104 lines
2.8 KiB
Go
104 lines
2.8 KiB
Go
package mcrypto
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import (
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"bytes"
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"crypto/rand"
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"encoding/binary"
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"encoding/hex"
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"encoding/json"
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"errors"
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"fmt"
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"time"
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"github.com/mediocregopher/mediocre-go-lib/mlog"
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)
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const (
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uuidV0Prefix = "0u"
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uuidV0Len = 34 // prefix:2 + hexEncodedLen(time:8 + random:8)
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)
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// UUID is a universally unique identifier which embeds within it a timestamp.
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//
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// Only Unmarshal methods should be called on the zero UUID value.
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//
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// Comparing the equality of two UUID's should always be done using the Equal
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// method, or by comparing their string forms.
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//
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// The string form of UUIDs (returned by String or MarshalText) are
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// lexigraphically order-able by their embedded timestamp.
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type UUID struct {
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// the UUID type is actually just an opaque wrapper. For the most part
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// UUID's don't ever need the information in them (like their timestamp)
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// unpacked, so it's more efficient to just keep the string and unpack
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// on-the-fly
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str string
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}
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// NewUUID populates and returns a new UUID instance which embeds the given time
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func NewUUID(t time.Time) UUID {
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b := make([]byte, 16)
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binary.BigEndian.PutUint64(b[:8], uint64(t.UnixNano()))
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if _, err := rand.Read(b[8:]); err != nil {
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panic(err)
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}
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return UUID{
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str: uuidV0Prefix + hex.EncodeToString(b),
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}
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}
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func (u UUID) String() string {
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return u.str
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}
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// Equal returns whether or not the two UUID's are the same value
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func (u UUID) Equal(u2 UUID) bool {
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return u.str == u2.str
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}
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// Time unpacks and returns the timestamp embedded in the UUID
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func (u UUID) Time() time.Time {
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b, err := hex.DecodeString(u.str[2:])
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if err != nil {
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// once a UUID has been created it should always be valid
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panic(fmt.Sprintf("malformed UUID: %q", u.str))
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}
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unixNano := int64(binary.BigEndian.Uint64(b[:8]))
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return time.Unix(0, unixNano).Local()
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}
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// KV implements the method for the mlog.KVer interface
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func (u UUID) KV() mlog.KV {
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return mlog.KV{"uuid": u.String()}
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}
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// MarshalText implements the method for the encoding.TextMarshaler interface
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func (u UUID) MarshalText() ([]byte, error) {
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return []byte(u.String()), nil
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}
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// UnmarshalText implements the method for the encoding.TextUnmarshaler
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// interface
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func (u *UUID) UnmarshalText(b []byte) error {
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if !bytes.HasPrefix(b, []byte(uuidV0Prefix)) || len(b) != uuidV0Len {
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err := errors.New("malformed uuid string")
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return mlog.ErrWithKV(err, mlog.KV{"uuidStr": string(b)})
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}
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u.str = string(b)
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return nil
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}
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// MarshalJSON implements the method for the json.Marshaler interface
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func (u UUID) MarshalJSON() ([]byte, error) {
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return json.Marshal(u.String())
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}
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// UnmarshalJSON implements the method for the json.Unmarshaler interface
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func (u *UUID) UnmarshalJSON(b []byte) error {
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var s string
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if err := json.Unmarshal(b, &s); err != nil {
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return err
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}
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return u.UnmarshalText([]byte(s))
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}
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