53 lines
1.3 KiB
Go
53 lines
1.3 KiB
Go
// Package nsid implements NSID protocol
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package nsid
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import (
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"context"
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"encoding/hex"
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"github.com/coredns/coredns/plugin"
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"github.com/miekg/dns"
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)
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// Nsid plugin
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type Nsid struct {
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Next plugin.Handler
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Data string
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}
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// ResponseWriter is a response writer that adds NSID response
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type ResponseWriter struct {
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dns.ResponseWriter
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Data string
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}
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// ServeDNS implements the plugin.Handler interface.
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func (n Nsid) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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if option := r.IsEdns0(); option != nil {
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for _, o := range option.Option {
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if _, ok := o.(*dns.EDNS0_NSID); ok {
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nw := &ResponseWriter{ResponseWriter: w, Data: n.Data}
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return plugin.NextOrFailure(n.Name(), n.Next, ctx, nw, r)
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}
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}
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}
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return plugin.NextOrFailure(n.Name(), n.Next, ctx, w, r)
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}
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// WriteMsg implements the dns.ResponseWriter interface.
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func (w *ResponseWriter) WriteMsg(res *dns.Msg) error {
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if option := res.IsEdns0(); option != nil {
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for _, o := range option.Option {
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if e, ok := o.(*dns.EDNS0_NSID); ok {
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e.Code = dns.EDNS0NSID
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e.Nsid = hex.EncodeToString([]byte(w.Data))
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}
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}
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}
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returned := w.ResponseWriter.WriteMsg(res)
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return returned
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}
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// Name implements the Handler interface.
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func (n Nsid) Name() string { return "nsid" }
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