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