OpenAssetTools/src/ZoneLoading/Game/T6/ZoneLoaderFactoryT6.cpp

#include "ZoneLoaderFactoryT6.h"

#include "ContentLoaderT6.h"
#include "Game/GameLanguage.h"
#include "Game/T6/GameAssetPoolT6.h"
#include "Game/T6/GameT6.h"
#include "Game/T6/T6.h"
#include "Game/T6/ZoneConstantsT6.h"
#include "Loading/Processor/ProcessorXChunks.h"
#include "Loading/Steps/StepAddProcessor.h"
#include "Loading/Steps/StepAllocXBlocks.h"
#include "Loading/Steps/StepLoadSignature.h"
#include "Loading/Steps/StepLoadZoneContent.h"
#include "Loading/Steps/StepLoadZoneSizes.h"
#include "Loading/Steps/StepSkipBytes.h"
#include "Loading/Steps/StepVerifyFileName.h"
#include "Loading/Steps/StepVerifyMagic.h"
#include "Loading/Steps/StepVerifySignature.h"
#include "Utils/ClassUtils.h"
#include "Zone/XChunk/XChunkProcessorInflate.h"
#include "Zone/XChunk/XChunkProcessorSalsa20Decryption.h"

#include <cassert>
#include <cstring>
#include <iostream>
#include <memory>

using namespace T6;

namespace
{
    GameLanguage GetZoneLanguage(const std::string& zoneName)
    {
        const auto& languagePrefixes = IGame::GetGameById(GameId::T6)->GetLanguagePrefixes();

        for (const auto& languagePrefix : languagePrefixes)
        {
            if (zoneName.starts_with(languagePrefix.m_prefix))
            {
                return languagePrefix.m_language;
            }
        }

        return GameLanguage::LANGUAGE_NONE;
    }

    bool CanLoad(const ZoneHeader& header, bool* isSecure, bool* isOfficial, bool* isEncrypted)
    {
        assert(isSecure != nullptr);
        assert(isOfficial != nullptr);

        if (header.m_version != ZoneConstants::ZONE_VERSION)
        {
            return false;
        }

        if (!memcmp(header.m_magic, ZoneConstants::MAGIC_SIGNED_TREYARCH, 8))
        {
            *isSecure = true;
            *isOfficial = true;
            *isEncrypted = true;
            return true;
        }

        if (!memcmp(header.m_magic, ZoneConstants::MAGIC_SIGNED_OAT, 8))
        {
            *isSecure = true;
            *isOfficial = false;
            *isEncrypted = true;
            return true;
        }

        if (!memcmp(header.m_magic, ZoneConstants::MAGIC_UNSIGNED, 8))
        {
            *isSecure = false;
            *isOfficial = true;
            *isEncrypted = true;
            return true;
        }

        if (!memcmp(header.m_magic, ZoneConstants::MAGIC_UNSIGNED_SERVER, 8))
        {
            *isSecure = false;
            *isOfficial = true;
            *isEncrypted = false;
            return true;
        }

        return false;
    }

    void SetupBlock(ZoneLoader& zoneLoader)
    {
#define XBLOCK_DEF(name, type) std::make_unique<XBlock>(STR(name), name, type)

        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_TEMP, XBlockType::BLOCK_TYPE_TEMP));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_RUNTIME_VIRTUAL, XBlockType::BLOCK_TYPE_RUNTIME));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_RUNTIME_PHYSICAL, XBlockType::BLOCK_TYPE_RUNTIME));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_DELAY_VIRTUAL, XBlockType::BLOCK_TYPE_DELAY));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_DELAY_PHYSICAL, XBlockType::BLOCK_TYPE_DELAY));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_VIRTUAL, XBlockType::BLOCK_TYPE_NORMAL));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_PHYSICAL, XBlockType::BLOCK_TYPE_NORMAL));
        zoneLoader.AddXBlock(XBLOCK_DEF(T6::XFILE_BLOCK_STREAMER_RESERVE, XBlockType::BLOCK_TYPE_NORMAL));

#undef XBLOCK_DEF
    }

    std::unique_ptr<cryptography::IPublicKeyAlgorithm> SetupRsa(const bool isOfficial)
    {
        if (isOfficial)
        {
            auto rsa = cryptography::CreateRsa(cryptography::HashingAlgorithm::RSA_HASH_SHA256, cryptography::RsaPaddingMode::RSA_PADDING_PSS);

            if (!rsa->SetKey(ZoneConstants::RSA_PUBLIC_KEY_TREYARCH, sizeof(ZoneConstants::RSA_PUBLIC_KEY_TREYARCH)))
            {
                std::cerr << "Invalid public key for signature checking\n";
                return nullptr;
            }

            return rsa;
        }
        else
        {
            assert(false);

            // TODO: Load custom RSA key here
            return nullptr;
        }
    }

    ISignatureProvider* AddAuthHeaderSteps(const bool isSecure, ZoneLoader& zoneLoader, const std::string& fileName)
    {
        // Unsigned zones do not have an auth header
        if (!isSecure)
            return nullptr;

        zoneLoader.AddLoadingStep(step::CreateStepVerifyMagic(ZoneConstants::MAGIC_AUTH_HEADER));
        zoneLoader.AddLoadingStep(step::CreateStepSkipBytes(4)); // Loading Flags which are always zero
        zoneLoader.AddLoadingStep(step::CreateStepVerifyFileName(fileName, 32));

        auto signatureLoadStep = step::CreateStepLoadSignature(256);
        auto* signatureLoadStepPtr = signatureLoadStep.get();
        zoneLoader.AddLoadingStep(std::move(signatureLoadStep));

        return signatureLoadStepPtr;
    }

    ICapturedDataProvider* AddXChunkProcessor(const bool isEncrypted, ZoneLoader& zoneLoader, std::string& fileName)
    {
        ICapturedDataProvider* result = nullptr;
        auto xChunkProcessor = processor::CreateProcessorXChunks(ZoneConstants::STREAM_COUNT, ZoneConstants::XCHUNK_SIZE, ZoneConstants::VANILLA_BUFFER_SIZE);

        if (isEncrypted)
        {
            // If zone is encrypted, the decryption is applied before the decompression. T6 Zones always use Salsa20.
            auto chunkProcessorSalsa20 = std::make_unique<XChunkProcessorSalsa20Decryption>(
                ZoneConstants::STREAM_COUNT, fileName, ZoneConstants::SALSA20_KEY_TREYARCH, sizeof(ZoneConstants::SALSA20_KEY_TREYARCH));
            result = chunkProcessorSalsa20.get();
            xChunkProcessor->AddChunkProcessor(std::move(chunkProcessorSalsa20));
        }

        // Decompress the chunks using zlib
        xChunkProcessor->AddChunkProcessor(std::make_unique<XChunkProcessorInflate>());
        zoneLoader.AddLoadingStep(step::CreateStepAddProcessor(std::move(xChunkProcessor)));

        // If there is encryption, the signed data of the zone is the final hash blocks provided by the Salsa20 IV adaption algorithm
        return result;
    }
} // namespace

std::unique_ptr<ZoneLoader> ZoneLoaderFactory::CreateLoaderForHeader(ZoneHeader& header, std::string& fileName) const
{
    bool isSecure;
    bool isOfficial;
    bool isEncrypted;

    // Check if this file is a supported T6 zone.
    if (!CanLoad(header, &isSecure, &isOfficial, &isEncrypted))
        return nullptr;

    // Create new zone
    auto zone = std::make_unique<Zone>(fileName, 0, IGame::GetGameById(GameId::T6));
    auto* zonePtr = zone.get();
    zone->m_pools = std::make_unique<GameAssetPoolT6>(zonePtr, 0);
    zone->m_language = GetZoneLanguage(fileName);

    // File is supported. Now setup all required steps for loading this file.
    auto zoneLoader = std::make_unique<ZoneLoader>(std::move(zone));

    SetupBlock(*zoneLoader);

    // If file is signed setup a RSA instance.
    auto rsa = isSecure ? SetupRsa(isOfficial) : nullptr;

    // Add steps for loading the auth header which also contain the signature of the zone if it is signed.
    ISignatureProvider* signatureProvider = AddAuthHeaderSteps(isSecure, *zoneLoader, fileName);

    // Setup loading XChunks from the zone from this point on.
    ICapturedDataProvider* signatureDataProvider = AddXChunkProcessor(isEncrypted, *zoneLoader, fileName);

    // Start of the XFile struct
    zoneLoader->AddLoadingStep(step::CreateStepLoadZoneSizes());
    zoneLoader->AddLoadingStep(step::CreateStepAllocXBlocks());

    // Start of the zone content
    zoneLoader->AddLoadingStep(step::CreateStepLoadZoneContent(
        [&zonePtr](ZoneInputStream& stream)
        {
            return std::make_unique<ContentLoader>(*zonePtr, stream);
        },
        32u,
        ZoneConstants::OFFSET_BLOCK_BIT_COUNT,
        ZoneConstants::INSERT_BLOCK,
        zonePtr->Memory()));

    if (isSecure)
    {
        zoneLoader->AddLoadingStep(step::CreateStepVerifySignature(std::move(rsa), signatureProvider, signatureDataProvider));
    }

    return zoneLoader;
}