alt_chain_info can now give more info about a particular alt chain

src/cryptonote_core/blockchain.cpp

@@ -4393,9 +4393,9 @@ std::map<uint64_t, std::tuple<uint64_t, uint64_t, uint64_t>> Blockchain:: get_ou
   return m_db->get_output_histogram(amounts, unlocked, recent_cutoff, min_count);
 }
 
-std::list<std::pair<Blockchain::block_extended_info,uint64_t>> Blockchain::get_alternative_chains() const
+std::list<std::pair<Blockchain::block_extended_info,std::vector<crypto::hash>>> Blockchain::get_alternative_chains() const
 {
-  std::list<std::pair<Blockchain::block_extended_info,uint64_t>> chains;
+  std::list<std::pair<Blockchain::block_extended_info,std::vector<crypto::hash>>> chains;
 
   for (const auto &i: m_alternative_chains)
   {
@@ -4411,15 +4411,16 @@ std::list<std::pair<Blockchain::block_extended_info,uint64_t>> Blockchain::get_a
     }
     if (!found)
     {
-      uint64_t length = 1;
+      std::vector<crypto::hash> chain;
       auto h = i.second.bl.prev_id;
+      chain.push_back(top);
       blocks_ext_by_hash::const_iterator prev;
       while ((prev = m_alternative_chains.find(h)) != m_alternative_chains.end())
       {
+        chain.push_back(h);
         h = prev->second.bl.prev_id;
-        ++length;
       }
-      chains.push_back(std::make_pair(i.second, length));
+      chains.push_back(std::make_pair(i.second, chain));
     }
   }
   return chains;

src/cryptonote_core/blockchain.h

@@ -939,7 +939,7 @@ namespace cryptonote
      *
      * @return a list of chains
      */
-    std::list<std::pair<block_extended_info,uint64_t>> get_alternative_chains() const;
+    std::list<std::pair<block_extended_info,std::vector<crypto::hash>>> get_alternative_chains() const;
 
     void add_txpool_tx(transaction &tx, const txpool_tx_meta_t &meta);
     void update_txpool_tx(const crypto::hash &txid, const txpool_tx_meta_t &meta);

src/daemon/command_parser_executor.cpp

@@ -599,13 +599,13 @@ bool t_command_parser_executor::print_coinbase_tx_sum(const std::vector<std::str
 
 bool t_command_parser_executor::alt_chain_info(const std::vector<std::string>& args)
 {
-  if(args.size())
+  if(args.size() > 1)
   {
-    std::cout << "No parameters allowed" << std::endl;
+    std::cout << "usage: alt_chain_info [block_hash]" << std::endl;
     return false;
   }
 
-  return m_executor.alt_chain_info();
+  return m_executor.alt_chain_info(args.size() == 1 ? args[0] : "");
 }
 
 bool t_command_parser_executor::print_blockchain_dynamic_stats(const std::vector<std::string>& args)

src/daemon/command_server.cpp

@@ -255,6 +255,7 @@ t_command_server::t_command_server(
     m_command_lookup.set_handler(
       "alt_chain_info"
     , std::bind(&t_command_parser_executor::alt_chain_info, &m_parser, p::_1)
+    , "alt_chain_info [blockhash]"
     , "Print the information about alternative chains."
     );
     m_command_lookup.set_handler(

src/daemon/rpc_command_executor.cpp

@@ -1628,7 +1628,7 @@ bool t_rpc_command_executor::print_coinbase_tx_sum(uint64_t height, uint64_t cou
   return true;
 }
 
-bool t_rpc_command_executor::alt_chain_info()
+bool t_rpc_command_executor::alt_chain_info(const std::string &tip)
 {
   cryptonote::COMMAND_RPC_GET_INFO::request ireq;
   cryptonote::COMMAND_RPC_GET_INFO::response ires;
@@ -1663,12 +1663,32 @@ bool t_rpc_command_executor::alt_chain_info()
     }
   }
 
-  tools::msg_writer() << boost::lexical_cast<std::string>(res.chains.size()) << " alternate chains found:";
-  for (const auto &chain: res.chains)
+  if (tip.empty())
   {
-    uint64_t start_height = (chain.height - chain.length + 1);
-    tools::msg_writer() << chain.length << " blocks long, from height " << start_height << " (" << (ires.height - start_height - 1)
-        << " deep), diff " << chain.difficulty << ": " << chain.block_hash;
+    tools::msg_writer() << boost::lexical_cast<std::string>(res.chains.size()) << " alternate chains found:";
+    for (const auto &chain: res.chains)
+    {
+      uint64_t start_height = (chain.height - chain.length + 1);
+      tools::msg_writer() << chain.length << " blocks long, from height " << start_height << " (" << (ires.height - start_height - 1)
+          << " deep), diff " << chain.difficulty << ": " << chain.block_hash;
+    }
+  }
+  else
+  {
+    const auto i = std::find_if(res.chains.begin(), res.chains.end(), [&tip](cryptonote::COMMAND_RPC_GET_ALTERNATE_CHAINS::chain_info &info){ return info.block_hash == tip; });
+    if (i != res.chains.end())
+    {
+      const auto &chain = *i;
+      tools::success_msg_writer() << "Found alternate chain with tip " << tip;
+      uint64_t start_height = (chain.height - chain.length + 1);
+      tools::msg_writer() << chain.length << " blocks long, from height " << start_height << " (" << (ires.height - start_height - 1)
+          << " deep), diff " << chain.difficulty << ":";
+      for (const std::string &block_id: chain.block_hashes)
+        tools::msg_writer() << "  " << block_id;
+      tools::msg_writer() << "Chain parent on main chain: " << chain.main_chain_parent_block;
+    }
+    else
+      tools::fail_msg_writer() << "Block hash " << tip << " is not the tip of any known alternate chain";
   }
   return true;
 }

src/daemon/rpc_command_executor.h

@@ -143,7 +143,7 @@ public:
 
   bool print_coinbase_tx_sum(uint64_t height, uint64_t count);
 
-  bool alt_chain_info();
+  bool alt_chain_info(const std::string &tip);
 
   bool print_blockchain_dynamic_stats(uint64_t nblocks);
 

src/rpc/core_rpc_server.cpp

@@ -1774,10 +1774,22 @@ namespace cryptonote
     PERF_TIMER(on_get_alternate_chains);
     try
     {
-      std::list<std::pair<Blockchain::block_extended_info, uint64_t>> chains = m_core.get_blockchain_storage().get_alternative_chains();
+      std::list<std::pair<Blockchain::block_extended_info, std::vector<crypto::hash>>> chains = m_core.get_blockchain_storage().get_alternative_chains();
       for (const auto &i: chains)
       {
-        res.chains.push_back(COMMAND_RPC_GET_ALTERNATE_CHAINS::chain_info{epee::string_tools::pod_to_hex(get_block_hash(i.first.bl)), i.first.height, i.second, i.first.cumulative_difficulty});
+        res.chains.push_back(COMMAND_RPC_GET_ALTERNATE_CHAINS::chain_info{epee::string_tools::pod_to_hex(get_block_hash(i.first.bl)), i.first.height, i.second.size(), i.first.cumulative_difficulty, {}, std::string()});
+        res.chains.back().block_hashes.reserve(i.second.size());
+        for (const crypto::hash &block_id: i.second)
+          res.chains.back().block_hashes.push_back(epee::string_tools::pod_to_hex(block_id));
+        if (i.first.height < i.second.size())
+        {
+          res.status = "Error finding alternate chain attachment point";
+          return true;
+        }
+        cryptonote::block main_chain_parent_block;
+        try { main_chain_parent_block = m_core.get_blockchain_storage().get_db().get_block_from_height(i.first.height - i.second.size()); }
+        catch (const std::exception &e) { res.status = "Error finding alternate chain attachment point"; return true; }
+        res.chains.back().main_chain_parent_block = epee::string_tools::pod_to_hex(get_block_hash(main_chain_parent_block));
       }
       res.status = CORE_RPC_STATUS_OK;
     }

src/rpc/core_rpc_server_commands_defs.h

@@ -49,7 +49,7 @@ namespace cryptonote
 // advance which version they will stop working with
 // Don't go over 32767 for any of these
 #define CORE_RPC_VERSION_MAJOR 1
-#define CORE_RPC_VERSION_MINOR 20
+#define CORE_RPC_VERSION_MINOR 21
 #define MAKE_CORE_RPC_VERSION(major,minor) (((major)<<16)|(minor))
 #define CORE_RPC_VERSION MAKE_CORE_RPC_VERSION(CORE_RPC_VERSION_MAJOR, CORE_RPC_VERSION_MINOR)
 
@@ -2086,12 +2086,16 @@ namespace cryptonote
       uint64_t height;
       uint64_t length;
       uint64_t difficulty;
+      std::vector<std::string> block_hashes;
+      std::string main_chain_parent_block;
 
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE(block_hash)
         KV_SERIALIZE(height)
         KV_SERIALIZE(length)
         KV_SERIALIZE(difficulty)
+        KV_SERIALIZE(block_hashes)
+        KV_SERIALIZE(main_chain_parent_block)
       END_KV_SERIALIZE_MAP()
     };