基于TCP的半双工网络编程实践

首先我们先了解一下什么是半双工通信？

半双工数据传输允许数据在两个方向上传输，但是在某一时刻，只允许数据在一个方向上传输，它实际上是一种切换方向的单工通信。

TCP服务端代码：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <netdb.h> 
#include <netinet/in.h> 
#include <stdint.h>     
#include <sys/socket.h>  
#include <sys/types.h> 
#include <unistd.h>  #define PORT 8100 /* 打印错误信息 */
void error()
{perror("Socket Creation Failed");exit(EXIT_FAILURE);
}int main()
{uint32_t sockfd,conn;  char server_msg[10000],client_msg[10000];  struct sockaddr_in server_addr,client_addr;  /* 创建流式套接字 */if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){error();  }/* 服务端绑定地址和端口 */bzero(&server_addr, sizeof(server_addr));server_addr.sin_family = AF_INET;   server_addr.sin_port = htons(PORT); server_addr.sin_addr.s_addr = htonl(INADDR_ANY);printf("Server is running...\n");/* 绑定socket到服务端 */if (bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0){error();  /// If binding is unsuccessful}/* 监听客户端，监听的数量上限，我们这里设置为5 */listen(sockfd, 5);printf("Server is listening...\n");/* 当服务端发现有新的连接请求，服务端创建一个socket描述符响应accept，用来发送和接收数据 */conn = accept(sockfd, (struct sockaddr *)NULL, NULL);printf("Server is connected...\n");while (1){bzero(&server_msg, sizeof(server_msg));bzero(&client_msg, sizeof(client_msg));/* 发送消息 */printf("\nEnter message here: ");fgets(server_msg, 10000, stdin);send(conn, server_msg, strlen(server_msg) + 1, 0);/* 接收消息 */recv(conn, client_msg, sizeof(client_msg), 0);printf("\nClient Message: %s\n", client_msg);}/* 关闭socket */close(sockfd);printf("Server is offline...\n");return 0;
}

服务端运行状态：

TCP客户端代码：

#include <stdio.h>  
#include <stdlib.h>  
#include <string.h>
#include <netdb.h> 
#include <netinet/in.h>  
#include <stdint.h>       
#include <sys/socket.h> 
#include <sys/types.h>  
#include <unistd.h>  #define PORT 8100  void error()
{perror("Socket Creation Failed");exit(EXIT_FAILURE);
}int main()
{uint32_t sockfd;struct sockaddr_in server_addr; char serverResponse[10000],clientResponse[10000]; /* 客户端创建socket */if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0){error();}bzero(&server_addr, sizeof(server_addr));server_addr.sin_family = AF_INET;server_addr.sin_port = htons(PORT);server_addr.sin_addr.s_addr = htonl(INADDR_ANY);printf("Client is running...\n");/* 连接服务端 */connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));printf("Client is connected...\n");while (1){bzero(&serverResponse, sizeof(serverResponse));bzero(&clientResponse, sizeof(clientResponse));/* 接收消息 */recv(sockfd, serverResponse, sizeof(serverResponse), 0);printf("\nServer message: %s \n", serverResponse);/* 发送消息 */printf("\nEnter message here: ");fgets(clientResponse, 10000, stdin);send(sockfd, clientResponse, strlen(clientResponse) + 1, 0);}/* 关闭socket */close(sockfd);printf("Client is offline...\n");return 0;
}

客户端运行状态：