restructured the program

CMakeLists.txt

@@ -9,23 +9,50 @@ set(CMAKE_CXX_STANDARD_REQUIRED ON)
 find_package(PkgConfig REQUIRED)
 pkg_check_modules(MPG123 REQUIRED libmpg123)
 pkg_check_modules(PORTAUDIO REQUIRED portaudio-2.0)
+pkg_check_modules(OpenSSL REQUIRED openssl)
 
 
 add_executable(M2-PT-DRP
         source/main.cpp
-        source/Client.cpp
-        source/Client.hpp
-        source/Server.cpp
-        source/Server.hpp
         source/packets/AudioPacket.hpp
         source/utils/audio.cpp
         source/utils/audio.hpp
+        source/EventManager.cpp
+        source/EventManager.hpp
+        source/packets/base/GenericPacket.hpp
+        source/events/types.hpp
+        source/packets/base/GenericPacket.cpp
+        source/Peer.hpp
+        source/utils/StatList.cpp
+        source/utils/StatList.hpp
+        source/events/base/BaseEvent.hpp
+        source/events/base/BaseEvent.hpp
+        source/events/audio/AudioPacketsComparator.cpp
+        source/events/audio/AudioPacketsComparator.hpp
+        source/events/audio/AudioEvent.hpp
+        source/events/audio/AudioEvent.cpp
+        source/events/pong/PongEvent.cpp
+        source/events/pong/PongEvent.hpp
+        source/events/search/SearchEvent.cpp
+        source/events/search/SearchEvent.hpp
+        source/events/info/InfoEvent.cpp
+        source/events/info/InfoEvent.hpp
+        source/tasks/types.hpp
+        source/tasks/base/BaseTask.hpp
+        source/tasks/server/ServerTask.cpp
+        source/tasks/server/ServerTask.hpp
+        source/tasks/undefined/UndefinedTask.cpp
+        source/tasks/undefined/UndefinedTask.hpp
+        source/tasks/client/ClientTask.cpp
+        source/tasks/client/ClientTask.hpp
 )
 target_include_directories(M2-PT-DRP PRIVATE
         ${MPG123_INCLUDE_DIRS}
         ${PORTAUDIO_INCLUDE_DIRS}
+        ${OPENSSL_INCLUDE_DIRS}
 )
 target_link_libraries(M2-PT-DRP PRIVATE
         ${MPG123_LIBRARIES}
         ${PORTAUDIO_LIBRARIES}
+        ${OPENSSL_LIBRARIES}
 )

source/Client.hpp

@@ -1,65 +0,0 @@
-#pragma once
-
-
-#include <condition_variable>
-#include <mutex>
-#include <portaudio.h>
-#include <queue>
-#include <thread>
-
-#include "packets/AudioPacket.hpp"
-
-
-// TODO(Faraphel): should be moved somewhere else
-struct AudioPacketsComparator {
-    bool operator() (const AudioPacket &a, const AudioPacket &b) const {
-        return a.timePlay > b.timePlay;
-    }
-};
-
-
-/**
- * the audio Client.
- * Receive audio packets and play them at a specific time.
- */
-class Client {
-public:
-    explicit Client();
-    ~Client();
-
-    /**
-     * Update the current audio stream
-     * @param channels the number of channels
-     * @param sampleFormat the sample format type
-     * @param sampleRate the audio rate
-     */
-    void updateStream(int channels, std::uint32_t sampleFormat, double sampleRate);
-
-    /**
-     * Indefinitely receive and play audio data.
-     */
-    void loop();
-
-private:
-    /**
-     * Indefinitely receive audio data.
-     */
-    void loopReceiver();
-
-    /**
-     * Indefinitely play audio data.
-     */
-    void loopPlayer();
-
-    PaStream* stream;
-    int streamChannels;
-    std::uint32_t streamSampleFormat;
-    double streamRate;
-    std::priority_queue<AudioPacket, std::vector<AudioPacket>, AudioPacketsComparator> audioQueue;
-
-    std::mutex audioMutex;
-    std::unique_lock<std::mutex> audioLock;
-    std::condition_variable audioCondition;
-    std::thread receiverThread;
-    std::thread playerThread;
-};

source/EventManager.cpp

@@ -0,0 +1,183 @@
+#include "EventManager.hpp"
+
+#include <algorithm>
+#include <stdexcept>
+#include <cstdint>
+#include <cstring>
+#include <iostream>
+#include <map>
+#include <netdb.h>
+#include <ostream>
+#include <thread>
+#include <sys/socket.h>
+
+#include "Peer.hpp"
+#include "events/types.hpp"
+#include "events/audio/AudioEvent.hpp"
+#include "events/info/InfoEvent.hpp"
+#include "events/pong/PongEvent.hpp"
+#include "events/search/SearchEvent.hpp"
+#include "packets/base/GenericPacket.hpp"
+#include "tasks/client/ClientTask.hpp"
+#include "tasks/server/ServerTask.hpp"
+#include "tasks/undefined/UndefinedTask.hpp"
+
+
+EventManager::EventManager() {
+    this->channel = 0;
+    this->server = nullptr;
+    this->status = drp::task::TaskType::UNDEFINED;
+
+    // register the different events type
+    this->eventRegistry = {
+        {drp::event::EventType::PONG, std::make_shared<drp::event::PongEvent>()},
+        {drp::event::EventType::SEARCH, std::make_shared<drp::event::SearchEvent>()},
+        {drp::event::EventType::INFO, std::make_shared<drp::event::InfoEvent>()},
+        {drp::event::EventType::AUDIO, std::make_shared<drp::event::AudioEvent>()},
+    };
+
+    // register the different tasks type
+    this->taskRegistry = {
+        {drp::task::TaskType::UNDEFINED, std::make_shared<drp::task::UndefinedTask>()},
+        {drp::task::TaskType::CLIENT, std::make_shared<drp::task::ClientTask>()},
+        {drp::task::TaskType::SERVER, std::make_shared<drp::task::ServerTask>()},
+    };
+
+    // hints for the communication
+    // TODO: should be merged with the two others addressHints
+    addrinfo addressHints {};
+    addressHints.ai_family = AF_INET;  // TODO: AF_INET6
+    addressHints.ai_socktype = SOCK_DGRAM;
+    addressHints.ai_protocol = IPPROTO_UDP;
+
+    // create the client socket
+    this->eventSocket = socket(
+        addressHints.ai_family,
+        addressHints.ai_socktype,
+        addressHints.ai_protocol
+    );
+
+    if (this->eventSocket < 0)
+        throw std::runtime_error("[Receiver] Could not create the socket: " + std::string(strerror(errno)));
+}
+
+
+void EventManager::loop() {
+    // run an event receiver and sender
+    this->senderThread = std::thread(&EventManager::loopSender, this);
+    this->receiverThread = std::thread(&EventManager::loopReceiver, this);
+
+    this->senderThread.join();
+    this->receiverThread.join();
+}
+
+
+void EventManager::loopSender() {
+    addrinfo* destinationInfo;
+
+    addrinfo addressHints {};
+    addressHints.ai_family = AF_INET;  // TODO: AF_INET6
+    addressHints.ai_socktype = SOCK_DGRAM;
+    addressHints.ai_protocol = IPPROTO_UDP;
+
+    // get the information for the broadcast local-link address
+    // TODO(Faraphel): ip / port as argument ?
+    if(const int error = getaddrinfo(
+        "localhost",  // TODO: ff02::1
+        "5650",
+        &addressHints,
+        &destinationInfo
+    ) != 0)
+        throw std::runtime_error("[Sender] Could not get the address: " + std::string(gai_strerror(error)));
+
+
+    while (true) {
+        // get the corresponding task class
+        std::shared_ptr<drp::task::BaseTask> task;
+        try {
+            task = this->taskRegistry.at(this->status);
+        } catch (const std::out_of_range& exception) {
+            std::cerr << "Unsupported status." << std::endl;
+            continue;
+        }
+
+        // ask the task class to handle the task
+        task->handle();
+
+        // wait a second
+        // TODO(Faraphel): might be moved to the tasks directly ? what if they want a lower cooldown ?
+        std::this_thread::sleep_for(std::chrono::seconds(1));
+    }
+
+    // free the address
+    freeaddrinfo(destinationInfo);
+}
+
+
+void EventManager::loopReceiver() {
+    // prepare space for the sender address
+    sockaddr_storage senderAddress {};
+    socklen_t senderAddressLength = sizeof(senderAddress);
+    drp::packet::GenericPacket packet {};
+    drp::packet::GenericPacketContent packetContent {};
+
+    addrinfo addressHints {};
+    addressHints.ai_family = AF_INET;  // TODO: AF_INET6
+    addressHints.ai_socktype = SOCK_DGRAM;
+    addressHints.ai_protocol = IPPROTO_UDP;
+
+    // TODO(Faraphel): port as argument
+    addrinfo* senderInfo;
+    if(getaddrinfo(
+        nullptr,  // hostname
+        "5650",  // port
+        &addressHints,
+        &senderInfo
+    ) != 0)
+        throw std::runtime_error("[Receiver] Could not get the address: " + std::string(gai_strerror(errno)));
+
+    // bind the socket to the address
+    if (bind(
+        this->eventSocket,
+        senderInfo->ai_addr,
+        senderInfo->ai_addrlen
+    ) < 0)
+        throw std::runtime_error("[Receiver] Could not bind to the address: " + std::string(strerror(errno)));
+
+    // free the sender address
+    freeaddrinfo(senderInfo);
+
+    // client loop
+    while (true) {
+        // receive new data
+        const ssize_t size = recvfrom(
+            this->eventSocket,
+            &packet,
+            sizeof(packet),
+            0,
+            reinterpret_cast<sockaddr*>(&senderAddress),
+            &senderAddressLength
+        );
+        if (size == -1)
+            throw std::runtime_error("[Receiver] Could not receive the packet: " + std::string(strerror(errno)));
+
+        // if the packet channel is neither 0 (all) nor the current one, ignore it
+        if (packet.channel != 0 && packet.channel != this->channel)
+            continue;
+
+        // decrypt the packet
+        packetContent = packet.getContent();
+
+        // get the corresponding event class
+        std::shared_ptr<drp::event::BaseEvent> event;
+        try {
+            event = this->eventRegistry.at(static_cast<drp::event::EventType>(packetContent.eventType));
+        } catch (const std::out_of_range& exception) {
+            std::cerr << "Unsupported event type." << std::endl;
+            continue;
+        }
+
+        // ask the event class to handle the event
+        event->handle(packetContent);
+    }
+}

source/EventManager.hpp

@@ -0,0 +1,38 @@
+#pragma once
+
+#include <cstdint>
+#include <map>
+#include <netdb.h>
+#include <thread>
+
+#include "Peer.hpp"
+#include "events/types.hpp"
+#include "events/base/BaseEvent.hpp"
+#include "tasks/types.hpp"
+#include "tasks/base/BaseTask.hpp"
+#include "utils/StatList.hpp"
+
+
+class EventManager {
+public:
+    EventManager();
+
+    void loop();
+    void loopSender();
+    void loopReceiver();
+
+private:
+    std::thread senderThread;  /// the thread sending communication
+    std::thread receiverThread;  /// the thread receiving communication
+
+    std::map<drp::event::EventType, std::shared_ptr<drp::event::BaseEvent>> eventRegistry;  /// hold the event to call depending on the event type
+    std::map<drp::task::TaskType, std::shared_ptr<drp::task::BaseTask>> taskRegistry;  /// hold the task to call depending on the server status
+
+    StatList<std::shared_ptr<Peer>> peers;  /// list of peers found
+    std::shared_ptr<Peer> server;  /// the peer used as a server
+
+    int eventSocket;  /// the socket used to communicate
+    drp::task::TaskType status;  /// our current status
+
+    std::uint8_t channel;  /// the packet channel currently used
+};

source/Peer.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <sys/socket.h>
+
+#include "tasks/types.hpp"
+
+
+struct Peer {
+    // communication
+    sockaddr address;
+    socklen_t addressLength;
+
+    // information
+    drp::task::TaskType status;
+};

source/events/README.md

@@ -0,0 +1 @@
+This directory contains the code describing how to react to a specific event.

source/events/audio/AudioEvent.cpp

@@ -1,28 +1,41 @@
-#include "Client.hpp"
+#include "AudioEvent.hpp"
 
-#include <cstring>
 #include <iostream>
-#include <list>
-#include <map>
-#include <netdb.h>
-#include <queue>
-#include <stdexcept>
-#include <thread>
-#include <sys/socket.h>
-
-#include "packets/AudioPacket.hpp"
+#include <bits/unique_lock.h>
 
 
-Client::Client() {
+namespace drp::event {
+
+
+AudioEvent::AudioEvent() {
     this->stream = nullptr;
     this->audioLock = std::unique_lock(this->audioMutex);
 
     this->streamChannels = 0;
     this->streamSampleFormat = 0;
     this->streamRate = 0;
+
+    // start a thread for the player
+    this->playerThread = std::thread(&AudioEvent::loopPlay, this);
 }
 
-void Client::updateStream(const int channels, const std::uint32_t sampleFormat, const double sampleRate) {
+AudioEvent::~AudioEvent() {
+    // stop any currently playing audio
+    Pa_StopStream(this->stream);
+    // close the audio stream
+    if (const PaError error = Pa_CloseStream(this->stream))
+        std::cerr << "[Client] Could not close the stream: " << std::string(Pa_GetErrorText(error)) << std::endl;
+}
+
+
+void AudioEvent::handle(const packet::GenericPacketContent& content) {
+    this->audioQueue.push(static_cast<packet::AudioPacket>(content));
+    // notify that a new audio chunk is available
+    this->audioCondition.notify_one();
+}
+
+
+void AudioEvent::updateAudioStream(const int channels, const std::uint32_t sampleFormat, const double sampleRate) {
     // check if any information changed. If no, ignore this
     if (
         this->streamChannels == channels &&
@@ -54,92 +67,8 @@ void Client::updateStream(const int channels, const std::uint32_t sampleFormat,
     this->streamRate = sampleRate;
 }
 
-Client::~Client() {
-    // stop any currently playing audio
-    Pa_StopStream(this->stream);
-    // close the audio stream
-    if (const PaError error = Pa_CloseStream(this->stream))
-        std::cerr << "[Client] Could not close the stream: " << std::string(Pa_GetErrorText(error)) << std::endl;
-}
 
-
-void Client::loop() {
-    // run an audio receiver alongside an audio player
-    this->receiverThread = std::thread(&Client::loopReceiver, this);
-    this->playerThread = std::thread(&Client::loopPlayer, this);
-
-    this->receiverThread.join();
-    this->playerThread.join();
-}
-
-void Client::loopReceiver() {
-    // create the socket
-    const int clientSocket = socket(
-        AF_INET6,
-        SOCK_DGRAM,
-        0
-    );
-    if (clientSocket < 0)
-        throw std::runtime_error("[Client] Could not create the socket: " + std::string(gai_strerror(errno)));
-
-    // get the broadcast address
-    addrinfo serverHints = {};
-    serverHints.ai_family = AF_INET6;
-    serverHints.ai_socktype = SOCK_DGRAM;
-    serverHints.ai_protocol = IPPROTO_UDP;
-
-    // TODO(Faraphel): port as argument
-    addrinfo *serverInfo;
-    if(getaddrinfo(
-        nullptr,  // hostname
-        "5650",  // our port
-        &serverHints,
-        &serverInfo
-    ) != 0)
-        throw std::runtime_error("[Client] Could not get the address: " + std::string(gai_strerror(errno)));
-
-    // bind the socket to the address
-    if (bind(
-        clientSocket,
-        serverInfo->ai_addr,
-        serverInfo->ai_addrlen
-    ) < 0)
-        throw std::runtime_error("[Client] Could not bind to the address: " + std::string(gai_strerror(errno)));
-
-    // free the server address
-    freeaddrinfo(serverInfo);
-
-    // prepare space for the server address
-    sockaddr_storage serverAddress {};
-    socklen_t serverAddressLength;
-    // prepare space for the received audio
-    AudioPacket audioPacket;
-
-    // receive new audio data
-    while (true) {
-        // receive new audio data
-        const ssize_t size = recvfrom(
-            clientSocket,
-            &audioPacket,
-            sizeof(audioPacket),
-        0,
-            reinterpret_cast<sockaddr *>(&serverAddress),
-            &serverAddressLength
-        );
-        if (size == -1) {
-            std::cerr << "[Client] Could not receive from the socket: " << gai_strerror(errno) << std::endl;
-            continue;
-        }
-
-        // save the audio data into the queue for the player
-        std::cout << "[Client] Received: " << size << " bytes" << std::endl;
-        this->audioQueue.push(audioPacket);
-        // notify that a new audio chunk is available
-        this->audioCondition.notify_one();
-    }
-}
-
-void Client::loopPlayer() {
+void AudioEvent::loopPlay() {
     while (true) {
         // wait for a new element in the audio queue
         this->audioCondition.wait(
@@ -150,7 +79,7 @@ void Client::loopPlayer() {
         const auto audioPacket = this->audioQueue.top();
 
         // update the stream with the new audio settings
-        this->updateStream(
+        this->updateAudioStream(
             audioPacket.channels,
             audioPacket.sampleFormat,
             audioPacket.sampleRate
@@ -179,7 +108,7 @@ void Client::loopPlayer() {
         switch (error) {
             // success
             case paNoError:
-            // the output might be very slightly underflowed,
+            // the output might be very slightly underflown,
             // causing a very small period where no noise will be played.
             case paOutputUnderflowed:
                 break;
@@ -192,3 +121,6 @@ void Client::loopPlayer() {
         this->audioQueue.pop();
     }
 }
+
+
+}

source/events/audio/AudioEvent.hpp

@@ -0,0 +1,40 @@
+#pragma once
+#include <condition_variable>
+#include <portaudio.h>
+#include <queue>
+#include <bits/std_mutex.h>
+#include <bits/unique_lock.h>
+
+#include "AudioPacketsComparator.hpp"
+#include "../base/BaseEvent.hpp"
+
+
+namespace drp::event {
+
+
+class AudioEvent : public BaseEvent {
+public:
+    AudioEvent();
+    ~AudioEvent() override;
+
+    void updateAudioStream(int channels, std::uint32_t sampleFormat, double sampleRate);
+    void loopPlay();
+
+    void handle(const packet::GenericPacketContent& content) override;
+
+private:
+    std::thread playerThread;
+
+    PaStream* stream;
+    int streamChannels;
+    std::uint32_t streamSampleFormat;
+    double streamRate;
+    std::priority_queue<packet::AudioPacket, std::vector<packet::AudioPacket>, AudioPacketsComparator> audioQueue;
+
+    std::mutex audioMutex;
+    std::unique_lock<std::mutex> audioLock;
+    std::condition_variable audioCondition;
+};
+
+
+}

source/events/audio/AudioPacketsComparator.cpp

@@ -0,0 +1,12 @@
+#include "AudioPacketsComparator.hpp"
+
+
+namespace drp::event {
+
+
+bool AudioPacketsComparator::operator()(const packet::AudioPacket& a, const packet::AudioPacket& b) const {
+    return a.timePlay > b.timePlay;
+}
+
+
+}

source/events/audio/AudioPacketsComparator.hpp

@@ -0,0 +1,14 @@
+#pragma once
+
+#include "../../packets/audio/AudioPacket.hpp"
+
+
+namespace drp::event {
+
+
+struct AudioPacketsComparator {
+    bool operator() (const packet::AudioPacket& a, const packet::AudioPacket& b) const;
+};
+
+
+}

source/events/base/BaseEvent.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+#include "../../packets/base/GenericPacket.hpp"
+
+
+namespace drp::event {
+
+
+class BaseEvent {
+public:
+    virtual ~BaseEvent() = default;
+    virtual void handle(const packet::GenericPacketContent& content) = 0;
+};
+
+
+}

source/events/info/InfoEvent.cpp

@@ -0,0 +1,21 @@
+#include "InfoEvent.hpp"
+
+#include <sys/socket.h>
+
+#include "../../tasks/types.hpp"
+
+namespace drp::event {
+
+
+void InfoEvent::handle(const packet::GenericPacketContent& content) {
+    Peer peer {};
+    peer.address = *reinterpret_cast<sockaddr*>(&senderAddress);
+    peer.addressLength = senderAddressLength;
+    peer.status = task::TaskType::UNDEFINED;
+
+    // save it in the peers list
+    this->peers.push_back(peer);
+}
+
+
+}

source/events/info/InfoEvent.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "../base/BaseEvent.hpp"
+
+
+namespace drp::event {
+
+
+class InfoEvent : public BaseEvent {
+public:
+    void handle(const packet::GenericPacketContent& content) override;
+};
+
+
+}

source/events/pong/PongEvent.cpp

@@ -0,0 +1,14 @@
+#include "PongEvent.hpp"
+
+#include <iostream>
+
+
+namespace drp::event {
+
+
+void PongEvent::handle(const packet::GenericPacketContent& content) {
+    std::cout << "[Receiver] Pong." << std::endl;
+}
+
+
+}

source/events/pong/PongEvent.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "../base/BaseEvent.hpp"
+
+
+namespace drp::event {
+
+
+class PongEvent : public BaseEvent {
+public:
+    void handle(const packet::GenericPacketContent& content) override;
+};
+
+
+}

source/events/search/SearchEvent.cpp

@@ -0,0 +1,45 @@
+#include "SearchEvent.hpp"
+
+#include <cerrno>
+#include <sys/socket.h>
+#include <cstring>
+#include <iostream>
+#include <ostream>
+
+#include "../../tasks/types.hpp"
+#include "../../events/types.hpp"
+
+
+namespace drp {
+
+
+void event::SearchEvent::handle(const packet::GenericPacketContent& content) {
+    packet::GenericPacket packet {};
+    packet::GenericPacketContent packetContent {};
+
+    Information information {};
+    information.status = task::TaskType::UNDEFINED;
+
+    packet.channel = 0;
+    packet.securityMode = static_cast<std::uint8_t>(packet::SecurityMode::PLAIN);
+
+    packetContent.eventType = static_cast<std::uint8_t>(EventType::INFO);
+    std::memcpy(&packetContent.data, &information, sizeof(Information));
+    packet.setContent(packetContent);
+
+    if (sendto(
+        clientSocket,
+        &packet,
+        sizeof(packet),
+        0,
+        serverAddress,
+        serverAddressLength
+    ) == -1)
+        std::cerr << "[Receiver] Could not send information: " << strerror(errno) << std::endl;
+
+    std::cout << "[Receiver] Sent information." << std::endl;
+}
+
+
+
+}

source/events/search/SearchEvent.hpp

@@ -0,0 +1,14 @@
+#pragma once
+#include "../base/BaseEvent.hpp"
+
+
+namespace drp::event {
+
+
+class SearchEvent : public BaseEvent {
+public:
+    void handle(const packet::GenericPacketContent& content) override;
+};
+
+
+}

source/events/types.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+
+namespace drp::event {
+
+
+enum class EventType {
+    // debug
+    PING = 0x00,  // simple ping
+    PONG = 0x01,  // ping response
+
+    // protocol
+    SEARCH = 0x10,  // search for devices
+    INFO = 0x011,  // information about ourselves
+
+    // security
+    RSA_PUBLIC_KEY = 0x20,  // sharing asymmetric public key
+    AES_SECRET_KEY = 0x21,  // sharing symmetric private key
+
+    // functionality
+    AUDIO = 0x30,  // play a sound at a given time
+};
+
+
+}

source/main.cpp

@@ -1,10 +1,7 @@
 #include <mpg123.h>
 #include <portaudio.h>
 #include <stdexcept>
-#include <thread>
-
-#include "Client.hpp"
-#include "Server.hpp"
+#include "EventManager.hpp"
 
 
 int main(int argc, char* argv[]) {
@@ -18,15 +15,8 @@ int main(int argc, char* argv[]) {
     if (Pa_Initialize() != paNoError)
         throw std::runtime_error("Could not initialize PortAudio.");
 
-    // start the client and server
-    Server server;
-    Client client;
-
-    std::thread serverThread(&Server::loop, &server);
-    std::thread clientThread(&Client::loop, &client);
-
-    serverThread.join();
-    clientThread.join();
+    EventManager eventManager;
+    eventManager.loop();
 
     // terminate the libraries
     Pa_Terminate();

source/packets/audio/AudioPacket.hpp

@@ -4,15 +4,21 @@
 #include <cstdint>
 
 
+namespace drp::packet {
+
+
 struct AudioPacket {
     // scheduling
     // TODO(Faraphel): use a more "fixed" size format ?
     std::chrono::time_point<std::chrono::high_resolution_clock> timePlay;
     // audio settings
-    std::uint8_t channels;
-    std::uint32_t sampleFormat;
-    std::uint32_t sampleRate;
+    std::uint8_t channels {};
+    std::uint32_t sampleFormat {};
+    std::uint32_t sampleRate {};
     // content
-    std::uint16_t contentSize;
-    std::array<std::uint8_t, 65280> content;
+    std::uint16_t contentSize {};
+    std::array<std::uint8_t, 65280> content {};
 };
+
+
+}

source/packets/base/GenericPacket.cpp

@@ -0,0 +1,90 @@
+#include "GenericPacket.hpp"
+
+#include <stdexcept>
+
+
+namespace drp::packet {
+
+
+/*
+GenericPacketContent decryptPacketContentAes(const GenericPacket& packet) {
+    GenericPacketContent decryptedPacketContent {};
+
+    const auto& [key, iv] = keysAes[serverAddress];
+
+    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
+    if (EVP_DecryptInit_ex(
+        ctx,
+        EVP_aes_256_cbc(),
+        nullptr,
+        key,
+        iv
+    ) != 1)
+        throw std::runtime_error("[Client] Could not initialize the EVP_CIPHER_CTX.");
+
+    int packetContentLength;
+
+    if (EVP_DecryptUpdate(
+        ctx,
+        reinterpret_cast<std::uint8_t*>(&decryptedPacketContent),
+        &packetContentLength,
+        reinterpret_cast<const std::uint8_t*>(&packet.encryptedContent),
+        sizeof(packet)
+    ) != 1)
+        throw std::runtime_error("[Client] Could not encrypt the plaintext.");
+
+    if (EVP_DecryptFinal_ex(
+        ctx,
+        reinterpret_cast<std::uint8_t*>(&decryptedPacketContent + packetContentLength),
+        &packetContentLength
+    ) != 1)
+        throw std::runtime_error("[Client] Could not decrypt the final plaintext.");
+
+    EVP_CIPHER_CTX_free(ctx);
+
+    return decryptedPacketContent;
+}
+*/
+
+
+GenericPacketContent GenericPacket::getContent() const {
+    // TODO(Faraphel): implement RSA and AES
+    //   additional "context" argument to hold cryptographic keys ?
+
+    switch (static_cast<SecurityMode>(this->securityMode)) {
+        case SecurityMode::PLAIN:
+            return this->_content;
+
+        case SecurityMode::AES:
+            // return decryptPacketContentAes(packet);
+            throw std::runtime_error("Not implemented.");
+
+        case SecurityMode::RSA:
+            throw std::runtime_error("Not implemented.");
+
+        default:
+            throw std::runtime_error("Unsupported security mode.");
+    }
+}
+
+
+void GenericPacket::setContent(const GenericPacketContent &content) {
+    // TODO(Faraphel): implement RSA and AES
+    switch (static_cast<SecurityMode>(this->securityMode)) {
+        case SecurityMode::PLAIN:
+            this->_content = content;
+            return;
+
+        case SecurityMode::AES:
+            throw std::runtime_error("Not implemented.");
+
+        case SecurityMode::RSA:
+            throw std::runtime_error("Not implemented.");
+
+        default:
+            throw std::runtime_error("Unsupported security mode.");
+    }
+}
+
+
+}

source/packets/base/GenericPacket.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+#include <array>
+#include <cstdint>
+
+
+namespace drp::packet {
+
+
+enum class SecurityMode {
+    PLAIN = 0x00,
+    AES = 0x01,
+    RSA = 0x02,
+};
+
+
+// the maximum data length
+// a packet can't be larger than 65565 (uint16 max)
+// reserve some space for metadata and settings
+constexpr std::uint16_t dataLength = 65504;
+
+/**
+ * The content of a generic packet.
+ * @param eventType the type of event that the packet want to trigger.
+ * @param data the data of the event.
+ */
+struct GenericPacketContent {
+    std::uint8_t eventType;
+    std::array<std::uint8_t, dataLength> data;
+};
+
+/**
+ * A generic packet that can be transmitted through the network.
+ * @param channel the channel of the packet. Two system can be created inside a same network by using different
+ * channels value. "0" is used for "broadcast" message across networks.
+ * @param securityMode the type of security used in the packet.
+ * @param _content the content of the packet. It is encrypted accordingly to the securityMode.
+ */
+struct GenericPacket {
+    std::uint8_t channel;
+    std::uint8_t securityMode;
+    GenericPacketContent _content;
+
+    [[nodiscard]] GenericPacketContent getContent() const;
+    void setContent(const GenericPacketContent& content);
+};
+
+
+}

source/tasks/README.md

@@ -0,0 +1 @@
+This directory contains the code describing how should the machine send event to its peers.

source/tasks/base/BaseTask.hpp

@@ -0,0 +1,14 @@
+#pragma once
+
+namespace drp::task {
+
+
+class BaseTask {
+public:
+    virtual ~BaseTask() = default;
+
+    virtual void handle() = 0;
+};
+
+
+}

source/tasks/client/ClientTask.cpp

@@ -0,0 +1,14 @@
+#include "ClientTask.hpp"
+
+namespace drp::task {
+
+
+void ClientTask::handle() {
+    // TODO(Faraphel): connect to an ntp server
+
+    // TODO(Faraphel): check if the server is still reachable.
+    //   if connection lost, go back to undefined mode.
+}
+
+
+}

source/tasks/client/ClientTask.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "../base/BaseTask.hpp"
+
+
+namespace drp::task {
+
+
+class ClientTask : public BaseTask {
+public:
+    void handle() override;
+};
+
+
+}

source/tasks/server/ServerTask.cpp

@@ -1,4 +1,4 @@
-#include "Server.hpp"
+#include "ServerTask.hpp"
 
 #include <iostream>
 #include <cstdint>
@@ -10,11 +10,11 @@
 #include <sys/socket.h>
 #include <vector>
 
-#include "packets/AudioPacket.hpp"
-#include "utils/audio.hpp"
+
+namespace drp::task {
 
 
-Server::Server() {
+ServerTask::ServerTask() {
     this->channels = 0;
     this->encoding = 0;
     this->sampleRate = 0;
@@ -44,13 +44,15 @@ Server::Server() {
         throw std::runtime_error("[Server] Could not get the format of the file.");
 }
 
-Server::~Server() {
+ServerTask::~ServerTask() {
     // delete the mpg123 handle
     mpg123_close(this->mpgHandle);
     mpg123_delete(this->mpgHandle);
 }
 
-void Server::loop() const {
+void ServerTask::loop() const {
+    // TODO(Faraphel): create a chrony server
+
     // get the broadcast address
     addrinfo broadcastHints {};
     broadcastHints.ai_family = AF_INET6;
@@ -125,3 +127,6 @@ void Server::loop() const {
     // free the server address
     freeaddrinfo(broadcastInfo);
 }
+
+
+}

source/tasks/server/ServerTask.hpp

@@ -2,19 +2,19 @@
 #include <mpg123.h>
 
 
+namespace drp::task {
+
+
 /**
  * the audio Server.
  * Read and broadcast audio data.
  */
-class Server {
+class ServerTask : public BaseTask {
 public:
-    explicit Server();
-    ~Server();
+    explicit ServerTask();
+    ~ServerTask();
 
-    /**
-     * Indefinitely read and broadcast audio data.
-     */
-    void loop() const;
+    void handle() override;
 
 private:
     mpg123_handle* mpgHandle;
@@ -23,3 +23,6 @@ private:
     int channels;
     int encoding;
 };
+
+
+}

source/tasks/types.hpp

@@ -0,0 +1,14 @@
+#pragma once
+
+
+namespace drp::task {
+
+
+enum class TaskType {
+    UNDEFINED = 0x00,
+    CLIENT = 0x01,
+    SERVER = 0x02,
+};
+
+
+}

source/tasks/undefined/UndefinedTask.cpp

@@ -0,0 +1,71 @@
+#include "UndefinedTask.hpp"
+#include "../types.hpp"
+
+#include <chrono>
+#include <cstring>
+#include <iostream>
+#include <sys/socket.h>
+
+#include "../../events/types.hpp"
+#include "../../packets/base/GenericPacket.hpp"
+
+
+namespace drp::task {
+
+
+void UndefinedTask::handle() {
+    // TODO(Faraphel): If .status is UNDEFINED, look for a server.
+    //  if alone, become a server (if can emit).
+    //  if everyone is UNKNOWN, elect a server (easiest to join / highest mac address, etc...)
+    //  if a server is found, become a client.
+
+    // check if no more peers have been found.
+    if (
+        std::chrono::high_resolution_clock::now() - this->peers.getModificationTime() >
+        std::chrono::milliseconds(5000)
+    ) {
+        // verify if there are peers
+        if (this->peers.empty()) {
+            // if we are alone, become the server
+            // TODO(Faraphel): only apply if we are capable of emitting !
+            this->status = TaskType::SERVER;
+            return;
+        }
+
+        // search for a server in the peers
+        const auto& server = std::find_if(
+            this->peers.begin(),
+            this->peers.end(),
+            [&](const Peer& peer) { return peer.status == TaskType::SERVER; }
+        );
+        if (server != this->peers.end()) {
+            // if a server have been found, use it
+            this->server = *server;
+            this->status = TaskType::CLIENT;
+            return;
+        }
+
+        // TODO(Faraphel): elect a server among those capable of emitting.
+        //   send the average ping of all the machine in the information packet ?
+        //   add an additionnal random value if equals ?
+    }
+
+    // prepare a search message
+    packet.channel = 0;
+    packet.securityMode = static_cast<std::uint8_t>(packet::SecurityMode::PLAIN);
+    packet._content.eventType = static_cast<std::uint8_t>(event::EventType::SEARCH);
+
+    // send the search message
+    if (sendto(
+        this->eventSocket,
+        &packet,
+        sizeof(packet),
+        0,
+        destinationInfo->ai_addr,
+        destinationInfo->ai_addrlen
+    ) == -1)
+        std::cerr << "[Sender] Could not send search event: " << strerror(errno) << std::endl;
+}
+
+
+}

source/tasks/undefined/UndefinedTask.hpp

@@ -0,0 +1,13 @@
+#pragma once
+#include "../base/BaseTask.hpp"
+
+
+namespace drp::task {
+
+
+class UndefinedTask : public BaseTask {
+    void handle() override;
+};
+
+
+}

source/utils/StatList.cpp

@@ -0,0 +1,30 @@
+#include "StatList.hpp"
+
+
+template<class T>
+StatList<T>::StatList() {
+    this->updateModificationTime();
+}
+
+template<class T>
+void StatList<T>::push_back(const T &value) {
+    std::list<T>::push_back(value);
+    this->updateModificationTime();
+}
+
+template<class T>
+void StatList<T>::pop_back() {
+    std::list<T>::pop_back();
+    this->updateModificationTime();
+}
+
+template<class T>
+std::chrono::time_point<std::chrono::high_resolution_clock> StatList<T>::getModificationTime() const {
+    return this->modificationTime;
+}
+
+
+template<class T>
+void StatList<T>::updateModificationTime() {
+    this->modificationTime = std::chrono::high_resolution_clock::now();
+}

source/utils/StatList.hpp

@@ -0,0 +1,24 @@
+#pragma once
+
+#include <chrono>
+#include <list>
+
+
+/**
+ * A simple list with additional stat data, such as the date of the latest modification
+ * @tparam T the type of elements in the list
+ */
+template<class T>
+class StatList : public std::list<T> {
+public:
+    StatList();
+
+    void push_back(const T& value);
+    void pop_back();
+
+    [[nodiscard]] std::chrono::time_point<std::chrono::high_resolution_clock> getModificationTime() const;
+
+private:
+    void updateModificationTime();
+    std::chrono::time_point<std::chrono::high_resolution_clock> modificationTime;
+};