tcpclient_sample.c

/* * 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 1024static 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);