Enable splice for freedom outbound (downlink only)

- Add outbound name
- Add outbound conn in ctx
- Refactor splice: it can be turn on from all inbounds and outbounds
- Refactor splice: Add splice copy to vless inbound
- Fix http error test
- Add freedom splice toggle via env var
- Populate outbound obj in context
- Use CanSpliceCopy to mark a connection
- Turn off splice by default

proxy/vmess/outbound/outbound.go

@@ -60,9 +60,18 @@ func New(ctx context.Context, config *Config) (*Handler, error) {
 
 // Process implements proxy.Outbound.Process().
 func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer internet.Dialer) error {
+	outbound := session.OutboundFromContext(ctx)
+	if outbound == nil || !outbound.Target.IsValid() {
+		return newError("target not specified").AtError()
+	}
+	outbound.Name = "vmess"
+	inbound := session.InboundFromContext(ctx)
+	if inbound != nil {
+		inbound.SetCanSpliceCopy(3)
+	}
+
 	var rec *protocol.ServerSpec
 	var conn stat.Connection
-
 	err := retry.ExponentialBackoff(5, 200).On(func() error {
 		rec = h.serverPicker.PickServer()
 		rawConn, err := dialer.Dial(ctx, rec.Destination())
@@ -78,11 +87,6 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 	}
 	defer conn.Close()
 
-	outbound := session.OutboundFromContext(ctx)
-	if outbound == nil || !outbound.Target.IsValid() {
-		return newError("target not specified").AtError()
-	}
-
 	target := outbound.Target
 	newError("tunneling request to ", target, " via ", rec.Destination().NetAddr()).WriteToLog(session.ExportIDToError(ctx))