Constructing spending signatures

1001}
1002
1003const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR = DummySignatureCreator(32, 32);
1004const BaseSignatureCreator& DUMMY_MAXIMUM_SIGNATURE_CREATOR = DummySignatureCreator(33, 32);
1005
1006bool IsSegWitOutput(const SigningProvider& provider, const CScript& script)
1007{
1008    int version;
1009    valtype program;
1010    if (script.IsWitnessProgram(version, program)) return true;
1011    if (script.IsPayToScriptHash()) {
1012        std::vector<valtype> solutions;
1013        auto whichtype = Solver(script, solutions);
1014        if (whichtype == TxoutType::SCRIPTHASH) {
1015            auto h160 = uint160(solutions[0]);
1016            CScript subscript;
1017            if (provider.GetCScript(CScriptID{h160}, subscript)) {
1018                if (subscript.IsWitnessProgram(version, program)) return true;
1019            }
1020        }
1021    }
1022    return false;
1023}
1024
1025bool SignTransaction(CMutableTransaction& mtx, const SigningProvider* keystore, const std::map<COutPoint, Coin>& coins, const SignOptions& options, std::map<int, bilingual_str>& input_errors)
1026{
1027    bool fHashSingle = ((options.sighash_type & ~SIGHASH_ANYONECANPAY) == SIGHASH_SINGLE);
1028
1029    // Use CTransaction for the constant parts of the
1030    // transaction to avoid rehashing.
1031    const CTransaction txConst(mtx);
1032
1033    PrecomputedTransactionData txdata;
1034    std::vector<CTxOut> spent_outputs;
1035    for (unsigned int i = 0; i < mtx.vin.size(); ++i) {
1036        CTxIn& txin = mtx.vin[i];
1037        auto coin = coins.find(txin.prevout);
1038        if (coin == coins.end() || coin->second.IsSpent()) {
1039            txdata.Init(txConst, /*spent_outputs=*/{}, /*force=*/true);
1040            break;
1041        } else {
1042            spent_outputs.emplace_back(coin->second.out.nValue, coin->second.out.scriptPubKey);
1043        }
1044    }
1045    if (spent_outputs.size() == mtx.vin.size()) {
1046        txdata.Init(txConst, std::move(spent_outputs), true);
1047    }
1048
1049    // Sign what we can:
1050    for (unsigned int i = 0; i < mtx.vin.size(); ++i) {
1051        CTxIn& txin = mtx.vin[i];
1052        auto coin = coins.find(txin.prevout);
1053        if (coin == coins.end() || coin->second.IsSpent()) {
1054            input_errors[i] = _("Input not found or already spent");
1055            continue;
1056        }
1057        const CScript& prevPubKey = coin->second.out.scriptPubKey;
1058        const CAmount& amount = coin->second.out.nValue;
1059
1060        SignatureData sigdata = DataFromTransaction(mtx, i, coin->second.out);
1061        // Only sign SIGHASH_SINGLE if there's a corresponding output:
1062        if (!fHashSingle || (i < mtx.vout.size())) {
1063            ProduceSignature(*keystore, MutableTransactionSignatureCreator(mtx, i, amount, &txdata, options), prevPubKey, sigdata);
1064        }
1065
1066        UpdateInput(txin, sigdata);
1067
1068        // amount must be specified for valid segwit signature
1069        if (amount == MAX_MONEY && !txin.scriptWitness.IsNull()) {
1070            input_errors[i] = _("Missing amount");
1071            continue;
1072        }
1073
1074        ScriptError serror = SCRIPT_ERR_OK;
1075        if (!sigdata.complete && !VerifyScript(txin.scriptSig, prevPubKey, &txin.scriptWitness, STANDARD_SCRIPT_VERIFY_FLAGS, TransactionSignatureChecker(&txConst, i, amount, txdata, MissingDataBehavior::FAIL), &serror)) {
1076            if (serror == SCRIPT_ERR_INVALID_STACK_OPERATION) {
1077                // Unable to sign input and verification failed (possible attempt to partially sign).
1078                input_errors[i] = Untranslated("Unable to sign input, invalid stack size (possibly missing key)");
1079            } else if (serror == SCRIPT_ERR_SIG_NULLFAIL) {
1080                // Verification failed (possibly due to insufficient signatures).
1081                input_errors[i] = Untranslated("CHECK(MULTI)SIG failing with non-zero signature (possibly need more signatures)");
1082            } else {
1083                input_errors[i] = Untranslated(ScriptErrorString(serror));
1084            }
1085        } else {
1086            // If this input succeeds, make sure there is no error set for it
1087            input_errors.erase(i);
1088        }
1089    }
1090    return input_errors.empty();
1091}
1092