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<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>You are absolutely right. The
received array was the wrong item of the two. Following your suggestion,
I changed my ref int[] for a ref IntPtr and I now receive two items, the other
one is DOCSIS (Data Over Cable Service Interface Specifications, <a
href="http://en.wikipedia.org/wiki/DOCSIS">http://en.wikipedia.org/wiki/DOCSIS</a>
for those interested) as I have a cable modem.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>The lesson I learned is : Marshal
everything that is not a single value type, even if it seems to work... Or work
partially… ^-^<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'>Thank you.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<div>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center tabindex=-1>
</span></font></div>
<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>From:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
winpcap-users-bounces@winpcap.org [mailto:winpcap-users-bounces@winpcap.org] <b><span
style='font-weight:bold'>On Behalf Of </span></b>Gianluca Varenni<br>
<b><span style='font-weight:bold'>Sent:</span></b> August 24, 2006 12:34<br>
<b><span style='font-weight:bold'>To:</span></b> winpcap-users@winpcap.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: [Winpcap-users]
Pcap_list_datalinks return bad number of links.</span></font><o:p></o:p></p>
</div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>I think that the marshalling you are doing with P/Invoke is
wrong.</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>I haven't tried it myself, but you should probably</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>1. declare the dlt_buf parameter as "ref IntPtr" (or out
IntPtr)</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>2. call pcap_list_datalinks</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>3. create a managed int array of size "result" </span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>4. use Marshal.Copy(<a
href="ms-help://MS.MSDNQTR.2003OCT.1033/cpref/html/frlrfsystemintptrclasstopic.htm"><font
size=3><span style='font-size:12.0pt'>IntPtr</span></font></a></span></font><b><span
style='font-weight:bold'> </span></b><i><span style='font-style:italic'><span
class=MsoHyperlink><u><font color=blue>source</font></u></span></span></i><b><span
style='font-weight:bold'>,</span></b><font size=2><span style='font-size:10.0pt'><a
href="ms-help://MS.MSDNQTR.2003OCT.1033/cpref/html/frlrfsystemint32classtopic.htm"><font
size=3><span style='font-size:12.0pt'>int</span></font></a></span></font><b><span
style='font-weight:bold'>[] </span></b><i><span style='font-style:italic'><span
class=MsoHyperlink><u><font color=blue>destination</font></u></span></span></i><b><span
style='font-weight:bold'>,</span></b><font size=2><span style='font-size:10.0pt'><a
href="ms-help://MS.MSDNQTR.2003OCT.1033/cpref/html/frlrfsystemint32classtopic.htm"><font
size=3><span style='font-size:12.0pt'>int</span></font></a></span></font><b><span
style='font-weight:bold'> </span></b><i><span style='font-style:italic'><span
class=MsoHyperlink><u><font color=blue>startIndex</font></u></span></span></i><b><span
style='font-weight:bold'>,</span></b><font size=2><span style='font-size:10.0pt'><a
href="ms-help://MS.MSDNQTR.2003OCT.1033/cpref/html/frlrfsystemint32classtopic.htm"><font
size=3><span style='font-size:12.0pt'>int</span></font></a></span></font><b><span
style='font-weight:bold'> </span></b><em><i><u><font color=blue
face="Times New Roman"><span style='color:blue'>length</span></font></u></i></em><strong><b><font
face="Times New Roman">) to copy from the unmanaged pointer dlt_buf to the
managed int array.</font></b></strong><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>Have a nice day</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=2 face="Times New Roman"><span style='font-size:
10.0pt'>GV</span></font><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'> <o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid black 1.5pt;padding:0cm 0cm 0cm 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>----- Original Message ----- <o:p></o:p></span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='background:#E4E4E4'><b><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial;font-weight:bold'>From:</span></font></b><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:steve.a.beaudoin@gmail.com" title="steve.a.beaudoin@gmail.com">Steve
Beaudoin</a> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>To:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> <a
href="mailto:winpcap-users@winpcap.org" title="winpcap-users@winpcap.org">winpcap-users@winpcap.org</a>
<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Sent:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> Thursday, August
24, 2006 5:32 AM<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>Subject:</span></font></b><font size=2
face=Arial><span style='font-size:10.0pt;font-family:Arial'> [Winpcap-users]
Pcap_list_datalinks return bad number of links.<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Hi,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
I am developing a winpcap library in C# with visual studio 2005 (and using the
version 3.1 of winpcap) and the pcap_list_datalinks function return the value
2, indicating the number of datalinks it found, but the array return only one
element. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
I declared the import with this :<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
<font color=green><span style='color:green'>// WinPCap : int
pcap_list_datalinks(pcap_t *p, int **dlt_buf)<o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
[<font color=teal><span style='color:teal'>DllImport</span></font>(<font
color=maroon><span style='color:maroon'>"wpcap.dll"</span></font>,CharSet=<font
color=teal><span style='color:teal'>CharSet</span></font>.Ansi)]<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
<font color=blue><span style='color:blue'>internal</span></font> <font
color=blue><span style='color:blue'>extern</span></font> <font color=blue><span
style='color:blue'>static</span></font> <font color=blue><span
style='color:blue'>int</span></font> pcap_list_datalinks(<font color=teal><span
style='color:teal'>IntPtr</span></font> pcapT, <font color=blue><span
style='color:blue'>ref</span></font> <font color=blue><span style='color:blue'>int</span></font>[]
dlt_buf);</span></font><font size=1 face="OCR A Extended"><span
style='font-size:8.0pt;font-family:"OCR A Extended"'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended"'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
And the code to retrieve the links is :<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
<font color=teal><span style='color:teal'>IntPtr</span></font>
pcapT=OpenDevice(Target,Auth);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
<font color=blue><span style='color:blue'>int</span></font>[] links=<font
color=blue><span style='color:blue'>new</span></font> <font color=blue><span
style='color:blue'>int</span></font>[] {};<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=1 face="OCR A Extended"><span style='font-size:
8.0pt;font-family:"OCR A Extended";background:white'>
<font color=blue><span style='color:blue'>int</span></font> result=<font
color=teal><span style='color:teal'>NativeMethods</span></font>.pcap_list_datalinks(pcapT,<font
color=blue><span style='color:blue'>ref</span></font> links);</span></font><font
size=2 face=Arial><span style='font-size:10.0pt;font-family:Arial'> <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
The value return into result is 2, but the links array only have one value (1
for Ethernet).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
The detailed information returned by ethereal for the same network adapter
(path : capture->interfaces->details) return only one media supported (I
suppose this is the name they use for datalink).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
I first thought it was because I used 32bits integer for my array, but the
symptoms are the same with 16bits bytes.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
So, either the returned value is wrong, or I’m missing a datalink in my
array, or I’m doing something wrong in the code.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>
Someone have an idea before I dig into the winpcap source code?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<div class=MsoNormal align=center style='text-align:center'><font size=3
face="Times New Roman"><span style='font-size:12.0pt'>
<hr size=2 width="100%" align=center>
</span></font></div>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'>_______________________________________________<br>
Winpcap-users mailing list<br>
Winpcap-users@winpcap.org<br>
https://www.winpcap.org/mailman/listinfo/winpcap-users<o:p></o:p></span></font></p>
</blockquote>
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