Merge branch 'b11.16' into 'master'11.16

add upstream 11.16

See merge request opensource-tracking/FreeFileSync!40

12 files changed, 718 insertions, 678 deletions

diff --git a/zen/file_access.cpp b/zen/file_access.cpp
index 6940b22f..2fbcf803 100644
--- a/zen/file_access.cpp
+++ b/zen/file_access.cpp
@@ -17,7 +17,7 @@
 #include "guid.h"
 
     #include <sys/vfs.h> //statfs
-    #include <sys/time.h> //lutimes
+    //#include <sys/time.h> //lutimes
     #ifdef HAVE_SELINUX
         #include <selinux/selinux.h>
     #endif
@@ -309,42 +309,51 @@ namespace
 {
 void setWriteTimeNative(const Zstring& itemPath, const timespec& modTime, ProcSymlink procSl) //throw FileError
 {
-    /*
-    [2013-05-01] sigh, we can't use utimensat() on NTFS volumes on Ubuntu: silent failure!!! what morons are programming this shit???
-    => fallback to "retarded-idiot version"! -- DarkByte
-
-    [2015-03-09]
-     - cannot reproduce issues with NTFS and utimensat() on Ubuntu
-     - utimensat() is supposed to obsolete utime/utimes and is also used by "cp" and "touch"
-        => let's give utimensat another chance:
-        using open()/futimens() for regular files and utimensat(AT_SYMLINK_NOFOLLOW) for symlinks is consistent with "cp" and "touch"!
-    */
+    /* [2013-05-01] sigh, we can't use utimensat() on NTFS volumes on Ubuntu: silent failure!!! what morons are programming this shit???
+        => fallback to "retarded-idiot version"! -- DarkByte
+
+        [2015-03-09]
+         - cannot reproduce issues with NTFS and utimensat() on Ubuntu
+         - utimensat() is supposed to obsolete utime/utimes and is also used by "cp" and "touch"
+            => let's give utimensat another chance:
+            using open()/futimens() for regular files and utimensat(AT_SYMLINK_NOFOLLOW) for symlinks is consistent with "cp" and "touch"!
+        cp:    https://github.com/coreutils/coreutils/blob/master/src/cp.c
+            => utimens: https://github.com/coreutils/gnulib/blob/master/lib/utimens.c
+        touch: https://github.com/coreutils/coreutils/blob/master/src/touch.c
+            => fdutimensat: https://github.com/coreutils/gnulib/blob/master/lib/fdutimensat.c                  */
     timespec newTimes[2] = {};
-    newTimes[0].tv_sec = ::time(nullptr); //access time; using UTIME_OMIT for tv_nsec would trigger even more bugs: https://freefilesync.org/forum/viewtopic.php?t=1701
+    newTimes[0].tv_sec = ::time(nullptr); //access time; don't use UTIME_NOW/UTIME_OMIT: more bugs! https://freefilesync.org/forum/viewtopic.php?t=1701
     newTimes[1] = modTime; //modification time
     //test: even modTime == 0 is correctly applied (no NOOP!) test2: same behavior for "utime()"
 
-    if (procSl == ProcSymlink::follow)
+    //hell knows why files on gvfs-mounted Samba shares fail to open(O_WRONLY) returning EOPNOTSUPP:
+    //https://freefilesync.org/forum/viewtopic.php?t=2803 => utimensat() works (but not for gvfs SFTP)
+    if (::utimensat(AT_FDCWD, itemPath.c_str(), newTimes, procSl == ProcSymlink::direct ? AT_SYMLINK_NOFOLLOW : 0) == 0)
+        return;
+    try
     {
-        //hell knows why files on gvfs-mounted Samba shares fail to open(O_WRONLY) returning EOPNOTSUPP:
-        //https://freefilesync.org/forum/viewtopic.php?t=2803 => utimensat() works (but not for gvfs SFTP)
-        if (::utimensat(AT_FDCWD, itemPath.c_str(), newTimes, 0) == 0)
-            return;
+        if (procSl == ProcSymlink::direct)
+            try
+            {
+                if (getItemType(itemPath) == ItemType::symlink) //throw FileError
+                    THROW_LAST_SYS_ERROR("utimensat(AT_SYMLINK_NOFOLLOW)"); //use lutimes()? just a wrapper around utimensat()!
+                //else: fall back
+            }
+            catch (const FileError& e) { throw SysError(e.toString()); }
 
         //in other cases utimensat() returns EINVAL for CIFS/NTFS drives, but open+futimens works: https://freefilesync.org/forum/viewtopic.php?t=387
-        const int fdFile = ::open(itemPath.c_str(), O_WRONLY | O_APPEND | O_CLOEXEC); //2017-07-04: O_WRONLY | O_APPEND seems to avoid EOPNOTSUPP on gvfs SFTP!
+        //2017-07-04: O_WRONLY | O_APPEND seems to avoid EOPNOTSUPP on gvfs SFTP!
+        const int fdFile = ::open(itemPath.c_str(), O_WRONLY | O_APPEND | O_CLOEXEC);
         if (fdFile == -1)
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot write modification time of %x."), L"%x", fmtPath(itemPath)), "open");
+            THROW_LAST_SYS_ERROR("open");
         ZEN_ON_SCOPE_EXIT(::close(fdFile));
 
         if (::futimens(fdFile, newTimes) != 0)
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot write modification time of %x."), L"%x", fmtPath(itemPath)), "futimens");
-    }
-    else
-    {
-        if (::utimensat(AT_FDCWD, itemPath.c_str(), newTimes, AT_SYMLINK_NOFOLLOW) != 0)
-            THROW_LAST_FILE_ERROR(replaceCpy(_("Cannot write modification time of %x."), L"%x", fmtPath(itemPath)), "utimensat");
+            THROW_LAST_SYS_ERROR("futimens");
+
+        //need  more fallbacks? e.g. futimes()? careful, bugs! futimes() rounds instead of truncates when falling back on utime()!
     }
+    catch (const SysError& e) { throw FileError(replaceCpy(_("Cannot write modification time of %x."), L"%x", fmtPath(itemPath)), e.toString()); }
 }
 
 
diff --git a/zen/http.cpp b/zen/http.cpp
index 05ed81d1..fe3b8c4c 100644
--- a/zen/http.cpp
+++ b/zen/http.cpp
@@ -5,11 +5,15 @@
 // *****************************************************************************
 
 #include "http.h"
-    #include "socket.h"
-    #include "open_ssl.h"
+
+    #include <libcurl/curl_wrap.h> //DON'T include <curl/curl.h> directly!
+    #include "stream_buffer.h"
+    #include "thread.h"
 
 using namespace zen;
 
+const std::chrono::seconds HTTP_ACCESS_TIME_OUT(20);
+
 
 
 
@@ -17,15 +21,15 @@ class HttpInputStream::Impl
 {
 public:
     Impl(const Zstring& url,
-         const std::string* postBuf /*issue POST if bound, GET otherwise*/,
+         const std::string* postBuf, //issue POST if bound, GET otherwise
          const std::string& contentType, //required for POST
-         bool disableGetCache /*not relevant for POST (= never cached)*/,
+         bool disableGetCache, //not relevant for POST (= never cached)
          const Zstring& userAgent,
-         const Zstring* caCertFilePath /*optional: enable certificate validation*/,
-         const IoCallback& notifyUnbufferedIO) : //throw SysError, X
+         const Zstring& caCertFilePath, //optional: enable certificate validation
+         const IoCallback& notifyUnbufferedIO /*throw X*/) : //throw SysError, X
         notifyUnbufferedIO_(notifyUnbufferedIO)
     {
-        ZEN_ON_SCOPE_FAIL(cleanup(); /*destructor call would lead to member double clean-up!!!*/);
+        ZEN_ON_SCOPE_FAIL(cleanup()); //destructor call would lead to member double clean-up!!!
 
         //may be sending large POST: call back first
         if (notifyUnbufferedIO_) notifyUnbufferedIO_(0); //throw X
@@ -43,76 +47,95 @@ public:
             throw SysError(L"URL uses unexpected protocol.");
         }();
 
-        assert(postBuf || contentType.empty());
-
         std::map<std::string, std::string, LessAsciiNoCase> headers;
 
+        assert(postBuf || contentType.empty());
         if (postBuf && !contentType.empty())
             headers["Content-Type"] = contentType;
 
-        if (useTls) //HTTP default port: 443, see %WINDIR%\system32\drivers\etc\services
-        {
-            socket_ = std::make_unique<Socket>(server, Zstr("https")); //throw SysError
-            tlsCtx_ = std::make_unique<TlsContext>(socket_->get(), server, caCertFilePath); //throw SysError
-        }
-        else //HTTP default port: 80, see %WINDIR%\system32\drivers\etc\services
-            socket_ = std::make_unique<Socket>(server, Zstr("http")); //throw SysError
-
-        //we don't support "chunked and gzip transfer encoding" => HTTP 1.0 => no "Content-Length" support!
-        headers["Host"      ] = utfTo<std::string>(server); //only required for HTTP/1.1 but a few servers expect it even for HTTP/1.0
-        headers["User-Agent"] = utfTo<std::string>(userAgent);
-        headers["Accept"    ] = "*/*"; //won't hurt?
-
-        if (!postBuf /*HTTP GET*/ && disableGetCache)
-            headers["Pragma"] = "no-cache"; //HTTP 1.0 only! superseeded by "Cache-Control"
-
-        if (postBuf)
-            headers["Content-Length"] = numberTo<std::string>(postBuf->size());
-
-        //https://www.w3.org/Protocols/HTTP/1.0/spec.html#Request-Line
-        std::string msg = (postBuf ? "POST " : "GET ") + utfTo<std::string>(page) + " HTTP/1.0\r\n";
-        for (const auto& [name, value] : headers)
-            msg += name + ": " + value + "\r\n";
-        msg += "\r\n";
-        if (postBuf)
-            msg += *postBuf;
-
-        //send request
-        for (size_t bytesToSend = msg.size(); bytesToSend > 0;)
-            bytesToSend -= tlsCtx_ ?
-                           tlsCtx_->tryWrite(             &*(msg.end() - bytesToSend), bytesToSend) : //throw SysError
-                           tryWriteSocket(socket_->get(), &*(msg.end() - bytesToSend), bytesToSend);  //throw SysError
-
-        //shutdownSocketSend(socket_->get()); //throw SysError
-        //NO! Sending TCP FIN before receiving response (aka "TCP Half Closed") is not always supported! e.g. Cloudflare server will immediately end connection: recv() returns 0.
-        //"clients SHOULD NOT half-close their TCP connections": https://github.com/httpwg/http-core/issues/22
-
-        //receive response:
-        std::string headBuf;
-        const std::string headerDelim = "\r\n\r\n";
-        for (std::string buf;;)
+        if (!postBuf /*=> HTTP GET*/ && disableGetCache) //libcurl doesn't cache internally, so it should be enough to set this header
+            headers["Cache-Control"] = "no-cache"; //= similar to WinInet's INTERNET_FLAG_RELOAD
+        //caveat: INTERNET_FLAG_RELOAD issues "Pragma: no-cache" instead if "request is going through a proxy"
+
+
+        auto promiseHeader = std::make_shared<std::promise<std::string>>();
+        std::future<std::string> futHeader = promiseHeader->get_future();
+
+        worker_ = InterruptibleThread([asyncStreamOut = this->asyncStreamIn_, promiseHeader, headers = std::move(headers),
+                                                      server, useTls, caCertFilePath, userAgent = utfTo<std::string>(userAgent),
+                                                      postBuf = postBuf ? std::optional<std::string>(*postBuf) : std::nullopt, //[!] life-time!
+                                                      serverRelPath = utfTo<std::string>(page)]
         {
-            const size_t blockSize = std::min(static_cast<size_t>(1024), memBuf_.size()); //smaller block size: try to only read header part
-            buf.resize(buf.size() + blockSize);
-            const size_t bytesReceived = tryRead(&*(buf.end() - blockSize), blockSize); //throw SysError
-            buf.resize(buf.size() - (blockSize - bytesReceived)); //caveat: unsigned arithmetics
+            setCurrentThreadName(Zstr("HttpInputStream ") + server);
 
-            if (contains(buf, headerDelim))
+            bool headerReceived = false;
+            try
             {
-                headBuf                   = beforeFirst(buf, headerDelim, IfNotFoundReturn::none);
-                const std::string bodyBuf = afterFirst (buf, headerDelim, IfNotFoundReturn::none);
-                //put excess bytes into instance buffer for body retrieval
-                assert(bufPos_ == 0 && bufPosEnd_ == 0);
-                bufPosEnd_ = bodyBuf.size();
-                std::copy(bodyBuf.begin(), bodyBuf.end(), reinterpret_cast<char*>(&memBuf_[0]));
-                break;
+                std::vector<std::string> curlHeaders;
+                for (const auto& [name, value] : headers)
+                    curlHeaders.push_back(name + ": " + value);
+
+                std::vector<CurlOption> extraOptions {{CURLOPT_USERAGENT, userAgent.c_str()}};
+                //CURLOPT_FOLLOWLOCATION already off by default :)
+                if (postBuf)
+                {
+                    extraOptions.emplace_back(CURLOPT_POSTFIELDS,          postBuf->c_str());
+                    extraOptions.emplace_back(CURLOPT_POSTFIELDSIZE_LARGE, postBuf->size()); //postBuf not necessarily null-terminated!                    
+                }
+
+                //carefully with these callbacks! First receive HTTP header without blocking,
+                //and only then allow AsyncStreamBuffer::write() which can block!
+
+                std::string headerBuf;
+                auto onHeaderData = [&](const std::string_view& headerLine)
+                {
+                    if (headerReceived)
+                        throw SysError(L"Unexpected header data after end of HTTP header.");
+
+                    //"The callback will be called once for each header and only complete header lines are passed on to the callback" (including \r\n at the end)
+                    headerBuf += headerLine;
+
+                    if (headerLine == "\r\n")
+                    {
+                        headerReceived = true;
+                        promiseHeader->set_value(std::move(headerBuf));
+                    }
+                };
+
+                HttpSession httpSession(server, useTls, caCertFilePath, HTTP_ACCESS_TIME_OUT); //throw SysError
+
+                auto writeResponse = [&](std::span<const char> buf)
+                {
+                    if (!headerReceived)
+                        throw SysError(L"Received HTTP body without header.");
+
+                    return asyncStreamOut->write(buf.data(), buf.size()); //throw ThreadStopRequest
+                };
+
+                httpSession.perform(serverRelPath, //throw SysError, ThreadStopRequest
+                                    curlHeaders, extraOptions,
+                                    writeResponse /*throw ThreadStopRequest*/,
+                                    nullptr /*readRequest*/,
+                                    onHeaderData /*throw SysError*/);
+
+                if (!headerReceived)
+                    throw SysError(L"HTTP response is missing header.");
+
+                asyncStreamOut->closeStream();
             }
-            if (bytesReceived == 0)
-                break;
-        }
-        //parse header
-        const std::string statusBuf  = beforeFirst(headBuf, "\r\n", IfNotFoundReturn::all);
-        const std::string headersBuf = afterFirst (headBuf, "\r\n", IfNotFoundReturn::none);
+            catch (SysError&) //let ThreadStopRequest pass through!
+            {
+                if (!headerReceived)
+                    promiseHeader->set_exception(std::current_exception());
+
+                asyncStreamOut->setWriteError(std::current_exception());
+            }
+        });
+
+        const std::string headBuf = futHeader.get(); //throw SysError
+        //parse header: https://www.w3.org/Protocols/HTTP/1.0/spec.html#Request-Line
+        const std::string& statusBuf  = beforeFirst(headBuf, "\r\n", IfNotFoundReturn::all);
+        const std::string& headersBuf = afterFirst (headBuf, "\r\n", IfNotFoundReturn::none);
 
         const std::vector<std::string> statusItems = split(statusBuf, ' ', SplitOnEmpty::allow); //HTTP-Version SP Status-Code SP Reason-Phrase CRLF
         if (statusItems.size() < 2 || !startsWith(statusItems[0], "HTTP/"))
@@ -124,9 +147,9 @@ public:
             responseHeaders_[trimCpy(beforeFirst(line, ':', IfNotFoundReturn::all))] =
                 /**/         trimCpy(afterFirst (line, ':', IfNotFoundReturn::none));
 
-        //try to get "Content-Length" header if available
-        if (const std::string* value = getHeader("Content-Length"))
-            contentRemaining_ = stringTo<int64_t>(*value) - (bufPosEnd_ - bufPos_);
+        /* let's NOT consider "Content-Length" header:
+            - may be unavailable ("Transfer-Encoding: chunked")
+            - may refer to compressed data size ("Content-Encoding: gzip") */
 
         //let's not get too finicky: at least report the logical amount of bytes sent/received (excluding HTTP headers)
         if (notifyUnbufferedIO_) notifyUnbufferedIO_(postBuf ? postBuf->size() : 0); //throw X
@@ -134,7 +157,6 @@ public:
 
     ~Impl() { cleanup(); }
 
-
     const int getStatusCode() const { return statusCode_; }
 
     const std::string* getHeader(const std::string& name) const
@@ -145,79 +167,37 @@ public:
 
     size_t read(void* buffer, size_t bytesToRead) //throw SysError, X; return "bytesToRead" bytes unless end of stream!
     {
-        const size_t blockSize = getBlockSize();
-        assert(memBuf_.size() >= blockSize);
-        assert(bufPos_ <= bufPosEnd_ && bufPosEnd_ <= memBuf_.size());
-
-        auto       it    = static_cast<std::byte*>(buffer);
-        const auto itEnd = it + bytesToRead;
-        for (;;)
-        {
-            const size_t junkSize = std::min(static_cast<size_t>(itEnd - it), bufPosEnd_ - bufPos_);
-            std::memcpy(it, &memBuf_[0] + bufPos_, junkSize);
-            bufPos_ += junkSize;
-            it      += junkSize;
-
-            if (it == itEnd)
-                break;
-            //--------------------------------------------------------------------
-            const size_t bytesRead = tryRead(&memBuf_[0], blockSize); //throw SysError; may return short, only 0 means EOF! => CONTRACT: bytesToRead > 0
-            bufPos_ = 0;
-            bufPosEnd_ = bytesRead;
-
-            if (notifyUnbufferedIO_) notifyUnbufferedIO_(bytesRead); //throw X
-
-            if (bytesRead == 0) //end of file
-                break;
-        }
-        return it - static_cast<std::byte*>(buffer);
+        const size_t bytesRead = asyncStreamIn_->read(buffer, bytesToRead); //throw SysError
+        reportBytesProcessed(); //throw X
+        return bytesRead;
+        //no need for asyncStreamIn_->checkWriteErrors(): once end of stream is reached, asyncStreamOut->closeStream() was called => no errors occured
     }
 
     size_t getBlockSize() const { return 64 * 1024; }
 
 private:
-    size_t tryRead(void* buffer, size_t bytesToRead) //throw SysError; may return short, only 0 means EOF!
-    {
-        assert(bytesToRead <= getBlockSize()); //block size might be 1000 while reading HTTP header
-
-        if (contentRemaining_ >= 0)
-        {
-            if (contentRemaining_ == 0)
-                return 0;
-            bytesToRead = static_cast<size_t>(std::min(static_cast<int64_t>(bytesToRead), contentRemaining_)); //[!] contentRemaining_ > 4 GB possible!
-        }
-        const size_t bytesReceived = tlsCtx_ ?
-                                     tlsCtx_->tryRead(                buffer, bytesToRead) : //throw SysError; may return short, only 0 means EOF!
-                                     tryReadSocket   (socket_->get(), buffer, bytesToRead);  //
-        if (contentRemaining_ >= 0)
-            contentRemaining_ -= bytesReceived;
-
-        if (bytesReceived == 0 && contentRemaining_ > 0)
-            throw SysError(formatSystemError("HttpInputStream::tryRead", L"", L"Incomplete server response: " +
-                                             numberTo<std::wstring>(contentRemaining_) + L" more bytes expected."));
+    Impl           (const Impl&) = delete;
+    Impl& operator=(const Impl&) = delete;
 
-        return bytesReceived; //"zero indicates end of file"
+    void reportBytesProcessed() //throw X
+    {
+        const int64_t totalBytesDownloaded = asyncStreamIn_->getTotalBytesWritten();
+        if (notifyUnbufferedIO_) notifyUnbufferedIO_(totalBytesDownloaded - totalBytesReported_); //throw X
+        totalBytesReported_ = totalBytesDownloaded;
     }
 
     void cleanup()
     {
+        asyncStreamIn_->setReadError(std::make_exception_ptr(ThreadStopRequest()));
     }
 
-    Impl           (const Impl&) = delete;
-    Impl& operator=(const Impl&) = delete;
-
-    std::unique_ptr<Socket> socket_;     //*bound* after constructor has run
-    std::unique_ptr<TlsContext> tlsCtx_; //optional: support HTTPS
+    std::shared_ptr<AsyncStreamBuffer> asyncStreamIn_ = std::make_shared<AsyncStreamBuffer>(512 * 1024);
+    InterruptibleThread worker_;
+    int64_t totalBytesReported_ = 0;
     int statusCode_ = 0;
     std::map<std::string, std::string, LessAsciiNoCase> responseHeaders_;
 
-    int64_t contentRemaining_ = -1; //consider "Content-Length" if available
-
     const IoCallback notifyUnbufferedIO_; //throw X
-
-    std::vector<std::byte> memBuf_ = std::vector<std::byte>(getBlockSize());
-    size_t bufPos_    = 0; //buffered I/O; see file_io.cpp
-    size_t bufPosEnd_ = 0; //
 };
 
 
@@ -238,7 +218,7 @@ std::unique_ptr<HttpInputStream::Impl> sendHttpRequestImpl(const Zstring& url,
                                                            const std::string* postBuf /*issue POST if bound, GET otherwise*/,
                                                            const std::string& contentType, //required for POST
                                                            const Zstring& userAgent,
-                                                           const Zstring* caCertFilePath /*optional: enable certificate validation*/,
+                                                           const Zstring& caCertFilePath /*optional: enable certificate validation*/,
                                                            const IoCallback& notifyUnbufferedIO) //throw SysError, X
 {
     Zstring urlRed = url;
@@ -338,14 +318,14 @@ std::vector<std::pair<std::string, std::string>> zen::xWwwFormUrlDecode(const st
 }
 
 
-HttpInputStream zen::sendHttpGet(const Zstring& url, const Zstring& userAgent, const Zstring* caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
+HttpInputStream zen::sendHttpGet(const Zstring& url, const Zstring& userAgent, const Zstring& caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
 {
     return sendHttpRequestImpl(url, nullptr /*postBuf*/, "" /*contentType*/, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X, X
 }
 
 
 HttpInputStream zen::sendHttpPost(const Zstring& url, const std::vector<std::pair<std::string, std::string>>& postParams,
-                                  const Zstring& userAgent, const Zstring* caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
+                                  const Zstring& userAgent, const Zstring& caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
 {
     return sendHttpPost(url, xWwwFormUrlEncode(postParams), "application/x-www-form-urlencoded", userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
 }
@@ -353,7 +333,7 @@ HttpInputStream zen::sendHttpPost(const Zstring& url, const std::vector<std::pai
 
 
 HttpInputStream zen::sendHttpPost(const Zstring& url, const std::string& postBuf, const std::string& contentType,
-                                  const Zstring& userAgent, const Zstring* caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
+                                  const Zstring& userAgent, const Zstring& caCertFilePath, const IoCallback& notifyUnbufferedIO) //throw SysError, X
 {
     return sendHttpRequestImpl(url, &postBuf, contentType, userAgent, caCertFilePath, notifyUnbufferedIO); //throw SysError, X
 }
@@ -368,7 +348,7 @@ bool zen::internetIsAlive() //noexcept
                                                                 "" /*contentType*/,
                                                                 true /*disableGetCache*/,
                                                                 Zstr("FreeFileSync"),
-                                                                nullptr /*caCertFilePath*/,
+                                                                Zstring() /*caCertFilePath*/,
                                                                 nullptr /*notifyUnbufferedIO*/); //throw SysError
         const int statusCode = response->getStatusCode();
 
@@ -386,72 +366,72 @@ std::wstring zen::formatHttpError(int sc)
     {
         switch (sc)
         {
-			//*INDENT-OFF*
-			case 300: return L"Multiple choices.";
-			case 301: return L"Moved permanently.";
-			case 302: return L"Moved temporarily.";
-			case 303: return L"See other";
-			case 304: return L"Not modified.";
-			case 305: return L"Use proxy.";
-			case 306: return L"Switch proxy.";
-			case 307: return L"Temporary redirect.";
-			case 308: return L"Permanent redirect.";
-
-			case 400: return L"Bad request.";
-			case 401: return L"Unauthorized.";
-			case 402: return L"Payment required.";
-			case 403: return L"Forbidden.";
-			case 404: return L"Not found.";
-			case 405: return L"Method not allowed.";
-			case 406: return L"Not acceptable.";
-			case 407: return L"Proxy authentication required.";
-			case 408: return L"Request timeout.";
-			case 409: return L"Conflict.";
-			case 410: return L"Gone.";
-			case 411: return L"Length required.";
-			case 412: return L"Precondition failed.";
-			case 413: return L"Payload too large.";
-			case 414: return L"URI too long.";
-			case 415: return L"Unsupported media type.";
-			case 416: return L"Range not satisfiable.";
-			case 417: return L"Expectation failed.";
-			case 418: return L"I'm a teapot.";
-			case 421: return L"Misdirected request.";
-			case 422: return L"Unprocessable entity.";
-			case 423: return L"Locked.";
-			case 424: return L"Failed dependency.";
-			case 425: return L"Too early.";
-			case 426: return L"Upgrade required.";
-			case 428: return L"Precondition required.";
-			case 429: return L"Too many requests.";
-			case 431: return L"Request header fields too large.";
-			case 451: return L"Unavailable for legal reasons.";
-
-			case 500: return L"Internal server error.";
-			case 501: return L"Not implemented.";
-			case 502: return L"Bad gateway.";
-			case 503: return L"Service unavailable.";
-			case 504: return L"Gateway timeout.";
-			case 505: return L"HTTP version not supported.";
-			case 506: return L"Variant also negotiates.";
-			case 507: return L"Insufficient storage.";
-			case 508: return L"Loop detected.";
-			case 510: return L"Not extended.";
-			case 511: return L"Network authentication required.";
-
-			//Cloudflare errors regarding origin server:
-			case 520: return L"Unknown error (Cloudflare)";
-			case 521: return L"Web server is down (Cloudflare)";
-			case 522: return L"Connection timed out (Cloudflare)";
-			case 523: return L"Origin is unreachable (Cloudflare)";
-			case 524: return L"A timeout occurred (Cloudflare)";
-			case 525: return L"SSL handshake failed (Cloudflare)";
-			case 526: return L"Invalid SSL certificate (Cloudflare)";
-			case 527: return L"Railgun error (Cloudflare)";
-			case 530: return L"Origin DNS error (Cloudflare)";
-
-			default:  return L"";
-			//*INDENT-ON*
+            //*INDENT-OFF*
+            case 300: return L"Multiple choices.";
+            case 301: return L"Moved permanently.";
+            case 302: return L"Moved temporarily.";
+            case 303: return L"See other";
+            case 304: return L"Not modified.";
+            case 305: return L"Use proxy.";
+            case 306: return L"Switch proxy.";
+            case 307: return L"Temporary redirect.";
+            case 308: return L"Permanent redirect.";
+
+            case 400: return L"Bad request.";
+            case 401: return L"Unauthorized.";
+            case 402: return L"Payment required.";
+            case 403: return L"Forbidden.";
+            case 404: return L"Not found.";
+            case 405: return L"Method not allowed.";
+            case 406: return L"Not acceptable.";
+            case 407: return L"Proxy authentication required.";
+            case 408: return L"Request timeout.";
+            case 409: return L"Conflict.";
+            case 410: return L"Gone.";
+            case 411: return L"Length required.";
+            case 412: return L"Precondition failed.";
+            case 413: return L"Payload too large.";
+            case 414: return L"URI too long.";
+            case 415: return L"Unsupported media type.";
+            case 416: return L"Range not satisfiable.";
+            case 417: return L"Expectation failed.";
+            case 418: return L"I'm a teapot.";
+            case 421: return L"Misdirected request.";
+            case 422: return L"Unprocessable entity.";
+            case 423: return L"Locked.";
+            case 424: return L"Failed dependency.";
+            case 425: return L"Too early.";
+            case 426: return L"Upgrade required.";
+            case 428: return L"Precondition required.";
+            case 429: return L"Too many requests.";
+            case 431: return L"Request header fields too large.";
+            case 451: return L"Unavailable for legal reasons.";
+
+            case 500: return L"Internal server error.";
+            case 501: return L"Not implemented.";
+            case 502: return L"Bad gateway.";
+            case 503: return L"Service unavailable.";
+            case 504: return L"Gateway timeout.";
+            case 505: return L"HTTP version not supported.";
+            case 506: return L"Variant also negotiates.";
+            case 507: return L"Insufficient storage.";
+            case 508: return L"Loop detected.";
+            case 510: return L"Not extended.";
+            case 511: return L"Network authentication required.";
+
+            //Cloudflare errors regarding origin server:
+            case 520: return L"Unknown error (Cloudflare)";
+            case 521: return L"Web server is down (Cloudflare)";
+            case 522: return L"Connection timed out (Cloudflare)";
+            case 523: return L"Origin is unreachable (Cloudflare)";
+            case 524: return L"A timeout occurred (Cloudflare)";
+            case 525: return L"SSL handshake failed (Cloudflare)";
+            case 526: return L"Invalid SSL certificate (Cloudflare)";
+            case 527: return L"Railgun error (Cloudflare)";
+            case 530: return L"Origin DNS error (Cloudflare)";
+
+            default:  return L"";
+            //*INDENT-ON*
         }
     }();
 
diff --git a/zen/http.h b/zen/http.h
index 07c3f28c..9457309c 100644
--- a/zen/http.h
+++ b/zen/http.h
@@ -13,10 +13,8 @@
 
 namespace zen
 {
-/*
-    - thread-safe! (Window/Linux/macOS)
-    - Linux/macOS: init OpenSSL before use!
-*/
+/*  - thread-safe! (Window/Linux/macOS)
+    - Linux/macOS: init libcurl before use!   */
 class HttpInputStream
 {
 public:
@@ -38,19 +36,19 @@ private:
 
 HttpInputStream sendHttpGet(const Zstring& url,
                             const Zstring& userAgent,
-                            const Zstring* caCertFilePath /*optional: enable certificate validation*/,
+                            const Zstring& caCertFilePath /*optional: enable certificate validation*/,
                             const IoCallback& notifyUnbufferedIO /*throw X*/); //throw SysError, X
 
 HttpInputStream sendHttpPost(const Zstring& url,
                              const std::vector<std::pair<std::string, std::string>>& postParams,
                              const Zstring& userAgent,
-                             const Zstring* caCertFilePath /*optional: enable certificate validation*/,
+                             const Zstring& caCertFilePath /*optional: enable certificate validation*/,
                              const IoCallback& notifyUnbufferedIO /*throw X*/); //throw SysError, X
 
 HttpInputStream sendHttpPost(const Zstring& url,
                              const std::string& postBuf, const std::string& contentType,
                              const Zstring& userAgent,
-                             const Zstring* caCertFilePath /*optional: enable certificate validation*/,
+                             const Zstring& caCertFilePath /*optional: enable certificate validation*/,
                              const IoCallback& notifyUnbufferedIO /*throw X*/); //throw SysError, X
 
 bool internetIsAlive(); //noexcept
diff --git a/zen/open_ssl.cpp b/zen/open_ssl.cpp
index e875351c..62560d78 100644
--- a/zen/open_ssl.cpp
+++ b/zen/open_ssl.cpp
@@ -5,13 +5,18 @@
 // *****************************************************************************
 
 #include "open_ssl.h"
-#include <bit> //std::endian
-#include <stdexcept>
 #include "base64.h"
-#include "build_info.h"
+#include "thread.h"
 #include <openssl/pem.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+    #include <openssl/core_names.h>
+    #include <openssl/encoder.h>
+    #include <openssl/decoder.h>
+    #include <openssl/param_build.h>
+#endif
+
 
 using namespace zen;
 
@@ -29,7 +34,8 @@ void zen::openSslInit()
     //see apps_shutdown():     https://github.com/openssl/openssl/blob/master/apps/openssl.c
     //see Curl_ossl_cleanup(): https://github.com/curl/curl/blob/master/lib/vtls/openssl.c
 
-    //excplicitly init OpenSSL on main thread: seems to initialize atomically! But it still might help to avoid issues:
+        assert(runningOnMainThread()); 
+            //excplicitly init OpenSSL on main thread: seems to initialize atomically! But it still might help to avoid issues:
     [[maybe_unused]] const int rv = ::OPENSSL_init_ssl(OPENSSL_INIT_SSL_DEFAULT | OPENSSL_INIT_NO_LOAD_CONFIG, nullptr);
     assert(rv == 1); //https://www.openssl.org/docs/man1.1.0/ssl/OPENSSL_init_ssl.html
 }
@@ -101,67 +107,83 @@ std::shared_ptr<EVP_PKEY> generateRsaKeyPair(int bits) //throw SysError
 
 //================================================================================
 
-using BioToEvpFunc = EVP_PKEY* (*)(BIO* bp, EVP_PKEY** x, pem_password_cb* cb, void* u);
-
-std::shared_ptr<EVP_PKEY> streamToEvpKey(const std::string& keyStream, BioToEvpFunc bioToEvp, const char* functionName) //throw SysError
-{
-    BIO* bio = ::BIO_new_mem_buf(keyStream.c_str(), static_cast<int>(keyStream.size()));
-    if (!bio)
-        throw SysError(formatLastOpenSSLError("BIO_new_mem_buf"));
-    ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
-
-    if (EVP_PKEY* evp = bioToEvp(bio,      //BIO* bp
-                                 nullptr,  //EVP_PKEY** x
-                                 nullptr,  //pem_password_cb* cb
-                                 nullptr)) //void* u
-        return std::shared_ptr<EVP_PKEY>(evp, ::EVP_PKEY_free);
-    throw SysError(formatLastOpenSSLError(functionName));
-}
-
-
-using BioToRsaFunc = RSA* (*)(BIO* bp, RSA** x, pem_password_cb* cb, void* u);
-
-std::shared_ptr<EVP_PKEY> streamToEvpKey(const std::string& keyStream, BioToRsaFunc bioToRsa, const char* functionName) //throw SysError
-{
-    BIO* bio = ::BIO_new_mem_buf(keyStream.c_str(), static_cast<int>(keyStream.size()));
-    if (!bio)
-        throw SysError(formatLastOpenSSLError("BIO_new_mem_buf"));
-    ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
-
-    RSA* rsa = bioToRsa(bio,      //BIO* bp
-                        nullptr,  //RSA** x
-                        nullptr,  //pem_password_cb* cb
-                        nullptr); //void* u
-    if (!rsa)
-        throw SysError(formatLastOpenSSLError(functionName));
-    ZEN_ON_SCOPE_EXIT(::RSA_free(rsa));
-
-    EVP_PKEY* evp = ::EVP_PKEY_new();
-    if (!evp)
-        throw SysError(formatLastOpenSSLError("EVP_PKEY_new"));
-    std::shared_ptr<EVP_PKEY> sharedKey(evp, ::EVP_PKEY_free);
-
-    if (::EVP_PKEY_set1_RSA(evp, rsa) != 1) //no ownership transfer (internally ref-counted)
-        throw SysError(formatLastOpenSSLError("EVP_PKEY_set1_RSA"));
-
-    return sharedKey;
-}
-
-//--------------------------------------------------------------------------------
-
 std::shared_ptr<EVP_PKEY> streamToKey(const std::string& keyStream, RsaStreamType streamType, bool publicKey) //throw SysError
 {
     switch (streamType)
     {
         case RsaStreamType::pkix:
-            return publicKey ?
-                   streamToEvpKey(keyStream, ::PEM_read_bio_PUBKEY,     "PEM_read_bio_PUBKEY") :    //throw SysError
-                   streamToEvpKey(keyStream, ::PEM_read_bio_PrivateKey, "PEM_read_bio_PrivateKey"); //
+        {
+            BIO* bio = ::BIO_new_mem_buf(keyStream.c_str(), static_cast<int>(keyStream.size()));
+            if (!bio)
+                throw SysError(formatLastOpenSSLError("BIO_new_mem_buf"));
+            ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
+
+            if (EVP_PKEY* evp = (publicKey ?
+                                 ::PEM_read_bio_PUBKEY :
+                                 ::PEM_read_bio_PrivateKey)
+                                (bio,      //BIO* bp
+                                 nullptr,  //EVP_PKEY** x
+                                 nullptr,  //pem_password_cb* cb
+                                 nullptr)) //void* u
+                return std::shared_ptr<EVP_PKEY>(evp, ::EVP_PKEY_free);
+            throw SysError(formatLastOpenSSLError(publicKey ? "PEM_read_bio_PUBKEY" : "PEM_read_bio_PrivateKey"));
+        }
 
         case RsaStreamType::pkcs1:
-            return publicKey ?
-                   streamToEvpKey(keyStream, ::PEM_read_bio_RSAPublicKey,  "PEM_read_bio_RSAPublicKey") : //throw SysError
-                   streamToEvpKey(keyStream, ::PEM_read_bio_RSAPrivateKey, "PEM_read_bio_RSAPrivateKey"); //
+        {
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+            EVP_PKEY* evp = nullptr;
+            auto guardEvp = makeGuard<ScopeGuardRunMode::onExit>([&] { if (evp) ::EVP_PKEY_free(evp); });
+
+            const int selection = publicKey ? OSSL_KEYMGMT_SELECT_PUBLIC_KEY : OSSL_KEYMGMT_SELECT_PRIVATE_KEY;
+
+            OSSL_DECODER_CTX* decCtx = ::OSSL_DECODER_CTX_new_for_pkey(&evp,      //EVP_PKEY** pkey
+                                                                       "PEM",     //const char* input_type
+                                                                       nullptr,   //const char* input_struct
+                                                                       "RSA",     //const char* keytype
+                                                                       selection, //int selection
+                                                                       nullptr,   //OSSL_LIB_CTX* libctx
+                                                                       nullptr);  //const char* propquery
+            if (!decCtx)
+                throw SysError(formatLastOpenSSLError("OSSL_DECODER_CTX_new_for_pkey"));
+            ZEN_ON_SCOPE_EXIT(::OSSL_DECODER_CTX_free(decCtx));
+
+            //key stream is password-protected? => OSSL_DECODER_CTX_set_passphrase()
+
+            const unsigned char* keyBuf = reinterpret_cast<const unsigned char*>(keyStream.c_str());
+            size_t keyLen = keyStream.size();
+            if (::OSSL_DECODER_from_data(decCtx, &keyBuf, &keyLen) != 1)
+                throw SysError(formatLastOpenSSLError("OSSL_DECODER_from_data"));
+
+            guardEvp.dismiss();                                     //pass ownership
+            return std::shared_ptr<EVP_PKEY>(evp, ::EVP_PKEY_free); //
+#else
+            BIO* bio = ::BIO_new_mem_buf(keyStream.c_str(), static_cast<int>(keyStream.size()));
+            if (!bio)
+                throw SysError(formatLastOpenSSLError("BIO_new_mem_buf"));
+            ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
+
+            RSA* rsa = (publicKey ?
+                        ::PEM_read_bio_RSAPublicKey :
+                        ::PEM_read_bio_RSAPrivateKey)(bio,      //BIO* bp
+                                                      nullptr,  //RSA** x
+                                                      nullptr,  //pem_password_cb* cb
+                                                      nullptr); //void* u
+            if (!rsa)
+                throw SysError(formatLastOpenSSLError(publicKey ? "PEM_read_bio_RSAPublicKey" : "PEM_read_bio_RSAPrivateKey"));
+            ZEN_ON_SCOPE_EXIT(::RSA_free(rsa));
+
+            EVP_PKEY* evp = ::EVP_PKEY_new();
+            if (!evp)
+                throw SysError(formatLastOpenSSLError("EVP_PKEY_new"));
+            std::shared_ptr<EVP_PKEY> sharedKey(evp, ::EVP_PKEY_free);
+
+            if (::EVP_PKEY_set1_RSA(evp, rsa) != 1) //no ownership transfer (internally ref-counted)
+                throw SysError(formatLastOpenSSLError("EVP_PKEY_set1_RSA"));
+
+            return sharedKey;
+#endif
+        }
 
         case RsaStreamType::raw:
             break;
@@ -179,102 +201,113 @@ std::shared_ptr<EVP_PKEY> streamToKey(const std::string& keyStream, RsaStreamTyp
 
 //================================================================================
 
-using EvpToBioFunc = int (*)(BIO* bio, const EVP_PKEY* evp);
-
-std::string evpKeyToStream(const EVP_PKEY* evp, EvpToBioFunc evpToBio, const char* functionName) //throw SysError
-{
-    BIO* bio = ::BIO_new(BIO_s_mem());
-    if (!bio)
-        throw SysError(formatLastOpenSSLError("BIO_new"));
-    ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
-
-    if (evpToBio(bio, evp) != 1)
-        throw SysError(formatLastOpenSSLError(functionName));
-    //---------------------------------------------
-    const int keyLen = BIO_pending(bio);
-    if (keyLen < 0)
-        throw SysError(formatLastOpenSSLError("BIO_pending"));
-    if (keyLen == 0)
-        throw SysError(formatSystemError("BIO_pending", L"", L"Unexpected failure.")); //no more error details
-
-    std::string keyStream(keyLen, '\0');
-
-    if (::BIO_read(bio, &keyStream[0], keyLen) != keyLen)
-        throw SysError(formatLastOpenSSLError("BIO_read"));
-    return keyStream;
-}
-
-
-using RsaToBioFunc = int (*)(BIO* bp, const RSA* x);
-
-std::string evpKeyToStream(const EVP_PKEY* evp, RsaToBioFunc rsaToBio, const char* functionName) //throw SysError
-{
-    BIO* bio = ::BIO_new(BIO_s_mem());
-    if (!bio)
-        throw SysError(formatLastOpenSSLError("BIO_new"));
-    ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
-
-    const RSA* rsa = ::EVP_PKEY_get0_RSA(evp); //unowned reference!
-    if (!rsa)
-        throw SysError(formatLastOpenSSLError("EVP_PKEY_get0_RSA"));
-
-    if (rsaToBio(bio, rsa) != 1)
-        throw SysError(formatLastOpenSSLError(functionName));
-    //---------------------------------------------
-    const int keyLen = BIO_pending(bio);
-    if (keyLen < 0)
-        throw SysError(formatLastOpenSSLError("BIO_pending"));
-    if (keyLen == 0)
-        throw SysError(formatSystemError("BIO_pending", L"", L"Unexpected failure.")); //no more error details
-
-    std::string keyStream(keyLen, '\0');
-
-    if (::BIO_read(bio, &keyStream[0], keyLen) != keyLen)
-        throw SysError(formatLastOpenSSLError("BIO_read"));
-    return keyStream;
-}
-
-
-//fix OpenSSL API inconsistencies:
-int PEM_write_bio_PrivateKey2(BIO* bio, const EVP_PKEY* key)
-{
-    return ::PEM_write_bio_PrivateKey(bio,      //BIO* bp
-                                      key,      //const EVP_PKEY* x
-                                      nullptr,  //const EVP_CIPHER* enc
-                                      nullptr,  //const unsigned char* kstr
-                                      0,        //int klen
-                                      nullptr,  //pem_password_cb* cb
-                                      nullptr); //void* u
-}
-
-int PEM_write_bio_RSAPrivateKey2(BIO* bio, const RSA* rsa)
-{
-    return ::PEM_write_bio_RSAPrivateKey(bio,      //BIO* bp
-                                         rsa,      //const RSA* x
-                                         nullptr,  //const EVP_CIPHER* enc
-                                         nullptr,  //const unsigned char* kstr
-                                         0,        //int klen
-                                         nullptr,  //pem_password_cb* cb
-                                         nullptr); //void* u
-}
-
-int PEM_write_bio_RSAPublicKey2(BIO* bio, const RSA* rsa) { return ::PEM_write_bio_RSAPublicKey(bio, rsa); }
-
-//--------------------------------------------------------------------------------
-
 std::string keyToStream(const EVP_PKEY* evp, RsaStreamType streamType, bool publicKey) //throw SysError
 {
+    //assert(::EVP_PKEY_get_base_id(evp) == EVP_PKEY_RSA);
+
     switch (streamType)
     {
         case RsaStreamType::pkix:
-            return publicKey ?
-                   evpKeyToStream(evp, ::PEM_write_bio_PUBKEY,      "PEM_write_bio_PUBKEY") :    //throw SysError
-                   evpKeyToStream(evp, ::PEM_write_bio_PrivateKey2, "PEM_write_bio_PrivateKey"); //
+        {
+            //fix OpenSSL API inconsistencies:
+            auto PEM_write_bio_PrivateKey2 = [](BIO* bio, const EVP_PKEY* key)
+            {
+                return ::PEM_write_bio_PrivateKey(bio,      //BIO* bp
+                                                  key,      //const EVP_PKEY* x
+                                                  nullptr,  //const EVP_CIPHER* enc
+                                                  nullptr,  //const unsigned char* kstr
+                                                  0,        //int klen
+                                                  nullptr,  //pem_password_cb* cb
+                                                  nullptr); //void* u
+            };
+
+            BIO* bio = ::BIO_new(BIO_s_mem());
+            if (!bio)
+                throw SysError(formatLastOpenSSLError("BIO_new"));
+            ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
+
+            if ((publicKey ?
+                 ::PEM_write_bio_PUBKEY :
+                 PEM_write_bio_PrivateKey2)(bio, evp) != 1)
+                throw SysError(formatLastOpenSSLError(publicKey ? "PEM_write_bio_PUBKEY" : "PEM_write_bio_PrivateKey"));
+            //---------------------------------------------
+            const int keyLen = BIO_pending(bio);
+            if (keyLen < 0)
+                throw SysError(formatLastOpenSSLError("BIO_pending"));
+            if (keyLen == 0)
+                throw SysError(formatSystemError("BIO_pending", L"", L"Unexpected failure.")); //no more error details
+
+            std::string keyStream(keyLen, '\0');
+
+            if (::BIO_read(bio, &keyStream[0], keyLen) != keyLen)
+                throw SysError(formatLastOpenSSLError("BIO_read"));
+            return keyStream;
+        }
 
         case RsaStreamType::pkcs1:
-            return publicKey ?
-                   evpKeyToStream(evp, ::PEM_write_bio_RSAPublicKey2,  "PEM_write_bio_RSAPublicKey") : //throw SysError
-                   evpKeyToStream(evp, ::PEM_write_bio_RSAPrivateKey2, "PEM_write_bio_RSAPrivateKey"); //
+        {
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+            const int selection = publicKey ? OSSL_KEYMGMT_SELECT_PUBLIC_KEY : OSSL_KEYMGMT_SELECT_PRIVATE_KEY;
+
+            OSSL_ENCODER_CTX* encCtx = ::OSSL_ENCODER_CTX_new_for_pkey(evp,       //const EVP_PKEY* pkey
+                                                                       selection, //int selection
+                                                                       "PEM",     //const char* output_type
+                                                                       nullptr,   //const char* output_structure
+                                                                       nullptr);  //const char* propquery
+            if (!encCtx)
+                throw SysError(formatLastOpenSSLError("OSSL_ENCODER_CTX_new_for_pkey"));
+            ZEN_ON_SCOPE_EXIT(::OSSL_ENCODER_CTX_free(encCtx));
+
+            //password-protect stream? => OSSL_ENCODER_CTX_set_passphrase()
+
+            unsigned char* keyBuf = nullptr;
+            size_t keyLen = 0;
+            if (::OSSL_ENCODER_to_data(encCtx, &keyBuf, &keyLen) != 1)
+                throw SysError(formatLastOpenSSLError("OSSL_ENCODER_to_data"));
+            ZEN_ON_SCOPE_EXIT(::OPENSSL_free(keyBuf));
+
+            return {reinterpret_cast<const char*>(keyBuf), keyLen};
+#else
+            //fix OpenSSL API inconsistencies:
+            auto PEM_write_bio_RSAPrivateKey2 = [](BIO* bio, const RSA* rsa)
+            {
+                return ::PEM_write_bio_RSAPrivateKey(bio,      //BIO* bp
+                                                     rsa,      //const RSA* x
+                                                     nullptr,  //const EVP_CIPHER* enc
+                                                     nullptr,  //const unsigned char* kstr
+                                                     0,        //int klen
+                                                     nullptr,  //pem_password_cb* cb
+                                                     nullptr); //void* u
+            };
+            auto PEM_write_bio_RSAPublicKey2 = [](BIO* bio, const RSA* rsa) { return ::PEM_write_bio_RSAPublicKey(bio, rsa); };
+
+            BIO* bio = ::BIO_new(BIO_s_mem());
+            if (!bio)
+                throw SysError(formatLastOpenSSLError("BIO_new"));
+            ZEN_ON_SCOPE_EXIT(::BIO_free_all(bio));
+
+            const RSA* rsa = ::EVP_PKEY_get0_RSA(evp); //unowned reference!
+            if (!rsa)
+                throw SysError(formatLastOpenSSLError("EVP_PKEY_get0_RSA"));
+
+            if ((publicKey ?
+                 PEM_write_bio_RSAPublicKey2 :
+                 PEM_write_bio_RSAPrivateKey2)(bio, rsa) != 1)
+                throw SysError(formatLastOpenSSLError(publicKey ? "PEM_write_bio_RSAPublicKey" : "PEM_write_bio_RSAPrivateKey"));
+            //---------------------------------------------
+            const int keyLen = BIO_pending(bio);
+            if (keyLen < 0)
+                throw SysError(formatLastOpenSSLError("BIO_pending"));
+            if (keyLen == 0)
+                throw SysError(formatSystemError("BIO_pending", L"", L"Unexpected failure.")); //no more error details
+
+            std::string keyStream(keyLen, '\0');
+
+            if (::BIO_read(bio, &keyStream[0], keyLen) != keyLen)
+                throw SysError(formatLastOpenSSLError("BIO_read"));
+            return keyStream;
+#endif
+        }
 
         case RsaStreamType::raw:
             break;
@@ -373,266 +406,6 @@ void zen::verifySignature(const std::string& message, const std::string& signatu
 }
 
 
-namespace
-{
-std::wstring getSslErrorLiteral(int ec)
-{
-    switch (ec)
-    {
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_NONE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_SSL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_READ);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_WRITE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_X509_LOOKUP);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_SYSCALL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_ZERO_RETURN);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_CONNECT);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ACCEPT);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ASYNC);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_ASYNC_JOB);
-            ZEN_CHECK_CASE_FOR_CONSTANT(SSL_ERROR_WANT_CLIENT_HELLO_CB);
-
-        default:
-            return L"SSL error " + numberTo<std::wstring>(ec);
-    }
-}
-
-
-std::wstring formatX509ErrorCode(long ec)
-{
-    switch (ec)
-    {
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_OK);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNSPECIFIED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_GET_CRL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_DECRYPT_CERT_SIGNATURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_DECRYPT_CRL_SIGNATURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_DECODE_ISSUER_PUBLIC_KEY);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_SIGNATURE_FAILURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CRL_SIGNATURE_FAILURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_NOT_YET_VALID);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_HAS_EXPIRED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CRL_NOT_YET_VALID);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CRL_HAS_EXPIRED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_ERROR_IN_CERT_NOT_BEFORE_FIELD);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_ERROR_IN_CERT_NOT_AFTER_FIELD);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_ERROR_IN_CRL_LAST_UPDATE_FIELD);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_ERROR_IN_CRL_NEXT_UPDATE_FIELD);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OUT_OF_MEM);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_CHAIN_TOO_LONG);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_REVOKED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_CA);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PATH_LENGTH_EXCEEDED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_PURPOSE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_UNTRUSTED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CERT_REJECTED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUBJECT_ISSUER_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_AKID_SKID_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_AKID_ISSUER_SERIAL_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_KEYUSAGE_NO_CERTSIGN);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNABLE_TO_GET_CRL_ISSUER);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNHANDLED_CRITICAL_EXTENSION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_KEYUSAGE_NO_CRL_SIGN);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNHANDLED_CRITICAL_CRL_EXTENSION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_NON_CA);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PROXY_PATH_LENGTH_EXCEEDED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_KEYUSAGE_NO_DIGITAL_SIGNATURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PROXY_CERTIFICATES_NOT_ALLOWED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_EXTENSION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_POLICY_EXTENSION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_NO_EXPLICIT_POLICY);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_DIFFERENT_CRL_SCOPE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNSUPPORTED_EXTENSION_FEATURE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNNESTED_RESOURCE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PERMITTED_VIOLATION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_EXCLUDED_VIOLATION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUBTREE_MINMAX);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_APPLICATION_VERIFICATION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_UNSUPPORTED_NAME_SYNTAX);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CRL_PATH_VALIDATION_ERROR);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PATH_LOOP);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_INVALID_VERSION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_INVALID_ALGORITHM);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_INVALID_CURVE);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_INVALID_SIGNATURE_ALGORITHM);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_LOS_NOT_ALLOWED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_SUITE_B_CANNOT_SIGN_P_384_WITH_P_256);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_HOSTNAME_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_EMAIL_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_IP_ADDRESS_MISMATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_DANE_NO_MATCH);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_EE_KEY_TOO_SMALL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CA_KEY_TOO_SMALL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_CA_MD_TOO_WEAK);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_INVALID_CALL);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_STORE_LOOKUP);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_NO_VALID_SCTS);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_PROXY_SUBJECT_NAME_VIOLATION);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_VERIFY_NEEDED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_VERIFY_FAILED);
-            ZEN_CHECK_CASE_FOR_CONSTANT(X509_V_ERR_OCSP_CERT_UNKNOWN);
-
-        default:
-            return replaceCpy<std::wstring>(L"X509 error %x", L"%x", numberTo<std::wstring>(ec));
-    }
-}
-}
-
-class TlsContext::Impl
-{
-public:
-    Impl(int socket, //throw SysError
-         const std::string& server,
-         const Zstring* caCertFilePath /*optional: enable certificate validation*/)
-    {
-        ZEN_ON_SCOPE_FAIL(cleanup(); /*destructor call would lead to member double clean-up!!!*/);
-
-        ctx_ = ::SSL_CTX_new(::TLS_client_method());
-        if (!ctx_)
-            throw SysError(formatLastOpenSSLError("SSL_CTX_new"));
-
-        ssl_ = ::SSL_new(ctx_);
-        if (!ssl_)
-            throw SysError(formatLastOpenSSLError("SSL_new"));
-
-        BIO* bio = ::BIO_new_socket(socket, BIO_NOCLOSE);
-        if (!bio)
-            throw SysError(formatLastOpenSSLError("BIO_new_socket"));
-        ::SSL_set0_rbio(ssl_, bio); //pass ownership
-
-        if (::BIO_up_ref(bio) != 1)
-            throw SysError(formatLastOpenSSLError("BIO_up_ref"));
-        ::SSL_set0_wbio(ssl_, bio); //pass ownership
-
-        assert(::SSL_get_mode(ssl_) == SSL_MODE_AUTO_RETRY); //verify OpenSSL default
-        ::SSL_set_mode(ssl_, SSL_MODE_ENABLE_PARTIAL_WRITE);
-
-        if (::SSL_set_tlsext_host_name(ssl_, server.c_str()) != 1) //enable SNI (Server Name Indication)
-            throw SysError(formatLastOpenSSLError("SSL_set_tlsext_host_name"));
-
-        if (caCertFilePath)
-        {
-            if (!::SSL_CTX_load_verify_locations(ctx_, utfTo<std::string>(*caCertFilePath).c_str(), nullptr))
-                throw SysError(formatLastOpenSSLError("SSL_CTX_load_verify_locations"));
-            //alternative: SSL_CTX_set_default_verify_paths(): use OpenSSL default paths considering SSL_CERT_FILE environment variable
-
-            //1. enable check for valid certificate: see SSL_get_verify_result()
-            ::SSL_set_verify(ssl_, SSL_VERIFY_PEER, nullptr);
-
-            //2. enable check that the certificate matches our host: see SSL_get_verify_result()
-            if (::SSL_set1_host(ssl_, server.c_str()) != 1) //no ownership transfer
-                throw SysError(formatSystemError("SSL_set1_host", L"", L"Unexpected failure.")); //no more error details
-        }
-
-        const int rv = ::SSL_connect(ssl_); //implicitly calls SSL_set_connect_state()
-        if (rv != 1)
-            throw SysError(formatLastOpenSSLError("SSL_connect") + L' ' + getSslErrorLiteral(::SSL_get_error(ssl_, rv)));
-
-        if (caCertFilePath)
-        {
-            const long verifyResult = ::SSL_get_verify_result(ssl_);
-            if (verifyResult != X509_V_OK)
-                throw SysError(formatSystemError("SSL_get_verify_result", formatX509ErrorCode(verifyResult), L""));
-        }
-    }
-
-    ~Impl()
-    {
-        //"SSL_shutdown() must not be called if a previous fatal error has occurred on a connection"
-        const bool scopeFail = std::uncaught_exceptions() > exeptionCount_;
-        if (!scopeFail)
-        {
-            //"It is acceptable for an application to only send its shutdown alert and then close
-            //the underlying connection without waiting for the peer's response."
-            [[maybe_unused]] const int rv = ::SSL_shutdown(ssl_);
-            assert(rv == 0); //"the close_notify was sent but the peer did not send it back yet."
-        }
-
-        cleanup();
-    }
-
-    size_t tryRead(void* buffer, size_t bytesToRead) //throw SysError; may return short, only 0 means EOF!
-    {
-        if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
-
-        size_t bytesReceived = 0;
-        const int rv = ::SSL_read_ex(ssl_, buffer, bytesToRead, &bytesReceived);
-        if (rv != 1)
-        {
-            const int sslError = ::SSL_get_error(ssl_, rv);
-            if (sslError == SSL_ERROR_ZERO_RETURN)
-                return 0; //EOF + close_notify alert
-
-#if OPENSSL_VERSION_NUMBER >= 0x30000000L /*OpenSSL 3.0.0*/ || \
-    OPENSSL_VERSION_NUMBER == 0x1010105fL /*OpenSSL 1.1.1e*/
-            const auto ec = ::ERR_peek_last_error();
-            if (sslError == SSL_ERROR_SSL && ERR_GET_REASON(ec) == SSL_R_UNEXPECTED_EOF_WHILE_READING) //EOF: only expected for HTTP/1.0
-#else //obsolete handling: https://github.com/openssl/openssl/issues/10880#issuecomment-575746226
-            if ((sslError == SSL_ERROR_SYSCALL && ::ERR_peek_last_error() == 0)) //EOF: only expected for HTTP/1.0
-#endif
-                return 0;
-
-            throw SysError(formatLastOpenSSLError("SSL_read_ex") + L' ' + getSslErrorLiteral(sslError));
-        }
-        assert(bytesReceived > 0); //SSL_read_ex() considers EOF an error!
-        if (bytesReceived > bytesToRead) //better safe than sorry
-            throw SysError(formatSystemError("SSL_read_ex", L"", L"Buffer overflow."));
-
-        return bytesReceived; //"zero indicates end of file"
-    }
-
-    size_t tryWrite(const void* buffer, size_t bytesToWrite) //throw SysError; may return short! CONTRACT: bytesToWrite > 0
-    {
-        if (bytesToWrite == 0)
-            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
-
-        size_t bytesWritten = 0;
-        const int rv = ::SSL_write_ex(ssl_, buffer, bytesToWrite, &bytesWritten);
-        if (rv != 1)
-            throw SysError(formatLastOpenSSLError("SSL_write_ex") + L' ' + getSslErrorLiteral(::SSL_get_error(ssl_, rv)));
-
-        if (bytesWritten > bytesToWrite)
-            throw SysError(formatSystemError("SSL_write_ex", L"", L"Buffer overflow."));
-        if (bytesWritten == 0)
-            throw SysError(formatSystemError("SSL_write_ex", L"", L"Zero bytes processed."));
-
-        return bytesWritten;
-    }
-
-private:
-    void cleanup()
-    {
-        if (ssl_)
-            ::SSL_free(ssl_);
-
-        if (ctx_)
-            ::SSL_CTX_free(ctx_);
-    }
-
-    Impl           (const Impl&) = delete;
-    Impl& operator=(const Impl&) = delete;
-
-    SSL_CTX* ctx_ = nullptr;
-    SSL*     ssl_ = nullptr;
-    const int exeptionCount_ = std::uncaught_exceptions();
-};
-
-
-zen::TlsContext::TlsContext(int socket, const Zstring& server, const Zstring* caCertFilePath) :
-    pimpl_(std::make_unique<Impl>(socket, utfTo<std::string>(server), caCertFilePath)) {} //throw SysError
-zen::TlsContext::~TlsContext() {}
-size_t zen::TlsContext::tryRead (      void* buffer, size_t bytesToRead ) { return pimpl_->tryRead (buffer,  bytesToRead); } //throw SysError
-size_t zen::TlsContext::tryWrite(const void* buffer, size_t bytesToWrite) { return pimpl_->tryWrite(buffer, bytesToWrite); } //throw SysError
-
-
 bool zen::isPuttyKeyStream(const std::string& keyStream)
 {
     std::string firstLine(keyStream.begin(), std::find_if(keyStream.begin(), keyStream.end(), isLineBreak<char>));
@@ -727,8 +500,8 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
         const auto block2 = std::string("\0\0\0\1", 4) + passphrase;
 
         unsigned char key[2 * SHA_DIGEST_LENGTH] = {};
-        SHA1(reinterpret_cast<const unsigned char*>(block1.c_str()), block1.size(), &key[0]);                 //no-fail
-        SHA1(reinterpret_cast<const unsigned char*>(block2.c_str()), block2.size(), &key[SHA_DIGEST_LENGTH]); //
+        ::SHA1(reinterpret_cast<const unsigned char*>(block1.c_str()), block1.size(), &key[0]);                 //no-fail
+        ::SHA1(reinterpret_cast<const unsigned char*>(block2.c_str()), block2.size(), &key[SHA_DIGEST_LENGTH]); //
 
         EVP_CIPHER_CTX* cipCtx = ::EVP_CIPHER_CTX_new();
         if (!cipCtx)
@@ -771,7 +544,7 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
         macKeyBlob += passphrase;
 
     unsigned char macKey[SHA_DIGEST_LENGTH] = {};
-    SHA1(reinterpret_cast<const unsigned char*>(macKeyBlob.c_str()), macKeyBlob.size(), &macKey[0]); //no-fail
+    ::SHA1(reinterpret_cast<const unsigned char*>(macKeyBlob.c_str()), macKeyBlob.size(), &macKey[0]); //no-fail
 
     auto numToBeString = [](size_t n) -> std::string
     {
@@ -886,6 +659,40 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
             throw SysError(formatLastOpenSSLError("BN_mod"));
         //----------------------------------------------------------
 
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+        OSSL_PARAM_BLD* paramBld = ::OSSL_PARAM_BLD_new();
+        if (!paramBld)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_new"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_BLD_free(paramBld));
+
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_N, n.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(n)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_E, e.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(e)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_D, d.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(d)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_FACTOR1, p.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(p)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_FACTOR2, q.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(q)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_EXPONENT1,    dmp1.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(dmp1)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_EXPONENT2,    dmq1.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(dmq1)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_RSA_COEFFICIENT1, iqmp.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(iqmp)"));
+
+        OSSL_PARAM* sslParams = ::OSSL_PARAM_BLD_to_param(paramBld);
+        if (!sslParams)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_to_param"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_free(sslParams));
+
+
+        EVP_PKEY_CTX* evpCtx = ::EVP_PKEY_CTX_new_from_name(nullptr, "RSA", nullptr);
+        if (!evpCtx)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_CTX_new_from_name(RSA)"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_CTX_free(evpCtx));
+
+        if (::EVP_PKEY_fromdata_init(evpCtx) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata_init"));
+
+        EVP_PKEY* evp = nullptr;
+        if (::EVP_PKEY_fromdata(evpCtx, &evp, EVP_PKEY_KEYPAIR, sslParams) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_free(evp));
+#else
         RSA* rsa = ::RSA_new();
         if (!rsa)
             throw SysError(formatLastOpenSSLError("RSA_new"));
@@ -907,7 +714,7 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
 
         if (::EVP_PKEY_set1_RSA(evp, rsa) != 1) //no ownership transfer (internally ref-counted)
             throw SysError(formatLastOpenSSLError("EVP_PKEY_set1_RSA"));
-
+#endif
         return keyToStream(evp, RsaStreamType::pkix, false /*publicKey*/); //throw SysError
     }
     //----------------------------------------------------------
@@ -919,7 +726,37 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
         std::unique_ptr<BIGNUM, BnFree> pub = extractBigNumPub (); //
         std::unique_ptr<BIGNUM, BnFree> pri = extractBigNumPriv(); //
         //----------------------------------------------------------
-
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+        OSSL_PARAM_BLD* paramBld = ::OSSL_PARAM_BLD_new();
+        if (!paramBld)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_new"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_BLD_free(paramBld));
+
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_FFC_P,      p.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(p)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_FFC_Q,      q.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(q)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_FFC_G,      g.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(g)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_PUB_KEY,  pub.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(pub)"));
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_PRIV_KEY, pri.get()) != 1) throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(pri)"));
+
+        OSSL_PARAM* sslParams = ::OSSL_PARAM_BLD_to_param(paramBld);
+        if (!sslParams)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_to_param"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_free(sslParams));
+
+
+        EVP_PKEY_CTX* evpCtx = ::EVP_PKEY_CTX_new_from_name(nullptr, "DSA", nullptr);
+        if (!evpCtx)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_CTX_new_from_name(DSA)"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_CTX_free(evpCtx));
+
+        if (::EVP_PKEY_fromdata_init(evpCtx) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata_init"));
+
+        EVP_PKEY* evp = nullptr;
+        if (::EVP_PKEY_fromdata(evpCtx, &evp, EVP_PKEY_KEYPAIR, sslParams) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_free(evp));
+#else
         DSA* dsa = ::DSA_new();
         if (!dsa)
             throw SysError(formatLastOpenSSLError("DSA_new"));
@@ -938,7 +775,7 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
 
         if (::EVP_PKEY_set1_DSA(evp, dsa) != 1) //no ownership transfer (internally ref-counted)
             throw SysError(formatLastOpenSSLError("EVP_PKEY_set1_DSA"));
-
+#endif
         return keyToStream(evp, RsaStreamType::pkix, false /*publicKey*/); //throw SysError
     }
     //----------------------------------------------------------
@@ -953,7 +790,51 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
         const std::string pointStream = extractStringPub();
         std::unique_ptr<BIGNUM, BnFree> pri = extractBigNumPriv(); //throw SysError
         //----------------------------------------------------------
+#if OPENSSL_VERSION_NUMBER >= 0x30000000L
+        const char* groupName = [&]
+        {
+            if (algoShort == "nistp256")
+                return SN_X9_62_prime256v1; //same as SECG secp256r1
+            if (algoShort == "nistp384")
+                return SN_secp384r1;
+            if (algoShort == "nistp521")
+                return SN_secp521r1;
+            throw SysError(L"Unknown elliptic curve: " + utfTo<std::wstring>(algorithm));
+        }();
+
+        OSSL_PARAM_BLD* paramBld = ::OSSL_PARAM_BLD_new();
+        if (!paramBld)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_new"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_BLD_free(paramBld));
+
+        if (::OSSL_PARAM_BLD_push_utf8_string(paramBld, OSSL_PKEY_PARAM_GROUP_NAME, groupName, 0) != 1)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_utf8_string(group)"));
+
+        if (::OSSL_PARAM_BLD_push_octet_string(paramBld, OSSL_PKEY_PARAM_PUB_KEY, &pointStream[0], pointStream.size()) != 1)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_octet_string(pub)"));
 
+        if (::OSSL_PARAM_BLD_push_BN(paramBld, OSSL_PKEY_PARAM_PRIV_KEY, pri.get()) != 1)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_push_BN(priv)"));
+
+        OSSL_PARAM* sslParams = ::OSSL_PARAM_BLD_to_param(paramBld);
+        if (!sslParams)
+            throw SysError(formatLastOpenSSLError("OSSL_PARAM_BLD_to_param"));
+        ZEN_ON_SCOPE_EXIT(::OSSL_PARAM_free(sslParams));
+
+
+        EVP_PKEY_CTX* evpCtx = ::EVP_PKEY_CTX_new_from_name(nullptr, "EC", nullptr);
+        if (!evpCtx)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_CTX_new_from_name(EC)"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_CTX_free(evpCtx));
+
+        if (::EVP_PKEY_fromdata_init(evpCtx) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata_init"));
+
+        EVP_PKEY* evp = nullptr;
+        if (::EVP_PKEY_fromdata(evpCtx, &evp, EVP_PKEY_KEYPAIR, sslParams) != 1)
+            throw SysError(formatLastOpenSSLError("EVP_PKEY_fromdata"));
+        ZEN_ON_SCOPE_EXIT(::EVP_PKEY_free(evp));
+#else
         const int curveNid = [&]
         {
             if (algoShort == "nistp256")
@@ -999,7 +880,7 @@ std::string zen::convertPuttyKeyToPkix(const std::string& keyStream, const std::
 
         if (::EVP_PKEY_set1_EC_KEY(evp, ecKey) != 1) //no ownership transfer (internally ref-counted)
             throw SysError(formatLastOpenSSLError("EVP_PKEY_set1_EC_KEY"));
-
+#endif
         return keyToStream(evp, RsaStreamType::pkix, false /*publicKey*/); //throw SysError
     }
     //----------------------------------------------------------
diff --git a/zen/open_ssl.h b/zen/open_ssl.h
index 2b0c7245..d1b823de 100644
--- a/zen/open_ssl.h
+++ b/zen/open_ssl.h
@@ -36,23 +36,6 @@ std::string convertRsaKey(const std::string& keyStream, RsaStreamType typeFrom,
 
 bool isPuttyKeyStream(const std::string& keyStream);
 std::string convertPuttyKeyToPkix(const std::string& keyStream, const std::string& passphrase); //throw SysError
-
-
-class TlsContext
-{
-public:
-    TlsContext(int socket, //throw SysError
-               const Zstring& server,
-               const Zstring* caCertFilePath /*optional: enable certificate validation*/);
-    ~TlsContext();
-
-    size_t tryRead(       void* buffer, size_t bytesToRead ); //throw SysError; may return short, only 0 means EOF!
-    size_t tryWrite(const void* buffer, size_t bytesToWrite); //throw SysError; may return short! CONTRACT: bytesToWrite > 0
-
-private:
-    class Impl;
-    const std::unique_ptr<Impl> pimpl_;
-};
 }
 
 #endif //OPEN_SSL_H_801974580936508934568792347506
diff --git a/zen/stream_buffer.h b/zen/stream_buffer.h
new file mode 100644
index 00000000..8b8cd0d7
--- /dev/null
+++ b/zen/stream_buffer.h
@@ -0,0 +1,161 @@
+// *****************************************************************************
+// * This file is part of the FreeFileSync project. It is distributed under    *
+// * GNU General Public License: https://www.gnu.org/licenses/gpl-3.0          *
+// * Copyright (C) Zenju (zenju AT freefilesync DOT org) - All Rights Reserved *
+// *****************************************************************************
+
+#ifndef STREAM_BUFFER_H_08492572089560298
+#define STREAM_BUFFER_H_08492572089560298
+
+#include <condition_variable>
+#include "ring_buffer.h"
+#include "string_tools.h"
+
+
+namespace zen
+{
+/*   implement streaming API on top of libcurl's icky callback-based design
+        => support copying arbitrarily-large files: https://freefilesync.org/forum/viewtopic.php?t=4471
+        => maximum performance through async processing (prefetching + output buffer!)
+        => cost per worker thread creation ~ 1/20 ms                                         */
+class AsyncStreamBuffer
+{
+public:
+    explicit AsyncStreamBuffer(size_t bufferSize) : bufSize_(bufferSize) { ringBuf_.reserve(bufferSize); }
+
+    //context of input thread, blocking
+    //return "bytesToRead" bytes unless end of stream!
+    size_t read(void* buffer, size_t bytesToRead) //throw <write error>
+    {
+        if (bytesToRead == 0) //"read() with a count of 0 returns zero" => indistinguishable from end of file! => check!
+            throw std::logic_error("Contract violation! " + std::string(__FILE__) + ':' + numberTo<std::string>(__LINE__));
+
+        auto       it    = static_cast<std::byte*>(buffer);
+        const auto itEnd = it + bytesToRead;
+
+        for (std::unique_lock dummy(lockStream_); it != itEnd;)
+        {
+            assert(!errorRead_);
+            conditionBytesWritten_.wait(dummy, [this] { return errorWrite_ || !ringBuf_.empty() || eof_; });
+
+            if (errorWrite_)
+                std::rethrow_exception(errorWrite_); //throw <write error>
+
+            const size_t junkSize = std::min(static_cast<size_t>(itEnd - it), ringBuf_.size());
+            ringBuf_.extract_front(it, it + junkSize);
+            it += junkSize;
+
+            conditionBytesRead_.notify_all();
+
+            if (eof_) //end of file
+                break;
+        }
+
+        const size_t bytesRead = it - static_cast<std::byte*>(buffer);
+        totalBytesRead_ += bytesRead;
+        return bytesRead;
+    }
+
+    //context of output thread, blocking
+    void write(const void* buffer, size_t bytesToWrite) //throw <read error>
+    {
+        totalBytesWritten_ += bytesToWrite; //bytes already processed as far as raw FTP access is concerned
+
+        auto       it    = static_cast<const std::byte*>(buffer);
+        const auto itEnd = it + bytesToWrite;
+
+        for (std::unique_lock dummy(lockStream_); it != itEnd;)
+        {
+            assert(!eof_ && !errorWrite_);
+            /*  => can't use InterruptibleThread's interruptibleWait() :(
+                -> AsyncStreamBuffer is used for input and output streaming
+                => both AsyncStreamBuffer::write()/read() would have to implement interruptibleWait()
+                => one of these usually called from main thread
+                => but interruptibleWait() cannot be called from main thread!          */
+            conditionBytesRead_.wait(dummy, [this] { return errorRead_ || ringBuf_.size() < bufSize_; });
+
+            if (errorRead_)
+                std::rethrow_exception(errorRead_); //throw <read error>
+
+            const size_t junkSize = std::min(static_cast<size_t>(itEnd - it), bufSize_ - ringBuf_.size());
+            ringBuf_.insert_back(it, it + junkSize);
+            it += junkSize;
+
+            conditionBytesWritten_.notify_all();
+        }
+    }
+
+    //context of output thread
+    void closeStream()
+    {
+        {
+            std::lock_guard dummy(lockStream_);
+            assert(!eof_ && !errorWrite_);
+            eof_ = true;
+        }
+        conditionBytesWritten_.notify_all();
+    }
+
+    //context of input thread
+    void setReadError(const std::exception_ptr& error)
+    {
+        {
+            std::lock_guard dummy(lockStream_);
+            assert(!errorRead_);
+            if (!errorRead_)
+                errorRead_ = error;
+        }
+        conditionBytesRead_.notify_all();
+    }
+
+    //context of output thread
+    void setWriteError(const std::exception_ptr& error)
+    {
+        {
+            std::lock_guard dummy(lockStream_);
+            assert(!errorWrite_);
+            if (!errorWrite_)
+                errorWrite_ = error;
+        }
+        conditionBytesWritten_.notify_all();
+    }
+
+    //context of *output* thread
+    void checkReadErrors() //throw <read error>
+    {
+        std::lock_guard dummy(lockStream_);
+        if (errorRead_)
+            std::rethrow_exception(errorRead_); //throw <read error>
+    }
+
+#if 0 //function not needed: when EOF is reached (without errors), reading is done => no further error can occur!
+    void checkWriteErrors() //throw <write error>
+    {
+        std::lock_guard dummy(lockStream_);
+        if (errorWrite_)
+            std::rethrow_exception(errorWrite_); //throw <write error>
+    }
+#endif
+
+    uint64_t getTotalBytesWritten() const { return totalBytesWritten_; }
+    uint64_t getTotalBytesRead   () const { return totalBytesRead_; }
+
+private:
+    AsyncStreamBuffer           (const AsyncStreamBuffer&) = delete;
+    AsyncStreamBuffer& operator=(const AsyncStreamBuffer&) = delete;
+
+    const size_t bufSize_;
+    std::mutex lockStream_;
+    RingBuffer<std::byte> ringBuf_; //prefetch/output buffer
+    bool eof_ = false;
+    std::exception_ptr errorWrite_;
+    std::exception_ptr errorRead_;
+    std::condition_variable conditionBytesWritten_;
+    std::condition_variable conditionBytesRead_;
+
+    std::atomic<uint64_t> totalBytesWritten_{0}; //std:atomic is uninitialized by default!
+    std::atomic<uint64_t> totalBytesRead_   {0}; //
+};
+}
+
+#endif //STREAM_BUFFER_H_08492572089560298
diff --git a/zen/string_base.h b/zen/string_base.h
index 5c17fb47..693ce118 100644
--- a/zen/string_base.h
+++ b/zen/string_base.h
@@ -10,7 +10,6 @@
 #include <algorithm>
 #include <atomic>
 #include "string_tools.h"
-#include "legacy_compiler.h" //constinit
 
 
 //Zbase - a policy based string class optimizing performance and flexibility
@@ -298,6 +297,11 @@ private:
     Zbase& operator=   (int) = delete; //detect usage errors by creating an intentional ambiguity with "Char"
     Zbase& operator+=  (int) = delete; //
     void   push_back   (int) = delete; //
+    Zbase              (std::nullptr_t) = delete;
+    Zbase(size_t count, std::nullptr_t) = delete;
+    Zbase& operator=   (std::nullptr_t) = delete;
+    Zbase& operator+=  (std::nullptr_t) = delete;
+    void   push_back   (std::nullptr_t) = delete;
 
     Char* rawStr_;
 };
diff --git a/zen/sys_info.cpp b/zen/sys_info.cpp
index edb8dd9d..54a5ecae 100644
--- a/zen/sys_info.cpp
+++ b/zen/sys_info.cpp
@@ -28,7 +28,7 @@ Zstring zen::getLoginUser() //throw FileError
 {
     const uid_t userIdNo = ::getuid(); //never fails
 
-    if (userIdNo != 0) //nofail; root(0) => consider as request for elevation, NOT impersonation
+    if (userIdNo != 0) //nofail; non-root
     {
         std::vector<char> buf(std::max<long>(10000, ::sysconf(_SC_GETPW_R_SIZE_MAX))); //::sysconf may return long(-1)
         passwd buf2 = {};
@@ -45,7 +45,7 @@ Zstring zen::getLoginUser() //throw FileError
 
         return pwsEntry->pw_name;
     }
-    //else root(0): what now!?
+    //else: root(0) => consider as request for elevation, NOT impersonation!
 
     //getlogin() is smarter than simply evaluating $LOGNAME! even in contexts without
     //$LOGNAME, e.g. "sudo su" on Ubuntu, it returns the correct non-root user!
@@ -72,6 +72,29 @@ Zstring zen::getLoginUser() //throw FileError
 }
 
 
+Zstring zen::getUserDescription() //throw FileError
+{
+    const Zstring userName     = getLoginUser(); //throw FileError
+    const Zstring computerName = []() -> Zstring //throw FileError
+    {
+        std::vector<char> buf(10000);
+        if (::gethostname(&buf[0], buf.size()) != 0)
+            THROW_LAST_FILE_ERROR(_("Cannot get process information."), "gethostname");
+
+        Zstring hostName = &buf[0];
+        if (endsWithAsciiNoCase(hostName, ".local")) //strip fluff (macOS) => apparently not added on Linux?
+            hostName = beforeLast(hostName, '.', IfNotFoundReturn::none);
+
+        return hostName;
+    }();
+
+    if (contains(getUpperCase(computerName), getUpperCase(userName)))
+        return userName; //no need for text duplication! e.g. "Zenju (Zenju-PC)"
+
+    return userName + Zstr(" (") + computerName + Zstr(')'); //e.g. "Admin (Zenju-PC)"
+}
+
+
 namespace
 {
 }
diff --git a/zen/sys_info.h b/zen/sys_info.h
index 0126ad2f..0393e1fb 100644
--- a/zen/sys_info.h
+++ b/zen/sys_info.h
@@ -15,6 +15,8 @@ namespace zen
 //COM needs to be initialized before calling any of these functions! CoInitializeEx/CoUninitialize
 
 Zstring getLoginUser(); //throw FileError
+Zstring getUserDescription();//throw FileError
+
 
 struct ComputerModel
 {
diff --git a/zen/type_traits.h b/zen/type_traits.h
index a4194c05..aca80393 100644
--- a/zen/type_traits.h
+++ b/zen/type_traits.h
@@ -184,4 +184,10 @@ LessDescending<Predicate> makeSortDirection(Predicate pred, std::false_type) { r
     template<class T> constexpr bool HasMemberTypeV_##TYPENAME = HasMemberType_##TYPENAME<T>::value;
 }
 
+
+//---------------------------------------------------------------------------
+//ZEN macro consistency checks: => place in most-used header!
+
+
+
 #endif //TYPE_TRAITS_H_3425628658765467
diff --git a/zen/zstring.cpp b/zen/zstring.cpp
index c9861219..34d52b2c 100644
--- a/zen/zstring.cpp
+++ b/zen/zstring.cpp
@@ -166,10 +166,10 @@ std::weak_ordering compareNoCaseUtf8(const char* lhs, size_t lhsLen, const char*
 
 std::weak_ordering compareNatural(const Zstring& lhs, const Zstring& rhs)
 {
-    //Unicode normal forms:
-    //      Windows: CompareString() already ignores NFD/NFC differences: nice...
-    //      Linux:  g_unichar_toupper() can't ignore differences
-    //      macOS:  CFStringCompare() considers differences
+    /* Unicode normal forms:
+          Windows: CompareString() already ignores NFD/NFC differences: nice...
+          Linux:  g_unichar_toupper() can't ignore differences
+          macOS:  CFStringCompare() considers differences */
 
     const Zstring& lhsNorm = getUnicodeNormalForm(lhs);
     const Zstring& rhsNorm = getUnicodeNormalForm(rhs);
diff --git a/zen/zstring.h b/zen/zstring.h
index 1afebe58..b8dfb9a3 100644
--- a/zen/zstring.h
+++ b/zen/zstring.h
@@ -138,7 +138,7 @@ Zstring getFileExtension(const Zstring& filePath)
 //common unicode characters
 const wchar_t EN_DASH = L'\u2013';
 const wchar_t EM_DASH = L'\u2014';
-const wchar_t* const SPACED_DASH = L" \u2014 "; //using 'EM DASH'
+    const wchar_t* const SPACED_DASH = L" \u2014 "; //using 'EM DASH'
 const wchar_t LTR_MARK = L'\u200E'; //UTF-8: E2 80 8E
 const wchar_t* const ELLIPSIS = L"\u2026"; //"..."
 const wchar_t MULT_SIGN = L'\u00D7'; //fancy "x"
@@ -151,11 +151,4 @@ const wchar_t BIDI_POP_DIR_ISOLATE    = L'\u2069'; //UTF-8: E2 81 A9 => not work
 const wchar_t BIDI_DIR_EMBEDDING_RTL  = L'\u202B'; //UTF-8: E2 80 AB => not working on Win 10
 const wchar_t BIDI_POP_DIR_FORMATTING = L'\u202C'; //UTF-8: E2 80 AC => not working on Win 10
 
-
-
-
-//---------------------------------------------------------------------------
-//ZEN macro consistency checks:
-
-
 #endif //ZSTRING_H_73425873425789