421 lines
12 KiB
Go
421 lines
12 KiB
Go
package socks5
|
|
|
|
import (
|
|
"context"
|
|
"fmt"
|
|
"io"
|
|
"net"
|
|
"strings"
|
|
"sync"
|
|
)
|
|
|
|
var (
|
|
errUnrecognizedAddrType = fmt.Errorf("Unrecognized address type")
|
|
)
|
|
|
|
// AddressRewriter is used to rewrite a destination transparently
|
|
type AddressRewriter interface {
|
|
Rewrite(ctx context.Context, request *Request) (context.Context, *AddrSpec)
|
|
}
|
|
|
|
// A Request represents request received by a server
|
|
type Request struct {
|
|
Header
|
|
// AuthContext provided during negotiation
|
|
AuthContext *AuthContext
|
|
// AddrSpec of the the network that sent the request
|
|
RemoteAddr *AddrSpec
|
|
// AddrSpec of the actual destination (might be affected by rewrite)
|
|
DestAddr *AddrSpec
|
|
// Reader connect of request
|
|
Reader io.Reader
|
|
// AddrSpec of the desired destination
|
|
RawDestAddr *AddrSpec
|
|
}
|
|
|
|
type conn interface {
|
|
Write([]byte) (int, error)
|
|
RemoteAddr() net.Addr
|
|
}
|
|
|
|
// NewRequest creates a new Request from the tcp connection
|
|
func NewRequest(bufConn io.Reader) (*Request, error) {
|
|
/*
|
|
The SOCKS request is formed as follows:
|
|
+----+-----+-------+------+----------+----------+
|
|
|VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
|
|
+----+-----+-------+------+----------+----------+
|
|
| 1 | 1 | X'00' | 1 | Variable | 2 |
|
|
+----+-----+-------+------+----------+----------+
|
|
*/
|
|
hd, err := Parse(bufConn)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if hd.Command != CommandConnect && hd.Command != CommandBind && hd.Command != CommandAssociate {
|
|
return nil, fmt.Errorf("unrecognized command[%d]", hd.Command)
|
|
}
|
|
return &Request{
|
|
Header: hd,
|
|
RawDestAddr: &hd.Address,
|
|
Reader: bufConn,
|
|
}, nil
|
|
}
|
|
|
|
// handleRequest is used for request processing after authentication
|
|
func (s *Server) handleRequest(write io.Writer, req *Request) error {
|
|
ctx := context.Background()
|
|
|
|
// Resolve the address if we have a FQDN
|
|
dest := req.RawDestAddr
|
|
if dest.FQDN != "" {
|
|
_ctx, addr, err := s.resolver.Resolve(ctx, dest.FQDN)
|
|
if err != nil {
|
|
if err := SendReply(write, req.Header, RepHostUnreachable); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("failed to resolve destination[%v], %v", dest.FQDN, err)
|
|
}
|
|
ctx = _ctx
|
|
dest.IP = addr
|
|
}
|
|
|
|
// Apply any address rewrites
|
|
req.DestAddr = req.RawDestAddr
|
|
if s.rewriter != nil {
|
|
ctx, req.DestAddr = s.rewriter.Rewrite(ctx, req)
|
|
}
|
|
|
|
// Check if this is allowed
|
|
_ctx, ok := s.rules.Allow(ctx, req)
|
|
if !ok {
|
|
if err := SendReply(write, req.Header, RepRuleFailure); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("bind to %v blocked by rules", req.RawDestAddr)
|
|
}
|
|
ctx = _ctx
|
|
|
|
// Switch on the command
|
|
switch req.Command {
|
|
case CommandConnect:
|
|
if s.userConnectHandle != nil {
|
|
return s.userConnectHandle(ctx, write, req)
|
|
}
|
|
return s.handleConnect(ctx, write, req)
|
|
case CommandBind:
|
|
if s.userBindHandle != nil {
|
|
return s.userBindHandle(ctx, write, req)
|
|
}
|
|
return s.handleBind(ctx, write, req)
|
|
case CommandAssociate:
|
|
if s.userAssociateHandle != nil {
|
|
return s.userAssociateHandle(ctx, write, req)
|
|
}
|
|
return s.handleAssociate(ctx, write, req)
|
|
default:
|
|
if err := SendReply(write, req.Header, RepCommandNotSupported); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("unsupported command[%v]", req.Command)
|
|
}
|
|
}
|
|
|
|
// handleConnect is used to handle a connect command
|
|
func (s *Server) handleConnect(ctx context.Context, writer io.Writer, req *Request) error {
|
|
// Attempt to connect
|
|
dial := s.dial
|
|
if dial == nil {
|
|
dial = func(ctx context.Context, net_, addr string) (net.Conn, error) {
|
|
return net.Dial(net_, addr)
|
|
}
|
|
}
|
|
target, err := dial(ctx, "tcp", req.DestAddr.Address())
|
|
if err != nil {
|
|
msg := err.Error()
|
|
resp := RepHostUnreachable
|
|
if strings.Contains(msg, "refused") {
|
|
resp = RepConnectionRefused
|
|
} else if strings.Contains(msg, "network is unreachable") {
|
|
resp = RepNetworkUnreachable
|
|
}
|
|
if err := SendReply(writer, req.Header, resp); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("connect to %v failed, %v", req.RawDestAddr, err)
|
|
}
|
|
defer target.Close()
|
|
|
|
// Send success
|
|
if err := SendReply(writer, req.Header, RepSuccess, target.LocalAddr()); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
|
|
// Start proxying
|
|
errCh := make(chan error, 2)
|
|
|
|
s.submit(func() { errCh <- s.Proxy(target, req.Reader) })
|
|
s.submit(func() { errCh <- s.Proxy(writer, target) })
|
|
|
|
// Wait
|
|
for i := 0; i < 2; i++ {
|
|
e := <-errCh
|
|
if e != nil {
|
|
// return from this function closes target (and conn).
|
|
return e
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// handleBind is used to handle a connect command
|
|
func (s *Server) handleBind(_ context.Context, writer io.Writer, req *Request) error {
|
|
// TODO: Support bind
|
|
if err := SendReply(writer, req.Header, RepCommandNotSupported); err != nil {
|
|
return fmt.Errorf("failed to send reply: %v", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// handleAssociate is used to handle a connect command
|
|
func (s *Server) handleAssociate(ctx context.Context, writer io.Writer, req *Request) error {
|
|
// Attempt to connect
|
|
dial := s.dial
|
|
if dial == nil {
|
|
dial = func(ctx context.Context, net_, addr string) (net.Conn, error) {
|
|
return net.Dial(net_, addr)
|
|
}
|
|
}
|
|
target, err := dial(ctx, "udp", req.DestAddr.Address())
|
|
if err != nil {
|
|
msg := err.Error()
|
|
resp := RepHostUnreachable
|
|
if strings.Contains(msg, "refused") {
|
|
resp = RepConnectionRefused
|
|
} else if strings.Contains(msg, "network is unreachable") {
|
|
resp = RepNetworkUnreachable
|
|
}
|
|
if err := SendReply(writer, req.Header, resp); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("connect to %v failed, %v", req.RawDestAddr, err)
|
|
}
|
|
defer target.Close()
|
|
|
|
targetUDP, ok := target.(*net.UDPConn)
|
|
if !ok {
|
|
if err := SendReply(writer, req.Header, RepServerFailure); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("dial udp invalid")
|
|
}
|
|
|
|
bindLn, err := net.ListenUDP("udp", nil)
|
|
if err != nil {
|
|
if err := SendReply(writer, req.Header, RepServerFailure); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
return fmt.Errorf("listen udp failed, %v", err)
|
|
}
|
|
defer bindLn.Close()
|
|
|
|
s.logger.Errorf("target addr %v, listen addr: %s", targetUDP.RemoteAddr(), bindLn.LocalAddr())
|
|
// send BND.ADDR and BND.PORT, client must
|
|
if err = SendReply(writer, req.Header, RepSuccess, bindLn.LocalAddr()); err != nil {
|
|
return fmt.Errorf("failed to send reply, %v", err)
|
|
}
|
|
|
|
s.submit(func() {
|
|
/*
|
|
The SOCKS UDP request/response is formed as follows:
|
|
+-----+------+-------+----------+----------+----------+
|
|
| RSV | FRAG | ATYP | DST.ADDR | DST.PORT | DATA |
|
|
+-----+------+-------+----------+----------+----------+
|
|
| 2 | 1 | X'00' | Variable | 2 | Variable |
|
|
+-----+------+-------+----------+----------+----------+
|
|
*/
|
|
// read from client and write to remote server
|
|
conns := sync.Map{}
|
|
bufPool := s.bufferPool.Get()
|
|
defer func() {
|
|
targetUDP.Close()
|
|
bindLn.Close()
|
|
s.bufferPool.Put(bufPool)
|
|
}()
|
|
for {
|
|
buf := bufPool[:cap(bufPool)]
|
|
n, srcAddr, err := bindLn.ReadFrom(buf)
|
|
if err != nil {
|
|
s.logger.Errorf("read data from bind listen address %s failed, %v", bindLn.LocalAddr(), err)
|
|
return
|
|
}
|
|
|
|
if n <= 4+net.IPv4len+2 { // no data
|
|
continue
|
|
}
|
|
// ignore RSV,FRAG
|
|
addrType := buf[3]
|
|
addrLen := 0
|
|
headLen := 0
|
|
var addrSpc AddrSpec
|
|
if addrType == ATYPIPv4 {
|
|
headLen = 4 + net.IPv4len + 2
|
|
addrLen = net.IPv4len
|
|
addrSpc.IP = make(net.IP, net.IPv4len)
|
|
copy(addrSpc.IP, buf[4:4+net.IPv4len])
|
|
addrSpc.Port = buildPort(buf[4+net.IPv4len], buf[4+net.IPv4len+1])
|
|
} else if addrType == ATYPIPV6 {
|
|
headLen = 4 + net.IPv6len + 2
|
|
if n <= headLen {
|
|
continue
|
|
}
|
|
addrLen = net.IPv6len
|
|
addrSpc.IP = make(net.IP, net.IPv6len)
|
|
copy(addrSpc.IP, buf[4:4+net.IPv6len])
|
|
addrSpc.Port = buildPort(buf[4+net.IPv6len], buf[4+net.IPv6len+1])
|
|
} else if addrType == ATYPDomain {
|
|
addrLen = int(buf[4])
|
|
headLen = 4 + 1 + addrLen + 2
|
|
if n <= headLen {
|
|
continue
|
|
}
|
|
str := make([]byte, addrLen)
|
|
copy(str, buf[5:5+addrLen])
|
|
addrSpc.FQDN = string(str)
|
|
addrSpc.Port = buildPort(buf[5+addrLen], buf[5+addrLen+1])
|
|
} else {
|
|
continue
|
|
}
|
|
|
|
// 把消息写给remote sever
|
|
if _, err := targetUDP.Write(buf[headLen:n]); err != nil {
|
|
s.logger.Errorf("write data to remote %s failed, %v", targetUDP.RemoteAddr(), err)
|
|
return
|
|
}
|
|
|
|
if _, ok := conns.LoadOrStore(srcAddr.String(), struct{}{}); !ok {
|
|
s.submit(func() {
|
|
// read from remote server and write to client
|
|
bufPool := s.bufferPool.Get()
|
|
defer func() {
|
|
targetUDP.Close()
|
|
bindLn.Close()
|
|
s.bufferPool.Put(bufPool)
|
|
}()
|
|
|
|
for {
|
|
buf := bufPool[:cap(bufPool)]
|
|
n, remote, err := targetUDP.ReadFrom(buf)
|
|
if err != nil {
|
|
s.logger.Errorf("read data from remote %s failed, %v", targetUDP.RemoteAddr(), err)
|
|
return
|
|
}
|
|
|
|
tmpBufPool := s.bufferPool.Get()
|
|
proBuf := tmpBufPool
|
|
rAddr, _ := net.ResolveUDPAddr("udp", remote.String())
|
|
hi, lo := breakPort(rAddr.Port)
|
|
if rAddr.IP.To4() != nil {
|
|
proBuf = append(proBuf, []byte{0, 0, 0, ATYPIPv4}...)
|
|
proBuf = append(proBuf, rAddr.IP.To4()...)
|
|
proBuf = append(proBuf, hi, lo)
|
|
} else if rAddr.IP.To16() != nil {
|
|
proBuf = append(proBuf, []byte{0, 0, 0, ATYPIPV6}...)
|
|
proBuf = append(proBuf, rAddr.IP.To16()...)
|
|
proBuf = append(proBuf, hi, lo)
|
|
} else { // should never happen
|
|
continue
|
|
}
|
|
proBuf = append(proBuf, buf[:n]...)
|
|
if _, err := bindLn.WriteTo(proBuf, srcAddr); err != nil {
|
|
s.bufferPool.Put(tmpBufPool)
|
|
s.logger.Errorf("write data to client %s failed, %v", bindLn.LocalAddr(), err)
|
|
return
|
|
}
|
|
s.bufferPool.Put(tmpBufPool)
|
|
}
|
|
})
|
|
}
|
|
}
|
|
})
|
|
|
|
buf := s.bufferPool.Get()
|
|
defer func() {
|
|
s.bufferPool.Put(buf)
|
|
}()
|
|
for {
|
|
_, err := req.Reader.Read(buf[:cap(buf)])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
}
|
|
|
|
// SendReply is used to send a reply message
|
|
func SendReply(w io.Writer, head Header, resp uint8, bindAddr ...net.Addr) error {
|
|
/*
|
|
The SOCKS response is formed as follows:
|
|
+----+-----+-------+------+----------+----------+
|
|
|VER | CMD | RSV | ATYP | BND.ADDR | BND.PORT |
|
|
+----+-----+-------+------+----------+----------+
|
|
| 1 | 1 | X'00' | 1 | Variable | 2 |
|
|
+----+-----+-------+------+----------+----------+
|
|
*/
|
|
|
|
head.Command = resp
|
|
|
|
if len(bindAddr) == 0 {
|
|
head.addrType = ATYPIPv4
|
|
head.Address.IP = []byte{0, 0, 0, 0}
|
|
head.Address.Port = 0
|
|
} else {
|
|
addrSpec := AddrSpec{}
|
|
if tcpAddr, ok := bindAddr[0].(*net.TCPAddr); ok && tcpAddr != nil {
|
|
addrSpec.IP = tcpAddr.IP
|
|
addrSpec.Port = tcpAddr.Port
|
|
} else if udpAddr, ok := bindAddr[0].(*net.UDPAddr); ok && udpAddr != nil {
|
|
addrSpec.IP = udpAddr.IP
|
|
addrSpec.Port = udpAddr.Port
|
|
} else {
|
|
addrSpec.IP = []byte{0, 0, 0, 0}
|
|
addrSpec.Port = 0
|
|
}
|
|
switch {
|
|
case addrSpec.FQDN != "":
|
|
head.addrType = ATYPDomain
|
|
head.Address.FQDN = addrSpec.FQDN
|
|
head.Address.Port = addrSpec.Port
|
|
case addrSpec.IP.To4() != nil:
|
|
head.addrType = ATYPIPv4
|
|
head.Address.IP = addrSpec.IP.To4()
|
|
head.Address.Port = addrSpec.Port
|
|
case addrSpec.IP.To16() != nil:
|
|
head.addrType = ATYPIPV6
|
|
head.Address.IP = addrSpec.IP.To16()
|
|
head.Address.Port = addrSpec.Port
|
|
default:
|
|
return fmt.Errorf("failed to format address[%v]", bindAddr)
|
|
}
|
|
|
|
}
|
|
// Send the message
|
|
_, err := w.Write(head.Bytes())
|
|
return err
|
|
}
|
|
|
|
type closeWriter interface {
|
|
CloseWrite() error
|
|
}
|
|
|
|
// Proxy is used to suffle data from src to destination, and sends errors
|
|
// down a dedicated channel
|
|
func (s *Server) Proxy(dst io.Writer, src io.Reader) error {
|
|
buf := s.bufferPool.Get()
|
|
defer s.bufferPool.Put(buf)
|
|
_, err := io.CopyBuffer(dst, src, buf[:cap(buf)])
|
|
if tcpConn, ok := dst.(closeWriter); ok {
|
|
tcpConn.CloseWrite()
|
|
}
|
|
return err
|
|
}
|