1 /*
2 * Copyright (c) 2006-2023, RT-Thread Development Team
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 *
6 * Change Logs:
7 * Date Author Notes
8 * 2022-01-24 ChungHsuan improve code comments
9 */
10
11 #include <rtthread.h>
12 #include <string.h>
13
14 #if !defined(SAL_USING_POSIX)
15 #error "Please enable SAL_USING_POSIX!"
16 #else
17 #include <sys/time.h>
18 #include <sys/select.h>
19 #endif
20 #include <sys/socket.h> /* socket.h header file is needed when using BSD socket */ /* 使用BSD socket，需要包含socket.h头文件 */
21 #include "netdb.h"
22
23 #define DEBUG_TCP_CLIENT
24
25 #define DBG_TAG "TCP"
26 #ifdef DEBUG_TCP_CLIENT
27 #define DBG_LVL DBG_LOG
28 #else
29 #define DBG_LVL DBG_INFO /* DBG_ERROR */
30 #endif
31 #include <rtdbg.h>
32
33 #include "lwip_demo.h"
34
35 #ifdef SAM_LWIP_EXAMPLE
36
37 #define BUFSZ 1024
38
39 static int started = 0;
40 static int is_running = 0;
41 static char url[256] = "www.baidu.com";
42 static int port = 8080;
43 static const char send_data[] = "This is TCP Client from RT-Thread."; /* The message be sent */ /* 发送用到的数据 */
44
45 /**
46 * @brief This function is for creating a tcp client on RT-Thread
47 */
tcpclient(void * arg)48 static void tcpclient(void *arg)
49 {
50 int ret;
51 char *recv_data;
52 int bytes_received;
53 int sock = -1;
54 struct hostent *host = RT_NULL;
55 struct sockaddr_in server_addr;
56
57 struct timeval timeout;
58 fd_set readset;
59 /* Get host address by parameter url(Domain name resolution if input domain) */
60 /* 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） */
61 host = gethostbyname(url);
62 if (host == RT_NULL)
63 {
64 LOG_E("Get host by name failed!");
65 return;
66 }
67 /* Allocate space for recv_data */
68 /* 分配用于存放接收数据的缓冲 */
69 recv_data = rt_malloc(BUFSZ);
70 if (recv_data == RT_NULL)
71 {
72 LOG_E("No memory");
73 return;
74 }
75 /* Create a socket and set it to SOCK_STREAM(TCP) */
76 /* 创建一个socket，类型是SOCKET_STREAM，TCP类型 */
77 if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1)
78 {
79 /* Failed on creating socket */
80 /* 创建socket失败 */
81 LOG_E("Create socket error");
82 goto __exit;
83 }
84 /* Initialize server side address */
85 /* 初始化预连接的服务端地址 */
86 server_addr.sin_family = AF_INET;
87 server_addr.sin_port = htons(port);
88 server_addr.sin_addr = *((struct in_addr *)host->h_addr);
89 rt_memset(&(server_addr.sin_zero), 0, sizeof(server_addr.sin_zero));
90 /* Connect to server */
91 /* 连接到服务端 */
92 if (connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr)) == -1)
93 {
94 /* Failed on connecting to server */
95 /* 连接失败 */
96 LOG_E("Connect fail!");
97 goto __exit;
98 }
99
100 started = 1;
101 is_running = 1;
102
103 timeout.tv_sec = 3;
104 timeout.tv_usec = 0;
105
106 while (is_running)
107 {
108 FD_ZERO(&readset);
109 FD_SET(sock, &readset);
110
111 /* Wait for read */
112 if (select(sock + 1, &readset, RT_NULL, RT_NULL, &timeout) == 0)
113 continue;
114 /* Receive the maximum size 1024 bytes from socket */
115 /* 从sock连接中接收最大BUFSZ - 1字节数据 */
116 bytes_received = recv(sock, recv_data, BUFSZ - 1, 0);
117 if (bytes_received < 0)
118 {
119 /* Receive failed and close the connection */
120 /* 接收失败，关闭这个连接 */
121 LOG_E("Received error, close the socket.");
122 goto __exit;
123 }
124 else if (bytes_received == 0)
125 {
126 /* Print warning message when recv function returns 0 */
127 /* 打印recv函数返回值为0的警告信息 */
128 LOG_W("Received warning, recv function returns 0.");
129 continue;
130 }
131 else
132 {
133 /* Receive data successfully and append '\0' at the end of message */
134 /* 有接收到数据，把末端清零 */
135 recv_data[bytes_received] = '\0';
136
137 if (rt_strcmp(recv_data, "q") == 0 || rt_strcmp(recv_data, "Q") == 0)
138 {
139 /* If the first letter is 'q' or 'Q', close the connection */
140 /* 如果是首字母是q或Q，关闭这个连接 */
141 LOG_I("Got a 'q' or 'Q', close the socket.");
142 goto __exit;
143 }
144 else
145 {
146 /* Show the message in terminal */
147 /* 在控制终端显示收到的数据 */
148 LOG_D("Received data = %s", recv_data);
149 }
150 }
151 /* Send message to connected socket */
152 /* 发送数据到sock连接 */
153 ret = send(sock, send_data, rt_strlen(send_data), 0);
154 if (ret < 0)
155 {
156 /* Send failed, close the connection */
157 /* 发送失败，关闭这个连接 */
158 LOG_I("send error, close the socket.");
159 goto __exit;
160 }
161 else if (ret == 0)
162 {
163 /* Print warning message when send function returns 0 */
164 /* 打印send函数返回值为0的警告信息 */
165 LOG_W("Send warning, send function returns 0.");
166 }
167 }
168
169 __exit:
170 if (recv_data)
171 {
172 rt_free(recv_data);
173 recv_data = RT_NULL;
174 }
175 if (sock >= 0)
176 {
177 closesocket(sock);
178 sock = -1;
179 }
180 started = 0;
181 is_running = 0;
182 return;
183 }
184
185 /**
186 * @brief Call this function will run LWIP example code.
187 *
188 * @note .
189 *
190 * @param None.
191 *
192 * @return RT_OK or -RT_ERROR.
193 */
194
lwip_demo_run(void)195 rt_err_t lwip_demo_run(void)
196 {
197 rt_thread_t tid;
198
199 tid = rt_thread_create("tcp_client",
200 tcpclient, RT_NULL,
201 2048, RT_THREAD_PRIORITY_MAX/3, 20);
202 if (tid != RT_NULL)
203 {
204 rt_thread_startup(tid);
205 }
206
207 return RT_EOK;
208 }
209 #endif
210
211 /*@}*/
212