66 lines
1.5 KiB
Go
66 lines
1.5 KiB
Go
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// Copyright (c) 2022 Tulir Asokan
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this
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// file, You can obtain one at http://mozilla.org/MPL/2.0/.
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package util
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import (
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"crypto/rand"
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"encoding/base64"
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"hash/crc32"
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"strings"
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"unsafe"
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)
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func RandomBytes(n int) []byte {
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data := make([]byte, n)
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_, err := rand.Read(data)
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if err != nil {
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panic(err)
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}
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return data
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}
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var letters = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
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// RandomString generates a random string of the given length.
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func RandomString(n int) string {
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if n <= 0 {
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return ""
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}
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base64Len := n
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if n%4 != 0 {
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base64Len += 4 - (n % 4)
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}
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decodedLength := base64.RawStdEncoding.DecodedLen(base64Len)
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output := make([]byte, base64Len)
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base64.RawStdEncoding.Encode(output, RandomBytes(decodedLength))
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for i, char := range output {
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if char == '+' || char == '/' {
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_, err := rand.Read(output[i : i+1])
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if err != nil {
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panic(err)
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}
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output[i] = letters[int(output[i])%len(letters)]
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}
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}
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return (*(*string)(unsafe.Pointer(&output)))[:n]
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}
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func base62Encode(val uint32, minWidth int) string {
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var buf strings.Builder
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for val > 0 {
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buf.WriteByte(letters[val%62])
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val /= 62
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}
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return strings.Repeat("0", minWidth-buf.Len()) + buf.String()
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}
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func RandomToken(namespace string, randomLength int) string {
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token := namespace + "_" + RandomString(randomLength)
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checksum := base62Encode(crc32.ChecksumIEEE([]byte(token)), 6)
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return token + "_" + checksum
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}
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