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fw.go
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fw.go
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package main
import (
"io"
"log"
"net"
"net/http"
"os"
"time"
"io/ioutil"
"encoding/json"
"encoding/base32"
"github.com/dgryski/dgoogauth"
"crypto/rand"
)
type Message struct {
Token string `json:"token"`
}
// List of authenticated IPs
var whitelist = make(map[string]int64)
var otpc *dgoogauth.OTPConfig
func purgelist() {
// Update list
for key := range whitelist {
if whitelist[key] < time.Now().UnixNano() {
delete(whitelist, key)
}
}
}
func authenticate(w http.ResponseWriter, req *http.Request) {
// Read data from request
var u Message
if req.Body == nil {
http.Error(w, "", 404)
return
}
err := json.NewDecoder(req.Body).Decode(&u)
if err != nil {
http.Error(w, "", 404)
return
}
val, err := otpc.Authenticate(u.Token)
if err != nil {
http.Error(w, "", 404)
return
}
if val {
ip, _, _ := net.SplitHostPort(req.RemoteAddr)
whitelist[ip] = time.Now().UnixNano() + 1000000000 * 60 * 60 * 24 * 7
go purgelist()
w.Write([]byte("{\"authenticated\": true}\n"))
} else {
w.Write([]byte("{\"authenticated\": false}\n"))
}
}
func authserv() {
http.HandleFunc("/auth", authenticate)
err := http.ListenAndServeTLS(":8000", "server.crt", "server.key", nil)
if err != nil {
log.Fatal("ListenAndServe: ", err)
}
}
// Forwards connections, even TLS
func forward(conn net.Conn) {
client, err := net.Dial("tcp", os.Args[2])
if err != nil {
log.Println("Error: dial failed: %v", err)
}
// Extract IP and match it
ip, _, _ := net.SplitHostPort(conn.RemoteAddr().String())
registered, ok := whitelist[ip]
if (!ok || registered < time.Now().UnixNano()) {
// Drop connections
client.Close()
conn.Close()
return
}
// Forward data
go func() {
defer client.Close()
defer conn.Close()
io.Copy(client, conn)
}()
go func() {
defer client.Close()
defer conn.Close()
io.Copy(conn, client)
}()
}
func main() {
if len(os.Args) != 3 {
log.Fatalf("Usage %s {from host}:port {to host}:port\n", os.Args[0]);
return
}
data, err := ioutil.ReadFile("token")
var secretBase32 string
if err != nil {
// Generate random secret instead of using the test value above.
secret := make([]byte, 10)
_, err := rand.Read(secret)
if err != nil {
log.Fatalf("Error", err)
}
secretBase32 = base32.StdEncoding.EncodeToString(secret)
data := []byte(secretBase32)
err = ioutil.WriteFile("token", data, 0644)
if err != nil {
log.Fatalf("Error:", err)
}
} else {
secretBase32 = string(data)
}
otpc = &dgoogauth.OTPConfig{
Secret: secretBase32,
WindowSize: 3,
HotpCounter: 0,
// UTC: true,
}
go authserv()
listener, err := net.Listen("tcp", os.Args[1])
if err != nil {
log.Fatalf("Error: failed to setup listener: %v", err)
}
for {
conn, err := listener.Accept()
if err != nil {
log.Fatalf("Error: failed to accept listener: %v", err)
}
go forward(conn)
}
}