fix unmarshaling of key inside of oauth metadata (#27)

oauth/client/manager.go

···
 	}
 
 	var jwks jwk.Key
-	if metadata.JWKS != nil {
+	if metadata.JWKS != nil && len(metadata.JWKS.Keys) > 0 {
 		// TODO: this is kinda bad but whatever for now. there could obviously be more than one jwk, and we need to
 		// make sure we use the right one
-		k, err := helpers.ParseJWKFromBytes((*metadata.JWKS)[0])
+		b, err := json.Marshal(metadata.JWKS.Keys[0])
 		if err != nil {
 			return nil, err
 		}
+
+		k, err := helpers.ParseJWKFromBytes(b)
+		if err != nil {
+			return nil, err
+		}
+
 		jwks = k
 	} else if metadata.JWKSURI != nil {
 		maybeJwks, err := cm.getClientJwks(ctx, clientId, *metadata.JWKSURI)
···
 		}
 
 		jwks = maybeJwks
+	} else {
+		return nil, fmt.Errorf("no valid jwks found in oauth client metadata")
 	}
 
 	return &Client{
···
 			return nil, errors.New("private_key_jwt auth method requires jwks or jwks_uri")
 		}
 
-		if metadata.JWKS != nil && len(*metadata.JWKS) == 0 {
+		if metadata.JWKS != nil && len(metadata.JWKS.Keys) == 0 {
 			return nil, errors.New("private_key_jwt auth method requires atleast one key in jwks")
 		}
 

oauth/client/metadata.go

···
 package client
 
 type Metadata struct {
-	ClientID                    string    `json:"client_id"`
-	ClientName                  string    `json:"client_name"`
-	ClientURI                   string    `json:"client_uri"`
-	LogoURI                     string    `json:"logo_uri"`
-	TOSURI                      string    `json:"tos_uri"`
-	PolicyURI                   string    `json:"policy_uri"`
-	RedirectURIs                []string  `json:"redirect_uris"`
-	GrantTypes                  []string  `json:"grant_types"`
-	ResponseTypes               []string  `json:"response_types"`
-	ApplicationType             string    `json:"application_type"`
-	DpopBoundAccessTokens       bool      `json:"dpop_bound_access_tokens"`
-	JWKSURI                     *string   `json:"jwks_uri,omitempty"`
-	JWKS                        *[][]byte `json:"jwks,omitempty"`
-	Scope                       string    `json:"scope"`
-	TokenEndpointAuthMethod     string    `json:"token_endpoint_auth_method"`
-	TokenEndpointAuthSigningAlg string    `json:"token_endpoint_auth_signing_alg"`
+	ClientID                    string        `json:"client_id"`
+	ClientName                  string        `json:"client_name"`
+	ClientURI                   string        `json:"client_uri"`
+	LogoURI                     string        `json:"logo_uri"`
+	TOSURI                      string        `json:"tos_uri"`
+	PolicyURI                   string        `json:"policy_uri"`
+	RedirectURIs                []string      `json:"redirect_uris"`
+	GrantTypes                  []string      `json:"grant_types"`
+	ResponseTypes               []string      `json:"response_types"`
+	ApplicationType             string        `json:"application_type"`
+	DpopBoundAccessTokens       bool          `json:"dpop_bound_access_tokens"`
+	JWKSURI                     *string       `json:"jwks_uri,omitempty"`
+	JWKS                        *MetadataJwks `json:"jwks,omitempty"`
+	Scope                       string        `json:"scope"`
+	TokenEndpointAuthMethod     string        `json:"token_endpoint_auth_method"`
+	TokenEndpointAuthSigningAlg string        `json:"token_endpoint_auth_signing_alg"`
+}
+
+type MetadataJwks struct {
+	Keys []any `json:"keys"`
 }