our %opcode_id = (
   query  => 0,
   iquery => 1,
   status => 2,
   notify => 4,
   update => 5,
   map +($_ => $_), 3, 6..15
);

our %opcode_str = reverse %opcode_id;

our %rcode_id = (
   noerror  =>  0,
   formerr  =>  1,
   servfail =>  2,
   nxdomain =>  3,
   notimp   =>  4,
   refused  =>  5,
   yxdomain =>  6, # Name Exists when it should not     [RFC 2136]
   yxrrset  =>  7, # RR Set Exists when it should not   [RFC 2136]
   nxrrset  =>  8, # RR Set that should exist does not  [RFC 2136]
   notauth  =>  9, # Server Not Authoritative for zone  [RFC 2136]
   notzone  => 10, # Name not contained in zone         [RFC 2136]
# EDNS0  16    BADVERS   Bad OPT Version                    [RFC 2671]
# EDNS0  16    BADSIG    TSIG Signature Failure             [RFC 2845]
# EDNS0  17    BADKEY    Key not recognized                 [RFC 2845]
# EDNS0  18    BADTIME   Signature out of time window       [RFC 2845]
# EDNS0  19    BADMODE   Bad TKEY Mode                      [RFC 2930]
# EDNS0  20    BADNAME   Duplicate key name                 [RFC 2930]
# EDNS0  21    BADALG    Algorithm not supported            [RFC 2930]
   map +($_ => $_), 11..15
);

our %rcode_str = reverse %rcode_id;

our %type_id = (
   a     =>   1,
   ns    =>   2,
   md    =>   3,
   mf    =>   4,
   cname =>   5,
   soa   =>   6,
   mb    =>   7,
   mg    =>   8,
   mr    =>   9,
   null  =>  10,
   wks   =>  11,
   ptr   =>  12,
   hinfo =>  13,
   minfo =>  14,
   mx    =>  15,
   txt   =>  16,
   aaaa  =>  28,
   srv   =>  33,
   naptr =>  35, # rfc2915
   opt   =>  41,
   spf   =>  99,
   tkey  => 249,
   tsig  => 250,
   ixfr  => 251,
   axfr  => 252,
   mailb => 253,
   "*"   => 255,
);

our %type_str = reverse %type_id;

our %class_id = (
   in   =>   1,
   ch   =>   3,
   hs   =>   4,
   none => 254,
   "*"  => 255,
);

our %class_str = reverse %class_id;

sub _enc_name($) {
   pack "(C/a*)*", (split /\./, shift), ""
}

sub _enc_qd() {
   (_enc_name $_->[0]) . pack "nn",
     ($_->[1] > 0 ? $_->[1] : $type_id {$_->[1]}),
     ($_->[2] > 0 ? $_->[2] : $class_id{$_->[2] || "in"})
}

sub _enc_rr() {
   die "encoding of resource records is not supported";
}

=item $pkt = AnyEvent::DNS::dns_pack $dns

Packs a perl data structure into a DNS packet. Reading RFC 1035 is strongly
recommended, then everything will be totally clear. Or maybe not.

Resource records are not yet encodable.

Examples: