Daemon RPC: high_height_ok req boolean field /getblocks.bin

Behavior before: when start_height > chain tip, response fails

Behavior after: when req.high_height_ok is true && req.start_height
> chain tip, server rerturns a successful response that includes
chain height

2 files changed, 13 insertions, 3 deletions

diff --git a/src/rpc/core_rpc_server.cpp b/src/rpc/core_rpc_server.cpp
index 16d66e79d..437829dba 100644
--- a/src/rpc/core_rpc_server.cpp
+++ b/src/rpc/core_rpc_server.cpp
@@ -702,12 +702,20 @@ namespace cryptonote
     if (get_blocks)
     {
       // quick check for noop
-      if (!req.block_ids.empty())
+      if (req.start_height > 0 || !req.block_ids.empty())
       {
         uint64_t last_block_height;
         crypto::hash last_block_hash;
         m_core.get_blockchain_top(last_block_height, last_block_hash);
-        if (last_block_hash == req.block_ids.front())
+
+        if (!req.high_height_ok && req.start_height > last_block_height)
+        {
+          res.status = "Failed";
+          return true;
+        }
+
+        if (req.start_height > last_block_height ||
+           (!req.block_ids.empty() && last_block_hash == req.block_ids.front()))
         {
           res.start_height = 0;
           res.current_height = last_block_height + 1;
diff --git a/src/rpc/core_rpc_server_commands_defs.h b/src/rpc/core_rpc_server_commands_defs.h
index c634b8957..edd7d2416 100644
--- a/src/rpc/core_rpc_server_commands_defs.h
+++ b/src/rpc/core_rpc_server_commands_defs.h
@@ -88,7 +88,7 @@ namespace cryptonote
 // advance which version they will stop working with
 // Don't go over 32767 for any of these
 #define CORE_RPC_VERSION_MAJOR 3
-#define CORE_RPC_VERSION_MINOR 14
+#define CORE_RPC_VERSION_MINOR 15
 #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)
 
@@ -176,6 +176,7 @@ namespace cryptonote
       uint64_t    start_height;
       bool        prune;
       bool        no_miner_tx;
+      bool        high_height_ok;
       uint64_t    pool_info_since;
       BEGIN_KV_SERIALIZE_MAP()
         KV_SERIALIZE_PARENT(rpc_access_request_base)
@@ -184,6 +185,7 @@ namespace cryptonote
         KV_SERIALIZE(start_height)
         KV_SERIALIZE(prune)
         KV_SERIALIZE_OPT(no_miner_tx, false)
+        KV_SERIALIZE_OPT(high_height_ok, false) // default false maintains backwards compatibility for clients that relied on failure on high height
         KV_SERIALIZE_OPT(pool_info_since, (uint64_t)0)
       END_KV_SERIALIZE_MAP()
     };