wallet: initialize URI parse outputs

Successful parses left optional outputs unchanged when the URI omitted them, which could expose stale values or an uninitialized amount

Initialize them after validating the address so outputs only describe the current URI

src/wallet/wallet2.cpp

@@ -14869,6 +14869,14 @@ bool wallet2::parse_uri(const std::string &uri, std::string &address, std::strin
     error = std::string("URI has wrong address: ") + address;
     return false;
   }
+
+  payment_id.clear();
+  amount = 0;
+  tx_description.clear();
+  recipient_name.clear();
+  unknown_parameters.clear();
+  error.clear();
+
   if (!strchr(remainder.c_str(), '?'))
     return true;
 
@@ -14896,7 +14904,6 @@ bool wallet2::parse_uri(const std::string &uri, std::string &address, std::strin
 
     if (kv[0] == "tx_amount")
     {
-      amount = 0;
       if (!cryptonote::parse_amount(amount, kv[1]))
       {
         error = std::string("URI has invalid amount: ") + kv[1];

tests/unit_tests/uri.cpp

@@ -82,6 +82,27 @@ TEST(uri, good_address)
   ASSERT_EQ(address, TEST_ADDRESS);
 }
 
+TEST(uri, resets_outputs)
+{
+  std::string address = "old address";
+  std::string payment_id = "old payment id";
+  std::string recipient_name = "old recipient name";
+  std::string description = "old description";
+  std::string error = "old error";
+  uint64_t amount = 1;
+  std::vector<std::string> unknown_parameters{"old=parameter"};
+  tools::wallet2 w(cryptonote::TESTNET);
+
+  ASSERT_TRUE(w.parse_uri("monero:" TEST_ADDRESS, address, payment_id, amount, description, recipient_name, unknown_parameters, error));
+  EXPECT_EQ(address, TEST_ADDRESS);
+  EXPECT_EQ(amount, 0);
+  EXPECT_TRUE(payment_id.empty());
+  EXPECT_TRUE(description.empty());
+  EXPECT_TRUE(recipient_name.empty());
+  EXPECT_TRUE(unknown_parameters.empty());
+  EXPECT_TRUE(error.empty());
+}
+
 TEST(uri, good_integrated_address)
 {
   PARSE_URI("monero:" TEST_INTEGRATED_ADDRESS, true);