Avoid federation when it is not necessary

src/api/server_server.rs

@@ -1799,6 +1799,13 @@ pub async fn get_devices_route(
         return Err(Error::bad_config("Federation is disabled."));
     }
 
+    if body.user_id.server_name() != services().globals.server_name() {
+        return Err(Error::BadRequest(
+            ErrorKind::InvalidParam,
+            "Tried to access user from other server.",
+        ));
+    }
+
     let sender_servername = body
         .sender_servername
         .as_ref()
@@ -1873,6 +1880,13 @@ pub async fn get_profile_information_route(
         return Err(Error::bad_config("Federation is disabled."));
     }
 
+    if body.user_id.server_name() != services().globals.server_name() {
+        return Err(Error::BadRequest(
+            ErrorKind::InvalidParam,
+            "Tried to access user from other server.",
+        ));
+    }
+
     let mut displayname = None;
     let mut avatar_url = None;
     let mut blurhash = None;
@@ -1909,6 +1923,17 @@ pub async fn get_keys_route(body: Ruma<get_keys::v1::Request>) -> Result<get_key
         return Err(Error::bad_config("Federation is disabled."));
     }
 
+    if body
+        .device_keys
+        .iter()
+        .any(|(u, _)| u.server_name() != services().globals.server_name())
+    {
+        return Err(Error::BadRequest(
+            ErrorKind::InvalidParam,
+            "Tried to access user from other server.",
+        ));
+    }
+
     let result = get_keys_helper(None, &body.device_keys, |u| {
         Some(u.server_name()) == body.sender_servername.as_deref()
     })
@@ -1931,6 +1956,17 @@ pub async fn claim_keys_route(
         return Err(Error::bad_config("Federation is disabled."));
     }
 
+    if body
+        .one_time_keys
+        .iter()
+        .any(|(u, _)| u.server_name() != services().globals.server_name())
+    {
+        return Err(Error::BadRequest(
+            ErrorKind::InvalidParam,
+            "Tried to access user from other server.",
+        ));
+    }
+
     let result = claim_keys_helper(&body.one_time_keys).await?;
 
     Ok(claim_keys::v1::Response {