[dns] #support dns lookup

Author: brewlin

README.md

@@ -16,7 +16,7 @@
 ## @application 应用层
 - [x] [http](http://wiki.brewlin.com/wiki/net-protocol/index/)
 - [x] [websocket](http://wiki.brewlin.com/wiki/net-protocol/index/)
-- [ ] [dns](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [dns](http://wiki.brewlin.com/wiki/net-protocol/index/)
 
 
 ## @transport 传输层

cmd/application/dns/main.go

@@ -3,13 +3,27 @@ package main
 import (
 	"fmt"
 	"github.com/brewlin/net-protocol/protocol/application/dns"
+	"github.com/brewlin/net-protocol/protocol/header"
 )
 
 func main() {
-	dns := dns.NewEndpoint("www.baidu.com")
-	ir,err := dns.Resolve();
-	fmt.Println(err)
-	fmt.Println(string(ir))
+	d := dns.NewEndpoint("www.baidu.com")
+			fmt.Println("DNS lookuphost    : www.baidu.com")
+	defer d.Close()
+
+	ir,err := d.Resolve();
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	for _,v := range *ir {
+		switch v.Type {
+		case header.A:
+			fmt.Println("A(host name)      :",v.Address)
+		case header.CNAME:
+			fmt.Println("CNAME (alias name):",v.Address)
+		}
+	}
 
 
 }

protocol/application/dns/endopoint.go

@@ -1,42 +1,52 @@
 package dns
 
 import (
+	_ "github.com/brewlin/net-protocol/pkg/logging"
 	"github.com/brewlin/net-protocol/protocol/header"
 	"github.com/brewlin/net-protocol/protocol/transport/udp/client"
-	_ "github.com/brewlin/net-protocol/pkg/logging"
 )
 var gid  uint16 =  0x0010
 
 type Endpoint struct {
 	ID uint16
 	Domain string
 
+	//req data
+	req *header.DNS
+	resp *header.DNS
+
+	answer *[]header.DNSResource
+
 	c *client.Client
 }
 //NewEndpoint
+//support single domain query
 func NewEndpoint(domain string)*Endpoint{
 	id := gid + 1
 	return &Endpoint{
 		Domain:domain,
 		c:client.NewClient("8.8.8.8",53),
+		//c:client.NewClient("114.114.114.114",53),
 		ID:id,
 	}
 }
 //Resolve
-func (e *Endpoint) Resolve()([]byte,error){
+func (e *Endpoint) Resolve() ( *[]header.DNSResource,error ) {
+
 	h := header.DNS(make([]byte,12))
 	h.Setheader(e.ID)
-	h.SetQdcount(1)
-	h.SetAncount(0)
-	h.SetNscount(0)
-	h.SetQAcount(0)
-	h.SetDomain(e.Domain)
-	h.SetQuestion(1,1)
-	e.c.Connect()
-	e.c.Write(h)
-	return e.c.Read()
-
-
+	h.SetCount(1,0,0,0)
+	h.SetQuestion(e.Domain,1,1)
+	e.req = &h
+	return e.sendQuery()
+}
+//GetResp()
+func (e *Endpoint) GetResp() *header.DNS{
+	return e.resp
+}
+//Close close
+func (e *Endpoint) Close(){
+	e.c.Close()
 }
 
 

protocol/application/dns/query.go

@@ -0,0 +1,15 @@
+package dns
+
+import "github.com/brewlin/net-protocol/protocol/header"
+
+//sendQuery udp query dns
+func (e *Endpoint) sendQuery () ( *[]header.DNSResource ,error ) {
+
+	if err := e.c.Connect();err != nil {
+		return nil,err
+	}
+	if err := e.c.Write(*e.req) ; err != nil {
+		return nil,err
+	}
+	return e.parseResp()
+}

protocol/application/dns/rsp.go

@@ -0,0 +1,57 @@
+package dns
+
+import (
+	"github.com/brewlin/net-protocol/protocol/header"
+	"strconv"
+	"strings"
+)
+
+//parseResp
+//解析响应
+func (e *Endpoint) parseResp() (*[]header.DNSResource,error){
+	rsp,err := e.c.Read()
+	if err != nil {
+		return nil,err
+	}
+	p := header.DNS(rsp)
+	e.resp = &p
+	e.answer = p.GetAnswer(e.Domain)
+	return e.parseAnswer()
+}
+
+func (e *Endpoint) parseAnswer()(*[]header.DNSResource,error){
+	for i := 0; i < len(*e.answer) ; i++ {
+		switch (*e.answer)[i].Type {
+		case header.A:
+			(*e.answer)[i].Address = e.parseAName((*e.answer)[i].RData)
+		case header.CNAME:
+			(*e.answer)[i].Address = e.parseCName((*e.answer)[i].RData)
+		}
+	}
+	return e.answer,nil
+}
+func (e *Endpoint)parseAName(rd []byte) string {
+	res := []string{}
+	for _,v := range rd {
+		res = append(res,strconv.Itoa(int(v)))
+	}
+	return strings.Join(res,".")
+}
+
+func (e *Endpoint)parseCName(rd []byte) (res string) {
+
+	for{
+		l := int(rd[0])
+		if l >= len(rd){
+			res += ".com"
+			return
+		}
+		rd = rd[1:]
+		res += string(rd[0:l])
+		rd = rd[l:]
+		if len(rd) == 0 {
+			return
+		}
+
+	}
+}

protocol/header/dns.go

@@ -6,82 +6,158 @@ import (
 	"strings"
 )
 
-//DNSResourceType resource type 表示资源类型
-type DNSResourceType uint16
-
-//DNSop 表示dns header 操作码
-type DNSop uint16
 
 //ADCOUNT question 实体数量占2个字节
 //ANCOUNT answer   资源数量占2个字节
 //NSCOUNT authority 部分包含的资源数量 2byte
 //ARCOUNT additional 部分包含的资源梳理 2byte
 
+//DNSResourceType resource type 表示资源类型
+type DNSResourceType uint16
+
+const (
+	A  DNSResourceType = iota + 1 // name = hostname value = ipaddress
+	NS                            //name = ,value = dns hostname
+	MD
+	MF
+	CNAME //name = hostname
+	SOA
+	MB
+	MG
+	MR
+	NULL
+	WKS
+	PTR
+	HINFO
+	MINFO
+	MX
+)
 
 const (
 	ID = 0
 	OP = 2
 	QDCOUNT = 4
 	ANCOUNT = 6
 	NSCOUNT = 8
-	QACOUNT = 10
+	ARCOUNT = 10
 
 	DOMAIN = 12
 )
-
+//DNSQuestion
 type DNSQuestion struct {
 	QuestionType  uint16
 	QuestionClass uint16
 }
 
+//DNSResource ansower,authority,additional
+type DNSResource struct {
+	Name uint16
+	Type DNSResourceType
+	Class uint16
+	TTL uint32
+	RDlen uint16
+	RData []byte
+	Address string
+}
+
+
 //DNS 报文的封装
 type DNS []byte
 
+//GetId
+func (d DNS) GetId() uint16 {
+	return binary.BigEndian.Uint16(d[ID:OP])
+}
+//GetQDCount
+func (d DNS) GetQDCount()uint16  {
+	return binary.BigEndian.Uint16(d[QDCOUNT:QDCOUNT+2])
+}
+//GetANCount
+func (d DNS) GetANCount()uint16{
+	return binary.BigEndian.Uint16(d[ANCOUNT:ANCOUNT + 2])
+}
+//GetNSCount
+func (d DNS) GetNSCount() uint16 {
+	return binary.BigEndian.Uint16(d[NSCOUNT:NSCOUNT + 2])
+}
+//GetQACount
+func (d DNS) GetARCount () uint16 {
+	return binary.BigEndian.Uint16(d[ARCOUNT:ARCOUNT + 2])
+}
+
+//GetAnswer
+func (d DNS) GetAnswer(domain string) *[]DNSResource {
+	//answer 起始地址
+	asLen := DOMAIN + len(d.getDomain(domain)) + 4
+
+	answer := []DNSResource{}
+	for i := 0; i < (int(d.GetANCount() + d.GetNSCount() + d.GetARCount())) ;i ++ {
+		rs := DNSResource{}
+		//判断是不是指针 pointer地址
+		if checkP := d[asLen]; checkP >> 6  == 3 {
+			//pointer := (d[asLen] & 0x3F << 8) + d[asLen+1]
+			rs.Name = binary.BigEndian.Uint16(d[asLen:asLen+2])
+			asLen += 2
+			rs.Type = DNSResourceType(binary.BigEndian.Uint16(d[asLen:asLen+2]))
+			asLen += 2
+			rs.Class = binary.BigEndian.Uint16(d[asLen:asLen+2])
+			asLen += 2
+			rs.TTL = binary.BigEndian.Uint32(d[asLen:asLen+4])
+			asLen += 4
+			rs.RDlen = binary.BigEndian.Uint16(d[asLen:asLen+2])
+			asLen += 2
+			rs.RData = d[asLen:asLen+int(rs.RDlen)]
+			asLen += int(rs.RDlen)
+			answer = append(answer,rs)
+		}
+	}
+	return &answer
+}
+
 //Setheader
 func (d DNS) Setheader(id uint16){
 	d.setID(id)
 	d.setFlag(0,0,0,0,1,0,0)
 }
-//SetID
-func (d DNS)setID(id uint16){
-	//set id
-	binary.BigEndian.PutUint16(d[ID:], id)
-}
-//SetQdcount
-func (d DNS)SetQdcount(qd uint16){
-
+//SetCount
+func (d DNS) SetCount(qd,an,ns,qa uint16) {
+	//SetQdcount
 	binary.BigEndian.PutUint16(d[QDCOUNT:], qd)
-}
-//SetAncount
-func (d DNS)SetAncount(an uint16){
+	//SetAncount
 	binary.BigEndian.PutUint16(d[ANCOUNT:] ,an)
-}
-//SetNscount
-func (d DNS)SetNscount(ns uint16){
+	//SetNscount
 	binary.BigEndian.PutUint16(d[NSCOUNT:],ns)
+	//SetQAcount
+	binary.BigEndian.PutUint16(d[ARCOUNT:],qa)
 }
-//SetQAcount
-func (d DNS)SetQAcount(qa uint16){
-	binary.BigEndian.PutUint16(d[QACOUNT:],qa)
+//setID
+func (d DNS)setID(id uint16){
+	//set id
+	binary.BigEndian.PutUint16(d[ID:], id)
 }
-//SetDomain
-func (d *DNS)SetDomain(domain string) {
+//setDomain
+func (d *DNS)getDomain(domain string) []byte {
 	var (
 		buffer   bytes.Buffer
 		segments []string = strings.Split(domain, ".")
 	)
-	binary.Write(&buffer,binary.BigEndian,*d)
-
 	for _, seg := range segments {
 		binary.Write(&buffer, binary.BigEndian, byte(len(seg)))
 		binary.Write(&buffer, binary.BigEndian, []byte(seg))
 	}
 	binary.Write(&buffer, binary.BigEndian, byte(0x00))
 
-	*d = buffer.Bytes()
-	//return buffer.Bytes()
+	return buffer.Bytes()
 }
-func (d *DNS)SetQuestion(qtype,qclass uint16){
+//SetQuestion query field
+//domain url
+//qtype type
+//qclass class
+func (d *DNS)SetQuestion(domain string,qtype,qclass uint16){
+	for _,b := range d.getDomain(domain) {
+		*d = append((*d),b)
+	}
+	//d.setDomain(domain)
 	q := DNSQuestion{
 		QuestionType:  qtype,
 		QuestionClass: qclass,

protocol/transport/udp/client/write.go

@@ -5,7 +5,7 @@ import (
 	tcpip "github.com/brewlin/net-protocol/protocol"
 )
 //Write
-func (c *Client) Write(buf []byte) error {
+func (c *Client) Write(buf []byte) *tcpip.Error {
 	v := buffer.View(buf)
 	for{
 		_,ch,err := c.ep.Write(tcpip.SlicePayload(v),