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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /><title>Handling Packets</title><meta name="generator" content="KompoZer" /><link rel="stylesheet" type="text/css" href="plt-doc.css" /></head><body>
<h2>Handling Packets</h2>
<h3>Class Packet</h3>
<p>Gives you access to fieds within (the captured part of) a packet. You will normally work on Packets returned from <span style="font-style: italic;">Trace.read_packet() </span> or a <span style="font-style: italic;">Trace iterator</span> (see Trace Handling), but you can create a new packet instance with <span style="font-style: italic;">packet()</span> (see below).</p><p>Note
that the Layer and Decode methods return None if their requested object
was not present in the packet, or was not completely captured.</p>
<table class="indent1">
<tbody>
<tr><td class="heading" colspan="2">Class Methods</td></tr>
<tr>
<td class="name methodwidth"><strong>packet()</strong><br />
</td>
<td class="name descriptionwidth"><em>Packet() -> aPacket</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description vspace1">Makes a new Python Packet. A
python-libtrace packet maintains a set of pointers into a libtrace
packet or a python-libtrace data object. In a newly-created
Packet, all such pointers are NULL.<br />
</td>
</tr>
</tbody></table>
<br /><br />
<table class="indent1">
<tbody>
<tr><td class="heading" colspan="2">Instance Methods</td></tr>
<tr>
<td class="name methodwidth"><strong>layer2</strong></td>
<td class="name descriptionwidth"><em>pkt.layer2 -</em><em><em>> aLayer2</em></em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets a Layer2 object from the packet; see Layers page</td>
</tr>
<tr>
<td class="name"><strong>layer3</strong></td>
<td class="name"><em>pkt.layer3 -> aLayer3</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets a Layer3 object from the packet; see Layers page<br />
</td>
</tr>
<tr>
<td class="name"><strong>transport</strong></td>
<td class="name"><em>pkt.transport -> aTransport</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">
Gets a Transport object from the packet; see Layers page<br />
</td>
</tr>
<tr>
<td class="name"><strong>ip</strong></td>
<td class="name"><em>pkt.ip -> anIP</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets an IPv4 header from the packet</td>
</tr>
<tr>
</tr><tr>
<td class="name"><strong>ip6</strong></td>
<td class="name"><em>pkt.ip6 -> anIP6</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets an IPv6 header from the packet</td>
</tr>
<tr>
</tr><tr>
<td class="name"><strong>tcp</strong></td>
<td class="name"><em>pkt.tcp-> aTCP</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets a TCP header from the packet</td>
</tr>
<tr>
<td class="name"><strong>tcp_payload</strong></td>
<td class="name"><em>pkt.tcp_payload -> aData</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets a TCP payload from the packet, or None if it wasn't TCP.<br />
tcp_payload.data returns a ByteArray of the data<br />
</td>
</tr>
<tr>
</tr><tr>
<td class="name"><strong>udp</strong></td>
<td class="name"><em>pkt.udp -> aUDP</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets a UDP header from the packet</td>
</tr>
<tr>
<td class="name"><strong>udp_payload</strong></td>
<td class="name"><em>pkt.udp_payload -> aData</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">
Gets a UDP payload from the packet, or None if it wasn't UDP.<br />
udp_payload.data returns a ByteArray of the data<br />
</td>
</tr>
<tr>
<td class="name"><strong>icmp</strong></td>
<td class="name"><em>pkt.icmp -> anICMP</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets an ICMP header from the packet</td>
</tr>
<tr>
<td class="name"><strong>icmp6</strong></td>
<td class="name"><em>pkt.icmp -> anICMP</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Gets an ICMP v6header from the packet</td>
</tr>
<tr>
<td style="vertical-align: top;"><br />
</td>
<td style="vertical-align: top;"><br />
</td>
</tr>
<tr>
<td class="name"><strong>apply_filter()</strong></td>
<td class="name"><em>pkt.apply_filter(aFilter) -> result</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Tests whether the current contents of the packet
match <span style="font-style: italic;">aFilter.</span>
<br /> Result is <span style="font-style: italic;">True</span> if the filter matches, <span style="font-style: italic;">False</span> if it doesn't, or <span style="font-style: italic;">None</span> if the filter was invalid
</td>
</tr>
</tbody></table>
<br />
<table>
</table><table class="indent1">
<tbody>
<tr><td class="heading" colspan="2">Instance Variables</td></tr>
<tr>
<td class="name"><strong>data</strong></td>
<td class="name"><em>pkt.data -> aByteArray </em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description vspace1">Byte array containing object's header and its following bytes.<br />
May be used for any python-libtrace object<br />
</td>
</tr>
<tr><td class="name methodwidth"><strong>time</strong></td><td class="name descriptionwidth"><em>pkt.time -> aTimeval</em></td></tr><tr><td><br />
</td><td class="description">Packet Arrival Time as a Python Time</td></tr><tr>
<td class="name"><strong>seconds</strong></td>
<td class="name descriptionwidth"><em>pkt.seconds -> aFloat</em> </td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Packet Arrival Time in Unix seconds (double) </td>
</tr>
<tr>
<td class="name"><strong>ts_sec<br /></strong></td>
<td class="name"><em>pkt.ts_sec -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">
Packet Arrival Time in Unix seconds (integer)</td>
</tr>
<tr>
<td class="name"><span style="font-weight: bold;">erf_time</span><strong /></td>
<td class="name"><em>pkt.erf_time -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description vspace1">Packet Arrival Time as a DAG ERF time (64-bit)
</td>
</tr>
<tr>
<td class="name"><strong>wire_len</strong></td>
<td class="name"><em>pkt.wire_len</em><em> -> anInteger</em> </td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Original size of packet on the wire
</td>
</tr>
<tr>
<td class="name"><strong>capture_len<em /></strong></td>
<td class="name"><em>pkt.capture_len -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Number of bytes captured; may be less than wire_len
</td>
</tr>
<tr>
<td class="name methodwidth"><strong>ethertype</strong></td>
<td class="name descriptionwidth"><em>internet.ethertype -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Ethertype for the packet that contained this object
</td>
</tr>
<tr>
<td class="name"><strong>linktype<br /></strong></td>
<td class="name"><em>pkt.linktype -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">Packet's link type; see Layer2 on Layers page for linktype values</td>
</tr>
<tr>
<td class="name"><strong>vlan_id<br /></strong></td>
<td class="name"><em>pkt.vlan_id -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">VLAN ID for packets with an 802.1Q VLAN tag, zero otherwise</td></tr>
<tr>
<td class="name"><strong>direction<br /></strong></td>
<td class="name"><em>pkt.direction -> anInteger</em></td>
</tr>
<tr>
<td><br />
</td>
<td class="description">'Direction' of packet, for traces from interfaces that support this, <br />e.g. ERF traces. Direction values are:<br />
<font size="-1">TRACE_DIR_INCOMING, TRACE_DIR_INCOMING and TRACE_DIR_OTHER</font>
</td></tr>
</tbody></table>
<p>
</p><table class="indent1">
<tbody>
<tr>
<td class="heading" colspan="2">Class <span style="font-style: italic;">Set</span> Method</td>
</tr>
<tr><td class="name methodwidth"><span style="font-weight: bold;">data=</span></td>
<td class="name descriptionwidth"><em>Packet.data = aByteArray</em></td>
</tr>
<tr>
<td><br />
</td><td class="vspace1">Overwrites the data bytes in a Data object
with bytes from a byte array. The byte array may not be longer than the
original data from the packet.</td></tr>
</tbody>
</table>
<br />
<p>Nevil Brownlee<br />Mon, 13 Apr 15 (NZST)</p>
</body></html>
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