Oidc: Properly query the UserInfo Endpoint

BooksStack's OIDC Client requests the 'profile' and 'email' scope values
in order to have access to the 'name', 'email', and other claims.  It
looks for these claims in the ID Token that is returned along with the
Access Token.

However, the OIDC-core specification section 5.4 [1] only requires that
the Provider include those claims in the ID Token *if* an Access Token is
not also issued.  If an Access Token is issued, the Provider can leave out
those claims from the ID Token, and the Client is supposed to obtain them
by submitting the Access Token to the UserInfo Endpoint.

So I suppose it's just good luck that the OIDC Providers that BookStack
has been tested with just so happen to also stick those claims in the ID
Token even though they don't have to.  But others (in particular:
https://login.infomaniak.com) don't do so, and require fetching the
UserInfo Endpoint.)

A workaround is currently possible by having the user write a theme with a
ThemeEvents::OIDC_ID_TOKEN_PRE_VALIDATE hook that fetches the UserInfo
Endpoint.  This workaround isn't great, for a few reasons:
 1. Asking the user to implement core parts of the OIDC protocol is silly.
 2. The user either needs to re-fetch the .well-known/openid-configuration
    file to discover the endpoint (adding yet another round-trip to each
    login) or hard-code the endpoint, which is fragile.
 3. The hook doesn't receive the HTTP client configuration.

So, have BookStack's OidcService fetch the UserInfo Endpoint and inject
those claims into the ID Token, if a UserInfo Endpoint is defined.
Two points about this:
 - Injecting them into the ID Token's claims is the most obvious approach
   given the current code structure; though I'm not sure it is the best
   approach, perhaps it should instead fetch the user info in
   processAuthorizationResponse() and pass that as an argument to
   processAccessTokenCallback() which would then need a bit of
   restructuring.  But this made sense because it's also how the
   ThemeEvents::OIDC_ID_TOKEN_PRE_VALIDATE hook works.
 - OIDC *requires* that a UserInfo Endpoint exists, so why bother with
   that "if a UserInfo Endpoint is defined" bit?  Simply out of an
   abundance of caution that there's an existing BookStack user that is
   relying on it not fetching the UserInfo Endpoint in order to work with
   a non-compliant OIDC Provider.

[1]: https://openid.net/specs/openid-connect-core-1_0.html#ScopeClaims

.env.example.complete

@@ -267,6 +267,7 @@ OIDC_ISSUER_DISCOVER=false
 OIDC_PUBLIC_KEY=null
 OIDC_AUTH_ENDPOINT=null
 OIDC_TOKEN_ENDPOINT=null
+OIDC_USERINFO_ENDPOINT=null
 OIDC_ADDITIONAL_SCOPES=null
 OIDC_DUMP_USER_DETAILS=false
 OIDC_USER_TO_GROUPS=false

app/Access/Oidc/OidcProviderSettings.php

@@ -22,6 +22,7 @@ class OidcProviderSettings
     public ?string $authorizationEndpoint;
     public ?string $tokenEndpoint;
     public ?string $endSessionEndpoint;
+    public ?string $userinfoEndpoint;
 
     /**
      * @var string[]|array[]
@@ -128,6 +129,10 @@ protected function loadSettingsFromIssuerDiscovery(ClientInterface $httpClient):
             $discoveredSettings['tokenEndpoint'] = $result['token_endpoint'];
         }
 
+        if (!empty($result['userinfo_endpoint'])) {
+            $discoveredSettings['userinfoEndpoint'] = $result['userinfo_endpoint'];
+        }
+
         if (!empty($result['jwks_uri'])) {
             $keys = $this->loadKeysFromUri($result['jwks_uri'], $httpClient);
             $discoveredSettings['keys'] = $this->filterKeys($keys);
@@ -177,7 +182,7 @@ protected function loadKeysFromUri(string $uri, ClientInterface $httpClient): ar
      */
     public function arrayForProvider(): array
     {
-        $settingKeys = ['clientId', 'clientSecret', 'redirectUri', 'authorizationEndpoint', 'tokenEndpoint'];
+        $settingKeys = ['clientId', 'clientSecret', 'redirectUri', 'authorizationEndpoint', 'tokenEndpoint', 'userinfoEndpoint'];
         $settings = [];
         foreach ($settingKeys as $setting) {
             $settings[$setting] = $this->$setting;

app/Access/Oidc/OidcService.php

@@ -85,6 +85,7 @@ protected function getProviderSettings(): OidcProviderSettings
             'authorizationEndpoint' => $config['authorization_endpoint'],
             'tokenEndpoint'         => $config['token_endpoint'],
             'endSessionEndpoint'    => is_string($config['end_session_endpoint']) ? $config['end_session_endpoint'] : null,
+            'userinfoEndpoint'      => $config['userinfo_endpoint'],
         ]);
 
         // Use keys if configured
@@ -228,6 +229,17 @@ protected function processAccessTokenCallback(OidcAccessToken $accessToken, Oidc
 
         session()->put("oidc_id_token", $idTokenText);
 
+        if (!empty($settings->userinfoEndpoint)) {
+            $provider = $this->getProvider($settings);
+            $request = $provider->getAuthenticatedRequest('GET', $settings->userinfoEndpoint, $accessToken->getToken());
+            $response = $provider->getParsedResponse($request);
+            $claims = $idToken->getAllClaims();
+            foreach ($response as $key => $value) {
+                $claims[$key] = $value;
+            }
+            $idToken->replaceClaims($claims);
+        }
+
         $returnClaims = Theme::dispatch(ThemeEvents::OIDC_ID_TOKEN_PRE_VALIDATE, $idToken->getAllClaims(), [
             'access_token' => $accessToken->getToken(),
             'expires_in' => $accessToken->getExpires(),

app/Config/oidc.php

@@ -35,6 +35,7 @@
     // OAuth2 endpoints.
     'authorization_endpoint' => env('OIDC_AUTH_ENDPOINT', null),
     'token_endpoint'         => env('OIDC_TOKEN_ENDPOINT', null),
+    'userinfo_endpoint'      => env('OIDC_USERINFO_ENDPOINT', null),
 
     // OIDC RP-Initiated Logout endpoint URL.
     // A false value force-disables RP-Initiated Logout.

tests/Auth/OidcTest.php

@@ -668,11 +668,44 @@ protected function withAutodiscovery()
 
     protected function runLogin($claimOverrides = []): TestResponse
     {
+        // These two variables should perhaps be arguments instead of
+        // assuming that they're tied to whether discovery is enabled,
+        // but that's how the tests are written for now.
+        $claimsInIdToken = !config('oidc.discover');
+        $tokenEndpoint = config('oidc.discover')
+                       ? OidcJwtHelper::defaultIssuer() . '/oidc/token'
+                       : 'https://oidc.local/token';
+
         $this->post('/oidc/login');
         $state = session()->get('oidc_state');
-        $this->mockHttpClient([$this->getMockAuthorizationResponse($claimOverrides)]);
 
-        return $this->get('/oidc/callback?code=SplxlOBeZQQYbYS6WxSbIA&state=' . $state);
+        $providerResponses = [$this->getMockAuthorizationResponse($claimsInIdToken ? $claimOverrides : [])];
+        if (!$claimsInIdToken) {
+            $providerResponses[] = new Response(200, [
+                'Content-Type'  => 'application/json',
+                'Cache-Control' => 'no-cache, no-store',
+                'Pragma'        => 'no-cache',
+            ], json_encode($claimOverrides));
+        }
+
+        $transactions = $this->mockHttpClient($providerResponses);
+
+        $response = $this->get('/oidc/callback?code=SplxlOBeZQQYbYS6WxSbIA&state=' . $state);
+
+        if (auth()->check()) {
+            $this->assertEquals($claimsInIdToken ? 1 : 2, $transactions->requestCount());
+            $tokenRequest = $transactions->requestAt(0);
+            $this->assertEquals($tokenEndpoint, (string) $tokenRequest->getUri());
+            $this->assertEquals('POST', $tokenRequest->getMethod());
+            if (!$claimsInIdToken) {
+                $userinfoRequest = $transactions->requestAt(1);
+                $this->assertEquals(OidcJwtHelper::defaultIssuer() . '/oidc/userinfo', (string) $userinfoRequest->getUri());
+                $this->assertEquals('GET', $userinfoRequest->getMethod());
+                $this->assertEquals('Bearer abc123', $userinfoRequest->getHeader('Authorization')[0]);
+            }
+        }
+
+        return $response;
     }
 
     protected function getAutoDiscoveryResponse($responseOverrides = []): Response
@@ -684,6 +717,7 @@ protected function getAutoDiscoveryResponse($responseOverrides = []): Response
         ], json_encode(array_merge([
             'token_endpoint'         => OidcJwtHelper::defaultIssuer() . '/oidc/token',
             'authorization_endpoint' => OidcJwtHelper::defaultIssuer() . '/oidc/authorize',
+            'userinfo_endpoint'      => OidcJwtHelper::defaultIssuer() . '/oidc/userinfo',
             'jwks_uri'               => OidcJwtHelper::defaultIssuer() . '/oidc/keys',
             'issuer'                 => OidcJwtHelper::defaultIssuer(),
             'end_session_endpoint'   => OidcJwtHelper::defaultIssuer() . '/oidc/logout',