That looks perfect for what i need, but how would i actually set this up to print out the packet? I don't have enough networking knowledge to understand this to be honest. So if anyone can modify it for me, it would be greatly appreciated and save me ALOT of time.use IO::Socket; $hostname = $ARGV[0]; $defdomain = ".oog.org"; # default domain if not present @servers = qw(nameserver1 nameserver2 nameserver3); # name of the name + servers foreach $server (@servers) { &lookupaddress($hostname,$server); # populates %resul +ts } %inv = reverse %results; # invert the result hash if (scalar(keys %inv) > 1) { # see how many elements it has print "There is a discrepancy between DNS servers:\n"; use Data::Dumper; print Data::Dumper->Dump([\%results],["results"]),"\n"; } sub lookupaddress{ my($hostname,$server) = @_; my($qname,$rname,$header,$question,$lformat,@labels,$count); local($position,$buf); ### ### Construct the packet header ### $header = pack("n C2 n4", ++$id, # query id 1, # qr, opcode, aa, tc, rd fields (only rd set) 0, # rd, ra 1, # one question (qdcount) 0, # no answers (ancount) 0, # no ns records in authority section (nscount) 0); # no addtl rr's (arcount) # if we do not have any separators in the name of the host, # append the default domain if (index($hostname,'.') == -1) { $hostname .= $defdomain; } # construct the qname section of a packet (domain name in question +) for (split(/\./,$hostname)) { $lformat .= "C a* "; $labels[$count++]=length; $labels[$count++]=$_; } ### ### construct the packet question section ### $question = pack($lformat."C n2", @labels, 0, # end of labels 1, # qtype of A 1); # qclass of IN ### ### send the packet to the server and read the response ### $sock = new IO::Socket::INET(PeerAddr => $server, PeerPort => "domain", Proto => "udp"); $sock->send($header.$question); # we're using UDP, so we know the max packet size $sock->recv($buf,512); close($sock); # get the size of the response, since we're going to have to keep # track of where we are in the packet as we parse it (via $positio +n) $respsize = length($buf); ### ### unpack the header section ### ($id, $qr_opcode_aa_tc_rd, $rd_ra, $qdcount, $ancount, $nscount, $arcount) = unpack("n C2 n4",$buf); if (!$ancount) { warn "Unable to lookup data for $hostname from $server!\n"; return; } ### ### unpack the question section ### # question section starts 12 bytes in ($position,$qname) = &decompress(12); ($qtype,$qclass)=unpack('@'.$position.'n2',$buf); # move us forward in the packet to end of question section $position += 4; ### ### unpack all of the resource record sections ### for ( ;$ancount;$ancount--){ ($position,$rname) = &decompress($position); ($rtype,$rclass,$rttl,$rdlength)= unpack('@'.$position.'n2 N n',$buf); $position +=10; # this next line could be changed to use a more sophisticated # data structure, it currently picks the last rr returned + $results{$server}= join('.',unpack('@'.$position.'C'.$rdlength,$buf)); $position +=$rdlength; } } # handle domain information that is "compressed" as per RFC1035 # we take in the starting position of our packet parse and return # the name we found (after dealing with the compressed format pointer) # and the place we left off in the packet at the end of the name we fo +und sub decompress { my($start) = $_[0]; my($domain,$i,$lenoct); for ($i=$start;$i<=$respsize;) { $lenoct=unpack('@'.$i.'C', $buf); # get the length of label if (!$lenoct){ # 0 signals we are done with this sectio +n $i++; last; } if ($lenoct == 192) { # we've been handed a pointer, so recurs +e $domain.=(&decompress((unpack('@'.$i.'n',$buf) & 1023)))[1 +]; $i+=2; last } else { # otherwise, we have a plain label $domain.=unpack('@'.++$i.'a'.$lenoct,$buf).'.'; $i += $lenoct; } } return($i,$domain); }
In reply to Re: Replicating Net::DNS::Packet
by Anonymous Monk
in thread Replicating Net::DNS::Packet
by Anonymous Monk
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