d1f17fa7e0
Move all (almost all) Go files in middleware into their own packages. This makes for better naming and discoverability. Lot of changes elsewhere to make this change. The middleware.State was renamed to request.Request which is better, but still does not cover all use-cases. It was also moved out middleware because it is used by `dnsserver` as well. A pkg/dnsutil packages was added for shared, handy, dns util functions. All normalize functions are now put in normalize.go
85 lines
2 KiB
Go
85 lines
2 KiB
Go
package etcd
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import (
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"errors"
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"log"
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"github.com/miekg/coredns/request"
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"github.com/miekg/dns"
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"golang.org/x/net/context"
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)
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// Stub wraps an Etcd. We have this type so that it can have a ServeDNS method.
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type Stub struct {
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*Etcd
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Zone string // for what zone (and thus what nameservers are we called)
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}
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func (s Stub) ServeDNS(ctx context.Context, w dns.ResponseWriter, req *dns.Msg) (int, error) {
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if hasStubEdns0(req) {
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log.Printf("[WARNING] Forwarding cycle detected, refusing msg: %s", req.Question[0].Name)
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return dns.RcodeRefused, errors.New("stub forward cycle")
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}
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req = addStubEdns0(req)
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proxy, ok := (*s.Etcd.Stubmap)[s.Zone]
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if !ok { // somebody made a mistake..
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return dns.RcodeServerFailure, nil
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}
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state := request.Request{W: w, Req: req}
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m, e := proxy.Forward(state)
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if e != nil {
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return dns.RcodeServerFailure, e
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}
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m.RecursionAvailable, m.Compress = true, true
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state.SizeAndDo(m)
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w.WriteMsg(m)
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return dns.RcodeSuccess, nil
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}
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// hasStubEdns0 checks if the message is carrying our special edns0 zero option.
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func hasStubEdns0(m *dns.Msg) bool {
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option := m.IsEdns0()
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if option == nil {
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return false
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}
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for _, o := range option.Option {
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if o.Option() == ednsStubCode && len(o.(*dns.EDNS0_LOCAL).Data) == 1 &&
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o.(*dns.EDNS0_LOCAL).Data[0] == 1 {
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return true
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}
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}
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return false
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}
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// addStubEdns0 adds our special option to the message's OPT record.
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func addStubEdns0(m *dns.Msg) *dns.Msg {
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option := m.IsEdns0()
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// Add a custom EDNS0 option to the packet, so we can detect loops when 2 stubs are forwarding to each other.
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if option != nil {
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option.Option = append(option.Option, &dns.EDNS0_LOCAL{Code: ednsStubCode, Data: []byte{1}})
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return m
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}
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m.Extra = append(m.Extra, ednsStub)
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return m
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}
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const (
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ednsStubCode = dns.EDNS0LOCALSTART + 10
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stubDomain = "stub.dns"
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)
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var ednsStub = func() *dns.OPT {
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o := new(dns.OPT)
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o.Hdr.Name = "."
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o.Hdr.Rrtype = dns.TypeOPT
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o.SetUDPSize(4096)
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e := new(dns.EDNS0_LOCAL)
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e.Code = ednsStubCode
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e.Data = []byte{1}
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o.Option = append(o.Option, e)
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return o
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}()
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