water/index.html
2013-03-25 19:03:33 -07:00

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<h1>Water</h1>
<p>A simple TUN/TAP library written in native Go.</p>
<p class="view"><a href="https://github.com/songgao/water">View the Project on GitHub <small>songgao/water</small></a></p>
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<li><a href="https://github.com/songgao/water/zipball/master">Download <strong>ZIP File</strong></a></li>
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<li><a href="https://github.com/songgao/water">View On <strong>GitHub</strong></a></li>
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<section>
<h1>water</h1>
<p><code>water</code> is a native Go library for <a href="http://en.wikipedia.org/wiki/TUN/TAP">TUN/TAP</a> interfaces.</p>
<p><code>water</code> is designed to be simple and efficient. It</p>
<ul>
<li>wraps almost only syscalls and uses only Go standard types;</li>
<li>exposes standard interfaces; plays well with standard packages like <code>io</code>, <code>bufio</code>, etc..</li>
<li>does not handle memory management (allocating/destructing slice). It's up to user to decide how to deal with buffers; whether to use GC.</li>
</ul><p><code>water/waterutil</code> has some useful functions to interpret MAC farme headers and IP packet headers. It also contains some constants such as protocol numbers and ethernet frame types.</p>
<h2>Installation</h2>
<pre><code>go get -u github.com/songgao/water
go get -u github.com/songgao/water/waterutil
</code></pre>
<h2>Documentation</h2>
<p><a href="http://godoc.org/github.com/songgao/water">http://godoc.org/github.com/songgao/water</a></p>
<p><a href="http://godoc.org/github.com/songgao/water/waterutil">http://godoc.org/github.com/songgao/water/waterutil</a></p>
<h2>Example</h2>
<div class="highlight"><pre><span class="kn">package</span> <span class="nx">main</span>
<span class="kn">import</span> <span class="p">(</span>
<span class="s">"github.com/songgao/water"</span>
<span class="s">"github.com/songgao/water/waterutil"</span>
<span class="s">"fmt"</span>
<span class="p">)</span>
<span class="kd">const</span> <span class="nx">BUFFERSIZE</span> <span class="p">=</span> <span class="mi">1522</span>
<span class="kd">func</span> <span class="nx">main</span><span class="p">()</span> <span class="p">{</span>
<span class="nx">ifce</span><span class="p">,</span> <span class="nx">err</span> <span class="o">:=</span> <span class="nx">water</span><span class="p">.</span><span class="nx">NewTAP</span><span class="p">(</span><span class="s">""</span><span class="p">)</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"%v, %v\n\n"</span><span class="p">,</span> <span class="nx">err</span><span class="p">,</span> <span class="nx">ifce</span><span class="p">)</span>
<span class="nx">buffer</span> <span class="o">:=</span> <span class="nb">make</span><span class="p">([]</span><span class="kt">byte</span><span class="p">,</span> <span class="nx">BUFFERSIZE</span><span class="p">)</span>
<span class="k">for</span> <span class="p">{</span>
<span class="nx">_</span><span class="p">,</span> <span class="nx">err</span> <span class="p">=</span> <span class="nx">ifce</span><span class="p">.</span><span class="nx">Read</span><span class="p">(</span><span class="nx">buffer</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">err</span> <span class="o">!=</span> <span class="kc">nil</span> <span class="p">{</span>
<span class="k">break</span>
<span class="p">}</span>
<span class="nx">ethertype</span> <span class="o">:=</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">MACEthertype</span><span class="p">(</span><span class="nx">buffer</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">ethertype</span> <span class="o">==</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">IPv4</span> <span class="p">{</span>
<span class="nx">packet</span> <span class="o">:=</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">MACPayload</span><span class="p">(</span><span class="nx">buffer</span><span class="p">)</span>
<span class="k">if</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">IsIPv4</span><span class="p">(</span><span class="nx">packet</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"Source: %v [%v]\n"</span><span class="p">,</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">MACSource</span><span class="p">(</span><span class="nx">buffer</span><span class="p">),</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">IPv4Source</span><span class="p">(</span><span class="nx">packet</span><span class="p">))</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"Destination: %v [%v]\n"</span><span class="p">,</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">MACDestination</span><span class="p">(</span><span class="nx">buffer</span><span class="p">),</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">IPv4Destination</span><span class="p">(</span><span class="nx">packet</span><span class="p">))</span>
<span class="nx">fmt</span><span class="p">.</span><span class="nx">Printf</span><span class="p">(</span><span class="s">"Protocol: %v\n\n"</span><span class="p">,</span> <span class="nx">waterutil</span><span class="p">.</span><span class="nx">IPv4Protocol</span><span class="p">(</span><span class="nx">packet</span><span class="p">))</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
<span class="p">}</span>
</pre></div>
<p>This piece of code creates a <code>TAP</code> interface, and prints some header information for every IPv4 packet. After pull up the <code>main.go</code>, you'll need to bring up the interface and assign IP address. All of these need root permission.</p>
<div class="highlight"><pre>sudo go run main.go
</pre></div>
<div class="highlight"><pre>sudo ip link <span class="nb">set </span>dev tap0 up
sudo ip addr add 10.0.0.1/24 dev tap0
</pre></div>
<p>Now, try sending some ICMP broadcast message:</p>
<div class="highlight"><pre>ping -b 10.0.0.255
</pre></div>
<p>You'll see the <code>main.go</code> print something like:</p>
<pre><code>&lt;nil&gt;, &amp;{true 0xf84003f058 tap0}
Source: 42:35:da:af:2b:00 [10.0.0.1]
Destination: ff:ff:ff:ff:ff:ff [10.0.0.255]
Protocol: 1
Source: 42:35:da:af:2b:00 [10.0.0.1]
Destination: ff:ff:ff:ff:ff:ff [10.0.0.255]
Protocol: 1
Source: 42:35:da:af:2b:00 [10.0.0.1]
Destination: ff:ff:ff:ff:ff:ff [10.0.0.255]
Protocol: 1
</code></pre>
<h2>TODO</h2>
<ul>
<li>IPv6 Support in <code>waterutil</code>
</li>
<li>Darwin(Mac) Support</li>
</ul><h2>LICENSE</h2>
<p>GNU LESSER GENERAL PUBLIC LICENSE Version 3</p>
<h2>Alternatives</h2>
<p><code>tuntap</code>: <a href="https://code.google.com/p/tuntap/">https://code.google.com/p/tuntap/</a></p>
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