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ad90e0b39d
* Add random string generator with rules engine This adds a random string generation library that validates random strings against a set of rules. The library is designed for use as generating passwords, but can be used to generate any random strings.
92 lines
2.3 KiB
Go
92 lines
2.3 KiB
Go
package random
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import (
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"fmt"
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"github.com/mitchellh/mapstructure"
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)
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// Rule to assert on string values.
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type Rule interface {
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// Pass should return true if the provided value passes any assertions this Rule is making.
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Pass(value []rune) bool
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// Type returns the name of the rule as associated in the registry
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Type() string
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}
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// CharsetRule requires a certain number of characters from the specified charset.
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type CharsetRule struct {
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// CharsetRule is the list of rules that candidate strings must contain a minimum number of.
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Charset runes `mapstructure:"charset" json:"charset"`
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// MinChars indicates the minimum (inclusive) number of characters from the charset that should appear in the string.
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MinChars int `mapstructure:"min-chars" json:"min-chars"`
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}
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// ParseCharset from the provided data map. The data map is expected to be parsed from HCL.
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func ParseCharset(data map[string]interface{}) (rule Rule, err error) {
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cr := &CharsetRule{}
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decoder, err := mapstructure.NewDecoder(&mapstructure.DecoderConfig{
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Metadata: nil,
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Result: cr,
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DecodeHook: stringToRunesFunc,
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})
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if err != nil {
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return nil, fmt.Errorf("unable to decode charset restriction: %w", err)
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}
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err = decoder.Decode(data)
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if err != nil {
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return nil, fmt.Errorf("failed to parse charset restriction: %w", err)
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}
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return *cr, nil
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}
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func (c CharsetRule) Type() string {
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return "charset"
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}
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// Chars returns the charset that this rule is looking for.
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func (c CharsetRule) Chars() []rune {
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return c.Charset
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}
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func (c CharsetRule) MinLength() int {
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return c.MinChars
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}
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// Pass returns true if the provided candidate string has a minimum number of chars in it.
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// This adheres to the Rule interface
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func (c CharsetRule) Pass(value []rune) bool {
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if c.MinChars <= 0 {
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return true
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}
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count := 0
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for _, r := range value {
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// charIn is sometimes faster than a map lookup because the data is so small
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// This is being kept rather than converted to a map to keep the code cleaner,
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// otherwise there would need to be additional parsing logic.
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if charIn(r, c.Charset) {
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count++
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if count >= c.MinChars {
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return true
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}
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}
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}
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return false
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}
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func charIn(search rune, charset []rune) bool {
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for _, r := range charset {
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if search == r {
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return true
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}
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}
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return false
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}
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