mirror of
https://github.com/moby/moby.git
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39 lines
1,019 B
Go
39 lines
1,019 B
Go
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package common
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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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"strconv"
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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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shortLen := 12
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if len(id) < shortLen {
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shortLen = len(id)
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}
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return id[:shortLen]
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}
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// GenerateRandomID returns an unique id
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func GenerateRandomID() string {
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for {
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id := make([]byte, 32)
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if _, err := io.ReadFull(rand.Reader, id); err != nil {
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panic(err) // This shouldn't happen
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}
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value := hex.EncodeToString(id)
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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(value), 10, 64); err == nil {
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continue
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}
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return value
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}
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}
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