mirror of
https://github.com/tmedwards/tweego.git
synced 2025-07-04 13:47:03 -04:00
85 lines
2 KiB
Go
85 lines
2 KiB
Go
/*
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Copyright © 2014–2019 Thomas Michael Edwards. All rights reserved.
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Use of this source code is governed by a Simplified BSD License which
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can be found in the LICENSE file.
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*/
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package main
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import (
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"crypto/rand"
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"fmt"
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"io"
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"strings"
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)
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// IFIDs are defined in The Treaty of Babel.
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// SEE: http://babel.ifarchive.org/
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//
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// Most IFIDs, and certainly those generated by Tweego, are simply the
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// string form of a v4 random UUID.
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// newIFID generates a new IFID (UUID v4).
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func newIFID() (string, error) {
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var uuid [16]byte
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if _, err := io.ReadFull(rand.Reader, uuid[:]); err != nil {
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return "", err
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}
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uuid[6] = (uuid[6] & 0x0f) | 0x40 // version 4
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uuid[8] = (uuid[8] & 0x3f) | 0x80 // variant 10
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return fmt.Sprintf("%X-%X-%X-%X-%X", uuid[0:4], uuid[4:6], uuid[6:8], uuid[8:10], uuid[10:]), nil
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}
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// validateIFID validates ifid or returns an error.
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func validateIFID(ifid string) error {
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switch len(ifid) {
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case 36: // xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
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case 36 + 9: // UUID://xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx//
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if strings.ToUpper(ifid[:7]) != "UUID://" || ifid[43:] != "//" {
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return fmt.Errorf("invalid IFID UUID://…// format")
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}
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ifid = ifid[7:43]
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default:
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return fmt.Errorf("invalid IFID length: %d", len(ifid))
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}
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b := []byte(ifid)
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for i := 0; i < len(b); i++ {
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switch i {
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// hyphens
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case 8, 13, 18, 23:
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if b[i] != '-' {
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return fmt.Errorf("invalid IFID character %#U at position %d", b[i], i+1)
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}
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// version
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case 14:
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if '1' > b[i] || b[i] > '5' {
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return fmt.Errorf("invalid version %#U at position %d", b[i], i+1)
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}
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// variant
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case 19:
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switch b[i] {
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case '8', '9', 'a', 'A', 'b', 'B':
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default:
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return fmt.Errorf("invalid variant %#U at position %d", b[i], i+1)
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}
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// regular hex character
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default:
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switch {
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case '0' <= b[i] && b[i] <= '9':
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case 'a' <= b[i] && b[i] <= 'f':
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case 'A' <= b[i] && b[i] <= 'F':
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default:
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return fmt.Errorf("invalid IFID hex value %#U at position %d", b[i], i+1)
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}
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}
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}
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return nil
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}
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