    253. 

  253. <a name="l00233"></a>00233 <span class="preprocessor">#if 0</span>
    254. 

  254. <a name="l00234"></a>00234 <span class="preprocessor"></span><span class="keywordtype">void</span>
    255. 

  255. <a name="l00235"></a>00235 <a class="code" href="a00152.html#g737337d6a51e31b236c8233d024138a8">uip_arp_ipin</a>(<span class="keywordtype">void</span>)
    256. 

  256. <a name="l00236"></a>00236 {
    257. 

  257. <a name="l00237"></a>00237   <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> -= <span class="keyword">sizeof</span>(<span class="keyword">struct </span><a class="code" href="a00090.html">uip_eth_hdr</a>);
    258. 

  258. <a name="l00238"></a>00238         
    259. 

  259. <a name="l00239"></a>00239   <span class="comment">/* Only insert/update an entry if the source IP address of the</span>
    260. 

  260. <a name="l00240"></a>00240 <span class="comment">     incoming IP packet comes from a host on the local network. */</span>
    261. 

  261. <a name="l00241"></a>00241   <span class="keywordflow">if</span>((<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;srcipaddr[0] &amp; <a class="code" href="a00150.html#g3237be0d9ec457de0177689ee23c0d5c">uip_netmask</a>[0]) !=
    262. 

  262. <a name="l00242"></a>00242      (<a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>[0] &amp; <a class="code" href="a00150.html#g3237be0d9ec457de0177689ee23c0d5c">uip_netmask</a>[0])) {
    263. 

  263. <a name="l00243"></a>00243     <span class="keywordflow">return</span>;
    264. 

  264. <a name="l00244"></a>00244   }
    265. 

  265. <a name="l00245"></a>00245   <span class="keywordflow">if</span>((<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;srcipaddr[1] &amp; uip_netmask[1]) !=
    266. 

  266. <a name="l00246"></a>00246      (<a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>[1] &amp; uip_netmask[1])) {
    267. 

  267. <a name="l00247"></a>00247     <span class="keywordflow">return</span>;
    268. 

  268. <a name="l00248"></a>00248   }
    269. 

  269. <a name="l00249"></a>00249   uip_arp_update(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;srcipaddr, &amp;(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;ethhdr.src));
    270. 

  270. <a name="l00250"></a>00250   
    271. 

  271. <a name="l00251"></a>00251   <span class="keywordflow">return</span>;
    272. 

  272. <a name="l00252"></a>00252 }
    273. 

  273. <a name="l00253"></a>00253 <span class="preprocessor">#endif </span><span class="comment">/* 0 */</span>
    274. 

  274. <a name="l00254"></a>00254 <span class="comment">/*-----------------------------------------------------------------------------------*/</span><span class="comment"></span>
    275. 

  275. <a name="l00255"></a>00255 <span class="comment">/**</span>
    276. 

  276. <a name="l00256"></a>00256 <span class="comment"> * ARP processing for incoming ARP packets.</span>
    277. 

  277. <a name="l00257"></a>00257 <span class="comment"> *</span>
    278. 

  278. <a name="l00258"></a>00258 <span class="comment"> * This function should be called by the device driver when an ARP</span>
    279. 

  279. <a name="l00259"></a>00259 <span class="comment"> * packet has been received. The function will act differently</span>
    280. 

  280. <a name="l00260"></a>00260 <span class="comment"> * depending on the ARP packet type: if it is a reply for a request</span>
    281. 

  281. <a name="l00261"></a>00261 <span class="comment"> * that we previously sent out, the ARP cache will be filled in with</span>
    282. 

  282. <a name="l00262"></a>00262 <span class="comment"> * the values from the ARP reply. If the incoming ARP packet is an ARP</span>
    283. 

  283. <a name="l00263"></a>00263 <span class="comment"> * request for our IP address, an ARP reply packet is created and put</span>
    284. 

  284. <a name="l00264"></a>00264 <span class="comment"> * into the uip_buf[] buffer.</span>
    285. 

  285. <a name="l00265"></a>00265 <span class="comment"> *</span>
    286. 

  286. <a name="l00266"></a>00266 <span class="comment"> * When the function returns, the value of the global variable uip_len</span>
    287. 

  287. <a name="l00267"></a>00267 <span class="comment"> * indicates whether the device driver should send out a packet or</span>
    288. 

  288. <a name="l00268"></a>00268 <span class="comment"> * not. If uip_len is zero, no packet should be sent. If uip_len is</span>
    289. 

  289. <a name="l00269"></a>00269 <span class="comment"> * non-zero, it contains the length of the outbound packet that is</span>
    290. 

  290. <a name="l00270"></a>00270 <span class="comment"> * present in the uip_buf[] buffer.</span>
    291. 

  291. <a name="l00271"></a>00271 <span class="comment"> *</span>
    292. 

  292. <a name="l00272"></a>00272 <span class="comment"> * This function expects an ARP packet with a prepended Ethernet</span>
    293. 

  293. <a name="l00273"></a>00273 <span class="comment"> * header in the uip_buf[] buffer, and the length of the packet in the</span>
    294. 

  294. <a name="l00274"></a>00274 <span class="comment"> * global variable uip_len.</span>
    295. 

  295. <a name="l00275"></a>00275 <span class="comment"> */</span>
    296. 

  296. <a name="l00276"></a>00276 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    297. 

  297. <a name="l00277"></a>00277 <span class="keywordtype">void</span>
    298. 

  298. <a name="l00278"></a><a class="code" href="a00152.html#g902c4a360134096224bc2655f623aa5f">00278</a> <a class="code" href="a00152.html#g902c4a360134096224bc2655f623aa5f">uip_arp_arpin</a>(<span class="keywordtype">void</span>)
    299. 

  299. <a name="l00279"></a>00279 {
    300. 

  300. <a name="l00280"></a>00280   
    301. 

  301. <a name="l00281"></a>00281   <span class="keywordflow">if</span>(<a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> &lt; <span class="keyword">sizeof</span>(<span class="keyword">struct</span> arp_hdr)) {
    302. 

  302. <a name="l00282"></a>00282     <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> = 0;
    303. 

  303. <a name="l00283"></a>00283     <span class="keywordflow">return</span>;
    304. 

  304. <a name="l00284"></a>00284   }
    305. 

  305. <a name="l00285"></a>00285   <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> = 0;
    306. 

  306. <a name="l00286"></a>00286   
    307. 

  307. <a name="l00287"></a>00287   <span class="keywordflow">switch</span>(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;opcode) {
    308. 

  308. <a name="l00288"></a>00288   <span class="keywordflow">case</span> <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g7a7c46ffaba30477b8c9e3e61bd2e106">ARP_REQUEST</a>):
    309. 

  309. <a name="l00289"></a>00289     <span class="comment">/* ARP request. If it asked for our address, we send out a</span>
    310. 

  310. <a name="l00290"></a>00290 <span class="comment">       reply. */</span>
    311. 

  311. <a name="l00291"></a>00291     <span class="keywordflow">if</span>(<a class="code" href="a00148.html#g210e629f7252e4bc8458cbdf260b3318">uip_ipaddr_cmp</a>(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dipaddr, <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>)) {
    312. 

  312. <a name="l00292"></a>00292       <span class="comment">/* First, we register the one who made the request in our ARP</span>
    313. 

  313. <a name="l00293"></a>00293 <span class="comment">         table, since it is likely that we will do more communication</span>
    314. 

  314. <a name="l00294"></a>00294 <span class="comment">         with this host in the future. */</span>
    315. 

  315. <a name="l00295"></a>00295       uip_arp_update(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr, &amp;<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;shwaddr);
    316. 

  316. <a name="l00296"></a>00296       
    317. 

  317. <a name="l00297"></a>00297       <span class="comment">/* The reply opcode is 2. */</span>
    318. 

  318. <a name="l00298"></a>00298       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;opcode = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(2);
    319. 

  319. <a name="l00299"></a>00299 
    320. 

  320. <a name="l00300"></a>00300       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dhwaddr.addr, <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;shwaddr.addr, 6);
    321. 

  321. <a name="l00301"></a>00301       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;shwaddr.addr, <a class="code" href="a00150.html#g499bb98a0b4ae9a98553ede81317606d">uip_ethaddr</a>.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    322. 

  322. <a name="l00302"></a>00302       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.src.addr, <a class="code" href="a00150.html#g499bb98a0b4ae9a98553ede81317606d">uip_ethaddr</a>.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    323. 

  323. <a name="l00303"></a>00303       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.dest.addr, <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dhwaddr.addr, 6);
    324. 

  324. <a name="l00304"></a>00304       
    325. 

  325. <a name="l00305"></a>00305       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dipaddr[0] = <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr[0];
    326. 

  326. <a name="l00306"></a>00306       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dipaddr[1] = <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr[1];
    327. 

  327. <a name="l00307"></a>00307       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr[0] = <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>[0];
    328. 

  328. <a name="l00308"></a>00308       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr[1] = <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>[1];
    329. 

  329. <a name="l00309"></a>00309 
    330. 

  330. <a name="l00310"></a>00310       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.type = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g3e1562e8a6de32268e5df92a52152f91">UIP_ETHTYPE_ARP</a>);
    331. 

  331. <a name="l00311"></a>00311       <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> = <span class="keyword">sizeof</span>(<span class="keyword">struct </span>arp_hdr);
    332. 

  332. <a name="l00312"></a>00312     }
    333. 

  333. <a name="l00313"></a>00313     <span class="keywordflow">break</span>;
    334. 

  334. <a name="l00314"></a>00314   <span class="keywordflow">case</span> <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g06ba7b414e718081998f2814090debf1">ARP_REPLY</a>):
    335. 

  335. <a name="l00315"></a>00315     <span class="comment">/* ARP reply. We insert or update the ARP table if it was meant</span>
    336. 

  336. <a name="l00316"></a>00316 <span class="comment">       for us. */</span>
    337. 

  337. <a name="l00317"></a>00317     <span class="keywordflow">if</span>(<a class="code" href="a00148.html#g210e629f7252e4bc8458cbdf260b3318">uip_ipaddr_cmp</a>(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dipaddr, <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>)) {
    338. 

  338. <a name="l00318"></a>00318       uip_arp_update(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr, &amp;<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;shwaddr);
    339. 

  339. <a name="l00319"></a>00319     }
    340. 

  340. <a name="l00320"></a>00320     <span class="keywordflow">break</span>;
    341. 

  341. <a name="l00321"></a>00321   }
    342. 

  342. <a name="l00322"></a>00322 
    343. 

  343. <a name="l00323"></a>00323   <span class="keywordflow">return</span>;
    344. 

  344. <a name="l00324"></a>00324 }
    345. 

  345. <a name="l00325"></a>00325 <span class="comment">/*-----------------------------------------------------------------------------------*/</span><span class="comment"></span>
    346. 

  346. <a name="l00326"></a>00326 <span class="comment">/**</span>
    347. 

  347. <a name="l00327"></a>00327 <span class="comment"> * Prepend Ethernet header to an outbound IP packet and see if we need</span>
    348. 

  348. <a name="l00328"></a>00328 <span class="comment"> * to send out an ARP request.</span>
    349. 

  349. <a name="l00329"></a>00329 <span class="comment"> *</span>
    350. 

  350. <a name="l00330"></a>00330 <span class="comment"> * This function should be called before sending out an IP packet. The</span>
    351. 

  351. <a name="l00331"></a>00331 <span class="comment"> * function checks the destination IP address of the IP packet to see</span>
    352. 

  352. <a name="l00332"></a>00332 <span class="comment"> * what Ethernet MAC address that should be used as a destination MAC</span>
    353. 

  353. <a name="l00333"></a>00333 <span class="comment"> * address on the Ethernet.</span>
    354. 

  354. <a name="l00334"></a>00334 <span class="comment"> *</span>
    355. 

  355. <a name="l00335"></a>00335 <span class="comment"> * If the destination IP address is in the local network (determined</span>
    356. 

  356. <a name="l00336"></a>00336 <span class="comment"> * by logical ANDing of netmask and our IP address), the function</span>
    357. 

  357. <a name="l00337"></a>00337 <span class="comment"> * checks the ARP cache to see if an entry for the destination IP</span>
    358. 

  358. <a name="l00338"></a>00338 <span class="comment"> * address is found. If so, an Ethernet header is prepended and the</span>
    359. 

  359. <a name="l00339"></a>00339 <span class="comment"> * function returns. If no ARP cache entry is found for the</span>
    360. 

  360. <a name="l00340"></a>00340 <span class="comment"> * destination IP address, the packet in the uip_buf[] is replaced by</span>
    361. 

  361. <a name="l00341"></a>00341 <span class="comment"> * an ARP request packet for the IP address. The IP packet is dropped</span>
    362. 

  362. <a name="l00342"></a>00342 <span class="comment"> * and it is assumed that they higher level protocols (e.g., TCP)</span>
    363. 

  363. <a name="l00343"></a>00343 <span class="comment"> * eventually will retransmit the dropped packet.</span>
    364. 

  364. <a name="l00344"></a>00344 <span class="comment"> *</span>
    365. 

  365. <a name="l00345"></a>00345 <span class="comment"> * If the destination IP address is not on the local network, the IP</span>
    366. 

  366. <a name="l00346"></a>00346 <span class="comment"> * address of the default router is used instead.</span>
    367. 

  367. <a name="l00347"></a>00347 <span class="comment"> *</span>
    368. 

  368. <a name="l00348"></a>00348 <span class="comment"> * When the function returns, a packet is present in the uip_buf[]</span>
    369. 

  369. <a name="l00349"></a>00349 <span class="comment"> * buffer, and the length of the packet is in the global variable</span>
    370. 

  370. <a name="l00350"></a>00350 <span class="comment"> * uip_len.</span>
    371. 

  371. <a name="l00351"></a>00351 <span class="comment"> */</span>
    372. 

  372. <a name="l00352"></a>00352 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    373. 

  373. <a name="l00353"></a>00353 <span class="keywordtype">void</span>
    374. 

  374. <a name="l00354"></a><a class="code" href="a00152.html#g54b27e45df15e10a0eb1a3e3a91417d2">00354</a> <a class="code" href="a00152.html#g54b27e45df15e10a0eb1a3e3a91417d2">uip_arp_out</a>(<span class="keywordtype">void</span>)
    375. 

  375. <a name="l00355"></a>00355 {
    376. 

  376. <a name="l00356"></a>00356   <span class="keyword">struct </span>arp_entry *tabptr;
    377. 

  377. <a name="l00357"></a>00357   
    378. 

  378. <a name="l00358"></a>00358   <span class="comment">/* Find the destination IP address in the ARP table and construct</span>
    379. 

  379. <a name="l00359"></a>00359 <span class="comment">     the Ethernet header. If the destination IP addres isn't on the</span>
    380. 

  380. <a name="l00360"></a>00360 <span class="comment">     local network, we use the default router's IP address instead.</span>
    381. 

  381. <a name="l00361"></a>00361 <span class="comment"></span>
    382. 

  382. <a name="l00362"></a>00362 <span class="comment">     If not ARP table entry is found, we overwrite the original IP</span>
    383. 

  383. <a name="l00363"></a>00363 <span class="comment">     packet with an ARP request for the IP address. */</span>
    384. 

  384. <a name="l00364"></a>00364 
    385. 

  385. <a name="l00365"></a>00365   <span class="comment">/* First check if destination is a local broadcast. */</span>
    386. 

  386. <a name="l00366"></a>00366   <span class="keywordflow">if</span>(<a class="code" href="a00148.html#g210e629f7252e4bc8458cbdf260b3318">uip_ipaddr_cmp</a>(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;destipaddr, broadcast_ipaddr)) {
    387. 

  387. <a name="l00367"></a>00367     memcpy(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;ethhdr.dest.addr, broadcast_ethaddr.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    388. 

  388. <a name="l00368"></a>00368   } <span class="keywordflow">else</span> {
    389. 

  389. <a name="l00369"></a>00369     <span class="comment">/* Check if the destination address is on the local network. */</span>
    390. 

  390. <a name="l00370"></a>00370     <span class="keywordflow">if</span>(!<a class="code" href="a00148.html#g6b16e0bac41821c1fbe0c267071642f0">uip_ipaddr_maskcmp</a>(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;destipaddr, <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>, uip_netmask)) {
    391. 

  391. <a name="l00371"></a>00371       <span class="comment">/* Destination address was not on the local network, so we need to</span>
    392. 

  392. <a name="l00372"></a>00372 <span class="comment">         use the default router's IP address instead of the destination</span>
    393. 

  393. <a name="l00373"></a>00373 <span class="comment">         address when determining the MAC address. */</span>
    394. 

  394. <a name="l00374"></a>00374       <a class="code" href="a00148.html#g769512993b7b27271909d6daa4748b60">uip_ipaddr_copy</a>(ipaddr, <a class="code" href="a00150.html#g20df5c82f2a15a508c19e505b5d9de2b">uip_draddr</a>);
    395. 

  395. <a name="l00375"></a>00375     } <span class="keywordflow">else</span> {
    396. 

  396. <a name="l00376"></a>00376       <span class="comment">/* Else, we use the destination IP address. */</span>
    397. 

  397. <a name="l00377"></a>00377       <a class="code" href="a00148.html#g769512993b7b27271909d6daa4748b60">uip_ipaddr_copy</a>(ipaddr, <a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;destipaddr);
    398. 

  398. <a name="l00378"></a>00378     }
    399. 

  399. <a name="l00379"></a>00379       
    400. 

  400. <a name="l00380"></a>00380     <span class="keywordflow">for</span>(i = 0; i &lt; <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>; ++i) {
    401. 

  401. <a name="l00381"></a>00381       tabptr = &amp;arp_table[i];
    402. 

  402. <a name="l00382"></a>00382       <span class="keywordflow">if</span>(<a class="code" href="a00148.html#g210e629f7252e4bc8458cbdf260b3318">uip_ipaddr_cmp</a>(ipaddr, tabptr-&gt;ipaddr)) {
    403. 

  403. <a name="l00383"></a>00383         <span class="keywordflow">break</span>;
    404. 

  404. <a name="l00384"></a>00384       }
    405. 

  405. <a name="l00385"></a>00385     }
    406. 

  406. <a name="l00386"></a>00386 
    407. 

  407. <a name="l00387"></a>00387     <span class="keywordflow">if</span>(i == <a class="code" href="a00153.html#gb1455b27c06532a399cf06d2c1d6d08d">UIP_ARPTAB_SIZE</a>) {
    408. 

  408. <a name="l00388"></a>00388       <span class="comment">/* The destination address was not in our ARP table, so we</span>
    409. 

  409. <a name="l00389"></a>00389 <span class="comment">         overwrite the IP packet with an ARP request. */</span>
    410. 

  410. <a name="l00390"></a>00390 
    411. 

  411. <a name="l00391"></a>00391       memset(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.dest.addr, 0xff, 6);
    412. 

  412. <a name="l00392"></a>00392       memset(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dhwaddr.addr, 0x00, 6);
    413. 

  413. <a name="l00393"></a>00393       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.src.addr, <a class="code" href="a00150.html#g499bb98a0b4ae9a98553ede81317606d">uip_ethaddr</a>.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    414. 

  414. <a name="l00394"></a>00394       memcpy(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;shwaddr.addr, <a class="code" href="a00150.html#g499bb98a0b4ae9a98553ede81317606d">uip_ethaddr</a>.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    415. 

  415. <a name="l00395"></a>00395     
    416. 

  416. <a name="l00396"></a>00396       <a class="code" href="a00148.html#g769512993b7b27271909d6daa4748b60">uip_ipaddr_copy</a>(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;dipaddr, ipaddr);
    417. 

  417. <a name="l00397"></a>00397       <a class="code" href="a00148.html#g769512993b7b27271909d6daa4748b60">uip_ipaddr_copy</a>(<a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;sipaddr, <a class="code" href="a00150.html#g7d3673f52f5846b6961d23b150decd54">uip_hostaddr</a>);
    418. 

  418. <a name="l00398"></a>00398       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;opcode = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g7a7c46ffaba30477b8c9e3e61bd2e106">ARP_REQUEST</a>); <span class="comment">/* ARP request. */</span>
    419. 

  419. <a name="l00399"></a>00399       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;hwtype = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#gbb56b549f7ab4d86e1cc39b8afc70d1e">ARP_HWTYPE_ETH</a>);
    420. 

  420. <a name="l00400"></a>00400       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;protocol = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g03d140db75de3d3cdfbbab1c4fed8d8d">UIP_ETHTYPE_IP</a>);
    421. 

  421. <a name="l00401"></a>00401       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;hwlen = 6;
    422. 

  422. <a name="l00402"></a>00402       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;protolen = 4;
    423. 

  423. <a name="l00403"></a>00403       <a class="code" href="a00150.html#g24f52ac52d6e714cb04a5aa01be3bdd0">BUF</a>-&gt;ethhdr.type = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g3e1562e8a6de32268e5df92a52152f91">UIP_ETHTYPE_ARP</a>);
    424. 

  424. <a name="l00404"></a>00404 
    425. 

  425. <a name="l00405"></a>00405       <a class="code" href="a00150.html#g561b8eda32e059d4e7397f776268cc63">uip_appdata</a> = &amp;<a class="code" href="a00146.html#gb81e78f890dbbee50c533a9734b74fd9">uip_buf</a>[<a class="code" href="a00150.html#gee37386b2ab828787c05227eb109def7">UIP_TCPIP_HLEN</a> + <a class="code" href="a00153.html#ge6f4a2453dbd8bc60e6a82774552366a">UIP_LLH_LEN</a>];
    426. 

  426. <a name="l00406"></a>00406     
    427. 

  427. <a name="l00407"></a>00407       <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> = <span class="keyword">sizeof</span>(<span class="keyword">struct </span>arp_hdr);
    428. 

  428. <a name="l00408"></a>00408       <span class="keywordflow">return</span>;
    429. 

  429. <a name="l00409"></a>00409     }
    430. 

  430. <a name="l00410"></a>00410 
    431. 

  431. <a name="l00411"></a>00411     <span class="comment">/* Build an ethernet header. */</span>
    432. 

  432. <a name="l00412"></a>00412     memcpy(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;ethhdr.dest.addr, tabptr-&gt;ethaddr.addr, 6);
    433. 

  433. <a name="l00413"></a>00413   }
    434. 

  434. <a name="l00414"></a>00414   memcpy(<a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;ethhdr.src.addr, <a class="code" href="a00150.html#g499bb98a0b4ae9a98553ede81317606d">uip_ethaddr</a>.<a class="code" href="a00089.html#aacd5fa1806e0f0dd0bc96dd36507ad8">addr</a>, 6);
    435. 

  435. <a name="l00415"></a>00415   
    436. 

  436. <a name="l00416"></a>00416   <a class="code" href="a00152.html#g9f2196e2705036869611962425e404bf">IPBUF</a>-&gt;ethhdr.type = <a class="code" href="a00148.html#g69a7a4951ff21b302267532c21ee78fc">HTONS</a>(<a class="code" href="a00152.html#g03d140db75de3d3cdfbbab1c4fed8d8d">UIP_ETHTYPE_IP</a>);
    437. 

  437. <a name="l00417"></a>00417 
    438. 

  438. <a name="l00418"></a>00418   <a class="code" href="a00149.html#g12a33f0c09711167bdf3dd7d7cf8c5a1">uip_len</a> += <span class="keyword">sizeof</span>(<span class="keyword">struct </span><a class="code" href="a00090.html">uip_eth_hdr</a>);
    439. 

  439. <a name="l00419"></a>00419 }
    440. 

  440. <a name="l00420"></a>00420 <span class="comment">/*-----------------------------------------------------------------------------------*/</span>
    441. 

  441. <a name="l00421"></a>00421 <span class="comment"></span>
    442. 

  442. <a name="l00422"></a>00422 <span class="comment">/** @} */</span><span class="comment"></span>
    443. 

  443. <a name="l00423"></a>00423 <span class="comment">/** @} */</span>
    444. 

  444. </pre></div><hr size="1"><address style="align: right;"><small>Generated on Mon Jun 12 10:23:01 2006 for uIP 1.0 by&nbsp;
    445. 

  445. <a href="http://www.doxygen.org/index.html">
    446. 

  446. <img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.6 </small></address>
    447. 

  447. </body>
    448. 

  448. </html>
    449.