Add watch-only support to Zcash RPC methods

Balance totals do not include spends linked to viewing key addresses, as
nullifiers cannot be calculated and therefore spends cannot be detected.

qa/rpc-tests/wallet_nullifiers.py

@@ -170,5 +170,50 @@ class WalletNullifiersTest (BitcoinTestFramework):
         assert_equal(self.nodes[1].z_getbalance(myzaddr), zaddrremaining2)
         assert_equal(self.nodes[2].z_getbalance(myzaddr), zaddrremaining2)
 
+        # Test viewing keys
+
+        node3mined = Decimal('250.0')
+        assert_equal({k: Decimal(v) for k, v in self.nodes[3].z_gettotalbalance().items()}, {
+            'transparent': node3mined,
+            'private': zsendmany2notevalue,
+            'total': node3mined + zsendmany2notevalue,
+        })
+
+        # add node 1 address and node 2 viewing key to node 3
+        myzvkey = self.nodes[2].z_exportviewingkey(myzaddr)
+        self.nodes[3].importaddress(mytaddr1)
+        self.nodes[3].z_importviewingkey(myzvkey)
+
+        # Check the address has been imported
+        assert_equal(myzaddr in self.nodes[3].z_listaddresses(), False)
+        assert_equal(myzaddr in self.nodes[3].z_listaddresses(True), True)
+
+        # Node 3 should see the same received notes as node 2
+        assert_equal(
+            self.nodes[2].z_listreceivedbyaddress(myzaddr),
+            self.nodes[3].z_listreceivedbyaddress(myzaddr))
+
+        # Node 3's balances should be unchanged without explicitly requesting
+        # to include watch-only balances
+        assert_equal({k: Decimal(v) for k, v in self.nodes[3].z_gettotalbalance().items()}, {
+            'transparent': node3mined,
+            'private': zsendmany2notevalue,
+            'total': node3mined + zsendmany2notevalue,
+        })
+
+        # Wallet can't cache nullifiers for notes received by addresses it only has a
+        # viewing key for, and therefore can't detect spends. So it sees a balance
+        # corresponding to the sum of all notes the address received.
+        # TODO: Fix this during the Sapling upgrade (via #2277)
+        assert_equal({k: Decimal(v) for k, v in self.nodes[3].z_gettotalbalance(1, True).items()}, {
+            'transparent': node3mined + Decimal('1.0'),
+            'private': zsendmany2notevalue + zsendmanynotevalue + zaddrremaining + zaddrremaining2,
+            'total': node3mined + Decimal('1.0') + zsendmany2notevalue + zsendmanynotevalue + zaddrremaining + zaddrremaining2,
+        })
+
+        # Check individual balances reflect the above
+        assert_equal(self.nodes[3].z_getbalance(mytaddr1), Decimal('1.0'))
+        assert_equal(self.nodes[3].z_getbalance(myzaddr), zsendmanynotevalue + zaddrremaining + zaddrremaining2)
+
 if __name__ == '__main__':
     WalletNullifiersTest().main ()

src/gtest/test_keystore.cpp

@@ -65,6 +65,11 @@ TEST(keystore_tests, StoreAndRetrieveViewingKey) {
     EXPECT_FALSE(keyStore.GetSpendingKey(addr, skOut));
     EXPECT_FALSE(keyStore.GetNoteDecryptor(addr, decOut));
 
+    // and we can't find it in our list of addresses
+    std::set<libzcash::PaymentAddress> addresses;
+    keyStore.GetPaymentAddresses(addresses);
+    EXPECT_FALSE(addresses.count(addr));
+
     keyStore.AddViewingKey(vk);
     EXPECT_TRUE(keyStore.HaveViewingKey(addr));
     EXPECT_TRUE(keyStore.GetViewingKey(addr, vkOut));
@@ -78,11 +83,19 @@ TEST(keystore_tests, StoreAndRetrieveViewingKey) {
     EXPECT_TRUE(keyStore.GetNoteDecryptor(addr, decOut));
     EXPECT_EQ(ZCNoteDecryption(sk.receiving_key()), decOut);
 
+    // ... and we should find it in our list of addresses
+    addresses.clear();
+    keyStore.GetPaymentAddresses(addresses);
+    EXPECT_TRUE(addresses.count(addr));
+
     keyStore.RemoveViewingKey(vk);
     EXPECT_FALSE(keyStore.HaveViewingKey(addr));
     EXPECT_FALSE(keyStore.GetViewingKey(addr, vkOut));
     EXPECT_FALSE(keyStore.HaveSpendingKey(addr));
     EXPECT_FALSE(keyStore.GetSpendingKey(addr, skOut));
+    addresses.clear();
+    keyStore.GetPaymentAddresses(addresses);
+    EXPECT_FALSE(addresses.count(addr));
 
     // We still have a decryptor because those are cached in memory
     // (and also we only remove viewing keys when adding a spending key)

src/keystore.h

@@ -174,6 +174,12 @@ public:
                 setAddress.insert((*mi).first);
                 mi++;
             }
+            ViewingKeyMap::const_iterator mvi = mapViewingKeys.begin();
+            while (mvi != mapViewingKeys.end())
+            {
+                setAddress.insert((*mvi).first);
+                mvi++;
+            }
         }
     }
 

src/rpcclient.cpp

@@ -103,9 +103,12 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "zcbenchmark", 1 },
     { "zcbenchmark", 2 },
     { "getblocksubsidy", 0},
+    { "z_listaddresses", 0},
     { "z_listreceivedbyaddress", 1},
     { "z_getbalance", 1},
     { "z_gettotalbalance", 0},
+    { "z_gettotalbalance", 1},
+    { "z_gettotalbalance", 2},
     { "z_sendmany", 1},
     { "z_sendmany", 2},
     { "z_sendmany", 3},

src/wallet/rpcwallet.cpp

@@ -2960,9 +2960,10 @@ UniValue z_listaddresses(const UniValue& params, bool fHelp)
 
     if (fHelp || params.size() > 1)
         throw runtime_error(
-            "z_listaddresses\n"
+            "z_listaddresses ( includeWatchonly )\n"
             "\nReturns the list of zaddr belonging to the wallet.\n"
             "\nArguments:\n"
+            "1. includeWatchonly (bool, optional, default=false) Also include watchonly addresses (see 'z_importviewingkey')\n"
             "\nResult:\n"
             "[                     (json array of string)\n"
             "  \"zaddr\"           (string) a zaddr belonging to the wallet\n"
@@ -2975,16 +2976,23 @@ UniValue z_listaddresses(const UniValue& params, bool fHelp)
 
     LOCK2(cs_main, pwalletMain->cs_wallet);
 
+    bool fIncludeWatchonly = false;
+    if (params.size() > 0) {
+        fIncludeWatchonly = params[0].get_bool();
+    }
+
     UniValue ret(UniValue::VARR);
     std::set<libzcash::PaymentAddress> addresses;
     pwalletMain->GetPaymentAddresses(addresses);
     for (auto addr : addresses ) {
-        ret.push_back(CZCPaymentAddress(addr).ToString());
+        if (fIncludeWatchonly || pwalletMain->HaveSpendingKey(addr)) {
+            ret.push_back(CZCPaymentAddress(addr).ToString());
+        }
     }
     return ret;
 }
 
-CAmount getBalanceTaddr(std::string transparentAddress, int minDepth=1) {
+CAmount getBalanceTaddr(std::string transparentAddress, int minDepth=1, bool ignoreUnspendable=true) {
     set<CBitcoinAddress> setAddress;
     vector<COutput> vecOutputs;
     CAmount balance = 0;
@@ -3006,6 +3014,10 @@ CAmount getBalanceTaddr(std::string transparentAddress, int minDepth=1) {
             continue;
         }
 
+        if (ignoreUnspendable && !out.fSpendable) {
+            continue;
+        }
+
         if (setAddress.size()) {
             CTxDestination address;
             if (!ExtractDestination(out.tx->vout[out.i].scriptPubKey, address)) {
@@ -3023,11 +3035,11 @@ CAmount getBalanceTaddr(std::string transparentAddress, int minDepth=1) {
     return balance;
 }
 
-CAmount getBalanceZaddr(std::string address, int minDepth = 1) {
+CAmount getBalanceZaddr(std::string address, int minDepth = 1, bool ignoreUnspendable=true) {
     CAmount balance = 0;
     std::vector<CNotePlaintextEntry> entries;
     LOCK2(cs_main, pwalletMain->cs_wallet);
-    pwalletMain->GetFilteredNotes(entries, address, minDepth);
+    pwalletMain->GetFilteredNotes(entries, address, minDepth, true, ignoreUnspendable);
     for (auto & entry : entries) {
         balance += CAmount(entry.plaintext.value);
     }
@@ -3076,14 +3088,14 @@ UniValue z_listreceivedbyaddress(const UniValue& params, bool fHelp)
         throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid zaddr.");
     }
 
-    if (!pwalletMain->HaveSpendingKey(zaddr)) {
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key not found.");
+    if (!(pwalletMain->HaveSpendingKey(zaddr) || pwalletMain->HaveViewingKey(zaddr))) {
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key or viewing key not found.");
     }
 
 
     UniValue result(UniValue::VARR);
     std::vector<CNotePlaintextEntry> entries;
-    pwalletMain->GetFilteredNotes(entries, fromaddress, nMinDepth, false);
+    pwalletMain->GetFilteredNotes(entries, fromaddress, nMinDepth, false, false);
     for (CNotePlaintextEntry & entry : entries) {
         UniValue obj(UniValue::VOBJ);
         obj.push_back(Pair("txid",entry.jsop.hash.ToString()));
@@ -3142,16 +3154,16 @@ UniValue z_getbalance(const UniValue& params, bool fHelp)
         } catch (const std::runtime_error&) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid from address, should be a taddr or zaddr.");
         }
-        if (!pwalletMain->HaveSpendingKey(zaddr)) {
-             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key not found.");
+        if (!(pwalletMain->HaveSpendingKey(zaddr) || pwalletMain->HaveViewingKey(zaddr))) {
+             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "From address does not belong to this node, zaddr spending key or viewing key not found.");
         }
     }
 
     CAmount nBalance = 0;
     if (fromTaddr) {
-        nBalance = getBalanceTaddr(fromaddress, nMinDepth);
+        nBalance = getBalanceTaddr(fromaddress, nMinDepth, false);
     } else {
-        nBalance = getBalanceZaddr(fromaddress, nMinDepth);
+        nBalance = getBalanceZaddr(fromaddress, nMinDepth, false);
     }
 
     return ValueFromAmount(nBalance);
@@ -3163,12 +3175,13 @@ UniValue z_gettotalbalance(const UniValue& params, bool fHelp)
     if (!EnsureWalletIsAvailable(fHelp))
         return NullUniValue;
 
-    if (fHelp || params.size() > 1)
+    if (fHelp || params.size() > 2)
         throw runtime_error(
-            "z_gettotalbalance ( minconf )\n"
+            "z_gettotalbalance ( minconf includeWatchonly )\n"
             "\nReturn the total value of funds stored in the node’s wallet.\n"
             "\nArguments:\n"
             "1. minconf          (numeric, optional, default=1) Only include private and transparent transactions confirmed at least this many times.\n"
+            "2. includeWatchonly (bool, optional, default=false) Also include balance in watchonly addresses (see 'importaddress' and 'z_importviewingkey')\n"
             "\nResult:\n"
             "{\n"
             "  \"transparent\": xxxxx,     (numeric) the total balance of transparent funds\n"
@@ -3187,19 +3200,24 @@ UniValue z_gettotalbalance(const UniValue& params, bool fHelp)
     LOCK2(cs_main, pwalletMain->cs_wallet);
 
     int nMinDepth = 1;
-    if (params.size() == 1) {
+    if (params.size() > 0) {
         nMinDepth = params[0].get_int();
     }
     if (nMinDepth < 0) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "Minimum number of confirmations cannot be less than 0");
     }
 
+    bool fIncludeWatchonly = false;
+    if (params.size() > 1) {
+        fIncludeWatchonly = params[1].get_bool();
+    }
+
     // getbalance and "getbalance * 1 true" should return the same number
     // but they don't because wtx.GetAmounts() does not handle tx where there are no outputs
     // pwalletMain->GetBalance() does not accept min depth parameter
     // so we use our own method to get balance of utxos.
-    CAmount nBalance = getBalanceTaddr("", nMinDepth);
-    CAmount nPrivateBalance = getBalanceZaddr("", nMinDepth);
+    CAmount nBalance = getBalanceTaddr("", nMinDepth, !fIncludeWatchonly);
+    CAmount nPrivateBalance = getBalanceZaddr("", nMinDepth, !fIncludeWatchonly);
     CAmount nTotalBalance = nBalance + nPrivateBalance;
     UniValue result(UniValue::VOBJ);
     result.push_back(Pair("transparent", FormatMoney(nBalance)));