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https://github.com/xenitab/go-oidc-middleware

OpenID Connect (OIDC) http middleware for Go
https://github.com/xenitab/go-oidc-middleware

hacktoberfest oidc openid-connect

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OpenID Connect (OIDC) http middleware for Go

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# Go OpenID Connect (OIDC) HTTP Middleware

[![Coverage Status](https://coveralls.io/repos/github/XenitAB/go-oidc-middleware/badge.svg)](https://coveralls.io/github/XenitAB/go-oidc-middleware)

## Introduction

This is a middleware for http to make it easy to use OpenID Connect.

## Changelog

Below, large (breaking) changes will be documented:

### v0.0.42

Error handlers now have access to the request and have full control over the HTTP response sent to the client. Among other things, this can be used to return structured error responses a la [RFC7807](https://datatracker.ietf.org/doc/html/rfc7807). However, this comes with a breaking interface change: error handler contract changes from `type ErrorHandler func(description ErrorDescription, err error)` to `errorHandler(ctx context.Context, oidcErr *options.OidcError) *options.Response`. To retain the behavior of your error handler, update your error handler signature accordingly, change `description` to `oidcErr.Status`, `err` to `oidcErr.Error` and add an explicit `return nil`.

### v0.0.41

The `oidcechojwt` adapter is replaced by `oidcecho` which brings in line with the other adapters in that it operates as a ordinary middleware. This makes all adapters full HTTP middlewares. That makes it easier to add new features, such as the the upcoming error handling changes. The new adapter provides identical features.

### v0.0.37

From `v0.0.37` and forward, the `options.WithRequiredClaims()` has been deprecated and generics are used to provide the claims type. A new validation function can be provided instead of `options.WithRequiredClaims()`. If you don't need claims validation, you can pass `nil` instead of a `ClaimsValidationFn`.

## Stability notice

This library is under active development and the api will have breaking changes until `v0.1.0` - after that only breaking changes will be introduced between minor versions (`v0.1.0` -> `v0.2.0`).

## Currently tested providers

- Azure AD
- Auth0
- Okta
- Cognito

## Currently Supported frameworks

- [net/http](https://pkg.go.dev/net/http), [mux](https://github.com/gorilla/mux) & [chi](https://github.com/go-chi/chi)
- [gin](https://github.com/gin-gonic/gin)
- [fiber](https://github.com/gofiber/fiber)
- [Echo](https://echo.labstack.com/)
- Build your own middleware

### Using options

Import: `"github.com/xenitab/go-oidc-middleware/options"`

### Claims validation example

From `v0.0.37` and forward, claim validation is done using a `ClaimsValidationFn`. The below examples will use the following claims type and validation function:

```go
type AzureADClaims struct {
Aio string `json:"aio"`
Audience []string `json:"aud"`
Azp string `json:"azp"`
Azpacr string `json:"azpacr"`
ExpiresAt time.Time `json:"exp"`
IssuedAt time.Time `json:"iat"`
Idp string `json:"idp"`
Issuer string `json:"iss"`
Name string `json:"name"`
NotBefore time.Time `json:"nbf"`
Oid string `json:"oid"`
PreferredUsername string `json:"preferred_username"`
Rh string `json:"rh"`
Scope string `json:"scp"`
Subject string `json:"sub"`
TenantId string `json:"tid"`
Uti string `json:"uti"`
TokenVersion string `json:"ver"`
}

func GetAzureADClaimsValidationFn(requiredTenantId string) options.ClaimsValidationFn[AzureADClaims] {
return func(claims *AzureADClaims) error {
if requiredTenantId != "" && claims.TenantId != requiredTenantId {
return fmt.Errorf("tid claim is required to be %q but was: %s", requiredTenantId, claims.TenantId)
}

return nil
}
}
```

If you don't want typed claims, use `type Claims map[string]interface{}` and provide it. If you don't want to use a `ClaimsValidationFn` (as it will provide the type) the handlers will need to be configured as below:

```go
type Claims map[string]interface{}

oidcHandler := oidchttp.New[Claims](h, nil, opts...)
```

or

```go
oidcHandler := oidchttp.New[map[string]interface{}](h, nil, opts...)
```

### net/http, mux & chi

**Import**

`"github.com/xenitab/go-oidc-middleware/oidchttp"`

**Middleware**

```go
oidcHandler := oidchttp.New(h,
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithRequiredTokenType("JWT"),
options.WithRequiredAudience(cfg.Audience),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
)
```

**Handler**

```go
func newClaimsHandler() http.HandlerFunc {
fn := func(w http.ResponseWriter, r *http.Request) {
claims, ok := r.Context().Value(options.DefaultClaimsContextKeyName).(AzureADClaims)
if !ok {
w.WriteHeader(http.StatusUnauthorized)
return
}

w.Header().Set("Content-Type", "application/json")
err := json.NewEncoder(w).Encode(claims)
if err != nil {
w.WriteHeader(http.StatusInternalServerError)
return
}
}

return http.HandlerFunc(fn)
}
```

### gin

**Import**

`"github.com/xenitab/go-oidc-middleware/oidcgin"`

**Middleware**

```go
oidcHandler := oidcgin.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithRequiredTokenType("JWT"),
options.WithRequiredAudience(cfg.Audience),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
)
```

**Handler**

```go
func newClaimsHandler() gin.HandlerFunc {
return func(c *gin.Context) {
claimsValue, found := c.Get("claims")
if !found {
c.AbortWithStatus(http.StatusUnauthorized)
return
}

claims, ok := claimsValue.(AzureADClaims)
if !ok {
c.AbortWithStatus(http.StatusUnauthorized)
return
}

c.JSON(http.StatusOK, claims)
}
}
```

### fiber

**Import**

`"github.com/xenitab/go-oidc-middleware/oidcfiber"`

**Middleware**

```go
oidcHandler := oidcfiber.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithRequiredTokenType("JWT"),
options.WithRequiredAudience(cfg.Audience),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
)
```

**Handler**

```go
func newClaimsHandler() fiber.Handler {
return func(c *fiber.Ctx) error {
claims, ok := c.Locals("claims").(AzureADClaims)
if !ok {
return c.SendStatus(fiber.StatusUnauthorized)
}

return c.JSON(claims)
}
}
```

### Echo

**Import**

`"github.com/xenitab/go-oidc-middleware/oidcecho"`

**Middleware**

```go
oidcHandler := oidcecho.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithRequiredTokenType("JWT"),
options.WithRequiredAudience(cfg.Audience),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
)
```

**Handler**

```go
func newClaimsHandler(c echo.Context) error {
claims, ok := c.Get("user").(AzureADClaims)
if !ok {
return echo.NewHTTPError(http.StatusUnauthorized, "invalid token")
}

return c.JSON(http.StatusOK, claims)
}
```

### Build your own middleware

**Import**

`"github.com/xenitab/go-oidc-middleware/oidctoken"`

**Example**

```go
oidcTokenHandler := oidctoken.New(h,
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithRequiredTokenType("JWT"),
options.WithRequiredAudience(cfg.Audience),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
)

// oidctoken.GetTokenString is optional, but you will need the JWT token as a string
tokenString, err := oidctoken.GetTokenString(...)
if err != nil {
panic(err)
}

token, err := oidcTokenHandler.ParseToken(ctx, tokenString)
if err != nil {
panic(err)
}
```

## Other options

### Extract token from multiple headers

Example for `Authorization` and `Foo` headers. If token is found in `Authorization`, `Foo` will not be tried. If `Authorization` extraction fails but there's a header `Foo = Bar_baz` then `baz` would be extracted as the token.

```go
oidcHandler := oidcgin.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
options.WithTokenString(
options.WithTokenStringHeaderName("Authorization"),
options.WithTokenStringTokenPrefix("Bearer "),
),
options.WithTokenString(
options.WithTokenStringHeaderName("Foo"),
options.WithTokenStringTokenPrefix("Bar_"),
),
)
```

### Manipulate the token string after extraction

If you want to do any kind of manipulation of the token string after extraction, the option `WithTokenStringPostExtractionFn` is available.

The following would be used by a the Kubernetes api server, where the kubernetes client can use both `Authorization` and `Sec-WebSocket-Protocol`.

```go
oidcHandler := oidcgin.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
options.WithTokenString(
options.WithTokenStringHeaderName("Authorization"),
options.WithTokenStringTokenPrefix("Bearer "),
),
options.WithTokenString(
options.WithTokenStringHeaderName("Sec-WebSocket-Protocol"),
options.WithTokenStringTokenPrefix("base64url.bearer.authorization.k8s.io."),
options.WithTokenStringListSeparator(","),
options.WithTokenStringPostExtractionFn(func(s string) (string, error) {
bytes, err := base64.RawStdEncoding.DecodeString(s)
if err != nil {
return "", err
}

return string(bytes), nil
}),
),
)
```

### Custom error handler

It is possible to add a custom function to handle errors. The error handler can return an `options.Response` which will be rendered by the middleware. Returning `nil` will result in a default 400/401 error.

```go
type Message struct {
Message string `json:"message"`
Url string `json:"url"`
}

func errorHandler(ctx context.Context, oidcErr *options.OidcError) *options.Response {
message := Message{
Message: string(oidcErr.Status),
Url: oidcErr.Url.String(),
}
var headers map[string]string
json, err := json.Marshal(message)
if err != nil {
headers["Content-Type"] = "text/plain"
return &options.Response{
StatusCode: 500,
Headers: headers,
Body: []byte("Internal encoding failure\r\n"),
}
}
headers["Content-Type"] = "text/plain"
return &options.Response{
StatusCode: 418,
Headers: headers,
Body: json,
}
}

oidcHandler := oidcgin.New(
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(cfg.Issuer),
options.WithFallbackSignatureAlgorithm(cfg.FallbackSignatureAlgorithm),
options.WithErrorHandler(errorHandler),
)
```

This error handling interface was changed in v0.0.42. The previous interface was `func(description ErrorDescription, err error)`. In order to retain the same behavior, you need to update your error handler to read `desctiption` and `err` from `oidcErr` and return `nil`.

### Testing with the middleware enabled

There's a small package that simulates an OpenID Provider that can be used with tests.

```go
package main

import (
"testing"

"github.com/xenitab/go-oidc-middleware/optest"
)

func TestFoobar(t *testing.T) {
op := optest.NewTesting(t)
defer op.Close(t)

[...]

oidcHandler := oidchttp.New(h,
GetAzureADClaimsValidationFn(cfg.TenantID),
options.WithIssuer(op.GetURL(t)),
options.WithRequiredTokenType("JWT+AT"),
options.WithRequiredAudience("test-client"),
)

token := op.GetToken(t)

[...]

token.SetAuthHeader(req)

[...]
}
```

You can also configure multiple users by setting the following:

```go
func TestFoobar(t *testing.T) {
testUsers := map[string]TestUser{
"test": {
Audience: "test-client",
Subject: "test",
Name: "Test Testersson",
GivenName: "Test",
FamilyName: "Testersson",
Locale: "en-US",
Email: "[email protected]",
AccessTokenKeyType: "JWT+AT",
IdTokenKeyType: "JWT",
},
"foo": {
Audience: "foo-client",
Subject: "foo",
Name: "Foo Bar",
GivenName: "Foo",
FamilyName: "Bar",
Locale: "en-US",
Email: "[email protected]",
AccessTokenKeyType: "JWT+AT",
IdTokenKeyType: "JWT",
},
}

op := optest.NewTesting(t, optest.WithTestUsers(testUsers), optest.WithDefaultTestUser("test"))
defer op.Close(t)

[...]

token1 := op.GetToken(t) // for user `test`
token2 := op.GetTokenByUser(t, "test") // for user `test`
token3 := op.GetTokenByUser(t, "foo") // for user `foo`
}
```

It is also possible to enable opaque access tokens with the option `optest.WithOpaqueAccessTokens()`. If you add `optest.WithLoginPrompt()` you will have a simple HTML page with the different test users to choose from when going to `/authorization`.

## Examples

See [examples readme](examples/README.md) for more information.

## Roadmap

[GitHub Project](https://github.com/XenitAB/go-oidc-middleware/projects/1)