Article Directory
1 Introduction
This article mainly introduces porting on the STM32 platformLwIP 2.1.2Later, how to use API for TCP Client programming.
LwIP mainly provides 3 ways to program:
- RAW API : Directly access the core lwIP stack. Advantages : There is no multiple copies of data and small memory usage. Disadvantages : calling RAW API is relatively cumbersome and poor in portability.
- Netconn API : Call RAW API to access the core lwIP stack. Advantages : simplify the tedious call of RAW API. Disadvantages : Not common to other platform APIs, poor portability.
- Socket API : Access the lwIP stack through a BSD socket style interface. Advantages : Common other platform APIs, convenient for program transplantation. Disadvantages : There are multiple copies of data, which takes up memory.
The relationship between these 3 ways of programming is shown in the figure below:
If you want to know how to transplant LwIP 2.1.2, you can refer to this article "[FreeRTOS] Detailed steps for transplanting LWIP 2.1.2 based on STM32" . This article only introduces how to use LwIP TCP API.
2. How to configure LwIP to support Netconn and Socket
Need lwipopts.hto open LWIP_NETCONNand LWIP_SOCKETthese 2 macros in the middle , as follows:
/**
* 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. Use LwIP Netconn API to implement TCP Client
LwIP Netconn API programming mainly consists of 3 steps:
- Initialize netconn and connect to TCP Server:
netconn_new、netconn_connect - Create a Task to receive messages:
netconn_recv - Call to
netconn_writesend a message to TCP Server
The specific implementation code is as follows:
#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. Use LwIP Socket API to implement TCP Client
LwIP Socket API programming mainly consists of 3 steps:
- Create socket and connect to TCP Server:
socket、connect - Create a Task to receive messages:
recv - Call to
sendsend a message to TCP Server
The specific implementation code is as follows:
#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. Verification test
Finally, the verification test is successful, as follows:
6. Data download address
The complete code download address for successful transplantation is as follows:
https://download.csdn.net/download/ZHONGCAI0901/13126159