mirror of
https://github.com/miekg/dns.git
synced 2025-08-11 20:16:58 +02:00
b6a2d1fb5e
Empty or no rdata is allowed for dynamic updates, so test if this works for packing/unpacking. It only fails for TSIG (which is never seen in zone files), SOA (which is not seen like this in dyn. updates) and WKS (just an old record).
1666 lines
44 KiB
Go
1666 lines
44 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Extensions of the original work are copyright (c) 2011 Miek Gieben
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// 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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"fmt"
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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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ErrFqdn error = &Error{err: "domain must be fully qualified"}
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ErrId error = &Error{err: "id mismatch"}
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ErrRdata error = &Error{err: "bad rdata"}
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ErrBuf error = &Error{err: "buffer size too small"}
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ErrShortRead error = &Error{err: "short read"}
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ErrConn error = &Error{err: "conn holds both UDP and TCP connection"}
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ErrConnEmpty error = &Error{err: "conn has no connection"}
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ErrServ error = &Error{err: "no servers could be reached"}
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ErrKey error = &Error{err: "bad key"}
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ErrPrivKey error = &Error{err: "bad private key"}
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ErrKeySize error = &Error{err: "bad key size"}
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ErrKeyAlg error = &Error{err: "bad key algorithm"}
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ErrAlg error = &Error{err: "bad algorithm"}
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ErrTime error = &Error{err: "bad time"}
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ErrNoSig error = &Error{err: "no signature found"}
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ErrSig error = &Error{err: "bad signature"}
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ErrSecret error = &Error{err: "no secrets defined"}
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ErrSigGen error = &Error{err: "bad signature generation"}
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ErrAuth error = &Error{err: "bad authentication"}
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ErrSoa error = &Error{err: "no SOA"}
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ErrRRset error = &Error{err: "bad rrset"}
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)
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// A manually-unpacked version of (id, bits).
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// This is in its own struct for easy printing.
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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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// 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.
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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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// Map of strings for each RR wire type.
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var TypeToString = map[uint16]string{
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TypeCNAME: "CNAME",
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TypeHINFO: "HINFO",
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TypeTLSA: "TLSA",
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TypeMB: "MB",
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TypeMG: "MG",
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TypeRP: "RP",
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TypeMD: "MD",
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TypeMF: "MF",
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TypeMINFO: "MINFO",
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TypeMR: "MR",
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TypeMX: "MX",
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TypeWKS: "WKS",
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TypeNS: "NS",
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TypeNULL: "NULL",
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TypeAFSDB: "AFSDB",
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TypeX25: "X25",
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TypeISDN: "ISDN",
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TypePTR: "PTR",
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TypeRT: "RT",
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TypeSOA: "SOA",
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TypeTXT: "TXT",
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TypeSRV: "SRV",
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TypeATMA: "ATMA",
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TypeNAPTR: "NAPTR",
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TypeKX: "KX",
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TypeCERT: "CERT",
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TypeDNAME: "DNAME",
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TypeA: "A",
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TypeAAAA: "AAAA",
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TypeLOC: "LOC",
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TypeOPT: "OPT",
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TypeDS: "DS",
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TypeDHCID: "DHCID",
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TypeHIP: "HIP",
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TypeNINFO: "NINFO",
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TypeRKEY: "RKEY",
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TypeCDS: "CDS",
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TypeCAA: "CAA",
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TypeIPSECKEY: "IPSECKEY",
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TypeSSHFP: "SSHFP",
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TypeRRSIG: "RRSIG",
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TypeNSEC: "NSEC",
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TypeDNSKEY: "DNSKEY",
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TypeNSEC3: "NSEC3",
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TypeNSEC3PARAM: "NSEC3PARAM",
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TypeTALINK: "TALINK",
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TypeSPF: "SPF",
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TypeNID: "NID",
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TypeL32: "L32",
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TypeL64: "L64",
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TypeLP: "LP",
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TypeUINFO: "UINFO",
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TypeUID: "UID",
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TypeGID: "GID",
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TypeUNSPEC: "UNSPEC",
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TypeEUI48: "EUI48",
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TypeEUI64: "EUI64",
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TypeTKEY: "TKEY", // Meta RR
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TypeTSIG: "TSIG", // Meta RR
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TypeAXFR: "AXFR", // Meta RR
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TypeIXFR: "IXFR", // Meta RR
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TypeANY: "ANY", // Meta RR
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TypeURI: "URI",
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TypeTA: "TA",
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TypeDLV: "DLV",
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}
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// Reverse, needed for string parsing.
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var StringToType = reverseInt16(TypeToString)
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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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// Map of 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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// Map of strings for opcodes.
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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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// Map of strings for rcodes.
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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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lenmsg := len(msg)
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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, nil
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}
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// If not fully qualified, error out
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if s[ls-1] != '.' {
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return lenmsg, ErrFqdn
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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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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, ErrBuf
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}
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// check for \DDD
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if i+2 < ls && bs[i] >= '0' && bs[i] <= '9' &&
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bs[i+1] >= '0' && bs[i+1] <= '9' &&
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bs[i+2] >= '0' && bs[i+2] <= '9' {
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bs[i] = byte((bs[i]-'0')*100 + (bs[i+1]-'0')*10 + (bs[i+2] - '0'))
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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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}
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continue
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}
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if bs[i] == '.' {
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if i-begin >= 1<<6 { // top two bits of length must be clear
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return lenmsg, 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, ErrBuf
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}
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msg[off] = byte(i - begin)
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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, ErrBuf
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}
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msg[off] = bs[j]
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off++
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}
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// Dont try to compress '.'
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if compression != nil && string(bs[begin:]) != "." {
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if p, ok := compression[string(bs[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[string(bs[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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begin = i + 1
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}
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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, 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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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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msg[off] = 0
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End:
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off++
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return off, 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) (s string, off1 int, err error) {
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s = ""
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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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if s == "" {
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return ".", off, nil
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}
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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 {
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case msg[j] == '.': // literal dots
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s += "\\."
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case msg[j] < 32: // unprintable use \DDD
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fallthrough
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case msg[j] >= 127:
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s += fmt.Sprintf("\\%03d", msg[j])
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default:
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s += string(msg[j])
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}
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}
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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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return s, off1, nil
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}
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// Pack a reflect.StructValue into msg. Struct members can only be uint8, uint16, uint32, string,
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// slices and other (often anonymous) structs.
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func packStructValue(val reflect.Value, msg []byte, off int, compression map[string]int, compress bool) (off1 int, err error) {
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lenmsg := len(msg)
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for i := 0; i < val.NumField(); i++ {
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switch fv := val.Field(i); fv.Kind() {
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default:
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return lenmsg, &Error{err: "bad kind packing"}
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case reflect.Slice:
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switch val.Type().Field(i).Tag {
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default:
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return lenmsg, &Error{"bad tag packing slice: " + val.Type().Field(i).Tag.Get("dns")}
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case `dns:"domain-name"`:
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for j := 0; j < val.Field(i).Len(); j++ {
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element := val.Field(i).Index(j).String()
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off, err = PackDomainName(element, msg, off, compression, false && compress)
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if err != nil {
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return lenmsg, err
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}
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}
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case `dns:"txt"`:
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for j := 0; j < val.Field(i).Len(); j++ {
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element := val.Field(i).Index(j).String()
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// Counted string: 1 byte length.
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if len(element) > 255 || off+1+len(element) > lenmsg {
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return lenmsg, &Error{err: "overflow packing txt"}
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}
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msg[off] = byte(len(element))
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off++
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for i := 0; i < len(element); i++ {
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msg[off+i] = element[i]
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}
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off += len(element)
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}
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case `dns:"opt"`: // edns
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for j := 0; j < val.Field(i).Len(); j++ {
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element := val.Field(i).Index(j).Interface()
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b, e := element.(EDNS0).pack()
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if e != nil {
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return lenmsg, &Error{err: "overflow packing opt"}
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}
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// Option code
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msg[off], msg[off+1] = packUint16(element.(EDNS0).Option())
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// Length
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msg[off+2], msg[off+3] = packUint16(uint16(len(b)))
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off += 4
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// Actual data
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copy(msg[off:off+len(b)], b)
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off += len(b)
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}
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case `dns:"a"`:
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// It must be a slice of 4, even if it is 16, we encode
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// only the first 4
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if off+net.IPv4len > lenmsg {
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return lenmsg, &Error{err: "overflow packing a"}
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}
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switch fv.Len() {
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case net.IPv6len:
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msg[off] = byte(fv.Index(12).Uint())
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msg[off+1] = byte(fv.Index(13).Uint())
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msg[off+2] = byte(fv.Index(14).Uint())
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msg[off+3] = byte(fv.Index(15).Uint())
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off += net.IPv4len
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case net.IPv4len:
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msg[off] = byte(fv.Index(0).Uint())
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msg[off+1] = byte(fv.Index(1).Uint())
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msg[off+2] = byte(fv.Index(2).Uint())
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msg[off+3] = byte(fv.Index(3).Uint())
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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 lenmsg, &Error{err: "overflow packing a"}
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}
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case `dns:"aaaa"`:
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if fv.Len() == 0 {
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break
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}
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if fv.Len() > net.IPv6len || off+fv.Len() > lenmsg {
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return lenmsg, &Error{err: "overflow packing aaaa"}
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}
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for j := 0; j < net.IPv6len; j++ {
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msg[off] = byte(fv.Index(j).Uint())
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off++
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}
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case `dns:"wks"`:
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if off == lenmsg {
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break // dyn. updates
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}
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if val.Field(i).Len() == 0 {
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break
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}
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var bitmapbyte uint16
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for j := 0; j < val.Field(i).Len(); j++ {
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serv := uint16((fv.Index(j).Uint()))
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bitmapbyte = uint16(serv / 8)
|
|
if int(bitmapbyte) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing wks"}
|
|
}
|
|
bit := uint16(serv) - bitmapbyte*8
|
|
msg[bitmapbyte] = byte(1 << (7 - bit))
|
|
}
|
|
off += int(bitmapbyte)
|
|
case `dns:"nsec"`: // NSEC/NSEC3
|
|
// This is the uint16 type bitmap
|
|
if val.Field(i).Len() == 0 {
|
|
// Do absolutely nothing
|
|
break
|
|
}
|
|
|
|
lastwindow := uint16(0)
|
|
length := uint16(0)
|
|
if off+2 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing nsecx"}
|
|
}
|
|
for j := 0; j < val.Field(i).Len(); j++ {
|
|
t := uint16((fv.Index(j).Uint()))
|
|
window := uint16(t / 256)
|
|
if lastwindow != window {
|
|
// New window, jump to the new offset
|
|
off += int(length) + 3
|
|
if off > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing nsecx bitmap"}
|
|
}
|
|
}
|
|
length = (t - window*256) / 8
|
|
bit := t - (window * 256) - (length * 8)
|
|
if off+2+int(length) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing nsecx bitmap"}
|
|
}
|
|
|
|
// Setting the window #
|
|
msg[off] = byte(window)
|
|
// Setting the octets length
|
|
msg[off+1] = byte(length + 1)
|
|
// Setting the bit value for the type in the right octet
|
|
msg[off+2+int(length)] |= byte(1 << (7 - bit))
|
|
lastwindow = window
|
|
}
|
|
off += 2 + int(length)
|
|
off++
|
|
if off > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing nsecx bitmap"}
|
|
}
|
|
}
|
|
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 val.Type().Field(i).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 val.Type().Field(i).Tag {
|
|
default:
|
|
return lenmsg, &Error{"bad tag packing string: " + val.Type().Field(i).Tag.Get("dns")}
|
|
case `dns:"base64"`:
|
|
b64, err := packBase64([]byte(s))
|
|
if err != nil {
|
|
return lenmsg, &Error{err: "overflow packing base64"}
|
|
}
|
|
copy(msg[off:off+len(b64)], b64)
|
|
off += len(b64)
|
|
case `dns:"domain-name"`:
|
|
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, err := packBase32([]byte(s))
|
|
if err != nil {
|
|
return lenmsg, &Error{err: "overflow packing base32"}
|
|
}
|
|
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, &Error{err: "overflow packing hex"}
|
|
}
|
|
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:"txt"`:
|
|
fallthrough
|
|
case "":
|
|
// Counted string: 1 byte length.
|
|
if len(s) > 255 || off+1+len(s) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow packing string"}
|
|
}
|
|
msg[off] = byte(len(s))
|
|
off++
|
|
for i := 0; i < len(s); i++ {
|
|
msg[off+i] = s[i]
|
|
}
|
|
off += len(s)
|
|
}
|
|
}
|
|
}
|
|
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
|
|
}
|
|
|
|
// TODO(mg): Fix use of rdlength here
|
|
|
|
// Unpack a reflect.StructValue from msg.
|
|
// Same restrictions as packStructValue.
|
|
func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, err error) {
|
|
var rdstart int
|
|
lenmsg := len(msg)
|
|
for i := 0; i < val.NumField(); i++ {
|
|
switch fv := val.Field(i); fv.Kind() {
|
|
default:
|
|
return lenmsg, &Error{err: "bad kind 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)
|
|
servers := make([]string, 0)
|
|
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"`:
|
|
txt := make([]string, 0)
|
|
rdlength := off + int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
Txts:
|
|
if off == lenmsg { // dyn. updates, no rdata is OK
|
|
break
|
|
}
|
|
l := int(msg[off])
|
|
if off+l+1 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking txt"}
|
|
}
|
|
txt = append(txt, string(msg[off+1:off+l+1]))
|
|
off += l + 1
|
|
if off < rdlength {
|
|
// More
|
|
goto Txts
|
|
}
|
|
fv.Set(reflect.ValueOf(txt))
|
|
case `dns:"opt"`: // edns0
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
endrr := off + rdlength
|
|
if rdlength == 0 {
|
|
// This is an EDNS0 (OPT Record) with no rdata
|
|
// We can safely return here.
|
|
break
|
|
}
|
|
edns := make([]EDNS0, 0)
|
|
Option:
|
|
code := uint16(0)
|
|
if off+2 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking opt"}
|
|
}
|
|
code, off = unpackUint16(msg, off)
|
|
optlen, off1 := unpackUint16(msg, off)
|
|
if off1+int(optlen) > off+rdlength {
|
|
return lenmsg, &Error{err: "overflow unpacking opt"}
|
|
}
|
|
switch code {
|
|
case EDNS0NSID:
|
|
e := new(EDNS0_NSID)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0SUBNET:
|
|
e := new(EDNS0_SUBNET)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0UL:
|
|
e := new(EDNS0_UL)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0LLQ:
|
|
e := new(EDNS0_LLQ)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0DAU:
|
|
e := new(EDNS0_DAU)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0DHU:
|
|
e := new(EDNS0_DHU)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
case EDNS0N3U:
|
|
e := new(EDNS0_N3U)
|
|
e.unpack(msg[off1 : off1+int(optlen)])
|
|
edns = append(edns, e)
|
|
off = off1 + int(optlen)
|
|
default:
|
|
// do nothing?
|
|
off = off1 + int(optlen)
|
|
}
|
|
if off < endrr {
|
|
goto Option
|
|
}
|
|
fv.Set(reflect.ValueOf(edns))
|
|
case `dns:"a"`:
|
|
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 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
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
endrr := rdstart + rdlength
|
|
serv := make([]uint16, 0)
|
|
j := 0
|
|
for off < endrr {
|
|
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 == lenmsg {
|
|
break
|
|
}
|
|
// Rest of the record is the type bitmap
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
endrr := rdstart + rdlength
|
|
if off+2 > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking nsecx"}
|
|
}
|
|
nsec := make([]uint16, 0)
|
|
length := 0
|
|
window := 0
|
|
for off+2 < endrr {
|
|
window = int(msg[off])
|
|
length = int(msg[off+1])
|
|
//println("off, windows, length, end", off, window, length, endrr)
|
|
if length == 0 {
|
|
// A length window of zero is strange. If there
|
|
// the window should not have been specified. Bail out
|
|
// println("dns: length == 0 when unpacking NSEC")
|
|
return lenmsg, ErrRdata
|
|
}
|
|
if length > 32 {
|
|
return lenmsg, ErrRdata
|
|
}
|
|
|
|
// Walk the bytes in the window - and check the bit settings...
|
|
off += 2
|
|
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
|
|
}
|
|
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" {
|
|
rdstart = off
|
|
}
|
|
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:
|
|
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:"hex"`:
|
|
// Rest of the RR is hex encoded, network order an issue here?
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
endrr := rdstart + rdlength
|
|
if endrr > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking hex"}
|
|
}
|
|
s = hex.EncodeToString(msg[off:endrr])
|
|
off = endrr
|
|
case `dns:"base64"`:
|
|
// Rest of the RR is base64 encoded value
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
endrr := rdstart + rdlength
|
|
if endrr > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking base64"}
|
|
}
|
|
s = unpackBase64(msg[off:endrr])
|
|
off = endrr
|
|
case `dns:"cdomain-name"`:
|
|
fallthrough
|
|
case `dns:"domain-name"`:
|
|
if off == lenmsg {
|
|
// zero rdata foo, OK for dyn. updates
|
|
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 = unpackBase32(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"`:
|
|
// 1 txt piece
|
|
rdlength := int(val.FieldByName("Hdr").FieldByName("Rdlength").Uint())
|
|
Txt:
|
|
if off >= lenmsg || off+1+int(msg[off]) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking txt"}
|
|
}
|
|
n := int(msg[off])
|
|
off++
|
|
for i := 0; i < n; i++ {
|
|
s += string(msg[off+i])
|
|
}
|
|
off += n
|
|
if off < rdlength {
|
|
// More to
|
|
goto Txt
|
|
}
|
|
case "":
|
|
if off >= lenmsg || off+1+int(msg[off]) > lenmsg {
|
|
return lenmsg, &Error{err: "overflow unpacking string"}
|
|
}
|
|
n := int(msg[off])
|
|
off++
|
|
for i := 0; i < n; i++ {
|
|
s += string(msg[off+i])
|
|
}
|
|
off += n
|
|
}
|
|
fv.SetString(s)
|
|
}
|
|
}
|
|
return off, nil
|
|
}
|
|
|
|
// Helper function for unpacking
|
|
func unpackUint16(msg []byte, off int) (v uint16, off1 int) {
|
|
v = uint16(msg[off])<<8 | uint16(msg[off+1])
|
|
off1 = off + 2
|
|
return
|
|
}
|
|
|
|
// UnpackStruct unpacks a binary message from offset off to the interface
|
|
// value given.
|
|
func UnpackStruct(any interface{}, msg []byte, off int) (off1 int, err error) {
|
|
off, err = unpackStructValue(structValue(any), msg, off)
|
|
return off, err
|
|
}
|
|
|
|
func unpackBase32(b []byte) string {
|
|
b32 := make([]byte, base32.HexEncoding.EncodedLen(len(b)))
|
|
base32.HexEncoding.Encode(b32, b)
|
|
return string(b32)
|
|
}
|
|
|
|
func unpackBase64(b []byte) string {
|
|
b64 := make([]byte, base64.StdEncoding.EncodedLen(len(b)))
|
|
base64.StdEncoding.Encode(b64, b)
|
|
return string(b64)
|
|
}
|
|
|
|
// Helper function for packing
|
|
func packUint16(i uint16) (byte, byte) {
|
|
return byte(i >> 8), byte(i)
|
|
}
|
|
|
|
func packBase64(s []byte) ([]byte, error) {
|
|
b64len := base64.StdEncoding.DecodedLen(len(s))
|
|
buf := make([]byte, b64len)
|
|
n, err := base64.StdEncoding.Decode(buf, []byte(s))
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
buf = buf[:n]
|
|
return buf, nil
|
|
}
|
|
|
|
// Helper function for packing, mostly used in dnssec.go
|
|
func packBase32(s []byte) ([]byte, error) {
|
|
b32len := base32.HexEncoding.DecodedLen(len(s))
|
|
buf := make([]byte, b32len)
|
|
n, err := base32.HexEncoding.Decode(buf, []byte(s))
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
buf = buf[:n]
|
|
return buf, nil
|
|
}
|
|
|
|
// Resource record packer, pack 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
|
|
}
|
|
rawSetRdlength(msg, off, off1)
|
|
return off1, nil
|
|
}
|
|
|
|
// Resource record unpacker, unpack 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 := rr_mk[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
|
|
}
|
|
|
|
// 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) {
|
|
var dh Header
|
|
var compression map[string]int
|
|
if dns.Compress {
|
|
compression = make(map[string]int) // Compression pointer mappings
|
|
} else {
|
|
compression = nil
|
|
}
|
|
|
|
// 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))
|
|
|
|
msg = make([]byte, dns.packLen()+1)
|
|
// 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)
|
|
|
|
// Arrays.
|
|
dns.Question = make([]Question, dh.Qdcount)
|
|
dns.Answer = make([]RR, dh.Ancount)
|
|
dns.Ns = make([]RR, dh.Nscount)
|
|
dns.Extra = make([]RR, dh.Arcount)
|
|
|
|
for i := 0; i < len(dns.Question); i++ {
|
|
off, err = UnpackStruct(&dns.Question[i], msg, off)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Answer); i++ {
|
|
dns.Answer[i], off, err = UnpackRR(msg, off)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Ns); i++ {
|
|
dns.Ns[i], off, err = UnpackRR(msg, off)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
dns.Extra[i], off, err = UnpackRR(msg, off)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
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))
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// 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
|
|
}
|
|
|
|
// packLen returns the message length when in UNcompressed wire format.
|
|
func (dns *Msg) packLen() int {
|
|
// Message header is always 12 bytes
|
|
l := 12
|
|
for i := 0; i < len(dns.Question); i++ {
|
|
l += dns.Question[i].len()
|
|
}
|
|
for i := 0; i < len(dns.Answer); i++ {
|
|
l += dns.Answer[i].len()
|
|
}
|
|
for i := 0; i < len(dns.Ns); i++ {
|
|
l += dns.Ns[i].len()
|
|
}
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
l += dns.Extra[i].len()
|
|
}
|
|
return l
|
|
}
|
|
|
|
// 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 {
|
|
// Message header is always 12 bytes
|
|
l := 12
|
|
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
|
|
} else {
|
|
compressionLenHelper(compression, dns.Answer[i].Header().Name)
|
|
}
|
|
l += 1 - compressionLenType(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
|
|
} else {
|
|
compressionLenHelper(compression, dns.Ns[i].Header().Name)
|
|
}
|
|
l += 1 - compressionLenType(compression, dns.Ns[i])
|
|
}
|
|
}
|
|
for i := 0; i < len(dns.Extra); i++ {
|
|
if dns.Compress {
|
|
k, ok := compressionLenSearch(compression, dns.Extra[i].Header().Name)
|
|
if ok {
|
|
l += 1 - k
|
|
} else {
|
|
compressionLenHelper(compression, dns.Extra[i].Header().Name)
|
|
}
|
|
l += 1 - compressionLenType(compression, dns.Extra[i])
|
|
}
|
|
}
|
|
return l
|
|
}
|
|
|
|
func (dns *Msg) copy() *Msg {
|
|
r1 := new(Msg)
|
|
r1.MsgHdr = dns.MsgHdr
|
|
r1.Compress = dns.Compress
|
|
r1.Question = make([]Question, len(dns.Question))
|
|
r1.Answer = make([]RR, len(dns.Answer))
|
|
r1.Ns = make([]RR, len(dns.Ns))
|
|
r1.Extra = make([]RR, len(dns.Extra))
|
|
copy(r1.Question, dns.Question)
|
|
copy(r1.Answer, dns.Answer)
|
|
copy(r1.Ns, dns.Ns)
|
|
copy(r1.Extra, dns.Extra)
|
|
return r1
|
|
}
|
|
|
|
// Put the parts of the name in the compression map.
|
|
func compressionLenHelper(c map[string]int, s string) {
|
|
pref := ""
|
|
lbs := SplitDomainName(s)
|
|
for j := len(lbs) - 1; j >= 0; j-- {
|
|
c[lbs[j]+"."+pref] = 1 + len(pref) + len(lbs[j])
|
|
pref = lbs[j] + "." + pref
|
|
}
|
|
}
|
|
|
|
// Look for each part in the compression map and returns its length
|
|
func compressionLenSearch(c map[string]int, s string) (int, bool) {
|
|
off := 0
|
|
end := false
|
|
for {
|
|
if end {
|
|
break
|
|
}
|
|
if _, ok := c[s[off:]]; ok {
|
|
return len(s[off:]), true
|
|
}
|
|
off, end = NextLabel(s, off)
|
|
}
|
|
// TODO(miek): not sure if need, leave this for later debugging
|
|
if _, ok := c[s[off:]]; ok {
|
|
return len(s[off:]), true
|
|
}
|
|
return 0, false
|
|
}
|
|
|
|
// Check the ownernames too of the types that have cdomain, do
|
|
// this manually to avoid reflection.
|
|
func compressionLenType(c map[string]int, r RR) int {
|
|
switch x := r.(type) {
|
|
case *NS:
|
|
k, ok := compressionLenSearch(c, x.Ns)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Ns)
|
|
}
|
|
case *MX:
|
|
k, ok := compressionLenSearch(c, x.Mx)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mx)
|
|
}
|
|
case *CNAME:
|
|
k, ok := compressionLenSearch(c, x.Target)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Target)
|
|
}
|
|
case *PTR:
|
|
k, ok := compressionLenSearch(c, x.Ptr)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Ptr)
|
|
}
|
|
case *SOA:
|
|
k, ok := compressionLenSearch(c, x.Ns)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Ns)
|
|
}
|
|
k, ok = compressionLenSearch(c, x.Mbox)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mbox)
|
|
}
|
|
case *MB:
|
|
k, ok := compressionLenSearch(c, x.Mb)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mb)
|
|
}
|
|
case *MG:
|
|
k, ok := compressionLenSearch(c, x.Mg)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mg)
|
|
}
|
|
case *MR:
|
|
k, ok := compressionLenSearch(c, x.Mr)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mr)
|
|
}
|
|
case *MF:
|
|
k, ok := compressionLenSearch(c, x.Mf)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Mf)
|
|
}
|
|
case *MD:
|
|
k, ok := compressionLenSearch(c, x.Md)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Md)
|
|
}
|
|
case *RT:
|
|
k, ok := compressionLenSearch(c, x.Host)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Host)
|
|
}
|
|
case *MINFO:
|
|
k, ok := compressionLenSearch(c, x.Rmail)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Rmail)
|
|
}
|
|
k, ok = compressionLenSearch(c, x.Email)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Email)
|
|
}
|
|
case *AFSDB:
|
|
k, ok := compressionLenSearch(c, x.Hostname)
|
|
if ok {
|
|
return k
|
|
} else {
|
|
compressionLenHelper(c, x.Hostname)
|
|
}
|
|
}
|
|
return 1 // noop when nothing is found
|
|
}
|
|
|
|
// Id return 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())
|
|
}
|