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// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package logtail
import (
"crypto/rand"
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
)
// PrivateID represents an instance that write logs.
// Private IDs are only shared with the server when writing logs.
type PrivateID [32]byte
// Safely generate a new PrivateId for use in Config objects.
// You should persist this across runs of an instance of your app, so that
// it can append to the same log file on each run.
func NewPrivateID() (id PrivateID, err error) {
_, err = rand.Read(id[:])
if err != nil {
return PrivateID{}, err
}
// Clamping, for future use.
id[0] &= 248
id[31] = (id[31] & 127) | 64
return id, nil
}
func (id PrivateID) MarshalText() ([]byte, error) {
b := make([]byte, hex.EncodedLen(len(id)))
if i := hex.Encode(b, id[:]); i != len(b) {
return nil, fmt.Errorf("logtail.PrivateID.MarhsalText: i=%d", i)
}
return b, nil
}
// ParsePrivateID returns a PrivateID from its hex (String) representation.
func ParsePrivateID(s string) (PrivateID, error) {
if len(s) != 64 {
return PrivateID{}, errors.New("invalid length")
}
var p PrivateID
for i := range p {
a, ok1 := fromHexChar(s[i*2+0])
b, ok2 := fromHexChar(s[i*2+1])
if !ok1 || !ok2 {
return PrivateID{}, errors.New("invalid hex character")
}
p[i] = (a << 4) | b
}
return p, nil
}
// IsZero reports whether id is the zero value.
func (id PrivateID) IsZero() bool { return id == PrivateID{} }
func (id *PrivateID) UnmarshalText(s []byte) error {
b, err := hex.DecodeString(string(s))
if err != nil {
return fmt.Errorf("logtail.PrivateID.UnmarshalText: %v", err)
}
if len(b) != len(id) {
return fmt.Errorf("logtail.PrivateID.UnmarshalText: invalid hex length: %d", len(b))
}
copy(id[:], b)
return nil
}
func (id PrivateID) String() string {
b, err := id.MarshalText()
if err != nil {
panic(err)
}
return string(b)
}
func (id PrivateID) Public() (pub PublicID) {
var emptyID PrivateID
if id == emptyID {
panic("invalid logtail.Public() on an empty private ID")
}
h := sha256.New()
h.Write(id[:])
if n := copy(pub[:], h.Sum(pub[:0])); n != len(pub) {
panic(fmt.Sprintf("public id short copy: %d", n))
}
return pub
}
// PublicID represents an instance in the logs service for reading and adoption.
// The public ID value is a SHA-256 hash of a private ID.
type PublicID [sha256.Size]byte
// ParsePublicID returns a PublicID from its hex (String) representation.
func ParsePublicID(s string) (PublicID, error) {
if len(s) != sha256.Size*2 {
return PublicID{}, errors.New("invalid length")
}
var p PublicID
for i := range p {
a, ok1 := fromHexChar(s[i*2+0])
b, ok2 := fromHexChar(s[i*2+1])
if !ok1 || !ok2 {
return PublicID{}, errors.New("invalid hex character")
}
p[i] = (a << 4) | b
}
return p, nil
}
func (id PublicID) MarshalText() ([]byte, error) {
b := make([]byte, hex.EncodedLen(len(id)))
if i := hex.Encode(b, id[:]); i != len(b) {
return nil, fmt.Errorf("logtail.PublicID.MarhsalText: i=%d", i)
}
return b, nil
}
func (id *PublicID) UnmarshalText(s []byte) error {
if len(s) != len(id)*2 {
return fmt.Errorf("logtail.PublicID.UnmarshalText: invalid hex length: %d", len(s))
}
for i := range id {
a, ok1 := fromHexChar(s[i*2+0])
b, ok2 := fromHexChar(s[i*2+1])
if !ok1 || !ok2 {
return errors.New("invalid hex character")
}
id[i] = (a << 4) | b
}
return nil
}
func (id PublicID) String() string {
b, err := id.MarshalText()
if err != nil {
panic(err)
}
return string(b)
}
// fromHexChar converts a hex character into its value and a success flag.
func fromHexChar(c byte) (byte, bool) {
switch {
case '0' <= c && c <= '9':
return c - '0', true
case 'a' <= c && c <= 'f':
return c - 'a' + 10, true
case 'A' <= c && c <= 'F':
return c - 'A' + 10, true
}
return 0, false
}
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