Goyave

# Authentication

Since v2.5.0

# Introduction

Goyave provides a convenient and expandable way of handling authentication in your application. Authentication can be enabled when registering your routes:

import "goyave.dev/goyave/v4/auth"

//...

authenticator := auth.Middleware(&model.User{}, &auth.BasicAuthenticator{})
router.Middleware(authenticator)

Authentication is handled by a simple middleware calling an Authenticator. This middleware also needs a model, which will be used to fetch user information on a successful login.

# auth.Middleware

Middleware create a new authenticator middleware to authenticate the given model using the given authenticator.

Parameters Return
model interface{} goyave.Middleware
authenticator Authenticator

Example:

authenticator := auth.Middleware(&model.User{}, &auth.BasicAuthenticator{})
router.Middleware(authenticator)

# Authenticators

This section will go into more details about Authenticators and explain the built-in ones. You will also learn how to implement an authenticator yourself.

Authenticator is a functional interface with a single method accepting a request and a model pointer as parameters.

Authenticate(request *goyave.Request, user interface{}) error

The goal of this function is to check user credentials, most of the time from the request's headers. If they are correct and the user can be authenticated, the user parameter is updated with the user's information. User information is most of the time fetched from the database.

On the other hand, if the user cannot be authenticated, the Authenticate method must return an error containing a localized message. For example, the error could be that the token lifetime is expired, thus "Your authentication token is expired." will be returned.

Authenticators use their model's struct fields tags to know which field to use for username and password. To make your model compatible with authentication, you must add the auth:"username" and auth:"password" tags:

type User struct {
	gorm.Model
	Email    string `gorm:"type:char(100);uniqueIndex" auth:"username"`
	Name     string `gorm:"type:char(100)"`
	Password string `gorm:"type:char(60)" auth:"password"`
}

WARNING

  • The username should be unique.
  • Passwords should be hashed before being stored in the database.

Built-in Goyave Authenticators use bcrypt (opens new window) to check if a password matches the user request.

When a user is successfully authenticated on a protected route, its information is available in the controller handler, through the request User field.

func Hello(response *goyave.Response, request *goyave.Request) {
	user := request.User.(*model.User)
	response.String(http.StatusOK, "Hello " + user.Name)
}

TIP

Remember that Goyave is primarily focused on APIs. It doesn't use session nor cookies in its core features, making requests stateless.

If you want to implement cookie or session-based authentication, be sure to protect your application from CSRF attacks (opens new window).

# Basic Auth

Basic authentication (opens new window) is an authentication method using the Authorization header and a simple username and password combination with the following format: username:password, encoded in base64. There are two built-in Authenticators for Basic auth.

# Database provider

This Authenticator fetches the user information from the database, using the field tags explained earlier.

To apply this protection to your routes, add the following middleware:

authenticator := auth.Middleware(&model.User{}, &auth.BasicAuthenticator{})
router.Middleware(authenticator)

You can then try requesting a protected route:

$ curl -u username:password http://localhost:8080/hello
Hello Jérémy

This provider supports the Optional flag, which defines if the authenticator allows requests that don't provide credentials. Handlers should therefore check if request.User is not nil before accessing it.

authenticator := auth.Middleware(&model.User{}, &auth.BasicAuthenticator{Optional: true})
router.Middleware(authenticator)

# Config provider

This Authenticator fetches the user information from the config. This method is good for quick proof-of-concepts, as it requires minimum setup, but shouldn't be used in real-world applications.

  • The auth.basic.username config entry defines the username that must be matched.
  • The auth.basic.password config entry defines the password that must be matched.

To apply this protection to your routes, start by adding the auth category at the root of your configuration, and the auth.basic sub-category:

{
  ...
  "auth": {
    "basic": {
      "username": "admin",
      "password": "admin"
    }
  }
}

Then, add the following middleware:

router.Middleware(auth.ConfigBasicAuth())

The model used for this Authenticator is auth.BasicUser:

type BasicUser struct {
	Name string
}

You can then try requesting a protected route:

$ curl -u username:password http://localhost:8080/hello

# auth.ConfigBasicAuth

Create a new authenticator middleware for config-based Basic authentication. On auth success, the request user is set to a auth.BasicUser. The user is authenticated if the auth.basic.username and auth.basic.password config entries match the request's Authorization header.

Parameters Return
goyave.Middleware

# JSON Web Token (JWT)

JWT, or JSON Web Token (opens new window), is an open standard of authentication that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted because it is digitally signed. JWTs can be signed using a secret (with the HMAC algorithm) or a public/private key pair using RSA or ECDSA. Goyave supports HMAC, RSA (with or without password) and ECDSA. RSA and ECDSA require PEM-encoded keys. Goyave uses the golang-jwt/jwt (opens new window) library in the background.

JWT Authentication comes with the auth.jwt.expiry configuration entry, which defines the number of seconds a token is valid for and defaults to 300 (5 minutes).

# Basic usage

By default, Goyave's built-in JWT components will use HMAC-SHA256 to sign generated tokens and will expect this method for signature verification. In this basic usage example, this is what we are going to use. Check the next sections for details on how to use RSA or ECDSA.

To apply JWT authentication to your routes, start by adding the auth category at the root of your configuration, and the auth.jwt sub-category:

{
  ...
  "auth": {
    "jwt": {
      "expiry": 300,
      "secret": "jwt-secret"
    }
  }
}

WARNING

Make sure your HMAC secret is securely generated and is long enough:

  • HMAC-SHA256: the secret must be 256+ bits long
  • HMAC-SHA384: the secret must be 384+ bits long
  • HMAC-SHA512: the secret must be 512+ bits long

Then, add the following middleware:

authenticator := auth.Middleware(&model.User{}, &auth.JWTAuthenticator{})
router.Middleware(authenticator)

To request a protected route, you will need to add the following header:

Authorization: Bearer <YOUR_TOKEN>
# Optional authentication

This provider supports the Optional flag, which defines if the authenticator allows requests that don't provide credentials. Handlers should therefore check if request.User is not nil before accessing it.

authenticator := auth.Middleware(&model.User{}, &auth.JWTAuthenticator{Optional: true})
router.Middleware(authenticator)
# Custom ID claim name

By default, auth.JWTAuthenticator looks for the claim named sub in the given token. You can customize the name of the token using the ClaimName field:

authenticator := auth.Middleware(&model.User{}, &auth.JWTAuthenticator{ClaimName: "userid"})
router.Middleware(authenticator)
# Claims in request.Extra

If a token is valid (even if authentication fails), its claims are put into request.Extra with the jwt_claims key, so you can access them in any subsequent handler:

import "github.com/golang-jwt/jwt"

//...

func myHandler(resp *Response, r *Request) {
	claims := request.Extra["jwt_claims"].(jwt.MapClaims)
	//...
}

# RSA

If you expect tokens to be signed with RSA, you will need to add the auth.jwt.rsa.public configuration entry. This entry defines the path to the PEM-encoded RSA public key file. Make sure the system user running your application has read access. Both absolute and relative paths are supported.

{
  ...
  "auth": {
    "jwt": {
      "expiry": 300,
      "rsa": {
		  "public": "/path/to/rsa-key.pem"
	  }
    }
  }
}

Then, specify the expected signature method in the SignatureMethod field of auth.JWTAuthenticator:

import "github.com/golang-jwt/jwt"

//...

authenticator := auth.Middleware(&model.User{}, &auth.JWTAuthenticator{SigningMethod: jwt.SigningMethodRS256})
router.Middleware(authenticator)

TIP

You can find the list of available methods in the jwt-go documentation (opens new window).

  • For testing purposes, you can generate an RSA key-pair using OpenSSL:
openssl genrsa -out rsa-private.pem 2048
openssl rsa -in rsa-private.pem -outform PEM -pubout -out rsa-public.pem

# ECDSA

If you expect tokens to be signed with ECDSA, you will need to add the auth.jwt.ecdsa.public configuration entry. This entry defines the path to the PEM-encoded ECDSA public key file. Make sure the system user running your application has read access. Both absolute and relative paths are supported.

{
  ...
  "auth": {
    "jwt": {
      "expiry": 300,
      "rsa": {
		  "public": "/path/to/ecdsa-key.pem"
	  }
    }
  }
}

Then, specify the expected signature method in the SignatureMethod field of auth.JWTAuthenticator:

import "github.com/golang-jwt/jwt"

//...

authenticator := auth.Middleware(&model.User{}, &auth.JWTAuthenticator{SigningMethod: jwt.SigningMethodES256})
router.Middleware(authenticator)

TIP

openssl ecparam -name prime256v1 -genkey -noout -out ecdsa-private.key
openssl pkcs8 -topk8 -in ecdsa-private.key -out ecdsa-private.pem
openssl ec -in ecdsa-private.pem -pubout -out ecdsa-public.pem

# Generating tokens

# auth.GenerateTokenWithClaims

Generate a new JWT with custom claims and signed using the given signing method.

The token is set to expire in the amount of seconds defined by the auth.jwt.expiry config entry.

Depending on the given signing method, the following configuration entries will be used:

  • RSA:
    • auth.jwt.rsa.private: path to the private PEM-encoded RSA key.
    • auth.jwt.rsa.password: optional password for the private RSA key.
  • ECDSA: auth.jwt.ecdsa.private: path to the private PEM-encoded ECDSA key.
  • HMAC: auth.jwt.secret: HMAC secret

The generated token will also contain the following claims:

  • nbf: "Not before", the current timestamp is used
  • exp: "Expiry", the current timestamp plus the auth.jwt.expiry config entry.

nbf and exp can be overridden if they are set in the claims parameter.

Parameters Return
claims jwt.MapClaims string
signingMethod jwt.SigningMethod error

Example:

import "github.com/golang-jwt/jwt"

//...

token, err := auth.GenerateTokenWithClaims(jwt.MapClaims{"sub": user.ID}, jwt.SigningMethodES256)
if err != nil {
	panic(err)
}
fmt.Println(token)

# auth.GenerateToken

Generate a new JWT. This function is a shortcut to auth.GenerateTokenWithClaims().

The token is created using the HMAC SHA256 method and signed using the auth.jwt.secret config entry.
The token is set to expire in the amount of seconds defined by the auth.jwt.expiry config entry.

The generated token will contain the following claims:

  • userid: has the value of the id parameter
  • nbf: "Not before", the current timestamp is used
  • exp: "Expiry", the current timestamp plus the auth.jwt.expiry config entry.
Parameters Return
id interface{} string
error

Example:

token, err := auth.GenerateToken(user.ID)
if err != nil {
	panic(err)
}
fmt.Println(token)

# JWTController

JWTAuthenticator comes with a built-in login controller for password grant, using the field tags explained earlier. You can register the /auth/login route using the helper function auth.JWTRoutes(router).

# auth.JWTRoutes

Create a /auth route group and registers the POST /auth/login validated route. Returns the new route group.

Validation rules are as follows:

  • username: required string
  • password: required string

The given model is used for username and password retrieval and for instantiating an authenticated request's user.

Ensure that the given router is not protected by JWT authentication, otherwise your users wouldn't be able to log in.

Parameters Return
router *goyave.Router *goyave.Router
model interface{}

Example:

func Register(router *goyave.Router) {
	auth.JWTRoutes(router, &model.User{})
}

# auth.NewJWTController

If you want or need to register the routes yourself, you can instantiate a new JWTController using auth.NewJWTController().

This function creates a new JWTController that will be using the given model for login and token generation.

A JWTController contains one handler called Login.

Parameters Return
model interface{} *auth.JWTController

Example:

jwtRouter := router.Subrouter("/auth")
jwtRouter.Route("POST", "/login", auth.NewJWTController(&model.User{}).Login).Validate(validation.RuleSet{
	"username": validation.List{"required", "string"},
	"password": validation.List{"required", "string"},
})

TIP

By default, the controller will use the "username" and "password" fields from incoming requests for the authentication process. This can be changed by modifying the controller's UsernameField and PasswordField structure fields:

jwtController := auth.NewJWTController(&model.User{})
jwtController.UsernameField = "email"
jwtController.PasswordField = "pwd"
# Signing method

As JWTController generates token for you, you can also customize the signing method it uses. By default, HMAC-SHA256 is used. You can override this by changing the SigningMethod field:

import "github.com/golang-jwt/jwt"

//...

jwtController := auth.NewJWTController(&model.User{})
jwtController.SigningMethod = jwt.SigningMethodES256
# Custom token generation

You can also override the token generation logic executed by the controller on successful authentication by setting the TokenFunc field:

jwtController := auth.NewJWTController(&model.User{})
jwtController.TokenFunc = func(r *goyave.Request, user interface{}) (string, error) {
	return GenerateTokenWithClaims(jwt.MapClaims{
		"sub":  user.(*model.User).ID,
		"name": user.(*model.User).Name,
	}, jwt.SigningMethodHS256)
}

TIP

auth.TokenFunc is an alias for func(request *goyave.Request, user interface{}) (string, error)

# Writing custom Authenticator

The Goyave authentication system is expandable, meaning that you can implement more authentication methods by creating a new Authenticator.

The typical Authenticator is an empty struct implementing the Authenticator interface:

type MyAuthenticator struct{}

// Ensure you're correctly implementing Authenticator.
var _ auth.Authenticator = (*MyAuthenticator)(nil) // implements Authenticator

The next step is to implement the Authenticate method. Its purpose is explained at the start of this guide.

In this example, we are going to authenticate the user using a simple token stored in the database.

func (a *MyAuthenticator) Authenticate(request *goyave.Request, user interface{}) error {
	token, ok := request.BearerToken()

	if !ok {
		return fmt.Errorf(lang.Get(request.Lang, "auth.no-credentials-provided"))
	}

	// Find the struct field tagged with `auth:"token"`
	columns := auth.FindColumns(user, "token")

	// Find the user in the database using its token
	result := database.Conn().Where(columns[0].Name+" = ?", token).First(user)

	if result.Error != nil {
		if errors.Is(result.Error, gorm.ErrRecordNotFound) {
			// User not found, return "Invalid credentials."
			return fmt.Errorf(lang.Get(request.Lang, "auth.invalid-credentials"))
		}
		// Database error
		panic(result.Error)
	}

	// Authentication successful
	return nil
}

# auth.Unauthorizer

If you need to override the default behavior when the authentication fails, you can implement the auth.Unauthorizer interface on your Authenticator.

func (a *MyAuthenticator) OnUnauthorized(response *goyave.Response, request *goyave.Request, err error) {
	response.JSON(http.StatusUnauthorized, map[string]string{"authError": err.Error()})
}

# auth.FindColumns

Find columns in the given struct. A field matches if it has a "auth" tag with the given value. Returns a slice of found fields, ordered as the input fields slice.

Promoted fields are matched as well.

If the nth field is not found, the nth value of the returned slice will be nil.

Parameters Return
struct interface{} []*auth.Column
fields ...string

Example:

Given the following struct and username, notatag, password:

type TestUser struct {
	gorm.Model
	Name     string `gorm:"type:varchar(100)"`
	Password string `gorm:"type:varchar(100)" auth:"password"`
	Email    string `gorm:"type:varchar(100);uniqueIndex" auth:"username"`
}

fields := auth.FindColumns(user, "username", "notatag", "password")

The result will be the Email field, nil and the Password field.

TIP

The Column struct is defined as follows:

type Column struct {
	Name  string
	Field *reflect.StructField
}

# Permissions

In progress

WARNING

This feature is not implemented yet and is coming in a future release.

Watch (opens new window) the github repository to stay updated.

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