test/nbt_size_helpers: Implement tests for valid input

I stumbled over this when writing the unit test. Previously, it would return
an error code but explicitly mark it as not being an error. This was intended
behavior but I decided to change it because I didn’t anticipate it when writing
the test.

Technically `ErrorOr<T>` can be used to pass any message alongside `T`,
but practically, it is reasonable to assume that the error code is
`ErrorCodes::SUCCESS` when `isError` is false. Therefore, this feature
should be really only used in the weirdest edge cases - if at all.
Even then, it is most likely still preferable to flag it as an error and
just hand the resulting `T` back using the long constructor
`ErrorOr<T>(bool, uint8_t, T)`.

src/lib/cli.cpp

@@ -258,5 +258,66 @@ namespace CLI {
         // argument is not present, but this is not an error -> false, NOT_PRESENT, ""
         else return ErrorOr<std::string>(false, ErrorCodes::NOT_PRESENT, std::string(""));
     }
-    //std::string ArgumentsParser::getUsage();
+
+    std::string ArgumentsParser::getUsage(){
+        std::string usageString = "";
+        if (this->description != "") {
+            usageString += "Help: " + this->programName + "\n\n\t" + this->description + "\n\n";
+        }
+        usageString += "Usage: " + this->programName + " ";
+
+        if(!this->flagsByShortName.empty()){
+            usageString += "[-";
+        }
+
+        for(const auto& [key, value]: this->flagsByShortName){
+            usageString.push_back(key);
+        }
+
+        if(!this->flagsByShortName.empty()){
+            usageString += "] ";
+        }
+
+        for(const auto& [key, value]: this->optionsByShortName){
+            usageString += "[-";
+            usageString.push_back(key);
+            usageString += " " + value->placeholder + "] ";
+        }
+
+        for(const auto& argument: this->arguments){
+            usageString += argument.placeholder + " ";
+        }
+
+        usageString.push_back('\n');
+
+        if(!this->flagsByShortName.empty()){
+            usageString += "\nFlags:\n";
+
+            for(const auto& [key, value]: this->flagsByShortName){
+                usageString += "\t-";
+                usageString.push_back(key);
+                usageString += ", --" + value->longName + "\n\t\t" + value->description + "\n";
+            }
+        }
+
+        if(!this->optionsByShortName.empty()){
+            usageString += "\nOptions:\n";
+
+            for(const auto& [key, value]: this->optionsByShortName){
+                usageString += "\t-";
+                usageString.push_back(key);
+                usageString += " " + value->placeholder + ", --" + value->longName + "=" + value->placeholder + "\n\t\t" + value->description + "\n";
+            }
+        }
+
+        if(!this->arguments.empty()){
+            usageString += "\nArguments:\n";
+
+            for(const auto& argument: this->arguments){
+                usageString += "\t" + argument.placeholder + "\n\t\t" + argument.description + "\n";
+            }
+        }
+
+        return usageString;
+    }
 }

src/lib/cli.h++

@@ -1,94 +0,0 @@
-// Copyright 2022, FOSS-VG Developers and Contributers
-//
-// This program is free software: you can redistribute it and/or modify it
-// under the terms of the GNU Affero General Public License as published
-// by the Free Software Foundation, version 3.
-//
-// 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 Affero General Public License for more details.
-//
-// You should have received a copy of the GNU Affero General Public License
-// version 3 along with this program.
-// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
-
-#pragma once
-
-#include <string>
-#include <vector>
-#include <map>
-
-#include "error.hpp"
-
-namespace CLI {
-
-    struct Flag {
-        char shortName;
-        std::string longName;
-        // used for automatic usage generation
-        std::string description;
-
-        bool present;
-
-        Flag();
-        Flag(char shortName, std::string longName, std::string description);
-    };
-
-    struct Option {
-        char shortName;
-        std::string longName;
-        // used for automatic usage generation
-        std::string description;
-        std::string placeholder; // the "COUNT" in "ping [-c <COUNT>] <HOST>"
-
-        bool present;
-        std::string value;
-
-        Option();
-        Option(char shortName, std::string longName, std::string placeholder, std::string description);
-    };
-
-    struct Argument {
-        // used for automatic usage generation
-        std::string description;
-        std::string placeholder; // the "HOST" in "ping [-c <COUNT>] <HOST>"
-
-        bool present;
-        std::string value;
-
-        Argument();
-        Argument(std::string placeholder, std::string description);
-    };
-
-    class ArgumentsParser {
-        private:
-            std::map<char, Flag*> flagsByShortName;
-            std::map<std::string, Flag*> flagsByLongName;
-            std::map<char, Option*> optionsByShortName;
-            std::map<std::string, Option*> optionsByLongName;
-            std::vector<Argument> arguments;
-            std::string description;
-            std::string additionalInfo;
-
-        public:
-            std::string programName;
-            bool wrongUsage;
-            std::vector<std::string> wrongUsageMessages;
-
-            // using int here bc that's how main() is defined
-            ArgumentsParser(int argc, const char* const argv[], std::vector<Flag> flags, std::vector<Option> options, std::vector<Argument> arguments);
-            ArgumentsParser(int argc, const char* const argv[], std::vector<Flag> flags, std::vector<Option> options, std::vector<Argument> arguments, std::string description);
-            ArgumentsParser(int argc, const char* const argv[], std::vector<Flag> flags, std::vector<Option> options, std::vector<Argument> arguments, std::string description, std::string additionalInfo);
-            ~ArgumentsParser();
-
-            ErrorOr<bool> getFlag(char shortName);
-            ErrorOr<bool> getFlag(std::string longName);
-            ErrorOr<std::string> getArgument(std::vector<CLI::Argument>::size_type position);
-            ErrorOr<std::string> getOption(char shortName);
-            ErrorOr<std::string> getOption(std::string longName);
-
-            std::string getUsage();
-    };
-
-}

src/test/cli_argument_parser.cpp

@@ -23,7 +23,7 @@
 
 int main() {
     std::cout << "################################################################################" << std::endl;
-    std::cout << "CLI argument parser tests" << std::endl;
+    std::cout << "CLI argument parsing tests" << std::endl;
     std::cout << "################################################################################" << std::endl;
 
     // Valid parameter test ############################################
@@ -636,5 +636,115 @@ int main() {
     delete[] tooManyArgumentsTestParameterList;
     std::cout << "Passed too many arguments test." << std::endl;
 
+    std::cout << "################################################################################" << std::endl;
+    std::cout << "CLI argument parser help tests" << std::endl;
+    std::cout << "################################################################################" << std::endl;
+
+    // normal usage with all types of CLI input ########################
+    std::vector<CLI::Flag> helpTestFlags;
+    helpTestFlags.push_back(CLI::Flag('a', "apple", "throws an apple on Newton's head."));
+    helpTestFlags.push_back(CLI::Flag('y', "yapple", "throws an yapple on Newton's head."));
+
+    std::vector<CLI::Option> helpTestOptions;
+    helpTestOptions.push_back(CLI::Option('b', "banana", "BANANA", "smack someone with a ripe banana."));
+    helpTestOptions.push_back(CLI::Option('c', "corn", "CORNHUBBBBB", "visit cornhub."));
+
+    std::vector<CLI::Argument> helpTestArguments;
+    helpTestArguments.push_back(CLI::Argument("WASH", "Number of times to wash my shark."));
+    helpTestArguments.push_back(CLI::Argument("SHAKE", "Number of times to shake fist at cloud."));
+
+    const char** helpTestCommand = new const char*[1];
+    helpTestCommand[0] = "universecreator";
+    CLI::ArgumentsParser helpTestParser = CLI::ArgumentsParser(1, helpTestCommand, helpTestFlags, helpTestOptions, helpTestArguments, "Create a universe with a banana and an apple.");
+
+    ASSERT(helpTestParser.getUsage() == "Help: universecreator\n\n\tCreate a universe with a banana and an apple.\n\nUsage: universecreator [-ay] [-b BANANA] [-c CORNHUBBBBB] WASH SHAKE \n\nFlags:\n\t-a, --apple\n\t\tthrows an apple on Newton's head.\n\t-y, --yapple\n\t\tthrows an yapple on Newton's head.\n\nOptions:\n\t-b BANANA, --banana=BANANA\n\t\tsmack someone with a ripe banana.\n\t-c CORNHUBBBBB, --corn=CORNHUBBBBB\n\t\tvisit cornhub.\n\nArguments:\n\tWASH\n\t\tNumber of times to wash my shark.\n\tSHAKE\n\t\tNumber of times to shake fist at cloud.\n");
+    std::cout << "Passed normal usage test." << std::endl;
+
+    // no description ##################################################
+    std::vector<CLI::Flag> usageOnlyTestFlags;
+    usageOnlyTestFlags.push_back(CLI::Flag('a', "apple", "throws an apple on Newton's head."));
+    usageOnlyTestFlags.push_back(CLI::Flag('y', "yapple", "throws an yapple on Newton's head."));
+
+    std::vector<CLI::Option> usageOnlyTestOptions;
+    usageOnlyTestOptions.push_back(CLI::Option('b', "banana", "BANANA", "smack someone with a ripe banana."));
+    usageOnlyTestOptions.push_back(CLI::Option('c', "corn", "CORNHUBBBBB", "visit cornhub."));
+
+    std::vector<CLI::Argument> usageOnlyTestArguments;
+    usageOnlyTestArguments.push_back(CLI::Argument("WASH", "Number of times to wash my shark."));
+    usageOnlyTestArguments.push_back(CLI::Argument("SHAKE", "Number of times to shake fist at cloud."));
+
+    const char** usageOnlyTestCommand = new const char*[1];
+    usageOnlyTestCommand[0] = "universecreator";
+    CLI::ArgumentsParser usageOnlyTestParser = CLI::ArgumentsParser(1, usageOnlyTestCommand, usageOnlyTestFlags, usageOnlyTestOptions, usageOnlyTestArguments);
+
+    ASSERT(usageOnlyTestParser.getUsage() == "Usage: universecreator [-ay] [-b BANANA] [-c CORNHUBBBBB] WASH SHAKE \n\nFlags:\n\t-a, --apple\n\t\tthrows an apple on Newton's head.\n\t-y, --yapple\n\t\tthrows an yapple on Newton's head.\n\nOptions:\n\t-b BANANA, --banana=BANANA\n\t\tsmack someone with a ripe banana.\n\t-c CORNHUBBBBB, --corn=CORNHUBBBBB\n\t\tvisit cornhub.\n\nArguments:\n\tWASH\n\t\tNumber of times to wash my shark.\n\tSHAKE\n\t\tNumber of times to shake fist at cloud.\n");
+    std::cout << "Passed normal usage without description test." << std::endl;
+
+    // no flags ########################################################
+    std::vector<CLI::Flag> noFlagsFlags;
+
+    std::vector<CLI::Option> noFlagsOptions;
+    noFlagsOptions.push_back(CLI::Option('b', "banana", "BANANA", "smack someone with a ripe banana."));
+    noFlagsOptions.push_back(CLI::Option('c', "corn", "CORNHUBBBBB", "visit cornhub."));
+
+    std::vector<CLI::Argument> noFlagsArguments;
+    noFlagsArguments.push_back(CLI::Argument("WASH", "Number of times to wash my shark."));
+    noFlagsArguments.push_back(CLI::Argument("SHAKE", "Number of times to shake fist at cloud."));
+
+    const char** noFlagsCommand = new const char*[1];
+    noFlagsCommand[0] = "universecreator";
+    CLI::ArgumentsParser noFlagsParser = CLI::ArgumentsParser(1, noFlagsCommand, noFlagsFlags, noFlagsOptions, noFlagsArguments, "Create a universe with a banana and an apple.");
+
+    ASSERT(noFlagsParser.getUsage() == "Help: universecreator\n\n\tCreate a universe with a banana and an apple.\n\nUsage: universecreator [-b BANANA] [-c CORNHUBBBBB] WASH SHAKE \n\nOptions:\n\t-b BANANA, --banana=BANANA\n\t\tsmack someone with a ripe banana.\n\t-c CORNHUBBBBB, --corn=CORNHUBBBBB\n\t\tvisit cornhub.\n\nArguments:\n\tWASH\n\t\tNumber of times to wash my shark.\n\tSHAKE\n\t\tNumber of times to shake fist at cloud.\n");
+
+    // no options ######################################################
+    std::vector<CLI::Flag> noOptionsFlags;
+    noOptionsFlags.push_back(CLI::Flag('a', "apple", "throws an apple on Newton's head."));
+    noOptionsFlags.push_back(CLI::Flag('y', "yapple", "throws an yapple on Newton's head."));
+
+    std::vector<CLI::Option> noOptionsOptions;
+
+    std::vector<CLI::Argument> noOptionsArguments;
+    noOptionsArguments.push_back(CLI::Argument("WASH", "Number of times to wash my shark."));
+    noOptionsArguments.push_back(CLI::Argument("SHAKE", "Number of times to shake fist at cloud."));
+
+    const char** noOptionsCommand = new const char*[1];
+    noOptionsCommand[0] = "universecreator";
+    CLI::ArgumentsParser noOptionsParser = CLI::ArgumentsParser(1, noOptionsCommand, noOptionsFlags, noOptionsOptions, noOptionsArguments, "Create a universe with a banana and an apple.");
+
+    ASSERT(noOptionsParser.getUsage() == "Help: universecreator\n\n\tCreate a universe with a banana and an apple.\n\nUsage: universecreator [-ay] WASH SHAKE \n\nFlags:\n\t-a, --apple\n\t\tthrows an apple on Newton's head.\n\t-y, --yapple\n\t\tthrows an yapple on Newton's head.\n\nArguments:\n\tWASH\n\t\tNumber of times to wash my shark.\n\tSHAKE\n\t\tNumber of times to shake fist at cloud.\n");
+
+    // no arguments ####################################################
+    std::vector<CLI::Flag> noArgumentsFlags;
+    noArgumentsFlags.push_back(CLI::Flag('a', "apple", "throws an apple on Newton's head."));
+    noArgumentsFlags.push_back(CLI::Flag('y', "yapple", "throws an yapple on Newton's head."));
+
+    std::vector<CLI::Option> noArgumentsOptions;
+    noArgumentsOptions.push_back(CLI::Option('b', "banana", "BANANA", "smack someone with a ripe banana."));
+    noArgumentsOptions.push_back(CLI::Option('c', "corn", "CORNHUBBBBB", "visit cornhub."));
+
+    std::vector<CLI::Argument> noArgumentsArguments;
+
+    const char** noArgumentsCommand = new const char*[1];
+    noArgumentsCommand[0] = "universecreator";
+    CLI::ArgumentsParser noArgumentsParser = CLI::ArgumentsParser(1, noArgumentsCommand, noArgumentsFlags, noArgumentsOptions, noArgumentsArguments, "Create a universe with a banana and an apple.");
+
+    ASSERT(noArgumentsParser.getUsage() == "Help: universecreator\n\n\tCreate a universe with a banana and an apple.\n\nUsage: universecreator [-ay] [-b BANANA] [-c CORNHUBBBBB] \n\nFlags:\n\t-a, --apple\n\t\tthrows an apple on Newton's head.\n\t-y, --yapple\n\t\tthrows an yapple on Newton's head.\n\nOptions:\n\t-b BANANA, --banana=BANANA\n\t\tsmack someone with a ripe banana.\n\t-c CORNHUBBBBB, --corn=CORNHUBBBBB\n\t\tvisit cornhub.\n");
+    std::cout << "Passed absent section usage test." << std::endl;
+
+    // no CLI input ####################################################
+    std::vector<CLI::Flag> noCLIFlags;
+
+    std::vector<CLI::Option> noCLIOptions;
+
+    std::vector<CLI::Argument> noCLIArguments;
+
+    const char** noCLICommand = new const char*[1];
+    noCLICommand[0] = "universecreator";
+    CLI::ArgumentsParser noCLIParser = CLI::ArgumentsParser(1, noCLICommand, noCLIFlags, noCLIOptions, noCLIArguments, "Create a universe with a banana and an apple.");
+
+    ASSERT(noCLIParser.getUsage() == "Help: universecreator\n\n\tCreate a universe with a banana and an apple.\n\nUsage: universecreator \n");
+    std::cout << "Passed no CLI input usage test." << std::endl;
+
     return 0;
 }

src/tools/hexnet.cpp

@@ -19,6 +19,7 @@
 #include <cstdint>
 #include <cctype>
 #include <sockpp/tcp_acceptor.h>
+#include <sockpp/tcp6_acceptor.h>
 #include <thread>
 #include <mutex>
 #include <csignal>
@@ -40,8 +41,11 @@ int64_t mtu = 1500;
 std::string host;
 in_port_t port;
 sockpp::tcp_socket* tcpSocket;
+sockpp::tcp6_socket* tcp6Socket;
 sockpp::tcp_acceptor tcpAcceptor;
+sockpp::tcp6_acceptor tcp6Acceptor;
 std::mutex tcpSocketMutex;
+std::mutex tcp6SocketMutex;
 std::mutex consoleMutex;
 // used for coordinated graceful exit across threads
 bool exitProgram = false;
@@ -50,12 +54,20 @@ void signalHandler(int signal) {
     exitProgram = true;
     // if still waiting for incoming connection, stop waiting
     tcpAcceptor.shutdown();
+    tcp6Acceptor.shutdown();
     // tell sockpp to close TCP socket if open because it blocks when trying
     // to read and there is no data
-    if (*tcpSocket) {
+
+    if (tcpSocket != nullptr && *tcpSocket) {
         // Intentionally not using the mutex here
+        std::cout << "test\n";
         tcpSocket->shutdown(SHUT_RD);
     }
+
+    if (tcp6Socket != nullptr && *tcp6Socket) {
+        // Intentionally not using the mutex here
+        tcp6Socket->shutdown(SHUT_RD);
+    }
     //TODO: figure out if - and how - this applies to UDP
 
     // Priority is to finish up all unfinished business that can be finished up.
@@ -64,32 +76,71 @@ void signalHandler(int signal) {
     consoleMutex.lock();
     std::cerr << "Received signal " << signal << ", shutting down." << std::endl;
     consoleMutex.unlock();
+    std::exit(signal);
 }
 
 void readFromTCPSocket(sockpp::tcp_socket* socket, int64_t mtu) {
-        ssize_t numBytes;
+    ssize_t numBytes;
-        uint8_t buffer[mtu];
+    uint8_t buffer[mtu];
-        tcpSocketMutex.lock();
+    tcpSocketMutex.lock();
-        while (!exitProgram && (numBytes = socket->read(buffer, sizeof(buffer))) > 0) {
+    while (!exitProgram && (numBytes = socket->read(buffer, sizeof(buffer))) > 0) {
-            tcpSocketMutex.unlock();
-            consoleMutex.lock();
-            for (ssize_t i=0; i<numBytes; i++) {
-                std::cout << std::hex << std::setfill('0') << std::setw(2) << (short) buffer[i];
-            }
-            std::cout.flush();
-            consoleMutex.unlock();
-            tcpSocketMutex.lock();
-        }
         tcpSocketMutex.unlock();
         consoleMutex.lock();
-        std::cerr << std::endl << "Connection closed." << std::endl;
+        for (ssize_t i=0; i<numBytes; i++) {
+            std::cout << std::hex << std::setfill('0') << std::setw(2) << (short) buffer[i];
+        }
+        std::cout.flush();
         consoleMutex.unlock();
+        tcpSocketMutex.lock();
+    }
+    tcpSocketMutex.unlock();
+    consoleMutex.lock();
+    std::cerr << std::endl << "Connection closed." << std::endl;
+    consoleMutex.unlock();
+}
+
+void readFromTCP6Socket(sockpp::tcp6_socket* socket, int64_t mtu){
+    ssize_t numBytes;
+    uint8_t buffer[mtu];
+    tcp6SocketMutex.lock();
+    while (!exitProgram && (numBytes = socket->read(buffer, sizeof(buffer))) > 0) {
+        tcp6SocketMutex.unlock();
+        consoleMutex.lock();
+        for (ssize_t i=0; i<numBytes; i++) {
+            std::cout << std::hex << std::setfill('0') << std::setw(2) << (short) buffer[i];
+        }
+        std::cout.flush();
+        consoleMutex.unlock();
+        tcp6SocketMutex.lock();
+    }
+    tcp6SocketMutex.unlock();
+    consoleMutex.lock();
+    std::cerr << std::endl << "Connection closed." << std::endl;
+    consoleMutex.unlock();
+}
+
+void writeToTCPSocket(sockpp::tcp_socket* socket){
+    while (!exitProgram) {
+       //TODO: Implement locking/unlocking/threading shenanigans
+    }
+    consoleMutex.lock();
+    std::cerr << std::endl << "Connection closed." << std::endl;
+    consoleMutex.unlock();
+}
+
+void writeToTCP6Socket(sockpp::tcp6_socket* socket){
+    while (!exitProgram) {
+       //TODO: Implement locking/unlocking/threading shenanigans
+    }
+    consoleMutex.lock();
+    std::cerr << std::endl << "Connection closed." << std::endl;
+    consoleMutex.unlock();
 }
 
 int main(int argc, char* argv[]){
 
-    signal(SIGINT, signalHandler);
+    std::signal(SIGINT, signalHandler);
-    signal(SIGTERM, signalHandler);
+    std::signal(SIGTERM, signalHandler);
 
     std::vector<CLI::Flag> flags;
     flags.push_back(CLI::Flag('4', "ipv4", "use IPv4, defaults to both when -4 and -6 are omitted, otherwise uses what is specified"));
@@ -98,84 +149,142 @@ int main(int argc, char* argv[]){
     flags.push_back(CLI::Flag('u', "udp", "use UDP, defaults to both when -t and -u are omitted, otherwise uses what is specified"));
     flags.push_back(CLI::Flag('n', "no-color", "disable coloring the output (intended for terminals that don't work well with color escape sequences)"));
     flags.push_back(CLI::Flag('e', "echo-back", "echo input back to stdout"));
+    flags.push_back(CLI::Flag('h', "help", "print this information and exit"));
+    flags.push_back(CLI::Flag('l', "license", "print license information and exit"));
 
     std::vector<CLI::Option> options;
     options.push_back(CLI::Option('c', "connect", "HOST", "connect to HOST, listen for incoming connections if omitted"));
     options.push_back(CLI::Option('m', "mtu-optimize", "MTU", "Optimize for a specific maximum transfer unit by reading MTU bytes at a time."));
     options.push_back(CLI::Option(
-        'p', "print-prefixes", "TCPv4i:UDPv4i:TCPv6i:UDPv6i:TCPv4o:UDPv4o:TCPv6o:UDPv6o",
+        'p', "print-prefixes", "TCPin:UDPin:TCPout:UDPout",
-        "override default prefixes for output (defaults to spaces + coloring the output or \"t4:u4:t6:u6:T4:U4:T6:U6\" in no-color mode)"
+        "override default prefixes for output (defaults to spaces + coloring the output or \"t:u:T:U\" in no-color mode)"
     ));
     options.push_back(CLI::Option(
-        'i', "input-prefixes", "TCP:UDP:IPv4:IPv6",
+        'i', "input-prefixes", "TCP:UDP",
-        "override default prefixes for input (defaults to \"t:u:4:6\")"
+        "override default prefixes for input (defaults to \"t:u\")"
     ));
 
     std::vector<CLI::Argument> arguments;
     arguments.push_back(CLI::Argument("PORT", "the port to use"));
 
-    CLI::ArgumentsParser cliParser = CLI::ArgumentsParser(argc, argv, flags, options, arguments);
+    CLI::ArgumentsParser cliParser = CLI::ArgumentsParser(argc, argv, flags, options, arguments, "Arbitrary tcp/udp connections in hex format.");
+
+    if (cliParser.getFlag("help").value){
+        std::cout << cliParser.getUsage() << std::endl;
+        return EXIT_SUCCESS;
+    }
+    if (cliParser.getFlag("license").value){
+        std::cout
+            << "Copyright 2022, FOSS-VG Developers and Contributers\n"
+            << "\n"
+            << "Hexnet is part of the FOSS-VG development tool suite.\n"
+            << "\n"
+            << "This program is free software: you can redistribute it and/or modify it\n"
+            << "under the terms of the GNU Affero General Public License as published\n"
+            << "by the Free Software Foundation, version 3.\n"
+            << "\n"
+            << "This program is distributed in the hope that it will be useful,\n"
+            << "but WITHOUT ANY WARRANTY; without even the implied\n"
+            << "warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
+            << "See the GNU Affero General Public License for more details.\n"
+            << "\n"
+            << "You should have received a copy of the GNU Affero General Public License\n"
+            << "version 3 along with this program.\n"
+            << "If not, see https://www.gnu.org/licenses/agpl-3.0.en.html"
+            << std::endl;
+        return EXIT_SUCCESS;
+    }
 
     if (cliParser.wrongUsage) {
-        //TODO: spit out usage information generated by the parser
+        std::cout << cliParser.getUsage() << std::endl;
         return EXIT_USAGE;
     }
-    if (cliParser.getFlag('4').value || cliParser.getFlag('6').value) {
+    if (cliParser.getFlag("ipv4").value || cliParser.getFlag("ipv6").value) {
-        ipv4 = cliParser.getFlag('4').value;
+        ipv4 = cliParser.getFlag("ipv4").value;
-        ipv6 = cliParser.getFlag('6').value;
+        ipv6 = cliParser.getFlag("ipv4").value;
     }
-    if (cliParser.getFlag('t').value || cliParser.getFlag('u').value) {
+    if (cliParser.getFlag("tcp").value || cliParser.getFlag("udp").value) {
-        tcp = cliParser.getFlag('t').value;
+        tcp = cliParser.getFlag("tcp").value;
-        udp = cliParser.getFlag('u').value;
+        udp = cliParser.getFlag("udp").value;
     }
     if (cliParser.getOption('c').errorCode == ErrorCodes::NOT_PRESENT) {
         listenMode = true;
     }
-    if (cliParser.getOption('m').errorCode == ErrorCodes::SUCCESS) {
+    if (cliParser.getOption("mtu-optimize").errorCode == ErrorCodes::SUCCESS) {
-        mtu = std::stol(cliParser.getOption('m').value);
+        mtu = std::stol(cliParser.getOption("mtu-optimize").value);
     }
-    host = cliParser.getOption('c').value;
+    host = cliParser.getOption("connect").value;
     //FIXME: use a function that returns a fixed-width data type instead,
     //       ensure that the given value is a valid port
     port = (in_port_t) std::stoi(cliParser.getArgument(0).value);
 
     if (listenMode) {
-        if (ipv6) {
-            std::cerr << "IPv6 support is not implented yet." << std::endl;
-            return EXIT_UNIMPLEMENTED;
-        }
         if (udp) {
             std::cerr << "UDP support is not implemented yet." << std::endl;
             return EXIT_UNIMPLEMENTED;
         }
-        std::cerr << "Listening on port " << port << "." << std::endl;
 
-        sockpp::socket_initializer socketInitializer;
+        if (ipv6) {
-        tcpAcceptor = sockpp::tcp_acceptor(port);
+            //std::cerr << "IPv6 support is not implented yet." << std::endl;
+            //return EXIT_UNIMPLEMENTED;
+            std::cerr << "Listening on port " << port << "." << std::endl;
+            sockpp::socket_initializer socketInitializer;
+            tcp6Acceptor = sockpp::tcp6_acceptor(port);
 
-        if (!tcpAcceptor) {
+            if(!tcp6Acceptor){
-            std::cerr << "Error while creating TCP acceptor: " << tcpAcceptor.last_error_str() << std::endl;
+                std::cerr << "Error while creating TCP6 acceptor: " << tcp6Acceptor.last_error_str() << std::endl;
-            return EXIT_RUNTIME;
+                return EXIT_RUNTIME;
+            }
+
+            sockpp::inet6_address peer;
+            tcp6Socket = new sockpp::tcp6_socket();
+            *tcp6Socket = tcp6Acceptor.accept(&peer);
+
+            std::cerr << "Incoming connection from " << peer << std::endl;
+
+            if (!(*tcp6Socket)) {
+                std::cerr << "Error on incoming connection: " << tcp6Acceptor.last_error_str() << std::endl;
+                delete tcp6Socket;
+                return EXIT_RUNTIME;
+            }
+
+            std::thread threadReadFromTCP6 = std::thread(readFromTCP6Socket, tcp6Socket, mtu);
+            threadReadFromTCP6.join();
+
+            delete tcp6Socket;
+            return EXIT_SUCCESS;
         }
 
-        sockpp::inet_address peer;
+        if(ipv4){
-        tcpSocket = new sockpp::tcp_socket();
+            std::cerr << "Listening on port " << port << "." << std::endl;
-        *tcpSocket = tcpAcceptor.accept(&peer);
 
-        std::cerr << "Incoming connection from " << peer << std::endl;
+            sockpp::socket_initializer socketInitializer;
+            tcpAcceptor = sockpp::tcp_acceptor(port);
+
+            if (!tcpAcceptor) {
+                std::cerr << "Error while creating TCP acceptor: " << tcpAcceptor.last_error_str() << std::endl;
+                return EXIT_RUNTIME;
+            }
+
+            sockpp::inet_address peer;
+            tcpSocket = new sockpp::tcp_socket();
+            *tcpSocket = tcpAcceptor.accept(&peer);
+
+            std::cerr << "Incoming connection from " << peer << std::endl;
+
+            if (!(*tcpSocket)) {
+                std::cerr << "Error on incoming connection: " << tcpAcceptor.last_error_str() << std::endl;
+                delete tcpSocket;
+                return EXIT_RUNTIME;
+            }
+
+            std::thread threadReadFromTCP = std::thread(readFromTCPSocket, tcpSocket, mtu);
+            threadReadFromTCP.join();
 
-        if (!(*tcpSocket)) {
-            std::cerr << "Error on incoming connection: " << tcpAcceptor.last_error_str() << std::endl;
             delete tcpSocket;
-            return EXIT_RUNTIME;
+            return EXIT_SUCCESS;
         }
 
-        std::thread threadReadTCP = std::thread(readFromTCPSocket, tcpSocket, mtu);
-        threadReadTCP.join();
-
-        delete tcpSocket;
-        return EXIT_SUCCESS;
-
     } else {
         std::cerr << "Client mode is not implemented yet." << std::endl;
         return EXIT_UNIMPLEMENTED;