Move functions to detail namespace

CMakeLists.txt

@@ -43,7 +43,7 @@ FetchContent_MakeAvailable(googletest)
 #
 
 
-add_executable(playground src/main.cpp src/tcp.cpp)
+add_executable(playground src/main.cpp src/tcp_server.cpp src/tcp_client.cpp)
 target_link_libraries(playground PRIVATE spdlog::spdlog)
 
 
@@ -54,24 +54,28 @@ target_link_libraries(playground PRIVATE spdlog::spdlog)
 #
 
 
+include(GoogleTest)
+
+
 enable_testing()
 
-add_executable(
-    tcp_test
-    tests/tcp.cpp
-    src/tcp.cpp
-)
-target_link_libraries(
-  tcp_test
-  spdlog::spdlog
-  GTest::gtest_main
-)
-target_include_directories(
-  tcp_test
-  PRIVATE
-  src
+add_executable(tcp_blocking_test
+    tests/tcp_blocking.cpp
+    src/tcp_server.cpp
+    src/tcp_client.cpp
 )
+target_link_libraries(tcp_blocking_test spdlog::spdlog GTest::gtest_main)
+target_include_directories(tcp_blocking_test PRIVATE src)
 
-include(GoogleTest)
-gtest_discover_tests(tcp_test)
+gtest_discover_tests(tcp_blocking_test)
+
+add_executable(tcp_non_blocking_test
+    tests/tcp_non_blocking.cpp
+    src/tcp_server.cpp
+    src/tcp_client.cpp
+)
+target_link_libraries(tcp_non_blocking_test spdlog::spdlog GTest::gtest_main)
+target_include_directories(tcp_non_blocking_test PRIVATE src)
+
+gtest_discover_tests(tcp_non_blocking_test)
 

src/common.hpp

@@ -0,0 +1,54 @@
+#pragma once
+
+
+// STL includes
+#include <expected>
+
+// C stdlib includes
+#include <netdb.h>
+#include <netinet/in.h>
+
+// Library includes
+#include <spdlog/spdlog.h>
+
+
+namespace tcp {
+
+
+namespace detail {
+
+
+inline std::expected<sockaddr_in, int> resolve_remote_address(const char* host,
+                                                              uint16_t port) {
+    hostent* server = gethostbyname(host);
+    if (server == nullptr) {
+        spdlog::error("tcp: get_host_by_name() failed with h_errno={}",
+                      h_errno);
+        return std::unexpected{h_errno};
+    }
+
+    sockaddr_in address{};
+    address.sin_family = AF_INET;
+    address.sin_port   = htons(port);
+    bcopy((char*)server->h_addr, (char*)&address.sin_addr.s_addr,
+          server->h_length);
+
+    return address;
+}
+
+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;
+    address.sin_port        = htons(port);
+    return address;
+}
+
+
+} // namespace detail
+
+
+using HostString = std::array<char, 64>;
+
+
+} // namespace tcp

src/main.cpp

@@ -2,7 +2,7 @@
 #include <spdlog/spdlog.h>
 
 // Project includes
-#include "tcp.hpp"
+#include "tcp_server.hpp"
 
 
 int main() {

src/tcp_client.cpp

@@ -0,0 +1,300 @@
+#include "tcp_client.hpp"
+
+// C stdlib includes
+#include <arpa/inet.h>
+#include <fcntl.h>
+#include <netdb.h>
+
+// Library includes
+#include <spdlog/spdlog.h>
+
+
+namespace tcp {
+
+
+//
+//
+// Blocking client
+//
+//
+
+
+BlockingClient::~BlockingClient() {
+    close_socket();
+}
+
+[[nodiscard]] std::expected<void, int>
+BlockingClient::connect(const HostString& host, uint16_t port) {
+    /// Resolve host
+
+    auto addrRes = detail::resolve_remote_address(host.data(), port);
+    if (!addrRes) return std::unexpected{addrRes.error()};
+    sockaddr_in serverAddress = addrRes.value();
+
+    /// Create socket
+
+    close_socket();
+
+    m_socket = socket(AF_INET, SOCK_STREAM, 0);
+    if (m_socket < 1) {
+        spdlog::error("tcp::BlockingClient: socket() failed with errno={}",
+                      errno);
+        close_socket();
+        return std::unexpected{errno};
+    }
+
+    /// Connect
+
+    int connectRes = ::connect(m_socket, (struct sockaddr*)&serverAddress,
+                               sizeof(serverAddress));
+
+    if (connectRes < 0) {
+        spdlog::error("tcp::BlockingClient: connect() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    return {};
+}
+
+void BlockingClient::disconnect() {
+    close_socket();
+}
+
+[[nodiscard]] std::expected<int, int>
+BlockingClient::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::BlockingClient: send() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    return bytesWritten;
+}
+
+[[nodiscard]] std::expected<int, int>
+BlockingClient::recv(std::span<std::byte> buffer) {
+    const int bytesReceived =
+        ::recv(m_socket, (char*)buffer.data(), buffer.size(), 0);
+
+    if (bytesReceived < 0) {
+        spdlog::error("tcp::BlockingClient: recv() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+    return {bytesReceived};
+}
+
+void BlockingClient::close_socket() {
+    if (shutdown(m_socket, 0) < 0) {
+        spdlog::debug("tcp::BlockingClient: shutdown() failed with errno={}",
+                      errno);
+    }
+
+    if (close(m_socket) < 0) {
+        spdlog::debug("tcp::BlockingClient: close() failed with errno={}",
+                      errno);
+    }
+
+    m_socket = -1;
+}
+
+
+//
+//
+// Non blocking client
+//
+//
+
+
+NonBlockingClient::~NonBlockingClient() {
+    close_socket();
+}
+
+[[nodiscard]] std::expected<void, int>
+NonBlockingClient::connect(const HostString& host, uint16_t port) {
+    /// Resolve host
+
+    auto addrRes = detail::resolve_remote_address(host.data(), port);
+    if (!addrRes) return std::unexpected{addrRes.error()};
+    sockaddr_in serverAddress = addrRes.value();
+
+    /// Create socket
+
+    close_socket();
+    if (auto res = create_socket(); !res) {
+        return std::unexpected{res.error()};
+    }
+
+    /// Connect
+
+    int connectRes = ::connect(m_socket, (struct sockaddr*)&serverAddress,
+                               sizeof(serverAddress));
+
+    if (connectRes < 0 && errno != EINPROGRESS) {
+        spdlog::error("tcp::NonBlockingClient: connect() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    m_startedNewConAttempt = true;
+
+    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 = socket_has_new_output_event();
+    if (!pendingOpRes) return std::unexpected{pendingOpRes.error()};
+    if (!pendingOpRes.value()) return EINPROGRESS;
+
+    m_startedNewConAttempt = false;
+
+    /// Check for connection errors
+
+    int       err = 0;
+    socklen_t len = sizeof(err);
+    if (getsockopt(m_socket, SOL_SOCKET, SO_ERROR, &err, &len) < 0) {
+        spdlog::error(
+            "tcp::NonBlockingClient: getsockopt() failed with errno={}", errno);
+        return std::unexpected{errno};
+    }
+
+    if (err == 0) {
+        m_lastKnownConStatus = EISCONN;
+    } else {
+        m_lastKnownConStatus = err;
+    }
+
+    return m_lastKnownConStatus;
+}
+
+bool NonBlockingClient::data_available() {
+    auto conRes = get_last_connection_status();
+    if (!conRes) return false;
+    if (conRes.value() != EISCONN) return false;
+
+    int ret = poll(&m_pfdIn, 1, 0);
+    if (ret < 0) {
+        spdlog::error("tcp::NonBlockingClient: poll() failed with errno={}",
+                      errno);
+        return false;
+    }
+
+    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 =
+        ::recv(m_socket, (char*)buffer.data(), buffer.size(), 0);
+
+    if (bytesReceived < 0) {
+        spdlog::error("tcp::NonBlockingClient: recv() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+    return {bytesReceived};
+}
+
+[[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};
+    }
+
+    m_pfdOut.fd = m_socket;
+    m_pfdIn.fd  = m_socket;
+
+    auto currentFlags = fcntl(m_socket, F_GETFL, 0);
+    if (currentFlags == -1) {
+        spdlog::error("tcp::NonBlockingClient: fcntl() failed with errno={}",
+                      errno);
+        close_socket();
+        return std::unexpected{errno};
+    }
+
+    if (fcntl(m_socket, F_SETFL, (currentFlags) | O_NONBLOCK) == -1) {
+        spdlog::error("tcp::NonBlockingClient: fcntl() failed with errno={}",
+                      errno);
+        close_socket();
+        return std::unexpected{errno};
+    }
+
+    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::socket_has_new_output_event() {
+    int ret = poll(&m_pfdOut, 1, 0);
+    if (ret < 0) {
+        spdlog::error("tcp::NonBlockingClient: poll() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    // ret == 0 means the operation timed out, i.e., no new events
+    return (ret != 0);
+}
+
+
+} // namespace tcp

src/tcp_client.hpp

@@ -0,0 +1,95 @@
+#pragma once
+
+
+// STL includes
+#include <cerrno>
+#include <cstdint>
+#include <expected>
+#include <span>
+
+// C stdlib includes
+#include <netinet/in.h>
+#include <sys/poll.h>
+
+// Project includes
+#include "common.hpp"
+
+
+namespace tcp {
+
+
+//
+//
+// Blocking client
+//
+//
+
+
+class BlockingClient {
+public:
+    BlockingClient()                                 = default;
+    BlockingClient(const BlockingClient&)            = delete;
+    BlockingClient(BlockingClient&&)                 = delete;
+    BlockingClient& operator=(const BlockingClient&) = delete;
+    BlockingClient& operator=(BlockingClient&&)      = delete;
+    ~BlockingClient();
+
+    [[nodiscard]] std::expected<void, int> connect(const HostString& host,
+                                                   uint16_t          port);
+
+    void disconnect();
+
+    [[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;
+
+    void close_socket();
+};
+
+
+//
+//
+// Non blocking client
+//
+//
+
+
+class NonBlockingClient {
+public:
+    NonBlockingClient()                                    = default;
+    NonBlockingClient(const NonBlockingClient&)            = delete;
+    NonBlockingClient(NonBlockingClient&&)                 = delete;
+    NonBlockingClient& operator=(const NonBlockingClient&) = delete;
+    NonBlockingClient& operator=(NonBlockingClient&&)      = delete;
+    ~NonBlockingClient();
+
+    [[nodiscard]] std::expected<void, int> connect(const HostString& host,
+                                                   uint16_t          port);
+
+    void disconnect();
+
+    [[nodiscard]] std::expected<int, int> get_last_connection_status();
+
+    bool data_available();
+
+    [[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;
+    pollfd m_pfdOut = {.fd = -1, .events = POLLOUT};
+    pollfd m_pfdIn  = {.fd = -1, .events = POLLIN};
+
+    bool m_startedNewConAttempt = false;
+    int  m_lastKnownConStatus   = ENOTCONN;
+
+    [[nodiscard]] std::expected<void, int> create_socket();
+    void                                   close_socket();
+
+    [[nodiscard]] std::expected<bool, int> socket_has_new_output_event();
+};
+
+
+} // namespace tcp

src/tcp_server.cpp

@@ -1,4 +1,4 @@
-#include "tcp.hpp"
+#include "tcp_server.hpp"
 
 // C stdlib includes
 #include <arpa/inet.h>
@@ -8,43 +8,177 @@
 // Library includes
 #include <spdlog/spdlog.h>
 
-
-namespace {
-
-
-std::expected<sockaddr_in, int> resolve_remote_address(const char* host,
-                                                       uint16_t    port) {
-    hostent* server = gethostbyname(host);
-    if (server == nullptr) {
-        spdlog::error("tcp: get_host_by_name() failed with h_errno={}",
-                      h_errno);
-        return std::unexpected{h_errno};
-    }
-
-    sockaddr_in address{};
-    address.sin_family = AF_INET;
-    address.sin_port   = htons(port);
-    bcopy((char*)server->h_addr, (char*)&address.sin_addr.s_addr,
-          server->h_length);
-
-    return address;
-}
-
-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;
-    address.sin_port        = htons(port);
-    return address;
-}
-
-
-} // namespace
+// Project includes
+#include "common.hpp"
 
 
 namespace tcp {
 
 
+//
+//
+// Blocking server
+//
+//
+
+
+BlockingServer::~BlockingServer() {
+    close_client_socket();
+    close_server_socket();
+}
+
+///
+/// @details Calling this repeatedly closes the previous socket and creates a
+/// new one.
+///
+std::expected<void, int> BlockingServer::start_listening(uint16_t port) {
+    /// Create socket
+
+    close_server_socket();
+    if (auto res = create_server_socket(); !res) {
+        return std::unexpected{res.error()};
+    }
+
+    /// Bind socket and start listening
+
+    const struct sockaddr_in serverAddress = detail::get_local_address(port);
+
+    if (::bind(m_serverSocket, (struct sockaddr*)&serverAddress,
+               sizeof(serverAddress)) != 0) {
+        spdlog::error("tcp::BlockingServer: bind() failed with errno={}",
+                      errno);
+        close_server_socket();
+        return std::unexpected{errno};
+    };
+
+    if (::listen(m_serverSocket, 1) != 0) {
+        spdlog::error("tcp::BlockingServer: listen() failed with errno={}",
+                      errno);
+        close_server_socket();
+        return std::unexpected{errno};
+    }
+
+    return {};
+}
+
+void BlockingServer::stop_listening() {
+    close_server_socket();
+}
+
+[[nodiscard]] std::expected<void, int> BlockingServer::accept() {
+    disconnect_from_client();
+
+    socklen_t clientAddrLen = sizeof(m_clientAddress);
+
+    int result = ::accept(m_serverSocket, (struct sockaddr*)&m_clientAddress,
+                          &clientAddrLen);
+    if (result < 0) return std::unexpected{errno};
+
+    m_clientSocket = result;
+
+    return {};
+}
+
+void BlockingServer::disconnect_from_client() {
+    close_client_socket();
+}
+
+[[nodiscard]] std::expected<std::array<char, 16>, int>
+BlockingServer::get_client_ip_as_string() {
+    std::array<char, 16> addrStr;
+
+    if (inet_ntop(AF_INET, &((struct sockaddr_in*)&m_clientAddress)->sin_addr,
+                  addrStr.data(), addrStr.size()) == nullptr) {
+        spdlog::error("tcp::BlockingServer: inet_ntop() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    // if (inet_ntoa_r(((struct sockaddr_in*)&m_clientAddress)->sin_addr,
+    //               addrStr.data(), addrStr.size()) == nullptr) {
+    //     return std::unexpected{errno};
+    // }
+
+    return addrStr;
+}
+
+[[nodiscard]] std::expected<int, int>
+BlockingServer::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::BlockingServer: send() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+
+    return bytesWritten;
+}
+
+[[nodiscard]] std::expected<int, int>
+BlockingServer::recv(std::span<std::byte> buffer) {
+    const int bytesReceived =
+        ::recv(m_clientSocket, (char*)buffer.data(), buffer.size(), 0);
+
+    if (bytesReceived < 0) {
+        spdlog::error("tcp::BlockingServer: recv() failed with errno={}",
+                      errno);
+        return std::unexpected{errno};
+    }
+    return {bytesReceived};
+}
+
+[[nodiscard]] std::expected<void, int> BlockingServer::create_server_socket() {
+    m_serverSocket = socket(AF_INET, SOCK_STREAM, 0);
+    if (m_serverSocket < 1) {
+        spdlog::error("tcp::BlockingServer: socket() failed with errno={}",
+                      errno);
+        close_server_socket();
+        return std::unexpected{errno};
+    }
+
+    int flag = 1;
+    if (::setsockopt(m_serverSocket, SOL_SOCKET, SO_REUSEADDR, &flag,
+                     sizeof(flag)) < 0) {
+        spdlog::error("tcp::BlockingServer: setsockopt() failed with errno={}",
+                      errno);
+        close_server_socket();
+        return std::unexpected{errno};
+    }
+
+    return {};
+}
+
+void BlockingServer::close_server_socket() {
+    if (shutdown(m_serverSocket, 0) < 0) {
+        spdlog::debug("tcp::BlockingServer: shutdown() failed with errno={}",
+                      errno);
+    }
+
+    if (close(m_serverSocket) < 0) {
+        spdlog::debug("tcp::BlockingServer: close() failed with errno={}",
+                      errno);
+    }
+
+    m_serverSocket = -1;
+}
+
+void BlockingServer::close_client_socket() {
+    if (shutdown(m_clientSocket, 0) < 0) {
+        spdlog::debug("tcp::BlockingServer: shutdown() failed with errno={}",
+                      errno);
+    }
+
+    if (close(m_clientSocket) < 0) {
+        spdlog::debug("tcp::BlockingServer: close() failed with errno={}",
+                      errno);
+    }
+
+    m_clientSocket = -1;
+}
+
+
 //
 //
 // Non blocking server
@@ -69,9 +203,9 @@ std::expected<void, int> NonBlockingServer::start_listening(uint16_t port) {
         return std::unexpected{res.error()};
     }
 
-    /// Bin socket and start listening
+    /// Bind socket and start listening
 
-    const struct sockaddr_in serverAddress = get_local_address(port);
+    const struct sockaddr_in serverAddress = detail::get_local_address(port);
 
     if (::bind(m_serverSocket, (struct sockaddr*)&serverAddress,
                sizeof(serverAddress)) != 0) {
@@ -252,198 +386,4 @@ void NonBlockingServer::close_client_socket() {
 }
 
 
-//
-//
-// Non blocking client
-//
-//
-
-
-NonBlockingClient::~NonBlockingClient() {
-    close_socket();
-}
-
-[[nodiscard]] std::expected<void, int>
-NonBlockingClient::connect(const HostString& host, uint16_t port) {
-    /// Resolve host
-
-    auto addrRes = resolve_remote_address(host.data(), port);
-    if (!addrRes) return std::unexpected{addrRes.error()};
-    sockaddr_in serverAddress = addrRes.value();
-
-    /// Create socket
-
-    close_socket();
-    if (auto res = create_socket(); !res) {
-        return std::unexpected{res.error()};
-    }
-
-    /// Connect
-
-    int connectRes = ::connect(m_socket, (struct sockaddr*)&serverAddress,
-                               sizeof(serverAddress));
-
-    if (connectRes < 0 && errno != EINPROGRESS) {
-        spdlog::error("tcp::NonBlockingClient: connect() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-
-    m_startedNewConAttempt = true;
-
-    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 = socket_has_new_output_event();
-    if (!pendingOpRes) return std::unexpected{pendingOpRes.error()};
-    if (!pendingOpRes.value()) return EINPROGRESS;
-
-    m_startedNewConAttempt = false;
-
-    /// Check for connection errors
-
-    int       err = 0;
-    socklen_t len = sizeof(err);
-    if (getsockopt(m_socket, SOL_SOCKET, SO_ERROR, &err, &len) < 0) {
-        spdlog::error(
-            "tcp::NonBlockingClient: getsockopt() failed with errno={}", errno);
-        return std::unexpected{errno};
-    }
-
-    if (err == 0) {
-        m_lastKnownConStatus = EISCONN;
-    } else {
-        m_lastKnownConStatus = err;
-    }
-
-    return m_lastKnownConStatus;
-}
-
-bool NonBlockingClient::data_available() {
-    auto conRes = get_last_connection_status();
-    if (!conRes) return false;
-    if (conRes.value() != EISCONN) return false;
-
-    int ret = poll(&m_pfdIn, 1, 0);
-    if (ret < 0) {
-        spdlog::error("tcp::NonBlockingClient: poll() failed with errno={}",
-                      errno);
-        return false;
-    }
-
-    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 =
-        ::recv(m_socket, (char*)buffer.data(), buffer.size(), 0);
-
-    if (bytesReceived < 0) {
-        spdlog::error("tcp::NonBlockingClient: recv() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-    return {bytesReceived};
-}
-
-[[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};
-    }
-
-    m_pfdOut.fd = m_socket;
-    m_pfdIn.fd  = m_socket;
-
-    auto currentFlags = fcntl(m_socket, F_GETFL, 0);
-    if (currentFlags == -1) {
-        spdlog::error("tcp::NonBlockingClient: fcntl() failed with errno={}",
-                      errno);
-        close_socket();
-        return std::unexpected{errno};
-    }
-
-    if (fcntl(m_socket, F_SETFL, (currentFlags) | O_NONBLOCK) == -1) {
-        spdlog::error("tcp::NonBlockingClient: fcntl() failed with errno={}",
-                      errno);
-        close_socket();
-        return std::unexpected{errno};
-    }
-
-    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::socket_has_new_output_event() {
-    int ret = poll(&m_pfdOut, 1, 0);
-    if (ret < 0) {
-        spdlog::error("tcp::NonBlockingClient: poll() failed with errno={}",
-                      errno);
-        return std::unexpected{errno};
-    }
-
-    // ret == 0 means the operation timed out, i.e., no new events
-    return (ret != 0);
-}
-
-
 } // namespace tcp

src/tcp_server.hpp

@@ -2,7 +2,6 @@
 
 
 // STL includes
-#include <array>
 #include <cerrno>
 #include <cstdint>
 #include <expected>
@@ -16,7 +15,44 @@
 namespace tcp {
 
 
-using HostString = std::array<char, 64>;
+//
+//
+// Blocking server
+//
+//
+
+
+class BlockingServer {
+public:
+    BlockingServer()                                 = default;
+    BlockingServer(const BlockingServer&)            = delete;
+    BlockingServer(BlockingServer&&)                 = delete;
+    BlockingServer& operator=(const BlockingServer&) = delete;
+    BlockingServer& operator=(BlockingServer&&)      = delete;
+    ~BlockingServer();
+
+    [[nodiscard]] std::expected<void, int> start_listening(uint16_t port);
+    void                                   stop_listening();
+
+    [[nodiscard]] std::expected<void, int> accept();
+    void                                   disconnect_from_client();
+
+    [[nodiscard]] std::expected<std::array<char, 16>, int>
+    get_client_ip_as_string();
+
+    [[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_serverSocket = -1;
+
+    int             m_clientSocket  = -1;
+    struct sockaddr m_clientAddress = {0};
+
+    [[nodiscard]] std::expected<void, int> create_server_socket();
+    void                                   close_server_socket();
+    void                                   close_client_socket();
+};
 
 
 //
@@ -65,47 +101,4 @@ private:
 };
 
 
-//
-//
-// Non blocking client
-//
-//
-
-
-class NonBlockingClient {
-public:
-    NonBlockingClient()                                    = default;
-    NonBlockingClient(const NonBlockingClient&)            = delete;
-    NonBlockingClient(NonBlockingClient&&)                 = delete;
-    NonBlockingClient& operator=(const NonBlockingClient&) = delete;
-    NonBlockingClient& operator=(NonBlockingClient&&)      = delete;
-    ~NonBlockingClient();
-
-    [[nodiscard]] std::expected<void, int> connect(const HostString& host,
-                                                   uint16_t          port);
-
-    void disconnect();
-
-    [[nodiscard]] std::expected<int, int> get_last_connection_status();
-
-    bool data_available();
-
-    [[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;
-    pollfd m_pfdOut = {.fd = -1, .events = POLLOUT};
-    pollfd m_pfdIn  = {.fd = -1, .events = POLLIN};
-
-    bool m_startedNewConAttempt = false;
-    int  m_lastKnownConStatus   = ENOTCONN;
-
-    [[nodiscard]] std::expected<void, int> create_socket();
-    void                                   close_socket();
-
-    [[nodiscard]] std::expected<bool, int> socket_has_new_output_event();
-};
-
-
 } // namespace tcp

tests/tcp_blocking.cpp

@@ -0,0 +1,202 @@
+#include <gtest/gtest.h>
+
+// STL includes
+#include <cstring>
+#include <thread>
+
+// Project includes
+#include "tcp_client.hpp"
+#include "tcp_server.hpp"
+
+
+TEST(BlockingTcpServer, Accept) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    std::thread clientThread([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes.has_value());
+    });
+
+    std::thread serverThread([&server]() {
+        auto accRes = server.accept();
+        EXPECT_TRUE(accRes.has_value());
+    });
+
+    serverThread.join();
+    clientThread.join();
+}
+
+TEST(BlockingTcpServer, RestartListening) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    std::thread clientThread([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes.has_value());
+    });
+
+    clientThread.join();
+
+    auto lisRes2 = server.start_listening(2345);
+
+    std::thread clientThread2([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_FALSE(conRes.has_value());
+    });
+
+    clientThread2.join();
+
+    std::thread clientThread3([&client]() {
+        auto conRes2 = client.connect({"localhost"}, 2345);
+        EXPECT_TRUE(conRes2.has_value());
+    });
+
+    clientThread3.join();
+}
+
+TEST(BlockingTcpServer, StopListening) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    std::thread clientThread([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes.has_value());
+    });
+
+    clientThread.join();
+
+    server.stop_listening();
+
+    std::thread clientThread2([&client]() {
+        auto conRes2 = client.connect({"localhost"}, 1234);
+        EXPECT_FALSE(conRes2.has_value());
+    });
+
+    clientThread2.join();
+}
+
+TEST(BlockingTcpServer, MultipleAccept) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client1;
+    tcp::BlockingClient client2;
+
+    auto lisRes1 = server.start_listening(1234);
+
+    std::thread clientThread1([&client1]() {
+        auto conRes1 = client1.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes1.has_value());
+    });
+
+    std::thread clientThread2([&client2]() {
+        auto conRes2 = client2.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes2.has_value());
+    });
+
+    std::thread serverThread([&server]() {
+        auto accRes1 = server.accept();
+        EXPECT_TRUE(accRes1.has_value());
+
+        auto accRes2 = server.accept();
+        EXPECT_TRUE(accRes2.has_value());
+    });
+
+    clientThread1.join();
+    clientThread2.join();
+    serverThread.join();
+}
+
+TEST(BlockingTcpServer, GetClientIPAsString) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+    auto conRes = client.connect({"localhost"}, 1234);
+    auto accRes = server.accept();
+
+    auto ipRes = server.get_client_ip_as_string();
+    if (!ipRes) return;
+
+    EXPECT_STREQ(ipRes.value().data(), "127.0.0.1");
+}
+
+TEST(BlockingTcpClient, Connect) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+
+    std::thread clientThread([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes.has_value());
+    });
+
+    clientThread.join();
+}
+
+TEST(BlockingClient, Reconnect) {
+    tcp::BlockingServer server1;
+    tcp::BlockingServer server2;
+    tcp::BlockingClient client;
+
+    auto lisRes1 = server1.start_listening(1234);
+    auto lisRes2 = server2.start_listening(2345);
+
+    std::thread clientThread([&client]() {
+        auto conRes = client.connect({"localhost"}, 1234);
+        EXPECT_TRUE(conRes.has_value());
+    });
+
+    clientThread.join();
+
+    std::thread clientThread2([&client]() {
+        auto conRes2 = client.connect({"localhost"}, 2345);
+        EXPECT_TRUE(conRes2.has_value());
+    });
+
+    clientThread2.join();
+}
+
+TEST(BlockingTcpClientServer, ClientSendServerReceive) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+    auto conRes = client.connect({"localhost"}, 1234);
+    auto accRes = server.accept();
+
+    std::array<char, 14> txMsg   = {"Hello, World!"};
+    auto                 sendRes = client.send(std::as_bytes(std::span(txMsg)));
+
+    EXPECT_EQ(sendRes.value(), txMsg.size());
+
+    std::array<char, 1024> rxBuffer;
+    auto recvRes = server.recv(std::as_writable_bytes(std::span(rxBuffer)));
+    EXPECT_EQ(recvRes.value(), txMsg.size());
+    EXPECT_EQ(std::strcmp(txMsg.data(), rxBuffer.data()), 0);
+}
+
+TEST(BlockingTcpClientServer, ClientReceiveServerSend) {
+    tcp::BlockingServer server;
+    tcp::BlockingClient client;
+
+    auto lisRes = server.start_listening(1234);
+    auto conRes = client.connect({"localhost"}, 1234);
+    auto accRes = server.accept();
+
+    std::array<char, 14> txMsg   = {"Hello, World!"};
+    auto                 sendRes = server.send(std::as_bytes(std::span(txMsg)));
+
+    EXPECT_EQ(sendRes.value(), txMsg.size());
+
+    std::array<char, 1024> rxBuffer;
+    auto recvRes = client.recv(std::as_writable_bytes(std::span(rxBuffer)));
+    EXPECT_EQ(recvRes.value(), txMsg.size());
+    EXPECT_EQ(std::strcmp(txMsg.data(), rxBuffer.data()), 0);
+}

tests/tcp_non_blocking.cpp

@@ -4,10 +4,11 @@
 #include <cstring>
 
 // Project includes
-#include "tcp.hpp"
+#include "tcp_client.hpp"
+#include "tcp_server.hpp"
 
 
-TEST(TcpServer, Accept) {
+TEST(NonBlockingTcpServer, Accept) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -24,7 +25,7 @@ TEST(TcpServer, Accept) {
     EXPECT_FALSE(server.next_client_available());
 }
 
-TEST(TcpServer, RestartListening) {
+TEST(NonBlockingTcpServer, RestartListening) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -47,7 +48,7 @@ TEST(TcpServer, RestartListening) {
     EXPECT_EQ(statRes2.value(), EISCONN);
 }
 
-TEST(TcpServer, StopListening) {
+TEST(NonBlockingTcpServer, StopListening) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -66,7 +67,7 @@ TEST(TcpServer, StopListening) {
     EXPECT_EQ(client.get_last_connection_status().value(), ECONNREFUSED);
 }
 
-TEST(TcpServer, DataAvailable) {
+TEST(NonBlockingTcpServer, DataAvailable) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -89,7 +90,7 @@ TEST(TcpServer, DataAvailable) {
     EXPECT_FALSE(server.data_available());
 }
 
-TEST(TcpServer, GetClientIPAsString) {
+TEST(NonBlockingTcpServer, GetClientIPAsString) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -102,7 +103,7 @@ TEST(TcpServer, GetClientIPAsString) {
     EXPECT_STREQ(ipRes.value().data(), "127.0.0.1");
 }
 
-TEST(TcpClient, Connect) {
+TEST(NonBlockingTcpClient, Connect) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -139,7 +140,7 @@ TEST(TcpClient, Connect) {
     EXPECT_EQ(statRes4.value(), ECONNREFUSED);
 }
 
-TEST(TcpClient, Reconnect) {
+TEST(NonBlockingTcpClient, Reconnect) {
     tcp::NonBlockingServer server1;
     tcp::NonBlockingServer server2;
     tcp::NonBlockingClient client;
@@ -160,7 +161,7 @@ TEST(TcpClient, Reconnect) {
     EXPECT_EQ(statRes2.value(), EISCONN);
 }
 
-TEST(TcpClient, DataAvailable) {
+TEST(NonBlockingTcpClient, DataAvailable) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -186,7 +187,7 @@ TEST(TcpClient, DataAvailable) {
     EXPECT_FALSE(client.data_available());
 }
 
-TEST(TcpClientServer, ClientSendServerReceive) {
+TEST(NonBlockingTcpClientServer, ClientSendServerReceive) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;
 
@@ -206,7 +207,7 @@ TEST(TcpClientServer, ClientSendServerReceive) {
     EXPECT_EQ(std::strcmp(txMsg.data(), rxBuffer.data()), 0);
 }
 
-TEST(TcpClientServer, ClientReceiveServerSend) {
+TEST(NonBlockingTcpClientServer, ClientReceiveServerSend) {
     tcp::NonBlockingServer server;
     tcp::NonBlockingClient client;