Include segwit equivalent max size in RPC getblock

segwit_equiv_hack.diff

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index a1cb89c..63fe757 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -102,6 +102,26 @@ UniValue blockToJSON(const CBlock& block, const CBlockIndex* blockindex, bool tx
     result.push_back(Pair("strippedsize", (int)::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS)));
     result.push_back(Pair("size", (int)::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION)));
     result.push_back(Pair("weight", (int)::GetBlockWeight(block)));
+
+    {
+        size_t nBlockSuperStrippedSize = 0;
+        size_t nBlockWitnessAndSigSize = 0;
+        for (auto & tx : block.vtx) {
+            CMutableTransaction mtx(tx);
+            for (auto & inp : mtx.vin) {
+                nBlockWitnessAndSigSize += 1 + inp.scriptSig.size();
+                inp.scriptSig.clear();
+            }
+            // Doesn't work with actual witness blocks
+            nBlockSuperStrippedSize += ::GetSerializeSize(mtx, SER_NETWORK, PROTOCOL_VERSION);
+        }
+        const size_t nBlockMaxTxWeight = 4000000 - (4 * (80 + ::GetSerializeSize(VARINT(block.vtx.size()), SER_NETWORK, PROTOCOL_VERSION)));
+        const size_t nBlockSimTxWeight = ((nBlockSuperStrippedSize * 4) + nBlockWitnessAndSigSize);
+        const size_t nBlockTxSize = nBlockSuperStrippedSize + nBlockWitnessAndSigSize;
+        const int64_t nSegwitEquiv = nBlockMaxTxWeight * nBlockTxSize / nBlockSimTxWeight;
+        result.push_back(Pair("segwit_equiv_hack", nSegwitEquiv));
+    }
+
     result.push_back(Pair("height", blockindex->nHeight));
     result.push_back(Pair("version", block.nVersion));
     result.push_back(Pair("versionHex", strprintf("%08x", block.nVersion)));