--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Hex.h	Wed Apr 20 02:26:44 2022 +0200
@@ -0,0 +1,85 @@
+/**
+ * Relational pipes
+ * Copyright © 2022 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <iomanip>
+#include <iostream>
+#include <sstream>
+#include <vector>
+#include <stdexcept>
+
+namespace relpipe {
+namespace in {
+namespace posixmq {
+
+class Hex {
+private:
+
+	Hex() {
+	}
+
+	static char fromHex(wchar_t ch) {
+		if (L'0' <= ch && ch <= L'9') return ch - L'0';
+		else if (L'a' <= ch && ch <= L'f') return ch - L'a' + 10;
+		else throw std::invalid_argument("Unable to decode hexadeximal string.");
+	}
+
+public:
+
+	static std::stringstream fromHex(const std::wstring& hex) {
+		std::stringstream octets;
+
+		char octet = 0;
+
+		for (size_t i = 0, limit = hex.size(); i < limit; i++) {
+			if (i % 2 == 0) {
+				octet = fromHex(hex[i]) << 4;
+			} else {
+				octet += fromHex(hex[i]);
+				octets.put(octet);
+			}
+		}
+
+		return octets;
+	}
+
+	static std::wstring toHex(const std::string& octets) {
+		std::wstring_convert < codecvt_utf8<wchar_t>> convertor; // TODO: do not create converter each time
+		std::stringstream hex;
+		hex << std::hex << std::setfill('0') << std::hex;
+		for (size_t i = 0, size = octets.size(); i < size; i++) hex << std::setw(2) << (0xff & octets[i]);
+		return convertor.from_bytes(hex.str());
+	}
+
+	static std::wstring toTxt(const std::string& octets, bool* validEncoding = nullptr) {
+		std::wstring_convert < codecvt_utf8<wchar_t>> convertor; // TODO: do not create converter each time
+		try {
+			if (validEncoding) *validEncoding = true;
+			// TODO: use encoding from the HTTP response headers instead of the constant one?
+			return convertor.from_bytes(octets);
+		} catch (...) {
+			if (validEncoding) *validEncoding = false;
+			std::stringstream filtered;
+			for (char ch : octets) filtered << (ch >= ' ' && ch < 127 ? ch : '.');
+			return convertor.from_bytes(filtered.str());
+		}
+	}
+};
+
+}
+}
+}

--- a/src/PosixMQCommand.cpp	Sat Mar 05 19:41:05 2022 +0100
+++ b/src/PosixMQCommand.cpp	Wed Apr 20 02:26:44 2022 +0200
@@ -34,6 +34,7 @@
 
 #include "PosixMQCommand.h"
 #include "PosixMQ.h"
+#include "Hex.h"
 
 using namespace std;
 using namespace relpipe::cli;
@@ -57,13 +58,9 @@
 	for (int i = configuration.messageCount; i > 0; i--) {
 		std::string message = mq->receive();
 
-		std::stringstream hex;
-		hex << std::hex << std::setfill('0');
-		for (uint8_t b : message) hex << std::setw(2) << (int) b;
-
 		writer->writeAttribute(configuration.queue);
-		writer->writeAttribute(convertor.from_bytes(message)); // Show at least ASCII characters + ... if UTF-8 decoding fails
-		writer->writeAttribute(convertor.from_bytes(hex.str()));
+		writer->writeAttribute(Hex::toTxt(message));
+		writer->writeAttribute(Hex::toHex(message));
 	}
 
 }