add change output to unspent/received notes

zcash_extras/src/wallet.rs

@@ -2,23 +2,62 @@
 use std::fmt::{Debug, Display};
 
 use zcash_primitives::{
-    consensus::{self, BranchId},
+    consensus::{self, BranchId, NetworkUpgrade},
     memo::MemoBytes,
     sapling::prover::TxProver,
     transaction::{
         builder::Builder,
         components::{amount::DEFAULT_FEE, Amount},
+        Transaction,
     },
     zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
 };
 
 use crate::WalletWrite;
 use zcash_client_backend::{
     address::RecipientAddress,
-    data_api::{error::Error, SentTransaction},
+    data_api::{error::Error, ReceivedTransaction, SentTransaction},
+    decrypt_transaction,
     wallet::{AccountId, OvkPolicy},
 };
 
+/// Scans a [`Transaction`] for any information that can be decrypted by the accounts in
+/// the wallet, and saves it to the wallet.
+pub async fn decrypt_and_store_transaction<N, E, P, D>(
+    params: &P,
+    data: &mut D,
+    tx: &Transaction,
+) -> Result<(), E>
+where
+    E: From<Error<N>>,
+    P: consensus::Parameters,
+    D: WalletWrite<Error = E>,
+{
+    // Fetch the ExtendedFullViewingKeys we are tracking
+    let extfvks = data.get_extended_full_viewing_keys().await?;
+
+    let max_height = data.block_height_extrema().await?.map(|(_, max)| max + 1);
+    let height = data
+        .get_tx_height(tx.txid())
+        .await?
+        .or(max_height)
+        .or_else(|| params.activation_height(NetworkUpgrade::Sapling))
+        .ok_or(Error::SaplingNotActive)?;
+
+    let outputs = decrypt_transaction(params, height, tx, &extfvks);
+    if outputs.is_empty() {
+        Ok(())
+    } else {
+        data.store_received_tx(&ReceivedTransaction {
+            tx,
+            outputs: &outputs,
+        })
+        .await?;
+
+        Ok(())
+    }
+}
+
 #[allow(clippy::needless_doctest_main)]
 /// Creates a transaction paying the specified address from the given account.
 ///
@@ -182,8 +221,7 @@ where
         RecipientAddress::Shielded(to) => {
             builder.add_sapling_output(ovk, to.clone(), value, memo.clone())
         }
-
-        RecipientAddress::Transparent(to) => builder.add_transparent_output(&to, value),
+        RecipientAddress::Transparent(to) => builder.add_transparent_output(to, value),
     }
     .map_err(Error::Builder)?;
 
@@ -209,6 +247,11 @@ where
         }
     };
 
+    // Automatically decrypt and store any outputs sent to our wallet, including change.
+    // This uses our viewing keys to find any outputs we can decrypt, creates decrypted
+    // note data for spendability, and saves them to the wallet database.
+    decrypt_and_store_transaction(params, wallet_db, &tx).await?;
+
     wallet_db
         .store_sent_tx(&SentTransaction {
             tx: &tx,

zcash_primitives/src/transaction/builder.rs

@@ -634,7 +634,6 @@ impl<'a, P: consensus::Parameters, R: RngCore> Builder<'a, P, R> {
         // Change output
         //
 
-        /*
         if change.is_positive() {
             // Send change to the specified change address. If no change address
             // was set, send change to the first Sapling address given as input.
@@ -655,7 +654,6 @@ impl<'a, P: consensus::Parameters, R: RngCore> Builder<'a, P, R> {
 
             self.add_sapling_output(Some(change_address.0), change_address.1, change, None)?;
         }
-        */
 
         //
         // Record initial positions of spends and outputs