{"id":556,"date":"2010-06-10T10:21:07","date_gmt":"2010-06-10T02:21:07","guid":{"rendered":"http:\/\/www.kumouse.com\/?p=556"},"modified":"2010-06-10T10:21:07","modified_gmt":"2010-06-10T02:21:07","slug":"arp-%e5%8d%8f%e8%ae%ae-%e4%bb%a3%e7%a0%81-%e8%a7%a3%e9%87%8a","status":"publish","type":"post","link":"https:\/\/www.kumouse.com\/?p=556","title":{"rendered":"ARP \u534f\u8bae \u4ee3\u7801 \u89e3\u91ca"},"content":{"rendered":"<p>1. ARP\u9ad8\u901f\u7f13\u5b58\u7684\u6570\u636e\u7ed3\u6784<\/p>\n<blockquote>\n<p>\/* arp.h &#8211; SHA, SPA, THA, TPA *\/<\/p>\n<p>\t\t\/* \u4e92\u8054\u7f51\u5730\u5740\u89e3\u6790\u534f\u8bae&nbsp; (see RFCs 826, 920)&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t#define&nbsp;&nbsp; &nbsp;AR_HARDWARE&nbsp;&nbsp; &nbsp;1&nbsp;&nbsp; &nbsp;\/* \u4ee5\u592a\u7f51\u786c\u4ef6\u7c7b\u578b\u4ee3\u7801&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t\/* Definitions of codes used in operation field of ARP packet *\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;AR_REQUEST&nbsp;&nbsp; &nbsp;1&nbsp;&nbsp; &nbsp;\/* ARP\u8bf7\u6c42\u89e3\u51b3\u5730\u5740 ARP request to resolve address&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;AR_REPLY&nbsp;&nbsp; &nbsp;2&nbsp;&nbsp; &nbsp;\/* \u56de\u7b54\u89e3\u51b3\u7684\u8bf7\u6c42 reply to a resolve request&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t#define&nbsp;&nbsp; &nbsp;RA_REQUEST&nbsp;&nbsp; &nbsp;3&nbsp;&nbsp; &nbsp;\/* \u53cd\u5411ARP\u8bf7\u6c42 reverse ARP request (RARP packets)*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;RA_REPLY&nbsp;&nbsp; &nbsp;4&nbsp;&nbsp; &nbsp;\/* \u7b54\u590d\u53cd\u5411\u8bf7\u6c42 reply to a reverse request (RARP &quot;)*\/<\/p>\n<p>\t\tstruct&nbsp;&nbsp; &nbsp;arp&nbsp;&nbsp; &nbsp;{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_short&nbsp;&nbsp; &nbsp;ar_hwtype;&nbsp;&nbsp; &nbsp;\/* \u786c\u4ef6\u7c7b\u578b&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_short&nbsp;&nbsp; &nbsp;ar_prtype;&nbsp;&nbsp; &nbsp;\/* \u534f\u8bae\u7c7b\u578b&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_char&nbsp;&nbsp; &nbsp;ar_hwlen;&nbsp;&nbsp; &nbsp;\/* \u786c\u4ef6\u5730\u5740\u7684\u957f\u5ea6&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_char&nbsp;&nbsp; &nbsp;ar_prlen;&nbsp;&nbsp; &nbsp;\/* \u534f\u8bae\u5730\u5740\u7684\u957f\u5ea6&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_short&nbsp;&nbsp; &nbsp;ar_op;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/* ARP\u534f\u8bae\u8fd0\u4f5c\uff08\u89c1\u4e0a\u8ff0\u5217\u8868\uff09&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_char&nbsp;&nbsp; &nbsp;ar_addrs[1];&nbsp;&nbsp; &nbsp;\/* \u53d1\u9001\u8005\u548c\u76ee\u6807\u786c\u4ef6\u53ca\u539f\u5730\u5740&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t\/*&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ar_sha[???];&nbsp;&nbsp; &nbsp; &#8211; \u53d1\u4ef6\u4eba\u7684\u7269\u7406\u786c\u4ef6\u5730\u5740&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t\/*&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ar_spa[???];&nbsp;&nbsp; &nbsp; &#8211; \u53d1\u9001\u8005\u7684\u534f\u8bae\u5730\u5740\uff08IP\u5730\u5740\uff09&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t\/*&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ar_tha[???];&nbsp;&nbsp; &nbsp; &#8211; \u76ee\u6807\u7269\u7406\u786c\u4ef6\u5730\u5740&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t\/*&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ar_tpa[???];&nbsp;&nbsp; &nbsp; &#8211; \u76ee\u6807\u7684\u534f\u8bae\u5730\u5740(IP)&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t};<\/p>\n<p>\t\t#define&nbsp;&nbsp; &nbsp;SHA(p)&nbsp;&nbsp; &nbsp;(&amp;p-&gt;ar_addrs[0])&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u8ba1\u7b97\u6e90\u7269\u7406\u5730\u5740*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;SPA(p)&nbsp;&nbsp; &nbsp;(&amp;p-&gt;ar_addrs[p-&gt;ar_hwlen])&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u8ba1\u7b97\u6e90\u534f\u8bae\u5730\u5740*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;THA(p)&nbsp;&nbsp; &nbsp;(&amp;p-&gt;ar_addrs[p-&gt;ar_hwlen + p-&gt;ar_prlen])&nbsp;&nbsp; &nbsp;\/*\u8ba1\u7b97\u76ee\u6807\u7269\u7406\u5730\u5740*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;TPA(p)&nbsp;&nbsp; &nbsp;(&amp;p-&gt;ar_addrs[(p-&gt;ar_hwlen*2) + p-&gt;ar_prlen])&nbsp;&nbsp; &nbsp;\/*\u8ba1\u7b97\u76ee\u6807\u534f\u8bae\u5730\u5740*\/<\/p>\n<p>\n\t\t#define&nbsp;&nbsp; &nbsp;MAXHWALEN&nbsp;&nbsp; &nbsp;EP_ALEN&nbsp;&nbsp; &nbsp;\/* \u4ee5\u592a\u7f51\u5730\u5740\u6700\u5927\u957f\u5ea6&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;MAXPRALEN&nbsp;&nbsp; &nbsp;IP_ALEN&nbsp;&nbsp; &nbsp;\/* IP \u5730\u5740\u6700\u5927\u957f\u5ea6&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t#define ARP_HLEN&nbsp;&nbsp; &nbsp;8&nbsp;&nbsp; &nbsp;\/* ARP\u534f\u8bae\u5934\u957f\u5ea6&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t#define&nbsp;&nbsp; &nbsp;ARP_TSIZE&nbsp;&nbsp; &nbsp;50&nbsp;&nbsp; &nbsp;\/*&nbsp; ARP\u7f13\u5b58\u5927\u5c0f&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;ARP_QSIZE&nbsp;&nbsp; &nbsp;10&nbsp;&nbsp; &nbsp;\/*&nbsp; ARP\u534f\u8bae\u7aef\u53e3\u961f\u5217\u7684\u5927\u5c0f&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t\/* \u7f13\u5b58\u8d85\u65f6 cache timeouts *\/<\/p>\n<p>\t\t#define ARP_TIMEOUT&nbsp;&nbsp; &nbsp;600&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/* 10 minutes&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;ARP_INF&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;0x7fffffff&nbsp;&nbsp; &nbsp;\/* &ldquo;\u65e0\u9650&rdquo;\u8d85\u65f6\u503c &quot;infinite&quot; timeout value&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;ARP_RESEND&nbsp;&nbsp; &nbsp;1&nbsp;&nbsp; &nbsp;\/* \u5982\u679c\u6ca1\u6709\u57281\u79d2\u5185\u56de\u590d,\u91cd\u65b0\u53d1\u9001&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;ARP_MAXRETRY&nbsp;&nbsp; &nbsp;4&nbsp;&nbsp; &nbsp;\/* \u591a\u5c11\u79d2\u540e\u653e\u5f03\uff1f\uff1f give up after ~30 seconds&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\tstruct&nbsp;&nbsp; &nbsp;arpentry {&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/* ARP\u7f13\u5b58\u4e2d\u7684\u6761\u76ee\u683c\u5f0f&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;short&nbsp;&nbsp; &nbsp;ae_state;&nbsp;&nbsp; &nbsp;\/* \u672c\u6761\u76ee\u72b6\u6001\uff08\u89c1\u4e0b\u6587\uff09&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;short&nbsp;&nbsp; &nbsp;ae_hwtype;&nbsp;&nbsp; &nbsp;\/* \u786c\u4ef6\u7c7b\u578b&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;short&nbsp;&nbsp; &nbsp;ae_prtype;&nbsp;&nbsp; &nbsp;\/* \u534f\u8bae\u7c7b\u578b&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ae_hwlen;&nbsp;&nbsp; &nbsp;\/* \u786c\u4ef6\u5730\u5740\u7684\u957f\u5ea6&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;char&nbsp;&nbsp; &nbsp;ae_prlen;&nbsp;&nbsp; &nbsp;\/* \u534f\u8bae\u5730\u5740\u7684\u957f\u5ea6&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct netif *ae_pni;&nbsp;&nbsp; &nbsp;\/* \u6307\u5411\u63a5\u53e3\u7ed3\u6784\u4f53\u7684\u6307\u9488&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;ae_queue;&nbsp;&nbsp; &nbsp;\/* \u961f\u5217\u7684\u6570\u636e\u5305\u5730\u5740&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;ae_attempts;&nbsp;&nbsp; &nbsp;\/* \u91cd\u8bd5\uff0c\u5230\u76ee\u524d\u4e3a\u6b62 number of retries so far&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;ae_ttl;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/* \u751f\u5b58\u65f6\u95f4&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_char&nbsp;&nbsp; &nbsp;ae_hwa[MAXHWALEN];&nbsp;&nbsp; &nbsp;\/* \u786c\u4ef6\u5730\u5740 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;u_char&nbsp;&nbsp; &nbsp;ae_pra[MAXPRALEN];&nbsp;&nbsp; &nbsp;\/* \u534f\u8bae\u5730\u5740 &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t};<\/p>\n<p>\t\t#define&nbsp;&nbsp; &nbsp;AS_FREE&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;0&nbsp;&nbsp; &nbsp;\/* \u8868\u9879\u7a7a\u95f2&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;AS_PENDING&nbsp;&nbsp; &nbsp;1&nbsp;&nbsp; &nbsp;\/* \u8868\u9879\u4f7f\u7528\u4e2d\uff0c\u4f46\u672a\u7ed1\u5b9a&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\t#define&nbsp;&nbsp; &nbsp;AS_RESOLVED&nbsp;&nbsp; &nbsp;2&nbsp;&nbsp; &nbsp;\/* \u8868\u9879\u6b63\u786e\u7ed1\u5b9a &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t\/* RARP\u53d8\u91cf *\/<\/p>\n<p>\t\textern int&nbsp;&nbsp; &nbsp;rarppid;&nbsp;&nbsp; &nbsp;\/* \u8fdb\u7a0bID\u4e3aRARP\u7b49\u5f85\u7b54\u590d&nbsp;&nbsp; &nbsp;*\/<br \/>\n\t\textern int&nbsp;&nbsp; &nbsp;rarpsem;&nbsp;&nbsp; &nbsp;\/* RARP\u670d\u52a1\u83b7\u53d6\u4fe1\u53f7\u91cf&nbsp;&nbsp; &nbsp;*\/<\/p>\n<p>\t\t\/*&nbsp; ARP\u534f\u8bae\u7684\u53d8\u91cf *\/<\/p>\n<p>\t\textern struct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp;arptable[ARP_TSIZE];<\/p>\n<p>\t\t\/*&nbsp; ARP\u534f\u8bae\u51fd\u6570\u58f0\u660e *\/<\/p>\n<p>\t\tint&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp; arp_in(struct netif *, struct ep *);<br \/>\n\t\tstruct arpentry *arpfind(u_char *, u_short, struct netif *);<br \/>\n\t\tstruct arpentry *arpadd(struct netif *, struct arp *);<\/p>\n<\/blockquote>\n<hr \/>\n<p>2. \u641c\u7d22ARP\u9ad8\u901f\u7f13\u5b58<\/p>\n<blockquote>\n<p>\/* arpfind.c &#8211; arpfind *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpfind &#8211; find an ARP entry given a protocol address and interface<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tstruct arpentry *<br \/>\n\t\tarpfind(u_char *pra, u_short prtype, struct netif *pni)&nbsp;&nbsp; &nbsp;\/*\u53c2\u6570:\u534f\u8bae\u5730\u5740\uff0c\u534f\u8bae\u7c7b\u578b\uff0c\u63a5\u53e3\u7ed3\u6784\u6307\u9488*\/<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct arpentry&nbsp;&nbsp; &nbsp;*pae;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u5b9a\u4e49ARP\u7f13\u5b58\u7ed3\u6784\u4f53\u6307\u9488*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;i;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;for (i=0; i&lt;ARP_TSIZE; ++i) {&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u904d\u5386ARP\u7684\u7f13\u5b58*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae = &amp;arptable[i];&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u7f13\u5b58\u6570\u7ec4*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_state == AS_FREE)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u7f13\u5b58\u4e3a\u7a7a\u95f2\u63a5\u627e\u4e0b\u4e00\u4e2a*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;continue;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_prtype == prtype &amp;&amp;&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; pae-&gt;ae_pni == pni &amp;&amp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; BLKEQU(pae-&gt;ae_pra, pra, pae-&gt;ae_prlen))<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return pae;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u5982\u679c\u7f13\u5b58\u4e2d\u7684\u534f\u8bae\u7c7b\u578b\u4e0e\u53c2\u6570\u76f8\u540c\uff0c\u5e76\u4e14\u63a5\u53e3\u4e0e\u534f\u8bae\u5730\u5740\u5168\u76f8\u540c\uff0c\u5219\u8fd4\u56de\u8fd9\u4e2aARP\u6761\u76ee\u7684\u6307\u9488\u3002BLKEQU\u7684\u5b9a\u4e49 #define&nbsp;&nbsp;&nbsp; BLKEQU(b1, b2, len)&nbsp;&nbsp;&nbsp; (!memcmp((b1), (b2), len))*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return 0;<br \/>\n\t\t}<br \/>\n\t\t&nbsp;<\/p>\n<\/blockquote>\n<hr \/>\n<p>3. ARP\u8bf7\u6c42\u5e7f\u64ad\u5206\u7ec4<\/p>\n<blockquote>\n<p>\/* arpsend.c &#8211; arpsend *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpsend &#8211; broadcast an ARP request<br \/>\n\t\t&nbsp;*&nbsp;&nbsp; &nbsp;N.B. Assumes interrupts disabled<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tint<br \/>\n\t\tarpsend(struct arpentry *pae)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u6307\u5411ARP\u8868\u9879\u7684\u6307\u9488*\/<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;netif&nbsp;&nbsp; &nbsp;*pni = pae-&gt;ae_pni;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u6307\u5411\u63a5\u53e3\u7ed3\u6784\u6307\u9488*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;ep&nbsp;&nbsp; &nbsp;*pep;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u8d1e\u7ed3\u6784\u6307\u9488*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arp&nbsp;&nbsp; &nbsp;*parp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*ARP\u5206\u7ec4\u6307\u9488*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arplen;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;pep = (struct ep *) getbuf(Net.netpool);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u4e3a\u5206\u7ec4\u5206\u914d\u4e00\u4e2a\u7f13\u5b58\u533a*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if ((int)pep == SYSERR)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return SYSERR;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(pep-&gt;ep_dst, pni-&gt;ni_hwb.ha_addr, pae-&gt;ae_hwlen);\/*\u76ee\u7684\u5730\u64ad\u4e3a\u7269\u7406\u5e7f\u64ad\u5730\u5740*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pep-&gt;ep_type = EPT_ARP;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u5e27\u7c7b\u578b*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pep-&gt;ep_order = EPO_NET;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u7f51\u7edc\u5de5\u4f5c\u5c42*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/*\u586b\u5199ARP\u5305*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp = (struct arp *) pep-&gt;ep_data;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u4ee5\u592a\u7f51\u5e27\u4e2dARP\u7684\u6570\u636e*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_hwtype = hs2net(pae-&gt;ae_hwtype);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u786c\u4ef6\u7c7b\u578b*\/&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_prtype = hs2net(pae-&gt;ae_prtype);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u534f\u8bae\u7c7b\u578b*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_hwlen = pae-&gt;ae_hwlen;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u786c\u4ef6\u5730\u5740\u957f\u5ea6*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_prlen = pae-&gt;ae_prlen;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u534f\u8bae\u5730\u5740\u957f\u5ea6*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_op = hs2net(AR_REQUEST);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u64cd\u4f5c\u5b57\u6bb5\uff0c\u8bf7\u6c42*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(SHA(parp), pni-&gt;ni_hwa.ha_addr, pae-&gt;ae_hwlen);&nbsp;&nbsp; &nbsp;\/*\u53d1\u9001\u65b9\u786c\u4ef6\u5730\u5740*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(SPA(parp), &amp;pni-&gt;ni_ip, pae-&gt;ae_prlen);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u53d1\u9001\u65b9\u534f\u8bae\u5730\u5740*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memset(THA(parp), 0, pae-&gt;ae_hwlen);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u76ee\u6807\u786c\u4ef6\u5730\u5740\u6e05\u7a7a*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(TPA(parp), pae-&gt;ae_pra, pae-&gt;ae_prlen);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u76ee\u6807\u534f\u8bae\u5730\u5740*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;arplen = ARP_HLEN + 2*(parp-&gt;ar_hwlen + parp-&gt;ar_prlen);\/*ARP\u7684\u603b\u957f\u5ea6*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;write(pni-&gt;ni_dev, pep, EP_HLEN+arplen);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u53d1\u9001\u5206\u7ec4*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return OK;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>4. ARP\u8f93\u51fa\u8fc7\u7a0b<\/p>\n<blockquote>\n<p>\/* netwrite.c &#8211; netwrite *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\t#include &lt;ospf.h&gt;<\/p>\n<p>\t\tstruct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp;*arpalloc();<br \/>\n\t\tstruct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp; *arpfind(u_char *, u_short, struct netif *);<br \/>\n\t\tint&nbsp;&nbsp; &nbsp;arpsend(struct arpentry *);<br \/>\n\t\tint&nbsp;&nbsp; &nbsp;local_out(struct ep *);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u7528\u4e8e\u5c06\u76ee\u7684\u662f\u672c\u5730\u673a\u7684\u6570\u636e\u5305\u901a\u8fc7loopback \u53d1\u9001\u5230\u6307\u5b9a\u672c\u673a\u7aef\u53e3<\/p>\n<p>\t\t\/*#define&nbsp;&nbsp; &nbsp;DEBUG *\/<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* netwrite &#8211; write a packet on an interface, using ARP if needed<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tint<br \/>\n\t\tnetwrite(struct netif *pni, struct ep *pep, unsigned len)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arpentry &nbsp;&nbsp; &nbsp;*pae;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/ARP\u9879\u76ee\u6307\u9488<br \/>\n\t\t&nbsp;&nbsp; &nbsp;STATWORD&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;ps;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u72b6\u6001\u5b57<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;if (pni-&gt;ni_state != NIS_UP) {&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return SYSERR;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u63a5\u53e3\u672a\u6253\u5f00\u5219\u9000\u51fa<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pep-&gt;ep_len = len;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u5e27\u957f\u5ea6<br \/>\n\t\t#ifdef&nbsp;&nbsp; &nbsp;DEBUG&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;<br \/>\n\t\tif (pni != &amp;nif[NI_LOCAL])<br \/>\n\t\t{<br \/>\n\t\tstruct ip *pip = (struct ip *)pep-&gt;ep_data;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pip-&gt;ip_proto == IPT_OSPF) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;struct ospf *po = (struct ospf *)pip-&gt;ip_data;<br \/>\n\t\t\/*&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (po-&gt;ospf_type != T_HELLO) { *\/<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;kprintf(&quot;netwrite(pep %X, len %d)n&quot;, pep, len);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pdump(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t}<br \/>\n\t\t#endif&nbsp;&nbsp; &nbsp;\/* DEBUG *\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pni == &amp;nif[NI_LOCAL])&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u662f\u672c\u5730\u63a5\u53e3\uff0c\u7528local_out \u53d1\u9001<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return local_out(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;else if (isbrc(pep-&gt;ep_nexthop)) {&nbsp;&nbsp; &nbsp;\/*\u5426\u5219\uff0c\u9996\u5148\u68c0\u67e5\u4e0b\u4e00\u8df3\u662f\u5426\u662f\u5e7f\u64ad\u5730\u5740*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(pep-&gt;ep_dst, pni-&gt;ni_hwb.ha_addr, EP_ALEN);\/\/\u586b\u5199\u76ee\u7684\u7269\u7406\u5730\u5740\u4e3a\u5e7f\u64ad\u7269\u7406\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;write(pni-&gt;ni_dev, pep, len);&nbsp;&nbsp; &nbsp;\/\/\u53d1\u9001<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return OK;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/* \u5426\u5219\uff0c\u8be5\u534f\u8bae\u5730\u5740\u67e5\u627e&#8230; *\/<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;disable(ps);&nbsp;&nbsp; &nbsp;\/*\u5982\u679c\u4e0b\u4e00\u8df3\u5730\u5740\u4e0d\u662f\u5e7f\u64ad\u5730\u5740\uff0c\u5219\u5148\u5728arp \u7f13\u5b58\u8868\u4e2d\u67e5\u627e\u662f\u5426\u6709\u7ed1\u5b9a\u7684\u7269\u7406\u5730\u5740\uff0c\u6709\u5219\u76f4\u63a5\u53d1\u9001\uff0c\u6ca1\u6709\u5219\u5148\u505aarp \u5730\u5740\u7ed1\u5b9a\u3002*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae = arpfind((u_char *)&amp;pep-&gt;ep_nexthop, pep-&gt;ep_type, pni);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae &amp;&amp; pae-&gt;ae_state == AS_RESOLVED) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(pep-&gt;ep_dst, pae-&gt;ae_hwa, pae-&gt;ae_hwlen);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;restore(ps);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return write(pni-&gt;ni_dev, pep, len);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (IP_CLASSD(pep-&gt;ep_nexthop)) {&nbsp;&nbsp; &nbsp;\/*\u4e0b\u4e00\u8df3\u5730\u5740\u4e3ad \u7c7b\u5730\u5740\u5219\u76f4\u63a5\u8fd4\u56de*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;restore(ps);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return SYSERR;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae == 0) {&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u6ca1\u6709\u7ed1\u5b9a\uff0c\u505aarp \u89e3\u6790<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae = arpalloc();&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u5206\u914d\u7a7a\u95f4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_hwtype = AR_HARDWARE;&nbsp;&nbsp; &nbsp;\/\/\u786c\u4ef6\u7c7b\u578b<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_prtype = EPT_IP;&nbsp;&nbsp; &nbsp;\/\/\u534f\u8bae\u7c7b\u578b<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_hwlen = EP_ALEN;&nbsp;&nbsp; &nbsp;\/\/\u786c\u4ef6\u5730\u5740\u957f\u5ea6<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_prlen = IP_ALEN;&nbsp;&nbsp; &nbsp;\/\/\u534f\u8bae\u5730\u5740\u957f\u5ea6<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_pni = pni;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u63a5\u53e3<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_queue = EMPTY;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u961f\u5217\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(pae-&gt;ae_pra, &amp;pep-&gt;ep_nexthop, pae-&gt;ae_prlen);&nbsp;&nbsp; &nbsp;\/\/\u534f\u8bae\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_attempts = 0;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u91cd\u8bd5<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_ttl = ARP_RESEND;&nbsp;&nbsp; &nbsp;\/\/\u751f\u5b58\u65f6\u95f4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arpsend(pae);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u53d1\u9001<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/*\u5c06\u7b49\u5f85ARP\u7ed1\u5b9a\u7684\u6570\u636e\u5305\u5b58\u653e\u5728\u548cARP\u8868\u9879\u76f8\u5173\u7684\u961f\u5217\u4e2d\uff0c\u5982\u679c\u961f\u5217\u4e3a\u7a7a\uff0c\u5219\u5206\u914d\u4e00\u4e2a\u3002*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_queue == EMPTY)&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_queue = newq(ARP_QSIZE, QF_NOWAIT);&nbsp;&nbsp; &nbsp;\/\/\u5982\u6ca1\u6709\u961f\u5217\uff0c\u5efa\u7acb\u4e00\u4e2a\u65b0\u961f\u5217<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (enq(pae-&gt;ae_queue, pep, 0) &lt; 0)&nbsp;&nbsp; &nbsp;\/\/\u5c06\u5206\u7ec4\u653e\u5165\u961f\u5217\u4e2d, <br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;restore(ps);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return OK;&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u961f\u5217\u6ee1\uff0c\u5219\u5931\u4e22\u8fd9\u4e2a\u5206\u7ec4<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>5. ARP\u7684\u8f93\u5165\u5904\u7406<\/p>\n<blockquote>\n<p>\n\t\t\/* arpadd.c &#8211; arpadd *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\tstruct arpentry *arpalloc(void);<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpadd &#8211; Add a RESOLVED entry to the ARP cache<br \/>\n\t\t&nbsp;* &nbsp;&nbsp; &nbsp;N.B. Assumes interrupts disabled<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tstruct&nbsp;&nbsp; &nbsp;arpentry *<br \/>\n\t\tarpadd(struct netif *pni, struct arp *parp)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp;*pae;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/ARP\u7f13\u5b58\u8868\u9879\u6307\u9488<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;pae = arpalloc();&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u4e3a\u6307\u9488\u5206\u914d\u5185\u5b58\u7a7a\u95f4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u4ece\u6536\u5230\u7684ARP\u5305\u4e2d\u586b\u5199\u5230\u7f13\u5b58\u4e2d<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_hwtype = parp-&gt;ar_hwtype;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u786c\u4ef6\u7c7b\u578b&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_prtype = parp-&gt;ar_prtype;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u534f\u8bae\u7c7b\u578b<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_hwlen = parp-&gt;ar_hwlen;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u786c\u4ef6\u5730\u5740\u957f\u5ea6<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_prlen = parp-&gt;ar_prlen;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u534f\u8bae\u5730\u5740\u957f\u5ea6<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_pni = pni;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u63a5\u53e3<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_queue = EMPTY;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u961f\u5217\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(pae-&gt;ae_hwa, SHA(parp), parp-&gt;ar_hwlen);&nbsp;&nbsp; &nbsp;\/\/\u6e90\u7269\u7406\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;memcpy(pae-&gt;ae_pra, SPA(parp), parp-&gt;ar_prlen);&nbsp;&nbsp; &nbsp;\/\/\u6e90\u534f\u8bae\u5730\u5740<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_ttl = ARP_TIMEOUT;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u751f\u5b58\u65f6\u95f4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_state = AS_RESOLVED;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u8868\u9879\u7684\u72b6\u6001<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return pae;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>6. \u53d1\u9001\u7b49\u5f85\u53d1\u9001\u7684\u5206\u7ec4<\/p>\n<blockquote>\n<p>\n\t\t\/* arpqsend.c &#8211; arpqsend *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\tint netwrite(struct netif *, struct ep *, unsigned);<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpqsend &#8211; write packets queued waiting for an ARP resolution<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tvoid<br \/>\n\t\tarpqsend(struct arpentry *pae)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;ep&nbsp;&nbsp; &nbsp;*pep;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;netif&nbsp;&nbsp; &nbsp;*pni;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_queue == EMPTY)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u5f85\u53d1\u9001\u961f\u5217\u4e3a\u7a7a\u5219\u8fd4\u56de<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;pni = pae-&gt;ae_pni;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u63a5\u53e3<br \/>\n\t\t&nbsp;&nbsp; &nbsp;while (pep = (struct ep *)deq(pae-&gt;ae_queue))&nbsp;&nbsp; &nbsp;\/\/\u904d\u5386\u961f\u5217\u5e76\u53d1\u9001,\u4e3a\u7a7a\u5219\u91ca\u653e\u961f\u5217<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;netwrite(pni, pep, pep-&gt;ep_len);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;freeq(pae-&gt;ae_queue);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_queue = EMPTY;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>7. ARP\u8f93\u5165\u8fc7\u7a0b<\/p>\n<blockquote>\n<p>\n\t\t\/* arp_in.c &#8211; arp_in *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\tvoid arpqsend(struct arpentry *);<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*&nbsp; arp_in&nbsp; &#8211;&nbsp; handle ARP packet coming in from Ethernet network<br \/>\n\t\t&nbsp;*&nbsp;&nbsp; &nbsp;N.B. &#8211; Called by ni_in&#8211; SHOULD NOT BLOCK<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tint<br \/>\n\t\tarp_in(struct netif *pni, struct ep *pep)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arp&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;*parp = (struct arp *)pep-&gt;ep_data;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp;*pae;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arplen;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/*\u4ece\u7f51\u7edc\u5b57\u8282\u987a\u5e8f\u8f6c\u6362\u6210\u4e3b\u673a\u5b57\u8282\u987a\u5e8f*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_hwtype = net2hs(parp-&gt;ar_hwtype);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_prtype = net2hs(parp-&gt;ar_prtype);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;parp-&gt;ar_op = net2hs(parp-&gt;ar_op);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u786c\u4ef6\u7c7b\u578b\u6216\u534f\u8bae\u7c7b\u578b\u4e0d\u5339\u914d,\u5219\u4e22\u5145\u6b64\u5206\u7ec4\u5e76\u8fd4\u56de<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (parp-&gt;ar_hwtype != pni-&gt;ni_hwtype ||<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp; parp-&gt;ar_prtype != EPT_IP) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return OK;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679cARP\u8868\u9879\u4e2d\u6709\u6b64IP,\u5c31\u66f4\u65b0\u4e4b<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae = arpfind(SPA(parp), parp-&gt;ar_prtype, pni)) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(pae-&gt;ae_hwa, SHA(parp), pae-&gt;ae_hwlen);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_ttl = ARP_TIMEOUT;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u6b64\u5206\u7ec4\u4e0d\u662f\u53d1\u5f80\u6b64\u63a5\u53e3\u7684,\u5219\u4e22\u5f03\u4e4b<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (memcmp(TPA(parp), &amp;pni-&gt;ni_ip, IP_ALEN)) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return OK;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u662f\u53d1\u5f80\u672c\u63a5\u53e3\u5e76\u6ca1\u6709\u6b64\u8868\u9879,\u5219\u52a0\u5165\u4e00\u4e2a\u65b0\u8868\u9879<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae == 0)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae = arpadd(pni, parp);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u8868\u9879\u72b6\u6001\u4e3a\u6b63\u5728\u7ed1\u5b9a\u4e2d,\u5219\u53d1\u9001\u961f\u5217\u4e2d\u7684\u5206\u7ec4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_state == AS_PENDING) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_state = AS_RESOLVED;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arpqsend(pae);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u679c\u6536\u5230\u7684\u5206\u7ec4\u64cd\u4f5c\u7c7b\u578b\u4e3a\u8bf7\u6c42ARP,\u5219\u586b\u5199ARP\u5305\u5e76\u53d1\u9001,\u5426\u5219\u4e22\u5145\u5206\u7ec4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (parp-&gt;ar_op == AR_REQUEST) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;parp-&gt;ar_op = AR_REPLY;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(TPA(parp), SPA(parp), parp-&gt;ar_prlen);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(THA(parp), SHA(parp), parp-&gt;ar_hwlen);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(pep-&gt;ep_dst, THA(parp), EP_ALEN);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(SHA(parp), pni-&gt;ni_hwa.ha_addr,<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pni-&gt;ni_hwa.ha_len);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;memcpy(SPA(parp), &amp;pni-&gt;ni_ip, IP_ALEN);<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;parp-&gt;ar_hwtype = hs2net(parp-&gt;ar_hwtype);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;parp-&gt;ar_prtype = hs2net(parp-&gt;ar_prtype);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;parp-&gt;ar_op = hs2net(parp-&gt;ar_op);<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arplen = ARP_HLEN + 2*(parp-&gt;ar_prlen + parp-&gt;ar_hwlen);<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;write(pni-&gt;ni_dev, pep, arplen);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;} else<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return OK;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>8. ARP\u9ad8\u901f\u7f13\u5b58\u7684\u7ba1\u7406<\/p>\n<blockquote>\n<p>\/* arpalloc.c &#8211; arpalloc *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;proc.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\tvoid arpdq(struct arpentry *);<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpalloc &#8211; allocate an entry in the ARP table<br \/>\n\t\t&nbsp;*&nbsp;&nbsp; &nbsp;N.B. Assumes interrupts DISABLED<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tstruct arpentry *arpalloc()<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;static&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;aenext = 0;&nbsp;&nbsp; &nbsp;\/*\u9759\u6001\u53d8\u91cf*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;arpentry *pae;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;i;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u627e\u7a7a\u8868\u9879<br \/>\n\t\t&nbsp;&nbsp; &nbsp;for (i=0; i&lt;ARP_TSIZE; ++i) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (arptable[aenext].ae_state == AS_FREE)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;break;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;aenext = (aenext + 1) % ARP_TSIZE;&nbsp;&nbsp; &nbsp;\/\/\u5b9e\u73b0\u9759\u6001\u53d8\u91cf\u5faa\u73af\u8ba1\u6570<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae = &amp; arptable[aenext];<br \/>\n\t\t&nbsp;&nbsp; &nbsp;aenext = (aenext + 1) % ARP_TSIZE;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;\/\/\u5982\u6ca1\u6709\u7a7a\u8868\u9879,\u5219\u4f7f\u7528\u8fd9\u4e2a\u5f53\u524d\u7684\u8868\u9879,\u5224\u65ad\u4e3a\u4f7f\u7528\u4e2d\u4f46\u672a\u7ed1\u5b9a,\u5e76\u4e14\u6709\u961f\u5217,\u5982\u679c\u6709\u5219\u4e22\u5f03\u961f\u5217\u4e2d\u7684\u5206\u7ec4<br \/>\n\t\t&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_state == AS_PENDING &amp;&amp; pae-&gt;ae_queue &gt;= 0)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arpdq(pae);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_state = AS_PENDING;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;return pae;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>9. \u9ad8\u901f\u7f13\u5b58\u7684\u5b9a\u671f\u7ef4\u62a4\u7ba1\u7406<\/p>\n<blockquote>\n<p>\/* arptimer.c &#8211; arptimer *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\tvoid&nbsp;&nbsp; &nbsp;arpdq(struct arpentry *);<br \/>\n\t\tint&nbsp;&nbsp; &nbsp;arpsend(struct arpentry *);<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arptimer &#8211; Iterate through ARP cache, aging (possibly removing) entries<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*&nbsp;&nbsp; &nbsp;gran&nbsp;&nbsp; &nbsp;&#8211; time since last iteration<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tvoid<br \/>\n\t\tarptimer(int gran)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct arpentry *pae;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;STATWORD&nbsp;&nbsp; &nbsp;ps;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;i;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;disable(ps);&nbsp;&nbsp; &nbsp;\/* \u4e92\u65a5\u91cf *\/<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;for (i=0; i&lt;ARP_TSIZE; ++i) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if ((pae = &amp;arptable[i])-&gt;ae_state == AS_FREE)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;continue;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u7a7a\u95f2\u7684\u6761\u76ee*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_ttl == ARP_INF)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;continue; &nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u4e0d\u8d85\u65f6\u6c38\u4e45\u6761\u76ee*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if ((pae-&gt;ae_ttl -= gran) &lt;= 0)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u5bff\u547d\u4e3a0\u6216\u8d1f*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_state == AS_RESOLVED)&nbsp;&nbsp; &nbsp;\/*\u6761\u76ee\u7ed1\u5b9a\u4e2d\u4f46\u672a\u6b63\u786e*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_state = AS_FREE;&nbsp;&nbsp; &nbsp;\/*\u4ec5\u6539\u53d8\u72b6\u6001\u4e3a\u7a7a\u95f2*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;else if (++pae-&gt;ae_attempts &gt; ARP_MAXRETRY) {&nbsp;&nbsp; &nbsp;\/*\u8d85\u8fc7\u6700\u5927\u5e7f\u64ad\u6b21\u6570*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_state = AS_FREE;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arpdq(pae);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u6e05\u7a7a\u961f\u5217*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} else {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pae-&gt;ae_ttl = ARP_RESEND;&nbsp;&nbsp; &nbsp;\/*\u7b49\u4e8e\u91cd\u53d1\u65f6\u95f4*\/&nbsp;&nbsp; &nbsp;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arpsend(pae);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u91cd\u65b0\u5e7f\u64ad\u5206\u7ec4*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;restore(ps);<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>10. \u91ca\u653e\u961f\u5217\u4e2d\u7684\u5206\u7ec4<\/p>\n<blockquote>\n<p>\n\t\t\/* arpdq.c &#8211; arpdq *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;* arpdq &#8211; destroy an arp queue that has expired<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tvoid<br \/>\n\t\tarpdq(struct arpentry *pae)<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;ep&nbsp;&nbsp; &nbsp;*pep;<br \/>\n\t\t&nbsp;&nbsp; &nbsp;struct&nbsp;&nbsp; &nbsp;ip&nbsp;&nbsp; &nbsp;*pip;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;if (pae-&gt;ae_queue &lt; 0)&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/* \u961f\u5217\u4e3a\u7a7a,\u76f4\u63a5\u8fd4\u56de *\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;return;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;while (pep = (struct ep *)deq(pae-&gt;ae_queue)) {<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;if (gateway &amp;&amp; pae-&gt;ae_prtype == EPT_IP) {\/*\u672c\u673a\u662f\u7f51\u5173\u5e76\u4e14\u6570\u636e\u62a5\u4e3aIP\u6570\u636e\u62a5*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;pip = (struct ip *)pep-&gt;ep_data;&nbsp;&nbsp; &nbsp;\/\/\u751f\u6210ICMP&quot;\u76ee\u7684\u7ad9\u4e0d\u53ef\u8fbe&quot;\u4fe1\u606f<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;icmp(ICT_DESTUR, ICC_HOSTUR, pip-&gt;ip_src, pep, 0);<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;} else<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;freebuf(pep);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u91ca\u653e\u5e27<br \/>\n\t\t&nbsp;&nbsp; &nbsp;}<br \/>\n\t\t&nbsp;&nbsp; &nbsp;freeq(pae-&gt;ae_queue);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/\/\u91ca\u653e\u961f\u5217<br \/>\n\t\t&nbsp;&nbsp; &nbsp;pae-&gt;ae_queue = EMPTY;<br \/>\n\t\t}<\/p>\n<\/blockquote>\n<hr \/>\n<p>11. ARP\u521d\u59cb\u5316<\/p>\n<blockquote>\n<p>\/* arpinit.c &#8211; arpinit *\/<\/p>\n<p>\t\t#include &lt;conf.h&gt;<br \/>\n\t\t#include &lt;kernel.h&gt;<br \/>\n\t\t#include &lt;proc.h&gt;<br \/>\n\t\t#include &lt;network.h&gt;<\/p>\n<p>\t\t\/*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*&nbsp; arpinit&nbsp; &#8211;&nbsp; initialize data structures for ARP processing<br \/>\n\t\t&nbsp;*&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;<br \/>\n\t\t&nbsp;*\/<br \/>\n\t\tvoid arpinit()<br \/>\n\t\t{<br \/>\n\t\t&nbsp;&nbsp; &nbsp;int&nbsp;&nbsp; &nbsp;i;<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;rarpsem = screate(1);&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*\u521b\u5efa\u4e00\u4e2a\u4e0eRARP\u4e00\u8d77\u4f7f\u7528\u7684\u4e92\u65a5\u578b\u4fe1\u53f7\u91cf*\/<br \/>\n\t\t&nbsp;&nbsp; &nbsp;rarppid = BADPID;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;\/*RARP\u8fdb\u7a0b\u53f7\u521d\u59cb\u4e3a-1*\/<\/p>\n<p>\t\t&nbsp;&nbsp; &nbsp;for (i=0; i&lt;ARP_TSIZE; ++i)<br \/>\n\t\t&nbsp;&nbsp; &nbsp;&nbsp;&nbsp; &nbsp;arptable[i].ae_state = AS_FREE;&nbsp;&nbsp; &nbsp;\/*\u5c06\u72b6\u6001\u5168\u90e8\u7f6e\u4e3aAS_FREE*\/<br \/>\n\t\t}<\/p>\n<p>\t\tint&nbsp;&nbsp; &nbsp;rarpsem;<br \/>\n\t\tint&nbsp;&nbsp; &nbsp;rarppid;<\/p>\n<p>\t\tstruct&nbsp;&nbsp; &nbsp;arpentry&nbsp;&nbsp; &nbsp;arptable[ARP_TSIZE];&nbsp;&nbsp; &nbsp;\/*\u5b9a\u4e49ARP\u9ad8\u901f\u7f13\u5b58*\/<\/p>\n<\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>1. ARP\u9ad8\u901f\u7f13\u5b58\u7684\u6570\u636e\u7ed3\u6784 \/* arp.h &#8211; SHA, SPA, THA, TPA *\/  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[],"class_list":["post-556","post","type-post","status-publish","format-standard","hentry","category-linux-c"],"_links":{"self":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts\/556","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=556"}],"version-history":[{"count":0,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=\/wp\/v2\/posts\/556\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=556"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=556"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.kumouse.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=556"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}