Butler stream servers can generate client address.

logdog/client/butlerlib/streamclient/client.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package streamclient
 
 import (
         "encoding/json"
         "fmt"
         "io"
@@ skipping 52 matching lines @@
                         client.Close()
                 }
         }()
 
         data, err := json.Marshal(f)
         if err != nil {
                 return nil, fmt.Errorf("failed to marshal properties JSON: %s", err)
         }
 
         // Perform the handshake: magic + size(data) + data.
-        s := &streamImpl{
+        s := &BaseStream{
                 WriteCloser: client,
-                props:       p,
+                P:           p,
         }
         if _, err := s.writeRaw(streamproto.ProtocolFrameHeaderMagic); err != nil {
                 return nil, fmt.Errorf("failed to write magic number: %s", err)
         }
         if err := s.writeRecord(data); err != nil {
                 return nil, fmt.Errorf("failed to write properties: %s", err)
         }
 
         ownsClient = false // Passing ownership to caller.
         return s, nil
 }