SRUP_Simple.cpp

//
// Created by AJ Poulter on 11/05/2018.
//

#include "SRUP_Simple.h"

bool SRUP_MSG_SIMPLE::Serialize(bool preSign)
{
    // As we're using dynamic memory - and only storing / sending the length of the data we have
    // we need to know how long all of the fields are so that we can unmarshall the data at
    // the other end...

    const uint16_t header_size = 18; // Two-bytes for the main header - plus 8 for the sequence ID & 8 for the sender ID...
    const uint8_t field_length_size = 2;

    // We need the number of variable length fields - including the m_sig_len...
    // ... this can't be const as we need to change it depending on whether or not we're in pre-sign.
    // (If we are we need to reduce it by one for the unused m_sig_len
    uint8_t var_length_field_count = 2;

    uint32_t serial_len;
    uint32_t p = 0;

    uint8_t *msb;
    uint8_t *lsb;

    msb = new uint8_t[1];
    lsb = new uint8_t[1];

    // Now check that we have a sequence ID...
    if (m_sequence_ID == nullptr)
    {
        delete[] msb;
        delete[] lsb;
        return false;
    }

    // ...and a sender ID
    if (m_sender_ID == nullptr)
    {
        delete[] msb;
        delete[] lsb;
        return false;
    }

    // If we're calling this as a prelude to signing / verifying then we need to exclude the signature data from the
    // serial data we generate...

    if (preSign)
    {
        serial_len = m_token_len;
        var_length_field_count--;
    }
    else
        serial_len = m_sig_len + m_token_len;


    m_serial_length = serial_len + header_size + (field_length_size * var_length_field_count);

    delete[] m_serialized;

    m_serialized = new uint8_t[m_serial_length];
    std::memset(m_serialized, 0, m_serial_length);

    // The first two fields are fixed length (1 byte each).
    std::memcpy(m_serialized, m_version, 1);
    p+=1;
    std::memcpy(m_serialized + p, m_msgtype, 1);
    p+=1;

    // Now we need to add the Sequence ID (uint64_t)
    // See SRUP_Init.cpp for details...
    for (int x=0;x<8;x++)
    {
        uint8_t byte;
        byte = getByteVal(*m_sequence_ID, x);
        std::memcpy(m_serialized + p, &byte, 1);
        p+=1;
    }

    // ...and the same for the sender ID
    for (int x=0;x<8;x++)
    {
        uint8_t byte;
        byte = getByteVal(*m_sender_ID, x);
        std::memcpy(m_serialized + p, &byte, 1);
        p+=1;
    }

    // All of the other fields need their length to be specified...

    // Token...
    encodeLength(lsb, msb, m_token_len);
    std::memcpy(m_serialized + p, msb, 1);
    p+=1;
    std::memcpy(m_serialized + p, lsb, 1);
    p+=1;
    std::memcpy(m_serialized + p, m_token, m_token_len);
    p+=m_token_len;

    // If we're executing Serialize as a part of generating the signature - we can't marshall the signature
    // as we haven't calculated it yet. So only do the signature if we're not in preSign

    if (!preSign)
    {
        if (m_signature == nullptr)
            return false;
        else
        {
            if (m_sig_len == 0)
                return false;
            else
            {
                encodeLength(lsb, msb, m_sig_len);
                std::memcpy(m_serialized + p, msb, 1);
                p += 1;
                std::memcpy(m_serialized + p, lsb, 1);
                p += 1;
                std::memcpy(m_serialized + p, m_signature, m_sig_len);
                // p += m_sig_len; - the value is not used since this is the final operation
            }
        }
    }

    delete[] msb;
    delete[] lsb;

    // If we're in preSign we don't have a real value for m_serialized - so copy the data to m_unsigned_message
    // and discard (and reset) m_serialized & m_serial_length...
    if (preSign)
    {
        delete[] m_unsigned_message;
        m_unsigned_message = new unsigned char[m_serial_length];

        std::memcpy(m_unsigned_message, m_serialized, m_serial_length);
        m_unsigned_length = m_serial_length;

        m_serial_length = 0;
        delete[] m_serialized;
        m_serialized= nullptr;
    }

    m_is_serialized = true;
    return true;
}

uint32_t SRUP_MSG_SIMPLE::SerializedLength()
{
    if (!m_is_serialized)
        Serialize(false);

    return m_serial_length;
}

unsigned char *SRUP_MSG_SIMPLE::Serialized()
{
    if (Serialize(false))
        return m_serialized;
    else
        return nullptr;
}

bool SRUP_MSG_SIMPLE::DeSerialize(const unsigned char* serial_data)
{
    uint16_t x;
    uint32_t p=0;
    uint8_t bytes[2];

    // We need to unmarshall the data to reconstruct the object...
    // We can start with the two bytes for the header.
    // One for the version - and one for the message type.

    std::memcpy(m_version, (uint8_t*) serial_data, 1);
    p+=1;
    std::memcpy(m_msgtype, (uint8_t*) serial_data + p, 1);
    p+=1;

    // Now we have to unmarshall the sequence ID...
    uint8_t sid_bytes[8];
    for (unsigned char & sid_byte : sid_bytes)
    {
        std::memcpy(&sid_byte, (uint8_t*) serial_data + p, 1);
        ++p;
    }

    // ... then we copy them into m_sequence_ID
    if (m_sequence_ID != nullptr)
        delete(m_sequence_ID);
    m_sequence_ID = new uint64_t;
    std::memcpy(m_sequence_ID, sid_bytes, 8);

    // ...and also for the sender_ID
    uint8_t snd_bytes[8];
    for (unsigned char & snd_byte : snd_bytes)
    {
        std::memcpy(&snd_byte, (uint8_t*) serial_data + p, 1);
        ++p;
    }

    if (m_sender_ID!= nullptr)
        delete(m_sender_ID);
    m_sender_ID = new uint64_t;
    std::memcpy(m_sender_ID, snd_bytes, 8);

    // Now we have two-bytes for the size of the token ... and x bytes for the token
    std::memcpy(bytes, serial_data + p, 2);
    x = decodeLength(bytes);
    p+=2;
    delete[] m_token;
    m_token = new uint8_t[x+1];
    std::memcpy(m_token, (char*) serial_data + p, x);
    m_token_len = x;
    p+=x;

    // The next two bytes are the size of the signature...
    std::memcpy(bytes, serial_data + p, 2);
    x = decodeLength(bytes);
    p+=2;

    m_sig_len = x;

    // The next x bytes are the value of the signature.
    delete[] m_signature;
    m_signature = new unsigned char[x];
    std::memcpy(m_signature, serial_data + p, x);

    return true;
}

bool SRUP_MSG_SIMPLE::DataCheck()
{
    if ((m_token == nullptr) || (m_sequence_ID == nullptr) || (m_sender_ID == nullptr))
        return false;
    else
        return true;
}