add GetTotalBlocksEstimate() function, move magic number to constant

src/main.cpp

@@ -25,6 +25,8 @@ map<COutPoint, CInPoint> mapNextTx;
 map<uint256, CBlockIndex*> mapBlockIndex;
 uint256 hashGenesisBlock("0x000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f");
 CBigNum bnProofOfWorkLimit(~uint256(0) >> 32);
+const int nTotalBlocksEstimate = 131000; // Conservative estimate of total nr of blocks on main chain
+const int nInitialBlockThreshold = 10000; // Regard blocks up until N-threshold as "initial download"
 CBlockIndex* pindexGenesisBlock = NULL;
 int nBestHeight = -1;
 CBigNum bnBestChainWork = 0;
@@ -1156,9 +1158,22 @@ bool CheckProofOfWork(uint256 hash, unsigned int nBits)
     return true;
 }
 
+// Return conservative estimate of total number of blocks, 0 if unknown
+int GetTotalBlocksEstimate()
+{
+    if(fTestNet)
+    {
+        return 0;
+    }
+    else
+    {
+        return nTotalBlocksEstimate;
+    }
+}
+
 bool IsInitialBlockDownload()
 {
-    if (pindexBest == NULL || (!fTestNet && nBestHeight < 118000))
+    if (pindexBest == NULL || nBestHeight < (GetTotalBlocksEstimate()-nInitialBlockThreshold))
         return true;
     static int64 nLastUpdate;
     static CBlockIndex* pindexLastBest;

src/main.h

@@ -118,6 +118,7 @@ void FormatHashBuffers(CBlock* pblock, char* pmidstate, char* pdata, char* phash
 bool CheckWork(CBlock* pblock, CReserveKey& reservekey);
 void BitcoinMiner();
 bool CheckProofOfWork(uint256 hash, unsigned int nBits);
+int GetTotalBlocksEstimate();
 bool IsInitialBlockDownload();
 std::string GetWarnings(std::string strFor);