validator

README

Password validator library for Go

Installation

go get -u github.com/go-passwd/validator

Usage

import "github.com/go-passwd/validator"

passwordValidator := validator.New(validator.MinLength(5, nil), validator.MaxLength(10, nil))
err := passwordValidator.Validate(form.Password)
if err != nil {
  panic(err)
}

You can pass to every validator functions customError parameter witch will be returned on error instead of default error.

import "github.com/go-passwd/validator"

passwordValidator := validator.New(validator.MinLength(5, errors.New("too short")), validator.MaxLength(10, errors.New("too long")))
err := passwordValidator.Validate(form.Password)
if err != nil {
  panic(err)
}

Validators

CommonPassword

Check if password is a common password.

Common password list is based on list created by Mark Burnett: https://xato.net/passwords/more-top-worst-passwords/

passwordValidator := validator.New(validator.CommonPassword(nil))

ContainsAtLeast

Count occurrences of a chars and compares it with required value.

passwordValidator := validator.New(validator.ContainsAtLeast(5, "abcdefghijklmnopqrstuvwxyz", nil))

ContainsOnly

Check if password contains only selected chars.

passwordValidator := validator.New(validator.ContainsOnly("abcdefghijklmnopqrstuvwxyz", nil))

MaxLength

Check if password length is not greater that defined length.

passwordValidator := validator.New(validator.MaxLength(10, nil))

MinLength

Check if password length is not lower that defined length.

passwordValidator := validator.New(validator.MinLength(5, nil))

Noop

Always return custom error.

passwordValidator := validator.New(validator.Noop(nil))

Regex

Check if password match regexp pattern.

passwordValidator := validator.New(validator.Regex("^\\w+$", nil))

Similarity

Check if password is sufficiently different from the attributes.

Attributes can be: user login, email, first name, last name, …

passwordValidator := validator.New(validator.Similarity([]string{"username", "username@example.com"}, nil, nil))

StartsWith

Check if password starts with one of letter.

passwordValidator := validator.New(validator.StartsWith("abcdefghijklmnopqrstuvwxyz", nil))

Unique

Check if password contains only unique chars.

passwordValidator := validator.New(validator.Unique(nil))

Documentation

Overview

Package validator is a set of functions to validate passwords

Index

• type ValidateFunc
  • func CommonPassword(customError error) ValidateFunc
  • func ContainsAtLeast(chars string, occurrences int, customError error) ValidateFunc
  • func ContainsOnly(chars string, customError error) ValidateFunc
  • func MaxLength(length int, customError error) ValidateFunc
  • func MinLength(length int, customError error) ValidateFunc
  • func Noop(customError error) ValidateFunc
  • func Regex(pattern string, customError error) ValidateFunc
  • func Similarity(attributes []string, maxSimilarity *float64, customError error) ValidateFunc
  • func StartsWith(letters string, customError error) ValidateFunc
  • func Unique(customError error) ValidateFunc
• type Validator
  • func New(vfunc ...ValidateFunc) *Validator
  • func (v *Validator) Validate(password string) error

Examples

• CommonPassword
• CommonPassword (CustomError)
• ContainsAtLeast
• ContainsAtLeast (CustomError)
• ContainsOnly
• ContainsOnly (CustomError)
• MaxLength
• MaxLength (CustomError)
• MinLength
• MinLength (CustomError)
• New
• Noop
• Noop (CustomError)
• Regex
• Regex (CustomError)
• Similarity
• Similarity (CustomError)
• StartsWith
• StartsWith (CustomError)
• Unique
• Unique (CustomError)
• Validator.Validate

Types

type ValidateFunc

type ValidateFunc func(password string) error

ValidateFunc defines a function to validate

func CommonPassword

func CommonPassword(customError error) ValidateFunc

CommonPassword returns ValidateFunc that validate whether the password is a common password.

The password is rejected if it occurs in a provided list created by Mark Burnett: https://xato.net/passwords/more-top-worst-passwords/

Example

passwordValidator := CommonPassword(nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("qaz123"))
fmt.Println(passwordValidator("pa$$w0rd@"))

Output:

Password can't be a commonly used password
Password can't be a commonly used password
<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := CommonPassword(err)
fmt.Println(passwordValidator("password"))

Output:

custom error message

func ContainsAtLeast

func ContainsAtLeast(chars string, occurrences int, customError error) ValidateFunc

ContainsAtLeast returns a ValidateFunc that count occurrences of a chars and compares it with required value

Example

passwordValidator := ContainsAtLeast("abcdefghijklmnopqrstuvwxyz", 4, nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("PASSWORD"))
fmt.Println(passwordValidator("passWORD"))

Output:

<nil>
Password must contains at least 4 chars from abcdefghijklmnopqrstuvwxyz
<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := ContainsAtLeast("abcdefghijklmnopqrstuvwxyz", 4, err)
fmt.Println(passwordValidator("PASSWORD"))

Output:

custom error message

func ContainsOnly

func ContainsOnly(chars string, customError error) ValidateFunc

ContainsOnly returns a ValidateFunc that check if password contains only selected chars

Example

passwordValidator := ContainsOnly("abcdefghijklmnopqrstuvwxyz", nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("password0"))
fmt.Println(passwordValidator("passWORD"))

Output:

<nil>
the password must contains only abcdefghijklmnopqrstuvwxyz
the password must contains only abcdefghijklmnopqrstuvwxyz

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := ContainsOnly("abcdefghijklmnopqrstuvwxyz", err)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("password0"))
fmt.Println(passwordValidator("passWORD"))

Output:

<nil>
custom error message
custom error message

func MaxLength

func MaxLength(length int, customError error) ValidateFunc

MaxLength returns a ValidateFunc that check if password length is not greater that "length"

Example

passwordValidator := MaxLength(5, nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("pass"))
fmt.Println(passwordValidator("passw"))

Output:

Password length must be not greater that 5 chars
<nil>
<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := MaxLength(5, err)
fmt.Println(passwordValidator("password"))

Output:

custom error message

func MinLength

func MinLength(length int, customError error) ValidateFunc

MinLength returns a ValidateFunc that check if password length is not lower that "length"

Example

passwordValidator := MinLength(5, nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("pass"))
fmt.Println(passwordValidator("passw"))

Output:

<nil>
Password length must be not lower that 5 chars
<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := MinLength(5, err)
fmt.Println(passwordValidator("pass"))

Output:

custom error message

func Noop

func Noop(customError error) ValidateFunc

Noop returns a ValidateFunc that always return custom error

Example

passwordValidator := Noop(nil)
fmt.Println(passwordValidator("password"))

Output:

<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := Noop(err)
fmt.Println(passwordValidator("password"))

Output:

custom error message

func Regex

func Regex(pattern string, customError error) ValidateFunc

Regex returns ValidateFunc that check if password match regexp pattern

Example

passwordValidator := Regex("^\\w+$", nil)
fmt.Println(passwordValidator("password"))
fmt.Println(passwordValidator("pa$$w0rd"))

Output:

Password shouldn't match "^\w+$" pattern
<nil>

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := Regex("^\\w+$", err)
fmt.Println(passwordValidator("password"))

Output:

custom error message

func Similarity

func Similarity(attributes []string, maxSimilarity *float64, customError error) ValidateFunc

Similarity returns ValidateFunc that validate whether the password is sufficiently different from the attributes

Attributes can be: user login, email, first name, last name, …

Example

passwordValidator := Similarity([]string{"username", "username@example.com"}, nil, nil)
fmt.Println(passwordValidator("username"))
fmt.Println(passwordValidator("example"))
similarity := 0.5
passwordValidator = Similarity([]string{"username", "username@example.com"}, &similarity, nil)
fmt.Println(passwordValidator("username"))
fmt.Println(passwordValidator("examplecom"))

Output:

The password is too similar to the username
<nil>
The password is too similar to the username
The password is too similar to the username@example.com

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := Similarity([]string{"username", "username@example.com"}, nil, err)
fmt.Println(passwordValidator("username"))

Output:

custom error message

func StartsWith

func StartsWith(letters string, customError error) ValidateFunc

StartsWith returns ValidateFunc that validate whether the password is starts with one of letter

Example

passwordValidator := StartsWith("abc", nil)
fmt.Println(passwordValidator("bui87j"))
fmt.Println(passwordValidator("qwerty"))

Output:

<nil>
the password must starts with one of: abc

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := StartsWith("abc", err)
fmt.Println(passwordValidator("bui87j"))
fmt.Println(passwordValidator("qwerty"))

Output:

<nil>
custom error message

func Unique

func Unique(customError error) ValidateFunc

Unique returns ValidateFunc that validate whether the password has only unique chars

Example

passwordValidator := Unique(nil)
fmt.Println(passwordValidator("bui87j"))
fmt.Println(passwordValidator("qwerte"))

Output:

<nil>
the password must contains unique chars

Example (CustomError)

err := errors.New("custom error message")
passwordValidator := Unique(err)
fmt.Println(passwordValidator("bui87j"))
fmt.Println(passwordValidator("qwerte"))

Output:

<nil>
custom error message

type Validator

type Validator []ValidateFunc

Validator represents set of password validators

func New

func New(vfunc ...ValidateFunc) *Validator

New return new instance of Validator

Example

New(MinLength(5, nil), MaxLength(10, nil))

func (*Validator) Validate

func (v *Validator) Validate(password string) error

Validate the password

Example

passwordValidator := Validator{MinLength(5, nil), MaxLength(10, nil)}
fmt.Println(passwordValidator.Validate("password"))
fmt.Println(passwordValidator.Validate("pass1"))
fmt.Println(passwordValidator.Validate("password12"))
fmt.Println(passwordValidator.Validate("pass"))
fmt.Println(passwordValidator.Validate("password123"))

Output:

<nil>
<nil>
<nil>
Password length must be not lower that 5 chars
Password length must be not greater that 10 chars