linux c 写一个tcp服务端代码，监听13400端口

以下是一个简单的C语言TCP服务端代码，可以监听13400端口：

#include <stdio.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <string.h>

int main() {
    int server_socket, client_socket;
    struct sockaddr_in server_address, client_address;
    char buffer[1024];

    // 创建socket
    server_socket = socket(AF_INET, SOCK_STREAM, 0);
    if (server_socket == -1) {
        printf("Error: Failed to create socket.\n");
        exit(1);
    }

    // 设置server_address
    server_address.sin_family = AF_INET;
    server_address.sin_addr.s_addr = INADDR_ANY;
    server_address.sin_port = htons(13400);

    // 绑定socket
    if (bind(server_socket, (struct sockaddr*) &server_address, sizeof(server_address)) == -1) {
        printf("Error: Failed to bind.\n");
        exit(2);
    }

    // 监听socket
    if (listen(server_socket, 5) == -1) {
        printf("Error: Failed to listen.\n");
        exit(3);
    }

    printf("Server is listening on port 13400...\n");

    // 接受客户端连接
    socklen_t client_address_size = sizeof(client_address);
    client_socket = accept(server_socket, (struct sockaddr*) &client_address, &client_address_size);
    if (client_socket == -1) {
        printf("Error: Failed to accept connection.\n");
        exit(4);
    }

    printf("Client connected.\n");

    // 从客户端接收数据并回复
    while (1) {
        memset(buffer, 0, sizeof(buffer));
        int bytes_received = recv(client_socket, buffer, sizeof(buffer), 0);
        if (bytes_received == -1) {
            printf("Error: Failed to receive data.\n");
            exit(5);
        } else if (bytes_received == 0) {
            printf("Client disconnected.\n");
            break;
        }

        printf("Received: %s\n", buffer);

        int bytes_sent = send(client_socket, buffer, strlen(buffer), 0);
        if (bytes_sent == -1) {
            printf("Error: Failed to send data.\n");
            exit(6);
        }
    }

    // 关闭sockets
    close(client_socket);
    close(server_socket);

    return 0;
}

这段代码创建一个TCP socket，然后绑定到13400端口上，通过listen函数开始监听。当客户端连接时，accept函数会返回客户端的socket，然后服务端就可以开始和客户端通信了。在这个例子中，服务端会接收客户端发来的消息，并将消息原封不动地回复给客户端。关闭连接时，需要关闭两个socket：客户端socket和服务端socket。