mirror of
https://github.com/nadoo/glider.git
synced 2025-02-23 17:35:40 +08:00
dns: add the ability to get resloved ip address of domain. (so we can add ip address to ipset later)
This commit is contained in:
nadoo
parent
dbc9fc7b5c
commit
dd5ba37582
116
dns.go
116
dns.go
@ -9,20 +9,44 @@ import (
|
||||
"strings"
|
||||
)
|
||||
|
||||
// UDPDNSHeaderLen is the length of UDP dns msg header
|
||||
const UDPDNSHeaderLen = 12
|
||||
// DNSUDPHeaderLen is the length of UDP dns msg header
|
||||
const DNSUDPHeaderLen = 12
|
||||
|
||||
// TCPDNSHEADERLen is the length of TCP dns msg header
|
||||
const TCPDNSHEADERLen = 2 + UDPDNSHeaderLen
|
||||
// DNSTCPHeaderLen is the length of TCP dns msg header
|
||||
const DNSTCPHeaderLen = 2 + DNSUDPHeaderLen
|
||||
|
||||
// MaxUDPDNSLen is the max size of udp dns request.
|
||||
// DNSUDPMaxLen is the max size of udp dns request.
|
||||
// https://tools.ietf.org/html/rfc1035#section-4.2.1
|
||||
// Messages carried by UDP are restricted to 512 bytes (not counting the IP
|
||||
// or UDP headers). Longer messages are truncated and the TC bit is set in
|
||||
// the header.
|
||||
// TODO: If the request length > 512 then the client will send TCP packets instead,
|
||||
// so we should also serve tcp requests.
|
||||
const MaxUDPDNSLen = 512
|
||||
const DNSUDPMaxLen = 512
|
||||
|
||||
// DNSQueryTypeA ipv4
|
||||
const DNSQueryTypeA = 1
|
||||
|
||||
// DNSQueryTypeAAAA ipv6
|
||||
const DNSQueryTypeAAAA = 28
|
||||
|
||||
type dnsQuery struct {
|
||||
DomainName string
|
||||
QueryType uint16
|
||||
QueryClass uint16
|
||||
Offset int
|
||||
}
|
||||
|
||||
type dnsAnswer struct {
|
||||
DomainName string
|
||||
QueryType uint16
|
||||
QueryClass uint16
|
||||
TTL uint32
|
||||
DataLength uint16
|
||||
Data []byte
|
||||
|
||||
IP string
|
||||
}
|
||||
|
||||
// DNS .
|
||||
type DNS struct {
|
||||
@ -55,7 +79,7 @@ func (s *DNS) ListenAndServe() {
|
||||
logf("listening UDP on %s", s.addr)
|
||||
|
||||
for {
|
||||
data := make([]byte, MaxUDPDNSLen)
|
||||
data := make([]byte, DNSUDPMaxLen)
|
||||
|
||||
n, clientAddr, err := l.ReadFrom(data)
|
||||
if err != nil {
|
||||
@ -67,7 +91,8 @@ func (s *DNS) ListenAndServe() {
|
||||
|
||||
go func() {
|
||||
// TODO: check domain rules and get a proper upstream name server.
|
||||
domain := string(getDomain(data))
|
||||
query := parseQuery(data)
|
||||
domain := query.DomainName
|
||||
|
||||
dnsServer := s.GetServer(domain)
|
||||
// TODO: check here
|
||||
@ -78,8 +103,6 @@ func (s *DNS) ListenAndServe() {
|
||||
}
|
||||
defer rc.Close()
|
||||
|
||||
logf("proxy-dns %s, %s <-> %s", domain, clientAddr.String(), dnsServer)
|
||||
|
||||
// 2 bytes length after tcp header, before dns message
|
||||
length := make([]byte, 2)
|
||||
binary.BigEndian.PutUint16(length, uint16(len(data)))
|
||||
@ -92,16 +115,32 @@ func (s *DNS) ListenAndServe() {
|
||||
return
|
||||
}
|
||||
|
||||
var ip string
|
||||
// length is not needed in udp dns response. (2 bytes)
|
||||
// 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.
|
||||
if len(resp) > 2 {
|
||||
msg := resp[2:]
|
||||
// TODO: Get IP from response, check and add to ipset
|
||||
query := parseQuery(msg)
|
||||
if len(msg) > query.Offset {
|
||||
answers := parseAnswers(msg[query.Offset:])
|
||||
for _, answer := range answers {
|
||||
if answer.IP != "" {
|
||||
ip += answer.IP + ","
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
_, err = l.WriteTo(msg, clientAddr)
|
||||
if err != nil {
|
||||
logf("error in local write: %s\n", err)
|
||||
}
|
||||
}
|
||||
|
||||
logf("proxy-dns %s, %s <-> %s, ip: %s", domain, clientAddr.String(), dnsServer, ip)
|
||||
|
||||
}()
|
||||
}
|
||||
}
|
||||
@ -127,26 +166,61 @@ func (s *DNS) GetServer(domain string) string {
|
||||
return s.dnsServer
|
||||
}
|
||||
|
||||
// getDomain from dns request playload, return []byte like:
|
||||
// []byte{'w', 'w', 'w', '.', 'm', 's', 'n', '.', 'c', 'o', 'm', '.'}
|
||||
// []byte("www.msn.com.")
|
||||
func getDomain(p []byte) []byte {
|
||||
var ret []byte
|
||||
func parseQuery(p []byte) *dnsQuery {
|
||||
q := &dnsQuery{}
|
||||
|
||||
for i := UDPDNSHeaderLen; i < len(p); {
|
||||
var i int
|
||||
var domain []byte
|
||||
for i = DNSUDPHeaderLen; i < len(p); {
|
||||
l := int(p[i])
|
||||
|
||||
if l == 0 {
|
||||
i++
|
||||
break
|
||||
}
|
||||
|
||||
ret = append(ret, p[i+1:i+l+1]...)
|
||||
ret = append(ret, '.')
|
||||
domain = append(domain, p[i+1:i+l+1]...)
|
||||
domain = append(domain, '.')
|
||||
|
||||
i = i + l + 1
|
||||
}
|
||||
|
||||
// TODO: check here
|
||||
// domain name could not be null, so the length of ret always >= 1?
|
||||
return ret[:len(ret)-1]
|
||||
q.DomainName = string(domain[:len(domain)-1])
|
||||
q.QueryType = binary.BigEndian.Uint16(p[i:])
|
||||
q.QueryClass = binary.BigEndian.Uint16(p[i+2:])
|
||||
q.Offset = i + 4
|
||||
|
||||
return q
|
||||
}
|
||||
|
||||
func parseAnswers(p []byte) []*dnsAnswer {
|
||||
var answers []*dnsAnswer
|
||||
|
||||
for i := 0; i < len(p); {
|
||||
l := int(p[i])
|
||||
|
||||
if l == 0 {
|
||||
i++
|
||||
break
|
||||
}
|
||||
|
||||
answer := &dnsAnswer{}
|
||||
answer.QueryType = binary.BigEndian.Uint16(p[i+2:])
|
||||
answer.QueryClass = binary.BigEndian.Uint16(p[i+4:])
|
||||
answer.TTL = binary.BigEndian.Uint32(p[i+6:])
|
||||
answer.DataLength = binary.BigEndian.Uint16(p[i+10:])
|
||||
answer.Data = p[i+12 : i+12+int(answer.DataLength)]
|
||||
|
||||
if answer.QueryType == DNSQueryTypeA {
|
||||
answer.IP = net.IP(answer.Data[:net.IPv4len]).String()
|
||||
} else if answer.QueryType == DNSQueryTypeAAAA {
|
||||
answer.IP = net.IP(answer.Data[:net.IPv6len]).String()
|
||||
}
|
||||
|
||||
answers = append(answers, answer)
|
||||
|
||||
i = i + 12 + int(answer.DataLength)
|
||||
}
|
||||
|
||||
return answers
|
||||
}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user