Merge pull request #517 from gavinandresen/DoSprevention

Denial-of-service prevention

1 files changed, 46 insertions, 29 deletions

diff --git a/src/main.cpp b/src/main.cpp
index e732ddcf5d..434c8e848d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -297,24 +297,24 @@ bool CTransaction::CheckTransaction() const
 {
     // Basic checks that don't depend on any context
     if (vin.empty())
-        return error("CTransaction::CheckTransaction() : vin empty");
+        return DoS(10, error("CTransaction::CheckTransaction() : vin empty"));
     if (vout.empty())
-        return error("CTransaction::CheckTransaction() : vout empty");
+        return DoS(10, error("CTransaction::CheckTransaction() : vout empty"));
     // Size limits
     if (::GetSerializeSize(*this, SER_NETWORK) > MAX_BLOCK_SIZE)
-        return error("CTransaction::CheckTransaction() : size limits failed");
+        return DoS(100, error("CTransaction::CheckTransaction() : size limits failed"));
 
     // Check for negative or overflow output values
     int64 nValueOut = 0;
     BOOST_FOREACH(const CTxOut& txout, vout)
     {
         if (txout.nValue < 0)
-            return error("CTransaction::CheckTransaction() : txout.nValue negative");
+            return DoS(100, error("CTransaction::CheckTransaction() : txout.nValue negative"));
         if (txout.nValue > MAX_MONEY)
-            return error("CTransaction::CheckTransaction() : txout.nValue too high");
+            return DoS(100, error("CTransaction::CheckTransaction() : txout.nValue too high"));
         nValueOut += txout.nValue;
         if (!MoneyRange(nValueOut))
-            return error("CTransaction::CheckTransaction() : txout total out of range");
+            return DoS(100, error("CTransaction::CheckTransaction() : txout total out of range"));
     }
 
     // Check for duplicate inputs
@@ -329,13 +329,13 @@ bool CTransaction::CheckTransaction() const
     if (IsCoinBase())
     {
         if (vin[0].scriptSig.size() < 2 || vin[0].scriptSig.size() > 100)
-            return error("CTransaction::CheckTransaction() : coinbase script size");
+            return DoS(100, error("CTransaction::CheckTransaction() : coinbase script size"));
     }
     else
     {
         BOOST_FOREACH(const CTxIn& txin, vin)
             if (txin.prevout.IsNull())
-                return error("CTransaction::CheckTransaction() : prevout is null");
+                return DoS(10, error("CTransaction::CheckTransaction() : prevout is null"));
     }
 
     return true;
@@ -351,7 +351,7 @@ bool CTransaction::AcceptToMemoryPool(CTxDB& txdb, bool fCheckInputs, bool* pfMi
 
     // Coinbase is only valid in a block, not as a loose transaction
     if (IsCoinBase())
-        return error("AcceptToMemoryPool() : coinbase as individual tx");
+        return DoS(100, error("AcceptToMemoryPool() : coinbase as individual tx"));
 
     // To help v0.1.5 clients who would see it as a negative number
     if ((int64)nLockTime > INT_MAX)
@@ -364,7 +364,7 @@ bool CTransaction::AcceptToMemoryPool(CTxDB& txdb, bool fCheckInputs, bool* pfMi
     // 34 bytes because a TxOut is:
     //   20-byte address + 8 byte bitcoin amount + 5 bytes of ops + 1 byte script length
     if (GetSigOpCount() > nSize / 34 || nSize < 100)
-        return error("AcceptToMemoryPool() : nonstandard transaction");
+        return DoS(10, error("AcceptToMemoryPool() : transaction with out-of-bounds SigOpCount"));
 
     // Rather not work on nonstandard transactions (unless -testnet)
     if (!fTestNet && !IsStandard())
@@ -855,26 +855,28 @@ bool CTransaction::ConnectInputs(CTxDB& txdb, map<uint256, CTxIndex>& mapTestPoo
             }
 
             if (prevout.n >= txPrev.vout.size() || prevout.n >= txindex.vSpent.size())
-                return error("ConnectInputs() : %s prevout.n out of range %d %d %d prev tx %s\n%s", GetHash().ToString().substr(0,10).c_str(), prevout.n, txPrev.vout.size(), txindex.vSpent.size(), prevout.hash.ToString().substr(0,10).c_str(), txPrev.ToString().c_str());
+                return DoS(100, error("ConnectInputs() : %s prevout.n out of range %d %d %d prev tx %s\n%s", GetHash().ToString().substr(0,10).c_str(), prevout.n, txPrev.vout.size(), txindex.vSpent.size(), prevout.hash.ToString().substr(0,10).c_str(), txPrev.ToString().c_str()));
 
             // If prev is coinbase, check that it's matured
             if (txPrev.IsCoinBase())
                 for (CBlockIndex* pindex = pindexBlock; pindex && pindexBlock->nHeight - pindex->nHeight < COINBASE_MATURITY; pindex = pindex->pprev)
                     if (pindex->nBlockPos == txindex.pos.nBlockPos && pindex->nFile == txindex.pos.nFile)
-                        return error("ConnectInputs() : tried to spend coinbase at depth %d", pindexBlock->nHeight - pindex->nHeight);
+                        return DoS(10, error("ConnectInputs() : tried to spend coinbase at depth %d", pindexBlock->nHeight - pindex->nHeight));
 
             // Verify signature
             if (!VerifySignature(txPrev, *this, i))
-                return error("ConnectInputs() : %s VerifySignature failed", GetHash().ToString().substr(0,10).c_str());
+                return DoS(100,error("ConnectInputs() : %s VerifySignature failed", GetHash().ToString().substr(0,10).c_str()));
 
-            // Check for conflicts
+            // Check for conflicts (double-spend)
+            // This doesn't trigger the DoS code on purpose; if it did, it would make it easier
+            // for an attacker to attempt to split the network.
             if (!txindex.vSpent[prevout.n].IsNull())
                 return fMiner ? false : error("ConnectInputs() : %s prev tx already used at %s", GetHash().ToString().substr(0,10).c_str(), txindex.vSpent[prevout.n].ToString().c_str());
 
             // Check for negative or overflow input values
             nValueIn += txPrev.vout[prevout.n].nValue;
             if (!MoneyRange(txPrev.vout[prevout.n].nValue) || !MoneyRange(nValueIn))
-                return error("ConnectInputs() : txin values out of range");
+                return DoS(100, error("ConnectInputs() : txin values out of range"));
 
             // Mark outpoints as spent
             txindex.vSpent[prevout.n] = posThisTx;
@@ -887,17 +889,17 @@ bool CTransaction::ConnectInputs(CTxDB& txdb, map<uint256, CTxIndex>& mapTestPoo
         }
 
         if (nValueIn < GetValueOut())
-            return error("ConnectInputs() : %s value in < value out", GetHash().ToString().substr(0,10).c_str());
+            return DoS(100, error("ConnectInputs() : %s value in < value out", GetHash().ToString().substr(0,10).c_str()));
 
         // Tally transaction fees
         int64 nTxFee = nValueIn - GetValueOut();
         if (nTxFee < 0)
-            return error("ConnectInputs() : %s nTxFee < 0", GetHash().ToString().substr(0,10).c_str());
+            return DoS(100, error("ConnectInputs() : %s nTxFee < 0", GetHash().ToString().substr(0,10).c_str()));
         if (nTxFee < nMinFee)
             return false;
         nFees += nTxFee;
         if (!MoneyRange(nFees))
-            return error("ConnectInputs() : nFees out of range");
+            return DoS(100, error("ConnectInputs() : nFees out of range"));
     }
 
     if (fBlock)
@@ -1240,11 +1242,11 @@ bool CBlock::CheckBlock() const
 
     // Size limits
     if (vtx.empty() || vtx.size() > MAX_BLOCK_SIZE || ::GetSerializeSize(*this, SER_NETWORK) > MAX_BLOCK_SIZE)
-        return error("CheckBlock() : size limits failed");
+        return DoS(100, error("CheckBlock() : size limits failed"));
 
     // Check proof of work matches claimed amount
     if (!CheckProofOfWork(GetHash(), nBits))
-        return error("CheckBlock() : proof of work failed");
+        return DoS(50, error("CheckBlock() : proof of work failed"));
 
     // Check timestamp
     if (GetBlockTime() > GetAdjustedTime() + 2 * 60 * 60)
@@ -1252,23 +1254,23 @@ bool CBlock::CheckBlock() const
 
     // First transaction must be coinbase, the rest must not be
     if (vtx.empty() || !vtx[0].IsCoinBase())
-        return error("CheckBlock() : first tx is not coinbase");
+        return DoS(100, error("CheckBlock() : first tx is not coinbase"));
     for (int i = 1; i < vtx.size(); i++)
         if (vtx[i].IsCoinBase())
-            return error("CheckBlock() : more than one coinbase");
+            return DoS(100, error("CheckBlock() : more than one coinbase"));
 
     // Check transactions
     BOOST_FOREACH(const CTransaction& tx, vtx)
         if (!tx.CheckTransaction())
-            return error("CheckBlock() : CheckTransaction failed");
+            return DoS(tx.nDoS, error("CheckBlock() : CheckTransaction failed"));
 
     // Check that it's not full of nonstandard transactions
     if (GetSigOpCount() > MAX_BLOCK_SIGOPS)
-        return error("CheckBlock() : too many nonstandard transactions");
+        return DoS(100, error("CheckBlock() : out-of-bounds SigOpCount"));
 
     // Check merkleroot
     if (hashMerkleRoot != BuildMerkleTree())
-        return error("CheckBlock() : hashMerkleRoot mismatch");
+        return DoS(100, error("CheckBlock() : hashMerkleRoot mismatch"));
 
     return true;
 }
@@ -1283,13 +1285,13 @@ bool CBlock::AcceptBlock()
     // Get prev block index
     map<uint256, CBlockIndex*>::iterator mi = mapBlockIndex.find(hashPrevBlock);
     if (mi == mapBlockIndex.end())
-        return error("AcceptBlock() : prev block not found");
+        return DoS(10, error("AcceptBlock() : prev block not found"));
     CBlockIndex* pindexPrev = (*mi).second;
     int nHeight = pindexPrev->nHeight+1;
 
     // Check proof of work
     if (nBits != GetNextWorkRequired(pindexPrev))
-        return error("AcceptBlock() : incorrect proof of work");
+        return DoS(100, error("AcceptBlock() : incorrect proof of work"));
 
     // Check timestamp against prev
     if (GetBlockTime() <= pindexPrev->GetMedianTimePast())
@@ -1298,7 +1300,7 @@ bool CBlock::AcceptBlock()
     // Check that all transactions are finalized
     BOOST_FOREACH(const CTransaction& tx, vtx)
         if (!tx.IsFinal(nHeight, GetBlockTime()))
-            return error("AcceptBlock() : contains a non-final transaction");
+            return DoS(10, error("AcceptBlock() : contains a non-final transaction"));
 
     // Check that the block chain matches the known block chain up to a checkpoint
     if (!fTestNet)
@@ -1311,7 +1313,7 @@ bool CBlock::AcceptBlock()
             (nHeight == 118000 && hash != uint256("0x000000000000774a7f8a7a12dc906ddb9e17e75d684f15e00f8767f9e8f36553")) ||
             (nHeight == 134444 && hash != uint256("0x00000000000005b12ffd4cd315cd34ffd4a594f430ac814c91184a0d42d2b0fe")) ||
             (nHeight == 140700 && hash != uint256("0x000000000000033b512028abb90e1626d8b346fd0ed598ac0a3c371138dce2bd")))
-            return error("AcceptBlock() : rejected by checkpoint lockin at %d", nHeight);
+            return DoS(100, error("AcceptBlock() : rejected by checkpoint lockin at %d", nHeight));
 
     // Write block to history file
     if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK)))
@@ -1769,7 +1771,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
     {
         // Each connection can only send one version message
         if (pfrom->nVersion != 0)
+        {
+            pfrom->Misbehaving(1);
             return false;
+        }
 
         int64 nTime;
         CAddress addrMe;
@@ -1857,6 +1862,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
     else if (pfrom->nVersion == 0)
     {
         // Must have a version message before anything else
+        pfrom->Misbehaving(1);
         return false;
     }
 
@@ -1878,7 +1884,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         if (pfrom->nVersion < 31402 && mapAddresses.size() > 1000)
             return true;
         if (vAddr.size() > 1000)
+        {
+            pfrom->Misbehaving(20);
             return error("message addr size() = %d", vAddr.size());
+        }
 
         // Store the new addresses
         CAddrDB addrDB;
@@ -1936,7 +1945,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         vector<CInv> vInv;
         vRecv >> vInv;
         if (vInv.size() > 50000)
+        {
+            pfrom->Misbehaving(20);
             return error("message inv size() = %d", vInv.size());
+        }
 
         CTxDB txdb("r");
         BOOST_FOREACH(const CInv& inv, vInv)
@@ -1965,7 +1977,10 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
         vector<CInv> vInv;
         vRecv >> vInv;
         if (vInv.size() > 50000)
+        {
+            pfrom->Misbehaving(20);
             return error("message getdata size() = %d", vInv.size());
+        }
 
         BOOST_FOREACH(const CInv& inv, vInv)
         {
@@ -2137,6 +2152,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
             printf("storing orphan tx %s\n", inv.hash.ToString().substr(0,10).c_str());
             AddOrphanTx(vMsg);
         }
+        if (tx.nDoS) pfrom->Misbehaving(tx.nDoS);
     }
 
 
@@ -2153,6 +2169,7 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv)
 
         if (ProcessBlock(pfrom, &block))
             mapAlreadyAskedFor.erase(inv);
+        if (block.nDoS) pfrom->Misbehaving(block.nDoS);
     }