Feature: socks5 over unix domain socket(UDS) support

this feature is compatible with tor proxy.

engine/parse.go

@@ -51,11 +51,11 @@ func parseProxy(s string) (proxy.Proxy, error) {
 	case proto.Reject.String():
 		return proxy.NewReject(), nil
 	case proto.HTTP.String():
-		return proxy.NewHTTP(parseAddrUserPass(u))
+		return proxy.NewHTTP(parseHTTP(u))
 	case proto.Socks4.String():
-		return proxy.NewSocks4(parseAddrUser(u))
+		return proxy.NewSocks4(parseSocks4(u))
 	case proto.Socks5.String():
-		return proxy.NewSocks5(parseAddrUserPass(u))
+		return proxy.NewSocks5(parseSocks5(u))
 	case proto.Shadowsocks.String():
 		return proxy.NewShadowsocks(parseShadowsocks(u))
 	default:
@@ -63,14 +63,25 @@ func parseProxy(s string) (proxy.Proxy, error) {
 	}
 }
 
-func parseAddrUser(u *url.URL) (address, username string) {
+func parseHTTP(u *url.URL) (address, username, password string) {
+	address, username = u.Host, u.User.Username()
+	password, _ = u.User.Password()
+	return
+}
+
+func parseSocks4(u *url.URL) (address, username string) {
 	address, username = u.Host, u.User.Username()
 	return
 }
 
-func parseAddrUserPass(u *url.URL) (address, username, password string) {
+func parseSocks5(u *url.URL) (address, username, password string) {
-	address, username = parseAddrUser(u)
+	address, username = u.Host, u.User.Username()
 	password, _ = u.User.Password()
+
+	// Socks5 over UDS
+	if address == "" {
+		address = u.Path
+	}
 	return
 }
 

proxy/socks5.go

@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -19,6 +20,9 @@ type Socks5 struct {
 
 	user string
 	pass string
+
+	// unix indicates if socks5 over UDS is enabled.
+	unix bool
 }
 
 func NewSocks5(addr, user, pass string) (*Socks5, error) {
@@ -29,11 +33,17 @@ func NewSocks5(addr, user, pass string) (*Socks5, error) {
 		},
 		user: user,
 		pass: pass,
+		unix: len(addr) > 0 && addr[0] == '/',
 	}, nil
 }
 
 func (ss *Socks5) DialContext(ctx context.Context, metadata *M.Metadata) (c net.Conn, err error) {
-	c, err = dialer.DialContext(ctx, "tcp", ss.Addr())
+	var network = "tcp"
+	if ss.unix {
+		network = "unix"
+	}
+
+	c, err = dialer.DialContext(ctx, network, ss.Addr())
 	if err != nil {
 		return nil, fmt.Errorf("connect to %s: %w", ss.Addr(), err)
 	}
@@ -54,6 +64,10 @@ func (ss *Socks5) DialContext(ctx context.Context, metadata *M.Metadata) (c net.
 }
 
 func (ss *Socks5) DialUDP(*M.Metadata) (_ net.PacketConn, err error) {
+	if ss.unix {
+		return nil, errors.New("not supported when unix domain socket is enabled")
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), tcpConnectTimeout)
 	defer cancel()