#include "stdafx.h"

#include "GateKeeper.h"

#include "pEpCOMServerAdapter.h"

#include "utf8_helper.h"

using namespace std;

// https://gist.github.com/mcdurdin/5626617

struct PUBLIC_KEY_VALUES {

    BLOBHEADER blobheader;

    RSAPUBKEY rsapubkey;

    BYTE modulus[4096];

};

static void ReverseMemCopy(

    _Out_ BYTE       *pbDest,

    _In_  BYTE const *pbSource,

    _In_  DWORD       cb

    )

{

    for (DWORD i = 0; i < cb; i++) {

        pbDest[cb - 1 - i] = pbSource[i];

    }

}

static NTSTATUS ImportRsaPublicKey(

    _In_ BCRYPT_ALG_HANDLE  hAlg,    // CNG provider

    _In_ PUBLIC_KEY_VALUES *pKey,    // Pointer to the RSAPUBKEY blob.

    _In_ BCRYPT_KEY_HANDLE *phKey    // Receives a handle the imported public key.

    )

{

    NTSTATUS hr = 0;

    BYTE *pbPublicKey = NULL;

    DWORD cbKey = 0;

    // Layout of the RSA public key blob:

    //  +----------------------------------------------------------------+

    //  |     BCRYPT_RSAKEY_BLOB    | BE( dwExp ) |   BE( Modulus )      |

    //  +----------------------------------------------------------------+

    //

    //  sizeof(BCRYPT_RSAKEY_BLOB)       cbExp           cbModulus 

    //  <--------------------------><------------><---------------------->

    //

    //   BE = Big Endian Format                                                     

    DWORD cbModulus = (pKey->rsapubkey.bitlen + 7) / 8;

    DWORD dwExp = pKey->rsapubkey.pubexp;

    DWORD cbExp = (dwExp & 0xFF000000) ? 4 :

        (dwExp & 0x00FF0000) ? 3 :

        (dwExp & 0x0000FF00) ? 2 : 1;

    BCRYPT_RSAKEY_BLOB *pRsaBlob;

    PBYTE pbCurrent;

    if (!SUCCEEDED(hr = DWordAdd(cbModulus, sizeof(BCRYPT_RSAKEY_BLOB), &cbKey))) {

        goto cleanup;

    }

    cbKey += cbExp;

    pbPublicKey = (PBYTE) CoTaskMemAlloc(cbKey);

    if (pbPublicKey == NULL) {

        hr = E_OUTOFMEMORY;

        goto cleanup;

    }

    ZeroMemory(pbPublicKey, cbKey);

    pRsaBlob = (BCRYPT_RSAKEY_BLOB *) (pbPublicKey);

    //

    // Make the Public Key Blob Header

    //

    pRsaBlob->Magic = BCRYPT_RSAPUBLIC_MAGIC;

    pRsaBlob->BitLength = pKey->rsapubkey.bitlen;

    pRsaBlob->cbPublicExp = cbExp;

    pRsaBlob->cbModulus = cbModulus;

    pRsaBlob->cbPrime1 = 0;

    pRsaBlob->cbPrime2 = 0;

    pbCurrent = (PBYTE) (pRsaBlob + 1);

    //

    // Copy pubExp Big Endian 

    //

    ReverseMemCopy(pbCurrent, (PBYTE) &dwExp, cbExp);

    pbCurrent += cbExp;

    //

    // Copy Modulus Big Endian 

    //

    ReverseMemCopy(pbCurrent, pKey->modulus, cbModulus);

    //

    // Import the public key

    //

    hr = BCryptImportKeyPair(hAlg, NULL, BCRYPT_RSAPUBLIC_BLOB, phKey, (PUCHAR) pbPublicKey, cbKey, 0);

cleanup:

    CoTaskMemFree(pbPublicKey);

    return hr;

}

namespace pEp {

    const LPCTSTR GateKeeper::plugin_reg_path = _T("Software\\Microsoft\\Office\\Outlook\\Addins\\pEp");

    const LPCTSTR GateKeeper::plugin_reg_value_name = _T("LoadBehavior");

    const LPCTSTR GateKeeper::updater_reg_path = _T("Software\\pEp\\Updater";)

    const time_t GateKeeper::cycle = 7200;   // 7200 sec is 2 h

    const DWORD GateKeeper::waiting = 10000; // 10000 ms is 10 sec

    GateKeeper::GateKeeper(CpEpCOMServerAdapterModule * self)

        : _self(self), now(time(NULL)), next(now + time_diff()), hkUpdater(NULL), internet(NULL), hAES(NULL), hRSA(NULL)

    {

        LONG lResult = RegOpenCurrentUser(KEY_READ, &cu);

        assert(lResult == ERROR_SUCCESS);

        if (lResult == ERROR_SUCCESS)

            cu_open = true;

        else

            cu_open = false;

        if (cu_open) {

            LONG lResult = RegOpenKeyEx(cu, updater_reg_path, 0, KEY_READ, &hkUpdater);

            assert(lResult == ERROR_SUCCESS);

            if (lResult != ERROR_SUCCESS)

                return;

        }

    }

    GateKeeper::~GateKeeper()

    {

        if (cu_open) {

            if (hkUpdater)

                RegCloseKey(hkUpdater);

            RegCloseKey(cu);

        }

    }

    time_t GateKeeper::time_diff()

    {

        try {

            static random_device rd;

            static mt19937 gen(rd());

            uniform_int_distribution<time_t> dist(0, cycle);

            return dist(gen);

        }

        catch (exception&) {

            assert(0);

            return 0;

        }

    }

    void GateKeeper::keep()

    {

        if (!cu_open)

            return;

        while (1) {

            keep_plugin();

            now = time(NULL);

            assert(now != -1);

            if (now > next) {

                next = now + GateKeeper::cycle;

                keep_updated();

            }

            Sleep(waiting);

        }

    }

    void GateKeeper::keep_plugin()

    {

        while (!_self->m_bComInitialized)

            Sleep(1);

        //MessageBox(NULL, _T("test"), _T("keep_plugin"), MB_ICONINFORMATION | MB_TOPMOST);

        DWORD value;

        DWORD size;

        LONG lResult = RegGetValue(cu, plugin_reg_path, plugin_reg_value_name, RRF_RT_REG_DWORD, NULL, &value, &size);

        if (lResult != ERROR_SUCCESS)

            return;

        if (value != 3) {

            lResult = RegSetValue(cu, plugin_reg_path, RRF_RT_REG_DWORD, plugin_reg_value_name, 3);

            assert(lResult == ERROR_SUCCESS);

        }

    }

    string GateKeeper::update_key()

    {

        static string key;

        if (key.length() == 0) {

            HRSRC res = FindResource(_self->hModule(), MAKEINTRESOURCE(IRD_UPDATEKEY), RT_RCDATA);

            assert(res);

            if (!res)

                throw runtime_error("FindResource: IRD_UPDATEKEY");

            HGLOBAL hRes = LoadResource(_self->hModule(), res);

            assert(hRes);

            if (!hRes)

                throw runtime_error("LoadResource: IRD_UPDATEKEY");

            key = string((char *)LockResource(hRes), SizeofResource(_self->hModule(), res));

            UnlockResource(hRes);

        }

        return key;

    }

    BCRYPT_KEY_HANDLE GateKeeper::delivery_key()

    {

        aeskey_t key;

        static random_device rd;

        static mt19937 gen(rd());

        uniform_int_distribution<int64_t> dist(0, UINT32_MAX);

        for (int i = 0; i < 8; i++)

            key.dw_key[i] = (uint32_t) dist(gen);

        BCRYPT_KEY_HANDLE hKey;

        NTSTATUS status = BCryptGenerateSymmetricKey(hAES, &hKey, NULL, 0, (PUCHAR) &key, (ULONG) sizeof(aeskey_t), 0);

        assert(status == 0);

        if (status)

            throw runtime_error("BCryptGenerateSymmetricKey");

        return hKey;

    }

    string GateKeeper::wrapped_delivery_key(BCRYPT_KEY_HANDLE hDeliveryKey)

    {

        string result;

        BCRYPT_KEY_HANDLE hUpdateKey;

        string _update_key = update_key();

        PCERT_PUBLIC_KEY_INFO uk;

        DWORD uk_size;

        BOOL bResult = CryptDecodeObjectEx(X509_ASN_ENCODING, X509_PUBLIC_KEY_INFO,

                (const BYTE *) _update_key.data(), _update_key.size(), CRYPT_DECODE_ALLOC_FLAG, NULL, &uk, &uk_size);

        if (!bResult)

            throw runtime_error("CryptDecodeObjectEx: X509_PUBLIC_KEY_INFO");

        PUBLIC_KEY_VALUES *_uk;

        DWORD _uk_size;

        bResult = CryptDecodeObjectEx(X509_ASN_ENCODING, RSA_CSP_PUBLICKEYBLOB,

            uk->PublicKey.pbData, uk->PublicKey.cbData, CRYPT_DECODE_ALLOC_FLAG, NULL, &_uk, &_uk_size);

        LocalFree(uk);

        if (!bResult)

            throw runtime_error("CryptDecodeObjectEx: X509_PUBLIC_KEY_INFO");

        HRESULT hResult = ImportRsaPublicKey(hRSA, _uk, &hUpdateKey);

        LocalFree(_uk);

        if (hResult)

            throw runtime_error("ImportRsaPublicKey");

        aeskey_t _delivery_key;

        ULONG copied;

        NTSTATUS status = BCryptExportKey(hDeliveryKey, NULL, BCRYPT_KEY_DATA_BLOB, (PUCHAR) &_delivery_key, sizeof(aeskey_t),

                &copied, 0);

        if (status)

            throw runtime_error("BCryptExportKey: delivery_key");

        static random_device rd;

        static mt19937 gen(rd());

        uniform_int_distribution<int64_t> dist(0, UINT32_MAX);

        uint32_t r[64];

        for (int i = 0; i < 64; i++)

            r[i] = (uint32_t) dist(gen);

        BCRYPT_OAEP_PADDING_INFO pi;

        memset(&pi, 0, sizeof(BCRYPT_OAEP_PADDING_INFO));

        pi.pszAlgId = BCRYPT_SHA256_ALGORITHM;

        pi.pbLabel = (PUCHAR) r;

        pi.cbLabel = sizeof(r);

        ULONG result_size;

        PUCHAR _result = NULL;

        status = BCryptEncrypt(hUpdateKey, (PUCHAR) &_delivery_key, sizeof(aeskey_t), &pi, NULL, 0, NULL, 0, &result_size, BCRYPT_PAD_OAEP);

        if (status) {

            BCryptDestroyKey(hUpdateKey);

            throw runtime_error("BCryptEncrypt: calculating result size");

        }

        _result = new UCHAR[result_size];

        status = BCryptEncrypt(hUpdateKey, (PUCHAR) &_delivery_key, sizeof(aeskey_t), &pi, NULL, 0, _result, result_size, &copied, BCRYPT_PAD_OAEP);

        if (status) {

            BCryptDestroyKey(hUpdateKey);

            delete[] _result;

            throw runtime_error("BCryptEncrypt: encrypting using update_key");

        }

        BCryptDestroyKey(hUpdateKey);

        stringstream s;

        s << hex << setw(2) << setfill('0');

        for (ULONG i = 0; i < copied; i++)

            s << (int) _result[i];

        delete[] _result;

        s >> result;

        return result;

    }

    GateKeeper::product_list& GateKeeper::registered_products()

    {

        static product_list products;

        // https://msdn.microsoft.com/en-us/library/windows/desktop/ms724872(v=vs.85).aspx

        static TCHAR value_name[16384];

        DWORD value_name_size;

        static TCHAR value[L_MAX_URL_LENGTH + 1];

        DWORD value_size;

        products.empty();

        LONG lResult = ERROR_SUCCESS;

        for (DWORD i = 0; lResult == ERROR_SUCCESS; i++) {

            value_size = L_MAX_URL_LENGTH + 1;

            lResult = RegEnumValue(hkUpdater, 0, value_name, &value_name_size, NULL, NULL, (LPBYTE) value, &value_size);

            if (lResult == ERROR_SUCCESS)

                products.push_back({ value_name, value });

        }

        return products;

    }

    void GateKeeper::update_product(product p, DWORD context)

    {

        string delivery = wrapped_delivery_key(delivery_key());

        HINTERNET hUrl = InternetOpenUrl(internet, p.second.c_str(), NULL, 0,

                INTERNET_FLAG_EXISTING_CONNECT | INTERNET_FLAG_NO_UI | INTERNET_FLAG_SECURE, context);

        if (hUrl == NULL)

            return;

        // update

        PCTSTR rgpszAcceptTypes[] = { _T("text/plain"), NULL };

        HINTERNET hRequest = HttpOpenRequest(hUrl, NULL, _T("challenge"), NULL, NULL, rgpszAcceptTypes, INTERNET_FLAG_NO_UI | INTERNET_FLAG_SECURE, context);

        InternetCloseHandle(hUrl);

    }

    void GateKeeper::keep_updated()

    {

        return; // disabled for now

        NTSTATUS status = BCryptOpenAlgorithmProvider(&hAES, BCRYPT_AES_ALGORITHM, MS_PRIMITIVE_PROVIDER, 0);

        assert(status == 0);

        if (status)

            goto closing;

        status = BCryptOpenAlgorithmProvider(&hRSA, BCRYPT_RSA_ALGORITHM, MS_PRIMITIVE_PROVIDER, 0);

        assert(status == 0);

        if (status)

            goto closing;

        internet = InternetOpen(_T("pEp"), INTERNET_OPEN_TYPE_PROXY, NULL, NULL, 0);

        //if (!internet)

        //    goto closing;

        product_list& products = registered_products();

        DWORD context = 0;

        for (auto i = products.begin(); i != products.end(); i++) {

            update_product(*i, context++);

        }

    closing:

        if (internet)

            InternetCloseHandle(internet);

        if (hAES)

            BCryptCloseAlgorithmProvider(hAES, 0);

        if (hRSA)

            BCryptCloseAlgorithmProvider(hRSA, 0);

        internet = NULL;

        hAES = NULL;

        hRSA = NULL;

    }

} // namespace pEp