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net.go
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net.go
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package helper
import (
"bufio"
"errors"
"fmt"
"log"
"math"
"net"
"net/http"
"net/url"
"strconv"
"strings"
"time"
"github.com/getlantern/netx"
)
var ErrTLSIncomplete = errors.New("TLS header incomplete")
var ErrNoSNI = errors.New("No SNI in protocol")
var ErrTLSClientHello = errors.New("Invalid tls client hello")
func TLSReplaceSNI(data []byte, sni string) ([]byte, string, error) {
name, offset, err := tlsParseSNI(data)
if nil == err {
newData := make([]byte, offset)
copy(newData, data[0:offset])
//newData := data[0:offset]
tailData := data[offset+2+len(name):]
sniData := make([]byte, 2+len(sni))
sniData[0] = uint8(uint16(len(sni)) >> 8)
sniData[1] = uint8(uint16(len(sni)) & 0xFF)
copy(sniData[2:], []byte(sni))
newData = append(newData, sniData...)
newData = append(newData, tailData...)
if name == sni {
return data, name, nil
}
return newData, name, nil
}
return data, name, err
}
func TLSParseSNI(data []byte) (string, error) {
name, _, err := tlsParseSNI(data)
return name, err
}
func tlsParseSNI(data []byte) (string, int, error) {
tlsHederLen := 5
if len(data) < tlsHederLen {
return "", 0, ErrTLSIncomplete
}
if (int(data[0])&0x80) != 0 && data[2] == 1 {
return "", 0, ErrNoSNI
}
tlsContentType := int(data[0])
if tlsContentType != 0x16 {
log.Printf("Invaid content type:%d with %v", tlsContentType, ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
tlsMajorVer := int(data[1])
tlsMinorVer := int(data[2])
if tlsMajorVer < 3 {
log.Printf("Invaid tls ver:%d with %v", tlsMajorVer, ErrNoSNI)
return "", 0, ErrNoSNI
}
tlsLen := (int(data[3]) << 8) + int(data[4]) + tlsHederLen
if tlsLen > len(data) {
return "", 0, ErrTLSIncomplete
}
//log.Printf("####TLS %d %d", tlsLen, len(data))
pos := tlsHederLen
if pos+1 > len(data) {
log.Printf("Less data 1 %v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
tlsHandshakeTypeClientHello := 0x01
if int(data[pos]) != tlsHandshakeTypeClientHello {
log.Printf("Not client hello type:%d with err:%v", data[pos], ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
/* Skip past fixed length records:
1 Handshake Type
3 Length
2 Version (again)
32 Random
to Session ID Length
*/
pos += 38
if pos+1 > len(data) {
log.Printf("Less data 2 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
nextLen := int(data[pos])
pos = pos + 1 + nextLen
if pos+2 > len(data) {
log.Printf("Less data 3 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
nextLen = (int(data[pos]) << 8) + int(data[pos+1])
pos = pos + 2 + nextLen
if pos+1 > len(data) {
log.Printf("Less data 4 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
nextLen = int(data[pos])
pos = pos + 1 + nextLen
if pos == len(data) && tlsMajorVer == 3 && tlsMinorVer == 0 {
log.Printf("No sni in 3.0 %v", ErrNoSNI)
return "", 0, ErrNoSNI
}
if pos+2 > len(data) {
log.Printf("Less data 5 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
nextLen = (int(data[pos]) << 8) + int(data[pos+1])
pos += 2
if pos+nextLen > len(data) {
log.Printf("Less data 6 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
return parseExtension(data[pos:], pos)
}
func parseExtension(data []byte, offset int) (string, int, error) {
pos := 0
for (pos + 4) <= len(data) {
nextLen := (int(data[pos+2]) << 8) + int(data[pos+3])
if int(data[pos]) == 0x00 && int(data[pos+1]) == 0x00 {
if pos+4+nextLen > len(data) {
log.Printf("Less data 7 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
offset = offset + pos + 4
return parseServerNameExtension(data[pos+4:], offset)
}
pos = pos + 4 + nextLen
}
if pos != len(data) {
log.Printf("Less data 8 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
return "", 0, ErrNoSNI
}
func parseServerNameExtension(data []byte, offset int) (string, int, error) {
pos := 2
for pos+3 < len(data) {
nextLen := (int(data[pos+1]) << 8) + int(data[pos+2])
if pos+3+nextLen > len(data) {
log.Printf("Less data 9 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
if int(data[pos]) == 0x00 {
offset = offset + pos + 1
name := make([]byte, nextLen)
copy(name, data[pos+3:])
return string(name), offset, nil
}
pos = pos + 3 + nextLen
}
if pos != len(data) {
log.Printf("Less data 10 with err:%v", ErrTLSClientHello)
return "", 0, ErrTLSClientHello
}
return "", 0, ErrNoSNI
}
func Long2IPv4(i uint64) string {
return fmt.Sprintf("%d.%d.%d.%d", (i>>24)&0xFF, (i>>16)&0xFF, (i>>8)&0xFF, i&0xFF)
}
func IPv42Int(ip string) (int64, error) {
addrArray := strings.Split(ip, ".")
var num int64
num = 0
for i := 0; i < len(addrArray); i++ {
power := 3 - i
if v, err := strconv.Atoi(addrArray[i]); nil != err {
return -1, err
} else {
num += (int64(v) % 256 * int64(math.Pow(float64(256), float64(power))))
}
}
return num, nil
}
func IsPrivateIP(ip string) bool {
if strings.EqualFold(ip, "localhost") {
return true
}
value, err := IPv42Int(ip)
if nil != err {
return false
}
if strings.HasPrefix(ip, "127.0") {
return true
}
if (value >= 0x0A000000 && value <= 0x0AFFFFFF) || (value >= 0xAC100000 && value <= 0xAC1FFFFF) || (value >= 0xC0A80000 && value <= 0xC0A8FFFF) {
return true
}
return false
}
func HTTPProxyConn(proxyURL string, addr string, timeout time.Duration) (net.Conn, error) {
u, err := url.Parse(proxyURL)
if nil != err {
return nil, err
}
c, err := netx.DialTimeout("tcp", u.Host, timeout)
if err != nil {
return nil, err
}
connReq, _ := http.NewRequest("Connect", addr, nil)
err = connReq.Write(c)
if err != nil {
return nil, err
}
connRes, err := http.ReadResponse(bufio.NewReader(c), connReq)
if err != nil {
return nil, err
}
if nil != connRes.Body {
connRes.Body.Close()
}
if connRes.StatusCode >= 300 {
return nil, fmt.Errorf("Invalid Connect response:%d", connRes.StatusCode)
}
return c, nil
}
var localIPv4 []string
func GetLocalIPv4() []string {
if len(localIPv4) > 0 {
return localIPv4
}
addrs, err := net.InterfaceAddrs()
if err != nil {
log.Printf("[ERROR]Failed to get local ip:%v", err)
return localIPv4
}
for _, a := range addrs {
if ipnet, ok := a.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
if ipnet.IP.To4() != nil {
localIPv4 = append(localIPv4, ipnet.IP.String())
}
}
}
return localIPv4
}