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ZealOS/docs/Home/Net/Protocols/ICMP.ZC.html
TomAwezome 28ab32e893 Update documentation.
2021-12-28 22:49:58 -05:00

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<pre style="font-family:monospace;font-size:12pt">
<a name="l1"></a><span class=cF0>#</span><span class=cF1>define</span><span class=cF0> ICMP_TYPE_ECHO_REPLY </span><span class=cFE>0</span><span class=cF0>
<a name="l2"></a>#</span><span class=cF1>define</span><span class=cF0> ICMP_TYPE_ECHO_REQUEST </span><span class=cFE>8</span><span class=cF0>
<a name="l3"></a>#</span><span class=cF1>define</span><span class=cF0> ICMP_CODE_ECHO </span><span class=cFE>0</span><span class=cF0> </span><span class=cF2>// RFC 792: &quot;Echo or Echo Reply Message&quot;. 0 is the only code explicitly defined for Echo.</span><span class=cF0>
<a name="l4"></a>
<a name="l5"></a></span><span class=cF1>class</span><span class=cF0> CICMPHeader
<a name="l6"></a>{
<a name="l7"></a> </span><span class=cF1>U8</span><span class=cF0> type;
<a name="l8"></a> </span><span class=cF1>U8</span><span class=cF0> code;
<a name="l9"></a> </span><span class=cF9>U16</span><span class=cF0> checksum;
<a name="l10"></a>
<a name="l11"></a> </span><span class=cF9>U16</span><span class=cF0> identifier;
<a name="l12"></a> </span><span class=cF9>U16</span><span class=cF0> sequence_number;
<a name="l13"></a>};
<a name="l14"></a>
<a name="l15"></a>
<a name="l16"></a></span><span class=cF2>/*</span><span class=cF0> </span><span class=cF2>global variable containing last reply ICMP header received,</span><span class=cF0>
<a name="l17"></a> </span><span class=cF2>Ping() checks this to make ping report.</span><span class=cF0>
<a name="l18"></a></span><span class=cF2>*/</span><span class=cF0>
<a name="l19"></a>CICMPHeader icmp_reply;
<a name="l20"></a>
<a name="l21"></a>
<a name="l22"></a></span><span class=cF1>U0</span><span class=cF0> ICMPInit()
<a name="l23"></a>{
<a name="l24"></a> </span><span class=cF5>MemSet</span><span class=cF0>(&amp;icmp_reply, </span><span class=cFE>0</span><span class=cF0>, </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>);
<a name="l25"></a>}
<a name="l26"></a>
<a name="l27"></a>NetQueueInit;
<a name="l28"></a>
<a name="l29"></a></span><span class=cF9>U16</span><span class=cF0> ICMPChecksum(</span><span class=cF1>U8</span><span class=cF0> *buf, </span><span class=cF9>I64</span><span class=cF0> size)
<a name="l30"></a>{
<a name="l31"></a> </span><span class=cF9>U64</span><span class=cF0> i, sum = </span><span class=cFE>0</span><span class=cF0>;
<a name="l32"></a>
<a name="l33"></a> </span><span class=cF1>for</span><span class=cF0> (i = </span><span class=cFE>0</span><span class=cF0>; i &lt; size; i += </span><span class=cFE>2</span><span class=cF0>)
<a name="l34"></a> </span><span class=cF7>{</span><span class=cF0>
<a name="l35"></a> sum += *buf(</span><span class=cF9>U16</span><span class=cF0> *);
<a name="l36"></a> buf += </span><span class=cFE>2</span><span class=cF0>;
<a name="l37"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l38"></a>
<a name="l39"></a> </span><span class=cF1>if</span><span class=cF0> (size - i &gt; </span><span class=cFE>0</span><span class=cF0>)
<a name="l40"></a> sum += *buf;
<a name="l41"></a>
<a name="l42"></a> </span><span class=cF1>while</span><span class=cF0> (sum &gt;&gt; </span><span class=cFE>16</span><span class=cF0> != </span><span class=cFE>0</span><span class=cF0>)
<a name="l43"></a> sum = sum &amp; </span><span class=cFE>0xFFFF</span><span class=cF0> + sum &gt;&gt; </span><span class=cFE>16</span><span class=cF0>;
<a name="l44"></a>
<a name="l45"></a> </span><span class=cF1>return</span><span class=cF0> ~sum(</span><span class=cF9>U16</span><span class=cF0>);
<a name="l46"></a>
<a name="l47"></a>}
<a name="l48"></a>
<a name="l49"></a>
<a name="l50"></a></span><span class=cF1>U0</span><span class=cF0> ICMPReplySend(</span><span class=cF9>U32</span><span class=cF0> destination_ip_address,
<a name="l51"></a> </span><span class=cF9>U16</span><span class=cF0> identifier,
<a name="l52"></a> </span><span class=cF9>U16</span><span class=cF0> sequence_number,
<a name="l53"></a> </span><span class=cF9>U16</span><span class=cF0> request_checksum,
<a name="l54"></a> </span><span class=cF1>U8</span><span class=cF0> *payload,
<a name="l55"></a> </span><span class=cF9>I64</span><span class=cF0> length)
<a name="l56"></a>{
<a name="l57"></a> </span><span class=cF1>U8</span><span class=cF0> *icmp_frame;
<a name="l58"></a> </span><span class=cF9>I64</span><span class=cF0> de_index;
<a name="l59"></a> CICMPHeader *header;
<a name="l60"></a>
<a name="l61"></a> de_index = IPV4PacketAllocate(&amp;icmp_frame,
<a name="l62"></a> IP_PROTOCOL_ICMP,
<a name="l63"></a> IPV4AddressGet,
<a name="l64"></a> destination_ip_address,
<a name="l65"></a> </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0> + length);
<a name="l66"></a> </span><span class=cF1>if</span><span class=cF0> (de_index &lt; </span><span class=cFE>0</span><span class=cF0>)
<a name="l67"></a> </span><span class=cF7>{</span><span class=cF0>
<a name="l68"></a> NetErr(</span><span class=cF6>&quot;ICMP SEND REPLY: Failed to allocate IPV4 packet.&quot;</span><span class=cF0>);
<a name="l69"></a> </span><span class=cF1>return</span><span class=cF0>;
<a name="l70"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l71"></a>
<a name="l72"></a> header = icmp_frame;
<a name="l73"></a>
<a name="l74"></a> header-&gt;type = ICMP_TYPE_ECHO_REPLY;
<a name="l75"></a> header-&gt;code = </span><span class=cFE>0</span><span class=cF0>; </span><span class=cF2>// why is 0 okay?</span><span class=cF0>
<a name="l76"></a> header-&gt;checksum = </span><span class=cF5>EndianU16</span><span class=cF0>(</span><span class=cF5>EndianU16</span><span class=cF7>(</span><span class=cF0>request_checksum</span><span class=cF7>)</span><span class=cF0> + </span><span class=cFE>0x0800</span><span class=cF0>);
<a name="l77"></a> header-&gt;identifier = identifier;
<a name="l78"></a> header-&gt;sequence_number = sequence_number;
<a name="l79"></a> </span><span class=cF2>// TODO: header checksum is awful. Shrine says hack alert.</span><span class=cF0>
<a name="l80"></a>
<a name="l81"></a> </span><span class=cF5>MemCopy</span><span class=cF0>(icmp_frame + </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>, payload, length);
<a name="l82"></a>
<a name="l83"></a> IPV4PacketFinish(de_index);
<a name="l84"></a>}
<a name="l85"></a>
<a name="l86"></a></span><span class=cF1>U0</span><span class=cF0> ICMPRequestSend(</span><span class=cF9>U32</span><span class=cF0> destination_ip_address,
<a name="l87"></a> </span><span class=cF9>U16</span><span class=cF0> identifier,
<a name="l88"></a> </span><span class=cF9>U16</span><span class=cF0> sequence_number,
<a name="l89"></a> </span><span class=cF1>U8</span><span class=cF0> *payload,
<a name="l90"></a> </span><span class=cF9>I64</span><span class=cF0> length)
<a name="l91"></a>{
<a name="l92"></a> </span><span class=cF1>U8</span><span class=cF0> *icmp_frame;
<a name="l93"></a> </span><span class=cF9>I64</span><span class=cF0> de_index;
<a name="l94"></a> CICMPHeader *header;
<a name="l95"></a>
<a name="l96"></a> de_index = IPV4PacketAllocate(&amp;icmp_frame,
<a name="l97"></a> IP_PROTOCOL_ICMP,
<a name="l98"></a> IPV4AddressGet,
<a name="l99"></a> destination_ip_address,
<a name="l100"></a> </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0> + length);
<a name="l101"></a> </span><span class=cF1>if</span><span class=cF0> (de_index &lt; </span><span class=cFE>0</span><span class=cF0>)
<a name="l102"></a> </span><span class=cF7>{</span><span class=cF0>
<a name="l103"></a> NetErr(</span><span class=cF6>&quot;ICMP SEND REQUEST: Failed to allocate IPV4 packet.&quot;</span><span class=cF0>);
<a name="l104"></a> </span><span class=cF1>return</span><span class=cF0>;
<a name="l105"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l106"></a>
<a name="l107"></a> header = icmp_frame;
<a name="l108"></a>
<a name="l109"></a> header-&gt;type = ICMP_TYPE_ECHO_REQUEST;
<a name="l110"></a> header-&gt;code = </span><span class=cFE>0</span><span class=cF0>; </span><span class=cF2>// why is 0 okay?</span><span class=cF0>
<a name="l111"></a> header-&gt;checksum = </span><span class=cFE>0</span><span class=cF0>;
<a name="l112"></a> header-&gt;identifier = identifier;
<a name="l113"></a> header-&gt;sequence_number = sequence_number;
<a name="l114"></a>
<a name="l115"></a> </span><span class=cF5>MemCopy</span><span class=cF0>(icmp_frame + </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>, payload, length);
<a name="l116"></a>
<a name="l117"></a> header-&gt;checksum = ICMPChecksum(header, </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0> + length);
<a name="l118"></a>
<a name="l119"></a> IPV4PacketFinish(de_index);
<a name="l120"></a>}
<a name="l121"></a>
<a name="l122"></a></span><span class=cF9>I64</span><span class=cF0> ICMPHandler(CIPV4Packet *packet)
<a name="l123"></a>{
<a name="l124"></a> CICMPHeader *header;
<a name="l125"></a>
<a name="l126"></a> </span><span class=cF1>if</span><span class=cF0> (packet-&gt;length &lt; </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>)
<a name="l127"></a> </span><span class=cF7>{</span><span class=cF0>
<a name="l128"></a> NetErr(</span><span class=cF6>&quot;ICMP HANDLER: Caught wrong IPV4 length.&quot;</span><span class=cF0>);
<a name="l129"></a> </span><span class=cF1>return</span><span class=cF0> -</span><span class=cFE>1</span><span class=cF0>;
<a name="l130"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l131"></a>
<a name="l132"></a> header = packet-&gt;data;
<a name="l133"></a>
<a name="l134"></a> </span><span class=cF1>if</span><span class=cF0> (header-&gt;type == ICMP_TYPE_ECHO_REQUEST &amp;&amp; header-&gt;code == ICMP_CODE_ECHO)
<a name="l135"></a> </span><span class=cF7>{</span><span class=cF0>
<a name="l136"></a> ARPCachePut(packet-&gt;source_ip_address, packet-&gt;ethernet_frame-&gt;source_address);
<a name="l137"></a>
<a name="l138"></a> ICMPReplySend(packet-&gt;source_ip_address,
<a name="l139"></a> header-&gt;identifier,
<a name="l140"></a> header-&gt;sequence_number,
<a name="l141"></a> header-&gt;checksum,
<a name="l142"></a> packet-&gt;data + </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>, </span><span class=cF2>// Data payload at IPV4Packet data location after the ICMP header</span><span class=cF0>
<a name="l143"></a> packet-&gt;length - </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>);</span><span class=cF2>// Payload length is size of packet after dropping header.</span><span class=cF0>
<a name="l144"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l145"></a> </span><span class=cF1>else</span><span class=cF0> </span><span class=cF1>if</span><span class=cF0> (header-&gt;type == ICMP_TYPE_ECHO_REPLY &amp;&amp; header-&gt;code == ICMP_CODE_ECHO)
<a name="l146"></a> </span><span class=cF7>{</span><span class=cF0> </span><span class=cF2>// save the reply to the global ICMP reply header</span><span class=cF0>
<a name="l147"></a> </span><span class=cF5>MemCopy</span><span class=cF0>(&amp;icmp_reply, header, </span><span class=cF1>sizeof</span><span class=cF7>(</span><span class=cF0>CICMPHeader</span><span class=cF7>)</span><span class=cF0>);
<a name="l148"></a> </span><span class=cF7>}</span><span class=cF0>
<a name="l149"></a> </span><span class=cF1>else</span><span class=cF0>
<a name="l150"></a> NetWarn(</span><span class=cF6>&quot;ICMP HANDLER: Unhandled ICMP packet. type, code: 0x%X, 0x%X&quot;</span><span class=cF0>, header-&gt;type, header-&gt;code);
<a name="l151"></a>
<a name="l152"></a> NetLog(</span><span class=cF6>&quot;ICMP HANDLER: Exiting.&quot;</span><span class=cF0>);
<a name="l153"></a>
<a name="l154"></a> </span><span class=cF1>return</span><span class=cF0> </span><span class=cFE>0</span><span class=cF0>;
<a name="l155"></a>}
<a name="l156"></a>
<a name="l157"></a>ICMPInit;</span></pre></body>
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