zcash_client_backend: Track external addresses in inter-account transactions.

Previously, if the funding account for a received transaction output was
determined to be an account known to the wallet, the output was recorded
as though it were sent to an internal (change) address of the wallet.

zcash_client_backend/CHANGELOG.md

@@ -103,6 +103,8 @@ and this library adheres to Rust's notion of
     feature flag.
 - `zcash_client_backend::proto`:
   - `ProposalDecodingError` has a new variant `TransparentMemo`.
+- `zcash_client_backend::wallet::Recipient::InternalAccount` is now a structured
+  variant with an additional `external_address` field.
 - `zcash_client_backend::zip321::render::amount_str` now takes a
   `NonNegativeAmount` rather than a signed `Amount` as its argument.
 - `zcash_client_backend::zip321::parse::parse_amount` now parses a

zcash_client_backend/src/data_api/wallet.rs

@@ -1049,10 +1049,11 @@ where
                     memo.clone(),
                 )?;
                 sapling_output_meta.push((
-                    Recipient::InternalAccount(
-                        account,
-                        PoolType::Shielded(ShieldedProtocol::Sapling),
-                    ),
+                    Recipient::InternalAccount {
+                        receiving_account: account,
+                        external_address: None,
+                        note: PoolType::Shielded(ShieldedProtocol::Sapling),
+                    },
                     change_value.value(),
                     Some(memo),
                 ))
@@ -1072,10 +1073,11 @@ where
                         memo.clone(),
                     )?;
                     orchard_output_meta.push((
-                        Recipient::InternalAccount(
-                            account,
-                            PoolType::Shielded(ShieldedProtocol::Orchard),
-                        ),
+                        Recipient::InternalAccount {
+                            receiving_account: account,
+                            external_address: None,
+                            note: PoolType::Shielded(ShieldedProtocol::Orchard),
+                        },
                         change_value.value(),
                         Some(memo),
                     ))

zcash_client_backend/src/wallet.rs

@@ -2,6 +2,7 @@
 //! light client.
 
 use incrementalmerkletree::Position;
+use zcash_keys::address::Address;
 use zcash_note_encryption::EphemeralKeyBytes;
 use zcash_primitives::{
     consensus::BlockHeight,
@@ -70,7 +71,11 @@ pub enum Recipient<AccountId, N> {
     Transparent(TransparentAddress),
     Sapling(sapling::PaymentAddress),
     Unified(UnifiedAddress, PoolType),
-    InternalAccount(AccountId, N),
+    InternalAccount {
+        receiving_account: AccountId,
+        external_address: Option<Address>,
+        note: N,
+    },
 }
 
 impl<AccountId, N> Recipient<AccountId, N> {
@@ -79,7 +84,15 @@ impl<AccountId, N> Recipient<AccountId, N> {
             Recipient::Transparent(t) => Recipient::Transparent(t),
             Recipient::Sapling(s) => Recipient::Sapling(s),
             Recipient::Unified(u, p) => Recipient::Unified(u, p),
-            Recipient::InternalAccount(a, n) => Recipient::InternalAccount(a, f(n)),
+            Recipient::InternalAccount {
+                receiving_account,
+                external_address,
+                note,
+            } => Recipient::InternalAccount {
+                receiving_account,
+                external_address,
+                note: f(note),
+            },
         }
     }
 }
@@ -90,7 +103,15 @@ impl<AccountId, N> Recipient<AccountId, Option<N>> {
             Recipient::Transparent(t) => Some(Recipient::Transparent(t)),
             Recipient::Sapling(s) => Some(Recipient::Sapling(s)),
             Recipient::Unified(u, p) => Some(Recipient::Unified(u, p)),
-            Recipient::InternalAccount(a, n) => n.map(|n0| Recipient::InternalAccount(a, n0)),
+            Recipient::InternalAccount {
+                receiving_account,
+                external_address,
+                note,
+            } => note.map(|n0| Recipient::InternalAccount {
+                receiving_account,
+                external_address,
+                note: n0,
+            }),
         }
     }
 }

zcash_client_sqlite/src/lib.rs

@@ -65,6 +65,7 @@ use zcash_client_backend::{
     wallet::{Note, NoteId, ReceivedNote, Recipient, WalletTransparentOutput},
     DecryptedOutput, PoolType, ShieldedProtocol, TransferType,
 };
+use zcash_keys::address::Address;
 use zcash_primitives::{
     block::BlockHash,
     consensus::{self, BlockHeight},
@@ -1066,10 +1067,11 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                             //TODO: Recover the UA, if possible.
                             Recipient::Sapling(output.note().recipient())
                         } else {
-                            Recipient::InternalAccount(
-                                *output.account(),
-                                Note::Sapling(output.note().clone()),
-                            )
+                            Recipient::InternalAccount {
+                                receiving_account: *output.account(),
+                                external_address: None,
+                                note: Note::Sapling(output.note().clone()),
+                            }
                         };
 
                         wallet::put_sent_output(
@@ -1083,7 +1085,7 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                             Some(output.memo()),
                         )?;
 
-                        if matches!(recipient, Recipient::InternalAccount(_, _)) {
+                        if matches!(recipient, Recipient::InternalAccount { .. }) {
                             wallet::sapling::put_received_note(wdb.conn.0, output, tx_ref, None)?;
                         }
                     }
@@ -1091,11 +1093,12 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                         wallet::sapling::put_received_note(wdb.conn.0, output, tx_ref, None)?;
 
                         if let Some(account_id) = funding_account {
-                            // Even if the recipient address is external, record the send as internal.
-                            let recipient = Recipient::InternalAccount(
-                                *output.account(),
-                                Note::Sapling(output.note().clone()),
-                            );
+                            let recipient = Recipient::InternalAccount {
+                                receiving_account: *output.account(),
+                                // TODO: recover the actual UA, if possible
+                                external_address: Some(Address::Sapling(output.note().recipient())),
+                                note: Note::Sapling(output.note().clone()),
+                            };
 
                             wallet::put_sent_output(
                                 wdb.conn.0,
@@ -1128,10 +1131,11 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                                 PoolType::Shielded(ShieldedProtocol::Orchard),
                             )
                         } else {
-                            Recipient::InternalAccount(
-                                *output.account(),
-                                Note::Orchard(*output.note()),
-                            )
+                            Recipient::InternalAccount {
+                                receiving_account: *output.account(),
+                                external_address: None,
+                                note: Note::Orchard(*output.note()),
+                            }
                         };
 
                         wallet::put_sent_output(
@@ -1145,7 +1149,7 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                             Some(output.memo()),
                         )?;
 
-                        if matches!(recipient, Recipient::InternalAccount(_, _)) {
+                        if matches!(recipient, Recipient::InternalAccount { .. }) {
                             wallet::orchard::put_received_note(wdb.conn.0, output, tx_ref, None)?;
                         }
                     }
@@ -1154,10 +1158,17 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
 
                         if let Some(account_id) = funding_account {
                             // Even if the recipient address is external, record the send as internal.
-                            let recipient = Recipient::InternalAccount(
-                                *output.account(),
-                                Note::Orchard(*output.note()),
-                            );
+                            let recipient = Recipient::InternalAccount {
+                                receiving_account: *output.account(),
+                                // TODO: recover the actual UA, if possible
+                                external_address: Some(Address::Unified(
+                                    UnifiedAddress::from_receivers(
+                                    Some(output.note().recipient()),
+                                    None,
+                                    None,
+                                ).expect("UA has an Orchard receiver by construction."))),
+                                note: Note::Orchard(*output.note()),
+                            };
 
                             wallet::put_sent_output(
                                 wdb.conn.0,
@@ -1288,13 +1299,17 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                 )?;
 
                 match output.recipient() {
-                    Recipient::InternalAccount(account, Note::Sapling(note)) => {
+                    Recipient::InternalAccount {
+                        receiving_account,
+                        note: Note::Sapling(note),
+                        ..
+                    } => {
                         wallet::sapling::put_received_note(
                             wdb.conn.0,
                             &DecryptedOutput::new(
                                 output.output_index(),
                                 note.clone(),
-                                *account,
+                                *receiving_account,
                                 output
                                     .memo()
                                     .map_or_else(MemoBytes::empty, |memo| memo.clone()),
@@ -1305,13 +1320,17 @@ impl<P: consensus::Parameters> WalletWrite for WalletDb<rusqlite::Connection, P>
                         )?;
                     }
                     #[cfg(feature = "orchard")]
-                    Recipient::InternalAccount(account, Note::Orchard(note)) => {
+                    Recipient::InternalAccount {
+                        receiving_account,
+                        note: Note::Orchard(note),
+                        ..
+                    } => {
                         wallet::orchard::put_received_note(
                             wdb.conn.0,
                             &DecryptedOutput::new(
                                 output.output_index(),
                                 *note,
-                                *account,
+                                *receiving_account,
                                 output
                                     .memo()
                                     .map_or_else(MemoBytes::empty, |memo| memo.clone()),

zcash_client_sqlite/src/wallet.rs

@@ -2527,9 +2527,13 @@ fn recipient_params<P: consensus::Parameters>(
             PoolType::Shielded(ShieldedProtocol::Sapling),
         ),
         Recipient::Unified(addr, pool) => (Some(addr.encode(params)), None, *pool),
-        Recipient::InternalAccount(id, note) => (
-            None,
-            Some(id.to_owned()),
+        Recipient::InternalAccount {
+            receiving_account,
+            external_address,
+            note,
+        } => (
+            external_address.as_ref().map(|a| a.encode(params)),
+            Some(*receiving_account),
             PoolType::Shielded(note.protocol()),
         ),
     }