100 lines
2.4 KiB
Go
100 lines
2.4 KiB
Go
package main
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import (
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"context"
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"fmt"
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"log"
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"os"
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"os/signal"
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"syscall"
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dnsProxy "kvas2-go/dns-proxy"
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iptablesHelper "kvas2-go/iptables-helper"
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ruleComposer "kvas2-go/rule-composer"
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)
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var (
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ChainPostfix = "KVAS2"
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ListenPort = uint16(7548)
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TargetDNSServerAddress = "127.0.0.1:53"
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)
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func main() {
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records := ruleComposer.NewRecords()
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proxy := dnsProxy.New(ListenPort, TargetDNSServerAddress)
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dnsOverrider, err := iptablesHelper.NewDNSOverrider(fmt.Sprintf("%s_DNSOVERRIDER", ChainPostfix), ListenPort)
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if err != nil {
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log.Fatalf("failed to initialize DNS overrider: %v", err)
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}
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proxy.MsgHandler = func(msg *dnsProxy.Message) {
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printKnownRecords := func() {
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for _, q := range msg.QD {
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fmt.Printf("%04x: DBG Known addresses for: %s\n", msg.ID, q.QName.String())
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for idx, addr := range records.GetARecords(q.QName.String(), true) {
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fmt.Printf("%04x: #%d: %s\n", msg.ID, idx, addr.String())
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}
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}
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}
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parseResponseRecord := func(rr dnsProxy.ResourceRecord) {
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switch v := rr.(type) {
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case dnsProxy.Address:
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fmt.Printf("%04x: -> A: Name: %s; Address: %s; TTL: %d\n", msg.ID, v.Name, v.Address.String(), v.TTL)
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records.PutARecord(v.Name.String(), v.Address, int64(v.TTL))
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case dnsProxy.CName:
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fmt.Printf("%04x: -> CNAME: Name: %s; CName: %s\n", msg.ID, v.Name, v.CName)
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records.PutCNameRecord(v.Name.String(), v.CName.String(), int64(v.TTL))
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default:
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fmt.Printf("%04x: -> Unknown: %x\n", msg.ID, v.EncodeResource())
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}
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}
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printKnownRecords()
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for _, q := range msg.QD {
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fmt.Printf("%04x: <- Request name: %s\n", msg.ID, q.QName.String())
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}
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for _, a := range msg.AN {
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parseResponseRecord(a)
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}
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for _, a := range msg.NS {
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parseResponseRecord(a)
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}
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for _, a := range msg.AR {
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parseResponseRecord(a)
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}
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printKnownRecords()
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}
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ctx, cancel := context.WithCancel(context.Background())
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go func() {
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err := proxy.Listen(ctx)
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if err != nil {
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log.Fatalf("failed to initialize DNS proxy: %v", err)
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}
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}()
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err = dnsOverrider.Enable()
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if err != nil {
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log.Fatalf("failed to override DNS: %v", err)
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}
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fmt.Printf("Started service on port '%d'\n", ListenPort)
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c := make(chan os.Signal, 1)
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signal.Notify(c, os.Interrupt, syscall.SIGTERM)
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for {
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select {
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case <-c:
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fmt.Println("Graceful shutdown...")
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cancel()
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err = dnsOverrider.Disable()
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if err != nil {
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log.Fatalf("failed to rollback override DNS changes: %v", err)
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}
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return
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}
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}
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}
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