--- /dev/null
+package dns
+
+import (
+ "encoding/base32"
+ "encoding/base64"
+ "encoding/binary"
+ "encoding/hex"
+ "net"
+ "bytes"
+)
+
+// helper functions called from the generated zmsg.go
+
+// These function are named after the tag to help pack/unpack, if there is no tag it is the name
+// of the type they pack/unpack (string, int, etc). We prefix all with unpackData or packData, so packDataA or
+// packDataDomainName.
+
+func unpackDataA(msg []byte, off int) (net.IP, int, error) {
+ if off+net.IPv4len > len(msg) {
+ return nil, len(msg), &Error{err: "overflow unpacking a"}
+ }
+ a := append(make(net.IP, 0, net.IPv4len), msg[off:off+net.IPv4len]...)
+ off += net.IPv4len
+ return a, off, nil
+}
+
+func packDataA(a net.IP, msg []byte, off int) (int, error) {
+ // It must be a slice of 4, even if it is 16, we encode only the first 4
+ if off+net.IPv4len > len(msg) {
+ return len(msg), &Error{err: "overflow packing a"}
+ }
+ switch len(a) {
+ case net.IPv4len, net.IPv6len:
+ copy(msg[off:], a.To4())
+ off += net.IPv4len
+ case 0:
+ // Allowed, for dynamic updates.
+ default:
+ return len(msg), &Error{err: "overflow packing a"}
+ }
+ return off, nil
+}
+
+func unpackDataAAAA(msg []byte, off int) (net.IP, int, error) {
+ if off+net.IPv6len > len(msg) {
+ return nil, len(msg), &Error{err: "overflow unpacking aaaa"}
+ }
+ aaaa := append(make(net.IP, 0, net.IPv6len), msg[off:off+net.IPv6len]...)
+ off += net.IPv6len
+ return aaaa, off, nil
+}
+
+func packDataAAAA(aaaa net.IP, msg []byte, off int) (int, error) {
+ if off+net.IPv6len > len(msg) {
+ return len(msg), &Error{err: "overflow packing aaaa"}
+ }
+
+ switch len(aaaa) {
+ case net.IPv6len:
+ copy(msg[off:], aaaa)
+ off += net.IPv6len
+ case 0:
+ // Allowed, dynamic updates.
+ default:
+ return len(msg), &Error{err: "overflow packing aaaa"}
+ }
+ return off, nil
+}
+
+// unpackHeader unpacks an RR header, returning the offset to the end of the header and a
+// re-sliced msg according to the expected length of the RR.
+func unpackHeader(msg []byte, off int) (rr RR_Header, off1 int, truncmsg []byte, err error) {
+ hdr := RR_Header{}
+ if off == len(msg) {
+ return hdr, off, msg, nil
+ }
+
+ hdr.Name, off, err = UnpackDomainName(msg, off)
+ if err != nil {
+ return hdr, len(msg), msg, err
+ }
+ hdr.Rrtype, off, err = unpackUint16(msg, off)
+ if err != nil {
+ return hdr, len(msg), msg, err
+ }
+ hdr.Class, off, err = unpackUint16(msg, off)
+ if err != nil {
+ return hdr, len(msg), msg, err
+ }
+ hdr.Ttl, off, err = unpackUint32(msg, off)
+ if err != nil {
+ return hdr, len(msg), msg, err
+ }
+ hdr.Rdlength, off, err = unpackUint16(msg, off)
+ if err != nil {
+ return hdr, len(msg), msg, err
+ }
+ msg, err = truncateMsgFromRdlength(msg, off, hdr.Rdlength)
+ return hdr, off, msg, err
+}
+
+// packHeader packs an RR header, returning the offset to the end of the header.
+// See PackDomainName for documentation about the compression.
+func (hdr RR_Header) packHeader(msg []byte, off int, compression compressionMap, compress bool) (int, error) {
+ if off == len(msg) {
+ return off, nil
+ }
+
+ off, err := packDomainName(hdr.Name, msg, off, compression, compress)
+ if err != nil {
+ return len(msg), err
+ }
+ off, err = packUint16(hdr.Rrtype, msg, off)
+ if err != nil {
+ return len(msg), err
+ }
+ off, err = packUint16(hdr.Class, msg, off)
+ if err != nil {
+ return len(msg), err
+ }
+ off, err = packUint32(hdr.Ttl, msg, off)
+ if err != nil {
+ return len(msg), err
+ }
+ off, err = packUint16(0, msg, off) // The RDLENGTH field will be set later in packRR.
+ if err != nil {
+ return len(msg), err
+ }
+ return off, nil
+}
+
+// helper helper functions.
+
+// truncateMsgFromRdLength truncates msg to match the expected length of the RR.
+// Returns an error if msg is smaller than the expected size.
+func truncateMsgFromRdlength(msg []byte, off int, rdlength uint16) (truncmsg []byte, err error) {
+ lenrd := off + int(rdlength)
+ if lenrd > len(msg) {
+ return msg, &Error{err: "overflowing header size"}
+ }
+ return msg[:lenrd], nil
+}
+
+var base32HexNoPadEncoding = base32.HexEncoding
+
+func fromBase32(s []byte) (buf []byte, err error) {
+ for i, b := range s {
+ if b >= 'a' && b <= 'z' {
+ s[i] = b - 32
+ }
+ }
+ buflen := base32HexNoPadEncoding.DecodedLen(len(s))
+ buf = make([]byte, buflen)
+ n, err := base32HexNoPadEncoding.Decode(buf, s)
+ buf = buf[:n]
+ return
+}
+
+func toBase32(b []byte) string {
+ return base32HexNoPadEncoding.EncodeToString(b)
+}
+
+func fromBase64(s []byte) (buf []byte, err error) {
+ buflen := base64.StdEncoding.DecodedLen(len(s))
+ buf = make([]byte, buflen)
+ n, err := base64.StdEncoding.Decode(buf, s)
+ buf = buf[:n]
+ return
+}
+
+func toBase64(b []byte) string { return base64.StdEncoding.EncodeToString(b) }
+
+// dynamicUpdate returns true if the Rdlength is zero.
+func noRdata(h RR_Header) bool { return h.Rdlength == 0 }
+
+func unpackUint8(msg []byte, off int) (i uint8, off1 int, err error) {
+ if off+1 > len(msg) {
+ return 0, len(msg), &Error{err: "overflow unpacking uint8"}
+ }
+ return msg[off], off + 1, nil
+}
+
+func packUint8(i uint8, msg []byte, off int) (off1 int, err error) {
+ if off+1 > len(msg) {
+ return len(msg), &Error{err: "overflow packing uint8"}
+ }
+ msg[off] = i
+ return off + 1, nil
+}
+
+func unpackUint16(msg []byte, off int) (i uint16, off1 int, err error) {
+ if off+2 > len(msg) {
+ return 0, len(msg), &Error{err: "overflow unpacking uint16"}
+ }
+ return binary.BigEndian.Uint16(msg[off:]), off + 2, nil
+}
+
+func packUint16(i uint16, msg []byte, off int) (off1 int, err error) {
+ if off+2 > len(msg) {
+ return len(msg), &Error{err: "overflow packing uint16"}
+ }
+ binary.BigEndian.PutUint16(msg[off:], i)
+ return off + 2, nil
+}
+
+func unpackUint32(msg []byte, off int) (i uint32, off1 int, err error) {
+ if off+4 > len(msg) {
+ return 0, len(msg), &Error{err: "overflow unpacking uint32"}
+ }
+ return binary.BigEndian.Uint32(msg[off:]), off + 4, nil
+}
+
+func packUint32(i uint32, msg []byte, off int) (off1 int, err error) {
+ if off+4 > len(msg) {
+ return len(msg), &Error{err: "overflow packing uint32"}
+ }
+ binary.BigEndian.PutUint32(msg[off:], i)
+ return off + 4, nil
+}
+
+func unpackUint48(msg []byte, off int) (i uint64, off1 int, err error) {
+ if off+6 > len(msg) {
+ return 0, len(msg), &Error{err: "overflow unpacking uint64 as uint48"}
+ }
+ // Used in TSIG where the last 48 bits are occupied, so for now, assume a uint48 (6 bytes)
+ i = uint64(msg[off])<<40 | uint64(msg[off+1])<<32 | uint64(msg[off+2])<<24 | uint64(msg[off+3])<<16 |
+ uint64(msg[off+4])<<8 | uint64(msg[off+5])
+ off += 6
+ return i, off, nil
+}
+
+func packUint48(i uint64, msg []byte, off int) (off1 int, err error) {
+ if off+6 > len(msg) {
+ return len(msg), &Error{err: "overflow packing uint64 as uint48"}
+ }
+ msg[off] = byte(i >> 40)
+ msg[off+1] = byte(i >> 32)
+ msg[off+2] = byte(i >> 24)
+ msg[off+3] = byte(i >> 16)
+ msg[off+4] = byte(i >> 8)
+ msg[off+5] = byte(i)
+ off += 6
+ return off, nil
+}
+
+func unpackUint64(msg []byte, off int) (i uint64, off1 int, err error) {
+ if off+8 > len(msg) {
+ return 0, len(msg), &Error{err: "overflow unpacking uint64"}
+ }
+ return binary.BigEndian.Uint64(msg[off:]), off + 8, nil
+}
+
+func packUint64(i uint64, msg []byte, off int) (off1 int, err error) {
+ if off+8 > len(msg) {
+ return len(msg), &Error{err: "overflow packing uint64"}
+ }
+ binary.BigEndian.PutUint64(msg[off:], i)
+ off += 8
+ return off, nil
+}
+
+func unpackString(msg []byte, off int) (string, int, error) {
+ if off+1 > len(msg) {
+ return "", off, &Error{err: "overflow unpacking txt"}
+ }
+ l := int(msg[off])
+ if off+l+1 > len(msg) {
+ return "", off, &Error{err: "overflow unpacking txt"}
+ }
+ var s bytes.Buffer
+ s.Grow(l)
+ for _, b := range msg[off+1 : off+1+l] {
+ switch {
+ case b == '"' || b == '\\':
+ s.WriteByte('\\')
+ s.WriteByte(b)
+ case b < ' ' || b > '~': // unprintable
+ s.WriteString(escapeByte(b))
+ default:
+ s.WriteByte(b)
+ }
+ }
+ off += 1 + l
+ return s.String(), off, nil
+}
+
+func packString(s string, msg []byte, off int) (int, error) {
+ txtTmp := make([]byte, 256*4+1)
+ off, err := packTxtString(s, msg, off, txtTmp)
+ if err != nil {
+ return len(msg), err
+ }
+ return off, nil
+}
+
+func unpackStringBase32(msg []byte, off, end int) (string, int, error) {
+ if end > len(msg) {
+ return "", len(msg), &Error{err: "overflow unpacking base32"}
+ }
+ s := toBase32(msg[off:end])
+ return s, end, nil
+}
+
+func packStringBase32(s string, msg []byte, off int) (int, error) {
+ b32, err := fromBase32([]byte(s))
+ if err != nil {
+ return len(msg), err
+ }
+ if off+len(b32) > len(msg) {
+ return len(msg), &Error{err: "overflow packing base32"}
+ }
+ copy(msg[off:off+len(b32)], b32)
+ off += len(b32)
+ return off, nil
+}
+
+func unpackStringBase64(msg []byte, off, end int) (string, int, error) {
+ // Rest of the RR is base64 encoded value, so we don't need an explicit length
+ // to be set. Thus far all RR's that have base64 encoded fields have those as their
+ // last one. What we do need is the end of the RR!
+ if end > len(msg) {
+ return "", len(msg), &Error{err: "overflow unpacking base64"}
+ }
+ s := toBase64(msg[off:end])
+ return s, end, nil
+}
+
+func packStringBase64(s string, msg []byte, off int) (int, error) {
+ b64, err := fromBase64([]byte(s))
+ if err != nil {
+ return len(msg), err
+ }
+ if off+len(b64) > len(msg) {
+ return len(msg), &Error{err: "overflow packing base64"}
+ }
+ copy(msg[off:off+len(b64)], b64)
+ off += len(b64)
+ return off, nil
+}
+
+func unpackStringHex(msg []byte, off, end int) (string, int, error) {
+ // Rest of the RR is hex encoded value, so we don't need an explicit length
+ // to be set. NSEC and TSIG have hex fields with a length field.
+ // What we do need is the end of the RR!
+ if end > len(msg) {
+ return "", len(msg), &Error{err: "overflow unpacking hex"}
+ }
+
+ s := hex.EncodeToString(msg[off:end])
+ return s, end, nil
+}
+
+func packStringHex(s string, msg []byte, off int) (int, error) {
+ h, err := hex.DecodeString(s)
+ if err != nil {
+ return len(msg), err
+ }
+ if off+len(h) > len(msg) {
+ return len(msg), &Error{err: "overflow packing hex"}
+ }
+ copy(msg[off:off+len(h)], h)
+ off += len(h)
+ return off, nil
+}
+
+func unpackStringAny(msg []byte, off, end int) (string, int, error) {
+ if end > len(msg) {
+ return "", len(msg), &Error{err: "overflow unpacking anything"}
+ }
+ return string(msg[off:end]), end, nil
+}
+
+func packStringAny(s string, msg []byte, off int) (int, error) {
+ if off+len(s) > len(msg) {
+ return len(msg), &Error{err: "overflow packing anything"}
+ }
+ copy(msg[off:off+len(s)], s)
+ off += len(s)
+ return off, nil
+}
+
+func unpackStringTxt(msg []byte, off int) ([]string, int, error) {
+ txt, off, err := unpackTxt(msg, off)
+ if err != nil {
+ return nil, len(msg), err
+ }
+ return txt, off, nil
+}
+
+func packStringTxt(s []string, msg []byte, off int) (int, error) {
+ txtTmp := make([]byte, 256*4+1) // If the whole string consists out of \DDD we need this many.
+ off, err := packTxt(s, msg, off, txtTmp)
+ if err != nil {
+ return len(msg), err
+ }
+ return off, nil
+}
+
+func unpackDataOpt(msg []byte, off int) ([]EDNS0, int, error) {
+ var edns []EDNS0
+Option:
+ var code uint16
+ if off+4 > len(msg) {
+ return nil, len(msg), &Error{err: "overflow unpacking opt"}
+ }
+ code = binary.BigEndian.Uint16(msg[off:])
+ off += 2
+ optlen := binary.BigEndian.Uint16(msg[off:])
+ off += 2
+ if off+int(optlen) > len(msg) {
+ return nil, len(msg), &Error{err: "overflow unpacking opt"}
+ }
+ switch code {
+ case EDNS0NSID:
+ e := new(EDNS0_NSID)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0SUBNET:
+ e := new(EDNS0_SUBNET)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0COOKIE:
+ e := new(EDNS0_COOKIE)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0UL:
+ e := new(EDNS0_UL)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0LLQ:
+ e := new(EDNS0_LLQ)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0DAU:
+ e := new(EDNS0_DAU)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0DHU:
+ e := new(EDNS0_DHU)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0N3U:
+ e := new(EDNS0_N3U)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ case EDNS0PADDING:
+ e := new(EDNS0_PADDING)
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ default:
+ e := new(EDNS0_LOCAL)
+ e.Code = code
+ if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
+ return nil, len(msg), err
+ }
+ edns = append(edns, e)
+ off += int(optlen)
+ }
+
+ if off < len(msg) {
+ goto Option
+ }
+
+ return edns, off, nil
+}
+
+func packDataOpt(options []EDNS0, msg []byte, off int) (int, error) {
+ for _, el := range options {
+ b, err := el.pack()
+ if err != nil || off+3 > len(msg) {
+ return len(msg), &Error{err: "overflow packing opt"}
+ }
+ binary.BigEndian.PutUint16(msg[off:], el.Option()) // Option code
+ binary.BigEndian.PutUint16(msg[off+2:], uint16(len(b))) // Length
+ off += 4
+ if off+len(b) > len(msg) {
+ copy(msg[off:], b)
+ off = len(msg)
+ continue
+ }
+ // Actual data
+ copy(msg[off:off+len(b)], b)
+ off += len(b)
+ }
+ return off, nil
+}
+
+func unpackStringOctet(msg []byte, off int) (string, int, error) {
+ s := string(msg[off:])
+ return s, len(msg), nil
+}
+
+func packStringOctet(s string, msg []byte, off int) (int, error) {
+ txtTmp := make([]byte, 256*4+1)
+ off, err := packOctetString(s, msg, off, txtTmp)
+ if err != nil {
+ return len(msg), err
+ }
+ return off, nil
+}
+
+func unpackDataNsec(msg []byte, off int) ([]uint16, int, error) {
+ var nsec []uint16
+ length, window, lastwindow := 0, 0, -1
+ for off < len(msg) {
+ if off+2 > len(msg) {
+ return nsec, len(msg), &Error{err: "overflow unpacking nsecx"}
+ }
+ window = int(msg[off])
+ length = int(msg[off+1])
+ off += 2
+ if window <= lastwindow {
+ // RFC 4034: Blocks are present in the NSEC RR RDATA in
+ // increasing numerical order.
+ return nsec, len(msg), &Error{err: "out of order NSEC block"}
+ }
+ if length == 0 {
+ // RFC 4034: Blocks with no types present MUST NOT be included.
+ return nsec, len(msg), &Error{err: "empty NSEC block"}
+ }
+ if length > 32 {
+ return nsec, len(msg), &Error{err: "NSEC block too long"}
+ }
+ if off+length > len(msg) {
+ return nsec, len(msg), &Error{err: "overflowing NSEC block"}
+ }
+
+ // Walk the bytes in the window and extract the type bits
+ for j := 0; j < length; j++ {
+ b := msg[off+j]
+ // Check the bits one by one, and set the type
+ if b&0x80 == 0x80 {
+ nsec = append(nsec, uint16(window*256+j*8+0))
+ }
+ if b&0x40 == 0x40 {
+ nsec = append(nsec, uint16(window*256+j*8+1))
+ }
+ if b&0x20 == 0x20 {
+ nsec = append(nsec, uint16(window*256+j*8+2))
+ }
+ if b&0x10 == 0x10 {
+ nsec = append(nsec, uint16(window*256+j*8+3))
+ }
+ if b&0x8 == 0x8 {
+ nsec = append(nsec, uint16(window*256+j*8+4))
+ }
+ if b&0x4 == 0x4 {
+ nsec = append(nsec, uint16(window*256+j*8+5))
+ }
+ if b&0x2 == 0x2 {
+ nsec = append(nsec, uint16(window*256+j*8+6))
+ }
+ if b&0x1 == 0x1 {
+ nsec = append(nsec, uint16(window*256+j*8+7))
+ }
+ }
+ off += length
+ lastwindow = window
+ }
+ return nsec, off, nil
+}
+
+func packDataNsec(bitmap []uint16, msg []byte, off int) (int, error) {
+ if len(bitmap) == 0 {
+ return off, nil
+ }
+ var lastwindow, lastlength uint16
+ for j := 0; j < len(bitmap); j++ {
+ t := bitmap[j]
+ window := t / 256
+ length := (t-window*256)/8 + 1
+ if window > lastwindow && lastlength != 0 { // New window, jump to the new offset
+ off += int(lastlength) + 2
+ lastlength = 0
+ }
+ if window < lastwindow || length < lastlength {
+ return len(msg), &Error{err: "nsec bits out of order"}
+ }
+ if off+2+int(length) > len(msg) {
+ return len(msg), &Error{err: "overflow packing nsec"}
+ }
+ // Setting the window #
+ msg[off] = byte(window)
+ // Setting the octets length
+ msg[off+1] = byte(length)
+ // Setting the bit value for the type in the right octet
+ msg[off+1+int(length)] |= byte(1 << (7 - t%8))
+ lastwindow, lastlength = window, length
+ }
+ off += int(lastlength) + 2
+ return off, nil
+}
+
+func unpackDataDomainNames(msg []byte, off, end int) ([]string, int, error) {
+ var (
+ servers []string
+ s string
+ err error
+ )
+ if end > len(msg) {
+ return nil, len(msg), &Error{err: "overflow unpacking domain names"}
+ }
+ for off < end {
+ s, off, err = UnpackDomainName(msg, off)
+ if err != nil {
+ return servers, len(msg), err
+ }
+ servers = append(servers, s)
+ }
+ return servers, off, nil
+}
+
+func packDataDomainNames(names []string, msg []byte, off int, compression compressionMap, compress bool) (int, error) {
+ var err error
+ for j := 0; j < len(names); j++ {
+ off, err = packDomainName(names[j], msg, off, compression, compress)
+ if err != nil {
+ return len(msg), err
+ }
+ }
+ return off, nil
+}
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