【C++】Linux平台C++实现Unix域、TCP/IP、UDP socket通信
Unix 域套接字
Unix 域套接字非常适合在同一台机器上的不同进程之间进行高效的通信。由于它们不需要网络协议栈，因此在性能上通常优于 TCP/IP 套接字。
Socket server端
StartSocketServer.cpp源代码：
#include <iostream>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <cstring>
#include <string.h>constexpr const char *SOCKET_PATH = "./socket"; // Unix socket 文件路径void StartSocketServer() {// 创建一个 Unix 域套接字std::cout << "Starting Socket Server..." << std::endl;int serverSocketFd = socket(AF_UNIX, SOCK_STREAM, 0);if (serverSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}std::cout << "Socket created with file descriptor: " << serverSocketFd << std::endl;// 绑定套接字到指定路径sockaddr_un serverAddr;serverAddr.sun_family = AF_UNIX;strncpy(serverAddr.sun_path, SOCKET_PATH, sizeof(serverAddr.sun_path) - 1);unlink(serverAddr.sun_path); // 确保路径不存在if (bind(serverSocketFd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {std::cerr << "Error binding socket" << std::endl;close(serverSocketFd);return;}// 监听传入的连接if (listen(serverSocketFd, 5) == -1) {std::cerr << "Error listening for connections" << std::endl;close(serverSocketFd);return;}std::cout << "Server is listening for incoming connections..." << std::endl;while (true) {// 接受传入的连接std::cout << "Waiting for client connection..." << std::endl;int clientSocketFd = accept(serverSocketFd, nullptr, nullptr);if (clientSocketFd == -1) {std::cerr << "Error accepting connection" << std::endl;close(serverSocketFd);return;}std::cout << "Client connected, clientSocketFd: " << clientSocketFd << std::endl;// 接收来自客户端的数据char buffer[256];ssize_t bytesReceived = recv(clientSocketFd, buffer, sizeof(buffer) - 1, 0);if (bytesReceived > 0) {buffer[bytesReceived] = '\0'; // Null-terminate the received datastd::cout << "Received data: " << buffer << std::endl;// 发送响应给客户端const char *response = "OK";send(clientSocketFd, response, strlen(response), 0);std::cout << "Response sent to client." << std::endl;} else {std::cerr << "Error receiving data" << std::endl;}// 关闭客户端套接字close(clientSocketFd);std::cout << "Client socket closed." << std::endl;}// 关闭服务器套接字（虽然在此代码中不会到达）close(serverSocketFd);
}int main() {std::cout << "Hello, World!" << std::endl;StartSocketServer(); // 启动套接字服务器return 0;
}
使用g++编译生成可执行文件StartSocketServer：
g++ -o StartSocketServer StartSocketServer.cpp启动socket server端：
./StartSocketServer启动后socket server端打印如下：
Hello, World!
Starting Socket Server...
Socket created with file descriptor: 3
Server is listening for incoming connections...
Waiting for client connection...Socket client端
StartSocketClient.cpp源代码：
#include <iostream>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <cstring>constexpr const char *SOCKET_PATH = "./socket"; // Unix socket 文件路径void StartSocketClient() {// 创建一个 Unix 域套接字int clientSocketFd = socket(AF_UNIX, SOCK_STREAM, 0);if (clientSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}// 设置服务器地址结构sockaddr_un serverAddr;serverAddr.sun_family = AF_UNIX;strncpy(serverAddr.sun_path, SOCKET_PATH, sizeof(serverAddr.sun_path) - 1);// 连接到服务器if (connect(clientSocketFd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {std::cerr << "Error connecting to socket" << std::endl;close(clientSocketFd);return;}std::cout << "Connected to server!" << std::endl;// 向服务器发送消息const char *message = "Message sent by client!";ssize_t bytesSent = send(clientSocketFd, message, strlen(message), 0);if (bytesSent == -1) {std::cerr << "Error sending message" << std::endl;} else {std::cout << "Message sent: " << message << std::endl;}// 可选：接收来自服务器的响应char buffer[256];ssize_t bytesReceived = recv(clientSocketFd, buffer, sizeof(buffer) - 1, 0);if (bytesReceived > 0) {buffer[bytesReceived] = '\0'; // Null-terminate the received datastd::cout << "Received from server: " << buffer << std::endl;} else if (bytesReceived == -1) {std::cerr << "Error receiving data" << std::endl;}// 关闭套接字close(clientSocketFd);
}int main() {StartSocketClient(); // 启动套接字客户端return 0;
}
使用g++编译生成可执行文件StartSocketClient：
g++ -o StartSocketClient StartSocketClient.cpp启动socket client端：
./StartSocketClient 启动后socket client端打印如下：
Connected to server!
Message sent: Message sent by client!
Received from server: OKsocket server端打印如下：
Hello, World!
Starting Socket Server...
Socket created with file descriptor: 3
Server is listening for incoming connections...
Waiting for client connection...
Client connected, clientSocketFd: 4
Received data: Message sent by client!
Response sent to client.
Client socket closed.
Waiting for client connection...TCP/IP 套接字
TCP/IP 套接字是最常用的网络通信方式，适用于通过网络进行通信的应用程序。它使用 TCP 协议提供可靠的、面向连接的通信。
Socket server端
#include <iostream>
#include <unistd.h>
#include <arpa/inet.h>
#include <cstring>constexpr const char *SERVER_IP = "127.0.0.1"; // 本地回环地址
constexpr const int SERVER_PORT = 8080; // 端口号void StartTcpServer() {int serverSocketFd = socket(AF_INET, SOCK_STREAM, 0);if (serverSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}sockaddr_in serverAddr;serverAddr.sin_family = AF_INET;serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);serverAddr.sin_port = htons(SERVER_PORT);if (bind(serverSocketFd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {std::cerr << "Error binding socket" << std::endl;close(serverSocketFd);return;}if (listen(serverSocketFd, 5) == -1) {std::cerr << "Error listening for connections" << std::endl;close(serverSocketFd);return;}std::cout << "TCP Server is listening for incoming connections..." << std::endl;while (true) {int clientSocketFd = accept(serverSocketFd, nullptr, nullptr);if (clientSocketFd == -1) {std::cerr << "Error accepting connection" << std::endl;close(serverSocketFd);return;}char buffer[256];ssize_t bytesReceived = recv(clientSocketFd, buffer, sizeof(buffer) - 1, 0);if (bytesReceived > 0) {buffer[bytesReceived] = '\0';std::cout << "Received data: " << buffer << std::endl;const char *response = "OK";send(clientSocketFd, response, strlen(response), 0);}close(clientSocketFd);}close(serverSocketFd);
}int main() {StartTcpServer();return 0;
}
Socket client端
#include <iostream>
#include <unistd.h>
#include <arpa/inet.h>
#include <cstring>constexpr const char *SERVER_IP = "127.0.0.1"; // 本地回环地址
constexpr const int SERVER_PORT = 8080; // 端口号void StartTcpClient() {int clientSocketFd = socket(AF_INET, SOCK_STREAM, 0);if (clientSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}sockaddr_in serverAddr;serverAddr.sin_family = AF_INET;serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);serverAddr.sin_port = htons(SERVER_PORT);if (connect(clientSocketFd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {std::cerr << "Error connecting to server" << std::endl;close(clientSocketFd);return;}const char *message = "Hello from TCP client!";send(clientSocketFd, message, strlen(message), 0);char buffer[256];ssize_t bytesReceived = recv(clientSocketFd, buffer, sizeof(buffer) - 1, 0);if (bytesReceived > 0) {buffer[bytesReceived] = '\0';std::cout << "Received from server: " << buffer << std::endl;}close(clientSocketFd);
}int main() {StartTcpClient();return 0;
}
UDP 套接字
UDP 套接字使用无连接的 UDP 协议，适用于需要快速传输但不需要可靠性的应用（如视频流、在线游戏等）。
Socket server端
#include <iostream>
#include <unistd.h>
#include <arpa/inet.h>
#include <cstring>constexpr const char *SERVER_IP = "127.0.0.1"; // 本地回环地址
constexpr const int SERVER_PORT = 8080; // 端口号void StartUdpServer() {int serverSocketFd = socket(AF_INET, SOCK_DGRAM, 0);if (serverSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}sockaddr_in serverAddr;serverAddr.sin_family = AF_INET;serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);serverAddr.sin_port = htons(SERVER_PORT);if (bind(serverSocketFd, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) == -1) {std::cerr << "Error binding socket" << std::endl;close(serverSocketFd);return;}std::cout << "UDP Server is listening for incoming messages..." << std::endl;while (true) {char buffer[256];sockaddr_in clientAddr;socklen_t clientAddrLen = sizeof(clientAddr);ssize_t bytesReceived = recvfrom(serverSocketFd, buffer, sizeof(buffer) - 1, 0,(struct sockaddr *)&clientAddr, &clientAddrLen);if (bytesReceived > 0) {buffer[bytesReceived] = '\0';std::cout << "Received data: " << buffer << std::endl;// 发送响应给客户端const char *response = "OK";sendto(serverSocketFd, response, strlen(response), 0,(struct sockaddr *)&clientAddr, clientAddrLen);}}close(serverSocketFd);
}int main() {StartUdpServer();return 0;
}
Socket client端
#include <iostream>
#include <unistd.h>
#include <arpa/inet.h>
#include <cstring>constexpr const char *SERVER_IP = "127.0.0.1"; // 本地回环地址
constexpr const int SERVER_PORT = 8080; // 端口号void StartUdpClient() {int clientSocketFd = socket(AF_INET, SOCK_DGRAM, 0);if (clientSocketFd == -1) {std::cerr << "Error creating socket" << std::endl;return;}sockaddr_in serverAddr;serverAddr.sin_family = AF_INET;serverAddr.sin_addr.s_addr = inet_addr(SERVER_IP);serverAddr.sin_port = htons(SERVER_PORT);const char *message = "Hello from UDP client!";sendto(clientSocketFd, message, strlen(message), 0,(struct sockaddr *)&serverAddr, sizeof(serverAddr));char buffer[256];sockaddr_in fromAddr;socklen_t fromAddrLen = sizeof(fromAddr);ssize_t bytesReceived = recvfrom(clientSocketFd, buffer, sizeof(buffer) - 1, 0,(struct sockaddr *)&fromAddr, &fromAddrLen);if (bytesReceived > 0) {buffer[bytesReceived] = '\0';std::cout << "Received from server: " << buffer << std::endl;}close(clientSocketFd);
}int main() {StartUdpClient();return 0;
}