比特币源码阅读(交易-CTransaction序列化和反序列化)

隔离验证和非隔离验证存在不一样的地方：
隔离验证多出来的：
s << vinDummy;
s << flags;
s << tx.vin[i].scriptWitness.stack //vin.size()个

//交易序列化
template<typename Stream, typename TxType>
inline void SerializeTransaction(const TxType& tx, Stream& s) {
    const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS); //版本为允许隔离验证的版本

    s << tx.nVersion; //nVersion
    unsigned char flags = 0;
    // Consistency check
    if (fAllowWitness) {
        /* Check whether witnesses need to be serialized. */
        if (tx.HasWitness()) {
            flags |= 1; //有隔离验证
        }
    }
    if (flags) {
        /* Use extended format in case witnesses are to be serialized. */
        std::vector<CTxIn> vinDummy;
        s << vinDummy; //这个用来干什么？
        s << flags; //flag
    }
    s << tx.vin;
    s << tx.vout;
    if (flags & 1) {
        for (size_t i = 0; i < tx.vin.size(); i++) {
            s << tx.vin[i].scriptWitness.stack; //隔离验证脚本
        }
    }
    s << tx.nLockTime;
}

反序列化

template<typename Stream, typename TxType>
inline void UnserializeTransaction(TxType& tx, Stream& s) {
    const bool fAllowWitness = !(s.GetVersion() & SERIALIZE_TRANSACTION_NO_WITNESS);

    s >> tx.nVersion; //读出version
    unsigned char flags = 0;
    tx.vin.clear(); //vin clear
    tx.vout.clear(); //vout clear
    /* Try to read the vin. In case the dummy is there, this will be read as an empty vector. */
    s >> tx.vin;
    if (tx.vin.size() == 0 && fAllowWitness) {
        /* We read a dummy or an empty vin. */
        s >> flags;
        if (flags != 0) {
            s >> tx.vin;
            s >> tx.vout;
        }
    } else {
        /* We read a non-empty vin. Assume a normal vout follows. */
        s >> tx.vout;
    }
    if ((flags & 1) && fAllowWitness) {
        /* The witness flag is present, and we support witnesses. */
        flags ^= 1;
        for (size_t i = 0; i < tx.vin.size(); i++) {
            s >> tx.vin[i].scriptWitness.stack;
        }
    }
    if (flags) {
        /* Unknown flag in the serialization */
        throw std::ios_base::failure("Unknown transaction optional data");
    }
    s >> tx.nLockTime;
}