文章目录
1.前言
本篇文章主要是介绍在STM32平台上移植LwIP 2.1.2后,如何使用API进行TCP Client编程。
LwIP主要提供了3种方式编程:
- RAW API:直接访问核心的lwIP栈。优点:不存在数据多次拷贝,占用内存小。缺点:调用RAW API相对比较繁琐,移植性差。
- Netconn API:调用RAW API访问核心的lwIP栈。优点:简化RAW API繁琐的调用。缺点:不通用其他平台API,移植性差。
- Socket API:通过BSD socket风格的接口访问lwIP栈。优点:通用其它平台API,方便程序移植。缺点:存在数据多次拷贝,占用内存。
这3种方式编程的之间的关系如下图所示:
如果想了解如何移植LwIP2.1.2,可以参考这篇文章《【FreeRTOS】基于STM32移植LWIP 2.1.2详细步骤》。本篇文章只是介绍LwIP TCP API如何使用。
2.如何配置LwIP支持Netconn和Socket
需要在lwipopts.h
中,打开LWIP_NETCONN
和LWIP_SOCKET
这2个宏,如下:
/**
* LWIP_NETCONN==1: Enable Netconn API (require to use api_lib.c)
*/
#define LWIP_NETCONN 1
/*
------------------------------------
---------- Socket options ----------
------------------------------------
*/
/**
* LWIP_SOCKET==1: Enable Socket API (require to use sockets.c)
*/
#define LWIP_SOCKET 1
3.使用LwIP Netconn API实现TCP Client
LwIP Netconn API编程主要是3个步骤:
- 初始化netconn并且连接到TCP Server:
netconn_new
、netconn_connect
- 创建一个Task接收消息:
netconn_recv
- 调用
netconn_write
发送消息给TCP Server
具体实现的代码如下:
#include "main.h"
#include "tcp_client.h"
#include "lwip/opt.h"
#include "lwip/tcpip.h"
#include "lwip/sys.h"
#include "lwip/api.h"
#include "lwip/sockets.h"
#include "FreeRTOS.h"
#include "semphr.h"
#include "task.h"
#include "string.h"
#define TCP_CLIENT_TASK_PRIO ( tskIDLE_PRIORITY + 4 )
#define TCP_CLIENT_STACK_SIZE ( configMINIMAL_STACK_SIZE * 4 )
static sys_thread_t lwip_thread;
#define RECV_BUF_SIZE 256
static uint8_t recvBuf[RECV_BUF_SIZE];
static struct netconn *tcp_client_handle = NULL;
void tcp_client_disconnect(void)
{
struct netconn *conn = tcp_client_handle;
if(conn != NULL){
netconn_close(conn);
netconn_delete(conn);
vTaskDelete(lwip_thread.thread_handle);
lwip_thread.thread_handle = NULL;
}
}
int8_t tcp_client_send_data(uint8_t *pData, uint16_t len)
{
int8_t ret = -1;
struct netconn *conn = tcp_client_handle;
if(conn == NULL){
return ret;
}
ret = netconn_write(conn, pData, len, NETCONN_COPY);
if (ret != ERR_OK) {
printf("tcpecho: netconn_write: error \"%s\"\n", lwip_strerr(ret));
}
return ret;
}
static void tcp_client_netconn_thread(void *arg)
{
struct netconn *conn;
struct netbuf *buf;
ip_addr_t DestIPaddr;
err_t err;
LWIP_UNUSED_ARG(arg);
/* Bind to TCP Client port with default IP address */
conn = netconn_new(NETCONN_TCP);
if(conn == NULL){
printf("[TCP Client]netconn_new: invalid conn\r\n");
goto EXIT;
}
netconn_bind(conn, IP4_ADDR_ANY, LOCAL_PORT);
IP4_ADDR( &DestIPaddr, DEST_IP_ADDR0, DEST_IP_ADDR1, DEST_IP_ADDR2, DEST_IP_ADDR3 );
err = netconn_connect(conn, &DestIPaddr, DEST_PORT);
if(err != ERR_OK){
printf("[TCP Client]netconn_connect is fail!!!\r\n");
goto EXIT;
}
tcp_client_handle = conn;
printf("[TCP Client] Connect server is successful!!!\r\n");
do {
err = netconn_recv(conn, &buf);
if (err == ERR_OK) {
uint8_t len = (buf->p->len < RECV_BUF_SIZE) ? buf->p->len : RECV_BUF_SIZE;
MEMCPY(recvBuf, buf->p->payload, len);
recvBuf[len] = '\0';
printf("[Recv Data]%s\r\n", (char *)recvBuf);
}
if (buf != NULL) {
netbuf_delete(buf);
}
} while (1);
EXIT:
vTaskDelete(lwip_thread.thread_handle);
lwip_thread.thread_handle = NULL;
return;
}
void tcp_client_init(void)
{
lwip_thread = sys_thread_new("tcp_client_netconn", tcp_client_netconn_thread, NULL, TCP_CLIENT_STACK_SIZE, TCP_CLIENT_TASK_PRIO);
}
4.使用LwIP Socket API实现TCP Client
LwIP Socket API编程主要是3个步骤:
- 创建socket并且连接到TCP Server:
socket
、connect
- 创建一个Task接收消息:
recv
- 调用
send
发送消息给TCP Server
具体实现的代码如下:
#include "main.h"
#include "tcp_client.h"
#include "lwip/opt.h"
#include "lwip/tcpip.h"
#include "lwip/sys.h"
#include "lwip/api.h"
#include "lwip/sockets.h"
#include "FreeRTOS.h"
#include "semphr.h"
#include "task.h"
#include "string.h"
#define TCP_CLIENT_TASK_PRIO ( tskIDLE_PRIORITY + 4 )
#define TCP_CLIENT_STACK_SIZE ( configMINIMAL_STACK_SIZE * 4 )
static sys_thread_t lwip_thread;
//客户端只需要一个套接字文件描述符,用于和服务器通信
int serverSocket = -1;
void tcp_client_disconnect(void)
{
if(serverSocket != -1){
close(serverSocket);
serverSocket = -1;
vTaskDelete(lwip_thread.thread_handle);
lwip_thread.thread_handle = NULL;
}
}
int8_t tcp_client_send_data(uint8_t *pData, uint16_t len)
{
int8_t ret = -1;
if(serverSocket == -1){
return ret;
}
ret = send(serverSocket, pData, len, 0); //向服务端发送消息
if (ret < 0) {
printf("[TCP Client] Send data is error!!!\r\n");
}
return ret;
}
static void tcp_client_socket_thread(void *arg)
{
//描述服务器的socket
struct sockaddr_in serverAddr;
char recvbuf[100]; //存储 接收到的信息
int iDataNum;
if((serverSocket = socket(AF_INET,SOCK_STREAM,IPPROTO_TCP)) < 0)
{
printf("[TCP Client] Create socket is fail!!!\r\n");
goto EXIT;
}
serverAddr.sin_family = AF_INET;
serverAddr.sin_port = htons(SERVER_PORT);
//指定服务器端的ip,地址:192.168.1.100
//inet_addr()函数,将点分十进制IP转换成网络字节序IP
serverAddr.sin_addr.s_addr = inet_addr("192.168.1.102");
if(connect(serverSocket, (struct sockaddr *)&serverAddr, sizeof(serverAddr)) < 0)
{
printf("[TCP Client] Connect is fail!!!\r\n");
goto EXIT;
}
printf("[TCP Client] Connect server is successful!!!\r\n");
while(1)
{
iDataNum = recv(serverSocket, recvbuf, sizeof(recvbuf), 0); //接收服务端发来的消息
recvbuf[iDataNum] = '\0';
printf("[Recv Data]%s\r\n", recvbuf);
}
EXIT:
vTaskDelete(lwip_thread.thread_handle);
lwip_thread.thread_handle = NULL;
return;
}
void tcp_client_init(void)
{
lwip_thread = sys_thread_new("tcp_client_socket", tcp_client_socket_thread, NULL, TCP_CLIENT_STACK_SIZE, TCP_CLIENT_TASK_PRIO);
}
5.验证测试
最后验证测试成功,如下:
6.资料下载地址
移植成功的完整代码下载地址如下:
https://download.csdn.net/download/ZHONGCAI0901/13126159