47 lines
1.3 KiB
Go
47 lines
1.3 KiB
Go
// The example plugin prints example to stdout on every packet received.
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package example
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import (
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"fmt"
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"io"
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"os"
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"github.com/coredns/coredns/plugin"
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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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// Example is an example plugin to show how to write a plugin.
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type Example struct {
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Next plugin.Handler
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}
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// ServeDNS implements the plugin.Handler interface.
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func (e Example) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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// Somewhat convoluted, as we could have printed "example" here and just call
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// the next plugin - but as an example, show how to wrap a ResponseWriter might be
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// educational.
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pw := NewResponsePrinter(w)
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return plugin.NextOrFailure(e.Name(), e.Next, ctx, pw, r)
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}
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// Name implements the Handler interface.
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func (e Example) Name() string { return "example" }
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type ResponsePrinter struct {
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dns.ResponseWriter
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}
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// NewResponsePrinter returns a dns.Msg modifier that print example when a query is received.
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func NewResponsePrinter(w dns.ResponseWriter) *ResponsePrinter {
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return &ResponsePrinter{ResponseWriter: w}
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}
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// WriteMsg records the status code and calls the underlying ResponseWriter's WriteMsg method.
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func (r *ResponsePrinter) WriteMsg(res *dns.Msg) error {
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fmt.Fprintf(out, "example")
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return r.ResponseWriter.WriteMsg(res)
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}
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var out io.Writer = os.Stdout
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