4.4 TCP服务器通信

本节我们使用开发板建立一个 tcp 客户端，再去连接指定地址和端口的 tcp 服务端并进行数据通信。打开宏定义 DEMO_SOCKET_CLIENT_SERVER、DEMO_CONNECT_NET；

在开发板连网成功后，创建TCP 服务连接。

static int create_socket_server(int port)
{

char sock_rx[DEMO_SOCK_BUF_SIZE] = {0};
struct sockaddr_in server_addr; // server address information
struct sockaddr_in client_addr; // connector's address information
socklen_t sin_size;
int ret;	
while(1)
{
	if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
	{
    	printf("create socket fail,errno :%d\n",errno);
    	break;
	}
	
	server_addr.sin_family = AF_INET;   
	server_addr.sin_port = htons(port);
	server_addr.sin_addr.s_addr = ((u32) 0x00000000UL);   
	memset(server_addr.sin_zero, '\0', sizeof(server_addr.sin_zero));

	if (bind(server_fd, (struct sockaddr *) &server_addr,
     	sizeof(server_addr)) != 0)
	{
    	printf("bind fail, errno:%d\n",errno);
		break;
 	}
	
	if (listen(server_fd, 1) != 0)
	{
    	printf("listen fail,errno:%d\n",errno);
    	break;
	}

	printf("listen port %d\n", port);
	sin_size = sizeof(client_addr);
	new_fd = accept(server_fd, (struct sockaddr *) &client_addr,
                   &sin_size);
    printf("accept newfd = %d\n",new_fd);
		
    if (new_fd < 0)
    {
          printf("accept fail,errno:%d\n",errno);
          break;
    }
	
	while (1)
	{
    	memset(sock_rx, 0, DEMO_SOCK_BUF_SIZE);
        ret = recv(new_fd, sock_rx, sizeof(sock_rx)-1, 0);
		if(ret == 0)
        {
        	printf("connection disconnect\n");
			break;
        }
		else if(ret < 0)
		{
			printf("receive fail errno:%d\n",errno);
			break;
		}
        else
        {     
        	 sock_rx[ret] = 0;
			 printf("\nReceive %d bytes from %s\n", ret, inet_ntoa(client_addr.sin_addr.s_addr));
			 printf("%s\n",sock_rx);
			 ret = send(new_fd, sock_tx, strlen(sock_tx), 0);
			 if (ret < 0)
			 {
			 	printf("Error occured during sending,errno:%d\n",errno);
				break;
			 }
        }
 	}
	if(new_fd != -1)
	{
		printf("shutting down socket and restaring...\n");
		shutdown(new_fd,0);
		closesocket(new_fd);
	}
}
return 0;

}
程序编译并下载到开发板，串口输入指令指定路由器名称，密码，TCP端口，如：t-server("@snail","ss559550",8080,)，可以看到连接网络后分配到开发板 tcp服务器的ip地址192.168.2.107。

在 PC 上建立一个 tcp client，设置好要连接的TCP服务器IP,端口,即可连接成功。