feat: support add additional params for OIDC (#2814)

* feat: support add additional params and test access by auth0

* fix: config name

Co-authored-by: blizard863 <760076784@qq.com>

conf/frpc_full.ini

@@ -51,6 +51,12 @@ oidc_audience =
 # It will be used to get an OIDC token if AuthenticationMethod == "oidc". By default, this value is "".
 oidc_token_endpoint_url =
 
+# oidc_additional_xxx specifies additional parameters to be sent to the OIDC Token Endpoint.
+# For example, if you want to specify the "audience" parameter, you can set as follow.
+# frp will add "audience=<value>" "var1=<value>" to the additional parameters.
+# oidc_additional_audience = https://dev.auth.com/api/v2/
+# oidc_additional_var1 = foobar
+
 # set admin address for control frpc's action by http api such as reload
 admin_addr = 127.0.0.1
 admin_port = 7400

pkg/auth/oidc.go

@@ -40,6 +40,11 @@ type OidcClientConfig struct {
 	// It will be used to get an OIDC token if AuthenticationMethod == "oidc".
 	// By default, this value is "".
 	OidcTokenEndpointURL string `ini:"oidc_token_endpoint_url" json:"oidc_token_endpoint_url"`
+
+	// OidcAdditionalEndpointParams specifies additional parameters to be sent
+	// this field will be transfer to map[string][]string in OIDC token generator
+	// The field will be set by prefix "oidc_additional_"
+	OidcAdditionalEndpointParams map[string]string `ini:"-" json:"oidc_additional_endpoint_params"`
 }
 
 func getDefaultOidcClientConf() OidcClientConfig {
@@ -48,6 +53,7 @@ func getDefaultOidcClientConf() OidcClientConfig {
 		OidcClientSecret:             "",
 		OidcAudience:                 "",
 		OidcTokenEndpointURL:         "",
+		OidcAdditionalEndpointParams: make(map[string]string),
 	}
 }
 
@@ -88,11 +94,17 @@ type OidcAuthProvider struct {
 }
 
 func NewOidcAuthSetter(baseCfg BaseConfig, cfg OidcClientConfig) *OidcAuthProvider {
+	eps := make(map[string][]string)
+	for k, v := range cfg.OidcAdditionalEndpointParams {
+		eps[k] = []string{v}
+	}
+
 	tokenGenerator := &clientcredentials.Config{
 		ClientID:       cfg.OidcClientID,
 		ClientSecret:   cfg.OidcClientSecret,
 		Scopes:         []string{cfg.OidcAudience},
 		TokenURL:       cfg.OidcTokenEndpointURL,
+		EndpointParams: eps,
 	}
 
 	return &OidcAuthProvider{

pkg/config/client.go

@@ -261,6 +261,8 @@ func UnmarshalClientConfFromIni(source interface{}) (ClientCommonConf, error) {
 	}
 
 	common.Metas = GetMapWithoutPrefix(s.KeysHash(), "meta_")
+	common.ClientConfig.OidcAdditionalEndpointParams = GetMapWithoutPrefix(s.KeysHash(), "oidc_additional_")
+
 	return common, nil
 }