// Lookup returns the CacheResult of given Namelabel and Type combination
// rr will be nil if there was no positive match
// re will be nil if there was no negative match
// rr == re == nil if the entry is completely unknown
func (c *Cache) Lookup(label packet.Namelabel, t uint16) (rr *CacheResult, re *CacheResult) {
key := label.ToKey()
now := time.Now()
c.Lock()
defer c.Unlock()
if c.CacheMap[key] != nil {
qtypes := []uint16{t} // the types we are going to query from the cache
ent := make([]packet.ResourceRecordFormat, 0) // the final response
if t == constants.QTYPE_ALL && len(c.CacheMap[key]) > 0 {
// special case: This was an ANY query and we DO have some data.
// As QTYPE_ALL is not a valid type, we are just going to return all rr's we got data for
qtypes = []uint16{}
for k, _ := range c.CacheMap[key] {
qtypes = append(qtypes, k)
}
}
for _, qtype := range qtypes {
if c.CacheMap[key][qtype] != nil {
for _, item := range c.CacheMap[key][qtype] {
if now.Before(item.deadline) {
ttl := uint32(item.deadline.Sub(now).Seconds())
ent = append(ent, packet.ResourceRecordFormat{Name: label, Class: constants.CLASS_IN, Type: qtype, Ttl: ttl, Data: item.data})
}
}
}
}
if len(ent) > 0 { // ensure to return a null pointer if ent is empty
rr = &CacheResult{ResourceRecord: ent, ResponseCode: constants.RC_NO_ERR}
}
}
// rr will be nil on cache miss, check if we have a negative cache entry
if rr == nil && c.MissMap[key] != nil {
mtype := t
if c.MissMap[key][constants.TYPE_SOA] != nil {
// we do have a negative soa entry, so the domain simply does not exist
// and there is no point in looking up 't'
mtype = constants.TYPE_SOA
}
if c.MissMap[key][mtype] != nil {
for _, item := range c.MissMap[key][mtype] {
if now.Before(item.deadline) {
ttl := uint32(item.deadline.Sub(now).Seconds())
// unparse fiddled-in soa label
rend := item.data[0] + 1
rlabel := item.data[1:rend]
plabel, _ := packet.ParseName(rlabel)
ent := make([]packet.ResourceRecordFormat, 0)
ent = append(ent, packet.ResourceRecordFormat{Name: plabel, Class: constants.CLASS_IN, Type: constants.TYPE_SOA, Ttl: ttl, Data: item.data[rend:]})
re = &CacheResult{ResourceRecord: ent, ResponseCode: item.rcode}
}
}
}
}
return
}
