#include "stdafx.h"

 #include "GateKeeper.h"

 #include "pEpCOMServerAdapter.h"

 using namespace std;

 // from https://msdn.microsoft.com/en-us/library/windows/desktop/dd388945(v=vs.85).aspx

 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 time_t GateKeeper::fraction = 10;  // first update is at 10% of cycle

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

     GateKeeper::GateKeeper(CpEpCOMServerAdapterModule * self)

         : _self(self), now(time(NULL)), next(now /*+ time_diff()*/), hkUpdater(NULL),

         internet(NULL), hAES(NULL), hRSA(NULL)

     {

         if (the_gatekeeper)

             throw runtime_error("second instance of GateKeeper was initialized");

         DeleteFile(get_lockFile().c_str());

         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);

             if (lResult != ERROR_SUCCESS)

                 RegCreateKeyEx(cu, updater_reg_path, 0, NULL, REG_OPTION_NON_VOLATILE, KEY_READ, NULL, &hkUpdater, NULL);

         }

         the_gatekeeper = this;

     }

     GateKeeper::~GateKeeper()

     {

         the_gatekeeper = nullptr;

         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 / fraction);

             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;

                 if (update_enabled())

                     update_now();

             }

             Sleep(waiting);

         }

     }

     void GateKeeper::keep_plugin()

     {

         HKEY hkPluginStart = NULL;

         LONG lResult = RegOpenKeyEx(cu, plugin_reg_path, 0, KEY_WRITE, &hkPluginStart);

         if (lResult != ERROR_SUCCESS)

             return;

         DWORD v = 3;

         lResult = RegSetValueEx(hkPluginStart, plugin_reg_value_name, 0, REG_DWORD, (const BYTE *)&v, sizeof(DWORD));

         assert(lResult == ERROR_SUCCESS);

         RegCloseKey(hkPluginStart);

     }

     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");

 #ifndef NDEBUG

         DWORD keylength = 0;

         ULONG copied = 0;

         status = BCryptGetProperty(hKey, BCRYPT_KEY_LENGTH, (PUCHAR)&keylength, sizeof(DWORD), &copied, 0);

         assert(keylength == 256);

 #endif

         return hKey;

     }

     string GateKeeper::wrapped_delivery_key(BCRYPT_KEY_HANDLE hDeliveryKey)

     {

         string result;

         BCRYPT_KEY_HANDLE hUpdateKey = NULL;

         string _update_key = update_key();

         PCERT_PUBLIC_KEY_INFO uk = NULL;

         DWORD uk_size = 0;

         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 = NULL;

         DWORD _uk_size = 0;

         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 (!hUpdateKey)

             throw runtime_error("ImportRsaPublicKey");

         ULONG psize;

         NTSTATUS status = BCryptGetProperty(hUpdateKey, BCRYPT_ALGORITHM_NAME, NULL, 0, &psize, 0);

         char *prop = new char[psize];

         TCHAR *_prop = (TCHAR *)prop;

         status = BCryptGetProperty(hUpdateKey, BCRYPT_ALGORITHM_NAME, (PUCHAR)prop, psize, &psize, 0);

         if (status)

             throw runtime_error("BCryptGetProperty: BCRYPT_ALGORITHM_NAME");

         ULONG export_size;

         status = BCryptExportKey(hDeliveryKey, NULL, BCRYPT_KEY_DATA_BLOB, NULL, NULL,

             &export_size, 0);

         if (status)

             throw runtime_error("BCryptExportKey: measuring export size");

         PUCHAR _delivery_key = new UCHAR[export_size];

         ULONG copied;

         status = BCryptExportKey(hDeliveryKey, NULL, BCRYPT_KEY_DATA_BLOB, _delivery_key, export_size,

             &copied, 0);

         if (status) {

             delete[] _delivery_key;

             throw runtime_error("BCryptExportKey: delivery_key");

         }

         BCRYPT_OAEP_PADDING_INFO pi;

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

         pi.pszAlgId = BCRYPT_SHA256_ALGORITHM;

         ULONG result_size = 0;

         PUCHAR _result = NULL;

         ULONG blob_size = export_size - sizeof(BCRYPT_KEY_DATA_BLOB_HEADER);

         PUCHAR blob = _delivery_key + sizeof(BCRYPT_KEY_DATA_BLOB_HEADER);

         status = BCryptEncrypt(hUpdateKey, blob, blob_size, &pi, NULL, 0, NULL, 0, &result_size, BCRYPT_PAD_OAEP);

         if (status) {

             delete[] _delivery_key;

             BCryptDestroyKey(hUpdateKey);

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

         }

         _result = new UCHAR[result_size + 1];

         status = BCryptEncrypt(hUpdateKey, blob, blob_size, &pi, NULL, 0, _result, result_size, &copied, BCRYPT_PAD_OAEP);

         delete[] _delivery_key;

         if (status) {

             BCryptDestroyKey(hUpdateKey);

             delete[] _result;

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

         }

         BCryptDestroyKey(hUpdateKey);

         stringstream s;

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

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

             s << (int)_result[i];

         }

         delete[] _result;

         s >> result;

         return result;

     }

     void GateKeeper::enable_update()

     {

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

         if (lResult != ERROR_SUCCESS)

             return;

         lResult = RegSetValueExW(hkUpdater, NULL, 0, REG_SZ, (const BYTE *) _T("1"), sizeof(TCHAR)*2);

     }

     void GateKeeper::disable_update()

     {

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

         if (lResult != ERROR_SUCCESS)

             return;

         lResult = RegSetValueEx(hkUpdater, NULL, 0, REG_SZ, (const BYTE *) _T("0"), sizeof(TCHAR) * 2);

     }

     bool GateKeeper::update_enabled()

     {

         bool enabled = true;

         DWORD esize;

         RegGetValue(cu, updater_reg_path, NULL, RRF_RT_REG_SZ, NULL, NULL, &esize);

         if (esize) {

             TCHAR* edata = new TCHAR[esize];

             RegGetValue(cu, updater_reg_path, NULL, RRF_RT_REG_SZ, NULL, edata, &esize);

             if (tstring(edata) == _T("0"))

                 enabled = false;

             delete[] edata;

         }

         return enabled;

     }

     GateKeeper::product_list GateKeeper::registered_products()

     {

         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;

         LONG lResult = ERROR_SUCCESS;

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

             value_name_size = 16383;

             value_size = L_MAX_URL_LENGTH + 1;

             lResult = RegEnumValue(hkUpdater, i, 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::execute_file(tstring filename)

     {

         HANDLE hMutex = CreateMutex(NULL, TRUE, _T("PEPINSTALLERMUTEX"));

         if (hMutex) {

             CloseHandle(hMutex);

             ShellExecute(NULL, _T("open"), filename.c_str(), NULL, NULL, SW_SHOW);

         }

     }

     tstring GateKeeper::get_lockFile()

     {

         static const tstring _fileName = _T("\\pEpSetup.lck");

         static tstring fileName;

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

             unique_ptr < TCHAR[] > _pathName(new TCHAR[MAX_PATH + 1]);

             DWORD size = GetTempPath(MAX_PATH, _pathName.get());

             if (size > MAX_PATH - _fileName.size())

                 throw runtime_error("TEMP path too long");

             fileName = _pathName.get();

             fileName += _fileName;

         }

         return fileName;

     }

     // Retrieving Headers Using HTTP_QUERY_CUSTOM

     static tstring httpQueryCustom(HINTERNET hHttp, tstring header)

     {

         DWORD dwResult = 0;

         LPTSTR lpOutBuffer = StrDup(header.c_str());

     retry:

         if (!HttpQueryInfo(hHttp, HTTP_QUERY_CUSTOM, (LPVOID)lpOutBuffer, &dwResult, NULL))

         {

             if (GetLastError() == ERROR_HTTP_HEADER_NOT_FOUND)

             {

                 // Code to handle the case where the header isn't available.

                 LocalFree(lpOutBuffer);

                 throw(runtime_error("ERROR_HTTP_HEADER_NOT_FOUND"));

             }

             else

             {

                 // Check for an insufficient buffer.

                 if (GetLastError() == ERROR_INSUFFICIENT_BUFFER)

                 {

                     // Allocate the necessary buffer.

                     LocalFree(lpOutBuffer);

                     lpOutBuffer = (LPTSTR)LocalAlloc(LMEM_FIXED, dwResult + 1);

                     // Rewrite the header name in the buffer.

                     StringCchPrintf(lpOutBuffer, dwResult, header.c_str());

                     // Retry the call.

                     goto retry;

                 }

                 else

                 {

                     // Error handling code.

                     LocalFree(lpOutBuffer);

                     // FIXME: Add GetLastError()

                     throw(runtime_error("Unknown"));

                 }

             }

         }

         tstring result(lpOutBuffer);

         LocalFree(lpOutBuffer);

         return result;

     }

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

     {

         {

             HANDLE file = CreateFile(get_lockFile().c_str(), GENERIC_READ | GENERIC_WRITE, 0, NULL, CREATE_NEW, FILE_ATTRIBUTE_NORMAL, NULL);

             if (file == INVALID_HANDLE_VALUE) {

                 return false;

             }

             else {

                 CloseHandle(file);

                 DeleteFile(get_lockFile().c_str());

             }

         }

         BCRYPT_KEY_HANDLE dk = delivery_key();

 #ifdef UNICODE

         tstring delivery = utility::utf16_string(wrapped_delivery_key(dk));

 #else

         tstring delivery = wrapped_delivery_key(delivery_key());

 #endif

         tstring url = p.second;

         url += _T("&challenge=");

         url += delivery;

         tstring headers;

         HINTERNET hUrl = InternetOpenUrl(internet, url.c_str(), headers.c_str(), headers.length(),

             INTERNET_FLAG_EXISTING_CONNECT | INTERNET_FLAG_NO_UI | INTERNET_FLAG_SECURE, context);

         if (hUrl == NULL)

             return false;

         string crypted;

         string unencrypted;

         UCHAR iv[12];

         UCHAR nonce[sizeof(iv)];

         UCHAR tag[16];

         tstring filename;

         HANDLE hFile = NULL;

         char *unencrypted_buffer = NULL;

         bool result = false;

         try {

             DWORD reading;

             InternetReadFile(hUrl, iv, sizeof(iv), &reading);

             if (reading) do {

                 static char buffer[1024 * 1024];

                 BOOL bResult = InternetReadFile(hUrl, buffer, 1024 * 1024, &reading);

                 if (!bResult || !reading)

                     break;

                 crypted += string(buffer, reading);

             } while (1);

             tstring contentDisposition = httpQueryCustom(hUrl, _T("Content-Disposition"));

             tregex filenameRegex(_T("filename=.([^\"]*)"), regex::extended); //FIXME: case insensitive

             tsmatch match;

             if (regex_search(contentDisposition, match, filenameRegex)) {

                 filename = match[1];

             }

             InternetCloseHandle(hUrl);

             hUrl = NULL;

             memcpy(nonce, iv, sizeof(iv));

             BCRYPT_AUTHENTICATED_CIPHER_MODE_INFO authInfo;

             BCRYPT_INIT_AUTH_MODE_INFO(authInfo);

             authInfo.pbNonce = nonce;

             authInfo.cbNonce = sizeof(nonce);

             authInfo.pbTag = tag;

             authInfo.cbTag = sizeof(tag);

             ULONG unencrypted_size;

             NTSTATUS status = BCryptDecrypt(dk, (PUCHAR)crypted.data(), crypted.size(),

                 &authInfo, iv, sizeof(iv), NULL, 0, &unencrypted_size, 0);

             if (status)

                 goto closing;

             unencrypted_buffer = new char[unencrypted_size];

             PUCHAR crypted_data = (PUCHAR)crypted.data();

             ULONG crypted_size = (ULONG)crypted.size() - sizeof(tag);

             memcpy(tag, crypted_data + crypted_size, sizeof(tag));

             status = BCryptDecrypt(dk, crypted_data, crypted_size,

                 &authInfo, iv, sizeof(iv), (PUCHAR)unencrypted_buffer, unencrypted_size, &unencrypted_size, 0);

             if (status)

                 goto closing;

             BCryptDestroyKey(dk);

             TCHAR download_path[MAX_PATH + 1];

             PWSTR _downloads;

             SHGetKnownFolderPath(FOLDERID_Downloads, 0, NULL, &_downloads);

             StringCchCopy(download_path, MAX_PATH, _downloads);

             CoTaskMemFree(_downloads);

             GetTempPath(MAX_PATH, download_path);

             if (filename == _T("")) {

                 filename = download_path;

                 filename += _T("\\pEp_");

                 filename += delivery.substr(0, 32);

                 filename += _T(".msi");

             }

             else {

                 filename = tstring(download_path) + _T("\\") + filename;

             }

             hFile = CreateFile(filename.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

             if (!hFile)

                 goto closing;

             DWORD writing;

             WriteFile(hFile, unencrypted_buffer, unencrypted_size, &writing, NULL);

             CloseHandle(hFile);

             hFile = NULL;

             delete[] unencrypted_buffer;

             unencrypted_buffer = nullptr;

         }

         catch (exception&) {

             goto closing;

         }

         execute_file(filename);

         result = true;

     closing:

         if (unencrypted_buffer)

             delete[] unencrypted_buffer;

         if (hFile)

             CloseHandle(hFile);

         if (hUrl)

             InternetCloseHandle(hUrl);

         BCryptDestroyKey(dk);

         return result;

     }

     void GateKeeper::update_now()

     {

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

         assert(status == 0);

         if (status)

             goto closing;

         status = BCryptSetProperty(hAES, BCRYPT_CHAINING_MODE, (PUCHAR)BCRYPT_CHAIN_MODE_GCM, sizeof(BCRYPT_CHAIN_MODE_GCM), 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_PRECONFIG, NULL, NULL, 0);

         if (!internet)

             goto closing;

         {

             product_list products = registered_products();

             DWORD context = 0;

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

                 try {

                     update_product(*i, context++);

                 }

                 catch (exception&) {

                 }

             }

         }

     closing:

         if (internet)

             InternetCloseHandle(internet);

         if (hAES)

             BCryptCloseAlgorithmProvider(hAES, 0);

         if (hRSA)

             BCryptCloseAlgorithmProvider(hRSA, 0);

         internet = NULL;

         hAES = NULL;

         hRSA = NULL;

     }

     GateKeeper *GateKeeper::the_gatekeeper = nullptr;

 } // namespace pEp