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<div class=Section1>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'>Hi,<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'>I am trying to
receive packets using pcap_next_ex(), but for some reason I keep getting a
timeout. I know that packets are coming into the machine because I can
see them via WinDump. The odd part is that when I run WinDump
concurrently with my test application, I start to see packets in the test app
(as well as in WinDump). But without WinDump, I get no packets on the
test app at all.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'>I am guessing that
there is something I need to do to “start” the packet driver
capturing, although I thought that’s what pcap_open_live does, so I’m
not quite sure on that.<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'>My code so far is
a fairly liberal sampling of the pktdump_ex example:<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:green'>/* Open the adapter */<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>if</span> ((m_pSessionHandle =
pcap_open_live(m_pReceiveDevice->name, <span
style='color:green'>// name of the device<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> 65536, <span
style='color:green'>// 65536 means the whole packet will be captured.<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> 0, <span
style='color:green'>// non promiscuous mode (nonzero means promiscuous)<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> 1000, <span
style='color:green'>// read timeout<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> errbuf <span
style='color:green'>// error buffer</span>)) == NULL)<span style='color:green'><o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> //
Error code<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> std::cout << <span
style='color:#A31515'>"Filter: "</span> << m_strFilter <<
std::endl;<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>if</span> ( !m_strFilter.empty() )<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> bpf_u_int32
NetMask = 0;<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>struct</span> bpf_program fcode;<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:green'>//compile the filter<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>if</span>(pcap_compile(m_pSessionHandle, &fcode, <span
style='color:blue'>const_cast</span><<span style='color:blue'>char</span>*>(m_strFilter.c_str()),
1, NetMask) < 0)<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> //
Error code<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:green'>//set the filter<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>if</span>(pcap_setfilter(m_pSessionHandle, &fcode)<0)<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> //
Error code<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:green'>/* At this point, we don't need the device list any more.
Free it */<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> pcap_freealldevs(alldevs);<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'>And later on:<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>while</span>((res = pcap_next_ex( m_pSessionHandle,
&header, &pkt_data)) >= 0)<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>if</span>(res == 0)<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> {<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:green'>/* Timeout elapsed */<o:p></o:p></span></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> OutputDebugString(L<span
style='color:#A31515'>"No packets!\n"</span>);<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> <span
style='color:blue'>continue</span>;<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal style='margin-left:36.0pt;text-indent:36.0pt;text-autospace:
none'><span style='font-size:10.0pt;font-family:"Courier New"'>//…<o:p></o:p></span></p>
<p class=MsoNormal style='text-autospace:none'><span style='font-size:10.0pt;
font-family:"Courier New"'> }<o:p></o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<p class=MsoNormal><span lang=EN-US style='font-size:11.0pt'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:dotted silver 1.0pt;padding:4.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#666666'>Ryan Fowler</span></b><span style='font-size:10.0pt;font-family:
"Arial","sans-serif";color:#666666'><br>
</span><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#666666'>Software Engineer</span><span style='font-family:"Times New Roman","serif"'><o:p></o:p></span></p>
<p class=MsoNormal style='mso-margin-top-alt:9.0pt;margin-right:0cm;margin-bottom:
9.0pt;margin-left:0cm'><b><span style='font-size:9.0pt;font-family:"Arial","sans-serif";
color:#F57F20'>Thomson Reuters</span></b><span style='font-family:"Times New Roman","serif"'>
<o:p></o:p></span></p>
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