RT-Thread API参考手册  3.1.1
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tcp 客户端

tcp 客户端例程 更多...

tcp 客户端例程

源码

/*
* Copyright (c) 2006-2018, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
*
*/
/*
* 程序清单:tcp 客户端
*
* 这是一个 tcp 客户端的例程
* 导出 tcpclient 命令到控制终端
* 命令调用格式:tcpclient URL PORT
* URL:服务器地址 PORT::端口号
* 程序功能:接收并显示从服务端发送过来的信息,接收到开头是 'q' 或 'Q' 的信息退出程序
*/
#include <rtthread.h>
#include <sys/socket.h> /* 使用BSD socket,需要包含socket.h头文件 */
#include <netdb.h>
#include <string.h>
#include <finsh.h>
#define BUFSZ 1024
static const char send_data[] = "This is TCP Client from RT-Thread."; /* 发送用到的数据 */
void tcpclient(int argc, char **argv)
{
int ret;
char *recv_data;
struct hostent *host;
int sock, bytes_received;
struct sockaddr_in server_addr;
const char *url;
int port;
if (argc < 3)
{
rt_kprintf("Usage: tcpclient URL PORT\n");
rt_kprintf("Like: tcpclient 192.168.12.44 5000\n");
return ;
}
url = argv[1];
port = strtoul(argv[2], 0, 10);
/* 通过函数入口参数url获得host地址(如果是域名,会做域名解析) */
host = gethostbyname(url);
/* 分配用于存放接收数据的缓冲 */
recv_data = rt_malloc(BUFSZ);
if (recv_data == RT_NULL)
{
rt_kprintf("No memory\n");
return;
}
/* 创建一个socket,类型是SOCKET_STREAM,TCP类型 */
if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
/* 创建socket失败 */
rt_kprintf("Socket error\n");
/* 释放接收缓冲 */
rt_free(recv_data);
return;
}
/* 初始化预连接的服务端地址 */
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(port);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);
rt_memset(&(server_addr.sin_zero), 0, sizeof(server_addr.sin_zero));
/* 连接到服务端 */
if (connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1)
{
/* 连接失败 */
rt_kprintf("Connect fail!\n");
closesocket(sock);
/*释放接收缓冲 */
rt_free(recv_data);
return;
}
while (1)
{
/* 从sock连接中接收最大BUFSZ - 1字节数据 */
bytes_received = recv(sock, recv_data, BUFSZ - 1, 0);
if (bytes_received < 0)
{
/* 接收失败,关闭这个连接 */
closesocket(sock);
rt_kprintf("\nreceived error,close the socket.\r\n");
/* 释放接收缓冲 */
rt_free(recv_data);
break;
}
else if (bytes_received == 0)
{
/* 默认 recv 为阻塞模式,此时收到0认为连接出错,关闭这个连接 */
closesocket(sock);
rt_kprintf("\nreceived error,close the socket.\r\n");
/* 释放接收缓冲 */
rt_free(recv_data);
break;
}
/* 有接收到数据,把末端清零 */
recv_data[bytes_received] = '\0';
if (strncmp(recv_data, "q", 1) == 0 || strncmp(recv_data, "Q", 1) == 0)
{
/* 如果是首字母是q或Q,关闭这个连接 */
closesocket(sock);
rt_kprintf("\n got a 'q' or 'Q',close the socket.\r\n");
/* 释放接收缓冲 */
rt_free(recv_data);
break;
}
else
{
/* 在控制终端显示收到的数据 */
rt_kprintf("\nReceived data = %s ", recv_data);
}
/* 发送数据到sock连接 */
ret = send(sock, send_data, strlen(send_data), 0);
if (ret < 0)
{
/* 接收失败,关闭这个连接 */
closesocket(sock);
rt_kprintf("\nsend error,close the socket.\r\n");
rt_free(recv_data);
break;
}
else if (ret == 0)
{
/* 打印send函数返回值为0的警告信息 */
rt_kprintf("\n Send warning,send function return 0.\r\n");
}
}
return;
}
MSH_CMD_EXPORT(tcpclient, a tcp client sample);