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dns: move tcp and udp process to handleReqMsg function
This commit is contained in:
nadoo
parent
d2d49e7d2e
commit
8a1111d3b5
131
dns.go
131
dns.go
@ -4,8 +4,7 @@ package main
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import (
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"errors"
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"io"
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"net"
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"strings"
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@ -110,77 +109,15 @@ func (s *DNS) ListenAndServeUDP() {
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data = data[:n]
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go func() {
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query := parseQuery(data)
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domain := query.DomainName
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dnsServer := s.GetServer(domain)
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if s.tunnel {
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dnsServer = s.dnsServer
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}
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rc, err := s.sDialer.NextDialer(domain+":53").Dial("tcp", dnsServer)
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if err != nil {
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logf("proxy-dns failed to connect to server %v: %v", dnsServer, err)
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return
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}
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defer rc.Close()
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// 2 bytes length after tcp header, before dns message
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reqLen := make([]byte, 2)
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binary.BigEndian.PutUint16(reqLen, uint16(len(data)))
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rc.Write(reqLen)
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rc.Write(data)
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// fmt.Printf("dns req len %d:\n%s\n\n", reqLen, hex.Dump(data[:]))
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var respLen uint16
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err = binary.Read(rc, binary.BigEndian, &respLen)
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if err != nil {
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logf("proxy-dns error in read respLen %s\n", err)
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return
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}
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respMsg := make([]byte, respLen)
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_, err = io.ReadFull(rc, respMsg)
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if err != nil {
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logf("proxy-dns error in read respMsg %s\n", err)
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return
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}
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// fmt.Printf("dns resp len %d:\n%s\n\n", respLen, hex.Dump(respMsg[:]))
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var ip string
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// length is not needed in udp dns response. (2 bytes)
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// SEE RFC1035, section 4.2.2 TCP: The message is prefixed with a two byte length field which gives the message length, excluding the two byte length field.
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if respLen > 0 {
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// run handle functions before send to client so RULE and IPSET can take effect
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// TODO: add PRE_HANDLERS
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query := parseQuery(respMsg)
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if (query.QueryType == DNSQueryTypeA || query.QueryType == DNSQueryTypeAAAA) &&
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len(respMsg) > query.Offset {
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answers := parseAnswers(respMsg[query.Offset:])
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for _, answer := range answers {
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if answer.IP != "" {
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ip += answer.IP + ","
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}
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for _, h := range s.answerHandlers {
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h(query.DomainName, answer.IP)
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}
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}
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}
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_, respMsg := s.handleReqMsg(uint16(len(data)), data)
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_, err = c.WriteTo(respMsg, clientAddr)
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if err != nil {
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logf("proxy-dns error in local write: %s\n", err)
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}
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}
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logf("proxy-dns %s <-> %s, type: %d, %s: %s", clientAddr.String(), dnsServer, query.QueryType, domain, ip)
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// logf("proxy-dns %s <-> %s, type: %d, %s: %s", clientAddr.String(), dnsServer, query.QueryType, domain, ip)
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}()
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}
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@ -223,19 +160,37 @@ func (s *DNS) ServeTCP(c net.Conn) {
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reqMsg := make([]byte, reqLen)
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_, err := io.ReadFull(c, reqMsg)
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if err != nil {
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logf("proxy-dns-tcp error in read reqMsg %s\n", err)
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logf("proxy-dns-tcp error in read reqMsg %s", err)
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return
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}
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query := parseQuery(reqMsg)
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domain := query.DomainName
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respLen, respMsg := s.handleReqMsg(reqLen, reqMsg)
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dnsServer := s.GetServer(domain)
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if err := binary.Write(c, binary.BigEndian, respLen); err != nil {
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logf("proxy-dns-tcp error in local write respLen: %s\n", err)
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}
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if err := binary.Write(c, binary.BigEndian, respMsg); err != nil {
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logf("proxy-dns-tcp error in local write respMsg: %s\n", err)
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}
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// logf("proxy-dns-tcp %s <-> %s, type: %d, %s: %s", c.RemoteAddr(), dnsServer, query.QueryType, domain, ip)
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}
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// handle request msg and return response msg
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func (s *DNS) handleReqMsg(reqLen uint16, reqMsg []byte) (respLen uint16, respMsg []byte) {
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query, err := parseQuery(reqMsg)
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if err != nil {
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logf("proxy-dns-tcp error in parseQuery reqMsg %s", err)
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return
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}
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dnsServer := s.GetServer(query.DomainName)
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if s.tunnel {
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dnsServer = s.dnsServer
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}
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rc, err := s.sDialer.NextDialer(domain+":53").Dial("tcp", dnsServer)
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rc, err := s.sDialer.NextDialer(query.DomainName+":53").Dial("tcp", dnsServer)
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if err != nil {
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logf("proxy-dns failed to connect to server %v: %v", dnsServer, err)
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return
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@ -243,30 +198,34 @@ func (s *DNS) ServeTCP(c net.Conn) {
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defer rc.Close()
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if err := binary.Write(rc, binary.BigEndian, reqLen); err != nil {
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logf("proxy-dns failed to connect to server %v: %v", dnsServer, err)
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}
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if err := binary.Write(rc, binary.BigEndian, reqMsg); err != nil {
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logf("proxy-dns failed to connect to server %v: %v", dnsServer, err)
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}
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var respLen uint16
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if err := binary.Read(rc, binary.BigEndian, &respLen); err != nil {
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logf("proxy-dns-tcp failed to read response length: %v", err)
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return
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}
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respMsg := make([]byte, respLen)
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respMsg = make([]byte, respLen)
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_, err = io.ReadFull(rc, respMsg)
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if err != nil {
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logf("proxy-dns-tcp error in read respMsg %s\n", err)
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return
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}
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fmt.Printf("dns resp len %d:\n%s\n\n", respLen, hex.Dump(respMsg[:]))
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// fmt.Printf("dns resp len %d:\n%s\n\n", respLen, hex.Dump(respMsg[:]))
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var ip string
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if respLen > 0 {
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query := parseQuery(respMsg)
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query, err := parseQuery(respMsg)
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if err != nil {
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logf("proxy-dns error in parseQuery respMsg %s", err)
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return
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}
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if (query.QueryType == DNSQueryTypeA || query.QueryType == DNSQueryTypeAAAA) &&
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len(respMsg) > query.Offset {
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@ -283,16 +242,9 @@ func (s *DNS) ServeTCP(c net.Conn) {
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}
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}
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if err := binary.Write(c, binary.BigEndian, respLen); err != nil {
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logf("proxy-dns-tcp error in local write respLen: %s\n", err)
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}
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if err := binary.Write(c, binary.BigEndian, respMsg); err != nil {
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logf("proxy-dns-tcp error in local write respMsg: %s\n", err)
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}
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}
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logf("proxy-dns-tcp %s <-> %s, type: %d, %s: %s", c.RemoteAddr(), dnsServer, query.QueryType, domain, ip)
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return
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}
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// SetServer .
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@ -321,7 +273,7 @@ func (s *DNS) AddAnswerHandler(h DNSAnswerHandler) {
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s.answerHandlers = append(s.answerHandlers, h)
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}
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func parseQuery(p []byte) *dnsQuery {
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func parseQuery(p []byte) (*dnsQuery, error) {
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q := &dnsQuery{}
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var i int
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@ -341,11 +293,16 @@ func parseQuery(p []byte) *dnsQuery {
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}
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q.DomainName = string(domain[:len(domain)-1])
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if len(p) < i+4 {
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return nil, errors.New("parseQuery error, not enough data")
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}
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q.QueryType = binary.BigEndian.Uint16(p[i:])
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q.QueryClass = binary.BigEndian.Uint16(p[i+2:])
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q.Offset = i + 4
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return q
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return q, nil
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}
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func parseAnswers(p []byte) []*dnsAnswer {
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