268 lines
6.6 KiB
Go
268 lines
6.6 KiB
Go
package dns
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// Everything is assumed in the ClassINET class. If
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// you need other classes you are on your own.
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// SetReply creates a reply packet from a request message.
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func (dns *Msg) SetReply(request *Msg) {
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dns.MsgHdr.Id = request.MsgHdr.Id
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dns.MsgHdr.Authoritative = true
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dns.MsgHdr.Response = true
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dns.MsgHdr.Opcode = OpcodeQuery
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dns.MsgHdr.Rcode = RcodeSuccess
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dns.Question = make([]Question, 1)
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dns.Question[0] = request.Question[0]
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}
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// SetQuestion creates a question packet.
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func (dns *Msg) SetQuestion(z string, t uint16) {
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dns.MsgHdr.Id = Id()
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dns.MsgHdr.RecursionDesired = true
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dns.Question = make([]Question, 1)
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dns.Question[0] = Question{z, t, ClassINET}
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}
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// SetNotify creates a notify packet.
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func (dns *Msg) SetNotify(z string) {
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dns.MsgHdr.Opcode = OpcodeNotify
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dns.MsgHdr.Authoritative = true
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dns.MsgHdr.Id = Id()
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dns.Question = make([]Question, 1)
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dns.Question[0] = Question{z, TypeSOA, ClassINET}
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}
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// SetRcode creates an error packet.
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func (dns *Msg) SetRcode(request *Msg, rcode int) {
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dns.MsgHdr.Rcode = rcode
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dns.MsgHdr.Opcode = OpcodeQuery
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dns.MsgHdr.Response = true
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dns.MsgHdr.Authoritative = false
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dns.MsgHdr.Id = request.MsgHdr.Id
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dns.Question = make([]Question, 1)
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dns.Question[0] = request.Question[0]
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}
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// SetRcodeFormatError creates a packet with FormError set.
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func (dns *Msg) SetRcodeFormatError(request *Msg) {
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dns.MsgHdr.Rcode = RcodeFormatError
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dns.MsgHdr.Opcode = OpcodeQuery
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dns.MsgHdr.Response = true
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dns.MsgHdr.Authoritative = false
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dns.MsgHdr.Id = request.MsgHdr.Id
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}
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// SetUpdate makes the message a dynamic update packet. It
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// sets the ZONE section to: z, TypeSOA, classINET.
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func (dns *Msg) SetUpdate(z string) {
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dns.MsgHdr.Id = Id()
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dns.MsgHdr.Opcode = OpcodeUpdate
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dns.Question = make([]Question, 1)
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dns.Question[0] = Question{z, TypeSOA, ClassINET}
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}
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// SetIxfr creates dns msg suitable for requesting an ixfr.
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func (dns *Msg) SetIxfr(z string, serial uint32) {
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dns.MsgHdr.Id = Id()
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dns.Question = make([]Question, 1)
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dns.Ns = make([]RR, 1)
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s := new(RR_SOA)
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s.Hdr = RR_Header{z, TypeSOA, ClassINET, DefaultTTL, 0}
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s.Serial = serial
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dns.Question[0] = Question{z, TypeIXFR, ClassINET}
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dns.Ns[0] = s
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}
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// SetAxfr creates dns msg suitable for requesting an axfr.
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func (dns *Msg) SetAxfr(z string) {
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dns.MsgHdr.Id = Id()
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dns.Question = make([]Question, 1)
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dns.Question[0] = Question{z, TypeAXFR, ClassINET}
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}
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// SetTsig appends a TSIG RR to the message.
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// This is only a skeleton Tsig RR that is added as the last RR in the
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// additional section. The caller should then call TsigGenerate,
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// to generate the complete TSIG with the secret.
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func (dns *Msg) SetTsig(z, algo string, fudge uint16, timesigned uint64) {
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t := new(RR_TSIG)
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t.Hdr = RR_Header{z, TypeTSIG, ClassANY, 0, 0}
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t.Algorithm = algo
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t.Fudge = 300
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t.TimeSigned = timesigned
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dns.Extra = append(dns.Extra, t)
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}
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// SetEdns0 appends a EDNS0 OPT RR to the message.
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// TSIG should always the last RR in a message.
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func (dns *Msg) SetEdns0(udpsize uint16, do bool) {
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e := new(RR_OPT)
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e.Hdr.Name = "."
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e.Hdr.Rrtype = TypeOPT
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e.SetUDPSize(udpsize)
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if do {
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e.SetDo()
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}
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dns.Extra = append(dns.Extra, e)
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}
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// IsRcode checks if the header of the packet has rcode set.
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func (dns *Msg) IsRcode(rcode int) (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Rcode == rcode
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return
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}
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// IsQuestion returns true if the packet is a question.
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func (dns *Msg) IsQuestion() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Response == false
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return
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}
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// IsRcodeFormatError checks if the message has FormErr set.
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func (dns *Msg) IsRcodeFormatError() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Rcode == RcodeFormatError
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return
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}
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// IsUpdate checks if the message is a dynamic update packet.
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func (dns *Msg) IsUpdate() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Opcode == OpcodeUpdate
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ok = ok && dns.Question[0].Qtype == TypeSOA
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return
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}
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// IsNotify checks if the message is a valid notify packet.
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func (dns *Msg) IsNotify() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Opcode == OpcodeNotify
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ok = ok && dns.Question[0].Qclass == ClassINET
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ok = ok && dns.Question[0].Qtype == TypeSOA
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return
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}
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// IsAxfr checks if the message is a valid axfr request packet.
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func (dns *Msg) IsAxfr() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Opcode == OpcodeQuery
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ok = ok && dns.Question[0].Qclass == ClassINET
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ok = ok && dns.Question[0].Qtype == TypeAXFR
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return
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}
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// IsIXfr checks if the message is a valid ixfr request packet.
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func (dns *Msg) IsIxfr() (ok bool) {
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if len(dns.Question) == 0 {
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return false
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}
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ok = dns.MsgHdr.Opcode == OpcodeQuery
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ok = ok && dns.Question[0].Qclass == ClassINET
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ok = ok && dns.Question[0].Qtype == TypeIXFR
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return
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}
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// IsTsig checks if the message has a TSIG record as the last record
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// in the additional section.
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func (dns *Msg) IsTsig() (ok bool) {
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if len(dns.Extra) > 0 {
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return dns.Extra[len(dns.Extra)-1].Header().Rrtype == TypeTSIG
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}
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return
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}
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// IsEdns0 checks if the message has a Edns0 record, any EDNS0
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// record in the additional section will do
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func (dns *Msg) IsEdns0() (ok bool) {
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for _, r := range dns.Extra {
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if r.Header().Rrtype == TypeOPT {
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return true
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}
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}
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return
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}
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// IsDomainName checks if s is a valid domainname.
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func IsDomainName(s string) bool { // copied from net package.
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// See RFC 1035, RFC 3696.
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if len(s) == 0 {
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return false
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}
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if len(s) > 255 {
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return false
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}
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if s[len(s)-1] != '.' { // simplify checking loop: make name end in dot
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s += "."
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}
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last := byte('.')
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ok := false // ok once we've seen a letter
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partlen := 0
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for i := 0; i < len(s); i++ {
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c := s[i]
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switch {
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default:
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return false
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case 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || c == '_' || c == '*':
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ok = true
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partlen++
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case '0' <= c && c <= '9':
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// fine
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partlen++
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case c == '-':
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// byte before dash cannot be dot
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if last == '.' {
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return false
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}
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partlen++
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case c == '.':
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// byte before dot cannot be dot, dash
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if last == '.' || last == '-' {
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return false
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}
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if partlen > 63 || partlen == 0 {
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return false
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}
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partlen = 0
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}
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last = c
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}
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return ok
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}
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// Return the number of labels in a domain name.
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// Need to add these kind of function in a structured way. TODO(mg)
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func Labels(a string) (c uint8) {
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// walk the string and count the dots
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// except when it is escaped
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esc := false
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for _, v := range a {
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switch v {
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case '.':
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if esc {
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esc = !esc
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continue
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}
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c++
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case '\\':
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esc = true
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}
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}
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return
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}
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