dashboard: keys edited, the last removed with a password, failures kept

The credentials dialog listed a user's keys whole, to add one or
remove one but the last, and any failure replaced the dialog with the
error, the form lost.

* A key is shown short: its type, the first and last four characters
  of what tells it apart (an Ed25519 key's base64 after the part all of
  them share), its comment; the whole line in its tooltip.
* A key can be edited, its name and its line: saved under the name, a
  new name written first and the old one removed.
* A user with a password on this node (`--htpasswd`) may remove its
  last key: it logs in by the password. GET /auth/keys says so
  (`password`), and DELETE /auth/keys/{id} takes it then; the rules no
  longer keep the last key on every node (no other node can tell who
  has a password where; under a strict policy the signed entry keeps
  one still).
* What fails says why beside where it was asked (the add form, the
  edited row, the removed one), which stays as it was, to be set right
  and tried again.

1 files changed, 19 insertions, 7 deletions

diff --git a/src/api/users.rs b/src/api/users.rs
index 1dda33b..d6950af 100644
--- a/src/api/users.rs
+++ b/src/api/users.rs
@@ -24,8 +24,10 @@
 //! * `GET /auth/keys`: the caller's keys, its entry, and the envelope holding it under a
 //!   strict policy (`signed`), to sign the next one against.
 //! * `PUT /auth/keys/{id}`: one added or replaced (the line as the body);
-//!   `DELETE /auth/keys/{id}` removes one. Under a strict policy `409`: the user signs
-//!   its entry with the keys changed, nothing else (`continuum-signed key-add`).
+//!   `DELETE /auth/keys/{id}` removes one, the last only of a user with a password on
+//!   this node (`--htpasswd`, `password` in `GET /auth/keys`), which logs in by it. Under
+//!   a strict policy `409`: the user signs its entry with the keys changed, nothing else
+//!   (`continuum-signed key-add`).
 //!
 //! Looking needs `read` on `_continuum/users`, changing `write` on it (in a swarm
 //! without a registry, being in `--protocol-writers`). Every change is one change to
@@ -142,6 +144,7 @@ fn shown(doc: &impl crate::document::ReadDoc, name: &str) -> Option<JsonValue> {
 pub(crate) async fn own_keys(
     State(state): State<AppState>,
     Extension(user): Extension<AuthenticatedUser>,
+    Extension(auth): Extension<super::auth::AuthState>,
 ) -> Result<Json<JsonValue>, ApiError> {
     let replica = state.doc.read().await;
     let path = registry::user_path(&user.0);
@@ -157,6 +160,7 @@ pub(crate) async fn own_keys(
         "keys": entry.get("keys").cloned().unwrap_or_else(|| json!({})),
         "entry": entry,
         "signed": signed,
+        "password": auth.has_password(&user.0),
     })))
 }
 
@@ -168,24 +172,28 @@ pub(crate) async fn put_own_key(
     body: String,
 ) -> Result<StatusCode, ApiError> {
     let key = crate::access::sshsig::PublicKey::parse(body.trim()).map_err(|why| bad(&why))?;
-    own_key(&state, &user.0, id, Some(key.line())).await
+    own_key(&state, &user.0, id, Some(key.line()), false).await
 }
 
 /// `DELETE /auth/keys/{id}`.
 pub(crate) async fn delete_own_key(
     State(state): State<AppState>,
     Extension(user): Extension<AuthenticatedUser>,
+    Extension(auth): Extension<super::auth::AuthState>,
     Path(id): Path<String>,
 ) -> Result<StatusCode, ApiError> {
-    own_key(&state, &user.0, id, None).await
+    let password = auth.has_password(&user.0);
+    own_key(&state, &user.0, id, None, password).await
 }
 
-/// `user`'s key `id` set to `line`, or removed: one change, as `user`.
+/// `user`'s key `id` set to `line`, or removed: one change, as `user`. Its last key only
+/// with `password` (it has one here, and logs in by it).
 async fn own_key(
     state: &AppState,
     user: &str,
     id: String,
     line: Option<String>,
+    password: bool,
 ) -> Result<StatusCode, ApiError> {
     if !registry::valid_name(&id) {
         return Err(bad("not a key's name: 1 to 64 of A-Z a-z 0-9 . _ @ -"));
@@ -216,7 +224,7 @@ async fn own_key(
                     Some("no entry of yours".to_owned()),
                 ));
             }
-            if line.is_none() {
+            if line.is_none() && !password {
                 let mut keys = entry.clone();
                 keys.push("keys".to_owned());
                 let others = store::keys_at(&*doc, &keys)?
@@ -227,7 +235,11 @@ async fn own_key(
                 if others == 0 {
                     return Err(ApiError(
                         StatusCode::CONFLICT,
-                        Some("your last key: add another first".to_owned()),
+                        Some(
+                            "your last key, and you have no password on this node: add \
+                             another first"
+                                .to_owned(),
+                        ),
                     ));
                 }
             }