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ca1c5ee08f
The stringid package is used in many places; while it's trivial to implement a similar utility, let's just provide it as a utility package in the client, removing the daemon-specific logic. For integration tests, I opted to use the implementation in the client, as those should not ideally not make assumptions about the daemon implementation. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
71 lines
2.0 KiB
Go
71 lines
2.0 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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"strings"
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)
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const (
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shortLen = 12
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fullLen = 64
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)
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// TruncateID returns a shorthand version of a string identifier for presentation.
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// For convenience, it accepts both digests ("sha256:xxxx") and IDs without an
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// algorithm prefix. It truncates the algorithm (if any) before truncating the
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// ID. The length of the truncated ID is currently fixed, but users should make
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// no assumptions of this to not change; it is merely a prefix of the ID that
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// provides enough uniqueness for common scenarios.
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//
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// Truncated IDs ("ID-prefixes") usually can be used to uniquely identify an
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// object (such as a container or network), but collisions may happen, in
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// which case an "ambiguous result" error is produced. In case of a collision,
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// the caller should try with a longer prefix or the full-length ID.
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func TruncateID(id string) string {
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if i := strings.IndexRune(id, ':'); i >= 0 {
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id = id[i+1:]
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}
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if len(id) > shortLen {
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id = id[:shortLen]
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}
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return id
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}
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// GenerateRandomID returns a unique, 64-character ID consisting of a-z, 0-9.
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// It guarantees that the ID, when truncated ([TruncateID]) does not consist
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// of numbers only, so that the truncated ID can be used as hostname for
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// containers.
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func GenerateRandomID() string {
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b := make([]byte, 32)
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for {
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if _, err := rand.Read(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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// make sure that the truncated ID does not consist of only numeric
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// characters, as it's used as default hostname for containers.
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//
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// See:
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// - https://github.com/moby/moby/issues/3869
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// - https://bugzilla.redhat.com/show_bug.cgi?id=1059122
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if allNum(id[:shortLen]) {
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// all numbers; try again
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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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// allNum checks whether id consists of only numbers (0-9).
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func allNum(id string) bool {
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for _, c := range []byte(id) {
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if c > '9' || c < '0' {
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return false
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}
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}
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return true
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}
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