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// Copyright 2017 Google Inc.  All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build !js
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package uuid
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import "net"
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var interfaces []net.Interface // cached list of interfaces
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// getHardwareInterface returns the name and hardware address of interface name.
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// If name is "" then the name and hardware address of one of the system's
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// interfaces is returned.  If no interfaces are found (name does not exist or
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// there are no interfaces) then "", nil is returned.
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//
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// Only addresses of at least 6 bytes are returned.
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func getHardwareInterface(name string) (string, []byte) {
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	if interfaces == nil {
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		var err error
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		interfaces, err = net.Interfaces()
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		if err != nil {
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			return "", nil
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		}
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	}
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	for _, ifs := range interfaces {
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		if len(ifs.HardwareAddr) >= 6 && (name == "" || name == ifs.Name) {
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			return ifs.Name, ifs.HardwareAddr
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		}
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	}
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	return "", nil
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}
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