forked from Mxmilu666/frp
146 lines
3.4 KiB
Go
146 lines
3.4 KiB
Go
// Copyright 2023 The frp Authors
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package nathole
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"net"
|
|
"time"
|
|
|
|
"github.com/fatedier/golib/net/stun"
|
|
)
|
|
|
|
var responseTimeout = 3 * time.Second
|
|
|
|
// If the localAddr is empty, it will listen on a random port.
|
|
func Discover(stunServers []string, localAddr string) ([]string, net.Addr, error) {
|
|
discoverConn, err := listen(localAddr)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
defer discoverConn.Close()
|
|
|
|
addresses := make([]string, 0, len(stunServers))
|
|
for _, addr := range stunServers {
|
|
// get external address from stun server
|
|
externalAddrs, err := discoverConn.discoverFromStunServer(addr)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
addresses = append(addresses, externalAddrs...)
|
|
}
|
|
return addresses, discoverConn.localAddr, nil
|
|
}
|
|
|
|
type stunResponse struct {
|
|
externalAddr string
|
|
otherAddr string
|
|
}
|
|
|
|
type discoverConn struct {
|
|
conn *net.UDPConn
|
|
client *stun.Client
|
|
localAddr net.Addr
|
|
}
|
|
|
|
func listen(localAddr string) (*discoverConn, error) {
|
|
var local *net.UDPAddr
|
|
if localAddr != "" {
|
|
addr, err := net.ResolveUDPAddr("udp4", localAddr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
local = addr
|
|
}
|
|
conn, err := net.ListenUDP("udp4", local)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
client, err := stun.NewClient(conn)
|
|
if err != nil {
|
|
_ = conn.Close()
|
|
return nil, err
|
|
}
|
|
|
|
return &discoverConn{
|
|
conn: conn,
|
|
client: client,
|
|
localAddr: conn.LocalAddr(),
|
|
}, nil
|
|
}
|
|
|
|
func (c *discoverConn) Close() error {
|
|
return c.conn.Close()
|
|
}
|
|
|
|
func (c *discoverConn) doSTUNRequest(addr string) (*stunResponse, error) {
|
|
serverAddr, err := net.ResolveUDPAddr("udp4", addr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
transaction, err := stun.NewBindingTransaction(serverAddr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if err := c.conn.SetReadDeadline(time.Now().Add(responseTimeout)); err != nil {
|
|
return nil, err
|
|
}
|
|
response, err := c.client.Do(transaction)
|
|
if err != nil {
|
|
var netErr net.Error
|
|
if errors.As(err, &netErr) && netErr.Timeout() {
|
|
return nil, fmt.Errorf("wait response from stun server timeout")
|
|
}
|
|
return nil, err
|
|
}
|
|
|
|
resp := &stunResponse{}
|
|
if response.MappedAddr != nil {
|
|
resp.externalAddr = response.MappedAddr.String()
|
|
}
|
|
if response.OtherAddr != nil {
|
|
resp.otherAddr = response.OtherAddr.String()
|
|
}
|
|
return resp, nil
|
|
}
|
|
|
|
func (c *discoverConn) discoverFromStunServer(addr string) ([]string, error) {
|
|
resp, err := c.doSTUNRequest(addr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if resp.externalAddr == "" {
|
|
return nil, fmt.Errorf("no external address found")
|
|
}
|
|
|
|
externalAddrs := make([]string, 0, 2)
|
|
externalAddrs = append(externalAddrs, resp.externalAddr)
|
|
|
|
if resp.otherAddr == "" {
|
|
return externalAddrs, nil
|
|
}
|
|
|
|
// find external address from changed address
|
|
resp, err = c.doSTUNRequest(resp.otherAddr)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if resp.externalAddr != "" {
|
|
externalAddrs = append(externalAddrs, resp.externalAddr)
|
|
}
|
|
return externalAddrs, nil
|
|
}
|