Use RPC calls to check bitcoin blocks are valid and confirmed

src/callrpc.cpp

@@ -10,7 +10,7 @@ using namespace json_spirit;
 
 #define _(x) std::string(x) /* Keep the _() around in case gettext or such will be used later to translate non-UI */
 
-Object CallRPC(const string& strMethod, const Array& params)
+Object CallRPC(const string& strMethod, const Array& params, string port)
 {
     if (mapArgs["-rpcuser"] == "" && mapArgs["-rpcpassword"] == "")
         throw runtime_error(strprintf(
@@ -27,7 +27,9 @@ Object CallRPC(const string& strMethod, const Array& params)
     SSLIOStreamDevice<asio::ip::tcp> d(sslStream, fUseSSL);
     iostreams::stream< SSLIOStreamDevice<asio::ip::tcp> > stream(d);
 
-    const bool fConnected = d.connect(GetArg("-rpcconnect", "127.0.0.1"), GetArg("-rpcport", itostr(BaseParams().RPCPort())));
+    if (port == "")
+        port = GetArg("-rpcport", itostr(BaseParams().RPCPort()));
+    const bool fConnected = d.connect(GetArg("-rpcconnect", "127.0.0.1"), port);
     if (!fConnected)
         throw CConnectionFailed("couldn't connect to server");
 
@@ -67,3 +69,26 @@ Object CallRPC(const string& strMethod, const Array& params)
 
     return reply;
 }
+
+bool IsConfirmedBitcoinBlock(const uint256& hash, int nMinConfirmationDepth)
+{
+    try {
+        Array params;
+        params.push_back(hash.GetHex());
+        Object reply = CallRPC("getblock", params, GetArg("-rpcconnectport", "18332"));
+        if (find_value(reply, "error").type() != null_type)
+            return false;
+        Value result = find_value(reply, "result");
+        if (result.type() != obj_type)
+            return false;
+        result = find_value(result.get_obj(), "confirmations");
+        return result.type() == int_type && result.get_int64() >= nMinConfirmationDepth;
+    } catch (CConnectionFailed& e) {
+        LogPrintf("ERROR: Lost connection to bitcoind RPC, you will want to restart after fixing this!\n");
+        return false;
+    } catch (...) {
+        LogPrintf("ERROR: Failure connecting to bitcoind RPC, you will want to restart after fixing this!\n");
+        return false;
+    }
+    return true;
+}

src/callrpc.h

@@ -8,6 +8,7 @@
 
 #include "rpcclient.h"
 #include "rpcprotocol.h"
+#include "uint256.h"
 
 #include <string>
 
@@ -25,6 +26,7 @@ public:
 
 };
 
-json_spirit::Object CallRPC(const std::string& strMethod, const json_spirit::Array& params);
+json_spirit::Object CallRPC(const std::string& strMethod, const json_spirit::Array& params, std::string port="");
+bool IsConfirmedBitcoinBlock(const uint256& hash, int nMinConfirmationDepth);
 
 #endif // BITCOIN_CALLRPC_H

src/script/interpreter.cpp

@@ -8,6 +8,9 @@
 #include <secp256k1.h>
 
 #define FEDERATED_PEG_SIDECHAIN_ONLY
+#ifdef FEDERATED_PEG_SIDECHAIN_ONLY
+#include "callrpc.h"
+#endif
 
 #include "primitives/transaction.h"
 #include "crypto/ripemd160.h"
@@ -23,6 +26,7 @@
 #include "streams.h"
 #include "uint256.h"
 #include "utilstrencodings.h"
+#include "util.h"
 
 using namespace std;
 
@@ -1285,7 +1289,8 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                                     return set_error(serror, SCRIPT_ERR_WITHDRAW_VERIFY_SECONDSCRIPT);
 
 #ifdef FEDERATED_PEG_SIDECHAIN_ONLY
-                                //TODO: Check that we're spending from a valid, buried bitcoin block
+                                if (!GetBoolArg("-blindtrust", true) && !checker.IsConfirmedBitcoinBlock(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
@@ -1712,6 +1717,13 @@ CAmount TransactionSignatureChecker::GetValueInPrevIn() const
     return nInMinusOneValue;
 }
 
+#ifdef FEDERATED_PEG_SIDECHAIN_ONLY
+bool TransactionSignatureChecker::IsConfirmedBitcoinBlock(const uint256& hash, bool fConservativeConfirmationRequirements) const
+{
+    return ::IsConfirmedBitcoinBlock(hash, fConservativeConfirmationRequirements ? 10 : 8);
+}
+#endif
+
 bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror)
 {
     set_error(serror, SCRIPT_ERR_UNKNOWN_ERROR);

src/script/interpreter.h

@@ -82,6 +82,9 @@ enum
 
     // Execute sidechain-related opcodes instead of treating them as NOPs
     SCRIPT_VERIFY_WITHDRAW = (1U << 11),
+
+    // Dirty hack to require a higher bar of bitcoin block confirmation in mempool
+    SCRIPT_VERIFY_INCREASE_CONFIRMATIONS_REQUIRED = (1U << 12)
 };
 
 uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
@@ -117,6 +120,14 @@ public:
         return -1;
     }
 
+#define FEDERATED_PEG_SIDECHAIN_ONLY
+#ifdef FEDERATED_PEG_SIDECHAIN_ONLY
+    virtual bool IsConfirmedBitcoinBlock(const uint256& hash, bool fConservativeConfirmationRequirements) const
+    {
+        return false;
+    }
+#endif
+
     virtual ~BaseSignatureChecker() {}
 };
 
@@ -157,6 +168,9 @@ public:
     CAmount GetValueIn() const;
     CAmount GetValueInPrevIn() const;
     CAmount GetTransactionFee() const;
+#ifdef FEDERATED_PEG_SIDECHAIN_ONLY
+    bool IsConfirmedBitcoinBlock(const uint256& hash, bool fConservativeConfirmationRequirements) const;
+#endif
 };
 
 bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* error = NULL);

src/script/script_error.cpp

@@ -79,6 +79,8 @@ const char* ScriptErrorString(const ScriptError serror)
             return "Withdraw proof validation failed - locktime was not set correctly";
         case SCRIPT_ERR_WITHDRAW_VERIFY_SECONDSCRIPT:
             return "Withdraw proof validation failed - second script validation failed";
+        case SCRIPT_ERR_WITHDRAW_VERIFY_BLOCKCONFIRMED:
+            return "Withdraw proof validation failed - lock block was not sufficiently confirmed on sending chain";
         case SCRIPT_ERR_REORG_VERIFY_FORMAT:
             return "Reorg/Fraud proof validation failed - invalid proof format";
         case SCRIPT_ERR_REORG_VERIFY_FRAUD_BLOCK:

src/script/script_error.h

@@ -58,6 +58,7 @@ typedef enum ScriptError_t
     SCRIPT_ERR_WITHDRAW_VERIFY_OUTPUT,
     SCRIPT_ERR_WITHDRAW_VERIFY_LOCKTIME,
     SCRIPT_ERR_WITHDRAW_VERIFY_SECONDSCRIPT,
+    SCRIPT_ERR_WITHDRAW_VERIFY_BLOCKCONFIRMED,
     SCRIPT_ERR_REORG_VERIFY_FORMAT,
     SCRIPT_ERR_REORG_VERIFY_FRAUD_BLOCK,
     SCRIPT_ERR_REORG_VERIFY_FRAUD_ORIG_BLOCK,

src/script/standard.h

@@ -51,7 +51,8 @@ static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY
                                                          SCRIPT_VERIFY_NULLDUMMY |
                                                          SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS |
                                                          SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY |
-                                                         SCRIPT_VERIFY_CHECKSEQUENCEVERIFY;
+                                                         SCRIPT_VERIFY_CHECKSEQUENCEVERIFY |
+                                                         SCRIPT_VERIFY_INCREASE_CONFIRMATIONS_REQUIRED;
 
 /** For convenience, standard but not mandatory verify flags. */
 static const unsigned int STANDARD_NOT_MANDATORY_VERIFY_FLAGS = STANDARD_SCRIPT_VERIFY_FLAGS & ~MANDATORY_SCRIPT_VERIFY_FLAGS;