librustzcash-wrapper/src/lib.rs

@@ -1542,6 +1542,25 @@ pub extern "C" fn rust_wrapper_update_sapling_witness(
     }
 }
 
+#[no_mangle]
+pub extern "C" fn rust_wrapper_read_sapling_node(
+    cmu: *const u8,
+    cmu_len: usize,
+    out: *mut u8,
+    out_len: &mut usize
+    ){
+    let node_in: Vec<u8> = marshall_from_haskell_var(cmu, cmu_len, RW);
+    let sapling_note_comm = SaplingNoteCommitment::from_bytes(&to_array(node_in));
+    if sapling_note_comm.is_some().into() {
+        let n = Node::from_cmu(&sapling_note_comm.unwrap());
+        let h = Hhex { bytes: n.to_bytes().to_vec()};
+        marshall_to_haskell_var(&h, out, out_len, RW);
+    } else {
+        let h0 = Hhex { bytes: vec![0] };
+        marshall_to_haskell_var(&h0, out, out_len, RW);
+    }
+}
+
 #[no_mangle]
 pub extern "C" fn rust_wrapper_read_orchard_frontier(
     tree: *const u8,

src/C/Zcash.chs

@@ -246,6 +246,13 @@ import ZcashHaskell.Types
   -> `()'
 #}
 
+{# fun unsafe rust_wrapper_read_sapling_node as rustWrapperReadSaplingNode
+     { toBorshVar* `BS.ByteString'&
+     , getVarBuffer `Buffer HexString'&
+     }
+  -> `()'
+#}
+
 {# fun unsafe rust_wrapper_read_orchard_node as rustWrapperReadOrchardNode
      { toBorshVar* `BS.ByteString'&
      , getVarBuffer `Buffer HexString'&

src/ZcashHaskell/Sapling.hs

@@ -22,6 +22,7 @@ import C.Zcash
   , rustWrapperIsShielded
   , rustWrapperReadSaplingCommitmentTree
   , rustWrapperReadSaplingFrontier
+  , rustWrapperReadSaplingNode
   , rustWrapperReadSaplingPosition
   , rustWrapperReadSaplingWitness
   , rustWrapperSaplingCheck
@@ -185,6 +186,14 @@ genSaplingInternalAddress sk =
     res =
       withPureBorshVarBuffer (rustWrapperSaplingChgPaymentAddress $ getBytes sk)
 
+getSaplingNodeValue :: BS.ByteString -> Maybe HexString
+getSaplingNodeValue cmu =
+  if BS.length (hexBytes n) > 1
+    then Just n
+    else Nothing
+  where
+    n = withPureBorshVarBuffer $ rustWrapperReadSaplingNode cmu
+
 getSaplingFrontier :: SaplingCommitmentTree -> Maybe SaplingFrontier
 getSaplingFrontier tree =
   if sf_pos updatedTree > 1