Edit D:\app\Administrator\product\11.2.0\dbhome_1\sysman\admin\scripts\Net-DNS-0.48\lib\Net\DNS\Packet.pm
package Net::DNS::Packet; # # $Id: Packet.pm 01-nov-2004.16:03:31 afontana Exp $ # use strict; use vars qw(@ISA @EXPORT_OK $VERSION $AUTOLOAD); require Exporter; @ISA = qw(Exporter); @EXPORT_OK = qw(dn_expand); use Carp; use Net::DNS; use Net::DNS::Question; use Net::DNS::RR; $VERSION = (qw$LastChangedRevision: 102 $)[1]; =head1 NAME Net::DNS::Packet - DNS packet object class =head1 SYNOPSIS C<use Net::DNS::Packet;> =head1 DESCRIPTION A C<Net::DNS::Packet> object represents a DNS packet. =head1 METHODS =head2 new $packet = Net::DNS::Packet->new("example.com"); $packet = Net::DNS::Packet->new("example.com", "MX", "IN"); $packet = Net::DNS::Packet->new(\$data); $packet = Net::DNS::Packet->new(\$data, 1); # set debugging ($packet, $err) = Net::DNS::Packet->new(\$data); If passed a domain, type, and class, C<new> creates a packet object appropriate for making a DNS query for the requested information. The type and class can be omitted; they default to A and IN. If passed a reference to a scalar containing DNS packet data, C<new> creates a packet object from that data. A second argument can be passed to turn on debugging output for packet parsing. If called in array context, returns a packet object and an error string. The error string will only be defined if the packet object is undefined (i.e., couldn't be created). Returns B<undef> if unable to create a packet object (e.g., if the packet data is truncated).' =cut sub new { my $class = shift; my %self; $self{"compnames"} = {}; PARSE: { if (ref($_[0])) { my $data = shift; my $debug = shift || 0; #-------------------------------------------------------------- # Parse the header section. #-------------------------------------------------------------- print ";; HEADER SECTION\n" if $debug; $self{"header"} = Net::DNS::Header->new($data); unless (defined $self{"header"}) { return wantarray ? (undef, "header section incomplete") : undef; } $self{"header"}->print if $debug; my $offset = Net::DNS::HFIXEDSZ(); #-------------------------------------------------------------- # Parse the question/zone section. #-------------------------------------------------------------- if ($debug) { print "\n"; my $section = ($self{"header"}->opcode eq "UPDATE") ? "ZONE" : "QUESTION"; print ";; $section SECTION (", $self{"header"}->qdcount, " record", $self{"header"}->qdcount == 1 ? "" : "s", ")\n"; } $self{"question"} = []; foreach (1 .. $self{"header"}->qdcount) { my $qobj; ($qobj, $offset) = parse_question($data, $offset); unless (defined $qobj) { last PARSE if $self{"header"}->tc; return wantarray ? (undef, "question section incomplete") : undef; } push(@{$self{"question"}}, $qobj); if ($debug) { print ";; "; $qobj->print; } } #-------------------------------------------------------------- # Parse the answer/prerequisite section. #-------------------------------------------------------------- if ($debug) { print "\n"; my $section = ($self{"header"}->opcode eq "UPDATE") ? "PREREQUISITE" : "ANSWER"; print ";; $section SECTION (", $self{"header"}->ancount, " record", $self{"header"}->ancount == 1 ? "" : "s", ")\n"; } $self{"answer"} = []; foreach (1 .. $self{"header"}->ancount) { my $rrobj; ($rrobj, $offset) = parse_rr($data, $offset); unless (defined $rrobj) { last PARSE if $self{"header"}->tc; return wantarray ? (undef, "answer section incomplete") : undef; } push(@{$self{"answer"}}, $rrobj); $rrobj->print if $debug; } #-------------------------------------------------------------- # Parse the authority/update section. #-------------------------------------------------------------- if ($debug) { print "\n"; my $section = ($self{"header"}->opcode eq "UPDATE") ? "UPDATE" : "AUTHORITY"; print ";; $section SECTION (", $self{"header"}->nscount, " record", $self{"header"}->nscount == 1 ? "" : "s", ")\n"; } $self{"authority"} = []; foreach (1 .. $self{"header"}->nscount) { my $rrobj; ($rrobj, $offset) = parse_rr($data, $offset); unless (defined $rrobj) { last PARSE if $self{"header"}->tc; return wantarray ? (undef, "authority section incomplete") : undef; } push(@{$self{"authority"}}, $rrobj); $rrobj->print if $debug; } #-------------------------------------------------------------- # Parse the additional section. #-------------------------------------------------------------- if ($debug) { print "\n"; print ";; ADDITIONAL SECTION (", $self{"header"}->adcount, " record", $self{"header"}->adcount == 1 ? "" : "s", ")\n"; } $self{"additional"} = []; foreach (1 .. $self{"header"}->arcount) { my $rrobj; ($rrobj, $offset) = parse_rr($data, $offset); unless (defined $rrobj) { last PARSE if $self{"header"}->tc; return wantarray ? (undef, "additional section incomplete") : undef; } push(@{$self{"additional"}}, $rrobj); $rrobj->print if $debug; } } else { my ($qname, $qtype, $qclass) = @_; $qtype = "A" unless defined $qtype; $qclass = "IN" unless defined $qclass; $self{"header"} = Net::DNS::Header->new; $self{"header"}->qdcount(1); $self{"question"} = [ Net::DNS::Question->new($qname, $qtype, $qclass) ]; $self{"answer"} = []; $self{"authority"} = []; $self{"additional"} = []; } } # PARSE return wantarray ? ((bless \%self, $class), undef) : bless \%self, $class; } =head2 data $data = $packet->data; Returns the packet data in binary format, suitable for sending to a nameserver. =cut sub data { my $self = shift; #---------------------------------------------------------------------- # Flush the cache of already-compressed names. This should fix the bug # that caused this method to work only the first time it was called. #---------------------------------------------------------------------- $self->{"compnames"} = {}; #---------------------------------------------------------------------- # Get the data for each section in the packet. #---------------------------------------------------------------------- # Note that EDNS OPT RR data should inly be appended to the additional # section of the packet. TODO: Packet is dropped silently if is tried to # have it appended to one of the other section my $data = $self->{"header"}->data; foreach my $question (@{$self->{"question"}}) { $data .= $question->data($self, length $data); } foreach my $rr (@{$self->{"answer"}}) { $data .= $rr->data($self, length $data); } foreach my $rr (@{$self->{"authority"}}) { $data .= $rr->data($self, length $data); } foreach my $rr (@{$self->{"additional"}}) { $data .= $rr->data($self, length $data); } return $data; } =head2 header $header = $packet->header; Returns a C<Net::DNS::Header> object representing the header section of the packet. =cut sub header { my $self = shift; return $self->{"header"}; } =head2 question, zone @question = $packet->question; Returns a list of C<Net::DNS::Question> objects representing the question section of the packet. In dynamic update packets, this section is known as C<zone> and specifies the zone to be updated. =cut sub question { my $self = shift; return @{$self->{"question"}}; } sub zone { my $self = shift; $self->question(@_); } =head2 answer, pre, prerequisite @answer = $packet->answer; Returns a list of C<Net::DNS::RR> objects representing the answer section of the packet. In dynamic update packets, this section is known as C<pre> or C<prerequisite> and specifies the RRs or RRsets which must or must not preexist. =cut sub answer { return @{$_[0]->{'answer'}}; } sub pre { &answer } sub prerequisite { &answer } =head2 authority, update @authority = $packet->authority; Returns a list of C<Net::DNS::RR> objects representing the authority section of the packet. In dynamic update packets, this section is known as C<update> and specifies the RRs or RRsets to be added or delted. =cut sub authority { return @{$_[0]->{'authority'}}; } sub update { &authority } =head2 additional @additional = $packet->additional; Returns a list of C<Net::DNS::RR> objects representing the additional section of the packet. =cut sub additional { return @{$_[0]->{'additional'}}; } =head2 print $packet->print; Prints the packet data on the standard output in an ASCII format similar to that used in DNS zone files. =cut sub print { print $_[0]->string; } =head2 string print $packet->string; Returns a string representation of the packet. =cut sub string { my $self = shift; my ($qr, $rr, $section); my $retval = ""; if (exists $self->{"answerfrom"}) { $retval .= ";; Answer received from $self->{answerfrom} " . "($self->{answersize} bytes)\n;;\n"; } $retval .= ";; HEADER SECTION\n"; $retval .= $self->header->string; $retval .= "\n"; $section = ($self->header->opcode eq "UPDATE") ? "ZONE" : "QUESTION"; $retval .= ";; $section SECTION (" . $self->header->qdcount . " record" . ($self->header->qdcount == 1 ? "" : "s") . ")\n"; foreach $qr ($self->question) { $retval .= ";; " . $qr->string . "\n"; } $retval .= "\n"; $section = ($self->header->opcode eq "UPDATE") ? "PREREQUISITE" : "ANSWER"; $retval .= ";; $section SECTION (" . $self->header->ancount . " record" . ($self->header->ancount == 1 ? "" : "s") . ")\n"; foreach $rr ($self->answer) { $retval .= $rr->string . "\n"; } $retval .= "\n"; $section = ($self->header->opcode eq "UPDATE") ? "UPDATE" : "AUTHORITY"; $retval .= ";; $section SECTION (" . $self->header->nscount . " record" . ($self->header->nscount == 1 ? "" : "s") . ")\n"; foreach $rr ($self->authority) { $retval .= $rr->string . "\n"; } $retval .= "\n"; $retval .= ";; ADDITIONAL SECTION (" . $self->header->arcount . " record" . ($self->header->arcount == 1 ? "" : "s") . ")\n"; foreach $rr ($self->additional) { $retval .= $rr->string . "\n"; } return $retval; } =head2 answerfrom print "packet received from ", $packet->answerfrom, "\n"; Returns the IP address from which we received this packet. User-created packets will return undef for this method. =cut sub answerfrom { my $self = shift; $self->{"answerfrom"} = shift if @_; return exists $self->{"answerfrom"} ? $self->{"answerfrom"} : undef; } =head2 answersize print "packet size: ", $packet->answersize, " bytes\n"; Returns the size of the packet in bytes as it was received from a nameserver. User-created packets will return undef for this method (use C<< length $packet->data >> instead). =cut sub answersize { my $self = shift; $self->{"answersize"} = shift if @_; return exists $self->{"answersize"} ? $self->{"answersize"} : undef; } =head2 push $packet->push(pre => $rr); $packet->push(update => $rr); $packet->push(additional => $rr); $packet->push(update => $rr1, $rr2, $rr3); $packet->push(update => @rr); Adds RRs to the specified section of the packet. =cut sub push { my ($self, $section, @rr) = @_; my $rr; return unless $section; $section = lc $section; if (($section eq "prerequisite") || ($section eq "prereq")) { $section = "pre"; } if (($self->{"header"}->opcode eq "UPDATE") && (($section eq "pre") || ($section eq "update")) ) { my $zone_class = ($self->zone)[0]->zclass; foreach $rr (@rr) { unless ($rr->class eq "NONE" || $rr->class eq "ANY") { $rr->class($zone_class); } } } if ($section eq "answer" || $section eq "pre") { push(@{$self->{"answer"}}, @rr); my $ancount = $self->{"header"}->ancount; $self->{"header"}->ancount($ancount + @rr); } elsif ($section eq "authority" || $section eq "update") { push(@{$self->{"authority"}}, @rr); my $nscount = $self->{"header"}->nscount; $self->{"header"}->nscount($nscount + @rr); } elsif ($section eq "additional") { push(@{$self->{"additional"}}, @rr); my $adcount = $self->{"header"}->adcount; $self->{"header"}->adcount($adcount + @rr); } elsif ($section eq "question") { push(@{$self->{"question"}}, @rr); my $qdcount = $self->{"header"}->qdcount; $self->{"header"}->qdcount($qdcount + @rr); } else { Carp::carp(qq(invalid section "$section"\n)); return; } } =head2 unique_push $packet->unique_push(pre => $rr); $packet->unique_push(update => $rr); $packet->unique_push(additional => $rr); $packet->unique_push(update => $rr1, $rr2, $rr3); $packet->unique_push(update => @rr); Adds RRs to the specified section of the packet provided that the RRs do not already exist in the packet. =cut sub unique_push { my ($self, $section, @rrs) = @_; foreach my $rr (@rrs) { next if $self->{'seen'}->{$rr->string}++; $self->push($section, $rr); } } =head2 safe_push A deprecated name for C<unique_push()>. =cut sub safe_push { carp('safe_push() is deprecated, use unique_push() instead,'); goto &unique_push; } =head2 pop my $rr = $packet->pop("pre"); my $rr = $packet->pop("update"); my $rr = $packet->pop("additional"); Removes RRs from the specified section of the packet. =cut sub pop { my ($self, $section) = @_; return unless $section; $section = lc $section; if (($section eq "prerequisite") || ($section eq "prereq")) { $section = "pre"; } my $rr; if ($section eq "answer" || $section eq "pre") { my $ancount = $self->{"header"}->ancount; if ($ancount) { $rr = pop @{$self->{"answer"}}; $self->{"header"}->ancount($ancount - 1); } } elsif ($section eq "authority" || $section eq "update") { my $nscount = $self->{"header"}->nscount; if ($nscount) { $rr = pop @{$self->{"authority"}}; $self->{"header"}->nscount($nscount - 1); } } elsif ($section eq "additional") { my $adcount = $self->{"header"}->adcount; if ($adcount) { $rr = pop @{$self->{"additional"}}; $self->{"header"}->adcount($adcount - 1); } } else { Carp::cluck(qq(invalid section "$section"\n)); } return $rr; } =head2 dn_comp $compname = $packet->dn_comp("foo.example.com", $offset); Returns a domain name compressed for a particular packet object, to be stored beginning at the given offset within the packet data. The name will be added to a running list of compressed domain names for future use. =cut sub dn_comp { my ($self, $name, $offset) = @_; $name = "" unless defined($name); my $compname = ""; my @names = map { s/\\\././g; $_ } split(/(?=[^\\]|^)\./, $name); while (@names) { my $dname = join(".", @names); if (exists $self->{"compnames"}->{$dname}) { my $pointer = $self->{"compnames"}->{$dname}; $compname .= pack("n", 0xc000 | $pointer); last; } $self->{"compnames"}->{$dname} = $offset; my $first = shift @names; my $length = length $first; $compname .= pack("C a*", $length, $first); $offset += $length + 1; } $compname .= pack("C", 0) unless @names; return $compname; } =head2 dn_expand use Net::DNS::Packet qw(dn_expand); ($name, $nextoffset) = dn_expand(\$data, $offset); ($name, $nextoffset) = Net::DNS::Packet::dn_expand(\$data, $offset); Expands the domain name stored at a particular location in a DNS packet. The first argument is a reference to a scalar containing the packet data. The second argument is the offset within the packet where the (possibly compressed) domain name is stored. Returns the domain name and the offset of the next location in the packet. Returns B<(undef, undef)> if the domain name couldn't be expanded. =cut # ' # This is very hot code, so we try to keep things fast. This makes for # odd style sometimes. { if ($Net::DNS::HAVE_XS) { *dn_expand = \&dn_expand_XS; } else { *dn_expand = \&dn_expand_PP; } } sub dn_expand_PP { my ($packet, $offset) = @_; # $seen from $_[2] for debugging my $name = ""; my $len; my $packetlen = length $$packet; my $int16sz = Net::DNS::INT16SZ(); # Debugging #warn "USING PURE PERL dn_expand()\n"; #if ($seen->{$offset}) { # die "dn_expand: loop: offset=$offset (seen = ", # join(",", keys %$seen), ")\n"; #} #$seen->{$offset} = 1; while (1) { return (undef, undef) if $packetlen < ($offset + 1); $len = unpack("\@$offset C", $$packet); if ($len == 0) { $offset++; last; } elsif (($len & 0xc0) == 0xc0) { return (undef, undef) if $packetlen < ($offset + $int16sz); my $ptr = unpack("\@$offset n", $$packet); $ptr &= 0x3fff; my($name2) = dn_expand_PP($packet, $ptr); # pass $seen for debugging return (undef, undef) unless defined $name2; $name .= $name2; $offset += $int16sz; last; } else { $offset++; return (undef, undef) if $packetlen < ($offset + $len); my $elem = substr($$packet, $offset, $len); $elem =~ s/\./\\./g; $name .= "$elem."; $offset += $len; } } $name =~ s/\.$//; return ($name, $offset); } =head2 sign_tsig $key_name = "tsig-key"; $key = "awwLOtRfpGE+rRKF2+DEiw=="; $update = Net::DNS::Update->new("example.com"); $update->push("update", rr_add("foo.example.com A 10.1.2.3")); $update->sign_tsig($key_name, $key); $response = $res->send($update); Signs a packet with a TSIG resource record (see RFC 2845). Uses the following defaults: algorithm = HMAC-MD5.SIG-ALG.REG.INT time_signed = current time fudge = 300 seconds If you wish to customize the TSIG record, you'll have to create it yourself and call the appropriate Net::DNS::RR::TSIG methods. The following example creates a TSIG record and sets the fudge to 60 seconds: $key_name = "tsig-key"; $key = "awwLOtRfpGE+rRKF2+DEiw=="; $tsig = Net::DNS::RR->new("$key_name TSIG $key"); $tsig->fudge(60); $query = Net::DNS::Packet->new("www.example.com"); $query->sign_tsig($tsig); $response = $res->send($query); You shouldn't modify a packet after signing it; otherwise authentication will probably fail. =cut sub sign_tsig { my $self = shift; my $tsig; if (@_ == 1 && ref($_[0])) { $tsig = $_[0]; } elsif (@_ == 2) { my ($key_name, $key) = @_; if (defined($key_name) && defined($key)) { $tsig = Net::DNS::RR->new("$key_name TSIG $key") } } $self->push("additional", $tsig) if $tsig; return $tsig; } =head2 sign_sig0 SIG0 support is provided through the Net::DNS::RR::SIG class. This class is not part of the default Net::DNS distribution but resides in the Net::DNS::SEC distribution. $update = Net::DNS::Update->new("example.com"); $update->push("update", rr_add("foo.example.com A 10.1.2.3")); $update->sign_sig0("Kexample.com+003+25317.private"); SIG0 support is experimental see Net::DNS::RR::SIG for details. The method will call C<Carp::croak()> if Net::DNS::RR::SIG cannot be found. =cut sub sign_sig0 { my $self = shift; Carp::croak('The sign_sig0() method is only available when the Net::DNS::SEC package is installed.') unless $Net::DNS::DNSSEC; my $sig0; if (@_ == 1 && ref($_[0])) { if (UNIVERSAL::isa($_[0],"Net::DNS::RR::SIG::Private")) { Carp::carp('Net::DNS::RR::SIG::Private is deprecated use Net::DNS::SEC::Private instead'); $sig0 = Net::DNS::RR::SIG->create('', $_[0]) if $_[0]; } elsif (UNIVERSAL::isa($_[0],"Net::DNS::SEC::Private")) { $sig0 = Net::DNS::RR::SIG->create('', $_[0]) if $_[0]; } elsif (UNIVERSAL::isa($_[0],"Net::DNS::RR::SIG")) { $sig0 = $_[0]; } else { Carp::croak('You are passing an incompatible class as argument to sign_sig0: ' . ref($_[0])); } } elsif (@_ == 1 && ! ref($_[0])) { my $key_name = $_[0]; $sig0 = Net::DNS::RR::SIG->create('', $key_name) if $key_name } $self->push('additional', $sig0) if $sig0; return $sig0; } #------------------------------------------------------------------------------ # parse_question # # ($queryobj, $newoffset) = parse_question(\$data, $offset); # # Parses a question section record contained at a particular location within # a DNS packet. The first argument is a reference to the packet data. The # second argument is the offset within the packet where the question record # begins. # # Returns a Net::DNS::Question object and the offset of the next location # in the packet. # # Returns (undef, undef) if the question object couldn't be created (e.g., # if there isn't enough data). #------------------------------------------------------------------------------ sub parse_question { my ($data, $offset) = @_; my $qname; ($qname, $offset) = dn_expand($data, $offset); return (undef, undef) unless defined $qname; return (undef, undef) if length($$data) < ($offset + 2 * Net::DNS::INT16SZ()); my ($qtype, $qclass) = unpack("\@$offset n2", $$data); $offset += 2 * Net::DNS::INT16SZ(); $qtype = Net::DNS::typesbyval($qtype); $qclass = Net::DNS::classesbyval($qclass); return (Net::DNS::Question->new($qname, $qtype, $qclass), $offset); } #------------------------------------------------------------------------------ # parse_rr # # ($rrobj, $newoffset) = parse_rr(\$data, $offset); # # Parses a DNS resource record (RR) contained at a particular location # within a DNS packet. The first argument is a reference to a scalar # containing the packet data. The second argument is the offset within # the data where the RR is located. # # Returns a Net::DNS::RR object and the offset of the next location # in the packet. #------------------------------------------------------------------------------ sub parse_rr { my ($data, $offset) = @_; my $name; ($name, $offset) = dn_expand($data, $offset); return (undef, undef) unless defined $name; return (undef, undef) if length($$data) < ($offset + Net::DNS::RRFIXEDSZ()); my ($type, $class, $ttl, $rdlength) = unpack("\@$offset n2 N n", $$data); $type = Net::DNS::typesbyval($type) || $type; # Special case for OPT RR where CLASS should be interperted as 16 bit # unsigned 2671 sec 4.3 if ($type ne "OPT") { $class = Net::DNS::classesbyval($class) || $class; } # else just keep at its numerical value $offset += Net::DNS::RRFIXEDSZ(); return (undef, undef) if length($$data) < ($offset + $rdlength); my $rrobj = Net::DNS::RR->new($name, $type, $class, $ttl, $rdlength, $data, $offset); return (undef, undef) unless defined $rrobj; $offset += $rdlength; return ($rrobj, $offset); } =head1 COPYRIGHT Copyright (c) 1997-2002 Michael Fuhr. Portions Copyright (c) 2002-2004 Chris Reinhardt. All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself. DNSSEC/EDNS0 functionality courtesy of Olaf M. Kolkman, RIPE NCC. =head1 SEE ALSO L<perl(1)>, L<Net::DNS>, L<Net::DNS::Resolver>, L<Net::DNS::Update>, L<Net::DNS::Header>, L<Net::DNS::Question>, L<Net::DNS::RR>, RFC 1035 Section 4.1, RFC 2136 Section 2, RFC 2845 =cut 1;
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