174 lines
4.4 KiB
Go
174 lines
4.4 KiB
Go
package socks5
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import (
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"bufio"
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"context"
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"fmt"
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"io/ioutil"
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"log"
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"net"
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)
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// Config is used to setup and configure a Server
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type Config struct {
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// AuthMethods can be provided to implement custom authentication
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// By default, "auth-less" mode is enabled.
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// For password-based auth use UserPassAuthenticator.
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AuthMethods []Authenticator
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// If provided, username/password authentication is enabled,
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// by appending a UserPassAuthenticator to AuthMethods. If not provided,
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// and AUthMethods is nil, then "auth-less" mode is enabled.
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Credentials CredentialStore
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// Resolver can be provided to do custom name resolution.
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// Defaults to DNSResolver if not provided.
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Resolver NameResolver
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// Rules is provided to enable custom logic around permitting
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// various commands. If not provided, PermitAll is used.
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Rules RuleSet
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// Rewriter can be used to transparently rewrite addresses.
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// This is invoked before the RuleSet is invoked.
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// Defaults to NoRewrite.
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Rewriter AddressRewriter
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// BindIP is used for bind or udp associate
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BindIP net.IP
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// Logger can be used to provide a custom log target.
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// Defaults to ioutil.Discard.
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Logger Logger
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// Optional function for dialing out
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Dial func(ctx context.Context, network, addr string) (net.Conn, error)
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}
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// Server is reponsible for accepting connections and handling
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// the details of the SOCKS5 protocol
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type Server struct {
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config *Config
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authMethods map[uint8]Authenticator
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bufferPool *pool
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}
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// New creates a new Server and potentially returns an error
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func New(conf *Config) (*Server, error) {
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// Ensure we have at least one authentication method enabled
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if len(conf.AuthMethods) == 0 {
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if conf.Credentials != nil {
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conf.AuthMethods = []Authenticator{&UserPassAuthenticator{conf.Credentials}}
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} else {
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conf.AuthMethods = []Authenticator{&NoAuthAuthenticator{}}
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}
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}
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// Ensure we have a DNS resolver
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if conf.Resolver == nil {
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conf.Resolver = DNSResolver{}
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}
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// Ensure we have a rule set
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if conf.Rules == nil {
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conf.Rules = PermitAll()
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}
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// Ensure we have a log target
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if conf.Logger == nil {
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conf.Logger = NewLogger(log.New(ioutil.Discard, "socks5: ", log.LstdFlags))
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}
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if conf.Dial == nil {
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conf.Dial = func(ctx context.Context, net_, addr string) (net.Conn, error) {
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return net.Dial(net_, addr)
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}
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}
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server := &Server{
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config: conf,
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bufferPool: newPool(2 * 1024),
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}
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server.authMethods = make(map[uint8]Authenticator)
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for _, a := range conf.AuthMethods {
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server.authMethods[a.GetCode()] = a
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}
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return server, nil
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}
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// ListenAndServe is used to create a listener and serve on it
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func (s *Server) ListenAndServe(network, addr string) error {
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l, err := net.Listen(network, addr)
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if err != nil {
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return err
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}
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return s.Serve(l)
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}
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// Serve is used to serve connections from a listener
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func (s *Server) Serve(l net.Listener) error {
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for {
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conn, err := l.Accept()
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if err != nil {
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return err
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}
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go s.ServeConn(conn)
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}
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}
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// ServeConn is used to serve a single connection.
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func (s *Server) ServeConn(conn net.Conn) (err error) {
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defer conn.Close()
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bufConn := bufio.NewReader(conn)
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// Read the version byte
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version := []byte{0}
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if _, err = bufConn.Read(version); err != nil {
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s.config.Logger.Errorf("failed to get version byte: %v", err)
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return err
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}
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var authContext *AuthContext
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// Ensure we are compatible
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if version[0] == socks5Version {
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// Authenticate the connection
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authContext, err = s.authenticate(conn, bufConn)
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if err != nil {
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err = fmt.Errorf("failed to authenticate: %v", err)
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s.config.Logger.Errorf("%v", err)
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return err
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}
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} else if version[0] != socks4Version {
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err := fmt.Errorf("unsupported SOCKS version: %v", version[0])
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s.config.Logger.Errorf("%v", err)
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return err
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}
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request, err := NewRequest(bufConn)
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if err != nil {
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if err == unrecognizedAddrType {
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if err := sendReply(conn, Header{Version: version[0]}, addrTypeNotSupported); err != nil {
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return fmt.Errorf("failed to send reply, %v", err)
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}
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}
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return fmt.Errorf("failed to read destination address, %v", err)
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}
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if request.Header.Version == socks5Version {
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request.AuthContext = authContext
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}
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if client, ok := conn.RemoteAddr().(*net.TCPAddr); ok {
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request.RemoteAddr = &AddrSpec{IP: client.IP, Port: client.Port}
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}
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// Process the client request
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if err := s.handleRequest(conn, request); err != nil {
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err = fmt.Errorf("failed to handle request, %v", err)
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s.config.Logger.Errorf("%v", err)
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return err
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}
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return nil
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}
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