Use simple BTreeMap to store uiaa requests

some uiaa requests contain plaintext passwords which should never be
persisted to disk.

Currently there is no cleanup implemented (you have to restart conduit)

src/database.rs

@@ -250,8 +250,7 @@ impl Database {
             },
             uiaa: uiaa::Uiaa {
                 userdevicesessionid_uiaainfo: builder.open_tree("userdevicesessionid_uiaainfo")?,
-                userdevicesessionid_uiaarequest: builder
+                userdevicesessionid_uiaarequest: RwLock::new(BTreeMap::new()),
-                    .open_tree("userdevicesessionid_uiaarequest")?,
             },
             rooms: rooms::Rooms {
                 edus: rooms::RoomEdus {

src/database/uiaa.rs

@@ -1,4 +1,6 @@
 use std::sync::Arc;
+use std::sync::RwLock;
+use std::collections::BTreeMap;
 
 use crate::{client_server::SESSION_ID_LENGTH, utils, Error, Result};
 use ruma::{
@@ -18,7 +20,7 @@ use super::abstraction::Tree;
 
 pub struct Uiaa {
     pub(super) userdevicesessionid_uiaainfo: Arc<dyn Tree>, // User-interactive authentication
-    pub(super) userdevicesessionid_uiaarequest: Arc<dyn Tree>, // UiaaRequest = canonical json value
+    pub(super) userdevicesessionid_uiaarequest: RwLock<BTreeMap<Vec<u8>, Vec<u8>>>, // UiaaRequest = canonical json value
 }
 
 impl Uiaa {
@@ -153,10 +155,10 @@ impl Uiaa {
         userdevicesessionid.push(0xff);
         userdevicesessionid.extend_from_slice(session.as_bytes());
 
-        self.userdevicesessionid_uiaarequest.insert(
+        self.userdevicesessionid_uiaarequest.write().unwrap().insert(
-            &userdevicesessionid,
+            userdevicesessionid,
-            &serde_json::to_vec(request).expect("json value to vec always works"),
+            serde_json::to_vec(request).expect("json value to vec always works"),
-        )?;
+        );
 
         Ok(())
     }
@@ -173,8 +175,8 @@ impl Uiaa {
         userdevicesessionid.push(0xff);
         userdevicesessionid.extend_from_slice(session.as_bytes());
 
-        self.userdevicesessionid_uiaarequest
+        self.userdevicesessionid_uiaarequest.read().unwrap()
-            .get(&userdevicesessionid)?
+            .get(&userdevicesessionid)
             .map(|bytes| {
                 serde_json::from_str::<CanonicalJsonValue>(
                     &utils::string_from_bytes(&bytes)