func (cq *Cq) clientLookup(cr *clientRequest) {
// Ensure that this query makes some sense
if len(cr.Query.Questions) == 1 {
q := cr.Query.Questions[0]
c := make(chan *lookupRes)
go cq.collapsedLookup(q, c)
lres := <-c
l.Debug("final lookup reply -> %v", lres)
if lres != nil { // fixme: error
cres := lres.cres
p := &packet.ParsedPacket{}
p.Header.Id = cr.Query.Header.Id
p.Header.Response = true
p.Header.ResponseCode = cres.ResponseCode
p.Questions = cr.Query.Questions
if lres.negative {
p.Nameservers = append(p.Nameservers, cres.ResourceRecord...)
} else {
p.Answers = append(p.Answers, cres.ResourceRecord...)
}
cq.conn.WriteToUDP(packet.Assemble(p), cr.RemoteAddr)
} else {
l.Info("Lookup returned an error, should send it back to client (fixme): %+v", lres)
}
} else {
l.Info("Dropping nonsense query")
}
}
func (cq *Cq) advanceCache(q packet.QuestionFormat) *packet.ParsedPacket {
// our hardcoded, not so redundant slist
targetNS := "192.5.5.241:53"
targetXH := &packet.Namelabel{}
targetQT := q.Type
POP_LOOP:
for i := 0; ; i++ {
label := q.Name.PoppedLabel(i) // removes 'i' labels from the label list
nsrec, _ := cq.cache.Lookup(*label, constants.TYPE_NS)
if nsrec != nil { // we got an NS cache entry for this level
var candidate_cres *cache.CacheResult
var candidate_label packet.Namelabel
// loop trough all NS servers for this record
for _, candidate_data := range nsrec.ResourceRecord {
name, err := packet.ParseName(candidate_data.Data)
if err == nil {
l.Debug("NS %v handles %v", name, label)
cres, _ := cq.cache.Lookup(name, constants.TYPE_A)
if cres != nil {
candidate_cres = cres
} else {
candidate_label = name
}
}
}
// Fixme: We should try to resolve (yet unknown) nameservers
// even if we got a candidate_res as the one we are contacting
// might fail for some reason.
if candidate_cres == nil && candidate_label.Len() > 0 {
l.Debug("Looking up IP of known candidate: %v", candidate_label)
c := make(chan *lookupRes)
go cq.collapsedLookup(packet.QuestionFormat{Type: constants.TYPE_A, Class: constants.CLASS_IN, Name: candidate_label}, c)
lres := <-c
if lres != nil && lres.negative == false {
candidate_cres = lres.cres
}
}
if candidate_cres != nil {
l.Debug("We got an RR: %v", candidate_cres)
for _, v := range candidate_cres.ResourceRecord {
if v.Type != constants.TYPE_A {
l.Panic("Not an A type: %v", v)
}
targetNS = fmt.Sprintf("%d.%d.%d.%d:53", v.Data[0], v.Data[1], v.Data[2], v.Data[3])
targetXH = label
break POP_LOOP
}
}
}
if label.Len() == 1 {
break
}
}
pp := &packet.ParsedPacket{}
pp.Header.Id = uint16(rand.Uint32()) // will simply overflow
pp.Header.Opcode = constants.OP_QUERY
pp.Header.QuestionCount = 1
pp.Questions = []packet.QuestionFormat{{Name: q.Name, Class: constants.CLASS_IN, Type: targetQT}}
remoteNs, err := net.ResolveUDPAddr("udp", targetNS)
if err == nil {
l.Info("+ op=query, remote=%s, type=%d, id=%d, name=%v", targetNS, targetQT, pp.Header.Id, q.Name)
cq.conn.WriteToUDP(packet.Assemble(pp), remoteNs)
cq.sq.registerQuery(pp.Questions[0], remoteNs, targetXH)
}
return pp
}