From 553cdeea0063a323abddeae0a3bdfe2f70775b26 Mon Sep 17 00:00:00 2001
From: Gregory Sanders <gsanders87@gmail.com>
Date: Mon, 12 Dec 2016 15:44:47 -0500
Subject: [PATCH] Greatly simplify coinbase balance checking

---
 src/validation.cpp | 25 ++++++++++++++++---------
 src/validation.h   |  5 +++++
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/validation.cpp b/src/validation.cpp
index 765bd9059d..c7b157acda 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -654,6 +654,7 @@ bool CSurjectionCheck::operator()()
 
 bool VerifyAmounts(const CCoinsViewCache& cache, const CTransaction& tx, const CAmount& excess, const uint256& excessID, std::vector<CCheck*>* pvChecks, const bool cacheStore)
 {
+    assert(!tx.IsCoinBase());
 
     std::vector<secp256k1_pedersen_commitment> vData;
     std::vector<secp256k1_pedersen_commitment *> vpCommitsIn, vpCommitsOut;
@@ -790,14 +791,6 @@ bool VerifyAmounts(const CCoinsViewCache& cache, const CTransaction& tx, const C
         }
     }
 
-    // Blinded assets and surjection proofs not supported for coinbase
-    if (tx.IsCoinBase()) {
-        for (size_t i = 0; i < tx.vout.size(); i++) {
-            if (!tx.vout[i].nAsset.IsAssetID() || !tx.vout[i].nAsset.vchSurjectionproof.empty())
-                return false;
-        }
-        return true;
-    }
 
     //Surjection proof checking of ephemeral asset keys
     std::vector<secp256k1_generator> ephemeral_input_tags;
@@ -845,6 +838,20 @@ bool VerifyAmounts(const CCoinsViewCache& cache, const CTransaction& tx, const C
     return true;
 }
 
+bool VerifyCoinbaseAmount(const CTransaction& tx, const CAmount& fees, const uint256& feeID)
+{
+    assert(tx.IsCoinBase());
+    CAmount remaining = fees;
+    for (unsigned int i = 0; i < tx.vout.size(); i++) {
+        if (!tx.vout[i].nValue.IsAmount() || !tx.vout[i].nAsset.IsAssetID())
+            return false;
+        if (feeID != BITCOINID)
+            return false;
+        remaining -= tx.vout[i].nValue.GetAmount();
+    }
+    return MoneyRange(remaining);
+}
+
 void LimitMempoolSize(CTxMemPool& pool, size_t limit, unsigned long age) {
     int expired = pool.Expire(GetTime() - age);
     if (expired != 0)
@@ -2572,7 +2579,7 @@ bool ConnectBlock(const CBlock& block, CValidationState& state, CBlockIndex* pin
     CAmount blockReward = nFees;
     if (!MoneyRange(blockReward))
         return state.DoS(100, error("ConnectBlock(): total block reward overflowed"), REJECT_INVALID, "bad-blockreward-outofrange");
-    if (!VerifyAmounts(view, *(block.vtx[0]), -blockReward, BITCOINID))
+    if (!VerifyCoinbaseAmount(*(block.vtx[0]), -blockReward, BITCOINID))
         return state.DoS(100,
                          error("ConnectBlock(): coinbase pays too much (limit=%d)",
                                blockReward),
diff --git a/src/validation.h b/src/validation.h
index 036c3c1e8f..736e7b3b86 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -408,6 +408,11 @@ bool CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoins
 */
 bool VerifyAmounts(const CCoinsViewCache& cache, const CTransaction& tx, const CAmount& excess, const uint256& excessID, std::vector<CCheck*>* pvChecks = NULL, const bool cacheStore = false);
 
+/**
+ * Verify the amounts of coinbase transactions. It will fail for any blinded amount or type.
+ * Each output must be IsAmount && IsAssetID.
+*/
+bool VerifyCoinbaseAmount(const CTransaction& tx, const CAmount& fees, const uint256& feeID);
 
 /**
  * Check if transaction is final and can be included in a block with the