mirror of
https://github.com/miekg/dns.git
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ff7d445081
* Avoid setting the Rdlength field when packing The offset of the end of the header is now returned from the RR.pack method, with the RDLENGTH record field being written in packRR. To maintain compatability with callers of PackRR who might be relying on this old behaviour, PackRR will now set rr.Header().Rdlength for external callers. Care must be taken by callers to ensure this won't cause a data-race. * Prevent panic if TestClientLocalAddress fails This came up during testing of the previous change. * Change style of overflow check in packRR
634 lines
17 KiB
Go
634 lines
17 KiB
Go
package dns
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import (
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"encoding/base32"
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"encoding/base64"
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"encoding/binary"
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"encoding/hex"
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"net"
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"strings"
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)
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// helper functions called from the generated zmsg.go
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// These function are named after the tag to help pack/unpack, if there is no tag it is the name
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// of the type they pack/unpack (string, int, etc). We prefix all with unpackData or packData, so packDataA or
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// packDataDomainName.
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func unpackDataA(msg []byte, off int) (net.IP, int, error) {
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if off+net.IPv4len > len(msg) {
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return nil, len(msg), &Error{err: "overflow unpacking a"}
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}
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a := append(make(net.IP, 0, net.IPv4len), msg[off:off+net.IPv4len]...)
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off += net.IPv4len
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return a, off, nil
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}
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func packDataA(a net.IP, msg []byte, off int) (int, error) {
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// It must be a slice of 4, even if it is 16, we encode only the first 4
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if off+net.IPv4len > len(msg) {
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return len(msg), &Error{err: "overflow packing a"}
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}
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switch len(a) {
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case net.IPv4len, net.IPv6len:
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copy(msg[off:], a.To4())
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off += net.IPv4len
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case 0:
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// Allowed, for dynamic updates.
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default:
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return len(msg), &Error{err: "overflow packing a"}
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}
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return off, nil
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}
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func unpackDataAAAA(msg []byte, off int) (net.IP, int, error) {
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if off+net.IPv6len > len(msg) {
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return nil, len(msg), &Error{err: "overflow unpacking aaaa"}
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}
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aaaa := append(make(net.IP, 0, net.IPv6len), msg[off:off+net.IPv6len]...)
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off += net.IPv6len
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return aaaa, off, nil
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}
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func packDataAAAA(aaaa net.IP, msg []byte, off int) (int, error) {
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if off+net.IPv6len > len(msg) {
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return len(msg), &Error{err: "overflow packing aaaa"}
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}
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switch len(aaaa) {
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case net.IPv6len:
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copy(msg[off:], aaaa)
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off += net.IPv6len
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case 0:
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// Allowed, dynamic updates.
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default:
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return len(msg), &Error{err: "overflow packing aaaa"}
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}
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return off, nil
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}
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// unpackHeader unpacks an RR header, returning the offset to the end of the header and a
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// re-sliced msg according to the expected length of the RR.
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func unpackHeader(msg []byte, off int) (rr RR_Header, off1 int, truncmsg []byte, err error) {
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hdr := RR_Header{}
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if off == len(msg) {
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return hdr, off, msg, nil
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}
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hdr.Name, off, err = UnpackDomainName(msg, off)
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if err != nil {
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return hdr, len(msg), msg, err
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}
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hdr.Rrtype, off, err = unpackUint16(msg, off)
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if err != nil {
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return hdr, len(msg), msg, err
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}
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hdr.Class, off, err = unpackUint16(msg, off)
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if err != nil {
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return hdr, len(msg), msg, err
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}
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hdr.Ttl, off, err = unpackUint32(msg, off)
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if err != nil {
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return hdr, len(msg), msg, err
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}
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hdr.Rdlength, off, err = unpackUint16(msg, off)
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if err != nil {
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return hdr, len(msg), msg, err
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}
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msg, err = truncateMsgFromRdlength(msg, off, hdr.Rdlength)
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return hdr, off, msg, err
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}
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// pack packs an RR header, returning the offset to the end of the header.
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// See PackDomainName for documentation about the compression.
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func (hdr RR_Header) pack(msg []byte, off int, compression compressionMap, compress bool) (int, int, error) {
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if off == len(msg) {
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return off, off, nil
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}
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off, _, err := packDomainName(hdr.Name, msg, off, compression, compress)
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if err != nil {
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return off, len(msg), err
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}
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off, err = packUint16(hdr.Rrtype, msg, off)
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if err != nil {
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return off, len(msg), err
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}
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off, err = packUint16(hdr.Class, msg, off)
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if err != nil {
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return off, len(msg), err
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}
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off, err = packUint32(hdr.Ttl, msg, off)
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if err != nil {
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return off, len(msg), err
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}
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off, err = packUint16(0, msg, off) // The RDLENGTH field will be set later in packRR.
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if err != nil {
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return off, len(msg), err
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}
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return off, off, nil
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}
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// helper helper functions.
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// truncateMsgFromRdLength truncates msg to match the expected length of the RR.
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// Returns an error if msg is smaller than the expected size.
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func truncateMsgFromRdlength(msg []byte, off int, rdlength uint16) (truncmsg []byte, err error) {
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lenrd := off + int(rdlength)
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if lenrd > len(msg) {
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return msg, &Error{err: "overflowing header size"}
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}
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return msg[:lenrd], nil
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}
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var base32HexNoPadEncoding = base32.HexEncoding.WithPadding(base32.NoPadding)
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func fromBase32(s []byte) (buf []byte, err error) {
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for i, b := range s {
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if b >= 'a' && b <= 'z' {
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s[i] = b - 32
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}
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}
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buflen := base32HexNoPadEncoding.DecodedLen(len(s))
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buf = make([]byte, buflen)
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n, err := base32HexNoPadEncoding.Decode(buf, s)
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buf = buf[:n]
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return
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}
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func toBase32(b []byte) string {
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return base32HexNoPadEncoding.EncodeToString(b)
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}
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func fromBase64(s []byte) (buf []byte, err error) {
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buflen := base64.StdEncoding.DecodedLen(len(s))
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buf = make([]byte, buflen)
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n, err := base64.StdEncoding.Decode(buf, s)
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buf = buf[:n]
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return
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}
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func toBase64(b []byte) string { return base64.StdEncoding.EncodeToString(b) }
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// dynamicUpdate returns true if the Rdlength is zero.
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func noRdata(h RR_Header) bool { return h.Rdlength == 0 }
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func unpackUint8(msg []byte, off int) (i uint8, off1 int, err error) {
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if off+1 > len(msg) {
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return 0, len(msg), &Error{err: "overflow unpacking uint8"}
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}
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return uint8(msg[off]), off + 1, nil
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}
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func packUint8(i uint8, msg []byte, off int) (off1 int, err error) {
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if off+1 > len(msg) {
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return len(msg), &Error{err: "overflow packing uint8"}
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}
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msg[off] = byte(i)
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return off + 1, nil
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}
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func unpackUint16(msg []byte, off int) (i uint16, off1 int, err error) {
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if off+2 > len(msg) {
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return 0, len(msg), &Error{err: "overflow unpacking uint16"}
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}
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return binary.BigEndian.Uint16(msg[off:]), off + 2, nil
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}
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func packUint16(i uint16, msg []byte, off int) (off1 int, err error) {
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if off+2 > len(msg) {
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return len(msg), &Error{err: "overflow packing uint16"}
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}
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binary.BigEndian.PutUint16(msg[off:], i)
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return off + 2, nil
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}
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func unpackUint32(msg []byte, off int) (i uint32, off1 int, err error) {
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if off+4 > len(msg) {
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return 0, len(msg), &Error{err: "overflow unpacking uint32"}
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}
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return binary.BigEndian.Uint32(msg[off:]), off + 4, nil
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}
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func packUint32(i uint32, msg []byte, off int) (off1 int, err error) {
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if off+4 > len(msg) {
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return len(msg), &Error{err: "overflow packing uint32"}
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}
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binary.BigEndian.PutUint32(msg[off:], i)
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return off + 4, nil
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}
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func unpackUint48(msg []byte, off int) (i uint64, off1 int, err error) {
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if off+6 > len(msg) {
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return 0, len(msg), &Error{err: "overflow unpacking uint64 as uint48"}
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}
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// Used in TSIG where the last 48 bits are occupied, so for now, assume a uint48 (6 bytes)
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i = uint64(msg[off])<<40 | uint64(msg[off+1])<<32 | uint64(msg[off+2])<<24 | uint64(msg[off+3])<<16 |
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uint64(msg[off+4])<<8 | uint64(msg[off+5])
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off += 6
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return i, off, nil
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}
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func packUint48(i uint64, msg []byte, off int) (off1 int, err error) {
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if off+6 > len(msg) {
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return len(msg), &Error{err: "overflow packing uint64 as uint48"}
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}
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msg[off] = byte(i >> 40)
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msg[off+1] = byte(i >> 32)
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msg[off+2] = byte(i >> 24)
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msg[off+3] = byte(i >> 16)
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msg[off+4] = byte(i >> 8)
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msg[off+5] = byte(i)
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off += 6
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return off, nil
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}
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func unpackUint64(msg []byte, off int) (i uint64, off1 int, err error) {
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if off+8 > len(msg) {
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return 0, len(msg), &Error{err: "overflow unpacking uint64"}
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}
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return binary.BigEndian.Uint64(msg[off:]), off + 8, nil
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}
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func packUint64(i uint64, msg []byte, off int) (off1 int, err error) {
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if off+8 > len(msg) {
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return len(msg), &Error{err: "overflow packing uint64"}
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}
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binary.BigEndian.PutUint64(msg[off:], i)
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off += 8
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return off, nil
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}
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func unpackString(msg []byte, off int) (string, int, error) {
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if off+1 > len(msg) {
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return "", off, &Error{err: "overflow unpacking txt"}
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}
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l := int(msg[off])
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if off+l+1 > len(msg) {
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return "", off, &Error{err: "overflow unpacking txt"}
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}
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var s strings.Builder
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s.Grow(l)
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for _, b := range msg[off+1 : off+1+l] {
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switch {
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case b == '"' || b == '\\':
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s.WriteByte('\\')
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s.WriteByte(b)
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case b < ' ' || b > '~': // unprintable
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s.WriteString(escapeByte(b))
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default:
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s.WriteByte(b)
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}
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}
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off += 1 + l
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return s.String(), off, nil
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}
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func packString(s string, msg []byte, off int) (int, error) {
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txtTmp := make([]byte, 256*4+1)
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off, err := packTxtString(s, msg, off, txtTmp)
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if err != nil {
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return len(msg), err
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}
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return off, nil
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}
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func unpackStringBase32(msg []byte, off, end int) (string, int, error) {
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if end > len(msg) {
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return "", len(msg), &Error{err: "overflow unpacking base32"}
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}
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s := toBase32(msg[off:end])
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return s, end, nil
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}
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func packStringBase32(s string, msg []byte, off int) (int, error) {
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b32, err := fromBase32([]byte(s))
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if err != nil {
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return len(msg), err
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}
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if off+len(b32) > len(msg) {
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return len(msg), &Error{err: "overflow packing base32"}
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}
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copy(msg[off:off+len(b32)], b32)
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off += len(b32)
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return off, nil
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}
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func unpackStringBase64(msg []byte, off, end int) (string, int, error) {
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// Rest of the RR is base64 encoded value, so we don't need an explicit length
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// to be set. Thus far all RR's that have base64 encoded fields have those as their
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// last one. What we do need is the end of the RR!
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if end > len(msg) {
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return "", len(msg), &Error{err: "overflow unpacking base64"}
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}
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s := toBase64(msg[off:end])
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return s, end, nil
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}
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func packStringBase64(s string, msg []byte, off int) (int, error) {
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b64, err := fromBase64([]byte(s))
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if err != nil {
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return len(msg), err
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}
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if off+len(b64) > len(msg) {
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return len(msg), &Error{err: "overflow packing base64"}
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}
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copy(msg[off:off+len(b64)], b64)
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off += len(b64)
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return off, nil
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}
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func unpackStringHex(msg []byte, off, end int) (string, int, error) {
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// Rest of the RR is hex encoded value, so we don't need an explicit length
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// to be set. NSEC and TSIG have hex fields with a length field.
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// What we do need is the end of the RR!
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if end > len(msg) {
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return "", len(msg), &Error{err: "overflow unpacking hex"}
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}
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s := hex.EncodeToString(msg[off:end])
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return s, end, nil
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}
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func packStringHex(s string, msg []byte, off int) (int, error) {
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h, err := hex.DecodeString(s)
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if err != nil {
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return len(msg), err
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}
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if off+len(h) > len(msg) {
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return len(msg), &Error{err: "overflow packing hex"}
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}
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copy(msg[off:off+len(h)], h)
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off += len(h)
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return off, nil
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}
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func unpackStringTxt(msg []byte, off int) ([]string, int, error) {
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txt, off, err := unpackTxt(msg, off)
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if err != nil {
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return nil, len(msg), err
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}
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return txt, off, nil
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}
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func packStringTxt(s []string, msg []byte, off int) (int, error) {
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txtTmp := make([]byte, 256*4+1) // If the whole string consists out of \DDD we need this many.
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off, err := packTxt(s, msg, off, txtTmp)
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if err != nil {
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return len(msg), err
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}
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return off, nil
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}
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func unpackDataOpt(msg []byte, off int) ([]EDNS0, int, error) {
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var edns []EDNS0
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Option:
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code := uint16(0)
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if off+4 > len(msg) {
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return nil, len(msg), &Error{err: "overflow unpacking opt"}
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}
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code = binary.BigEndian.Uint16(msg[off:])
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off += 2
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optlen := binary.BigEndian.Uint16(msg[off:])
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off += 2
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if off+int(optlen) > len(msg) {
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return nil, len(msg), &Error{err: "overflow unpacking opt"}
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}
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switch code {
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case EDNS0NSID:
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e := new(EDNS0_NSID)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0SUBNET:
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e := new(EDNS0_SUBNET)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0COOKIE:
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e := new(EDNS0_COOKIE)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0UL:
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e := new(EDNS0_UL)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0LLQ:
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e := new(EDNS0_LLQ)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0DAU:
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e := new(EDNS0_DAU)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0DHU:
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e := new(EDNS0_DHU)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0N3U:
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e := new(EDNS0_N3U)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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case EDNS0PADDING:
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e := new(EDNS0_PADDING)
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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default:
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e := new(EDNS0_LOCAL)
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e.Code = code
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if err := e.unpack(msg[off : off+int(optlen)]); err != nil {
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return nil, len(msg), err
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}
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edns = append(edns, e)
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off += int(optlen)
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}
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if off < len(msg) {
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goto Option
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}
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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
|
|
}
|