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pascal / winpcap example ... i don't get any packets
{$mode delphi}
program pcapdemo;
uses pcap, sysutils, crt;
procedure throw(msg:string; detail:pchar);
begin raise Exception.Create(msg + ': ' + detail)
end;
function IPv4ToStr(addr:dword) : string;
// this probably exists somewhere but i don't know where.
type asbytes = array[0..3] of byte;
var i, b : byte;
begin
for i := 0 to 3 do begin
result += intToStr(asbytes(addr)[i]);
if i < 3 then result += '.';
end;
end;
var
err : pchar;
cap : ppcap;
dev, devs : ppcap_if;
addr, mask : dword;
prog : Tbpf_program;
head : Tpcap_pkthdr;
pack : pchar;
filter : pchar = ''; //tcp port 80';
choice, count : word;
const
kPcapOptimize = 1;
kPcapNoOptimize = 0;
kPcapOK = 0;
kPCapError = -1;
kPcapPromiscuous = 1;
kSnaplen = 64; // chars to capture
kTimeout = 1000; // milliseconds
begin
err := stralloc(PCAP_ERRBUF_SIZE);
try
// name := pcap_lookupdev(err);
// if name = nil then throw('error looking up device', err);
if pcap_findalldevs(@devs, err) <> kPCapOK
then throw('error listing all devices', err);
{-- choose which device to monitor --}
dev := devs; count := 0;
repeat
writeln(count:3, ' ', dev^.description);
dev := dev^.next; inc(count);
until dev = nil;
if count = 0 then choice := 0
else begin
repeat write('which? (0-', count, ')'); readln(choice);
until (choice >= 0) and (choice < count);
dev := devs; count := 0;
while count < choice do begin
dev := dev^.next; inc(count);
end
end;
{-- set up the connection --------}
if pcap_lookupnet(dev^.name, @addr, @mask, err) <> kPCapOK
then throw('error looking up net details', err);
cap := pcap_open_live(dev^.name, ksnaplen, kPcapPromiscuous, kTimeout, err);
if cap = nil then throw('error opening live', err);
if pcap_compile(cap, @prog, filter, kPcapNoOptimize, mask) <> kPcapOK
then throw('error compiling program', pcap_geterr(cap));
if pcap_setfilter(cap, @prog) <> kPcapOK
then throw('error setting filter', pcap_geterr(cap));
writeln;
writeln('device : ', dev^.name, ' (', dev^.description, ')');
writeln('address: ', IPv4ToStr(addr));
writeln('filter : ', filter);
writeln;
writeln('listening...');
writeln('----------------------------------------------');
repeat
if pcap_next_ex(cap, @head, @pack) <> kPcapError
then writeln(head.len, ' ', pack); // <-- always 0 and empty string
until keypressed;
except
on e:exception do writeln(e.message)
end;
pcap_close(cap); pcap_freealldevs(devs);
readln;
end.
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