users: a user can't remove its own last key

A user managing its own keys (1168) could remove the last, and then
neither sign nor log in by key. It can't now: DELETE /auth/keys/{id}
of the last answers 409, the rules take a user's change of its own keys
only with one left after it, and under a strict policy its own entry
signed only with one key at least. One who may manage users still may.

1 files changed, 16 insertions, 0 deletions

diff --git a/src/api/users.rs b/src/api/users.rs
index 122fc4b..1dda33b 100644
--- a/src/api/users.rs
+++ b/src/api/users.rs
@@ -197,6 +197,7 @@ async fn own_key(
     let mut path = entry.clone();
     path.extend(["keys".to_owned(), id.clone()]);
     let adding = line.is_some();
+    let id_kept = id.clone();
     state
         .mutate_doc_for(Some(user.to_owned()), Sign::Protocol, move |doc| {
             if crate::access::policy::of(&*doc).strict() {
@@ -215,6 +216,21 @@ async fn own_key(
                     Some("no entry of yours".to_owned()),
                 ));
             }
+            if line.is_none() {
+                let mut keys = entry.clone();
+                keys.push("keys".to_owned());
+                let others = store::keys_at(&*doc, &keys)?
+                    .unwrap_or_default()
+                    .into_iter()
+                    .filter(|other| *other != id_kept)
+                    .count();
+                if others == 0 {
+                    return Err(ApiError(
+                        StatusCode::CONFLICT,
+                        Some("your last key: add another first".to_owned()),
+                    ));
+                }
+            }
             match line {
                 Some(line) => store::write_path(doc, &path, &json!(line))?,
                 None => match store::delete_path(doc, &path, false) {