Generalize the number of epochs old a peg-in can be and still be valid

Author: instagibbs

src/chainparams.cpp

@@ -134,6 +134,7 @@ class CMainParams : public CChainParams {
         g_signed_blocks = false;
         g_con_elementsmode = false;
         g_con_blockheightinheader = false;
+        consensus.total_valid_epochs = 0;
 
         /**
          * The message start string is designed to be unlikely to occur in normal data.
@@ -263,6 +264,7 @@ class CTestNetParams : public CChainParams {
         g_signed_blocks = false;
         g_con_elementsmode = false;
         g_con_blockheightinheader = false;
+        consensus.total_valid_epochs = 0;
 
         pchMessageStart[0] = 0x0b;
         pchMessageStart[1] = 0x11;
@@ -366,6 +368,7 @@ class CRegTestParams : public CChainParams {
         g_signed_blocks = false;
         g_con_elementsmode = false;
         g_con_blockheightinheader = false;
+        consensus.total_valid_epochs = 0;
 
         pchMessageStart[0] = 0xfa;
         pchMessageStart[1] = 0xbf;
@@ -582,6 +585,8 @@ class CCustomParams : public CRegTestParams {
         uint256 entropy;
         GenerateAssetEntropy(entropy,  COutPoint(uint256(commit), 0), parentGenesisBlockHash);
 
+        consensus.total_valid_epochs = args.GetArg("-total_valid_epochs", 2);
+
         // Elements serialization uses derivation, bitcoin serialization uses 0x00
         if (g_con_elementsmode) {
             CalculateAsset(consensus.pegged_asset, entropy);

src/chainparamsbase.cpp

@@ -48,6 +48,7 @@ void SetupChainParamsBaseOptions()
     gArgs.AddArg("-con_csv_deploy_start", "Starting height for CSV deployment. (default: -1, which means ACTIVE from genesis)", false, OptionsCategory::ELEMENTS);
     gArgs.AddArg("-con_dyna_deploy_start", "Starting height for Dynamic Federations deployment. Once active, signblockscript becomes a BIP141 WSH scriptPubKey of the original signblockscript. All other dynamic parameters stay constant.(default: -1, which means ACTIVE from genesis)", false, OptionsCategory::ELEMENTS);
     gArgs.AddArg("-dynamic_epoch_length", "Per-chain parameter that sets how many blocks dynamic federation voting and enforcement are in effect for.", false, OptionsCategory::ELEMENTS);
+    gArgs.AddArg("-total_valid_epochs", "Per-chain parameter that sets how long a particular fedpegscript is in effect for.", false, OptionsCategory::ELEMENTS);
     // END ELEMENTS
     //
 }

src/consensus/params.h

@@ -105,6 +105,8 @@ struct Params {
     uint32_t dynamic_epoch_length = std::numeric_limits<uint32_t>::max();
     // Used to seed the extension space for first dynamic blocks
     std::vector<std::vector<unsigned char>> first_extension_space;
+    // Used to allow M-epoch-old peg-in addresses as deposits
+    size_t total_valid_epochs;
 };
 } // namespace Consensus
 

src/pegins.cpp

@@ -476,27 +476,23 @@ std::vector<std::pair<CScript, CScript>> GetValidFedpegScripts(const CBlockIndex
         fedpegscripts.push_back(std::make_pair(next_param.m_fedpeg_program, next_param.m_fedpegscript));
     }
 
-    // Next we walk backwards up to two epoch start blocks
-    const CBlockIndex* p_current_epoch_start = pblockindex->GetAncestor(epoch_start_height);
-    const CBlockIndex* p_prev_epoch_start = pblockindex->GetAncestor(epoch_start_height-epoch_length);
+    // Next we walk backwards up to M epoch starts
+    for (size_t i = 0; i < params.total_valid_epochs; i++) {
 
-    if (p_current_epoch_start) {
-        if (!p_current_epoch_start->dynafed_params.IsNull()) {
-            fedpegscripts.push_back(std::make_pair(p_current_epoch_start->dynafed_params.m_current.m_fedpeg_program, p_current_epoch_start->dynafed_params.m_current.m_fedpegscript));
-        } else {
-            fedpegscripts.push_back(std::make_pair(GetScriptForDestination(ScriptHash(GetScriptForDestination(WitnessV0ScriptHash(params.fedpegScript)))), params.fedpegScript));
+        const CBlockIndex* p_epoch_start = pblockindex->GetAncestor(epoch_start_height-i*epoch_length);
+
+        // We're done here, for whatever reason.
+        if (!p_epoch_start) {
+            break;
         }
-    }
 
-    if (p_prev_epoch_start) {
-        if (!p_prev_epoch_start->dynafed_params.IsNull()) {
-            fedpegscripts.push_back(std::make_pair(p_prev_epoch_start->dynafed_params.m_current.m_fedpeg_program, p_prev_epoch_start->dynafed_params.m_current.m_fedpegscript));
+        if (!p_epoch_start->dynafed_params.IsNull()) {
+            fedpegscripts.push_back(std::make_pair(p_epoch_start->dynafed_params.m_current.m_fedpeg_program, p_epoch_start->dynafed_params.m_current.m_fedpegscript));
         } else {
             fedpegscripts.push_back(std::make_pair(GetScriptForDestination(ScriptHash(GetScriptForDestination(WitnessV0ScriptHash(params.fedpegScript)))), params.fedpegScript));
         }
     }
-
     // Only return up to the latest two of three possible fedpegscripts, which are enforced
-    fedpegscripts.resize(std::min((int)fedpegscripts.size(), 2));
+    fedpegscripts.resize(std::min(fedpegscripts.size(), params.total_valid_epochs));
     return fedpegscripts;
 }

src/rpc/blockchain.cpp

@@ -1384,6 +1384,7 @@ UniValue getblockchaininfo(const JSONRPCRequest& request)
             "  \"current_signblock_hex\" : \"xxxx\", (string) Hex of sign block challenge data enforced on the next block.\n"
             "  \"max_block_witness\" : xx,     (numeric) maximum sized block witness serialized size for the next block.\n"
             "  \"epoch_length\" : xx,          (numeric) Length of dynamic federations epoch, or signaling period\n"
+            "  \"total_valid_epochs\" : xx,    (numeric) Number of epochs a given fedpscript is valid for, defined per chain.\n"
             "  \"epoch_age\" : xx,             (numeric) number of blocks into a dynamic federation epoch chain tip is. This number is between 0 to epoch_length-1\n"
             "  \"extension_space\" : [\"xxxx\", ...], (array) Array of extension fields in dynamic blockheader\n"
             "  \"pruneheight\": xxxxxx,        (numeric) lowest-height complete block stored (only present if pruning is enabled)\n"
@@ -1468,6 +1469,7 @@ UniValue getblockchaininfo(const JSONRPCRequest& request)
             }
             obj.pushKV("extension_space", arr);
             obj.pushKV("epoch_length", (uint64_t)chainparams.GetConsensus().dynamic_epoch_length);
+            obj.pushKV("total_valid_epochs", (uint64_t)chainparams.GetConsensus().total_valid_epochs);
             obj.pushKV("epoch_age", (uint64_t)(chainActive.Tip()->nHeight % chainparams.GetConsensus().dynamic_epoch_length));
         }
     }