clash/dns/middleware.go
2019-09-21 10:30:43 +08:00

79 lines
1.6 KiB
Go

package dns
import (
"strings"
"github.com/Dreamacro/clash/component/fakeip"
"github.com/Dreamacro/clash/log"
D "github.com/miekg/dns"
)
type handler func(w D.ResponseWriter, r *D.Msg)
type middleware func(next handler) handler
func withFakeIP(fakePool *fakeip.Pool) middleware {
return func(next handler) handler {
return func(w D.ResponseWriter, r *D.Msg) {
q := r.Question[0]
if q.Qtype == D.TypeAAAA {
D.HandleFailed(w, r)
return
} else if q.Qtype != D.TypeA {
next(w, r)
return
}
host := strings.TrimRight(q.Name, ".")
rr := &D.A{}
rr.Hdr = D.RR_Header{Name: q.Name, Rrtype: D.TypeA, Class: D.ClassINET, Ttl: dnsDefaultTTL}
ip := fakePool.Lookup(host)
rr.A = ip
msg := r.Copy()
msg.Answer = []D.RR{rr}
setMsgTTL(msg, 1)
msg.SetReply(r)
w.WriteMsg(msg)
return
}
}
}
func withResolver(resolver *Resolver) handler {
return func(w D.ResponseWriter, r *D.Msg) {
msg, err := resolver.Exchange(r)
if err != nil {
q := r.Question[0]
log.Debugln("[DNS Server] Exchange %s failed: %v", q.String(), err)
D.HandleFailed(w, r)
return
}
msg.SetReply(r)
w.WriteMsg(msg)
return
}
}
func compose(middlewares []middleware, endpoint handler) handler {
length := len(middlewares)
h := endpoint
for i := length - 1; i >= 0; i-- {
middleware := middlewares[i]
h = middleware(h)
}
return h
}
func newHandler(resolver *Resolver) handler {
middlewares := []middleware{}
if resolver.IsFakeIP() {
middlewares = append(middlewares, withFakeIP(resolver.pool))
}
return compose(middlewares, withResolver(resolver))
}