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                <font color="#2040a0">cerr</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot;Unknown ICMP packet type &quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <strong>int</strong><font color="4444FF">(</font><font color="#2040a0">icmphdr</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">type</font><font color="4444FF">)</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font>
                        <font color="#008000">&quot; received&quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">endl</font><font color="4444FF">;</font>
            <font color="4444FF"><strong>}</strong></font>
            <strong>return</strong> <font color="4444FF">-</font><font color="#FF0000">1</font><font color="4444FF">;</font>
        <font color="4444FF"><strong>}</strong></font>
        <font color="#444444">// If &quot;TTL expired&quot;, fall through.  Next test will fail if we</font>
        <font color="#444444">// try it, so we need a way past it.</font>
    <font color="4444FF"><strong>}</strong></font>
    <strong>else</strong> <strong>if</strong> <font color="4444FF">(</font><font color="#2040a0">icmphdr</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">id</font> <font color="4444FF">!</font><font color="4444FF">=</font> <font color="4444FF">(</font><font color="#2040a0">USHORT</font><font color="4444FF">)</font><font color="#2040a0">GetCurrentProcessId</font><font color="4444FF">(</font><font color="4444FF">)</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font>
        <font color="#444444">// Must be a reply for another pinger running locally, so just</font>
        <font color="#444444">// ignore it.</font>
        <strong>return</strong> <font color="4444FF">-</font><font color="#FF0000">2</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>

    <font color="#444444">// Figure out how far the packet travelled</font>
    <strong>int</strong> <font color="#2040a0">nHops</font> <font color="4444FF">=</font> <strong>int</strong><font color="4444FF">(</font><font color="#FF0000">256</font> <font color="4444FF">-</font> <font color="#2040a0">reply</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">ttl</font><font color="4444FF">)</font><font color="4444FF">;</font>
    <strong>if</strong> <font color="4444FF">(</font><font color="#2040a0">nHops</font> <font color="4444FF">=</font><font color="4444FF">=</font> <font color="#FF0000">192</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font> 
        <font color="#444444">// TTL came back 64, so ping was probably to a host on the</font>
        <font color="#444444">// LAN -- call it a single hop.</font>
        <font color="#2040a0">nHops</font> <font color="4444FF">=</font> <font color="#FF0000">1</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>
    <strong>else</strong> <strong>if</strong> <font color="4444FF">(</font><font color="#2040a0">nHops</font> <font color="4444FF">=</font><font color="4444FF">=</font> <font color="#FF0000">128</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font>
        <font color="#444444">// Probably localhost</font>
        <font color="#2040a0">nHops</font> <font color="4444FF">=</font> <font color="#FF0000">0</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>

    <font color="#444444">// Okay, we ran the gamut, so the packet must be legal -- dump it</font>
    <font color="#2040a0">cout</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">endl</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">bytes</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot; bytes from &quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> 
            <font color="#2040a0">inet_ntoa</font><font color="4444FF">(</font><font color="#2040a0">from</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">sin_addr</font><font color="4444FF">)</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot;, icmp_seq &quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> 
            <font color="#2040a0">icmphdr</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">seq</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot;, &quot;</font><font color="4444FF">;</font>
    <strong>if</strong> <font color="4444FF">(</font><font color="#2040a0">icmphdr</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">type</font> <font color="4444FF">=</font><font color="4444FF">=</font> <font color="#2040a0">ICMP_TTL_EXPIRE</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font>
        <font color="#2040a0">cout</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot;TTL expired.&quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">endl</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>
    <strong>else</strong> <font color="4444FF"><strong>{</strong></font>
        <font color="#2040a0">cout</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">nHops</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot; hop&quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="4444FF">(</font><font color="#2040a0">nHops</font> <font color="4444FF">=</font><font color="4444FF">=</font> <font color="#FF0000">1</font> ? <font color="#008000">&quot;&quot;</font> <font color="4444FF">:</font> <font color="#008000">&quot;s&quot;</font><font color="4444FF">)</font><font color="4444FF">;</font>
        <font color="#2040a0">cout</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#008000">&quot;, time: &quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="4444FF">(</font><font color="#2040a0">GetTickCount</font><font color="4444FF">(</font><font color="4444FF">)</font> <font color="4444FF">-</font> <font color="#2040a0">icmphdr</font><font color="4444FF">-</font><font color="4444FF">&gt;</font><font color="#2040a0">timestamp</font><font color="4444FF">)</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font>
                <font color="#008000">&quot; ms.&quot;</font> <font color="4444FF">&lt;</font><font color="4444FF">&lt;</font> <font color="#2040a0">endl</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>

    <strong>return</strong> <font color="#FF0000">0</font><font color="4444FF">;</font>
<font color="4444FF"><strong>}</strong></font>
</pre>


<hr noshade size=1 color=#404040>

<h4 class=lmargin><a href="../examples/src/ip_checksum.cpp">ip_checksum.cpp</a></h4>

<pre>
<font color="#444444">/***********************************************************************
 ip_checksum.cpp - Calculates IP-style checksums on a block of data.
***********************************************************************/</font>

<font color="0000ff"><strong>#define WIN32_LEAN_AND_MEAN</strong></font>
<font color="0000ff"><strong>#include <font color="#008000">&lt;windows.h&gt;</font></strong></font>

<font color="#2040a0">USHORT</font> <font color="#2040a0">ip_checksum</font><font color="4444FF">(</font><font color="#2040a0">USHORT</font><font color="4444FF">*</font> <font color="#2040a0">buffer</font>, <strong>int</strong> <font color="#2040a0">size</font><font color="4444FF">)</font> 
<font color="4444FF"><strong>{</strong></font>
    <strong>unsigned</strong> <strong>long</strong> <font color="#2040a0">cksum</font> <font color="4444FF">=</font> <font color="#FF0000">0</font><font color="4444FF">;</font>
    
    <font color="#444444">// Sum all the words together, adding the final byte if size is odd</font>
    <strong>while</strong> <font color="4444FF">(</font><font color="#2040a0">size</font> <font color="4444FF">&gt;</font> <font color="#FF0000">1</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font>
        <font color="#2040a0">cksum</font> <font color="4444FF">+</font><font color="4444FF">=</font> <font color="4444FF">*</font><font color="#2040a0">buffer</font><font color="4444FF">+</font><font color="4444FF">+</font><font color="4444FF">;</font>
        <font color="#2040a0">size</font> <font color="4444FF">-</font><font color="4444FF">=</font> <strong>sizeof</strong><font color="4444FF">(</font><font color="#2040a0">USHORT</font><font color="4444FF">)</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>
    <strong>if</strong> <font color="4444FF">(</font><font color="#2040a0">size</font><font color="4444FF">)</font> <font color="4444FF"><strong>{</strong></font>
        <font color="#2040a0">cksum</font> <font color="4444FF">+</font><font color="4444FF">=</font> <font color="4444FF">*</font><font color="4444FF">(</font><font color="#2040a0">UCHAR</font><font color="4444FF">*</font><font color="4444FF">)</font><font color="#2040a0">buffer</font><font color="4444FF">;</font>
    <font color="4444FF"><strong>}</strong></font>

    <font color="#444444">// Do a little shuffling</font>
    <font color="#2040a0">cksum</font> <font color="4444FF">=</font> <font color="4444FF">(</font><font color="#2040a0">cksum</font> <font color="4444FF">&gt;</font><font color="4444FF">&gt;</font> <font color="#FF0000">16</font><font color="4444FF">)</font> <font color="4444FF">+</font> <font color="4444FF">(</font><font color="#2040a0">cksum</font> <font color="4444FF">&amp;</font> <font color="#FF0000">0xffff</font><font color="4444FF">)</font><font color="4444FF">;</font>
    <font color="#2040a0">cksum</font> <font color="4444FF">+</font><font color="4444FF">=</font> <font color="4444FF">(</font><font color="#2040a0">cksum</font> <font color="4444FF">&gt;</font><font color="4444FF">&gt;</font> <font color="#FF0000">16</font><font color="4444FF">)</font><font color="4444FF">;</font>
    
    <font color="#444444">// Return the bitwise complement of the resulting mishmash</font>
    <strong>return</strong> <font color="4444FF">(</font><font color="#2040a0">USHORT</font><font color="4444FF">)</font><font color="4444FF">(</font>~<font color="#2040a0">cksum</font><font color="4444FF">)</font><font color="4444FF">;</font>
<font color="4444FF"><strong>}</strong></font></pre>


<hr noshade size=1 color=#404040>

<h4 class=lmargin><a href="../examples/src/rawping.h">rawping.h</a></h4>

<pre>
<font color="#444444">/***********************************************************************
 rawping.h - Declares the types, constants and prototypes required to
    use the rawping.cpp module.
***********************************************************************/</font>

<font color="0000ff"><strong>#define WIN32_LEAN_AND_MEAN</strong></font>
<font color="0000ff"><strong>#include <font color="#008000">&lt;winsock2.h&gt;</font></strong></font>

<font color="#444444">// ICMP packet types</font>
<font color="0000ff"><strong>#define ICMP_ECHO_REPLY 0</strong></font>
<font color="0000ff"><strong>#define ICMP_DEST_UNREACH 3</strong></font>
<font color="0000ff"><strong>#define ICMP_TTL_EXPIRE 11</strong></font>
<font color="0000ff"><strong>#define ICMP_ECHO_REQUEST 8</strong></font>

<font color="#444444">// Minimum ICMP packet size, in bytes</font>
<font color="0000ff"><strong>#define ICMP_MIN 8</strong></font>

<font color="0000ff"><strong>#ifdef _MSC_VER</strong></font>
<font color="#444444">// The following two structures need to be packed tightly, but unlike</font>
<font color="#444444">// Borland C++, Microsoft C++ does not do this by default.</font>
<font color="0000ff"><strong>#pragma pack(1)</strong></font>
<font color="0000ff"><strong>#endif</strong></font>

<font color="#444444">// The IP header</font>
<strong>struct</strong> <font color="#2040a0">IPHeader</font> <font color="4444FF"><strong>{</strong></font>
    <font color="#2040a0">BYTE</font> <font color="#2040a0">h_len</font><font color="4444FF">:</font><font color="#FF0000">4</font><font color="4444FF">;</font>           <font color="#444444">// Length of the header in dwords</font>
    <font c