Use RPC calls to check bitcoin blocks are valid and confirmed

src/script/interpreter.cpp

@@ -20,6 +20,11 @@
 #include "streams.h"
 #include "uint256.h"
 #include "utilstrencodings.h"
+#include "util.h"
+
+#ifndef BITCOIN_SCRIPT_NO_CALLRPC
+#include "callrpc.h"
+#endif
 
 using namespace std;
 
@@ -1211,7 +1216,10 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                                 if (withdrawOutput.scriptPubKey != expectedWithdrawScriptPubKey)
                                     return set_error(serror, SCRIPT_ERR_WITHDRAW_VERIFY_OUTPUT);
 
-                                //TODO: Check that we're spending from a valid, buried bitcoin block
+#ifndef BITCOIN_SCRIPT_NO_CALLRPC
+                                if (!GetBoolArg("-blindtrust", true) && !checker.IsConfirmedBitcoinBlock(genesishash, merkleBlock.header.GetHash(), flags & SCRIPT_VERIFY_INCREASE_CONFIRMATIONS_REQUIRED))
+                                    return set_error(serror, SCRIPT_ERR_WITHDRAW_VERIFY_BLOCKCONFIRMED);
+#endif
                             } catch (std::exception& e) {
                                 // Probably invalid encoding of something which was deserialized
                                 return set_error(serror, SCRIPT_ERR_WITHDRAW_VERIFY_FORMAT);
@@ -1582,6 +1590,15 @@ CAmount TransactionSignatureChecker::GetValueInPrevIn() const
     return amountPreviousInput;
 }
 
+bool TransactionSignatureChecker::IsConfirmedBitcoinBlock(const uint256& genesishash, const uint256& hash, bool fConservativeConfirmationRequirements) const
+{
+#ifndef BITCOIN_SCRIPT_NO_CALLRPC
+    return ::IsConfirmedBitcoinBlock(genesishash, hash, fConservativeConfirmationRequirements ? 10 : 8);
+#else
+    return true;
+#endif
+}
+
 static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, const std::vector<unsigned char>& program, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
 {
     vector<vector<unsigned char> > stack;

src/script/interpreter.h

@@ -111,6 +111,10 @@ enum
     // Execute sidechain-related opcodes instead of treating them as NOPs
     //
     SCRIPT_VERIFY_WITHDRAW = (1U << 16),
+
+    // Dirty hack to require a higher bar of bitcoin block confirmation in mempool
+    //
+    SCRIPT_VERIFY_INCREASE_CONFIRMATIONS_REQUIRED = (1U << 17)
 };
 
 bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);
@@ -161,6 +165,11 @@ public:
         return -1;
     }
 
+    virtual bool IsConfirmedBitcoinBlock(const uint256& genesishash, const uint256& hash, bool fConservativeConfirmationRequirements) const
+    {
+        return false;
+    }
+
     virtual ~BaseSignatureChecker() {}
 };
 
@@ -203,6 +212,7 @@ public:
     COutPoint GetPrevOut() const;
     CAmount GetValueIn() const;
     CAmount GetValueInPrevIn() const;
+    bool IsConfirmedBitcoinBlock(const uint256& genesishash, const uint256& hash, bool fConservativeConfirmationRequirements) const;
 };
 
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = NULL);

src/script/script_error.cpp

@@ -95,6 +95,8 @@ const char* ScriptErrorString(const ScriptError serror)
             return "Withdraw proof validation failed - locking transaction misformatted";
         case SCRIPT_ERR_WITHDRAW_VERIFY_OUTPUT:
             return "Withdraw proof validation failed - output does not match expected";
+        case SCRIPT_ERR_WITHDRAW_VERIFY_BLOCKCONFIRMED:
+            return "Withdraw proof validation failed - lock block was not sufficiently confirmed on sending chain";
         case SCRIPT_ERR_UNKNOWN_ERROR:
         case SCRIPT_ERR_ERROR_COUNT:
         default: break;

src/script/script_error.h

@@ -69,6 +69,7 @@ typedef enum ScriptError_t
     SCRIPT_ERR_WITHDRAW_VERIFY_BLOCK,
     SCRIPT_ERR_WITHDRAW_VERIFY_LOCKTX,
     SCRIPT_ERR_WITHDRAW_VERIFY_OUTPUT,
+    SCRIPT_ERR_WITHDRAW_VERIFY_BLOCKCONFIRMED,
 
     SCRIPT_ERR_ERROR_COUNT
 } ScriptError;