354 lines
8.3 KiB
Go
354 lines
8.3 KiB
Go
// Copyright (C) 2013 by Maxim Bublis <b@codemonkey.ru>
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//
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// Permission is hereby granted, free of charge, to any person obtaining
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// a copy of this software and associated documentation files (the
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// "Software"), to deal in the Software without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Software, and to
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// permit persons to whom the Software is furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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// Package uuid provides implementation of Universally Unique Identifier (UUID).
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// Supported versions are 1, 3, 4 and 5 (as specified in RFC 4122) and
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// version 2 (as specified in DCE 1.1).
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package uuid
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import (
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"bytes"
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"crypto/md5"
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"crypto/rand"
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"crypto/sha1"
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"encoding/binary"
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"encoding/hex"
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"fmt"
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"hash"
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"net"
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"os"
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"strings"
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"sync"
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"time"
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)
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// UUID layout variants.
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const (
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VariantNCS = iota
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VariantRFC4122
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VariantMicrosoft
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VariantFuture
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)
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// UUID DCE domains.
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const (
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DomainPerson = iota
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DomainGroup
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DomainOrg
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)
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// Difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and Unix epoch (January 1, 1970).
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const epochStart = 122192928000000000
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// UUID v1/v2 storage.
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var (
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storageMutex sync.Mutex
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clockSequence uint16
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lastTime uint64
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hardwareAddr [6]byte
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posixUID = uint32(os.Getuid())
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posixGID = uint32(os.Getgid())
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)
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// Epoch calculation function
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var epochFunc func() uint64
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// Initialize storage
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func init() {
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buf := make([]byte, 2)
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rand.Read(buf)
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clockSequence = binary.BigEndian.Uint16(buf)
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// Initialize hardwareAddr randomly in case
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// of real network interfaces absence
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rand.Read(hardwareAddr[:])
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// Set multicast bit as recommended in RFC 4122
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hardwareAddr[0] |= 0x01
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interfaces, err := net.Interfaces()
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if err == nil {
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for _, iface := range interfaces {
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if len(iface.HardwareAddr) >= 6 {
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copy(hardwareAddr[:], iface.HardwareAddr)
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break
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}
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}
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}
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epochFunc = unixTimeFunc
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}
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// Returns difference in 100-nanosecond intervals between
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// UUID epoch (October 15, 1582) and current time.
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// This is default epoch calculation function.
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func unixTimeFunc() uint64 {
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return epochStart + uint64(time.Now().UnixNano()/100)
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}
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// UUID representation compliant with specification
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// described in RFC 4122.
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type UUID [16]byte
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// Predefined namespace UUIDs.
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var (
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NamespaceDNS, _ = FromString("6ba7b810-9dad-11d1-80b4-00c04fd430c8")
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NamespaceURL, _ = FromString("6ba7b811-9dad-11d1-80b4-00c04fd430c8")
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NamespaceOID, _ = FromString("6ba7b812-9dad-11d1-80b4-00c04fd430c8")
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NamespaceX500, _ = FromString("6ba7b814-9dad-11d1-80b4-00c04fd430c8")
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)
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// And returns result of binary AND of two UUIDs.
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func And(u1 UUID, u2 UUID) UUID {
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u := UUID{}
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for i := 0; i < 16; i++ {
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u[i] = u1[i] & u2[i]
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}
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return u
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}
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// Or returns result of binary OR of two UUIDs.
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func Or(u1 UUID, u2 UUID) UUID {
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u := UUID{}
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for i := 0; i < 16; i++ {
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u[i] = u1[i] | u2[i]
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}
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return u
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}
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// Equal returns true if u1 and u2 equals, otherwise returns false.
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func Equal(u1 UUID, u2 UUID) bool {
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return bytes.Equal(u1[:], u2[:])
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}
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// Version returns algorithm version used to generate UUID.
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func (u UUID) Version() uint {
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return uint(u[6] >> 4)
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}
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// Variant returns UUID layout variant.
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func (u UUID) Variant() uint {
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switch {
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case (u[8] & 0x80) == 0x00:
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return VariantNCS
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case (u[8]&0xc0)|0x80 == 0x80:
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return VariantRFC4122
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case (u[8]&0xe0)|0xc0 == 0xc0:
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return VariantMicrosoft
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}
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return VariantFuture
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}
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// Bytes returns bytes slice representation of UUID.
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func (u UUID) Bytes() []byte {
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return u[:]
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}
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// Returns canonical string representation of UUID:
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// xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
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func (u UUID) String() string {
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return fmt.Sprintf("%x-%x-%x-%x-%x",
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u[:4], u[4:6], u[6:8], u[8:10], u[10:])
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}
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// SetVersion sets version bits.
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func (u *UUID) SetVersion(v byte) {
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u[6] = (u[6] & 0x0f) | (v << 4)
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}
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// SetVariant sets variant bits as described in RFC 4122.
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func (u *UUID) SetVariant() {
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u[8] = (u[8] & 0xbf) | 0x80
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}
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// MarshalText implements the encoding.TextMarshaler interface.
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// The encoding is the same as returned by String.
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func (u UUID) MarshalText() (text []byte, err error) {
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text = []byte(u.String())
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return
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}
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// UnmarshalText implements the encoding.TextUnmarshaler interface.
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// UUID is expected in a form accepted by FromString.
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func (u *UUID) UnmarshalText(text []byte) error {
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s := string(text)
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u2, err := FromString(s)
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if err != nil {
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return err
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}
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*u = u2
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return nil
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}
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// MarshalBinary implements the encoding.BinaryMarshaler interface.
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func (u UUID) MarshalBinary() (data []byte, err error) {
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data = u.Bytes()
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return
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}
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// UnmarshalBinary implements the encoding.BinaryUnmarshaler interface.
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func (u *UUID) UnmarshalBinary(data []byte) error {
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u2, err := FromBytes(data)
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if err != nil {
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return err
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}
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*u = u2
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return nil
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}
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// FromBytes returns UUID converted from raw byte slice input.
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// It will return error if the slice isn't 16 bytes long.
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func FromBytes(input []byte) (u UUID, err error) {
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if len(input) != 16 {
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err = fmt.Errorf("uuid: UUID must be exactly 16 bytes long, got %d bytes", len(input))
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return
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}
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copy(u[:], input)
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return
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}
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// FromString returns UUID parsed from string input.
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// Following formats are supported:
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// "6ba7b810-9dad-11d1-80b4-00c04fd430c8",
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// "{6ba7b810-9dad-11d1-80b4-00c04fd430c8}",
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// "urn:uuid:6ba7b810-9dad-11d1-80b4-00c04fd430c8"
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func FromString(input string) (u UUID, err error) {
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s := strings.Replace(input, "-", "", -1)
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if len(s) == 41 && s[:9] == "urn:uuid:" {
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s = s[9:]
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} else if len(s) == 34 && s[0] == '{' && s[33] == '}' {
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s = s[1:33]
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}
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if len(s) != 32 {
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err = fmt.Errorf("uuid: invalid UUID string: %s", input)
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return
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}
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b := []byte(s)
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_, err = hex.Decode(u[:], b)
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return
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}
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// Returns UUID v1/v2 storage state.
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// Returns epoch timestamp and clock sequence.
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func getStorage() (uint64, uint16) {
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storageMutex.Lock()
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defer storageMutex.Unlock()
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timeNow := epochFunc()
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// Clock changed backwards since last UUID generation.
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// Should increase clock sequence.
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if timeNow <= lastTime {
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clockSequence++
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}
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lastTime = timeNow
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return timeNow, clockSequence
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}
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// NewV1 returns UUID based on current timestamp and MAC address.
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func NewV1() UUID {
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u := UUID{}
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timeNow, clockSeq := getStorage()
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binary.BigEndian.PutUint32(u[0:], uint32(timeNow))
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binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
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binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
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binary.BigEndian.PutUint16(u[8:], clockSeq)
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copy(u[10:], hardwareAddr[:])
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u.SetVersion(1)
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u.SetVariant()
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return u
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}
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// NewV2 returns DCE Security UUID based on POSIX UID/GID.
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func NewV2(domain byte) UUID {
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u := UUID{}
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switch domain {
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case DomainPerson:
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binary.BigEndian.PutUint32(u[0:], posixUID)
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case DomainGroup:
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binary.BigEndian.PutUint32(u[0:], posixGID)
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}
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timeNow, clockSeq := getStorage()
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binary.BigEndian.PutUint16(u[4:], uint16(timeNow>>32))
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binary.BigEndian.PutUint16(u[6:], uint16(timeNow>>48))
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binary.BigEndian.PutUint16(u[8:], clockSeq)
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u[9] = domain
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copy(u[10:], hardwareAddr[:])
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u.SetVersion(2)
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u.SetVariant()
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return u
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}
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// NewV3 returns UUID based on MD5 hash of namespace UUID and name.
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func NewV3(ns UUID, name string) UUID {
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u := newFromHash(md5.New(), ns, name)
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u.SetVersion(3)
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u.SetVariant()
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return u
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}
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// NewV4 returns random generated UUID.
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func NewV4() UUID {
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u := UUID{}
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rand.Read(u[:])
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u.SetVersion(4)
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u.SetVariant()
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return u
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}
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// NewV5 returns UUID based on SHA-1 hash of namespace UUID and name.
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func NewV5(ns UUID, name string) UUID {
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u := newFromHash(sha1.New(), ns, name)
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u.SetVersion(5)
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u.SetVariant()
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return u
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}
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// Returns UUID based on hashing of namespace UUID and name.
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func newFromHash(h hash.Hash, ns UUID, name string) UUID {
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u := UUID{}
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h.Write(ns[:])
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h.Write([]byte(name))
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copy(u[:], h.Sum(nil))
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return u
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}
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