wallet: ensure subaddress keys table is at least size of requested lookahead

src/wallet/wallet2.cpp

@@ -1964,6 +1964,25 @@ void wallet2::set_subaddress_lookahead(size_t major, size_t minor)
   THROW_WALLET_EXCEPTION_IF(major > 0xffffffff, error::wallet_internal_error, "Subaddress major lookahead is too large");
   THROW_WALLET_EXCEPTION_IF(minor == 0, error::wallet_internal_error, "Subaddress minor lookahead may not be zero");
   THROW_WALLET_EXCEPTION_IF(minor > 0xffffffff, error::wallet_internal_error, "Subaddress minor lookahead is too large");
+
+  if (major > m_subaddress_lookahead_major) { // if increasing the lookahead
+    // then generate new subaddress pubkeys and add them to m_subaddresses table
+    for (uint32_t i = m_subaddress_labels.size()+m_subaddress_lookahead_major; i < m_subaddress_labels.size()+major; i++) { // m_subaddress_labels are the accounts the user is conciously keeping track of. We want that number plus the lookahead major accounts in our key table
+      for (uint32_t j = 0; j < minor; j++) { // these are newly made accounts, minor index will start from zero
+        cryptonote::subaddress_index idx = {i,j};
+        create_one_off_subaddress(idx); // then generate the key and add it to the table
+      }
+    }
+  }
+  if (minor > m_subaddress_lookahead_minor) { // if increasing the minor lookahead we need to also go back and expand the existing accounts
+    for (uint32_t i = 0; i < m_subaddress_labels.size()+m_subaddress_lookahead_major; i++) {
+      uint32_t minor_idx_start = i < m_subaddress_labels.size() ? m_subaddress_labels[i].size()+m_subaddress_lookahead_minor : m_subaddress_lookahead_minor; // if there are existing minor indices being tracked under this account we need to account for that
+      for (uint32_t j = minor_idx_start; j < minor; j++) {
+        cryptonote::subaddress_index idx = {i,j};
+        create_one_off_subaddress(idx);
+      }
+    }
+  }
   m_subaddress_lookahead_major = major;
   m_subaddress_lookahead_minor = minor;
 }

tests/unit_tests/subaddress.cpp

@@ -28,6 +28,7 @@
 // 
 // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
 #include <boost/filesystem.hpp>
+#include <boost/optional/optional_io.hpp>
 #include "gtest/gtest.h"
 
 #include "include_base_utils.h"
@@ -101,3 +102,29 @@ TEST_F(WalletSubaddress, OutOfBoundsIndexes)
     EXPECT_STREQ("index.minor is out of bound", e.what());  
   }   
 }
+
+TEST_F(WalletSubaddress, ExpandPubkeyTable)
+{
+  // these test assume we are starting with the default setup state
+  EXPECT_EQ(2, w1.get_num_subaddress_accounts());
+  EXPECT_EQ(50, w1.get_subaddress_lookahead().first);
+  EXPECT_EQ(200, w1.get_subaddress_lookahead().second);
+  // get_subaddress_index looks up keys in the private m_subaddresses dictionary so we will use it to test if a key is properly being scanned for
+  cryptonote::subaddress_index test_idx = {50, 199};
+  auto subaddr = w1.get_subaddress(test_idx);
+  EXPECT_NE(boost::none, w1.get_subaddress_index(subaddr));
+  // fist test expanding the major lookahead
+  w1.set_subaddress_lookahead(100, 200);
+  EXPECT_EQ(100, w1.get_subaddress_lookahead().first);
+  EXPECT_EQ(200, w1.get_subaddress_lookahead().second);
+  test_idx = {100, 199};
+  subaddr = w1.get_subaddress(test_idx);
+  EXPECT_NE(boost::none, w1.get_subaddress_index(subaddr));
+  // next test expanding the minor lookahead
+  w1.set_subaddress_lookahead(100, 300);
+  EXPECT_EQ(100, w1.get_subaddress_lookahead().first);
+  EXPECT_EQ(300, w1.get_subaddress_lookahead().second);
+  test_idx = {100, 299};
+  subaddr = w1.get_subaddress(test_idx);
+  EXPECT_NE(boost::none, w1.get_subaddress_index(subaddr));
+}