1 files changed, 130 insertions, 0 deletions
diff --git a/src/primitives/block.cpp b/src/primitives/block.cpp
new file mode 100644
index 0000000000..3b4a360395
--- /dev/null
+++ b/src/primitives/block.cpp
@@ -0,0 +1,130 @@
+// Copyright (c) 2009-2010 Satoshi Nakamoto
+// Copyright (c) 2009-2014 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include "primitives/block.h"
+
+#include "hash.h"
+#include "tinyformat.h"
+#include "utilstrencodings.h"
+
+uint256 CBlockHeader::GetHash() const
+{
+    return Hash(BEGIN(nVersion), END(nNonce));
+}
+
+uint256 CBlock::BuildMerkleTree(bool* fMutated) const
+{
+    /* WARNING! If you're reading this because you're learning about crypto
+       and/or designing a new system that will use merkle trees, keep in mind
+       that the following merkle tree algorithm has a serious flaw related to
+       duplicate txids, resulting in a vulnerability (CVE-2012-2459).
+
+       The reason is that if the number of hashes in the list at a given time
+       is odd, the last one is duplicated before computing the next level (which
+       is unusual in Merkle trees). This results in certain sequences of
+       transactions leading to the same merkle root. For example, these two
+       trees:
+
+                    A               A
+                  /  \            /   \
+                B     C         B       C
+               / \    |        / \     / \
+              D   E   F       D   E   F   F
+             / \ / \ / \     / \ / \ / \ / \
+             1 2 3 4 5 6     1 2 3 4 5 6 5 6
+
+       for transaction lists [1,2,3,4,5,6] and [1,2,3,4,5,6,5,6] (where 5 and
+       6 are repeated) result in the same root hash A (because the hash of both
+       of (F) and (F,F) is C).
+
+       The vulnerability results from being able to send a block with such a
+       transaction list, with the same merkle root, and the same block hash as
+       the original without duplication, resulting in failed validation. If the
+       receiving node proceeds to mark that block as permanently invalid
+       however, it will fail to accept further unmodified (and thus potentially
+       valid) versions of the same block. We defend against this by detecting
+       the case where we would hash two identical hashes at the end of the list
+       together, and treating that identically to the block having an invalid
+       merkle root. Assuming no double-SHA256 collisions, this will detect all
+       known ways of changing the transactions without affecting the merkle
+       root.
+    */
+    vMerkleTree.clear();
+    vMerkleTree.reserve(vtx.size() * 2 + 16); // Safe upper bound for the number of total nodes.
+    for (std::vector<CTransaction>::const_iterator it(vtx.begin()); it != vtx.end(); ++it)
+        vMerkleTree.push_back(it->GetHash());
+    int j = 0;
+    bool mutated = false;
+    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+    {
+        for (int i = 0; i < nSize; i += 2)
+        {
+            int i2 = std::min(i+1, nSize-1);
+            if (i2 == i + 1 && i2 + 1 == nSize && vMerkleTree[j+i] == vMerkleTree[j+i2]) {
+                // Two identical hashes at the end of the list at a particular level.
+                mutated = true;
+            }
+            vMerkleTree.push_back(Hash(BEGIN(vMerkleTree[j+i]),  END(vMerkleTree[j+i]),
+                                       BEGIN(vMerkleTree[j+i2]), END(vMerkleTree[j+i2])));
+        }
+        j += nSize;
+    }
+    if (fMutated) {
+        *fMutated = mutated;
+    }
+    return (vMerkleTree.empty() ? uint256() : vMerkleTree.back());
+}
+
+std::vector<uint256> CBlock::GetMerkleBranch(int nIndex) const
+{
+    if (vMerkleTree.empty())
+        BuildMerkleTree();
+    std::vector<uint256> vMerkleBranch;
+    int j = 0;
+    for (int nSize = vtx.size(); nSize > 1; nSize = (nSize + 1) / 2)
+    {
+        int i = std::min(nIndex^1, nSize-1);
+        vMerkleBranch.push_back(vMerkleTree[j+i]);
+        nIndex >>= 1;
+        j += nSize;
+    }
+    return vMerkleBranch;
+}
+
+uint256 CBlock::CheckMerkleBranch(uint256 hash, const std::vector<uint256>& vMerkleBranch, int nIndex)
+{
+    if (nIndex == -1)
+        return uint256();
+    for (std::vector<uint256>::const_iterator it(vMerkleBranch.begin()); it != vMerkleBranch.end(); ++it)
+    {
+        if (nIndex & 1)
+            hash = Hash(BEGIN(*it), END(*it), BEGIN(hash), END(hash));
+        else
+            hash = Hash(BEGIN(hash), END(hash), BEGIN(*it), END(*it));
+        nIndex >>= 1;
+    }
+    return hash;
+}
+
+std::string CBlock::ToString() const
+{
+    std::stringstream s;
+    s << strprintf("CBlock(hash=%s, ver=%d, hashPrevBlock=%s, hashMerkleRoot=%s, nTime=%u, nBits=%08x, nNonce=%u, vtx=%u)\n",
+        GetHash().ToString(),
+        nVersion,
+        hashPrevBlock.ToString(),
+        hashMerkleRoot.ToString(),
+        nTime, nBits, nNonce,
+        vtx.size());
+    for (unsigned int i = 0; i < vtx.size(); i++)
+    {
+        s << "  " << vtx[i].ToString() << "\n";
+    }
+    s << "  vMerkleTree: ";
+    for (unsigned int i = 0; i < vMerkleTree.size(); i++)
+        s << " " << vMerkleTree[i].ToString();
+    s << "\n";
+    return s.str();
+}