Documented U2F, removed debug prints, and documented missing features

src/api/identity.rs

@@ -14,6 +14,8 @@ use util::{self, JsonMap};
 
 use api::{ApiResult, JsonResult};
 
+use CONFIG;
+
 pub fn routes() -> Vec<Route> {
     routes![login]
 }
@@ -216,7 +218,7 @@ fn _json_err_twofactor(providers: &[i32], user_uuid: &str, conn: &DbConn) -> Api
         match TwoFactorType::from_i32(*provider) {
             Some(TwoFactorType::Authenticator) => { /* Nothing to do for TOTP */ }
 
-            Some(TwoFactorType::U2f) => {
+            Some(TwoFactorType::U2f) if CONFIG.domain_set => {
                 let request = two_factor::generate_u2f_login(user_uuid, conn)?;
                 let mut challenge_list = Vec::new();