feat(client): support Shadowsocks prefix for UDP (#2360)

client/go/outline/config/config_shadowsocks.go

@@ -71,6 +71,8 @@ func parseShadowsocksTransport(ctx context.Context, config ConfigNode, parseSE P
 	if err != nil {
 		return nil, fmt.Errorf("failed to create PacketListener: %w", err)
 	}
+	// For the Shadowsocks transport, the prefix only applies to TCP. To use a prefix with UDP, one needs to
+	// specify it in the PacketListener config explicitly. This is to ensure backwards-compatibility.
 	return &TransportPair{
 		&Dialer[transport.StreamConn]{ConnectionProviderInfo{ConnTypeTunneled, se.FirstHop}, sd.DialStream},
 		&PacketListener{ConnectionProviderInfo{ConnTypeTunneled, pe.FirstHop}, pl},
@@ -112,10 +114,6 @@ func parseShadowsocksPacketListener(ctx context.Context, config ConfigNode, pars
 	if err != nil {
 		return nil, err
 	}
-	if params.SaltGenerator != nil {
-		return nil, fmt.Errorf("prefix is not yet supported for PacketDialers")
-	}
-
 	pe, err := parsePE(ctx, params.Endpoint)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create PacketEndpoint: %w", err)
@@ -124,7 +122,9 @@ func parseShadowsocksPacketListener(ctx context.Context, config ConfigNode, pars
 	if err != nil {
 		return nil, err
 	}
-	// TODO: support UDP prefix.
+	if params.SaltGenerator != nil {
+		pl.SetSaltGenerator(params.SaltGenerator)
+	}
 	return &PacketListener{ConnectionProviderInfo{ConnTypeTunneled, pe.FirstHop}, pl}, nil
 }
 

go.mod

@@ -3,7 +3,7 @@ module github.com/Jigsaw-Code/outline-apps
 go 1.22.0
 
 require (
-	github.com/Jigsaw-Code/outline-sdk v0.0.18-0.20241106233708-faffebb12629
+	github.com/Jigsaw-Code/outline-sdk v0.0.18
 	github.com/Jigsaw-Code/outline-sdk/x v0.0.0-20250131142109-b32720fa2c3e
 	github.com/Wifx/gonetworkmanager/v2 v2.1.0
 	github.com/eycorsican/go-tun2socks v1.16.11

go.sum

@@ -59,10 +59,8 @@ cloud.google.com/go/storage v1.22.1/go.mod h1:S8N1cAStu7BOeFfE8KAQzmyyLkK8p/vmRq
 dmitri.shuralyov.com/gpu/mtl v0.0.0-20190408044501-666a987793e9/go.mod h1:H6x//7gZCb22OMCxBHrMx7a5I7Hp++hsVxbQ4BYO7hU=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
-github.com/Jigsaw-Code/outline-sdk v0.0.18-0.20241106233708-faffebb12629 h1:sHi1X4vwtNNBUDCbxynGXe7cM/inwTbavowHziaxlbk=
-github.com/Jigsaw-Code/outline-sdk v0.0.18-0.20241106233708-faffebb12629/go.mod h1:CFDKyGZA4zatKE4vMLe8TyQpZCyINOeRFbMAmYHxodw=
-github.com/Jigsaw-Code/outline-sdk/x v0.0.0-20250130191133-1f7340826841 h1:1tpY2KX6a9/1/uyN0riQVxQHqNthyAvzIhoWWmdYOBA=
-github.com/Jigsaw-Code/outline-sdk/x v0.0.0-20250130191133-1f7340826841/go.mod h1:9iEpNbKBsNU3WJs2XzhlI2AOf6DH018bjWxOC38o1Zc=
+github.com/Jigsaw-Code/outline-sdk v0.0.18 h1:xGzbag/jWGVQl5wGy0szr1jb+P8nVDFMcR2mWmgQnqc=
+github.com/Jigsaw-Code/outline-sdk v0.0.18/go.mod h1:CFDKyGZA4zatKE4vMLe8TyQpZCyINOeRFbMAmYHxodw=
 github.com/Jigsaw-Code/outline-sdk/x v0.0.0-20250131142109-b32720fa2c3e h1:JN3TZFpi98BTw/CZuQWxovFsgqjQ79gGrbvZE1wFIIc=
 github.com/Jigsaw-Code/outline-sdk/x v0.0.0-20250131142109-b32720fa2c3e/go.mod h1:aFUEz6Z/eD0NS3c3fEIX+JO2D9aIrXCmWTb1zJFlItw=
 github.com/Masterminds/semver/v3 v3.2.1 h1:RN9w6+7QoMeJVGyfmbcgs28Br8cvmnucEXnY0rYXWg0=
@@ -95,8 +93,6 @@ github.com/cncf/xds/go v0.0.0-20210805033703-aa0b78936158/go.mod h1:eXthEFrGJvWH
 github.com/cncf/xds/go v0.0.0-20210922020428-25de7278fc84/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211001041855-01bcc9b48dfe/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
 github.com/cncf/xds/go v0.0.0-20211011173535-cb28da3451f1/go.mod h1:eXthEFrGJvWHgFFCl3hGmgk+/aYT6PnTQLykKQRLhEs=
-github.com/coder/websocket v1.8.12 h1:5bUXkEPPIbewrnkU8LTCLVaxi4N4J8ahufH2vlo4NAo=
-github.com/coder/websocket v1.8.12/go.mod h1:LNVeNrXQZfe5qhS9ALED3uA+l5pPqvwXg3CKoDBB2gs=
 github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=