73 lines
1.6 KiB
Go
73 lines
1.6 KiB
Go
package forward
|
|
|
|
import (
|
|
"crypto/tls"
|
|
"sync/atomic"
|
|
"time"
|
|
|
|
"github.com/coredns/coredns/plugin/pkg/transport"
|
|
|
|
"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 transport.
|
|
func NewHealthChecker(trans string) HealthChecker {
|
|
switch trans {
|
|
case transport.DNS, transport.TLS:
|
|
c := new(dns.Client)
|
|
c.Net = "udp"
|
|
c.ReadTimeout = 1 * time.Second
|
|
c.WriteTimeout = 1 * time.Second
|
|
|
|
return &dnsHc{c: c}
|
|
}
|
|
|
|
log.Warningf("No healthchecker for transport %q", trans)
|
|
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 (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)
|
|
return err
|
|
}
|
|
|
|
atomic.StoreUint32(&p.fails, 0)
|
|
return nil
|
|
}
|
|
|
|
func (h *dnsHc) send(addr string) error {
|
|
ping := new(dns.Msg)
|
|
ping.SetQuestion(".", dns.TypeNS)
|
|
|
|
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.
|
|
if m.Response || m.Opcode == dns.OpcodeQuery {
|
|
err = nil
|
|
}
|
|
}
|
|
|
|
return err
|
|
}
|