middleware/rewrite/reverter.go


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package rewrite

import "github.com/miekg/dns"

// ResponseReverter reverses the operations done on the question section of a packet.
// This is need because the client will otherwise disregards the response, i.e.
// dig will complain with ';; Question section mismatch: got miek.nl/HINFO/IN'
type ResponseReverter struct {
	dns.ResponseWriter
	original dns.Question
}

// NewResponseReverter returns a pointer to a new ResponseReverter.
func NewResponseReverter(w dns.ResponseWriter, r *dns.Msg) *ResponseReverter {
	return &ResponseReverter{
		ResponseWriter: w,
		original:       r.Question[0],
	}
}

// WriteMsg records the status code and calls the
// underlying ResponseWriter's WriteMsg method.
func (r *ResponseReverter) WriteMsg(res *dns.Msg) error {
	res.Question[0] = r.original
	return r.ResponseWriter.WriteMsg(res)
}

// Write is a wrapper that records the size of the message that gets written.
func (r *ResponseReverter) Write(buf []byte) (int, error) {
	n, err := r.ResponseWriter.Write(buf)
	return n, err
}

// Hijack implements dns.Hijacker. It simply wraps the underlying
// ResponseWriter's Hijack method if there is one, or returns an error.
func (r *ResponseReverter) Hijack() {
	r.ResponseWriter.Hijack()
	return
}