Butler stream servers can generate client address.

logdog/client/butler/streamserver/namedPipe_windows.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 streamserver
 
 import (
         "net"
 
+        "github.com/luci/luci-go/common/errors"
         log "github.com/luci/luci-go/common/logging"
+        "github.com/luci/luci-go/logdog/client/butlerlib/streamclient"
+
         "golang.org/x/net/context"
         npipe "gopkg.in/natefinch/npipe.v2"
 )
 
+// maxWindowsNamedPipeLength is the maximum length of a Windows named pipe.
+const maxWindowsNamedPipeLength = 256
+
 // NewNamedPipeServer instantiates a new Windows named pipe server instance.
-func NewNamedPipeServer(ctx context.Context, address string) StreamServer {
-        ctx = log.SetField(ctx, "address", address)
+func NewNamedPipeServer(ctx context.Context, name string) (StreamServer, error) {
+        switch l := len(name); {
+        case l == 0:
+                return nil, errors.New("cannot have empty name")
+        case l > maxWindowsNamedPipeLength:
+                return nil, errors.Reason("name exceeds maximum length %(max)d").
+                        D("name", name).
+                        D("max", maxWindowsNamedPipeLength).
+                        Err()
+        }
+
+        ctx = log.SetField(ctx, "name", name)
         return &listenerStreamServer{
                 Context: ctx,
-                gen: func() (net.Listener, error) {
-                        log.Debugf(ctx, "Creating Windows server socket Listener.")
-                        return npipe.Listen(address)
+                gen: func() (net.Listener, string, error) {
+                        address := "net.pipe:" + name
+                        pipePath := streamclient.LocalNamedPipePath(name)
+                        log.Fields{
+                                "addr":     address,
+                                "pipePath": pipePath,
+                        }.Debugf(ctx, "Creating Windows server socket Listener.")
+
+                        l, err := npipe.Listen(pipePath)
+                        if err != nil {
+                                return nil, "", errors.Annotate(err).Reason("failed to listen on named pipe").Err()
+                        }
+                        return l, address, nil
                 },
-        }
+        }, nil
 }