frp/vendor/github.com/armon/go-socks5/socks5.go

170 lines
4.2 KiB
Go

package socks5
import (
"bufio"
"fmt"
"log"
"net"
"os"
"golang.org/x/net/context"
)
const (
socks5Version = uint8(5)
)
// Config is used to setup and configure a Server
type Config struct {
// AuthMethods can be provided to implement custom authentication
// By default, "auth-less" mode is enabled.
// For password-based auth use UserPassAuthenticator.
AuthMethods []Authenticator
// If provided, username/password authentication is enabled,
// by appending a UserPassAuthenticator to AuthMethods. If not provided,
// and AUthMethods is nil, then "auth-less" mode is enabled.
Credentials CredentialStore
// Resolver can be provided to do custom name resolution.
// Defaults to DNSResolver if not provided.
Resolver NameResolver
// Rules is provided to enable custom logic around permitting
// various commands. If not provided, PermitAll is used.
Rules RuleSet
// Rewriter can be used to transparently rewrite addresses.
// This is invoked before the RuleSet is invoked.
// Defaults to NoRewrite.
Rewriter AddressRewriter
// BindIP is used for bind or udp associate
BindIP net.IP
// Logger can be used to provide a custom log target.
// Defaults to stdout.
Logger *log.Logger
// Optional function for dialing out
Dial func(ctx context.Context, network, addr string) (net.Conn, error)
}
// Server is reponsible for accepting connections and handling
// the details of the SOCKS5 protocol
type Server struct {
config *Config
authMethods map[uint8]Authenticator
}
// New creates a new Server and potentially returns an error
func New(conf *Config) (*Server, error) {
// Ensure we have at least one authentication method enabled
if len(conf.AuthMethods) == 0 {
if conf.Credentials != nil {
conf.AuthMethods = []Authenticator{&UserPassAuthenticator{conf.Credentials}}
} else {
conf.AuthMethods = []Authenticator{&NoAuthAuthenticator{}}
}
}
// Ensure we have a DNS resolver
if conf.Resolver == nil {
conf.Resolver = DNSResolver{}
}
// Ensure we have a rule set
if conf.Rules == nil {
conf.Rules = PermitAll()
}
// Ensure we have a log target
if conf.Logger == nil {
conf.Logger = log.New(os.Stdout, "", log.LstdFlags)
}
server := &Server{
config: conf,
}
server.authMethods = make(map[uint8]Authenticator)
for _, a := range conf.AuthMethods {
server.authMethods[a.GetCode()] = a
}
return server, nil
}
// ListenAndServe is used to create a listener and serve on it
func (s *Server) ListenAndServe(network, addr string) error {
l, err := net.Listen(network, addr)
if err != nil {
return err
}
return s.Serve(l)
}
// Serve is used to serve connections from a listener
func (s *Server) Serve(l net.Listener) error {
for {
conn, err := l.Accept()
if err != nil {
return err
}
go s.ServeConn(conn)
}
return nil
}
// ServeConn is used to serve a single connection.
func (s *Server) ServeConn(conn net.Conn) error {
defer conn.Close()
bufConn := bufio.NewReader(conn)
// Read the version byte
version := []byte{0}
if _, err := bufConn.Read(version); err != nil {
s.config.Logger.Printf("[ERR] socks: Failed to get version byte: %v", err)
return err
}
// Ensure we are compatible
if version[0] != socks5Version {
err := fmt.Errorf("Unsupported SOCKS version: %v", version)
s.config.Logger.Printf("[ERR] socks: %v", err)
return err
}
// Authenticate the connection
authContext, err := s.authenticate(conn, bufConn)
if err != nil {
err = fmt.Errorf("Failed to authenticate: %v", err)
s.config.Logger.Printf("[ERR] socks: %v", err)
return err
}
request, err := NewRequest(bufConn)
if err != nil {
if err == unrecognizedAddrType {
if err := sendReply(conn, addrTypeNotSupported, nil); err != nil {
return fmt.Errorf("Failed to send reply: %v", err)
}
}
return fmt.Errorf("Failed to read destination address: %v", err)
}
request.AuthContext = authContext
if client, ok := conn.RemoteAddr().(*net.TCPAddr); ok {
request.RemoteAddr = &AddrSpec{IP: client.IP, Port: client.Port}
}
// Process the client request
if err := s.handleRequest(request, conn); err != nil {
err = fmt.Errorf("Failed to handle request: %v", err)
s.config.Logger.Printf("[ERR] socks: %v", err)
return err
}
return nil
}