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dns.go
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dns.go
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// dns.go
package main
import (
"bytes"
"fmt"
"log"
"net"
"strings"
"time"
)
func dns_tcpOverUdp(cConn *net.TCPConn, host string, buffer []byte) {
log.Println("Start dns_tcpOverUdp")
defer cConn.Close()
var err error
var WLen, RLen, payloadLen, CuteBi_XorCrypt_passwordSub int
var pkgLen uint16
for {
//cConn.SetReadDeadline(time.Now().Add(tcp_timeout))
RLen, err = cConn.Read(buffer[payloadLen:])
if RLen <= 0 || err != nil {
return
}
//解密
if len(CuteBi_XorCrypt_password) != 0 {
CuteBi_XorCrypt_passwordSub = CuteBi_XorCrypt(buffer[payloadLen:payloadLen+RLen], CuteBi_XorCrypt_passwordSub)
}
payloadLen += RLen
if payloadLen > 2 {
pkgLen = (uint16(buffer[0]) << 8) | (uint16(buffer[1])) //包长度转换
//防止访问非法数据
if int(pkgLen)+2 > len(buffer) {
return
}
//如果读取到了一个完整的包，就跳出循环
if int(pkgLen)+2 <= payloadLen {
break
}
}
}
/* 连接目标地址 */
sConn, dialErr := net.Dial("udp", host)
if dialErr != nil {
log.Println(dialErr)
cConn.Write([]byte("Proxy address [" + host + "] DNS Dial() error"))
return
}
defer sConn.Close()
if WLen, err = sConn.Write(buffer[2:payloadLen]); WLen <= 0 || err != nil {
return
}
sConn.SetReadDeadline(time.Now().Add(udp_timeout))
if RLen, err = sConn.Read(buffer[2:]); RLen <= 0 || err != nil {
return
}
//包长度转换
buffer[0] = byte(RLen >> 8)
buffer[1] = byte(RLen)
//加密
if len(CuteBi_XorCrypt_password) != 0 {
CuteBi_XorCrypt(buffer[:2+RLen], 0)
}
cConn.Write(buffer[:2+RLen])
}
func RespondHttpdns(cConn *net.TCPConn, header []byte) bool {
var domain string
httpdnsDomainsub := bytes.Index(header[:], []byte("?dn="))
if httpdnsDomainsub < 0 {
return false
}
if _, err := fmt.Sscanf(string(header[httpdnsDomainsub+4:]), "%s", &domain); err != nil {
log.Println(err)
return false
}
log.Println("httpDNS domain: [" + domain + "]")
ips, err := net.LookupHost(domain)
if err != nil {
cConn.Write([]byte("HTTP/1.0 404 Not Found\r\nConnection: Close\r\nServer: CuteBi Linux Network httpDNS, (%>w<%)\r\nContent-type: charset=utf-8\r\n\r\n<html><head><title>HTTP DNS Server</title></head><body>查询域名失败<br/><br/>By: 萌萌萌得不要不要哒<br/>E-mail: [email protected]</body></html>"))
log.Println("httpDNS domain: [" + domain + "], Lookup failed")
} else {
for i := 0; i < len(ips); i++ {
if !strings.Contains(ips[i], ":") { //跳过ipv6
fmt.Fprintf(cConn, "HTTP/1.0 200 OK\r\nConnection: Close\r\nServer: CuteBi Linux Network httpDNS, (%%>w<%%)\r\nContent-Length: %d\r\n\r\n%s", len(string(ips[i])), string(ips[i]))
break
}
}
log.Println("httpDNS domain: ["+domain+"], IPS: ", ips)
}
cConn.Close()
return true
}