mirror of
https://github.com/moby/moby.git
synced 2022-11-09 12:21:53 -05:00
1945 lines
52 KiB
Go
1945 lines
52 KiB
Go
// DNS packet assembly, see RFC 1035. Converting from - Unpack() -
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// and to - Pack() - wire format.
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// All the packers and unpackers take a (msg []byte, off int)
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// and return (off1 int, ok bool). If they return ok==false, they
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// also return off1==len(msg), so that the next unpacker will
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// also fail. This lets us avoid checks of ok until the end of a
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// packing sequence.
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package dns
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import (
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"encoding/base32"
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"encoding/base64"
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"encoding/hex"
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"math/big"
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"math/rand"
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"net"
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"reflect"
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"strconv"
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"time"
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)
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const maxCompressionOffset = 2 << 13 // We have 14 bits for the compression pointer
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var (
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// ErrAlg indicates an error with the (DNSSEC) algorithm.
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ErrAlg error = &Error{err: "bad algorithm"}
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// ErrAuth indicates an error in the TSIG authentication.
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ErrAuth error = &Error{err: "bad authentication"}
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// ErrBuf indicates that the buffer used it too small for the message.
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ErrBuf error = &Error{err: "buffer size too small"}
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// ErrConnEmpty indicates a connection is being uses before it is initialized.
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ErrConnEmpty error = &Error{err: "conn has no connection"}
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// ErrExtendedRcode ...
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ErrExtendedRcode error = &Error{err: "bad extended rcode"}
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// ErrFqdn indicates that a domain name does not have a closing dot.
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ErrFqdn error = &Error{err: "domain must be fully qualified"}
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// ErrId indicates there is a mismatch with the message's ID.
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ErrId error = &Error{err: "id mismatch"}
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// ErrKeyAlg indicates that the algorithm in the key is not valid.
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ErrKeyAlg error = &Error{err: "bad key algorithm"}
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ErrKey error = &Error{err: "bad key"}
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ErrKeySize error = &Error{err: "bad key size"}
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ErrNoSig error = &Error{err: "no signature found"}
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ErrPrivKey error = &Error{err: "bad private key"}
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ErrRcode error = &Error{err: "bad rcode"}
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ErrRdata error = &Error{err: "bad rdata"}
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ErrRRset error = &Error{err: "bad rrset"}
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ErrSecret error = &Error{err: "no secrets defined"}
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ErrShortRead error = &Error{err: "short read"}
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// ErrSig indicates that a signature can not be cryptographically validated.
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ErrSig error = &Error{err: "bad signature"}
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// ErrSOA indicates that no SOA RR was seen when doing zone transfers.
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ErrSoa error = &Error{err: "no SOA"}
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// ErrTime indicates a timing error in TSIG authentication.
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ErrTime error = &Error{err: "bad time"}
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// ErrTruncated indicates that we failed to unpack a truncated message.
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// We unpacked as much as we had so Msg can still be used, if desired.
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ErrTruncated error = &Error{err: "failed to unpack truncated message"}
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)
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// Id, by default, returns a 16 bits random number to be used as a
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// message id. The random provided should be good enough. This being a
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// variable the function can be reassigned to a custom function.
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// For instance, to make it return a static value:
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//
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// dns.Id = func() uint16 { return 3 }
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var Id func() uint16 = id
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// MsgHdr is a a manually-unpacked version of (id, bits).
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type MsgHdr struct {
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Id uint16
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Response bool
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Opcode int
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Authoritative bool
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Truncated bool
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RecursionDesired bool
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RecursionAvailable bool
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Zero bool
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AuthenticatedData bool
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CheckingDisabled bool
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Rcode int
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}
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// Msg contains the layout of a DNS message.
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type Msg struct {
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MsgHdr
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Compress bool `json:"-"` // If true, the message will be compressed when converted to wire format. This not part of the official DNS packet format.
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Question []Question // Holds the RR(s) of the question section.
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Answer []RR // Holds the RR(s) of the answer section.
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Ns []RR // Holds the RR(s) of the authority section.
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Extra []RR // Holds the RR(s) of the additional section.
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}
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// StringToType is the reverse of TypeToString, needed for string parsing.
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var StringToType = reverseInt16(TypeToString)
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// StringToClass is the reverse of ClassToString, needed for string parsing.
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var StringToClass = reverseInt16(ClassToString)
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// Map of opcodes strings.
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var StringToOpcode = reverseInt(OpcodeToString)
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// Map of rcodes strings.
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var StringToRcode = reverseInt(RcodeToString)
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// ClassToString is a maps Classes to strings for each CLASS wire type.
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var ClassToString = map[uint16]string{
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ClassINET: "IN",
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ClassCSNET: "CS",
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ClassCHAOS: "CH",
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ClassHESIOD: "HS",
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ClassNONE: "NONE",
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ClassANY: "ANY",
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}
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// OpcodeToString maps Opcodes to strings.
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var OpcodeToString = map[int]string{
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OpcodeQuery: "QUERY",
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OpcodeIQuery: "IQUERY",
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OpcodeStatus: "STATUS",
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OpcodeNotify: "NOTIFY",
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OpcodeUpdate: "UPDATE",
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}
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// RcodeToString maps Rcodes to strings.
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var RcodeToString = map[int]string{
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RcodeSuccess: "NOERROR",
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RcodeFormatError: "FORMERR",
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RcodeServerFailure: "SERVFAIL",
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RcodeNameError: "NXDOMAIN",
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RcodeNotImplemented: "NOTIMPL",
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RcodeRefused: "REFUSED",
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RcodeYXDomain: "YXDOMAIN", // From RFC 2136
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RcodeYXRrset: "YXRRSET",
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RcodeNXRrset: "NXRRSET",
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RcodeNotAuth: "NOTAUTH",
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RcodeNotZone: "NOTZONE",
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RcodeBadSig: "BADSIG", // Also known as RcodeBadVers, see RFC 6891
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// RcodeBadVers: "BADVERS",
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RcodeBadKey: "BADKEY",
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RcodeBadTime: "BADTIME",
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RcodeBadMode: "BADMODE",
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RcodeBadName: "BADNAME",
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RcodeBadAlg: "BADALG",
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RcodeBadTrunc: "BADTRUNC",
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}
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// Rather than write the usual handful of routines to pack and
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// unpack every message that can appear on the wire, we use
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// reflection to write a generic pack/unpack for structs and then
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// use it. Thus, if in the future we need to define new message
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// structs, no new pack/unpack/printing code needs to be written.
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// Domain names are a sequence of counted strings
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// split at the dots. They end with a zero-length string.
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// PackDomainName packs a domain name s into msg[off:].
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// If compression is wanted compress must be true and the compression
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// map needs to hold a mapping between domain names and offsets
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// pointing into msg.
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func PackDomainName(s string, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error) {
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off1, _, err = packDomainName(s, msg, off, compression, compress)
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return
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}
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func packDomainName(s string, msg []byte, off int, compression map[string]int, compress bool) (off1 int, labels int, err error) {
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// special case if msg == nil
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lenmsg := 256
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if msg != nil {
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lenmsg = len(msg)
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}
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ls := len(s)
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if ls == 0 { // Ok, for instance when dealing with update RR without any rdata.
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return off, 0, nil
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}
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// If not fully qualified, error out, but only if msg == nil #ugly
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switch {
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case msg == nil:
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if s[ls-1] != '.' {
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s += "."
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ls++
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}
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case msg != nil:
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if s[ls-1] != '.' {
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return lenmsg, 0, ErrFqdn
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}
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}
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// Each dot ends a segment of the name.
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// We trade each dot byte for a length byte.
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// Except for escaped dots (\.), which are normal dots.
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// There is also a trailing zero.
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// Compression
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nameoffset := -1
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pointer := -1
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// Emit sequence of counted strings, chopping at dots.
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begin := 0
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bs := []byte(s)
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roBs, bsFresh, escapedDot := s, true, false
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for i := 0; i < ls; i++ {
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if bs[i] == '\\' {
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for j := i; j < ls-1; j++ {
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bs[j] = bs[j+1]
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}
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ls--
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if off+1 > lenmsg {
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return lenmsg, labels, ErrBuf
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}
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// check for \DDD
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if i+2 < ls && isDigit(bs[i]) && isDigit(bs[i+1]) && isDigit(bs[i+2]) {
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bs[i] = dddToByte(bs[i:])
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for j := i + 1; j < ls-2; j++ {
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bs[j] = bs[j+2]
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}
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ls -= 2
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} else if bs[i] == 't' {
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bs[i] = '\t'
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} else if bs[i] == 'r' {
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bs[i] = '\r'
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} else if bs[i] == 'n' {
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bs[i] = '\n'
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}
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escapedDot = bs[i] == '.'
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bsFresh = false
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continue
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}
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if bs[i] == '.' {
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if i > 0 && bs[i-1] == '.' && !escapedDot {
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// two dots back to back is not legal
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return lenmsg, labels, ErrRdata
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}
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if i-begin >= 1<<6 { // top two bits of length must be clear
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return lenmsg, labels, ErrRdata
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}
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// off can already (we're in a loop) be bigger than len(msg)
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// this happens when a name isn't fully qualified
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if off+1 > lenmsg {
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return lenmsg, labels, ErrBuf
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}
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if msg != nil {
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msg[off] = byte(i - begin)
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}
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offset := off
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off++
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for j := begin; j < i; j++ {
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if off+1 > lenmsg {
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return lenmsg, labels, ErrBuf
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}
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if msg != nil {
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msg[off] = bs[j]
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}
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off++
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}
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if compress && !bsFresh {
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roBs = string(bs)
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bsFresh = true
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}
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// Dont try to compress '.'
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if compress && roBs[begin:] != "." {
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if p, ok := compression[roBs[begin:]]; !ok {
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// Only offsets smaller than this can be used.
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if offset < maxCompressionOffset {
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compression[roBs[begin:]] = offset
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}
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} else {
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// The first hit is the longest matching dname
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// keep the pointer offset we get back and store
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// the offset of the current name, because that's
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// where we need to insert the pointer later
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// If compress is true, we're allowed to compress this dname
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if pointer == -1 && compress {
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pointer = p // Where to point to
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nameoffset = offset // Where to point from
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break
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}
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}
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}
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labels++
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begin = i + 1
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}
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escapedDot = false
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}
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// Root label is special
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if len(bs) == 1 && bs[0] == '.' {
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return off, labels, nil
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}
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// If we did compression and we find something add the pointer here
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if pointer != -1 {
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// We have two bytes (14 bits) to put the pointer in
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// if msg == nil, we will never do compression
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msg[nameoffset], msg[nameoffset+1] = packUint16(uint16(pointer ^ 0xC000))
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off = nameoffset + 1
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goto End
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}
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if msg != nil {
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msg[off] = 0
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}
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End:
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off++
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return off, labels, nil
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}
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// Unpack a domain name.
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// In addition to the simple sequences of counted strings above,
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// domain names are allowed to refer to strings elsewhere in the
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// packet, to avoid repeating common suffixes when returning
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// many entries in a single domain. The pointers are marked
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// by a length byte with the top two bits set. Ignoring those
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// two bits, that byte and the next give a 14 bit offset from msg[0]
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// where we should pick up the trail.
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// Note that if we jump elsewhere in the packet,
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// we return off1 == the offset after the first pointer we found,
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// which is where the next record will start.
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// In theory, the pointers are only allowed to jump backward.
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// We let them jump anywhere and stop jumping after a while.
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// UnpackDomainName unpacks a domain name into a string.
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func UnpackDomainName(msg []byte, off int) (string, int, error) {
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s := make([]byte, 0, 64)
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off1 := 0
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lenmsg := len(msg)
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ptr := 0 // number of pointers followed
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Loop:
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for {
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if off >= lenmsg {
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return "", lenmsg, ErrBuf
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}
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c := int(msg[off])
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off++
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switch c & 0xC0 {
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case 0x00:
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if c == 0x00 {
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// end of name
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break Loop
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}
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// literal string
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if off+c > lenmsg {
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return "", lenmsg, ErrBuf
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}
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for j := off; j < off+c; j++ {
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switch b := msg[j]; b {
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case '.', '(', ')', ';', ' ', '@':
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fallthrough
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case '"', '\\':
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s = append(s, '\\', b)
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case '\t':
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s = append(s, '\\', 't')
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case '\r':
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s = append(s, '\\', 'r')
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default:
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if b < 32 || b >= 127 { // unprintable use \DDD
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var buf [3]byte
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bufs := strconv.AppendInt(buf[:0], int64(b), 10)
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s = append(s, '\\')
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for i := 0; i < 3-len(bufs); i++ {
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s = append(s, '0')
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}
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for _, r := range bufs {
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s = append(s, r)
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}
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} else {
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s = append(s, b)
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}
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}
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}
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s = append(s, '.')
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off += c
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case 0xC0:
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// pointer to somewhere else in msg.
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// remember location after first ptr,
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// since that's how many bytes we consumed.
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// also, don't follow too many pointers --
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// maybe there's a loop.
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if off >= lenmsg {
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return "", lenmsg, ErrBuf
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}
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c1 := msg[off]
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off++
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if ptr == 0 {
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off1 = off
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}
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if ptr++; ptr > 10 {
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return "", lenmsg, &Error{err: "too many compression pointers"}
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}
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off = (c^0xC0)<<8 | int(c1)
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default:
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// 0x80 and 0x40 are reserved
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return "", lenmsg, ErrRdata
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}
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}
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if ptr == 0 {
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off1 = off
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}
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if len(s) == 0 {
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s = []byte(".")
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}
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return string(s), off1, nil
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}
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func packTxt(txt []string, msg []byte, offset int, tmp []byte) (int, error) {
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var err error
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if len(txt) == 0 {
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if offset >= len(msg) {
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return offset, ErrBuf
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}
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msg[offset] = 0
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return offset, nil
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}
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for i := range txt {
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if len(txt[i]) > len(tmp) {
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return offset, ErrBuf
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}
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offset, err = packTxtString(txt[i], msg, offset, tmp)
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if err != nil {
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return offset, err
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}
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}
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return offset, err
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}
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func packTxtString(s string, msg []byte, offset int, tmp []byte) (int, error) {
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lenByteOffset := offset
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if offset >= len(msg) {
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return offset, ErrBuf
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}
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offset++
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bs := tmp[:len(s)]
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copy(bs, s)
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for i := 0; i < len(bs); i++ {
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if len(msg) <= offset {
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return offset, ErrBuf
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}
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if bs[i] == '\\' {
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i++
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if i == len(bs) {
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break
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}
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// check for \DDD
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if i+2 < len(bs) && isDigit(bs[i]) && isDigit(bs[i+1]) && isDigit(bs[i+2]) {
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msg[offset] = dddToByte(bs[i:])
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i += 2
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} else if bs[i] == 't' {
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msg[offset] = '\t'
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} else if bs[i] == 'r' {
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msg[offset] = '\r'
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} else if bs[i] == 'n' {
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msg[offset] = '\n'
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} else {
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msg[offset] = bs[i]
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}
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} else {
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msg[offset] = bs[i]
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}
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offset++
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}
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l := offset - lenByteOffset - 1
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if l > 255 {
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return offset, &Error{err: "string exceeded 255 bytes in txt"}
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}
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msg[lenByteOffset] = byte(l)
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return offset, nil
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}
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func packOctetString(s string, msg []byte, offset int, tmp []byte) (int, error) {
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if offset >= len(msg) {
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return offset, ErrBuf
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}
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bs := tmp[:len(s)]
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copy(bs, s)
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for i := 0; i < len(bs); i++ {
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if len(msg) <= offset {
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return offset, ErrBuf
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}
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if bs[i] == '\\' {
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i++
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if i == len(bs) {
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break
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}
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// check for \DDD
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if i+2 < len(bs) && isDigit(bs[i]) && isDigit(bs[i+1]) && isDigit(bs[i+2]) {
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msg[offset] = dddToByte(bs[i:])
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i += 2
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} else {
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msg[offset] = bs[i]
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}
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} else {
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msg[offset] = bs[i]
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}
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offset++
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}
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return offset, nil
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}
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func unpackTxt(msg []byte, off0 int) (ss []string, off int, err error) {
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off = off0
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var s string
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for off < len(msg) && err == nil {
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s, off, err = unpackTxtString(msg, off)
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if err == nil {
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ss = append(ss, s)
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}
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}
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return
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}
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func unpackTxtString(msg []byte, offset int) (string, int, error) {
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if offset+1 > len(msg) {
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return "", offset, &Error{err: "overflow unpacking txt"}
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}
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l := int(msg[offset])
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if offset+l+1 > len(msg) {
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|
return "", offset, &Error{err: "overflow unpacking txt"}
|
|
}
|
|
s := make([]byte, 0, l)
|
|
for _, b := range msg[offset+1 : offset+1+l] {
|
|
switch b {
|
|
case '"', '\\':
|
|
s = append(s, '\\', b)
|
|
case '\t':
|
|
s = append(s, `\t`...)
|
|
case '\r':
|
|
s = append(s, `\r`...)
|
|
case '\n':
|
|
s = append(s, `\n`...)
|
|
default:
|
|
if b < 32 || b > 127 { // unprintable
|
|
var buf [3]byte
|
|
bufs := strconv.AppendInt(buf[:0], int64(b), 10)
|
|
s = append(s, '\\')
|
|
for i := 0; i < 3-len(bufs); i++ {
|
|
s = append(s, '0')
|
|
}
|
|
for _, r := range bufs {
|
|
s = append(s, r)
|
|
}
|
|
} else {
|
|
s = append(s, b)
|
|
}
|
|
}
|
|
}
|
|
offset += 1 + l
|
|
return string(s), offset, nil
|
|
}
|
|
|
|
// Pack a reflect.StructValue into msg. Struct members can only be uint8, uint16, uint32, string,
|
|
// slices and other (often anonymous) structs.
|
|
func packStructValue(val reflect.Value, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error) {
|
|
var txtTmp []byte
|
|
lenmsg := len(msg)
|
|
numfield := val.NumField()
|
|
for i := 0; i < numfield; i++ {
|
|
typefield := val.Type().Field(i)
|
|
if typefield.Tag == `dns:"-"` {
|
|
continue
|
|
}
|
|
switch fv := val.Field(i); fv.Kind() {
|
|
default:
|
|
return lenmsg, &Error{err: "bad kind packing"}
|
|
case reflect.Interface:
|
|
// PrivateRR is the only RR implementation that has interface field.
|
|
// therefore it's expected that this interface would be PrivateRdata
|
|
switch data := fv.Interface().(type) {
|
|
case PrivateRdata:
|
|
n, err := data.Pack(msg[off:])
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
off += n
|
|
default:
|
|
return lenmsg, &Error{err: "bad kind interface packing"}
|
|
}
|
|
case reflect.Slice:
|
|
switch typefield.Tag {
|
|
default:
|
|
return lenmsg, &Error{"bad tag packing slice: " + typefield.Tag.Get("dns")}
|
|
case `dns:"domain-name"`:
|
|
for j := 0; j < val.Field(i).Len(); j++ {
|
|
element := val.Field(i).Index(j).String()
|
|
off, err = PackDomainName(element, msg, off, compression, false && compress)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
}
|
|
case `dns:"txt"`:
|
|
if txtTmp == nil {
|
|
txtTmp = make([]byte, 256*4+1)
|
|
}
|
|
off, err = packTxt(fv.Interface().([]string), msg, off, txtTmp)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case `dns:"opt"`: // edns
|
|
for j := 0; j < val.Field(i).Len(); j++ {
|
|
element := val.Field(i).Index(j).Interface()
|
|
b, e := element.(EDNS0).pack()
|
|
if e != nil {
|
|
return lenmsg, &Error{err: "overflow packing opt"}
|
|
}
|
|
// Option code
|
|
msg[off], msg[off+1] = packUint16(element.(EDNS0).Option())
|
|
// Length
|
|
msg[off+2], msg[off+3] = packUint16(uint16(len(b)))
|
|
off += 4
|
|
if off+len(b) > lenmsg {
|
|
copy(msg[off:], b)
|
|
off = lenmsg
|
|
continue
|
|
}
|
|
// Actual data
|
|
copy(msg[off:off+len(b)], b)
|
|
off += len(b)
|
|
}
|
|
case `dns:"a"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, must be 1
|
|
if val.Field(2).Uint() != 1 {
|
|
continue
|
|
}
|
|
}
|
|
// It must be a slice of 4, even if it is 16, we encode
|
|
// only the first 4
|
|
if off+net.IPv4len > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing a"}
|
|
}
|
|
switch fv.Len() {
|
|
case net.IPv6len:
|
|
msg[off] = byte(fv.Index(12).Uint())
|
|
msg[off+1] = byte(fv.Index(13).Uint())
|
|
msg[off+2] = byte(fv.Index(14).Uint())
|
|
msg[off+3] = byte(fv.Index(15).Uint())
|
|
off += net.IPv4len
|
|
case net.IPv4len:
|
|
msg[off] = byte(fv.Index(0).Uint())
|
|
msg[off+1] = byte(fv.Index(1).Uint())
|
|
msg[off+2] = byte(fv.Index(2).Uint())
|
|
msg[off+3] = byte(fv.Index(3).Uint())
|
|
off += net.IPv4len
|
|
case 0:
|
|
// Allowed, for dynamic updates
|
|
default:
|
|
return lenmsg, &Error{err: "overflow packing a"}
|
|
}
|
|
case `dns:"aaaa"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, must be 2
|
|
if val.Field(2).Uint() != 2 {
|
|
continue
|
|
}
|
|
}
|
|
if fv.Len() == 0 {
|
|
break
|
|
}
|
|
if fv.Len() > net.IPv6len || off+fv.Len() > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing aaaa"}
|
|
}
|
|
for j := 0; j < net.IPv6len; j++ {
|
|
msg[off] = byte(fv.Index(j).Uint())
|
|
off++
|
|
}
|
|
case `dns:"wks"`:
|
|
// TODO(miek): this is wrong should be lenrd
|
|
if off == lenmsg {
|
|
break // dyn. updates
|
|
}
|
|
if val.Field(i).Len() == 0 {
|
|
break
|
|
}
|
|
off1 := off
|
|
for j := 0; j < val.Field(i).Len(); j++ {
|
|
serv := int(fv.Index(j).Uint())
|
|
if off+serv/8+1 > len(msg) {
|
|
return len(msg), &Error{err: "overflow packing wks"}
|
|
}
|
|
msg[off+serv/8] |= byte(1 << (7 - uint(serv%8)))
|
|
if off+serv/8+1 > off1 {
|
|
off1 = off + serv/8 + 1
|
|
}
|
|
}
|
|
off = off1
|
|
case `dns:"nsec"`: // NSEC/NSEC3
|
|
// This is the uint16 type bitmap
|
|
if val.Field(i).Len() == 0 {
|
|
// Do absolutely nothing
|
|
break
|
|
}
|
|
var lastwindow, lastlength uint16
|
|
for j := 0; j < val.Field(i).Len(); j++ {
|
|
t := uint16(fv.Index(j).Uint())
|
|
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
|
|
}
|
|
case reflect.Struct:
|
|
off, err = packStructValue(fv, msg, off, compression, compress)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case reflect.Uint8:
|
|
if off+1 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing uint8"}
|
|
}
|
|
msg[off] = byte(fv.Uint())
|
|
off++
|
|
case reflect.Uint16:
|
|
if off+2 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing uint16"}
|
|
}
|
|
i := fv.Uint()
|
|
msg[off] = byte(i >> 8)
|
|
msg[off+1] = byte(i)
|
|
off += 2
|
|
case reflect.Uint32:
|
|
if off+4 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing uint32"}
|
|
}
|
|
i := fv.Uint()
|
|
msg[off] = byte(i >> 24)
|
|
msg[off+1] = byte(i >> 16)
|
|
msg[off+2] = byte(i >> 8)
|
|
msg[off+3] = byte(i)
|
|
off += 4
|
|
case reflect.Uint64:
|
|
switch typefield.Tag {
|
|
default:
|
|
if off+8 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing uint64"}
|
|
}
|
|
i := fv.Uint()
|
|
msg[off] = byte(i >> 56)
|
|
msg[off+1] = byte(i >> 48)
|
|
msg[off+2] = byte(i >> 40)
|
|
msg[off+3] = byte(i >> 32)
|
|
msg[off+4] = byte(i >> 24)
|
|
msg[off+5] = byte(i >> 16)
|
|
msg[off+6] = byte(i >> 8)
|
|
msg[off+7] = byte(i)
|
|
off += 8
|
|
case `dns:"uint48"`:
|
|
// Used in TSIG, where it stops at 48 bits, so we discard the upper 16
|
|
if off+6 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing uint64 as uint48"}
|
|
}
|
|
i := fv.Uint()
|
|
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
|
|
}
|
|
case reflect.String:
|
|
// There are multiple string encodings.
|
|
// The tag distinguishes ordinary strings from domain names.
|
|
s := fv.String()
|
|
switch typefield.Tag {
|
|
default:
|
|
return lenmsg, &Error{"bad tag packing string: " + typefield.Tag.Get("dns")}
|
|
case `dns:"base64"`:
|
|
b64, e := fromBase64([]byte(s))
|
|
if e != nil {
|
|
return lenmsg, e
|
|
}
|
|
copy(msg[off:off+len(b64)], b64)
|
|
off += len(b64)
|
|
case `dns:"domain-name"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, 1 and 2 or used for addresses
|
|
x := val.Field(2).Uint()
|
|
if x == 1 || x == 2 {
|
|
continue
|
|
}
|
|
}
|
|
if off, err = PackDomainName(s, msg, off, compression, false && compress); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case `dns:"cdomain-name"`:
|
|
if off, err = PackDomainName(s, msg, off, compression, true && compress); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case `dns:"size-base32"`:
|
|
// This is purely for NSEC3 atm, the previous byte must
|
|
// holds the length of the encoded string. As NSEC3
|
|
// is only defined to SHA1, the hashlength is 20 (160 bits)
|
|
msg[off-1] = 20
|
|
fallthrough
|
|
case `dns:"base32"`:
|
|
b32, e := fromBase32([]byte(s))
|
|
if e != nil {
|
|
return lenmsg, e
|
|
}
|
|
copy(msg[off:off+len(b32)], b32)
|
|
off += len(b32)
|
|
case `dns:"size-hex"`:
|
|
fallthrough
|
|
case `dns:"hex"`:
|
|
// There is no length encoded here
|
|
h, e := hex.DecodeString(s)
|
|
if e != nil {
|
|
return lenmsg, e
|
|
}
|
|
if off+hex.DecodedLen(len(s)) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing hex"}
|
|
}
|
|
copy(msg[off:off+hex.DecodedLen(len(s))], h)
|
|
off += hex.DecodedLen(len(s))
|
|
case `dns:"size"`:
|
|
// the size is already encoded in the RR, we can safely use the
|
|
// length of string. String is RAW (not encoded in hex, nor base64)
|
|
copy(msg[off:off+len(s)], s)
|
|
off += len(s)
|
|
case `dns:"octet"`:
|
|
bytesTmp := make([]byte, 256)
|
|
off, err = packOctetString(fv.String(), msg, off, bytesTmp)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case `dns:"txt"`:
|
|
fallthrough
|
|
case "":
|
|
if txtTmp == nil {
|
|
txtTmp = make([]byte, 256*4+1)
|
|
}
|
|
off, err = packTxtString(fv.String(), msg, off, txtTmp)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
}
|
|
}
|
|
}
|
|
return off, nil
|
|
}
|
|
|
|
func structValue(any interface{}) reflect.Value {
|
|
return reflect.ValueOf(any).Elem()
|
|
}
|
|
|
|
// PackStruct packs any structure to wire format.
|
|
func PackStruct(any interface{}, msg []byte, off int) (off1 int, err error) {
|
|
off, err = packStructValue(structValue(any), msg, off, nil, false)
|
|
return off, err
|
|
}
|
|
|
|
func packStructCompress(any interface{}, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error) {
|
|
off, err = packStructValue(structValue(any), msg, off, compression, compress)
|
|
return off, err
|
|
}
|
|
|
|
// Unpack a reflect.StructValue from msg.
|
|
// Same restrictions as packStructValue.
|
|
func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, err error) {
|
|
lenmsg := len(msg)
|
|
for i := 0; i < val.NumField(); i++ {
|
|
if off > lenmsg {
|
|
return lenmsg, &Error{"bad offset unpacking"}
|
|
}
|
|
switch fv := val.Field(i); fv.Kind() {
|
|
default:
|
|
return lenmsg, &Error{err: "bad kind unpacking"}
|
|
case reflect.Interface:
|
|
// PrivateRR is the only RR implementation that has interface field.
|
|
// therefore it's expected that this interface would be PrivateRdata
|
|
switch data := fv.Interface().(type) {
|
|
case PrivateRdata:
|
|
n, err := data.Unpack(msg[off:])
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
off += n
|
|
default:
|
|
return lenmsg, &Error{err: "bad kind interface unpacking"}
|
|
}
|
|
case reflect.Slice:
|
|
switch val.Type().Field(i).Tag {
|
|
default:
|
|
return lenmsg, &Error{"bad tag unpacking slice: " + val.Type().Field(i).Tag.Get("dns")}
|
|
case `dns:"domain-name"`:
|
|
// HIP record slice of name (or none)
|
|
var servers []string
|
|
var s string
|
|
for off < lenmsg {
|
|
s, off, err = UnpackDomainName(msg, off)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
servers = append(servers, s)
|
|
}
|
|
fv.Set(reflect.ValueOf(servers))
|
|
case `dns:"txt"`:
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
var txt []string
|
|
txt, off, err = unpackTxt(msg, off)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
fv.Set(reflect.ValueOf(txt))
|
|
case `dns:"opt"`: // edns0
|
|
if off == lenmsg {
|
|
// This is an EDNS0 (OPT Record) with no rdata
|
|
// We can safely return here.
|
|
break
|
|
}
|
|
var edns []EDNS0
|
|
Option:
|
|
code := uint16(0)
|
|
if off+4 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking opt"}
|
|
}
|
|
code, off = unpackUint16(msg, off)
|
|
optlen, off1 := unpackUint16(msg, off)
|
|
if off1+int(optlen) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking opt"}
|
|
}
|
|
switch code {
|
|
case EDNS0NSID:
|
|
e := new(EDNS0_NSID)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0SUBNET, EDNS0SUBNETDRAFT:
|
|
e := new(EDNS0_SUBNET)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
if code == EDNS0SUBNETDRAFT {
|
|
e.DraftOption = true
|
|
}
|
|
case EDNS0UL:
|
|
e := new(EDNS0_UL)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0LLQ:
|
|
e := new(EDNS0_LLQ)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0DAU:
|
|
e := new(EDNS0_DAU)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0DHU:
|
|
e := new(EDNS0_DHU)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0N3U:
|
|
e := new(EDNS0_N3U)
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
default:
|
|
e := new(EDNS0_LOCAL)
|
|
e.Code = code
|
|
if err := e.unpack(msg[off1 : off1+int(optlen)]); err != nil {
|
|
return lenmsg, err
|
|
}
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
}
|
|
if off < lenmsg {
|
|
goto Option
|
|
}
|
|
fv.Set(reflect.ValueOf(edns))
|
|
case `dns:"a"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, must be 1
|
|
if val.Field(2).Uint() != 1 {
|
|
continue
|
|
}
|
|
}
|
|
if off == lenmsg {
|
|
break // dyn. update
|
|
}
|
|
if off+net.IPv4len > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking a"}
|
|
}
|
|
fv.Set(reflect.ValueOf(net.IPv4(msg[off], msg[off+1], msg[off+2], msg[off+3])))
|
|
off += net.IPv4len
|
|
case `dns:"aaaa"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, must be 2
|
|
if val.Field(2).Uint() != 2 {
|
|
continue
|
|
}
|
|
}
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
if off+net.IPv6len > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking aaaa"}
|
|
}
|
|
fv.Set(reflect.ValueOf(net.IP{msg[off], msg[off+1], msg[off+2], msg[off+3], msg[off+4],
|
|
msg[off+5], msg[off+6], msg[off+7], msg[off+8], msg[off+9], msg[off+10],
|
|
msg[off+11], msg[off+12], msg[off+13], msg[off+14], msg[off+15]}))
|
|
off += net.IPv6len
|
|
case `dns:"wks"`:
|
|
// Rest of the record is the bitmap
|
|
var serv []uint16
|
|
j := 0
|
|
for off < lenmsg {
|
|
if off+1 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking wks"}
|
|
}
|
|
b := msg[off]
|
|
// Check the bits one by one, and set the type
|
|
if b&0x80 == 0x80 {
|
|
serv = append(serv, uint16(j*8+0))
|
|
}
|
|
if b&0x40 == 0x40 {
|
|
serv = append(serv, uint16(j*8+1))
|
|
}
|
|
if b&0x20 == 0x20 {
|
|
serv = append(serv, uint16(j*8+2))
|
|
}
|
|
if b&0x10 == 0x10 {
|
|
serv = append(serv, uint16(j*8+3))
|
|
}
|
|
if b&0x8 == 0x8 {
|
|
serv = append(serv, uint16(j*8+4))
|
|
}
|
|
if b&0x4 == 0x4 {
|
|
serv = append(serv, uint16(j*8+5))
|
|
}
|
|
if b&0x2 == 0x2 {
|
|
serv = append(serv, uint16(j*8+6))
|
|
}
|
|
if b&0x1 == 0x1 {
|
|
serv = append(serv, uint16(j*8+7))
|
|
}
|
|
j++
|
|
off++
|
|
}
|
|
fv.Set(reflect.ValueOf(serv))
|
|
case `dns:"nsec"`: // NSEC/NSEC3
|
|
if off == len(msg) {
|
|
break
|
|
}
|
|
// Rest of the record is the type bitmap
|
|
var nsec []uint16
|
|
length := 0
|
|
window := 0
|
|
lastwindow := -1
|
|
for off < len(msg) {
|
|
if off+2 > len(msg) {
|
|
return 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 len(msg), &Error{err: "out of order NSEC block"}
|
|
}
|
|
if length == 0 {
|
|
// RFC 4034: Blocks with no types present MUST NOT be included.
|
|
return len(msg), &Error{err: "empty NSEC block"}
|
|
}
|
|
if length > 32 {
|
|
return len(msg), &Error{err: "NSEC block too long"}
|
|
}
|
|
if off+length > len(msg) {
|
|
return 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
|
|
}
|
|
fv.Set(reflect.ValueOf(nsec))
|
|
}
|
|
case reflect.Struct:
|
|
off, err = unpackStructValue(fv, msg, off)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
if val.Type().Field(i).Name == "Hdr" {
|
|
lenrd := off + int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
if lenrd > lenmsg {
|
|
return lenmsg, &Error{err: "overflowing header size"}
|
|
}
|
|
msg = msg[:lenrd]
|
|
lenmsg = len(msg)
|
|
}
|
|
case reflect.Uint8:
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
if off+1 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking uint8"}
|
|
}
|
|
fv.SetUint(uint64(uint8(msg[off])))
|
|
off++
|
|
case reflect.Uint16:
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
var i uint16
|
|
if off+2 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking uint16"}
|
|
}
|
|
i, off = unpackUint16(msg, off)
|
|
fv.SetUint(uint64(i))
|
|
case reflect.Uint32:
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
if off+4 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking uint32"}
|
|
}
|
|
fv.SetUint(uint64(uint32(msg[off])<<24 | uint32(msg[off+1])<<16 | uint32(msg[off+2])<<8 | uint32(msg[off+3])))
|
|
off += 4
|
|
case reflect.Uint64:
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
switch val.Type().Field(i).Tag {
|
|
default:
|
|
if off+8 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking uint64"}
|
|
}
|
|
fv.SetUint(uint64(uint64(msg[off])<<56 | uint64(msg[off+1])<<48 | uint64(msg[off+2])<<40 |
|
|
uint64(msg[off+3])<<32 | uint64(msg[off+4])<<24 | uint64(msg[off+5])<<16 | uint64(msg[off+6])<<8 | uint64(msg[off+7])))
|
|
off += 8
|
|
case `dns:"uint48"`:
|
|
// Used in TSIG where the last 48 bits are occupied, so for now, assume a uint48 (6 bytes)
|
|
if off+6 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking uint64 as uint48"}
|
|
}
|
|
fv.SetUint(uint64(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
|
|
}
|
|
case reflect.String:
|
|
var s string
|
|
if off == lenmsg {
|
|
break
|
|
}
|
|
switch val.Type().Field(i).Tag {
|
|
default:
|
|
return lenmsg, &Error{"bad tag unpacking string: " + val.Type().Field(i).Tag.Get("dns")}
|
|
case `dns:"octet"`:
|
|
s = string(msg[off:])
|
|
off = lenmsg
|
|
case `dns:"hex"`:
|
|
hexend := lenmsg
|
|
if val.FieldByName("Hdr").FieldByName("Rrtype").Uint() == uint64(TypeHIP) {
|
|
hexend = off + int(val.FieldByName("HitLength").Uint())
|
|
}
|
|
if hexend > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking HIP hex"}
|
|
}
|
|
s = hex.EncodeToString(msg[off:hexend])
|
|
off = hexend
|
|
case `dns:"base64"`:
|
|
// Rest of the RR is base64 encoded value
|
|
b64end := lenmsg
|
|
if val.FieldByName("Hdr").FieldByName("Rrtype").Uint() == uint64(TypeHIP) {
|
|
b64end = off + int(val.FieldByName("PublicKeyLength").Uint())
|
|
}
|
|
if b64end > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking HIP base64"}
|
|
}
|
|
s = toBase64(msg[off:b64end])
|
|
off = b64end
|
|
case `dns:"cdomain-name"`:
|
|
fallthrough
|
|
case `dns:"domain-name"`:
|
|
if val.Type().String() == "dns.IPSECKEY" {
|
|
// Field(2) is GatewayType, 1 and 2 or used for addresses
|
|
x := val.Field(2).Uint()
|
|
if x == 1 || x == 2 {
|
|
continue
|
|
}
|
|
}
|
|
if off == lenmsg && int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint()) == 0 {
|
|
// zero rdata is ok for dyn updates, but only if rdlength is 0
|
|
break
|
|
}
|
|
s, off, err = UnpackDomainName(msg, off)
|
|
if err != nil {
|
|
return lenmsg, err
|
|
}
|
|
case `dns:"size-base32"`:
|
|
var size int
|
|
switch val.Type().Name() {
|
|
case "NSEC3":
|
|
switch val.Type().Field(i).Name {
|
|
case "NextDomain":
|
|
name := val.FieldByName("HashLength")
|
|
size = int(name.Uint())
|
|
}
|
|
}
|
|
if off+size > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking base32"}
|
|
}
|
|
s = toBase32(msg[off : off+size])
|
|
off += size
|
|
case `dns:"size-hex"`:
|
|
// a "size" string, but it must be encoded in hex in the string
|
|
var size int
|
|
switch val.Type().Name() {
|
|
case "NSEC3":
|
|
switch val.Type().Field(i).Name {
|
|
case "Salt":
|
|
name := val.FieldByName("SaltLength")
|
|
size = int(name.Uint())
|
|
case "NextDomain":
|
|
name := val.FieldByName("HashLength")
|
|
size = int(name.Uint())
|
|
}
|
|
case "TSIG":
|
|
switch val.Type().Field(i).Name {
|
|
case "MAC":
|
|
name := val.FieldByName("MACSize")
|
|
size = int(name.Uint())
|
|
case "OtherData":
|
|
name := val.FieldByName("OtherLen")
|
|
size = int(name.Uint())
|
|
}
|
|
}
|
|
if off+size > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking hex"}
|
|
}
|
|
s = hex.EncodeToString(msg[off : off+size])
|
|
off += size
|
|
case `dns:"txt"`:
|
|
fallthrough
|
|
case "":
|
|
s, off, err = unpackTxtString(msg, off)
|
|
}
|
|
fv.SetString(s)
|
|
}
|
|
}
|
|
return off, nil
|
|
}
|
|
|
|
// Helpers for dealing with escaped bytes
|
|
func isDigit(b byte) bool { return b >= '0' && b <= '9' }
|
|
|
|
func dddToByte(s []byte) byte {
|
|
return byte((s[0]-'0')*100 + (s[1]-'0')*10 + (s[2] - '0'))
|
|
}
|
|
|
|
// UnpackStruct unpacks a binary message from offset off to the interface
|
|
// value given.
|
|
func UnpackStruct(any interface{}, msg []byte, off int) (int, error) {
|
|
return unpackStructValue(structValue(any), msg, off)
|
|
}
|
|
|
|
// Helper function for packing and unpacking
|
|
func intToBytes(i *big.Int, length int) []byte {
|
|
buf := i.Bytes()
|
|
if len(buf) < length {
|
|
b := make([]byte, length)
|
|
copy(b[length-len(buf):], buf)
|
|
return b
|
|
}
|
|
return buf
|
|
}
|
|
|
|
func unpackUint16(msg []byte, off int) (uint16, int) {
|
|
return uint16(msg[off])<<8 | uint16(msg[off+1]), off + 2
|
|
}
|
|
|
|
func packUint16(i uint16) (byte, byte) {
|
|
return byte(i >> 8), byte(i)
|
|
}
|
|
|
|
func toBase32(b []byte) string {
|
|
return base32.HexEncoding.EncodeToString(b)
|
|
}
|
|
|
|
func fromBase32(s []byte) (buf []byte, err error) {
|
|
buflen := base32.HexEncoding.DecodedLen(len(s))
|
|
buf = make([]byte, buflen)
|
|
n, err := base32.HexEncoding.Decode(buf, s)
|
|
buf = buf[:n]
|
|
return
|
|
}
|
|
|
|
func toBase64(b []byte) string {
|
|
return base64.StdEncoding.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
|
|
}
|
|
|
|
// PackRR packs a resource record rr into msg[off:].
|
|
// See PackDomainName for documentation about the compression.
|
|
func PackRR(rr RR, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error) {
|
|
if rr == nil {
|
|
return len(msg), &Error{err: "nil rr"}
|
|
}
|
|
|
|
off1, err = packStructCompress(rr, msg, off, compression, compress)
|
|
if err != nil {
|
|
return len(msg), err
|
|
}
|
|
if rawSetRdlength(msg, off, off1) {
|
|
return off1, nil
|
|
}
|
|
return off, ErrRdata
|
|
}
|
|
|
|
// UnpackRR unpacks msg[off:] into an RR.
|
|
func UnpackRR(msg []byte, off int) (rr RR, off1 int, err error) {
|
|
// unpack just the header, to find the rr type and length
|
|
var h RR_Header
|
|
off0 := off
|
|
if off, err = UnpackStruct(&h, msg, off); err != nil {
|
|
return nil, len(msg), err
|
|
}
|
|
end := off + int(h.Rdlength)
|
|
// make an rr of that type and re-unpack.
|
|
mk, known := TypeToRR[h.Rrtype]
|
|
if !known {
|
|
rr = new(RFC3597)
|
|
} else {
|
|
rr = mk()
|
|
}
|
|
off, err = UnpackStruct(rr, msg, off0)
|
|
if off != end {
|
|
return &h, end, &Error{err: "bad rdlength"}
|
|
}
|
|
return rr, off, err
|
|
}
|
|
|
|
// unpackRRslice unpacks msg[off:] into an []RR.
|
|
// If we cannot unpack the whole array, then it will return nil
|
|
func unpackRRslice(l int, msg []byte, off int) (dst1 []RR, off1 int, err error) {
|
|
var r RR
|
|
// Optimistically make dst be the length that was sent
|
|
dst := make([]RR, 0, l)
|
|
for i := 0; i < l; i++ {
|
|
off1 := off
|
|
r, off, err = UnpackRR(msg, off)
|
|
if err != nil {
|
|
off = len(msg)
|
|
break
|
|
}
|
|
// If offset does not increase anymore, l is a lie
|
|
if off1 == off {
|
|
l = i
|
|
break
|
|
}
|
|
dst = append(dst, r)
|
|
}
|
|
if err != nil && off == len(msg) {
|
|
dst = nil
|
|
}
|
|
return dst, off, err
|
|
}
|
|
|
|
// Reverse a map
|
|
func reverseInt8(m map[uint8]string) map[string]uint8 {
|
|
n := make(map[string]uint8)
|
|
for u, s := range m {
|
|
n[s] = u
|
|
}
|
|
return n
|
|
}
|
|
|
|
func reverseInt16(m map[uint16]string) map[string]uint16 {
|
|
n := make(map[string]uint16)
|
|
for u, s := range m {
|
|
n[s] = u
|
|
}
|
|
return n
|
|
}
|
|
|
|
func reverseInt(m map[int]string) map[string]int {
|
|
n := make(map[string]int)
|
|
for u, s := range m {
|
|
n[s] = u
|
|
}
|
|
return n
|
|
}
|
|
|
|
// Convert a MsgHdr to a string, with dig-like headers:
|
|
//
|
|
//;; opcode: QUERY, status: NOERROR, id: 48404
|
|
//
|
|
//;; flags: qr aa rd ra;
|
|
func (h *MsgHdr) String() string {
|
|
if h == nil {
|
|
return "<nil> MsgHdr"
|
|
}
|
|
|
|
s := ";; opcode: " + OpcodeToString[h.Opcode]
|
|
s += ", status: " + RcodeToString[h.Rcode]
|
|
s += ", id: " + strconv.Itoa(int(h.Id)) + "\n"
|
|
|
|
s += ";; flags:"
|
|
if h.Response {
|
|
s += " qr"
|
|
}
|
|
if h.Authoritative {
|
|
s += " aa"
|
|
}
|
|
if h.Truncated {
|
|
s += " tc"
|
|
}
|
|
if h.RecursionDesired {
|
|
s += " rd"
|
|
}
|
|
if h.RecursionAvailable {
|
|
s += " ra"
|
|
}
|
|
if h.Zero { // Hmm
|
|
s += " z"
|
|
}
|
|
if h.AuthenticatedData {
|
|
s += " ad"
|
|
}
|
|
if h.CheckingDisabled {
|
|
s += " cd"
|
|
}
|
|
|
|
s += ";"
|
|
return s
|
|
}
|
|
|
|
// Pack packs a Msg: it is converted to to wire format.
|
|
// If the dns.Compress is true the message will be in compressed wire format.
|
|
func (dns *Msg) Pack() (msg []byte, err error) {
|
|
return dns.PackBuffer(nil)
|
|
}
|
|
|
|
// PackBuffer packs a Msg, using the given buffer buf. If buf is too small
|
|
// a new buffer is allocated.
|
|
func (dns *Msg) PackBuffer(buf []byte) (msg []byte, err error) {
|
|
var dh Header
|
|
var compression map[string]int
|
|
if dns.Compress {
|
|
compression = make(map[string]int) // Compression pointer mappings
|
|
}
|
|
|
|
if dns.Rcode < 0 || dns.Rcode > 0xFFF {
|
|
return nil, ErrRcode
|
|
}
|
|
if dns.Rcode > 0xF {
|
|
// Regular RCODE field is 4 bits
|
|
opt := dns.IsEdns0()
|
|
if opt == nil {
|
|
return nil, ErrExtendedRcode
|
|
}
|
|
opt.SetExtendedRcode(uint8(dns.Rcode >> 4))
|
|
dns.Rcode &= 0xF
|
|
}
|
|
|
|
// Convert convenient Msg into wire-like Header.
|
|
dh.Id = dns.Id
|
|
dh.Bits = uint16(dns.Opcode)<<11 | uint16(dns.Rcode)
|
|
if dns.Response {
|
|
dh.Bits |= _QR
|
|
}
|
|
if dns.Authoritative {
|
|
dh.Bits |= _AA
|
|
}
|
|
if dns.Truncated {
|
|
dh.Bits |= _TC
|
|
}
|
|
if dns.RecursionDesired {
|
|
dh.Bits |= _RD
|
|
}
|
|
if dns.RecursionAvailable {
|
|
dh.Bits |= _RA
|
|
}
|
|
if dns.Zero {
|
|
dh.Bits |= _Z
|
|
}
|
|
if dns.AuthenticatedData {
|
|
dh.Bits |= _AD
|
|
}
|
|
if dns.CheckingDisabled {
|
|
dh.Bits |= _CD
|
|
}
|
|
|
|
// Prepare variable sized arrays.
|
|
question := dns.Question
|
|
answer := dns.Answer
|
|
ns := dns.Ns
|
|
extra := dns.Extra
|
|
|
|
dh.Qdcount = uint16(len(question))
|
|
dh.Ancount = uint16(len(answer))
|
|
dh.Nscount = uint16(len(ns))
|
|
dh.Arcount = uint16(len(extra))
|
|
|
|
// We need the uncompressed length here, because we first pack it and then compress it.
|
|
msg = buf
|
|
compress := dns.Compress
|
|
dns.Compress = false
|
|
if packLen := dns.Len() + 1; len(msg) < packLen {
|
|
msg = make([]byte, packLen)
|
|
}
|
|
dns.Compress = compress
|
|
|
|
// Pack it in: header and then the pieces.
|
|
off := 0
|
|
off, err = packStructCompress(&dh, msg, off, compression, dns.Compress)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
for i := 0; i < len(question); i++ {
|
|
off, err = packStructCompress(&question[i], msg, off, compression, dns.Compress)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
for i := 0; i < len(answer); i++ {
|
|
off, err = PackRR(answer[i], msg, off, compression, dns.Compress)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
for i := 0; i < len(ns); i++ {
|
|
off, err = PackRR(ns[i], msg, off, compression, dns.Compress)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
for i := 0; i < len(extra); i++ {
|
|
off, err = PackRR(extra[i], msg, off, compression, dns.Compress)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
return msg[:off], nil
|
|
}
|
|
|
|
// Unpack unpacks a binary message to a Msg structure.
|
|
func (dns *Msg) Unpack(msg []byte) (err error) {
|
|
// Header.
|
|
var dh Header
|
|
off := 0
|
|
if off, err = UnpackStruct(&dh, msg, off); err != nil {
|
|
return err
|
|
}
|
|
dns.Id = dh.Id
|
|
dns.Response = (dh.Bits & _QR) != 0
|
|
dns.Opcode = int(dh.Bits>>11) & 0xF
|
|
dns.Authoritative = (dh.Bits & _AA) != 0
|
|
dns.Truncated = (dh.Bits & _TC) != 0
|
|
dns.RecursionDesired = (dh.Bits & _RD) != 0
|
|
dns.RecursionAvailable = (dh.Bits & _RA) != 0
|
|
dns.Zero = (dh.Bits & _Z) != 0
|
|
dns.AuthenticatedData = (dh.Bits & _AD) != 0
|
|
dns.CheckingDisabled = (dh.Bits & _CD) != 0
|
|
dns.Rcode = int(dh.Bits & 0xF)
|
|
|
|
// Optimistically use the count given to us in the header
|
|
dns.Question = make([]Question, 0, int(dh.Qdcount))
|
|
|
|
var q Question
|
|
for i := 0; i < int(dh.Qdcount); i++ {
|
|
off1 := off
|
|
off, err = UnpackStruct(&q, msg, off)
|
|
if err != nil {
|
|
// Even if Truncated is set, we only will set ErrTruncated if we
|
|
// actually got the questions
|
|
return err
|
|
}
|
|
if off1 == off { // Offset does not increase anymore, dh.Qdcount is a lie!
|
|
dh.Qdcount = uint16(i)
|
|
break
|
|
}
|
|
dns.Question = append(dns.Question, q)
|
|
}
|
|
|
|
dns.Answer, off, err = unpackRRslice(int(dh.Ancount), msg, off)
|
|
// The header counts might have been wrong so we need to update it
|
|
dh.Ancount = uint16(len(dns.Answer))
|
|
if err == nil {
|
|
dns.Ns, off, err = unpackRRslice(int(dh.Nscount), msg, off)
|
|
}
|
|
// The header counts might have been wrong so we need to update it
|
|
dh.Nscount = uint16(len(dns.Ns))
|
|
if err == nil {
|
|
dns.Extra, off, err = unpackRRslice(int(dh.Arcount), msg, off)
|
|
}
|
|
// The header counts might have been wrong so we need to update it
|
|
dh.Arcount = uint16(len(dns.Extra))
|
|
if off != len(msg) {
|
|
// TODO(miek) make this an error?
|
|
// use PackOpt to let people tell how detailed the error reporting should be?
|
|
// println("dns: extra bytes in dns packet", off, "<", len(msg))
|
|
} else if dns.Truncated {
|
|
// Whether we ran into a an error or not, we want to return that it
|
|
// was truncated
|
|
err = ErrTruncated
|
|
}
|
|
return err
|
|
}
|
|
|
|
// Convert a complete message to a string with dig-like output.
|
|
func (dns *Msg) String() string {
|
|
if dns == nil {
|
|
return "<nil> MsgHdr"
|
|
}
|
|
s := dns.MsgHdr.String() + " "
|
|
s += "QUERY: " + strconv.Itoa(len(dns.Question)) + ", "
|
|
s += "ANSWER: " + strconv.Itoa(len(dns.Answer)) + ", "
|
|
s += "AUTHORITY: " + strconv.Itoa(len(dns.Ns)) + ", "
|
|
s += "ADDITIONAL: " + strconv.Itoa(len(dns.Extra)) + "\n"
|
|
if len(dns.Question) > 0 {
|
|
s += "\n;; QUESTION SECTION:\n"
|
|
for i := 0; i < len(dns.Question); i++ {
|
|
s += dns.Question[i].String() + "\n"
|
|
}
|
|
}
|
|
if len(dns.Answer) > 0 {
|
|
s += "\n;; ANSWER SECTION:\n"
|
|
for i := 0; i < len(dns.Answer); i++ {
|
|
if dns.Answer[i] != nil {
|
|
s += dns.Answer[i].String() + "\n"
|
|
}
|
|
}
|
|
}
|
|
if len(dns.Ns) > 0 {
|
|
s += "\n;; AUTHORITY SECTION:\n"
|
|
for i := 0; i < len(dns.Ns); i++ {
|
|
if dns.Ns[i] != nil {
|
|
s += dns.Ns[i].String() + "\n"
|
|
}
|
|
}
|
|
}
|
|
if len(dns.Extra) > 0 {
|
|
s += "\n;; ADDITIONAL SECTION:\n"
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
if dns.Extra[i] != nil {
|
|
s += dns.Extra[i].String() + "\n"
|
|
}
|
|
}
|
|
}
|
|
return s
|
|
}
|
|
|
|
// Len returns the message length when in (un)compressed wire format.
|
|
// If dns.Compress is true compression it is taken into account. Len()
|
|
// is provided to be a faster way to get the size of the resulting packet,
|
|
// than packing it, measuring the size and discarding the buffer.
|
|
func (dns *Msg) Len() int {
|
|
// We always return one more than needed.
|
|
l := 12 // Message header is always 12 bytes
|
|
var compression map[string]int
|
|
if dns.Compress {
|
|
compression = make(map[string]int)
|
|
}
|
|
for i := 0; i < len(dns.Question); i++ {
|
|
l += dns.Question[i].len()
|
|
if dns.Compress {
|
|
compressionLenHelper(compression, dns.Question[i].Name)
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Answer); i++ {
|
|
l += dns.Answer[i].len()
|
|
if dns.Compress {
|
|
k, ok := compressionLenSearch(compression, dns.Answer[i].Header().Name)
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelper(compression, dns.Answer[i].Header().Name)
|
|
k, ok = compressionLenSearchType(compression, dns.Answer[i])
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelperType(compression, dns.Answer[i])
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Ns); i++ {
|
|
l += dns.Ns[i].len()
|
|
if dns.Compress {
|
|
k, ok := compressionLenSearch(compression, dns.Ns[i].Header().Name)
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelper(compression, dns.Ns[i].Header().Name)
|
|
k, ok = compressionLenSearchType(compression, dns.Ns[i])
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelperType(compression, dns.Ns[i])
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
l += dns.Extra[i].len()
|
|
if dns.Compress {
|
|
k, ok := compressionLenSearch(compression, dns.Extra[i].Header().Name)
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelper(compression, dns.Extra[i].Header().Name)
|
|
k, ok = compressionLenSearchType(compression, dns.Extra[i])
|
|
if ok {
|
|
l += 1 - k
|
|
}
|
|
compressionLenHelperType(compression, dns.Extra[i])
|
|
}
|
|
}
|
|
return l
|
|
}
|
|
|
|
// Put the parts of the name in the compression map.
|
|
func compressionLenHelper(c map[string]int, s string) {
|
|
pref := ""
|
|
lbs := Split(s)
|
|
for j := len(lbs) - 1; j >= 0; j-- {
|
|
pref = s[lbs[j]:]
|
|
if _, ok := c[pref]; !ok {
|
|
c[pref] = len(pref)
|
|
}
|
|
}
|
|
}
|
|
|
|
// Look for each part in the compression map and returns its length,
|
|
// keep on searching so we get the longest match.
|
|
func compressionLenSearch(c map[string]int, s string) (int, bool) {
|
|
off := 0
|
|
end := false
|
|
if s == "" { // don't bork on bogus data
|
|
return 0, false
|
|
}
|
|
for {
|
|
if _, ok := c[s[off:]]; ok {
|
|
return len(s[off:]), true
|
|
}
|
|
if end {
|
|
break
|
|
}
|
|
off, end = NextLabel(s, off)
|
|
}
|
|
return 0, false
|
|
}
|
|
|
|
// TODO(miek): should add all types, because the all can be *used* for compression.
|
|
func compressionLenHelperType(c map[string]int, r RR) {
|
|
switch x := r.(type) {
|
|
case *NS:
|
|
compressionLenHelper(c, x.Ns)
|
|
case *MX:
|
|
compressionLenHelper(c, x.Mx)
|
|
case *CNAME:
|
|
compressionLenHelper(c, x.Target)
|
|
case *PTR:
|
|
compressionLenHelper(c, x.Ptr)
|
|
case *SOA:
|
|
compressionLenHelper(c, x.Ns)
|
|
compressionLenHelper(c, x.Mbox)
|
|
case *MB:
|
|
compressionLenHelper(c, x.Mb)
|
|
case *MG:
|
|
compressionLenHelper(c, x.Mg)
|
|
case *MR:
|
|
compressionLenHelper(c, x.Mr)
|
|
case *MF:
|
|
compressionLenHelper(c, x.Mf)
|
|
case *MD:
|
|
compressionLenHelper(c, x.Md)
|
|
case *RT:
|
|
compressionLenHelper(c, x.Host)
|
|
case *MINFO:
|
|
compressionLenHelper(c, x.Rmail)
|
|
compressionLenHelper(c, x.Email)
|
|
case *AFSDB:
|
|
compressionLenHelper(c, x.Hostname)
|
|
}
|
|
}
|
|
|
|
// Only search on compressing these types.
|
|
func compressionLenSearchType(c map[string]int, r RR) (int, bool) {
|
|
switch x := r.(type) {
|
|
case *NS:
|
|
return compressionLenSearch(c, x.Ns)
|
|
case *MX:
|
|
return compressionLenSearch(c, x.Mx)
|
|
case *CNAME:
|
|
return compressionLenSearch(c, x.Target)
|
|
case *PTR:
|
|
return compressionLenSearch(c, x.Ptr)
|
|
case *SOA:
|
|
k, ok := compressionLenSearch(c, x.Ns)
|
|
k1, ok1 := compressionLenSearch(c, x.Mbox)
|
|
if !ok && !ok1 {
|
|
return 0, false
|
|
}
|
|
return k + k1, true
|
|
case *MB:
|
|
return compressionLenSearch(c, x.Mb)
|
|
case *MG:
|
|
return compressionLenSearch(c, x.Mg)
|
|
case *MR:
|
|
return compressionLenSearch(c, x.Mr)
|
|
case *MF:
|
|
return compressionLenSearch(c, x.Mf)
|
|
case *MD:
|
|
return compressionLenSearch(c, x.Md)
|
|
case *RT:
|
|
return compressionLenSearch(c, x.Host)
|
|
case *MINFO:
|
|
k, ok := compressionLenSearch(c, x.Rmail)
|
|
k1, ok1 := compressionLenSearch(c, x.Email)
|
|
if !ok && !ok1 {
|
|
return 0, false
|
|
}
|
|
return k + k1, true
|
|
case *AFSDB:
|
|
return compressionLenSearch(c, x.Hostname)
|
|
}
|
|
return 0, false
|
|
}
|
|
|
|
// id returns a 16 bits random number to be used as a
|
|
// message id. The random provided should be good enough.
|
|
func id() uint16 {
|
|
return uint16(rand.Int()) ^ uint16(time.Now().Nanosecond())
|
|
}
|
|
|
|
// Copy returns a new RR which is a deep-copy of r.
|
|
func Copy(r RR) RR {
|
|
r1 := r.copy()
|
|
return r1
|
|
}
|
|
|
|
// Copy returns a new *Msg which is a deep-copy of dns.
|
|
func (dns *Msg) Copy() *Msg {
|
|
return dns.CopyTo(new(Msg))
|
|
}
|
|
|
|
// CopyTo copies the contents to the provided message using a deep-copy and returns the copy.
|
|
func (dns *Msg) CopyTo(r1 *Msg) *Msg {
|
|
r1.MsgHdr = dns.MsgHdr
|
|
r1.Compress = dns.Compress
|
|
|
|
if len(dns.Question) > 0 {
|
|
r1.Question = make([]Question, len(dns.Question))
|
|
copy(r1.Question, dns.Question) // TODO(miek): Question is an immutable value, ok to do a shallow-copy
|
|
}
|
|
|
|
rrArr := make([]RR, len(dns.Answer)+len(dns.Ns)+len(dns.Extra))
|
|
var rri int
|
|
|
|
if len(dns.Answer) > 0 {
|
|
rrbegin := rri
|
|
for i := 0; i < len(dns.Answer); i++ {
|
|
rrArr[rri] = dns.Answer[i].copy()
|
|
rri++
|
|
}
|
|
r1.Answer = rrArr[rrbegin:rri:rri]
|
|
}
|
|
|
|
if len(dns.Ns) > 0 {
|
|
rrbegin := rri
|
|
for i := 0; i < len(dns.Ns); i++ {
|
|
rrArr[rri] = dns.Ns[i].copy()
|
|
rri++
|
|
}
|
|
r1.Ns = rrArr[rrbegin:rri:rri]
|
|
}
|
|
|
|
if len(dns.Extra) > 0 {
|
|
rrbegin := rri
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
rrArr[rri] = dns.Extra[i].copy()
|
|
rri++
|
|
}
|
|
r1.Extra = rrArr[rrbegin:rri:rri]
|
|
}
|
|
|
|
return r1
|
|
}
|