swarm: unrestricted_internet flag on the agent permissions record, unset reads as on, create writes false

swarm-queue-client/src/agent_permissions.rs

@@ -50,6 +50,15 @@ pub fn held(record: &AgentPermissions) -> Vec<hive_types::Permission> {
         .unwrap_or_else(|| hive_types::Permission::DEFAULT.to_vec())
 }
 
+/// Whether `record` lets the agent's traffic leave unfiltered: its flag when
+/// set, **on** when absent. A record written before the flag existed, or a
+/// missing key, is an agent that has always had open access.
+#[cfg(feature = "agent-permissions")]
+#[must_use]
+pub fn unrestricted(record: &AgentPermissions) -> bool {
+    record.unrestricted_internet.unwrap_or(true)
+}
+
 /// Read `agent`'s current permissions with one direct get: the one subject
 /// an agent's own grant covers, and one of those a hive's covers.
 ///
@@ -129,6 +138,35 @@ mod tests {
         );
     }
 
+    /// An absent flag reads on, and so does a missing or deleted key; only an
+    /// explicit `false` reads off.
+    #[test]
+    fn an_absent_internet_flag_reads_on() {
+        let record = |json: &str| -> AgentPermissions { serde_json::from_str(json).unwrap() };
+        assert!(unrestricted(&record("{}")));
+        assert!(unrestricted(&record(r#"{"permissions":[]}"#)));
+        assert!(unrestricted(&record(r#"{"unrestricted_internet":true}"#)));
+        assert!(!unrestricted(&record(r#"{"unrestricted_internet":false}"#)));
+        assert!(unrestricted(&decode(Some("DEL"), b"").unwrap()));
+    }
+
+    /// A decoder built before the flag existed has no such field and ignores
+    /// unknown ones; it reads a record carrying the flag.
+    #[test]
+    fn a_decoder_without_the_flag_tolerates_it() {
+        #[derive(serde::Deserialize)]
+        struct Old {
+            permissions: Option<Vec<hive_types::Permission>>,
+        }
+        let old: Old =
+            serde_json::from_str(r#"{"permissions":["web_tools"],"unrestricted_internet":false}"#)
+                .unwrap();
+        assert_eq!(
+            old.permissions,
+            Some(vec![hive_types::Permission::WebTools])
+        );
+    }
+
     /// Fields a newer controller adds must not cost an older hive the ones it
     /// knows; a deleted key is unset.
     #[cfg(feature = "agent-permissions")]