Cosmetic changes

CMakeLists.txt

@@ -54,7 +54,6 @@ target_link_libraries(playground PRIVATE spdlog::spdlog)
 #
 
 
-
 enable_testing()
 
 add_executable(

src/main.cpp

@@ -1,12 +1,15 @@
-#include "tcp.hpp"
-#include <cstddef>
+// Library includes
 #include <spdlog/spdlog.h>
 
+// Project includes
+#include "tcp.hpp"
+
+
 int main() {
     spdlog::set_level(spdlog::level::debug);
 
-    tcp::NonBlockingServer server{{.port = 65432}};
-    if (auto res = server.start_listening(); !res) {
+    tcp::NonBlockingServer server{};
+    if (auto res = server.start_listening(65432); !res) {
         spdlog::error("Failed to start server: {}", res.error());
         return 1;
     }
@@ -47,6 +50,6 @@ int main() {
             spdlog::info("Sent {} bytes", sendRes.value());
         }
 
-        server.disconnect();
+        server.disconnect_from_client();
     }
 }

src/tcp.cpp

@@ -1,18 +1,12 @@
 #include "tcp.hpp"
 
+// C stdlib includes
 #include <arpa/inet.h>
-#include <cerrno>
-#include <cstdint>
-#include <expected>
 #include <fcntl.h>
 #include <netdb.h>
-#include <netinet/in.h>
-#include <netinet/tcp.h>
-#include <poll.h>
-#include <span>
+
+// Library includes
 #include <spdlog/spdlog.h>
-#include <sys/socket.h>
-#include <sys/types.h>
 
 
 namespace {
@@ -36,7 +30,7 @@ std::expected<sockaddr_in, int> resolve_remote_address(const char* host,
     return address;
 }
 
-inline auto get_local_address(uint16_t port) -> sockaddr_in {
+inline sockaddr_in get_local_address(uint16_t port) {
     sockaddr_in address{};
     address.sin_addr.s_addr = htonl(INADDR_ANY);
     address.sin_family      = AF_INET;
@@ -45,7 +39,6 @@ inline auto get_local_address(uint16_t port) -> sockaddr_in {
 }
 
 
-
 } // namespace
 
 
@@ -59,43 +52,49 @@ namespace tcp {
 //
 
 
-NonBlockingServer::NonBlockingServer(ServerSettings settings)
-    : m_settings{settings}, m_serverAddress(get_local_address(settings.port)) {
-}
-
 NonBlockingServer::~NonBlockingServer() {
     close_client_socket();
     close_server_socket();
 }
 
-std::expected<void, int> NonBlockingServer::start_listening() {
+///
+/// @details Calling this repeatedly closes the previous socket and creates a
+/// new one.
+///
+std::expected<void, int> NonBlockingServer::start_listening(uint16_t port) {
     /// Create socket
 
     close_server_socket();
-    if (auto res = create_socket(); !res) {
+    if (auto res = create_server_socket(); !res) {
         return std::unexpected{res.error()};
     }
 
     /// Bin socket and start listening
 
-    if (::bind(m_serverSocket, (struct sockaddr*)&m_serverAddress,
-               sizeof(m_serverAddress)) != 0) {
+    const struct sockaddr_in serverAddress = get_local_address(port);
+
+    if (::bind(m_serverSocket, (struct sockaddr*)&serverAddress,
+               sizeof(serverAddress)) != 0) {
         spdlog::error("tcp::NonBlockingServer: bind() failed with errno={}",
                       errno);
-        close(m_serverSocket);
+        close_server_socket();
         return std::unexpected{errno};
     };
 
     if (::listen(m_serverSocket, 1) != 0) {
         spdlog::error("tcp::NonBlockingServer: listen() failed with errno={}",
                       errno);
-        close(m_serverSocket);
+        close_server_socket();
         return std::unexpected{errno};
     }
 
     return {};
 }
 
+void NonBlockingServer::stop_listening() {
+    close_server_socket();
+}
+
 bool NonBlockingServer::next_client_available() {
     int ret = poll(&m_serverPfdIn, 1, 0);
     if (ret < 0) {
@@ -108,10 +107,12 @@ bool NonBlockingServer::next_client_available() {
 }
 
 [[nodiscard]] std::expected<void, int> NonBlockingServer::accept_next_client() {
-    disconnect();
+    disconnect_from_client();
+
+    socklen_t clientAddrLen = sizeof(m_clientAddress);
 
     int result = ::accept(m_serverSocket, (struct sockaddr*)&m_clientAddress,
-                          &m_clientAddrLen);
+                          &clientAddrLen);
     if (result < 0) return std::unexpected{errno};
 
     m_clientSocket   = result;
@@ -119,16 +120,13 @@ bool NonBlockingServer::next_client_available() {
 
     return {};
 }
-void NonBlockingServer::disconnect() {
+
+void NonBlockingServer::disconnect_from_client() {
     close_client_socket();
 }
 
-// TODO: Do we need this?
-// bool NonBlockingServer::socket_closed() const {
-// }
-
 [[nodiscard]] std::expected<std::array<char, 16>, int>
-NonBlockingServer::get_client_ip_as_string() const {
+NonBlockingServer::get_client_ip_as_string() {
     std::array<char, 16> addrStr;
 
     if (inet_ntop(AF_INET, &((struct sockaddr_in*)&m_clientAddress)->sin_addr,
@@ -143,34 +141,7 @@ NonBlockingServer::get_client_ip_as_string() const {
     //     return std::unexpected{errno};
     // }
 
-    return {addrStr};
-}
-
-[[nodiscard]] std::expected<int, int>
-NonBlockingServer::send(std::span<const std::byte> data) const {
-    const int bytesWritten =
-        ::send(m_clientSocket, (const char*)data.data(), data.size(), 0);
-
-    if (bytesWritten <= 0) {
-        spdlog::error("tcp::NonBlockingServer: send() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-
-    return bytesWritten;
-}
-
-[[nodiscard]] std::expected<int, int>
-NonBlockingServer::recv(std::span<std::byte> buffer) const {
-    const int bytesReceived =
-        ::recv(m_clientSocket, (char*)buffer.data(), buffer.size(), 0);
-
-    if (bytesReceived < 0) {
-        spdlog::error("tcp::NonBlockingServer: recv() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-    return {bytesReceived};
+    return addrStr;
 }
 
 bool NonBlockingServer::data_available() {
@@ -184,11 +155,40 @@ bool NonBlockingServer::data_available() {
     return (m_clientPfdIn.revents & POLLIN);
 }
 
-[[nodiscard]] std::expected<void, int> NonBlockingServer::create_socket() {
+[[nodiscard]] std::expected<int, int>
+NonBlockingServer::send(std::span<const std::byte> data) {
+    const int bytesWritten =
+        ::send(m_clientSocket, (const char*)data.data(), data.size(), 0);
+
+    if (bytesWritten <= 0) {
+        spdlog::error("tcp::NonBlockingServer: send() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    return bytesWritten;
+}
+
+[[nodiscard]] std::expected<int, int>
+NonBlockingServer::recv(std::span<std::byte> buffer) {
+    const int bytesReceived =
+        ::recv(m_clientSocket, (char*)buffer.data(), buffer.size(), 0);
+
+    if (bytesReceived < 0) {
+        spdlog::error("tcp::NonBlockingServer: recv() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+    return {bytesReceived};
+}
+
+[[nodiscard]] std::expected<void, int>
+NonBlockingServer::create_server_socket() {
     m_serverSocket = socket(AF_INET, SOCK_STREAM, 0);
     if (m_serverSocket < 1) {
         spdlog::error("tcp::NonBlockingServer: socket() failed with errno={}",
                       errno);
+        close_server_socket();
         return std::unexpected{errno};
     }
 
@@ -264,7 +264,7 @@ NonBlockingClient::~NonBlockingClient() {
 }
 
 [[nodiscard]] std::expected<void, int>
-NonBlockingClient::connect(HostString host, uint16_t port) {
+NonBlockingClient::connect(const HostString& host, uint16_t port) {
     /// Resolve host
 
     auto addrRes = resolve_remote_address(host.data(), port);
@@ -294,13 +294,27 @@ NonBlockingClient::connect(HostString host, uint16_t port) {
     return {};
 }
 
+void NonBlockingClient::disconnect() {
+    m_lastKnownConStatus = ENOTCONN;
+    close_socket();
+}
+
+///
+/// @brief Get last known connection status
+/// @return - expected(EINPROGRESS) if connection is still being attempted
+///         - expected(EISCONN) if already connected
+///         - expected(error code) if an error occurred during connection (e.g.,
+///           ECONNREFUSED)
+///         - unexpected(errno) if an error occurred while checking connection
+///           status
+///
 [[nodiscard]] std::expected<int, int>
 NonBlockingClient::get_last_connection_status() {
     if (!m_startedNewConAttempt) return m_lastKnownConStatus;
 
     /// Check if connect operation has been completed
 
-    auto pendingOpRes = new_error_codes_available();
+    auto pendingOpRes = socket_has_new_output_event();
     if (!pendingOpRes) return std::unexpected{pendingOpRes.error()};
     if (!pendingOpRes.value()) return EINPROGRESS;
 
@@ -325,33 +339,6 @@ NonBlockingClient::get_last_connection_status() {
     return m_lastKnownConStatus;
 }
 
-void NonBlockingClient::disconnect() {
-    m_lastKnownConStatus = ENOTCONN;
-    close_socket();
-}
-
-[[nodiscard]] std::expected<int, int>
-NonBlockingClient::send(std::span<const std::byte> data) {
-    // TODO: Do we need this?
-    auto conRes = get_last_connection_status();
-    if (!conRes) return std::unexpected{conRes.error()};
-    if (conRes.value() != EISCONN) {
-        spdlog::error("tcp::NonBlockingClient: Socket not connected");
-        return std::unexpected{ENOTCONN};
-    }
-
-    const int bytesWritten =
-        ::send(m_socket, (const char*)data.data(), data.size(), 0);
-
-    if (bytesWritten <= 0) {
-        spdlog::error("tcp::NonBlockingClient: send() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-
-    return bytesWritten;
-}
-
 bool NonBlockingClient::data_available() {
     auto conRes = get_last_connection_status();
     if (!conRes) return false;
@@ -367,6 +354,20 @@ bool NonBlockingClient::data_available() {
     return (m_pfdIn.revents & POLLIN);
 }
 
+[[nodiscard]] std::expected<int, int>
+NonBlockingClient::send(std::span<const std::byte> data) {
+    const int bytesWritten =
+        ::send(m_socket, (const char*)data.data(), data.size(), 0);
+
+    if (bytesWritten <= 0) {
+        spdlog::error("tcp::NonBlockingClient: send() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    return bytesWritten;
+}
+
 [[nodiscard]] std::expected<int, int>
 NonBlockingClient::recv(std::span<std::byte> buffer) {
     const int bytesReceived =
@@ -380,27 +381,12 @@ NonBlockingClient::recv(std::span<std::byte> buffer) {
     return {bytesReceived};
 }
 
-void NonBlockingClient::close_socket() {
-    if (shutdown(m_socket, 0) < 0) {
-        spdlog::debug("tcp::NonBlockingClient: shutdown() failed with errno={}",
-                      errno);
-    }
-
-    if (close(m_socket) < 0) {
-        spdlog::debug("tcp::NonBlockingClient: close() failed with errno={}",
-                      errno);
-    }
-
-    m_socket    = -1;
-    m_pfdOut.fd = -1;
-    m_pfdIn.fd  = -1;
-}
-
 [[nodiscard]] std::expected<void, int> NonBlockingClient::create_socket() {
     m_socket = socket(AF_INET, SOCK_STREAM, 0);
     if (m_socket < 1) {
         spdlog::error("tcp::NonBlockingClient: socket() failed with errno={}",
                       errno);
+        close_socket();
         return std::unexpected{errno};
     }
 
@@ -425,8 +411,29 @@ void NonBlockingClient::close_socket() {
     return {};
 }
 
+void NonBlockingClient::close_socket() {
+    if (shutdown(m_socket, 0) < 0) {
+        spdlog::debug("tcp::NonBlockingClient: shutdown() failed with errno={}",
+                      errno);
+    }
+
+    if (close(m_socket) < 0) {
+        spdlog::debug("tcp::NonBlockingClient: close() failed with errno={}",
+                      errno);
+    }
+
+    m_socket    = -1;
+    m_pfdOut.fd = -1;
+    m_pfdIn.fd  = -1;
+}
+
+
+///
+/// @return true if there is new output event, i.e., the connect() operation has
+/// completed (successfully or not)
+///
 [[nodiscard]] std::expected<bool, int>
-NonBlockingClient::new_error_codes_available() {
+NonBlockingClient::socket_has_new_output_event() {
     int ret = poll(&m_pfdOut, 1, 0);
     if (ret < 0) {
         spdlog::error("tcp::NonBlockingClient: poll() failed with errno={}",

src/tcp.hpp

@@ -1,24 +1,16 @@
 #pragma once
 
 
+// STL includes
 #include <array>
 #include <cerrno>
 #include <cstdint>
 #include <expected>
-#include <poll.h>
 #include <span>
-#include <spdlog/spdlog.h>
-#include <sys/socket.h>
 
 // C stdlib includes
-#include <arpa/inet.h>
-#include <expected>
-#include <fcntl.h>
-#include <netdb.h>
 #include <netinet/in.h>
-#include <netinet/tcp.h>
-#include <sys/socket.h>
-#include <sys/types.h>
+#include <sys/poll.h>
 
 
 namespace tcp {
@@ -26,52 +18,48 @@ namespace tcp {
 
 using HostString = std::array<char, 64>;
 
+
 //
 //
 // Non blocking server
 //
 //
 
-struct ServerSettings {
-    uint16_t port = 0;
-};
 
 class NonBlockingServer {
 public:
-    NonBlockingServer(ServerSettings settings);
+    NonBlockingServer()                                    = default;
+    NonBlockingServer(const NonBlockingServer&)            = delete;
+    NonBlockingServer(NonBlockingServer&&)                 = delete;
+    NonBlockingServer& operator=(const NonBlockingServer&) = delete;
+    NonBlockingServer& operator=(NonBlockingServer&&)      = delete;
     ~NonBlockingServer();
 
-    [[nodiscard]] std::expected<void, int> start_listening();
+    [[nodiscard]] std::expected<void, int> start_listening(uint16_t port);
+    void                                   stop_listening();
 
     bool                                   next_client_available();
     [[nodiscard]] std::expected<void, int> accept_next_client();
-    void                                   disconnect();
+    void                                   disconnect_from_client();
 
-    [[nodiscard]] std::expected<int, int>
-    send(std::span<const std::byte> data) const;
-
-    [[nodiscard]] std::expected<int, int>
-    recv(std::span<std::byte> buffer) const;
+    [[nodiscard]] std::expected<std::array<char, 16>, int>
+    get_client_ip_as_string();
 
     bool data_available();
 
-    [[nodiscard]] std::expected<std::array<char, 16>, int>
-    get_client_ip_as_string() const;
+    [[nodiscard]] std::expected<int, int> send(std::span<const std::byte> data);
+    [[nodiscard]] std::expected<int, int> recv(std::span<std::byte> buffer);
 
 private:
-    ServerSettings           m_settings;
-    const struct sockaddr_in m_serverAddress;
-    int                      m_serverSocket = -1;
+    int m_serverSocket = -1;
 
     pollfd m_serverPfdIn = {.fd = -1, .events = POLLIN};
     pollfd m_clientPfdIn = {.fd = -1, .events = POLLIN};
 
-    int             m_clientSocket = -1;
-    struct sockaddr m_clientAddress;
-    socklen_t       m_clientAddrLen = sizeof(m_clientAddress);
+    int             m_clientSocket  = -1;
+    struct sockaddr m_clientAddress = {0};
 
-
-    [[nodiscard]] std::expected<void, int> create_socket();
+    [[nodiscard]] std::expected<void, int> create_server_socket();
     void                                   close_server_socket();
     void                                   close_client_socket();
 };
@@ -86,12 +74,15 @@ private:
 
 class NonBlockingClient {
 public:
+    NonBlockingClient()                                    = default;
+    NonBlockingClient(const NonBlockingClient&)            = delete;
+    NonBlockingClient(NonBlockingClient&&)                 = delete;
+    NonBlockingClient& operator=(const NonBlockingClient&) = delete;
+    NonBlockingClient& operator=(NonBlockingClient&&)      = delete;
     ~NonBlockingClient();
 
-    // clang-format off
-    [[nodiscard]] std::expected<void, int>
-    connect(HostString host, uint16_t port);
-    // clang-format on
+    [[nodiscard]] std::expected<void, int> connect(const HostString& host,
+                                                   uint16_t          port);
 
     void disconnect();
 
@@ -99,8 +90,8 @@ public:
 
     bool data_available();
 
-    [[nodiscard]] std::expected<int, int> recv(std::span<std::byte> buffer);
     [[nodiscard]] std::expected<int, int> send(std::span<const std::byte> data);
+    [[nodiscard]] std::expected<int, int> recv(std::span<std::byte> buffer);
 
 private:
     int    m_socket = -1;
@@ -110,10 +101,10 @@ private:
     bool m_startedNewConAttempt = false;
     int  m_lastKnownConStatus   = ENOTCONN;
 
-    void close_socket();
-
     [[nodiscard]] std::expected<void, int> create_socket();
-    [[nodiscard]] std::expected<bool, int> new_error_codes_available();
+    void                                   close_socket();
+
+    [[nodiscard]] std::expected<bool, int> socket_has_new_output_event();
 };
 
 

tests/tcp.cpp

@@ -1,13 +1,17 @@
-#include "tcp.hpp"
-
 #include <gtest/gtest.h>
 
+// STL includes
+#include <cstring>
+
+// Project includes
+#include "tcp.hpp"
+
 
 TEST(TcpServer, Accept) {
-    tcp::NonBlockingServer server{{.port = 1234}};
+    tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
-    auto lisRes = server.start_listening();
+    auto lisRes = server.start_listening(1234);
 
     EXPECT_FALSE(server.next_client_available());
 
@@ -20,8 +24,86 @@ TEST(TcpServer, Accept) {
     EXPECT_FALSE(server.next_client_available());
 }
 
+TEST(TcpServer, RestartListening) {
+    tcp::NonBlockingServer server;
+    tcp::NonBlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    auto conRes = client.connect({"localhost"}, 1234);
+
+    EXPECT_TRUE(server.next_client_available());
+
+    auto lisRes2 = server.start_listening(2345);
+
+    EXPECT_FALSE(server.next_client_available());
+
+    auto conRes2 = client.connect({"localhost"}, 2345);
+
+    EXPECT_TRUE(server.next_client_available());
+
+    auto statRes2 = client.get_last_connection_status();
+    if (!statRes2) return;
+    EXPECT_EQ(statRes2.value(), EISCONN);
+}
+
+TEST(TcpServer, StopListening) {
+    tcp::NonBlockingServer server;
+    tcp::NonBlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    auto conRes = client.connect({"localhost"}, 1234);
+
+    EXPECT_TRUE(server.next_client_available());
+
+    server.stop_listening();
+
+    EXPECT_FALSE(server.next_client_available());
+
+    auto conRes2 = client.connect({"localhost"}, 1234);
+
+    EXPECT_EQ(client.get_last_connection_status().value(), ECONNREFUSED);
+}
+
+TEST(TcpServer, DataAvailable) {
+    tcp::NonBlockingServer server;
+    tcp::NonBlockingClient client;
+
+    EXPECT_FALSE(server.data_available());
+
+    auto lisRes = server.start_listening(1234);
+    auto conRes = client.connect({"localhost"}, 1234);
+    auto accRes = server.accept_next_client();
+
+    EXPECT_FALSE(server.data_available());
+
+    std::array<char, 14> txMsg   = {"Hello, World!"};
+    auto                 sendRes = client.send(std::as_bytes(std::span(txMsg)));
+    EXPECT_EQ(sendRes.value(), txMsg.size());
+    EXPECT_TRUE(server.data_available());
+
+    std::array<char, 1024> rxBuffer;
+    auto recvRes = server.recv(std::as_writable_bytes(std::span(rxBuffer)));
+    EXPECT_EQ(recvRes.value(), txMsg.size());
+    EXPECT_FALSE(server.data_available());
+}
+
+TEST(TcpServer, GetClientIPAsString) {
+    tcp::NonBlockingServer server;
+    tcp::NonBlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+    auto conRes = client.connect({"localhost"}, 1234);
+    auto accRes = server.accept_next_client();
+    auto ipRes  = server.get_client_ip_as_string();
+    if (!ipRes) return;
+
+    EXPECT_STREQ(ipRes.value().data(), "127.0.0.1");
+}
+
 TEST(TcpClient, Connect) {
-    tcp::NonBlockingServer server{{.port = 1234}};
+    tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
     /// Default connection status, i.e., before attempting connection
@@ -40,7 +122,7 @@ TEST(TcpClient, Connect) {
 
     /// Connection status when connection is acknowledged
 
-    auto lisRes = server.start_listening();
+    auto lisRes = server.start_listening(1234);
 
     auto conRes2 = client.connect({"localhost"}, 1234);
 
@@ -58,12 +140,12 @@ TEST(TcpClient, Connect) {
 }
 
 TEST(TcpClient, Reconnect) {
-    tcp::NonBlockingServer server1{{.port = 1234}};
-    tcp::NonBlockingServer server2{{.port = 2345}};
+    tcp::NonBlockingServer server1;
+    tcp::NonBlockingServer server2;
     tcp::NonBlockingClient client;
 
-    auto lisRes1 = server1.start_listening();
-    auto lisRes2 = server2.start_listening();
+    auto lisRes1 = server1.start_listening(1234);
+    auto lisRes2 = server2.start_listening(2345);
 
     auto conRes1 = client.connect({"localhost"}, 1234);
 
@@ -79,12 +161,12 @@ TEST(TcpClient, Reconnect) {
 }
 
 TEST(TcpClient, DataAvailable) {
-    tcp::NonBlockingServer server{{.port = 1234}};
+    tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
     EXPECT_FALSE(client.data_available());
 
-    auto lisRes = server.start_listening();
+    auto lisRes = server.start_listening(1234);
     auto conRes = client.connect({"localhost"}, 1234);
     auto accRes = server.accept_next_client();
 
@@ -104,34 +186,11 @@ TEST(TcpClient, DataAvailable) {
     EXPECT_FALSE(client.data_available());
 }
 
-TEST(TcpServer, DataAvailable) {
-    tcp::NonBlockingServer server{{.port = 1234}};
-    tcp::NonBlockingClient client;
-
-    EXPECT_FALSE(server.data_available());
-
-    auto lisRes = server.start_listening();
-    auto conRes = client.connect({"localhost"}, 1234);
-    auto accRes = server.accept_next_client();
-
-    EXPECT_FALSE(server.data_available());
-
-    std::array<char, 14> txMsg   = {"Hello, World!"};
-    auto                 sendRes = client.send(std::as_bytes(std::span(txMsg)));
-    EXPECT_EQ(sendRes.value(), txMsg.size());
-    EXPECT_TRUE(server.data_available());
-
-    std::array<char, 1024> rxBuffer;
-    auto recvRes = server.recv(std::as_writable_bytes(std::span(rxBuffer)));
-    EXPECT_EQ(recvRes.value(), txMsg.size());
-    EXPECT_FALSE(server.data_available());
-}
-
 TEST(TcpClientServer, ClientSendServerReceive) {
-    tcp::NonBlockingServer server{{.port = 1234}};
+    tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
-    auto lisRes = server.start_listening();
+    auto lisRes = server.start_listening(1234);
     auto conRes = client.connect({"localhost"}, 1234);
     auto accRes = server.accept_next_client();
 
@@ -148,10 +207,10 @@ TEST(TcpClientServer, ClientSendServerReceive) {
 }
 
 TEST(TcpClientServer, ClientReceiveServerSend) {
-    tcp::NonBlockingServer server{{.port = 1234}};
+    tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
-    auto lisRes = server.start_listening();
+    auto lisRes = server.start_listening(1234);
     auto conRes = client.connect({"localhost"}, 1234);
     auto accRes = server.accept_next_client();