[dns] #done dns protocol package send construct

Author: brewlin

README.md

@@ -14,32 +14,34 @@
 ```
 `./cmd/*.md`
 ## @application 应用层
-- [x] http [docs](./cmd/http.md)
-- [x] websocket [docs](./cmd/websocket.md)
+- [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/)
+
 
 ## @transport 传输层
-- [x] tcp [docs](./cmd/tcp.md)
-- [x] udp [docs](./cmd/udp.md)
-- [x] port 端口机制
+- [x] [tcp](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [udp](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [port](http://wiki.brewlin.com/wiki/net-protocol/index/) 端口机制 
 
 ## @network 网络层
-- [x] icmp
-- [x] ipv4
-- [x] ipv6
+- [x] [icmp](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [ipv4](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [ipv6](http://wiki.brewlin.com/wiki/net-protocol/index/)
 
 ## @link 链路层
-- [x] arp [docs](./cmd/arp.md)
-- [x] ethernet
+- [x] [arp](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [ethernet](http://wiki.brewlin.com/wiki/net-protocol/index/) 
 
 ## @物理层
-- [x] tun tap 虚拟网卡的实现
+- [x] tun [tap](http://wiki.brewlin.com/wiki/net-protocol/index/) 虚拟网卡的实现
 
 ## @客户端
 发起客户端请求
-- [x] http client 
-- [x] websocket client 
-- [x] tcp client
-- [x] udp client
+- [x] [http client](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [websocket client](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [tcp client](http://wiki.brewlin.com/wiki/net-protocol/index/)
+- [x] [udp client](http://wiki.brewlin.com/wiki/net-protocol/index/)
 ## 协议相关api
 ### 1.应用层相关协议
 应用层暂时只实现了`http`、`websocket`等文本协议。都基于tcp、对tcp等进行二次封装

cmd/application/dns/main.go

@@ -0,0 +1,15 @@
+package main
+
+import (
+	"fmt"
+	"github.com/brewlin/net-protocol/protocol/application/dns"
+)
+
+func main() {
+	dns := dns.NewEndpoint("www.baidu.com")
+	ir,err := dns.Resolve();
+	fmt.Println(err)
+	fmt.Println(string(ir))
+
+	
+}

protocol/application/dns/endopoint.go

@@ -1,6 +1,43 @@
 package dns
 
-type endpoint struct {
+import (
+	"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
+
+	c *client.Client
+}
+//NewEndpoint
+func NewEndpoint(domain string)*Endpoint{
+	id := gid + 1
+	return &Endpoint{
+		Domain:domain,
+		c:client.NewClient("8.8.8.8",53),
+		ID:id,
+	}
 }
+//Resolve
+func (e *Endpoint) Resolve()([]byte,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()
+
+
+}
+
+
 

protocol/header/dns.go

@@ -1,74 +1,115 @@
 package header
 
+import (
+	"bytes"
+	"encoding/binary"
+	"strings"
+)
+
 //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
-)
-
 //DNSop 表示dns header 操作码
 type DNSop uint16
 
-//1(QR)+4(OPCODE)+1(AA)+1(TC)+1(RD)+1(RA)+3(Z)+4(RCODE)
-const (
-	//dns请求
-	DNSRequest DNSop = 0
-	//dns应答
-	DNSReply DNSop = 1
+//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
+
 
-	//opcode 标准请求
-	DNSOpcodeQ DNSop = 0 << 1
-	//opcode 反转查询
-	DNSOpcodeR DNSop = 1 << 1
-	//opcode 服务器状态查询
-	DNSOpcodeS DNSop = 2 << 1
+const (
+	ID = 0
+	OP = 2
+	QDCOUNT = 4
+	ANCOUNT = 6
+	NSCOUNT = 8
+	QACOUNT = 10
 
-	//权威应答
-	DNSAaN DNSop = 0 << 5
-	DNSAaY DNSop = 1 << 5
+	DOMAIN = 12
+)
 
-	//截断
-	DNSTcN DNSop = 0 << 6
-	DNSTcY DNSop = 1 << 6
+type DNSQuestion struct {
+	QuestionType  uint16
+	QuestionClass uint16
+}
 
-	//期望递归
-	DNSRdN DNSop = 0 << 7
-	DNSRdY DNSop = 1 << 7
+//DNS 报文的封装
+type DNS []byte
 
-	//递归可用性
-	DNSRaN DNSop = 0 << 8
-	DNSRaY DNSop = 1 << 8
+//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){
 
-	//保留备用 占3位 + 3
+	binary.BigEndian.PutUint16(d[QDCOUNT:], qd)
+}
+//SetAncount
+func (d DNS)SetAncount(an uint16){
+	binary.BigEndian.PutUint16(d[ANCOUNT:] ,an)
+}
+//SetNscount
+func (d DNS)SetNscount(ns uint16){
+	binary.BigEndian.PutUint16(d[NSCOUNT:],ns)
+}
+//SetQAcount
+func (d DNS)SetQAcount(qa uint16){
+	binary.BigEndian.PutUint16(d[QACOUNT:],qa)
+}
+//SetDomain
+func (d *DNS)SetDomain(domain string) {
+	var (
+		buffer   bytes.Buffer
+		segments []string = strings.Split(domain, ".")
+	)
+	binary.Write(&buffer,binary.BigEndian,*d)
 
-	//RCODE 响应code 占4位
-	DNSRocdeN   DNSop = 0 << 12
-	DNSRocdeF   DNSop = 1 << 12
-	DNSRocdeS   DNSop = 2 << 12
-	DNSRocdeNa  DNSop = 3 << 12
-	DNSRocdeNot DNSop = 4 << 12
-	DNSRocdeRef DNSop = 5 << 12
-)
+	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))
 
-//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
+	*d = buffer.Bytes()
+	//return buffer.Bytes()
+}
+func (d *DNS)SetQuestion(qtype,qclass uint16){
+	q := DNSQuestion{
+		QuestionType:  qtype,
+		QuestionClass: qclass,
+	}
+	var buffer bytes.Buffer
+	binary.Write(&buffer,binary.BigEndian,*d)
+	binary.Write(&buffer,binary.BigEndian,q)
+	*d = buffer.Bytes()
+}
 
-//DNS 报文的封装
-type DNS []byte
+//SetFlag
+//QR 表示请求还是响应
+//OPCODE 1表示反转查询；2表示服务器状态查询。3~15目前保留，以备将来使用
+//AA 表示响应的服务器是否是权威DNS服务器。只在响应消息中有效。
+//TC 指示消息是否因为传输大小限制而被截断
+//RD 该值在请求消息中被设置，响应消息复用该值。如果被设置，表示希望服务器递归查询。但服务器不一定支持递归查询
+//RA 。该值在响应消息中被设置或被清除，以表明服务器是否支持递归查询。
+//Z 保留备用
+//RCODE: 该值在响应消息中被设置。取值及含义如下：
+//0：No error condition，没有错误条件；
+//1：Format error，请求格式有误，服务器无法解析请求；
+//2：Server failure，服务器出错。
+//3：Name Error，只在权威DNS服务器的响应中有意义，表示请求中的域名不存在。
+//4：Not Implemented，服务器不支持该请求类型。
+//5：Refused，服务器拒绝执行请求操作。
+//6~15：保留备用
+func (d DNS) setFlag(QR uint16, OPCODE uint16, AA uint16, TC uint16, RD uint16, RA uint16, RCODE uint16) {
+	//set flag
+	op :=  QR<<15 + OPCODE<<11 + AA<<10 + TC<<9 + RD<<8 + RA<<7 + RCODE
+	binary.BigEndian.PutUint16(d[OP:],op)
+}