55 lines
1.2 KiB
Go
55 lines
1.2 KiB
Go
package upstream
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import (
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"github.com/coredns/coredns/plugin"
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"github.com/miekg/dns"
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"github.com/pkg/errors"
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"golang.org/x/net/context"
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"time"
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)
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const (
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defaultTimeout = 5 * time.Second
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)
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// Upstream is a simplified interface for proxy destination
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type Upstream interface {
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Exchange(ctx context.Context, query *dns.Msg) (*dns.Msg, error)
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Close() error
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}
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// UpstreamPlugin is a simplified DNS proxy using a generic upstream interface
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type UpstreamPlugin struct {
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Upstreams []Upstream
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Next plugin.Handler
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}
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// Initialize the upstream plugin
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func New() *UpstreamPlugin {
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p := &UpstreamPlugin{
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Upstreams: []Upstream{},
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}
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return p
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}
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// ServeDNS implements interface for CoreDNS plugin
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func (p *UpstreamPlugin) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
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var reply *dns.Msg
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var backendErr error
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for i := range p.Upstreams {
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upstream := p.Upstreams[i]
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reply, backendErr = upstream.Exchange(ctx, r)
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if backendErr == nil {
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w.WriteMsg(reply)
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return 0, nil
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}
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}
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return dns.RcodeServerFailure, errors.Wrap(backendErr, "failed to contact any of the upstreams")
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}
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// Name implements interface for CoreDNS plugin
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func (p *UpstreamPlugin) Name() string { return "upstream" }
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