[chore] Validate/set account domain (#619)

* add miekg/dns dependency

* set/validate accountDomain

1 files changed, 812 insertions, 0 deletions

diff --git a/vendor/github.com/miekg/dns/msg_helpers.go b/vendor/github.com/miekg/dns/msg_helpers.go
new file mode 100644
index 000000000..b049028b7
--- /dev/null
+++ b/vendor/github.com/miekg/dns/msg_helpers.go
@@ -0,0 +1,812 @@
+package dns
+
+import (
+	"encoding/base32"
+	"encoding/base64"
+	"encoding/binary"
+	"encoding/hex"
+	"net"
+	"sort"
+	"strings"
+)
+
+// 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) {
+	switch len(a) {
+	case net.IPv4len, net.IPv6len:
+		// 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"}
+		}
+
+		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) {
+	switch len(aaaa) {
+	case net.IPv6len:
+		if off+net.IPv6len > len(msg) {
+			return len(msg), &Error{err: "overflow packing aaaa"}
+		}
+
+		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.WithPadding(base32.NoPadding)
+
+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])
+	off++
+	if off+l > len(msg) {
+		return "", off, &Error{err: "overflow unpacking txt"}
+	}
+	var s strings.Builder
+	consumed := 0
+	for i, b := range msg[off : off+l] {
+		switch {
+		case b == '"' || b == '\\':
+			if consumed == 0 {
+				s.Grow(l * 2)
+			}
+			s.Write(msg[off+consumed : off+i])
+			s.WriteByte('\\')
+			s.WriteByte(b)
+			consumed = i + 1
+		case b < ' ' || b > '~': // unprintable
+			if consumed == 0 {
+				s.Grow(l * 2)
+			}
+			s.Write(msg[off+consumed : off+i])
+			s.WriteString(escapeByte(b))
+			consumed = i + 1
+		}
+	}
+	if consumed == 0 { // no escaping needed
+		return string(msg[off : off+l]), off + l, nil
+	}
+	s.Write(msg[off+consumed : off+l])
+	return s.String(), off + l, 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"}
+	}
+	e := makeDataOpt(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+4 > 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) {
+			return len(msg), &Error{err: "overflow packing opt"}
+		}
+		// 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, b := range msg[off : off+length] {
+			// 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
+}
+
+// typeBitMapLen is a helper function which computes the "maximum" length of
+// a the NSEC Type BitMap field.
+func typeBitMapLen(bitmap []uint16) int {
+	var l int
+	var lastwindow, lastlength uint16
+	for _, t := range bitmap {
+		window := t / 256
+		length := (t-window*256)/8 + 1
+		if window > lastwindow && lastlength != 0 { // New window, jump to the new offset
+			l += int(lastlength) + 2
+			lastlength = 0
+		}
+		if window < lastwindow || length < lastlength {
+			// packDataNsec would return Error{err: "nsec bits out of order"} here, but
+			// when computing the length, we want do be liberal.
+			continue
+		}
+		lastwindow, lastlength = window, length
+	}
+	l += int(lastlength) + 2
+	return l
+}
+
+func packDataNsec(bitmap []uint16, msg []byte, off int) (int, error) {
+	if len(bitmap) == 0 {
+		return off, nil
+	}
+	if off > len(msg) {
+		return off, &Error{err: "overflow packing nsec"}
+	}
+	toZero := msg[off:]
+	if maxLen := typeBitMapLen(bitmap); maxLen < len(toZero) {
+		toZero = toZero[:maxLen]
+	}
+	for i := range toZero {
+		toZero[i] = 0
+	}
+	var lastwindow, lastlength uint16
+	for _, t := range bitmap {
+		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 unpackDataSVCB(msg []byte, off int) ([]SVCBKeyValue, int, error) {
+	var xs []SVCBKeyValue
+	var code uint16
+	var length uint16
+	var err error
+	for off < len(msg) {
+		code, off, err = unpackUint16(msg, off)
+		if err != nil {
+			return nil, len(msg), &Error{err: "overflow unpacking SVCB"}
+		}
+		length, off, err = unpackUint16(msg, off)
+		if err != nil || off+int(length) > len(msg) {
+			return nil, len(msg), &Error{err: "overflow unpacking SVCB"}
+		}
+		e := makeSVCBKeyValue(SVCBKey(code))
+		if e == nil {
+			return nil, len(msg), &Error{err: "bad SVCB key"}
+		}
+		if err := e.unpack(msg[off : off+int(length)]); err != nil {
+			return nil, len(msg), err
+		}
+		if len(xs) > 0 && e.Key() <= xs[len(xs)-1].Key() {
+			return nil, len(msg), &Error{err: "SVCB keys not in strictly increasing order"}
+		}
+		xs = append(xs, e)
+		off += int(length)
+	}
+	return xs, off, nil
+}
+
+func packDataSVCB(pairs []SVCBKeyValue, msg []byte, off int) (int, error) {
+	pairs = append([]SVCBKeyValue(nil), pairs...)
+	sort.Slice(pairs, func(i, j int) bool {
+		return pairs[i].Key() < pairs[j].Key()
+	})
+	prev := svcb_RESERVED
+	for _, el := range pairs {
+		if el.Key() == prev {
+			return len(msg), &Error{err: "repeated SVCB keys are not allowed"}
+		}
+		prev = el.Key()
+		packed, err := el.pack()
+		if err != nil {
+			return len(msg), err
+		}
+		off, err = packUint16(uint16(el.Key()), msg, off)
+		if err != nil {
+			return len(msg), &Error{err: "overflow packing SVCB"}
+		}
+		off, err = packUint16(uint16(len(packed)), msg, off)
+		if err != nil || off+len(packed) > len(msg) {
+			return len(msg), &Error{err: "overflow packing SVCB"}
+		}
+		copy(msg[off:off+len(packed)], packed)
+		off += len(packed)
+	}
+	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 _, name := range names {
+		off, err = packDomainName(name, msg, off, compression, compress)
+		if err != nil {
+			return len(msg), err
+		}
+	}
+	return off, nil
+}
+
+func packDataApl(data []APLPrefix, msg []byte, off int) (int, error) {
+	var err error
+	for i := range data {
+		off, err = packDataAplPrefix(&data[i], msg, off)
+		if err != nil {
+			return len(msg), err
+		}
+	}
+	return off, nil
+}
+
+func packDataAplPrefix(p *APLPrefix, msg []byte, off int) (int, error) {
+	if len(p.Network.IP) != len(p.Network.Mask) {
+		return len(msg), &Error{err: "address and mask lengths don't match"}
+	}
+
+	var err error
+	prefix, _ := p.Network.Mask.Size()
+	addr := p.Network.IP.Mask(p.Network.Mask)[:(prefix+7)/8]
+
+	switch len(p.Network.IP) {
+	case net.IPv4len:
+		off, err = packUint16(1, msg, off)
+	case net.IPv6len:
+		off, err = packUint16(2, msg, off)
+	default:
+		err = &Error{err: "unrecognized address family"}
+	}
+	if err != nil {
+		return len(msg), err
+	}
+
+	off, err = packUint8(uint8(prefix), msg, off)
+	if err != nil {
+		return len(msg), err
+	}
+
+	var n uint8
+	if p.Negation {
+		n = 0x80
+	}
+
+	// trim trailing zero bytes as specified in RFC3123 Sections 4.1 and 4.2.
+	i := len(addr) - 1
+	for ; i >= 0 && addr[i] == 0; i-- {
+	}
+	addr = addr[:i+1]
+
+	adflen := uint8(len(addr)) & 0x7f
+	off, err = packUint8(n|adflen, msg, off)
+	if err != nil {
+		return len(msg), err
+	}
+
+	if off+len(addr) > len(msg) {
+		return len(msg), &Error{err: "overflow packing APL prefix"}
+	}
+	off += copy(msg[off:], addr)
+
+	return off, nil
+}
+
+func unpackDataApl(msg []byte, off int) ([]APLPrefix, int, error) {
+	var result []APLPrefix
+	for off < len(msg) {
+		prefix, end, err := unpackDataAplPrefix(msg, off)
+		if err != nil {
+			return nil, len(msg), err
+		}
+		off = end
+		result = append(result, prefix)
+	}
+	return result, off, nil
+}
+
+func unpackDataAplPrefix(msg []byte, off int) (APLPrefix, int, error) {
+	family, off, err := unpackUint16(msg, off)
+	if err != nil {
+		return APLPrefix{}, len(msg), &Error{err: "overflow unpacking APL prefix"}
+	}
+	prefix, off, err := unpackUint8(msg, off)
+	if err != nil {
+		return APLPrefix{}, len(msg), &Error{err: "overflow unpacking APL prefix"}
+	}
+	nlen, off, err := unpackUint8(msg, off)
+	if err != nil {
+		return APLPrefix{}, len(msg), &Error{err: "overflow unpacking APL prefix"}
+	}
+
+	var ip []byte
+	switch family {
+	case 1:
+		ip = make([]byte, net.IPv4len)
+	case 2:
+		ip = make([]byte, net.IPv6len)
+	default:
+		return APLPrefix{}, len(msg), &Error{err: "unrecognized APL address family"}
+	}
+	if int(prefix) > 8*len(ip) {
+		return APLPrefix{}, len(msg), &Error{err: "APL prefix too long"}
+	}
+	afdlen := int(nlen & 0x7f)
+	if afdlen > len(ip) {
+		return APLPrefix{}, len(msg), &Error{err: "APL length too long"}
+	}
+	if off+afdlen > len(msg) {
+		return APLPrefix{}, len(msg), &Error{err: "overflow unpacking APL address"}
+	}
+
+	// Address MUST NOT contain trailing zero bytes per RFC3123 Sections 4.1 and 4.2.
+	off += copy(ip, msg[off:off+afdlen])
+	if afdlen > 0 {
+		last := ip[afdlen-1]
+		if last == 0 {
+			return APLPrefix{}, len(msg), &Error{err: "extra APL address bits"}
+		}
+	}
+	ipnet := net.IPNet{
+		IP:   ip,
+		Mask: net.CIDRMask(int(prefix), 8*len(ip)),
+	}
+
+	return APLPrefix{
+		Negation: (nlen & 0x80) != 0,
+		Network:  ipnet,
+	}, off, nil
+}