From d6440ab319ea6adf21485550d6a08ae452d49818 Mon Sep 17 00:00:00 2001
From: moneromooo-monero <moneromooo-monero@users.noreply.github.com>
Date: Sat, 28 Apr 2018 12:11:42 +0100
Subject: wallet2: recover from index out of hashchain bounds error

This can happen when there's a very large reorg on the daemon
(ie, on testnet)
---
 src/wallet/wallet2.cpp | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

(limited to 'src/wallet/wallet2.cpp')

diff --git a/src/wallet/wallet2.cpp b/src/wallet/wallet2.cpp
index 40a43b8e7..66188b823 100644
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@@ -1823,7 +1823,7 @@ void wallet2::process_parsed_blocks(uint64_t start_height, const std::vector<cry
   blocks_added = 0;
 
   THROW_WALLET_EXCEPTION_IF(blocks.size() != parsed_blocks.size(), error::wallet_internal_error, "size mismatch");
-  THROW_WALLET_EXCEPTION_IF(!m_blockchain.is_in_bounds(current_index), error::wallet_internal_error, "Index out of bounds of hashchain");
+  THROW_WALLET_EXCEPTION_IF(!m_blockchain.is_in_bounds(current_index), error::out_of_hashchain_bounds_error);
 
   tools::threadpool& tpool = tools::threadpool::getInstance();
   tools::threadpool::waiter waiter;
@@ -2269,12 +2269,12 @@ void wallet2::update_pool_state(bool refreshed)
   MDEBUG("update_pool_state end");
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::fast_refresh(uint64_t stop_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history)
+void wallet2::fast_refresh(uint64_t stop_height, uint64_t &blocks_start_height, std::list<crypto::hash> &short_chain_history, bool force)
 {
   std::vector<crypto::hash> hashes;
 
   const uint64_t checkpoint_height = m_checkpoints.get_max_height();
-  if (stop_height > checkpoint_height && m_blockchain.size()-1 < checkpoint_height)
+  if ((stop_height > checkpoint_height && m_blockchain.size()-1 < checkpoint_height) && !force)
   {
     // we will drop all these, so don't bother getting them
     uint64_t missing_blocks = m_checkpoints.get_max_height() - m_blockchain.size();
@@ -2439,6 +2439,7 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
       std::vector<cryptonote::block_complete_entry> next_blocks;
       std::vector<parsed_block> next_parsed_blocks;
       bool error = false;
+      added_blocks = 0;
       if (!first && blocks.empty())
       {
         refreshed = false;
@@ -2448,7 +2449,33 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
 
       if (!first)
       {
-        process_parsed_blocks(blocks_start_height, blocks, parsed_blocks, added_blocks);
+        try
+        {
+          process_parsed_blocks(blocks_start_height, blocks, parsed_blocks, added_blocks);
+        }
+        catch (const tools::error::out_of_hashchain_bounds_error&)
+        {
+          MINFO("Daemon claims next refresh block is out of hash chain bounds, resetting hash chain");
+          uint64_t stop_height = m_blockchain.offset();
+          std::vector<crypto::hash> tip(m_blockchain.size() - m_blockchain.offset());
+          for (size_t i = m_blockchain.offset(); i < m_blockchain.size(); ++i)
+            tip[i - m_blockchain.offset()] = m_blockchain[i];
+          cryptonote::block b;
+          generate_genesis(b);
+          m_blockchain.clear();
+          m_blockchain.push_back(get_block_hash(b));
+          short_chain_history.clear();
+          get_short_chain_history(short_chain_history);
+          fast_refresh(stop_height, blocks_start_height, short_chain_history, true);
+          THROW_WALLET_EXCEPTION_IF(m_blockchain.size() != stop_height, error::wallet_internal_error, "Unexpected hashchain size");
+          THROW_WALLET_EXCEPTION_IF(m_blockchain.offset() != 0, error::wallet_internal_error, "Unexpected hashchain offset");
+          for (const auto &h: tip)
+            m_blockchain.push_back(h);
+          short_chain_history.clear();
+          get_short_chain_history(short_chain_history);
+          start_height = stop_height;
+          throw std::runtime_error(""); // loop again
+        }
         blocks_fetched += added_blocks;
       }
       waiter.wait(&tpool);
@@ -2478,6 +2505,7 @@ void wallet2::refresh(bool trusted_daemon, uint64_t start_height, uint64_t & blo
       if(try_count < 3)
       {
         LOG_PRINT_L1("Another try pull_blocks (try_count=" << try_count << ")...");
+        first = true;
         ++try_count;
       }
       else
-- 
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