feat: add OIDC authentication for server mode

service/config_file.go

@@ -15,6 +15,7 @@ type fileConfig struct {
 	UserAliases []*Alias     `json:"aliases"`
 	Serve       ServerConfig `json:"serve"`
 	Remote      ServerConfig `json:"remote"`
+	OIDC        OIDCConfig   `json:"oidc"`
 }
 
 var defaultAliases = []*Alias{
@@ -142,6 +143,17 @@ func (c *fileConfig) ListAliases() ([]*Alias, error) {
 	return result, nil
 }
 
+func (c *fileConfig) GetOIDCConfig() (OIDCConfig, bool) {
+	if c.OIDC.Issuer == "" {
+		return OIDCConfig{}, false
+	}
+	cfg := c.OIDC
+	if cfg.UserClaim == "" {
+		cfg.UserClaim = "preferred_username"
+	}
+	return cfg, true
+}
+
 func (c *fileConfig) GetRemoteConfig() (ServerConfig, bool) {
 	if c.Remote.Host == "" {
 		return ServerConfig{}, false