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server.go
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server.go
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package socks
import (
"bytes"
"context"
"errors"
"fmt"
"io"
"io/ioutil"
"net"
"sync"
"time"
"github.com/xxf098/lite-proxy/common"
"github.com/xxf098/lite-proxy/log"
"github.com/xxf098/lite-proxy/tunnel"
)
const (
Connect tunnel.Command = 1
Associate tunnel.Command = 3
MaxPacketSize = 1024 * 8
)
type Server struct {
connChan chan tunnel.Conn
packetChan chan tunnel.PacketConn
underlay tunnel.Server
localHost string
localPort int
timeout time.Duration
listenPacketConn net.PacketConn
mapping map[string]*PacketConn
mappingLock sync.RWMutex
ctx context.Context
cancel context.CancelFunc
}
func (s *Server) AcceptConn(tunnel.Tunnel) (tunnel.Conn, error) {
select {
case conn := <-s.connChan:
return conn, nil
case <-s.ctx.Done():
return nil, errors.New("socks server closed")
}
}
func (s *Server) AcceptPacket(tunnel.Tunnel) (tunnel.PacketConn, error) {
select {
case conn := <-s.packetChan:
return conn, nil
case <-s.ctx.Done():
return nil, common.NewError("socks server closed")
}
}
func (s *Server) Close() error {
s.cancel()
return s.underlay.Close()
}
func (s *Server) handshake(conn net.Conn) (*Conn, error) {
version := [1]byte{}
if _, err := conn.Read(version[:]); err != nil {
return nil, common.NewError("failed to read socks version").Base(err)
}
if version[0] != 5 {
return nil, common.NewError(fmt.Sprintf("invalid socks version %d", version[0]))
}
nmethods := [1]byte{}
if _, err := conn.Read(nmethods[:]); err != nil {
return nil, common.NewError("failed to read NMETHODS")
}
if _, err := io.CopyN(ioutil.Discard, conn, int64(nmethods[0])); err != nil {
return nil, common.NewError("socks failed to read methods").Base(err)
}
if _, err := conn.Write([]byte{0x5, 0x0}); err != nil {
return nil, common.NewError("failed to respond auth").Base(err)
}
buf := [3]byte{}
if _, err := conn.Read(buf[:]); err != nil {
return nil, common.NewError("failed to read command")
}
addr := new(tunnel.Address)
if err := addr.ReadFrom(conn); err != nil {
return nil, err
}
return &Conn{
metadata: &tunnel.Metadata{
Command: tunnel.Command(buf[1]),
Address: addr,
},
Conn: conn,
}, nil
}
func (s *Server) connect(conn net.Conn) error {
_, err := conn.Write([]byte{0x05, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00})
return err
}
func (s *Server) associate(conn net.Conn, addr *tunnel.Address) error {
buf := bytes.NewBuffer([]byte{0x05, 0x00, 0x00})
common.Must(addr.WriteTo(buf))
_, err := conn.Write(buf.Bytes())
return err
}
func (s *Server) packetDispatchLoop() {
for {
buf := make([]byte, MaxPacketSize)
n, src, err := s.listenPacketConn.ReadFrom(buf)
if err != nil {
select {
case <-s.ctx.Done():
log.D("exiting")
return
default:
continue
}
}
log.D("socks recv udp packet from", src)
s.mappingLock.RLock()
conn, found := s.mapping[src.String()]
s.mappingLock.RUnlock()
if !found {
ctx, cancel := context.WithCancel(s.ctx)
conn = &PacketConn{
input: make(chan *packetInfo, 128),
output: make(chan *packetInfo, 128),
ctx: ctx,
cancel: cancel,
PacketConn: s.listenPacketConn,
src: src,
}
go func(conn *PacketConn) {
defer conn.Close()
for {
select {
case info := <-conn.output:
buf := bytes.NewBuffer(make([]byte, 0, MaxPacketSize))
buf.Write([]byte{0, 0, 0}) //RSV, FRAG
common.Must(info.metadata.Address.WriteTo(buf))
buf.Write(info.payload)
_, err := s.listenPacketConn.WriteTo(buf.Bytes(), conn.src)
if err != nil {
log.E("socks failed to respond packet to", src)
return
}
log.D("socks respond udp packet to", src, "metadata", info.metadata)
case <-time.After(time.Second * 5):
log.I("socks udp session timeout, closed")
s.mappingLock.Lock()
delete(s.mapping, src.String())
s.mappingLock.Unlock()
return
case <-conn.ctx.Done():
log.I("socks udp session closed")
return
}
}
}(conn)
s.mappingLock.Lock()
s.mapping[src.String()] = conn
s.mappingLock.Unlock()
s.packetChan <- conn
log.I("socks new udp session from", src)
}
r := bytes.NewBuffer(buf[3:n])
address := new(tunnel.Address)
if err := address.ReadFrom(r); err != nil {
log.Error(common.NewError("socks failed to parse incoming packet").Base(err))
continue
}
payload := make([]byte, MaxPacketSize)
length, err := r.Read(payload)
select {
case conn.input <- &packetInfo{
metadata: &tunnel.Metadata{
Address: address,
},
payload: payload[:length],
}:
default:
log.W("socks udp queue full")
}
}
}
func (s *Server) acceptLoop() {
for {
conn, err := s.underlay.AcceptConn(&Tunnel{})
if err != nil {
log.Error(common.NewError("socks accept err").Base(err))
return
}
go func(conn net.Conn) {
newConn, err := s.handshake(conn)
if err != nil {
log.Error(common.NewError("socks failed to handshake with client").Base(err))
return
}
log.I("socks connection from", conn.RemoteAddr(), "metadata", newConn.metadata.String())
switch newConn.metadata.Command {
case Connect:
if err := s.connect(newConn); err != nil {
log.Error(common.NewError("socks failed to respond CONNECT").Base(err))
newConn.Close()
return
}
s.connChan <- newConn
return
case Associate:
defer newConn.Close()
associateAddr := tunnel.NewAddressFromHostPort("udp", s.localHost, s.localPort)
if err := s.associate(newConn, associateAddr); err != nil {
log.Error(common.NewError("socks failed to respond to associate request").Base(err))
return
}
buf := [16]byte{}
newConn.Read(buf[:])
log.D("socks udp session ends")
default:
log.Error(common.NewError(fmt.Sprintf("unknown socks command %d", newConn.metadata.Command)))
newConn.Close()
}
}(conn)
}
}
func NewServer(ctx context.Context, underlay tunnel.Server) (*Server, error) {
listenPacketConn, err := underlay.AcceptPacket(&Tunnel{})
if err != nil {
return nil, err
}
localHost := ctx.Value("LocalHost").(string)
localPort := ctx.Value("LocalPort").(int)
ctx, cancel := context.WithCancel(ctx)
server := &Server{
underlay: underlay,
ctx: ctx,
cancel: cancel,
connChan: make(chan tunnel.Conn, 32),
packetChan: make(chan tunnel.PacketConn, 32),
localHost: localHost,
localPort: localPort,
timeout: 5 * time.Second,
listenPacketConn: listenPacketConn,
mapping: make(map[string]*PacketConn),
}
go server.acceptLoop()
go server.packetDispatchLoop()
log.D("socks server created", localPort)
return server, nil
}