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tabVersion committed Apr 29, 2019
1 parent 594d740 commit 14c7ba1
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Showing 6 changed files with 41 additions and 40 deletions.
Binary file added pkg/windows_amd64/github.com/imroc/biu.a
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Empty file added src/dns-local.txt
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1 change: 1 addition & 0 deletions src/github.com/imroc/biu
Submodule biu added at 0376ce
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60 changes: 29 additions & 31 deletions src/main/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ import (
"time"
)

type DNSHeader struct {
type DNSHeader struct { // 描述 DNS 报文结构
id []byte
qr int64
operationCode int64
Expand All @@ -27,13 +27,13 @@ type DNSHeader struct {
ARCount int64
}

type DNSQuestion struct {
type DNSQuestion struct { // DNS 请求结构
questionName []byte
questionType []byte
questionClass []byte
}

type DNSAnswer struct {
type DNSAnswer struct { // DNS 应答结构
aname []byte
atype []byte
aclass []byte
Expand All @@ -42,13 +42,13 @@ type DNSAnswer struct {
rdata []byte
}

type DNSResponse struct {
type DNSResponse struct { // DNS 应答结构
header DNSHeader
question DNSQuestion
answer DNSAnswer
}

var questionTypeDict = map[int64]string{
var questionTypeDict = map[int64]string{ // 枚举请求类型
1: "A",
2: "NS",
5: "CNAME",
Expand All @@ -62,7 +62,7 @@ var questionTypeDict = map[int64]string{
255: "ANY",
}

func getHeader(data []byte) DNSHeader {
func getHeader(data []byte) DNSHeader { // 解析请求头部
flags := data[2:4]

flagsStr := biu.BytesToBinaryString(flags)
Expand All @@ -86,7 +86,7 @@ func getHeader(data []byte) DNSHeader {
return *header
}

func getQuestion(data []byte) DNSQuestion {
func getQuestion(data []byte) DNSQuestion { // 解析请求地址

qnameBytes := data[12 : len(data)-4]

Expand All @@ -99,8 +99,8 @@ func getQuestion(data []byte) DNSQuestion {
return *question
}

func Forward(data []byte, remoteDNS string) []byte {
socket, err := net.DialUDP("udp4", nil, &net.UDPAddr{
func Forward(data []byte, remoteDNS string) []byte { // 控制转发
socket, err := net.DialUDP("udp4", nil, &net.UDPAddr{ // 创建 socket 连接
IP: net.ParseIP(remoteDNS),
Port: 53,
})
Expand All @@ -110,7 +110,7 @@ func Forward(data []byte, remoteDNS string) []byte {
}
t := time.Now()

socket.SetDeadline(t.Add(time.Duration(5 * time.Second)))
socket.SetDeadline(t.Add(time.Duration(5 * time.Second))) // 设置超时时间

defer socket.Close()

Expand All @@ -120,22 +120,23 @@ func Forward(data []byte, remoteDNS string) []byte {
return nil
}

receiveData := make([]byte, 4096)
receiveData := make([]byte, 4096) // 创建缓冲区 大小为 4096 bytes
rn, remoteAddr, err := socket.ReadFromUDP(receiveData)
if err != nil {
log.Println("from ", remoteAddr, " read data failed!\n", err)
return nil
}
//log.Println(rn, remoteAddr)
//log.Printf("%x\n", receiveData[:rn])
// log.Println(rn, remoteAddr)
// log.Printf("%x\n", receiveData[:rn])

return receiveData[:rn]
}

func readConfig(dnsListPath string) map[string]string {
func readConfig(dnsListPath string) map[string]string { // 创建转发表
var dnsMap = map[string]string{}
var dnsListFile, _ = os.OpenFile(dnsListPath, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
defer dnsListFile.Close()

dnsListScanner := bufio.NewScanner(dnsListFile)
for dnsListScanner.Scan() {
ip := ""
Expand All @@ -151,7 +152,7 @@ func readConfig(dnsListPath string) map[string]string {
dnsArr := strings.Split(dnsList, " ")
if len(dnsArr) >= 2 {
for _, dnsStr := range dnsArr {
if isIP(dnsStr) {
if isIP(dnsStr) { // 识别是否是 IP 地址
ip = dnsStr
} else {
domain = dnsStr
Expand All @@ -164,17 +165,15 @@ func readConfig(dnsListPath string) map[string]string {
} else {
log.Printf("dns config error, please check %s", dnsList)
}

}
log.Printf("current dns setting: %q", dnsMap)
log.Printf("current dns setting: %q", dnsMap) // 输出当前的 IP cache 包括缓存和拒绝服务的列表
if len(dnsMap) != 0 {
return dnsMap
return dnsMap // 确保返回的列表非空
}
return nil
}

func cacheDNS(header DNSHeader, question DNSQuestion, ip string) []byte {

func cacheDNS(header DNSHeader, question DNSQuestion, ip string) []byte { // 构造缓存中的 dns 报文
response := DNSResponse{}

response.header.id = header.id
Expand All @@ -201,7 +200,6 @@ func cacheDNS(header DNSHeader, question DNSQuestion, ip string) []byte {
response.answer.rdata = ipAddrToByte(ip)

return reslove(response)

}

func reslove(response DNSResponse) []byte {
Expand Down Expand Up @@ -302,7 +300,7 @@ func main() {
}
*/

func refuseDNS(header DNSHeader, question DNSQuestion, ip string) []byte {
func refuseDNS(header DNSHeader, question DNSQuestion, ip string) []byte { // 创建拒绝服务的 dns 报文
response := DNSResponse{}

response.header.id = header.id
Expand Down Expand Up @@ -331,7 +329,7 @@ func refuseDNS(header DNSHeader, question DNSQuestion, ip string) []byte {
return reslove(response)
}

func unsupportDNS(header DNSHeader, question DNSQuestion, ip string) []byte {
func unsupportDNS(header DNSHeader, question DNSQuestion, ip string) []byte { // 创建不支持协议的 dns 报文
response := DNSResponse{}

response.header.id = header.id
Expand Down Expand Up @@ -370,11 +368,11 @@ func main() {
var dnsListPath string
flag.StringVar(&remoteDNS, "remoteDNS", "8.8.8.8", "Forwarding DNS server")
flag.StringVar(&dnsListPath, "dnsListPath", "./dns-local.txt", "dns relay config file path")
flag.Parse()
flag.Parse() // 解析传入参数

dnsMap := readConfig(dnsListPath)

listener, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: 53})
listener, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: 53}) // 开始监听 127.0.0.1:53

if err != nil {
log.Println(err)
Expand All @@ -394,7 +392,7 @@ func main() {
log.Printf("error during read: %s\n", readErr)
}
// start a thread once hearing from UDP
go func(ch byteTransefer) {
go func(ch byteTransefer) { // 多线程查询
debug("start func\n")
data := ch.data
n := ch.n
Expand All @@ -406,7 +404,7 @@ func main() {
//log.Printf("====> get questionName %s and its cache %s\n", parseDomain(question.questionName), dnsMap[parseDomain(question.questionName)])

//log.Printf("question %+v === type: %d\n", question, BytesToInt64(question.questionType))
if BytesToInt64(question.questionType) != 1 {
if BytesToInt64(question.questionType) != 1 { // 检查协议 v4 only
rep := unsupportDNS(header, question, "0.0.0.0")
_, writeErr := listener.WriteToUDP(rep, remoteAddr)

Expand All @@ -415,18 +413,18 @@ func main() {
} else {
log.Printf("[unsupport protocal] %s ", parseDomain(question.questionName))
}
return
return // 若协议不匹配直接丢弃
}

if dnsMap == nil || dnsMap[parseDomain(question.questionName)] == "" {
if dnsMap == nil || dnsMap[parseDomain(question.questionName)] == "" { // 表中没有记录的项 进行转发 ===> 中继
log.Printf("forward %s to %s\n", parseDomain(question.questionName), remoteDNS)
_, writeErr := listener.WriteToUDP(Forward(data[:n], remoteDNS), remoteAddr)

if writeErr != nil {
log.Printf("error during write: %s\n", writeErr)
}
return
} else if dnsMap[parseDomain(question.questionName)] == "0.0.0.0" {
} else if dnsMap[parseDomain(question.questionName)] == "0.0.0.0" { // 查表看看是不是拒绝服务的项 回复拒绝服务
rep := refuseDNS(header, question, dnsMap[parseDomain(question.questionName)])
_, writeErr := listener.WriteToUDP(rep, remoteAddr)

Expand All @@ -437,7 +435,7 @@ func main() {
}
return
} else {
rsp := cacheDNS(header, question, dnsMap[parseDomain(question.questionName)])
rsp := cacheDNS(header, question, dnsMap[parseDomain(question.questionName)]) // 表中有且不是 拒绝服务的项 ===> 直接返回 服务器功能
_, writeErr := listener.WriteToUDP(rsp, remoteAddr)

if writeErr != nil {
Expand Down
20 changes: 11 additions & 9 deletions src/main/utils.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,8 +11,9 @@ import (
"strings"
)

const debugEnanled = false
const debugEnanled = false // 控制是否打印调试信息

// 包装debug 快速取消中间log打印
func debug(format string, a ...interface{}) (n int, err error) {
if debugEnanled {
log.Printf("DEBUG:")
Expand All @@ -21,6 +22,7 @@ func debug(format string, a ...interface{}) (n int, err error) {
return
}

// 将ip地址转换为字节的slice
func ipAddrToByte(ipAddr string) []byte {
bits := strings.Split(ipAddr, ".")
b0, _ := strconv.Atoi(bits[0])
Expand All @@ -31,7 +33,7 @@ func ipAddrToByte(ipAddr string) []byte {
return []byte{byte(b0), byte(b1), byte(b2), byte(b3)}
}

//域名解析
// 域名解析
func parseDomain(buf []byte) string {
parts := make([]string, 0)
for i := 0; i < len(buf); {
Expand All @@ -50,7 +52,7 @@ func parseDomain(buf []byte) string {
return strings.Join(parts, ".")
}

//将一个 byte 数组写入另一个 byte 数组
// 将一个 byte 数组写入另一个 byte 数组
func writebytesToBuffer(buffer []byte, buf []byte, n int64) []byte {
for _, b := range buf {
buffer[n] = b
Expand All @@ -59,41 +61,41 @@ func writebytesToBuffer(buffer []byte, buf []byte, n int64) []byte {
return buffer
}

//连接两个 byte 数组，并返回一个新的byte数组
// 连接两个 byte 数组，并返回一个新的byte数组
func linkBytes(b1 []byte, b2 []byte) []byte {
var buf bytes.Buffer
buf.Write(b1)
buf.Write(b2)
return buf.Bytes()
}

//int64转 byte 数组
// int64转 byte 数组
func Int64ToBytes(i int64) []byte {
b_buf := bytes.NewBuffer([]byte{})
binary.Write(b_buf, binary.BigEndian, i)
return b_buf.Bytes()[len(b_buf.Bytes())-2:]
}

//byte 数组转 int64
// byte 数组转 int64
func BytesToInt64(buf []byte) int64 {
bufStr := biu.BytesToBinaryString(buf)
bufint64, _ := strconv.ParseInt(bufStr[len(bufStr)-5:len(bufStr)-1], 10, 64)
return bufint64
}

//字符串转 int64
// 字符串转 int64
func StringToInt64(str string) int64 {
intStr, _ := strconv.ParseInt(str, 10, 64)
return intStr
}

//正则判断字符串是否为 IP
// 正则判断字符串是否为 IP
func isIP(str string) bool {
ipRe := regexp.MustCompile(`^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$`)
return ipRe.MatchString(str)
}

//判断字符串是否为域名
// 判断字符串是否为域名
func isDomain(str string) bool {
domainRe := regexp.MustCompile(`([a-z0-9--]{1,200})\.([a-z]{2,10})(\.[a-z]{2,10})?`)
return domainRe.MatchString(str)
Expand Down

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