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plugin/forward: add HealthChecker interface (#1950)

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* plugin/forward: add HealthChecker interface

Make the HealthChecker interface and morph the current DNS health
checker into that interface.

Remove all whole bunch of method on Forward that didn't make sense.

This is done in preparation of adding a DoH client to forward - which
requires a completely different healthcheck implementation (and more,
but lets start here)

Signed-off-by: Miek Gieben <miek@miek.nl>

* Use protocol

Signed-off-by: Miek Gieben <miek@miek.nl>

* Dial doesnt need to be method an Forward either

Signed-off-by: Miek Gieben <miek@miek.nl>

* Address comments

Address various comments on the PR.

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2018-07-09 15:14:55 +01:00
committed by GitHub
parent 4083852b70
commit a536833546
13 changed files with 77 additions and 76 deletions
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47
plugin/forward/health.go
View File

@@ -1,17 +1,48 @@
package forward
import (
"crypto/tls"
"sync/atomic"
"time"
"github.com/miekg/dns"
)
// HealthChecker checks the upstream health.
type HealthChecker interface {
Check(*Proxy) error
SetTLSConfig(*tls.Config)
}
// dnsHc is a health checker for a DNS endpoint (DNS, and DoT).
type dnsHc struct{ c *dns.Client }
// NewHealthChecker returns a new HealthChecker based on protocol.
func NewHealthChecker(protocol int) HealthChecker {
switch protocol {
case DNS, TLS:
c := new(dns.Client)
c.Net = "udp"
c.ReadTimeout = 1 * time.Second
c.WriteTimeout = 1 * time.Second
return &dnsHc{c: c}
}
return nil
}
func (h *dnsHc) SetTLSConfig(cfg *tls.Config) {
h.c.Net = "tcp-tls"
h.c.TLSConfig = cfg
}
// For HC we send to . IN NS +norec message to the upstream. Dial timeouts and empty
// replies are considered fails, basically anything else constitutes a healthy upstream.
// Check is used as the up.Func in the up.Probe.
func (p *Proxy) Check() error {
err := p.send()
func (h *dnsHc) Check(p *Proxy) error {
err := h.send(p.addr)
if err != nil {
HealthcheckFailureCount.WithLabelValues(p.addr).Add(1)
atomic.AddUint32(&p.fails, 1)
@@ -22,14 +53,14 @@ func (p *Proxy) Check() error {
return nil
}
func (p *Proxy) send() error {
hcping := new(dns.Msg)
hcping.SetQuestion(".", dns.TypeNS)
func (h *dnsHc) send(addr string) error {
ping := new(dns.Msg)
ping.SetQuestion(".", dns.TypeNS)
m, _, err := p.client.Exchange(hcping, p.addr)
// If we got a header, we're alright, basically only care about I/O errors 'n stuff
m, _, err := h.c.Exchange(ping, addr)
// If we got a header, we're alright, basically only care about I/O errors 'n stuff.
if err != nil && m != nil {
// Silly check, something sane came back
// Silly check, something sane came back.
if m.Response || m.Opcode == dns.OpcodeQuery {
err = nil
}