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