forked from go-oauth2/oauth2
/
uuid.go
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/
uuid.go
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package uuid
import (
"crypto/md5"
"crypto/rand"
"crypto/sha1"
"encoding/hex"
"hash"
"io"
)
// Nil empty UUID, all zeros
var Nil UUID
// A UUID is a 128 bit (16 byte) Universal Unique IDentifier as defined in RFC
// 4122.
type UUID [16]byte
// Bytes returns bytes slice representation of UUID.
func (uuid UUID) Bytes() []byte {
return uuid[:]
}
// String returns the string form of uuid, xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
// , or "" if uuid is invalid.
func (uuid UUID) String() string {
var buf [36]byte
encodeHex(buf[:], uuid)
return string(buf[:])
}
func encodeHex(dst []byte, uuid UUID) {
hex.Encode(dst, uuid[:4])
dst[8] = '-'
hex.Encode(dst[9:13], uuid[4:6])
dst[13] = '-'
hex.Encode(dst[14:18], uuid[6:8])
dst[18] = '-'
hex.Encode(dst[19:23], uuid[8:10])
dst[23] = '-'
hex.Encode(dst[24:], uuid[10:])
}
// Must returns uuid if err is nil and panics otherwise.
func Must(uuid UUID, err error) UUID {
if err != nil {
panic(err)
}
return uuid
}
// NewRandom returns a Random (Version 4) UUID.
//
// The strength of the UUIDs is based on the strength of the crypto/rand
// package.
//
// A note about uniqueness derived from the UUID Wikipedia entry:
//
// Randomly generated UUIDs have 122 random bits. One's annual risk of being
// hit by a meteorite is estimated to be one chance in 17 billion, that
// means the probability is about 0.00000000006 (6 × 10−11),
// equivalent to the odds of creating a few tens of trillions of UUIDs in a
// year and having one duplicate.
func NewRandom() (UUID, error) {
var uuid UUID
_, err := io.ReadFull(rand.Reader, uuid[:])
if err != nil {
return Nil, err
}
uuid[6] = (uuid[6] & 0x0f) | 0x40 // Version 4
uuid[8] = (uuid[8] & 0x3f) | 0x80 // Variant is 10
return uuid, nil
}
// NewHash returns a new UUID derived from the hash of space concatenated with
// data generated by h. The hash should be at least 16 byte in length. The
// first 16 bytes of the hash are used to form the UUID. The version of the
// UUID will be the lower 4 bits of version.
func NewHash(h hash.Hash, space UUID, data []byte, version int) UUID {
h.Reset()
h.Write(space[:])
h.Write(data)
s := h.Sum(nil)
var uuid UUID
copy(uuid[:], s)
uuid[6] = (uuid[6] & 0x0f) | uint8((version&0xf)<<4)
uuid[8] = (uuid[8] & 0x3f) | 0x80 // RFC 4122 variant
return uuid
}
// NewMD5 returns a new MD5 (Version 3) UUID based on the
// supplied name space and data. It is the same as calling:
//
// NewHash(md5.New(), space, data, 3)
func NewMD5(space UUID, data []byte) UUID {
return NewHash(md5.New(), space, data, 3)
}
// NewSHA1 returns a new SHA1 (Version 5) UUID based on the
// supplied name space and data. It is the same as calling:
//
// NewHash(sha1.New(), space, data, 5)
func NewSHA1(space UUID, data []byte) UUID {
return NewHash(sha1.New(), space, data, 5)
}