44 lines
1.2 KiB
Go
44 lines
1.2 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package roottoken
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import (
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"crypto/rand"
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"encoding/base64"
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"fmt"
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"github.com/hashicorp/go-secure-stdlib/base62"
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)
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// DefaultBase64EncodedOTPLength is the number of characters that will be randomly generated
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// before the Base64 encoding process takes place.
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const defaultBase64EncodedOTPLength = 16
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// GenerateOTP generates a random token and encodes it as a Base64 or as a Base62 encoded string.
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// Returns 0 if the generation completed without any error, 2 otherwise, along with the error.
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func GenerateOTP(otpLength int) (string, error) {
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switch otpLength {
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case 0:
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// This is the fallback case
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buf := make([]byte, defaultBase64EncodedOTPLength)
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readLen, err := rand.Read(buf)
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if err != nil {
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return "", fmt.Errorf("error reading random bytes: %s", err)
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}
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if readLen != defaultBase64EncodedOTPLength {
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return "", fmt.Errorf("read %d bytes when we should have read 16", readLen)
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}
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return base64.StdEncoding.EncodeToString(buf), nil
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default:
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otp, err := base62.Random(otpLength)
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if err != nil {
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return "", fmt.Errorf("error reading random bytes: %w", err)
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}
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return otp, nil
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}
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}
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