10db2a80df
* Add middleware/cache Add a caching middleware that caches nxdomain, nodata and successful responses. It differentiates between DNSSEC on normal DNS replies. Each reply is compress and scrubbed so it will fit the specific client asking for it. * first simple test, less exporting of stuff * more * Add middleware/cache Add a caching middleware that caches nxdomain, nodata and successful responses. It differentiates between DNSSEC on normal DNS replies. Each reply is compressed and scrubbed so it will fit the specific client asking for it. The TTL is decremented with the time spend in the cache. There is syntax that allows you to cap the TTL for all records, no matter what. This allows for a shortlived cache, just to absorb query peaks. +Tests * cache test infrastructure * Testing
98 lines
2.1 KiB
Go
98 lines
2.1 KiB
Go
package cache
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import (
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"strconv"
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"time"
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"github.com/miekg/dns"
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)
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type item struct {
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Authoritative bool
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AuthenticatedData bool
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RecursionAvailable bool
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Answer []dns.RR
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Ns []dns.RR
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Extra []dns.RR
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origTtl uint32
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stored time.Time
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}
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func newItem(m *dns.Msg, d time.Duration) *item {
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i := new(item)
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i.Authoritative = m.Authoritative
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i.AuthenticatedData = m.AuthenticatedData
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i.RecursionAvailable = m.RecursionAvailable
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i.Answer = m.Answer
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i.Ns = m.Ns
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i.Extra = make([]dns.RR, len(m.Extra))
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// Don't copy OPT record as these are hop-by-hop.
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j := 0
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for _, e := range m.Extra {
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if e.Header().Rrtype == dns.TypeOPT {
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continue
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}
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i.Extra[j] = e
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j++
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}
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i.Extra = i.Extra[:j]
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i.origTtl = uint32(d.Seconds())
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i.stored = time.Now().UTC()
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return i
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}
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// toMsg turns i into a message, it tailers to reply to m.
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func (i *item) toMsg(m *dns.Msg) *dns.Msg {
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m1 := new(dns.Msg)
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m1.SetReply(m)
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m1.Authoritative = i.Authoritative
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m1.AuthenticatedData = i.AuthenticatedData
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m1.RecursionAvailable = i.RecursionAvailable
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m1.Compress = true
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m1.Answer = i.Answer
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m1.Ns = i.Ns
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m1.Extra = i.Extra
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ttl := int(i.origTtl) - int(time.Now().UTC().Sub(i.stored).Seconds())
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if ttl < baseTtl {
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ttl = baseTtl
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}
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setCap(m1, uint32(ttl))
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return m1
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}
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// setCap sets the ttl on all RRs in all sections.
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func setCap(m *dns.Msg, ttl uint32) {
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for _, r := range m.Answer {
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r.Header().Ttl = uint32(ttl)
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}
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for _, r := range m.Ns {
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r.Header().Ttl = uint32(ttl)
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}
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for _, r := range m.Extra {
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r.Header().Ttl = uint32(ttl)
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}
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}
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// nodataKey returns a caching key for NODATA responses.
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func noDataKey(qname string, qtype uint16, do bool) string {
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if do {
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return "1" + qname + ".." + strconv.Itoa(int(qtype))
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}
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return "0" + qname + ".." + strconv.Itoa(int(qtype))
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}
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// nameErrorKey returns a caching key for NXDOMAIN responses.
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func nameErrorKey(qname string, do bool) string {
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if do {
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return "1" + qname
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}
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return "0" + qname
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}
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// successKey returns a caching key for successfull answers.
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func successKey(qname string, qtype uint16, do bool) string { return noDataKey(qname, qtype, do) }
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