Bugfix: Allow mining on top of old tip blocks for testnet (fixes testnet-in-a-box use case)

src/chainparams.cpp

@@ -51,6 +51,7 @@ public:
         vAlertPubKey = ParseHex("04fc9702847840aaf195de8442ebecedf5b095cdbb9bc716bda9110971b28a49e0ead8564ff0db22209e0374782c093bb899692d524e9d6a6956e7c5ecbcd68284");
         nDefaultPort = 8333;
         nMinerThreads = 0;
+        nMaxTipAge = 24 * 60 * 60;
         nPruneAfterHeight = 100000;
 
         /**
@@ -147,6 +148,7 @@ public:
         vAlertPubKey = ParseHex("04302390343f91cc401d56d68b123028bf52e5fca1939df127f63c6467cdf9c8e2c14b61104cf817d0b780da337893ecc4aaff1309e536162dabbdb45200ca2b0a");
         nDefaultPort = 18333;
         nMinerThreads = 0;
+        nMaxTipAge = 0x7fffffff;
         nPruneAfterHeight = 1000;
 
         //! Modify the testnet genesis block so the timestamp is valid for a later start.
@@ -206,6 +208,7 @@ public:
         pchMessageStart[2] = 0xb5;
         pchMessageStart[3] = 0xda;
         nMinerThreads = 1;
+        nMaxTipAge = 24 * 60 * 60;
         genesis.nTime = 1296688602;
         genesis.nBits = 0x207fffff;
         genesis.nNonce = 2;

src/chainparams.h

@@ -60,6 +60,7 @@ public:
     bool DefaultConsistencyChecks() const { return fDefaultConsistencyChecks; }
     /** Policy: Filter transactions that do not match well-defined patterns */
     bool RequireStandard() const { return fRequireStandard; }
+    int64_t MaxTipAge() const { return nMaxTipAge; }
     int64_t PruneAfterHeight() const { return nPruneAfterHeight; }
     /** Make miner stop after a block is found. In RPC, don't return until nGenProcLimit blocks are generated */
     bool MineBlocksOnDemand() const { return fMineBlocksOnDemand; }
@@ -80,6 +81,7 @@ protected:
     std::vector<unsigned char> vAlertPubKey;
     int nDefaultPort;
     int nMinerThreads;
+    long nMaxTipAge;
     uint64_t nPruneAfterHeight;
     std::vector<CDNSSeedData> vSeeds;
     std::vector<unsigned char> base58Prefixes[MAX_BASE58_TYPES];

src/main.cpp

@@ -1239,7 +1239,7 @@ bool IsInitialBlockDownload()
     if (lockIBDState)
         return false;
     bool state = (chainActive.Height() < pindexBestHeader->nHeight - 24 * 6 ||
-            pindexBestHeader->GetBlockTime() < GetTime() - 24 * 60 * 60);
+            pindexBestHeader->GetBlockTime() < GetTime() - chainParams.MaxTipAge());
     if (!state)
         lockIBDState = true;
     return state;