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36 lines
1.2 KiB
Go
36 lines
1.2 KiB
Go
// Package upstream abstracts a upstream lookups so that plugins can handle them in an unified way.
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package upstream
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import (
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"context"
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"fmt"
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"github.com/coredns/coredns/core/dnsserver"
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"github.com/coredns/coredns/plugin/pkg/nonwriter"
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"github.com/coredns/coredns/request"
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"github.com/miekg/dns"
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)
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// Upstream is used to resolve CNAME or other external targets via CoreDNS itself.
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type Upstream struct{}
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// New creates a new Upstream to resolve names using the coredns process.
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func New() *Upstream { return &Upstream{} }
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// Lookup routes lookups to our selves to make it follow the plugin chain *again*, but with a (possibly) new query. As
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// we are doing the query against ourselves again, there is no actual new hop, as such RFC 6891 does not apply and we
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// need the EDNS0 option present in the *original* query to be present here too.
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func (u *Upstream) Lookup(ctx context.Context, state request.Request, name string, typ uint16) (*dns.Msg, error) {
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server, ok := ctx.Value(dnsserver.Key{}).(*dnsserver.Server)
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if !ok {
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return nil, fmt.Errorf("no full server is running")
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}
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req := state.NewWithQuestion(name, typ)
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nw := nonwriter.New(state.W)
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server.ServeDNS(ctx, nw, req.Req)
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return nw.Msg, nil
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}
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