ESP8266之TCP_Server
模块：esp-01s
SDK版本:ESP8266_RTOS_SDK-3.0
开发环境：wsl+vscode
功能模块：wifi，tcp_server
之前写过关于esp8266的tcp_client通信，这次我们来学习tcp_server通信。开始之前依然建议熟悉socket编程基础，这里推荐这篇文章https://www.cnblogs.com/skynet/archive/2010/12/12/1903949.html
本文使用SDK里面的tcp_server例程,不过我删去了IPV6的部分代码。经测试client不能重连，所以需要我们添加一行代码。
（后来发现是socket编程端口复用的问题，待我学习一下再修改程序）
我们来理清一下思路：
1.首先初始化wifi（STA或者AP模式都可以）
2.然后建立tcp server
建立tcp server有如下过程：
a.使用socket()建立序列化双向可靠的字节流
b.使用bind()绑定socket与端口
c.使用listen()监听
d.使用accept()接收客户端连接请求
f.使用recv()接收数据
下面就开始吧
#include <string.h>
#include <sys/param.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_wifi.h"
#include "esp_event_loop.h"
#include "esp_log.h"
#include "nvs_flash.h"
#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include <lwip/netdb.h>
#define EXAMPLE_WIFI_SSID "weiecn" //要连接的wifi名
#define EXAMPLE_WIFI_PASS "weiecn.com"//要连接的wifi密码
#define PORT CONFIG_EXAMPLE_PORT
/* FreeRTOS event group to signal when we are connected & ready to make a request */
static EventGroupHandle_t wifi_event_group;
const int IPV4_GOTIP_BIT = BIT0;
static const char *TAG = "example";
static esp_err_t event_handler(void *ctx, system_event_t *event)
{
switch (event->event_id) {
case SYSTEM_EVENT_STA_START://STA模式
esp_wifi_connect();
ESP_LOGI(TAG, "SYSTEM_EVENT_STA_START");
break;
case SYSTEM_EVENT_STA_GOT_IP://获取IP
xEventGroupSetBits(wifi_event_group, IPV4_GOTIP_BIT);
ESP_LOGI(TAG, "SYSTEM_EVENT_STA_GOT_IP");
break;
case SYSTEM_EVENT_STA_DISCONNECTED://断开事件触发重连
esp_wifi_connect();
xEventGroupClearBits(wifi_event_group, IPV4_GOTIP_BIT);
break;
default:
break;
}
return ESP_OK;
}
//wifi STA初始化
static void initialise_wifi(void)
{
tcpip_adapter_init();
wifi_event_group = xEventGroupCreate();
ESP_ERROR_CHECK( esp_event_loop_init(event_handler, NULL) );
wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
ESP_ERROR_CHECK( esp_wifi_init(&cfg) );
ESP_ERROR_CHECK( esp_wifi_set_storage(WIFI_STORAGE_RAM) );
wifi_config_t wifi_config = {
.sta = {
.ssid = EXAMPLE_WIFI_SSID,//wifi名
.password = EXAMPLE_WIFI_PASS,//wifi密码
},
};
ESP_LOGI(TAG, "Setting WiFi configuration SSID %s...", wifi_config.sta.ssid);
ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );
ESP_ERROR_CHECK( esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config) );
ESP_ERROR_CHECK( esp_wifi_start() );
}
static void tcp_server_task(void *pvParameters)
{
char rx_buffer[128];//设置接收缓冲
char addr_str[128];//
int addr_family;
int ip_protocol;
while (1) {
struct sockaddr_in destAddr;//存储server地址结构
destAddr.sin_addr.s_addr = htonl(INADDR_ANY);//本地地址，并转换为网络字节序（long int）
destAddr.sin_family = AF_INET;//协议
destAddr.sin_port = htons(60000);//端口，转换为网络字节序（short int）
addr_family = AF_INET;
ip_protocol = IPPROTO_IP;
inet_ntoa_r(destAddr.sin_addr, addr_str, sizeof(addr_str) - 1);
int listen_sock = socket(addr_family, SOCK_STREAM, ip_protocol);//建立socket连接
if (listen_sock < 0) {
ESP_LOGE(TAG, "Unable to create socket: errno %d", errno);
break;
}
ESP_LOGI(TAG, "Socket created");
int err = bind(listen_sock, (struct sockaddr *)&destAddr, sizeof(destAddr));//将socket与主机端口绑定
if (err != 0) {
ESP_LOGE(TAG, "Socket unable to bind: errno %d", errno);
break;
}
ESP_LOGI(TAG, "Socket binded");
err = listen(listen_sock, 1);//监听
if (err != 0) {
ESP_LOGE(TAG, "Error occured during listen: errno %d", errno);
break;
}
ESP_LOGI(TAG, "Socket listening");
struct sockaddr_in sourceAddr;
uint addrLen = sizeof(sourceAddr);
int sock = accept(listen_sock, (struct sockaddr *)&sourceAddr, &addrLen);//服务器接收client连接请求
if (sock < 0) {
ESP_LOGE(TAG, "Unable to accept connection: errno %d", errno);
break;
}
ESP_LOGI(TAG, "Socket accepted");
while (1) {
int len = recv(sock, rx_buffer, sizeof(rx_buffer) - 1, 0);//接收数据
// Error occured during receiving
if (len < 0) {
ESP_LOGE(TAG, "recv failed: errno %d", errno);
break;
}
// Connection closed
else if (len == 0) {
ESP_LOGI(TAG, "Connection closed");
break;
}
// Data received
else {
// Get the sender's ip address as string
if (sourceAddr.sin_family == PF_INET) {
inet_ntoa_r(((struct sockaddr_in *)&sourceAddr)->sin_addr.s_addr, addr_str, sizeof(addr_str) - 1);
}
rx_buffer[len] = 0; // Null-terminate whatever we received and treat like a string
ESP_LOGI(TAG, "Received %d bytes from %s:", len, addr_str);
ESP_LOGI(TAG, "%s", rx_buffer);
int err = send(sock, rx_buffer, len, 0);//发送数据
if (err < 0) {
ESP_LOGE(TAG, "Error occured during sending: errno %d", errno);
break;
}
}
}
if (sock != -1) {
ESP_LOGE(TAG, "Shutting down socket and restarting...");
shutdown(sock, 0);
close(sock);//关闭accept
close(listen_sock);
}
}
vTaskDelete(NULL);
}
void app_main()
{
ESP_ERROR_CHECK( nvs_flash_init() );
initialise_wifi();
//wait_for_ip();
xTaskCreate(tcp_server_task, "tcp_server", 4096, NULL, 5, NULL);
}