empty namespace table implies empty block payload, with tests

EspressoSystems · Jun 26, 2024 · a0eb396 · a0eb396
1 parent 50c2abc
commit a0eb396
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Showing 2 changed files with 30 additions and 4 deletions.
diff --git a/sequencer/src/block/full_payload/ns_table.rs b/sequencer/src/block/full_payload/ns_table.rs
@@ -221,10 +221,11 @@ impl NsTable {
     /// 1. Byte length must hold a whole number of entries.
     /// 2. All namespace IDs and offsets must increase monotonically. Offsets
     ///    must be nonzero.
-    /// 3. Header consistent with byte length (obsolete after
-    ///    <https://github.com/EspressoSystems/espresso-sequencer/issues/1604>)
-    /// 4. Final offset must equal `payload_byte_len` (obsolete after
-    ///    <https://github.com/EspressoSystems/espresso-sequencer/issues/1604>)
+    /// 3. Header consistent with byte length. (Obsolete after
+    ///    <https://github.com/EspressoSystems/espresso-sequencer/issues/1604>.)
+    /// 4. Final offset must equal `payload_byte_len`. (Obsolete after
+    ///    <https://github.com/EspressoSystems/espresso-sequencer/issues/1604>.)
+    ///    If the namespace table is empty then `payload_byte_len` must be 0.
     pub fn validate(
         &self,
         payload_byte_len: &PayloadByteLen,
@@ -242,6 +243,8 @@ impl NsTable {
             if final_offset != payload_byte_len.as_usize() {
                 return Err(InvalidFinalOffset);
             }
+        } else if payload_byte_len.as_usize() != 0 {
+            return Err(ExpectNonemptyNsTable);
         }
 
         Ok(())
@@ -372,6 +375,7 @@ pub enum NsTableValidationError {
     NonIncreasingEntries,
     InvalidHeader, // TODO this variant obsolete after https://github.com/EspressoSystems/espresso-sequencer/issues/1604
     InvalidFinalOffset, // TODO this variant obsolete after https://github.com/EspressoSystems/espresso-sequencer/issues/1604
+    ExpectNonemptyNsTable,
 }
 
 pub struct NsTableBuilder {

diff --git a/sequencer/src/block/full_payload/ns_table/test.rs b/sequencer/src/block/full_payload/ns_table/test.rs
@@ -101,6 +101,28 @@ async fn payload_byte_len() {
 
     // final offset less than payload byte len
     modify_final_offset(-1);
+
+    // zero-length payload
+    let empty_block = Payload::from_transactions([], &Default::default(), &Default::default())
+        .await
+        .unwrap()
+        .0;
+    assert_eq!(empty_block.ns_table().len().0, 0);
+    assert_eq!(
+        empty_block.ns_table().bytes,
+        usize_to_bytes::<NUM_NSS_BYTE_LEN>(0)
+    );
+    empty_block
+        .ns_table()
+        .validate(&empty_block.byte_len())
+        .unwrap();
+
+    // empty namespace table with nonempty payload
+    *block.ns_table_mut() = empty_block.ns_table().clone();
+    assert_eq!(
+        block.ns_table().validate(&payload_byte_len).unwrap_err(),
+        ExpectNonemptyNsTable
+    );
 }
 
 #[test]