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533 lines
15 KiB
533 lines
15 KiB
package dns
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import (
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"encoding/binary"
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"encoding/hex"
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"errors"
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"net"
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"strconv"
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)
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// EDNS0 Option codes.
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const (
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EDNS0LLQ = 0x1 // long lived queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
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EDNS0UL = 0x2 // update lease draft: http://files.dns-sd.org/draft-sekar-dns-ul.txt
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EDNS0NSID = 0x3 // nsid (RFC5001)
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EDNS0DAU = 0x5 // DNSSEC Algorithm Understood
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EDNS0DHU = 0x6 // DS Hash Understood
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EDNS0N3U = 0x7 // NSEC3 Hash Understood
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EDNS0SUBNET = 0x8 // client-subnet (RFC6891)
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EDNS0EXPIRE = 0x9 // EDNS0 expire
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EDNS0COOKIE = 0xa // EDNS0 Cookie
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EDNS0SUBNETDRAFT = 0x50fa // Don't use! Use EDNS0SUBNET
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EDNS0LOCALSTART = 0xFDE9 // Beginning of range reserved for local/experimental use (RFC6891)
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EDNS0LOCALEND = 0xFFFE // End of range reserved for local/experimental use (RFC6891)
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_DO = 1 << 15 // dnssec ok
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)
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// OPT is the EDNS0 RR appended to messages to convey extra (meta) information.
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// See RFC 6891.
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type OPT struct {
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Hdr RR_Header
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Option []EDNS0 `dns:"opt"`
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}
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func (rr *OPT) String() string {
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s := "\n;; OPT PSEUDOSECTION:\n; EDNS: version " + strconv.Itoa(int(rr.Version())) + "; "
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if rr.Do() {
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s += "flags: do; "
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} else {
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s += "flags: ; "
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}
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s += "udp: " + strconv.Itoa(int(rr.UDPSize()))
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for _, o := range rr.Option {
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switch o.(type) {
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case *EDNS0_NSID:
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s += "\n; NSID: " + o.String()
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h, e := o.pack()
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var r string
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if e == nil {
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for _, c := range h {
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r += "(" + string(c) + ")"
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}
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s += " " + r
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}
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case *EDNS0_SUBNET:
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s += "\n; SUBNET: " + o.String()
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if o.(*EDNS0_SUBNET).DraftOption {
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s += " (draft)"
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}
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case *EDNS0_COOKIE:
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s += "\n; COOKIE: " + o.String()
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case *EDNS0_UL:
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s += "\n; UPDATE LEASE: " + o.String()
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case *EDNS0_LLQ:
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s += "\n; LONG LIVED QUERIES: " + o.String()
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case *EDNS0_DAU:
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s += "\n; DNSSEC ALGORITHM UNDERSTOOD: " + o.String()
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case *EDNS0_DHU:
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s += "\n; DS HASH UNDERSTOOD: " + o.String()
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case *EDNS0_N3U:
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s += "\n; NSEC3 HASH UNDERSTOOD: " + o.String()
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case *EDNS0_LOCAL:
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s += "\n; LOCAL OPT: " + o.String()
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}
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}
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return s
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}
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func (rr *OPT) len() int {
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l := rr.Hdr.len()
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for i := 0; i < len(rr.Option); i++ {
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l += 4 // Account for 2-byte option code and 2-byte option length.
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lo, _ := rr.Option[i].pack()
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l += len(lo)
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}
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return l
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}
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// return the old value -> delete SetVersion?
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// Version returns the EDNS version used. Only zero is defined.
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func (rr *OPT) Version() uint8 {
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return uint8((rr.Hdr.Ttl & 0x00FF0000) >> 16)
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}
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// SetVersion sets the version of EDNS. This is usually zero.
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func (rr *OPT) SetVersion(v uint8) {
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rr.Hdr.Ttl = rr.Hdr.Ttl&0xFF00FFFF | (uint32(v) << 16)
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}
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// ExtendedRcode returns the EDNS extended RCODE field (the upper 8 bits of the TTL).
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func (rr *OPT) ExtendedRcode() int {
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return int((rr.Hdr.Ttl&0xFF000000)>>24) + 15
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}
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// SetExtendedRcode sets the EDNS extended RCODE field.
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func (rr *OPT) SetExtendedRcode(v uint8) {
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if v < RcodeBadVers { // Smaller than 16.. Use the 4 bits you have!
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return
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}
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rr.Hdr.Ttl = rr.Hdr.Ttl&0x00FFFFFF | (uint32(v-15) << 24)
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}
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// UDPSize returns the UDP buffer size.
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func (rr *OPT) UDPSize() uint16 {
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return rr.Hdr.Class
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}
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// SetUDPSize sets the UDP buffer size.
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func (rr *OPT) SetUDPSize(size uint16) {
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rr.Hdr.Class = size
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}
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// Do returns the value of the DO (DNSSEC OK) bit.
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func (rr *OPT) Do() bool {
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return rr.Hdr.Ttl&_DO == _DO
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}
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// SetDo sets the DO (DNSSEC OK) bit.
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func (rr *OPT) SetDo() {
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rr.Hdr.Ttl |= _DO
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}
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// EDNS0 defines an EDNS0 Option. An OPT RR can have multiple options appended to it.
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type EDNS0 interface {
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// Option returns the option code for the option.
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Option() uint16
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// pack returns the bytes of the option data.
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pack() ([]byte, error)
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// unpack sets the data as found in the buffer. Is also sets
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// the length of the slice as the length of the option data.
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unpack([]byte) error
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// String returns the string representation of the option.
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String() string
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}
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// The nsid EDNS0 option is used to retrieve a nameserver
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// identifier. When sending a request Nsid must be set to the empty string
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// The identifier is an opaque string encoded as hex.
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// Basic use pattern for creating an nsid option:
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//
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// o := new(dns.OPT)
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// o.Hdr.Name = "."
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// o.Hdr.Rrtype = dns.TypeOPT
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// e := new(dns.EDNS0_NSID)
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// e.Code = dns.EDNS0NSID
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// e.Nsid = "AA"
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// o.Option = append(o.Option, e)
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type EDNS0_NSID struct {
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Code uint16 // Always EDNS0NSID
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Nsid string // This string needs to be hex encoded
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}
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func (e *EDNS0_NSID) pack() ([]byte, error) {
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h, err := hex.DecodeString(e.Nsid)
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if err != nil {
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return nil, err
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}
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return h, nil
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}
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func (e *EDNS0_NSID) Option() uint16 { return EDNS0NSID }
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func (e *EDNS0_NSID) unpack(b []byte) error { e.Nsid = hex.EncodeToString(b); return nil }
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func (e *EDNS0_NSID) String() string { return string(e.Nsid) }
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// EDNS0_SUBNET is the subnet option that is used to give the remote nameserver
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// an idea of where the client lives. It can then give back a different
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// answer depending on the location or network topology.
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// Basic use pattern for creating an subnet option:
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//
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// o := new(dns.OPT)
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// o.Hdr.Name = "."
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// o.Hdr.Rrtype = dns.TypeOPT
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// e := new(dns.EDNS0_SUBNET)
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// e.Code = dns.EDNS0SUBNET
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// e.Family = 1 // 1 for IPv4 source address, 2 for IPv6
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// e.NetMask = 32 // 32 for IPV4, 128 for IPv6
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// e.SourceScope = 0
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// e.Address = net.ParseIP("127.0.0.1").To4() // for IPv4
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// // e.Address = net.ParseIP("2001:7b8:32a::2") // for IPV6
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// o.Option = append(o.Option, e)
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//
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// Note: the spec (draft-ietf-dnsop-edns-client-subnet-00) has some insane logic
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// for which netmask applies to the address. This code will parse all the
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// available bits when unpacking (up to optlen). When packing it will apply
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// SourceNetmask. If you need more advanced logic, patches welcome and good luck.
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type EDNS0_SUBNET struct {
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Code uint16 // Always EDNS0SUBNET
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Family uint16 // 1 for IP, 2 for IP6
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SourceNetmask uint8
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SourceScope uint8
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Address net.IP
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DraftOption bool // Set to true if using the old (0x50fa) option code
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}
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func (e *EDNS0_SUBNET) Option() uint16 {
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if e.DraftOption {
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return EDNS0SUBNETDRAFT
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}
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return EDNS0SUBNET
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}
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func (e *EDNS0_SUBNET) pack() ([]byte, error) {
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b := make([]byte, 4)
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binary.BigEndian.PutUint16(b[0:], e.Family)
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b[2] = e.SourceNetmask
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b[3] = e.SourceScope
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switch e.Family {
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case 1:
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if e.SourceNetmask > net.IPv4len*8 {
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return nil, errors.New("dns: bad netmask")
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}
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if len(e.Address.To4()) != net.IPv4len {
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return nil, errors.New("dns: bad address")
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}
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ip := e.Address.To4().Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv4len*8))
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needLength := (e.SourceNetmask + 8 - 1) / 8 // division rounding up
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b = append(b, ip[:needLength]...)
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case 2:
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if e.SourceNetmask > net.IPv6len*8 {
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return nil, errors.New("dns: bad netmask")
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}
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if len(e.Address) != net.IPv6len {
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return nil, errors.New("dns: bad address")
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}
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ip := e.Address.Mask(net.CIDRMask(int(e.SourceNetmask), net.IPv6len*8))
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needLength := (e.SourceNetmask + 8 - 1) / 8 // division rounding up
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b = append(b, ip[:needLength]...)
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default:
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return nil, errors.New("dns: bad address family")
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}
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return b, nil
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}
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func (e *EDNS0_SUBNET) unpack(b []byte) error {
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if len(b) < 4 {
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return ErrBuf
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}
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e.Family = binary.BigEndian.Uint16(b)
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e.SourceNetmask = b[2]
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e.SourceScope = b[3]
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switch e.Family {
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case 1:
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if e.SourceNetmask > net.IPv4len*8 || e.SourceScope > net.IPv4len*8 {
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return errors.New("dns: bad netmask")
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}
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addr := make([]byte, net.IPv4len)
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for i := 0; i < net.IPv4len && 4+i < len(b); i++ {
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addr[i] = b[4+i]
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}
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e.Address = net.IPv4(addr[0], addr[1], addr[2], addr[3])
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case 2:
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if e.SourceNetmask > net.IPv6len*8 || e.SourceScope > net.IPv6len*8 {
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return errors.New("dns: bad netmask")
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}
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addr := make([]byte, net.IPv6len)
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for i := 0; i < net.IPv6len && 4+i < len(b); i++ {
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addr[i] = b[4+i]
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}
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e.Address = net.IP{addr[0], addr[1], addr[2], addr[3], addr[4],
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addr[5], addr[6], addr[7], addr[8], addr[9], addr[10],
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addr[11], addr[12], addr[13], addr[14], addr[15]}
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default:
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return errors.New("dns: bad address family")
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}
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return nil
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}
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func (e *EDNS0_SUBNET) String() (s string) {
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if e.Address == nil {
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s = "<nil>"
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} else if e.Address.To4() != nil {
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s = e.Address.String()
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} else {
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s = "[" + e.Address.String() + "]"
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}
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s += "/" + strconv.Itoa(int(e.SourceNetmask)) + "/" + strconv.Itoa(int(e.SourceScope))
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return
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}
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// The Cookie EDNS0 option
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//
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// o := new(dns.OPT)
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// o.Hdr.Name = "."
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// o.Hdr.Rrtype = dns.TypeOPT
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// e := new(dns.EDNS0_COOKIE)
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// e.Code = dns.EDNS0COOKIE
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// e.Cookie = "24a5ac.."
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// o.Option = append(o.Option, e)
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//
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// The Cookie field consists out of a client cookie (RFC 7873 Section 4), that is
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// always 8 bytes. It may then optionally be followed by the server cookie. The server
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// cookie is of variable length, 8 to a maximum of 32 bytes. In other words:
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//
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// cCookie := o.Cookie[:16]
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// sCookie := o.Cookie[16:]
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//
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// There is no guarantee that the Cookie string has a specific length.
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type EDNS0_COOKIE struct {
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Code uint16 // Always EDNS0COOKIE
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Cookie string // Hex-encoded cookie data
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}
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func (e *EDNS0_COOKIE) pack() ([]byte, error) {
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h, err := hex.DecodeString(e.Cookie)
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if err != nil {
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return nil, err
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}
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return h, nil
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}
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func (e *EDNS0_COOKIE) Option() uint16 { return EDNS0COOKIE }
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func (e *EDNS0_COOKIE) unpack(b []byte) error { e.Cookie = hex.EncodeToString(b); return nil }
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func (e *EDNS0_COOKIE) String() string { return e.Cookie }
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// The EDNS0_UL (Update Lease) (draft RFC) option is used to tell the server to set
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// an expiration on an update RR. This is helpful for clients that cannot clean
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// up after themselves. This is a draft RFC and more information can be found at
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// http://files.dns-sd.org/draft-sekar-dns-ul.txt
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//
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// o := new(dns.OPT)
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// o.Hdr.Name = "."
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// o.Hdr.Rrtype = dns.TypeOPT
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// e := new(dns.EDNS0_UL)
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// e.Code = dns.EDNS0UL
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// e.Lease = 120 // in seconds
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// o.Option = append(o.Option, e)
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type EDNS0_UL struct {
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Code uint16 // Always EDNS0UL
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Lease uint32
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}
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func (e *EDNS0_UL) Option() uint16 { return EDNS0UL }
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func (e *EDNS0_UL) String() string { return strconv.FormatUint(uint64(e.Lease), 10) }
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// Copied: http://golang.org/src/pkg/net/dnsmsg.go
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func (e *EDNS0_UL) pack() ([]byte, error) {
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b := make([]byte, 4)
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binary.BigEndian.PutUint32(b, e.Lease)
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return b, nil
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}
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func (e *EDNS0_UL) unpack(b []byte) error {
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if len(b) < 4 {
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return ErrBuf
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}
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e.Lease = binary.BigEndian.Uint32(b)
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return nil
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}
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// EDNS0_LLQ stands for Long Lived Queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
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// Implemented for completeness, as the EDNS0 type code is assigned.
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type EDNS0_LLQ struct {
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Code uint16 // Always EDNS0LLQ
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Version uint16
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Opcode uint16
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Error uint16
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Id uint64
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LeaseLife uint32
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}
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func (e *EDNS0_LLQ) Option() uint16 { return EDNS0LLQ }
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func (e *EDNS0_LLQ) pack() ([]byte, error) {
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b := make([]byte, 18)
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binary.BigEndian.PutUint16(b[0:], e.Version)
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binary.BigEndian.PutUint16(b[2:], e.Opcode)
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binary.BigEndian.PutUint16(b[4:], e.Error)
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binary.BigEndian.PutUint64(b[6:], e.Id)
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binary.BigEndian.PutUint32(b[14:], e.LeaseLife)
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return b, nil
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}
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func (e *EDNS0_LLQ) unpack(b []byte) error {
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if len(b) < 18 {
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return ErrBuf
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}
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e.Version = binary.BigEndian.Uint16(b[0:])
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e.Opcode = binary.BigEndian.Uint16(b[2:])
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e.Error = binary.BigEndian.Uint16(b[4:])
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e.Id = binary.BigEndian.Uint64(b[6:])
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e.LeaseLife = binary.BigEndian.Uint32(b[14:])
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return nil
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}
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func (e *EDNS0_LLQ) String() string {
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s := strconv.FormatUint(uint64(e.Version), 10) + " " + strconv.FormatUint(uint64(e.Opcode), 10) +
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" " + strconv.FormatUint(uint64(e.Error), 10) + " " + strconv.FormatUint(uint64(e.Id), 10) +
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" " + strconv.FormatUint(uint64(e.LeaseLife), 10)
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return s
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}
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type EDNS0_DAU struct {
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Code uint16 // Always EDNS0DAU
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AlgCode []uint8
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}
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func (e *EDNS0_DAU) Option() uint16 { return EDNS0DAU }
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func (e *EDNS0_DAU) pack() ([]byte, error) { return e.AlgCode, nil }
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func (e *EDNS0_DAU) unpack(b []byte) error { e.AlgCode = b; return nil }
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func (e *EDNS0_DAU) String() string {
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s := ""
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for i := 0; i < len(e.AlgCode); i++ {
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if a, ok := AlgorithmToString[e.AlgCode[i]]; ok {
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s += " " + a
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} else {
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s += " " + strconv.Itoa(int(e.AlgCode[i]))
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}
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}
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return s
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}
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type EDNS0_DHU struct {
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Code uint16 // Always EDNS0DHU
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AlgCode []uint8
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}
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func (e *EDNS0_DHU) Option() uint16 { return EDNS0DHU }
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func (e *EDNS0_DHU) pack() ([]byte, error) { return e.AlgCode, nil }
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func (e *EDNS0_DHU) unpack(b []byte) error { e.AlgCode = b; return nil }
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func (e *EDNS0_DHU) String() string {
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s := ""
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for i := 0; i < len(e.AlgCode); i++ {
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if a, ok := HashToString[e.AlgCode[i]]; ok {
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s += " " + a
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} else {
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s += " " + strconv.Itoa(int(e.AlgCode[i]))
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}
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}
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return s
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}
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type EDNS0_N3U struct {
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Code uint16 // Always EDNS0N3U
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AlgCode []uint8
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}
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func (e *EDNS0_N3U) Option() uint16 { return EDNS0N3U }
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func (e *EDNS0_N3U) pack() ([]byte, error) { return e.AlgCode, nil }
|
|
func (e *EDNS0_N3U) unpack(b []byte) error { e.AlgCode = b; return nil }
|
|
|
|
func (e *EDNS0_N3U) String() string {
|
|
// Re-use the hash map
|
|
s := ""
|
|
for i := 0; i < len(e.AlgCode); i++ {
|
|
if a, ok := HashToString[e.AlgCode[i]]; ok {
|
|
s += " " + a
|
|
} else {
|
|
s += " " + strconv.Itoa(int(e.AlgCode[i]))
|
|
}
|
|
}
|
|
return s
|
|
}
|
|
|
|
type EDNS0_EXPIRE struct {
|
|
Code uint16 // Always EDNS0EXPIRE
|
|
Expire uint32
|
|
}
|
|
|
|
func (e *EDNS0_EXPIRE) Option() uint16 { return EDNS0EXPIRE }
|
|
func (e *EDNS0_EXPIRE) String() string { return strconv.FormatUint(uint64(e.Expire), 10) }
|
|
|
|
func (e *EDNS0_EXPIRE) pack() ([]byte, error) {
|
|
b := make([]byte, 4)
|
|
b[0] = byte(e.Expire >> 24)
|
|
b[1] = byte(e.Expire >> 16)
|
|
b[2] = byte(e.Expire >> 8)
|
|
b[3] = byte(e.Expire)
|
|
return b, nil
|
|
}
|
|
|
|
func (e *EDNS0_EXPIRE) unpack(b []byte) error {
|
|
if len(b) < 4 {
|
|
return ErrBuf
|
|
}
|
|
e.Expire = binary.BigEndian.Uint32(b)
|
|
return nil
|
|
}
|
|
|
|
// The EDNS0_LOCAL option is used for local/experimental purposes. The option
|
|
// code is recommended to be within the range [EDNS0LOCALSTART, EDNS0LOCALEND]
|
|
// (RFC6891), although any unassigned code can actually be used. The content of
|
|
// the option is made available in Data, unaltered.
|
|
// Basic use pattern for creating a local option:
|
|
//
|
|
// o := new(dns.OPT)
|
|
// o.Hdr.Name = "."
|
|
// o.Hdr.Rrtype = dns.TypeOPT
|
|
// e := new(dns.EDNS0_LOCAL)
|
|
// e.Code = dns.EDNS0LOCALSTART
|
|
// e.Data = []byte{72, 82, 74}
|
|
// o.Option = append(o.Option, e)
|
|
type EDNS0_LOCAL struct {
|
|
Code uint16
|
|
Data []byte
|
|
}
|
|
|
|
func (e *EDNS0_LOCAL) Option() uint16 { return e.Code }
|
|
func (e *EDNS0_LOCAL) String() string {
|
|
return strconv.FormatInt(int64(e.Code), 10) + ":0x" + hex.EncodeToString(e.Data)
|
|
}
|
|
|
|
func (e *EDNS0_LOCAL) pack() ([]byte, error) {
|
|
b := make([]byte, len(e.Data))
|
|
copied := copy(b, e.Data)
|
|
if copied != len(e.Data) {
|
|
return nil, ErrBuf
|
|
}
|
|
return b, nil
|
|
}
|
|
|
|
func (e *EDNS0_LOCAL) unpack(b []byte) error {
|
|
e.Data = make([]byte, len(b))
|
|
copied := copy(e.Data, b)
|
|
if copied != len(b) {
|
|
return ErrBuf
|
|
}
|
|
return nil
|
|
}
|