/
upstream.go
55 lines (47 loc) · 904 Bytes
/
upstream.go
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package mupstream
import (
"net"
"time"
"github.com/miekg/dns"
)
var checkClient = &dns.Client{
Net: "tcp",
ReadTimeout: 2 * time.Second,
WriteTimeout: 2 * time.Second,
}
type upstream struct {
addr string
srtt float32
fails uint32
client *dns.Client
}
func newUpstream(addr string) *upstream {
return &upstream{
addr: addr,
client: &dns.Client{
Net: "udp",
Dialer: &net.Dialer{
KeepAlive: time.Minute,
},
Timeout: 300 * time.Millisecond,
},
}
}
func (u *upstream) String() string {
return u.addr
}
func (u *upstream) srttAttenuation() {
u.srtt *= 0.98
}
func (u *upstream) forward(m *dns.Msg) (*dns.Msg, time.Duration, error) {
resp, rtt, err := u.client.Exchange(m, u.addr)
if err != nil { //
u.srtt = u.srtt + 200
} else { // success
if rtt > 300 {
rtt = 300
}
u.srtt = u.srtt*0.7 + float32(rtt)*0.3
}
return resp, rtt, err
}