[build] Move CheckTransaction from lib_server to lib_consensus

CheckTransaction is a context-free function that does not require access
to the blockchain or mempool. Move it from src/consensus/tx_verify in
lib_server to a new unit src/consensus/tx_check in lib_consensus so that
it can be called by non-server libraries.

4 files changed, 77 insertions, 52 deletions

diff --git a/src/consensus/tx_check.cpp b/src/consensus/tx_check.cpp
new file mode 100644
index 0000000000..61a607ef7f
--- /dev/null
+++ b/src/consensus/tx_check.cpp
@@ -0,0 +1,57 @@
+// Copyright (c) 2017-2018 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 <consensus/tx_check.h>
+
+#include <primitives/transaction.h>
+#include <consensus/validation.h>
+
+bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fCheckDuplicateInputs)
+{
+    // Basic checks that don't depend on any context
+    if (tx.vin.empty())
+        return state.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty");
+    if (tx.vout.empty())
+        return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
+    // Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
+    if (::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT)
+        return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
+
+    // Check for negative or overflow output values
+    CAmount nValueOut = 0;
+    for (const auto& txout : tx.vout)
+    {
+        if (txout.nValue < 0)
+            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative");
+        if (txout.nValue > MAX_MONEY)
+            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge");
+        nValueOut += txout.nValue;
+        if (!MoneyRange(nValueOut))
+            return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
+    }
+
+    // Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
+    if (fCheckDuplicateInputs) {
+        std::set<COutPoint> vInOutPoints;
+        for (const auto& txin : tx.vin)
+        {
+            if (!vInOutPoints.insert(txin.prevout).second)
+                return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
+        }
+    }
+
+    if (tx.IsCoinBase())
+    {
+        if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
+            return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
+    }
+    else
+    {
+        for (const auto& txin : tx.vin)
+            if (txin.prevout.IsNull())
+                return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null");
+    }
+
+    return true;
+}
diff --git a/src/consensus/tx_check.h b/src/consensus/tx_check.h
new file mode 100644
index 0000000000..bcfdf36bf9
--- /dev/null
+++ b/src/consensus/tx_check.h
@@ -0,0 +1,20 @@
+// Copyright (c) 2017-2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_CONSENSUS_TX_CHECK_H
+#define BITCOIN_CONSENSUS_TX_CHECK_H
+
+/**
+ * Context-independent transaction checking code that can be called outside the
+ * bitcoin server and doesn't depend on chain or mempool state. Transaction
+ * verification code that does call server functions or depend on server state
+ * belongs in tx_verify.h/cpp instead.
+ */
+
+class CTransaction;
+class CValidationState;
+
+bool CheckTransaction(const CTransaction& tx, CValidationState& state, bool fCheckDuplicateInputs=true);
+
+#endif // BITCOIN_CONSENSUS_TX_CHECK_H
diff --git a/src/consensus/tx_verify.cpp b/src/consensus/tx_verify.cpp
index 0a7eacfb91..fbbbcfd040 100644
--- a/src/consensus/tx_verify.cpp
+++ b/src/consensus/tx_verify.cpp
@@ -156,55 +156,6 @@ int64_t GetTransactionSigOpCost(const CTransaction& tx, const CCoinsViewCache& i
     return nSigOps;
 }
 
-bool CheckTransaction(const CTransaction& tx, CValidationState &state, bool fCheckDuplicateInputs)
-{
-    // Basic checks that don't depend on any context
-    if (tx.vin.empty())
-        return state.DoS(10, false, REJECT_INVALID, "bad-txns-vin-empty");
-    if (tx.vout.empty())
-        return state.DoS(10, false, REJECT_INVALID, "bad-txns-vout-empty");
-    // Size limits (this doesn't take the witness into account, as that hasn't been checked for malleability)
-    if (::GetSerializeSize(tx, PROTOCOL_VERSION | SERIALIZE_TRANSACTION_NO_WITNESS) * WITNESS_SCALE_FACTOR > MAX_BLOCK_WEIGHT)
-        return state.DoS(100, false, REJECT_INVALID, "bad-txns-oversize");
-
-    // Check for negative or overflow output values
-    CAmount nValueOut = 0;
-    for (const auto& txout : tx.vout)
-    {
-        if (txout.nValue < 0)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-negative");
-        if (txout.nValue > MAX_MONEY)
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-vout-toolarge");
-        nValueOut += txout.nValue;
-        if (!MoneyRange(nValueOut))
-            return state.DoS(100, false, REJECT_INVALID, "bad-txns-txouttotal-toolarge");
-    }
-
-    // Check for duplicate inputs - note that this check is slow so we skip it in CheckBlock
-    if (fCheckDuplicateInputs) {
-        std::set<COutPoint> vInOutPoints;
-        for (const auto& txin : tx.vin)
-        {
-            if (!vInOutPoints.insert(txin.prevout).second)
-                return state.DoS(100, false, REJECT_INVALID, "bad-txns-inputs-duplicate");
-        }
-    }
-
-    if (tx.IsCoinBase())
-    {
-        if (tx.vin[0].scriptSig.size() < 2 || tx.vin[0].scriptSig.size() > 100)
-            return state.DoS(100, false, REJECT_INVALID, "bad-cb-length");
-    }
-    else
-    {
-        for (const auto& txin : tx.vin)
-            if (txin.prevout.IsNull())
-                return state.DoS(10, false, REJECT_INVALID, "bad-txns-prevout-null");
-    }
-
-    return true;
-}
-
 bool Consensus::CheckTxInputs(const CTransaction& tx, CValidationState& state, const CCoinsViewCache& inputs, int nSpendHeight, CAmount& txfee)
 {
     // are the actual inputs available?
diff --git a/src/consensus/tx_verify.h b/src/consensus/tx_verify.h
index 0519cef8c0..3519fc555d 100644
--- a/src/consensus/tx_verify.h
+++ b/src/consensus/tx_verify.h
@@ -17,9 +17,6 @@ class CValidationState;
 
 /** Transaction validation functions */
 
-/** Context-independent validity checks */
-bool CheckTransaction(const CTransaction& tx, CValidationState& state, bool fCheckDuplicateInputs=true);
-
 namespace Consensus {
 /**
  * Check whether all inputs of this transaction are valid (no double spends and amounts)