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// Copyright 2016 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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package uuid
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import (
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	"encoding/binary"
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	"fmt"
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	"os"
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)
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// A Domain represents a Version 2 domain
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type Domain byte
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// Domain constants for DCE Security (Version 2) UUIDs.
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const (
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	Person = Domain(0)
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	Group  = Domain(1)
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	Org    = Domain(2)
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)
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// NewDCESecurity returns a DCE Security (Version 2) UUID.
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//
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// The domain should be one of Person, Group or Org.
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// On a POSIX system the id should be the users UID for the Person
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// domain and the users GID for the Group.  The meaning of id for
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// the domain Org or on non-POSIX systems is site defined.
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//
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// For a given domain/id pair the same token may be returned for up to
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// 7 minutes and 10 seconds.
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func NewDCESecurity(domain Domain, id uint32) (UUID, error) {
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	uuid, err := NewUUID()
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	if err == nil {
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		uuid[6] = (uuid[6] & 0x0f) | 0x20 // Version 2
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		uuid[9] = byte(domain)
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		binary.BigEndian.PutUint32(uuid[0:], id)
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	}
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	return uuid, err
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}
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// NewDCEPerson returns a DCE Security (Version 2) UUID in the person
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// domain with the id returned by os.Getuid.
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//
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//  NewDCESecurity(Person, uint32(os.Getuid()))
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func NewDCEPerson() (UUID, error) {
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	return NewDCESecurity(Person, uint32(os.Getuid()))
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}
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// NewDCEGroup returns a DCE Security (Version 2) UUID in the group
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// domain with the id returned by os.Getgid.
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//
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//  NewDCESecurity(Group, uint32(os.Getgid()))
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func NewDCEGroup() (UUID, error) {
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	return NewDCESecurity(Group, uint32(os.Getgid()))
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}
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// Domain returns the domain for a Version 2 UUID.  Domains are only defined
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// for Version 2 UUIDs.
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func (uuid UUID) Domain() Domain {
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	return Domain(uuid[9])
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}
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// ID returns the id for a Version 2 UUID. IDs are only defined for Version 2
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// UUIDs.
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func (uuid UUID) ID() uint32 {
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	return binary.BigEndian.Uint32(uuid[0:4])
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}
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func (d Domain) String() string {
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	switch d {
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	case Person:
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		return "Person"
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	case Group:
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		return "Group"
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	case Org:
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		return "Org"
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	}
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	return fmt.Sprintf("Domain%d", int(d))
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}
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