c08497adee
Did a `misspell . | grep -v ^vendor` and fixed several typos. Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
78 lines
2.7 KiB
Go
78 lines
2.7 KiB
Go
package kubernetes
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import "github.com/miekg/dns"
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// AutoPathWriter implements a ResponseWriter that also does the following:
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// * reverts question section of a packet to its original state.
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// This is done to avoid the 'Question section mismatch:' error in client.
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// * Defers write to the client if the response code is NXDOMAIN. This is needed
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// to enable further search path probing if a search was not successful.
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// * Allow forced write to client regardless of response code. This is needed to
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// write the packet to the client if the final search in the path fails to
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// produce results.
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// * Overwrites response code with AutoPathWriter.Rcode if the response code
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// is NXDOMAIN (NameError). This is needed to support the AutoPath.OnNXDOMAIN
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// function, which returns a NOERROR to client instead of NXDOMAIN if the final
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// search in the path fails to produce results.
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type AutoPathWriter struct {
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dns.ResponseWriter
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original dns.Question
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Rcode int
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Sent bool
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}
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// NewAutoPathWriter returns a pointer to a new AutoPathWriter
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func NewAutoPathWriter(w dns.ResponseWriter, r *dns.Msg) *AutoPathWriter {
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return &AutoPathWriter{
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ResponseWriter: w,
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original: r.Question[0],
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Rcode: dns.RcodeSuccess,
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}
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}
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// WriteMsg writes to client, unless response will be NXDOMAIN
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func (apw *AutoPathWriter) WriteMsg(res *dns.Msg) error {
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return apw.overrideMsg(res, false)
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}
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// ForceWriteMsg forces the write to client regardless of response code
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func (apw *AutoPathWriter) ForceWriteMsg(res *dns.Msg) error {
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return apw.overrideMsg(res, true)
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}
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// overrideMsg overrides rcode, reverts question, adds CNAME, and calls the
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// underlying ResponseWriter's WriteMsg method unless the write is deferred,
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// or force = true.
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func (apw *AutoPathWriter) overrideMsg(res *dns.Msg, force bool) error {
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if res.Rcode == dns.RcodeNameError {
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res.Rcode = apw.Rcode
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}
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if res.Rcode != dns.RcodeSuccess && !force {
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return nil
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}
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for _, a := range res.Answer {
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if apw.original.Name == a.Header().Name {
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continue
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}
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res.Answer = append(res.Answer, nil)
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copy(res.Answer[1:], res.Answer)
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res.Answer[0] = newCNAME(apw.original.Name, dns.Fqdn(a.Header().Name), a.Header().Ttl)
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}
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res.Question[0] = apw.original
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apw.Sent = true
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return apw.ResponseWriter.WriteMsg(res)
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}
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// Write is a wrapper that records the size of the message that gets written.
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func (apw *AutoPathWriter) Write(buf []byte) (int, error) {
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n, err := apw.ResponseWriter.Write(buf)
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return n, err
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}
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// Hijack implements dns.Hijacker. It simply wraps the underlying
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// ResponseWriter's Hijack method if there is one, or returns an error.
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func (apw *AutoPathWriter) Hijack() {
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apw.ResponseWriter.Hijack()
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return
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}
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