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https://github.com/coredns/coredns.git
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5b844b5017
* plugin/forward: add it This moves coredns/forward into CoreDNS. Fixes as a few bugs, adds a policy option and more tests to the plugin. Update the documentation, test IPv6 address and add persistent tests. * Always use random policy when spraying * include scrub fix here as well * use correct var name * Code review * go vet * Move logging to metrcs * Small readme updates * Fix readme
68 lines
1.3 KiB
Go
68 lines
1.3 KiB
Go
package forward
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import (
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"log"
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"sync/atomic"
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"github.com/miekg/dns"
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)
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// For HC we send to . IN NS +norec message to the upstream. Dial timeouts and empty
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// replies are considered fails, basically anything else constitutes a healthy upstream.
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func (h *host) Check() {
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h.Lock()
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if h.checking {
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h.Unlock()
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return
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}
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h.checking = true
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h.Unlock()
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err := h.send()
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if err != nil {
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log.Printf("[INFO] healtheck of %s failed with %s", h.addr, err)
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HealthcheckFailureCount.WithLabelValues(h.addr).Add(1)
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atomic.AddUint32(&h.fails, 1)
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} else {
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atomic.StoreUint32(&h.fails, 0)
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}
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h.Lock()
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h.checking = false
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h.Unlock()
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return
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}
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func (h *host) send() error {
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hcping := new(dns.Msg)
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hcping.SetQuestion(".", dns.TypeNS)
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hcping.RecursionDesired = false
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m, _, err := h.client.Exchange(hcping, h.addr)
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// If we got a header, we're alright, basically only care about I/O errors 'n stuff
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if err != nil && m != nil {
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// Silly check, something sane came back
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if m.Response || m.Opcode == dns.OpcodeQuery {
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err = nil
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}
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}
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return err
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}
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// down returns true is this host has more than maxfails fails.
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func (h *host) down(maxfails uint32) bool {
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if maxfails == 0 {
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return false
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}
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fails := atomic.LoadUint32(&h.fails)
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return fails > maxfails
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}
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