add TCP client send test.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@571 bbd45198-f89e-11dd-88c7-29a3b14d5316

examples/network/tcpsendpacket.c

+#include <rtthread.h>
+#include <lwip/netdb.h> /* 为了解析主机名，需要包含netdb.h头文件 */
+#include <lwip/sockets.h> /* 使用BSD socket，需要包含sockets.h头文件 */
+
+void tcp_senddata(const char* url, int port, int length)
+{
+	struct hostent *host;
+	int sock, err, result, timeout, index;
+	struct sockaddr_in server_addr;
+	rt_uint8_t *buffer_ptr;
+
+	/* 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);
+	/* 创建一个socket，类型是SOCKET_STREAM，TCP类型 */
+	if ((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
+	{
+		/* 创建socket失败 */
+		rt_kprintf("Socket error\n");
+		return;
+	}
+
+	/* 神奇内存 */
+	buffer_ptr = rt_malloc(length);
+	/* 构造发生数据 */
+	for (index = 0; index < length; index ++)
+		buffer_ptr[index] = index & 0xff;
+
+	timeout = 100;
+	/* 设置发送超时时间100ms */
+	lwip_setsockopt(sock, SOL_SOCKET, SO_SNDTIMEO, &timeout, sizeof(timeout));
+	/* 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 */
+	err = connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
+	rt_kprintf("TCP thread connect error code: %d\n", err);
+
+	while(1)
+	{
+		/* 发送数据到sock连接 */
+		result = send(sock, buffer_ptr, length, MSG_DONTWAIT);
+		if(result == -1) //数据发送错误处理
+		{
+			rt_kprintf("TCP thread send error: %d\n", result);
+			lwip_close(sock);	//关闭连接，重新创建连接
+			rt_thread_delay(10);
+			if ((sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == -1)
+				rt_kprintf("TCP Socket error:%d\n",sock);
+			err = connect(sock, (struct sockaddr *)&server_addr, sizeof(struct sockaddr));
+			rt_kprintf("TCP thread connect error code: %d\n", err);
+		}
+	}
+}
+
+#ifdef RT_USING_FINSH
+#include <finsh.h>
+/* 输出tcpclient函数到finsh shell中 */
+FINSH_FUNCTION_EXPORT(tcp_senddata, send a packet through tcp connection);
+#endif
+