| // Package stringid provides helper functions for dealing with string identifiers |
| package stringid |
| |
| import ( |
| "crypto/rand" |
| "encoding/hex" |
| "io" |
| "regexp" |
| "strconv" |
| "strings" |
| |
| "github.com/docker/docker/pkg/random" |
| ) |
| |
| const shortLen = 12 |
| |
| var validShortID = regexp.MustCompile("^[a-z0-9]{12}$") |
| |
| // IsShortID determines if an arbitrary string *looks like* a short ID. |
| func IsShortID(id string) bool { |
| return validShortID.MatchString(id) |
| } |
| |
| // TruncateID returns a shorthand version of a string identifier for convenience. |
| // A collision with other shorthands is very unlikely, but possible. |
| // In case of a collision a lookup with TruncIndex.Get() will fail, and the caller |
| // will need to use a langer prefix, or the full-length Id. |
| func TruncateID(id string) string { |
| if i := strings.IndexRune(id, ':'); i >= 0 { |
| id = id[i+1:] |
| } |
| trimTo := shortLen |
| if len(id) < shortLen { |
| trimTo = len(id) |
| } |
| return id[:trimTo] |
| } |
| |
| func generateID(crypto bool) string { |
| b := make([]byte, 32) |
| r := random.Reader |
| if crypto { |
| r = rand.Reader |
| } |
| for { |
| if _, err := io.ReadFull(r, b); err != nil { |
| panic(err) // This shouldn't happen |
| } |
| id := hex.EncodeToString(b) |
| // if we try to parse the truncated for as an int and we don't have |
| // an error then the value is all numeric and causes issues when |
| // used as a hostname. ref #3869 |
| if _, err := strconv.ParseInt(TruncateID(id), 10, 64); err == nil { |
| continue |
| } |
| return id |
| } |
| } |
| |
| // GenerateRandomID returns an unique id. |
| func GenerateRandomID() string { |
| return generateID(true) |
| |
| } |
| |
| // GenerateNonCryptoID generates unique id without using cryptographically |
| // secure sources of random. |
| // It helps you to save entropy. |
| func GenerateNonCryptoID() string { |
| return generateID(false) |
| } |