ESP32（4）TCP通信

本章重点讲解 lwIP 的 Socket接口如何配置 TCP客户端，并在此基础上实现收发功能。

TCP Client 连接流程

在实现 TCP 协议之前，用户需要按照以下步骤配置结构体 sockaddr_in 的成员变量，以便建立 TCPClient 连接：
①：配置 ESP32-S3 设备连接网络（必须的，因为 WiFi 是无线通信，所以需搭建通信桥梁）。
②：将 sin_family 设置为 AF_INET，表示使用 IPv4 网络协议。
③：设置 sin_port 为所需的端口号，例如 8080。
④：设置 sin_addr.s_addr 为远程 IP 地址。
⑤：调用函数 Socket 创建 Socket 连接。请注意，该函数的第二个参数指定连接类型。SOCK_STREAM 表示 TCP 连接，而 SOCK_DGRAM 表示 UDP 连接。
⑥：调用函数 connect 连接远程 IP 地址。
⑦：调用适当的收发函数来接收或发送数据。
通过遵循这些步骤，用户可成功地配置并建立TCPClient连接，以实现数据的发送和接收。

TCP-Client

/** SPDX-FileCopyrightText: 2010-2022 Espressif Systems (Shanghai) CO LTD** SPDX-License-Identifier: CC0-1.0*/#include <stdio.h>
#include <string.h>
#include <sys/param.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_chip_info.h"
#include "esp_eap_client.h"
#include "esp_smartconfig.h"
#include "esp_flash.h"
#include "nvs_flash.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_event.h"
#include "esp_wifi.h"
#include "esp_netif.h"
#include "esp_mac.h"#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include <lwip/netdb.h>static const char *TAG = "network";
void tcp_client_task(void *parm);//=============================================================smart config===============================================================
static EventGroupHandle_t s_wifi_event_group;static const int CONNECTED_BIT = BIT0;
static const int ESPTOUCH_DONE_BIT = BIT1;static void smartconfig_task(void * parm);static void event_handler(void* arg, esp_event_base_t event_base,int32_t event_id, void* event_data)
{if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {xTaskCreate(smartconfig_task, "smartconfig_task", 4096, NULL, 3, NULL);} else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {esp_wifi_connect();xEventGroupClearBits(s_wifi_event_group, CONNECTED_BIT);} else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {xEventGroupSetBits(s_wifi_event_group, CONNECTED_BIT);} else if (event_base == SC_EVENT && event_id == SC_EVENT_SCAN_DONE) {ESP_LOGI(TAG, "Scan done");} else if (event_base == SC_EVENT && event_id == SC_EVENT_FOUND_CHANNEL) {ESP_LOGI(TAG, "Found channel");} else if (event_base == SC_EVENT && event_id == SC_EVENT_GOT_SSID_PSWD) {ESP_LOGI(TAG, "Got SSID and password");smartconfig_event_got_ssid_pswd_t *evt = (smartconfig_event_got_ssid_pswd_t *)event_data;wifi_config_t wifi_config;uint8_t ssid[33] = { 0 };uint8_t password[65] = { 0 };uint8_t rvd_data[33] = { 0 };bzero(&wifi_config, sizeof(wifi_config_t));memcpy(wifi_config.sta.ssid, evt->ssid, sizeof(wifi_config.sta.ssid));memcpy(wifi_config.sta.password, evt->password, sizeof(wifi_config.sta.password));#ifdef CONFIG_SET_MAC_ADDRESS_OF_TARGET_APwifi_config.sta.bssid_set = evt->bssid_set;if (wifi_config.sta.bssid_set == true) {ESP_LOGI(TAG, "Set MAC address of target AP: "MACSTR" ", MAC2STR(evt->bssid));memcpy(wifi_config.sta.bssid, evt->bssid, sizeof(wifi_config.sta.bssid));}
#endifmemcpy(ssid, evt->ssid, sizeof(evt->ssid));memcpy(password, evt->password, sizeof(evt->password));ESP_LOGI(TAG, "SSID:%s", ssid);ESP_LOGI(TAG, "PASSWORD:%s", password);if (evt->type == SC_TYPE_ESPTOUCH_V2) {ESP_ERROR_CHECK( esp_smartconfig_get_rvd_data(rvd_data, sizeof(rvd_data)) );ESP_LOGI(TAG, "RVD_DATA:");for (int i=0; i<33; i++) {printf("%02x ", rvd_data[i]);}printf("\n");}ESP_ERROR_CHECK( esp_wifi_disconnect() );ESP_ERROR_CHECK( esp_wifi_set_config(WIFI_IF_STA, &wifi_config) );esp_wifi_connect();} else if (event_base == SC_EVENT && event_id == SC_EVENT_SEND_ACK_DONE) {xEventGroupSetBits(s_wifi_event_group, ESPTOUCH_DONE_BIT);}
}static void initialise_wifi(void)
{ESP_ERROR_CHECK(esp_netif_init());s_wifi_event_group = xEventGroupCreate();ESP_ERROR_CHECK(esp_event_loop_create_default());esp_netif_t *sta_netif = esp_netif_create_default_wifi_sta();assert(sta_netif);wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();ESP_ERROR_CHECK( esp_wifi_init(&cfg) );ESP_ERROR_CHECK( esp_event_handler_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL) );ESP_ERROR_CHECK( esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL) );ESP_ERROR_CHECK( esp_event_handler_register(SC_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL) );ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );ESP_ERROR_CHECK( esp_wifi_start() );
}static void smartconfig_task(void * parm)
{EventBits_t uxBits;ESP_ERROR_CHECK( esp_smartconfig_set_type(SC_TYPE_ESPTOUCH) );smartconfig_start_config_t cfg = SMARTCONFIG_START_CONFIG_DEFAULT();ESP_ERROR_CHECK( esp_smartconfig_start(&cfg) );while (1) {uxBits = xEventGroupWaitBits(s_wifi_event_group, CONNECTED_BIT | ESPTOUCH_DONE_BIT, true, false, portMAX_DELAY);if(uxBits & CONNECTED_BIT) {ESP_LOGI(TAG, "WiFi Connected to ap");}if(uxBits & ESPTOUCH_DONE_BIT) {ESP_LOGI(TAG, "smartconfig over");esp_smartconfig_stop();xTaskCreate(tcp_client_task, "tcp_client", 4096, NULL, 5, NULL);vTaskDelete(NULL);}}
}
//======================================================tcp client=================================================================
#define CONFIG_EXAMPLE_IPV4 #if defined(CONFIG_EXAMPLE_IPV4)
#define HOST_IP_ADDR "192.168.4.178"
#elif defined(CONFIG_EXAMPLE_SOCKET_IP_INPUT_STDIN)
#define HOST_IP_ADDR ""
#endif#define PORT 8080static const char *payload = "Message from ESP32 ";void tcp_client_task(void *parm)
{char rx_buffer[128];char host_ip[] = HOST_IP_ADDR;int addr_family = 0;int ip_protocol = 0;while (1) {
#if defined(CONFIG_EXAMPLE_IPV4)struct sockaddr_in dest_addr;inet_pton(AF_INET, host_ip, &dest_addr.sin_addr);dest_addr.sin_family = AF_INET;dest_addr.sin_port = htons(PORT);addr_family = AF_INET;ip_protocol = IPPROTO_IP;
#elif defined(CONFIG_EXAMPLE_SOCKET_IP_INPUT_STDIN)struct sockaddr_storage dest_addr = { 0 };ESP_ERROR_CHECK(get_addr_from_stdin(PORT, SOCK_STREAM, &ip_protocol, &addr_family, &dest_addr));
#endifint sock =  socket(addr_family, SOCK_STREAM, ip_protocol);if (sock < 0) {ESP_LOGE(TAG, "Unable to create socket: errno %d", errno);}ESP_LOGI(TAG, "Socket created, connecting to %s:%d", host_ip, PORT);int err = connect(sock, (struct sockaddr *)&dest_addr, sizeof(dest_addr));if (err != 0) {ESP_LOGE(TAG, "Socket unable to connect: errno %d", errno);}ESP_LOGI(TAG, "Successfully connected");while (1) {int err = send(sock, payload, strlen(payload), 0);if (err < 0) {ESP_LOGE(TAG, "Error occurred during sending: errno %d", errno);}int len = recv(sock, rx_buffer, sizeof(rx_buffer) - 1, 0);// Error occurred during receivingif (len < 0) {ESP_LOGE(TAG, "recv failed: errno %d", errno);}// Data receivedelse {rx_buffer[len] = 0; // Null-terminate whatever we received and treat like a stringESP_LOGI(TAG, "Received %d bytes from %s:", len, host_ip);ESP_LOGI(TAG, "%s", rx_buffer);}}if (sock != -1) {ESP_LOGE(TAG, "Shutting down socket and restarting...");shutdown(sock, 0);close(sock);}}
}//===================================================================================================================================void app_main(void)
{printf("Hello world!\n");/* Print chip information */esp_chip_info_t chip_info;uint32_t flash_size;esp_chip_info(&chip_info);printf("This is %s chip with %d CPU core(s), %s%s%s%s, ",CONFIG_IDF_TARGET,chip_info.cores,(chip_info.features & CHIP_FEATURE_WIFI_BGN) ? "WiFi/" : "",(chip_info.features & CHIP_FEATURE_BT) ? "BT" : "",(chip_info.features & CHIP_FEATURE_BLE) ? "BLE" : "",(chip_info.features & CHIP_FEATURE_IEEE802154) ? ", 802.15.4 (Zigbee/Thread)" : "");unsigned major_rev = chip_info.revision / 100;unsigned minor_rev = chip_info.revision % 100;printf("silicon revision v%d.%d, ", major_rev, minor_rev);if(esp_flash_get_size(NULL, &flash_size) != ESP_OK) {printf("Get flash size failed");return;}printf("%" PRIu32 "MB %s flash\n", flash_size / (uint32_t)(1024 * 1024),(chip_info.features & CHIP_FEATURE_EMB_FLASH) ? "embedded" : "external");printf("Minimum free heap size: %" PRIu32 " bytes\n", esp_get_minimum_free_heap_size());// Initialize NVSesp_err_t ret = nvs_flash_init();if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {ESP_ERROR_CHECK(nvs_flash_erase());ret = nvs_flash_init();}ESP_ERROR_CHECK(ret);//initinitialise_wifi();while(1) {vTaskDelay(1000);}
}

注意，当smart config成功以后我们才创建tcp_client_task，保证流程同步，否则tcp无法成功连接。

测试结果：

TCP-Server

/** SPDX-FileCopyrightText: 2010-2022 Espressif Systems (Shanghai) CO LTD** SPDX-License-Identifier: CC0-1.0*/#include <stdio.h>
#include <string.h>
#include <sys/param.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_chip_info.h"
#include "esp_eap_client.h"
#include "esp_smartconfig.h"
#include "esp_flash.h"
#include "nvs_flash.h"
#include "esp_system.h"
#include "esp_log.h"
#include "esp_event.h"
#include "esp_wifi.h"
#include "esp_netif.h"
#include "esp_mac.h"#include "lwip/err.h"
#include "lwip/sockets.h"
#include "lwip/sys.h"
#include <lwip/netdb.h>static const char *TAG = "network";
void tcp_client_task(void *parm);//=============================================================smart config===============================================================
static EventGroupHandle_t s_wifi_event_group;static const int CONNECTED_BIT = BIT0;
static const int ESPTOUCH_DONE_BIT = BIT1;static void smartconfig_task(void * parm);static void event_handler(void* arg, esp_event_base_t event_base,int32_t event_id, void* event_data)
{if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_START) {xTaskCreate(smartconfig_task, "smartconfig_task", 4096, NULL, 3, NULL);} else if (event_base == WIFI_EVENT && event_id == WIFI_EVENT_STA_DISCONNECTED) {esp_wifi_connect();xEventGroupClearBits(s_wifi_event_group, CONNECTED_BIT);} else if (event_base == IP_EVENT && event_id == IP_EVENT_STA_GOT_IP) {xEventGroupSetBits(s_wifi_event_group, CONNECTED_BIT);} else if (event_base == SC_EVENT && event_id == SC_EVENT_SCAN_DONE) {ESP_LOGI(TAG, "Scan done");} else if (event_base == SC_EVENT && event_id == SC_EVENT_FOUND_CHANNEL) {ESP_LOGI(TAG, "Found channel");} else if (event_base == SC_EVENT && event_id == SC_EVENT_GOT_SSID_PSWD) {ESP_LOGI(TAG, "Got SSID and password");smartconfig_event_got_ssid_pswd_t *evt = (smartconfig_event_got_ssid_pswd_t *)event_data;wifi_config_t wifi_config;uint8_t ssid[33] = { 0 };uint8_t password[65] = { 0 };uint8_t rvd_data[33] = { 0 };bzero(&wifi_config, sizeof(wifi_config_t));memcpy(wifi_config.sta.ssid, evt->ssid, sizeof(wifi_config.sta.ssid));memcpy(wifi_config.sta.password, evt->password, sizeof(wifi_config.sta.password));#ifdef CONFIG_SET_MAC_ADDRESS_OF_TARGET_APwifi_config.sta.bssid_set = evt->bssid_set;if (wifi_config.sta.bssid_set == true) {ESP_LOGI(TAG, "Set MAC address of target AP: "MACSTR" ", MAC2STR(evt->bssid));memcpy(wifi_config.sta.bssid, evt->bssid, sizeof(wifi_config.sta.bssid));}
#endifmemcpy(ssid, evt->ssid, sizeof(evt->ssid));memcpy(password, evt->password, sizeof(evt->password));ESP_LOGI(TAG, "SSID:%s", ssid);ESP_LOGI(TAG, "PASSWORD:%s", password);if (evt->type == SC_TYPE_ESPTOUCH_V2) {ESP_ERROR_CHECK( esp_smartconfig_get_rvd_data(rvd_data, sizeof(rvd_data)) );ESP_LOGI(TAG, "RVD_DATA:");for (int i=0; i<33; i++) {printf("%02x ", rvd_data[i]);}printf("\n");}ESP_ERROR_CHECK( esp_wifi_disconnect() );ESP_ERROR_CHECK( esp_wifi_set_config(WIFI_IF_STA, &wifi_config) );esp_wifi_connect();} else if (event_base == SC_EVENT && event_id == SC_EVENT_SEND_ACK_DONE) {xEventGroupSetBits(s_wifi_event_group, ESPTOUCH_DONE_BIT);}
}static void initialise_wifi(void)
{ESP_ERROR_CHECK(esp_netif_init());s_wifi_event_group = xEventGroupCreate();ESP_ERROR_CHECK(esp_event_loop_create_default());esp_netif_t *sta_netif = esp_netif_create_default_wifi_sta();assert(sta_netif);wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();ESP_ERROR_CHECK( esp_wifi_init(&cfg) );ESP_ERROR_CHECK( esp_event_handler_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL) );ESP_ERROR_CHECK( esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &event_handler, NULL) );ESP_ERROR_CHECK( esp_event_handler_register(SC_EVENT, ESP_EVENT_ANY_ID, &event_handler, NULL) );ESP_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );ESP_ERROR_CHECK( esp_wifi_start() );
}static void smartconfig_task(void * parm)
{EventBits_t uxBits;ESP_ERROR_CHECK( esp_smartconfig_set_type(SC_TYPE_ESPTOUCH) );smartconfig_start_config_t cfg = SMARTCONFIG_START_CONFIG_DEFAULT();ESP_ERROR_CHECK( esp_smartconfig_start(&cfg) );while (1) {uxBits = xEventGroupWaitBits(s_wifi_event_group, CONNECTED_BIT | ESPTOUCH_DONE_BIT, true, false, portMAX_DELAY);if(uxBits & CONNECTED_BIT) {ESP_LOGI(TAG, "WiFi Connected to ap");}if(uxBits & ESPTOUCH_DONE_BIT) {ESP_LOGI(TAG, "smartconfig over");esp_smartconfig_stop();vTaskDelete(NULL);}}
}
//======================================================tcp server=================================================================
#define CONFIG_EXAMPLE_IPV4#define PORT                        8080
#define KEEPALIVE_IDLE              300
#define KEEPALIVE_INTERVAL          30
#define KEEPALIVE_COUNT             3static void do_retransmit(const int sock)
{int len;char rx_buffer[128];do {len = recv(sock, rx_buffer, sizeof(rx_buffer) - 1, 0);if (len < 0) {ESP_LOGE(TAG, "Error occurred during receiving: errno %d", errno);} else if (len == 0) {ESP_LOGW(TAG, "Connection closed");} else {rx_buffer[len] = 0; // Null-terminate whatever is received and treat it like a stringESP_LOGI(TAG, "Received %d bytes: %s", len, rx_buffer);// send() can return less bytes than supplied length.// Walk-around for robust implementation.int to_write = len;while (to_write > 0) {int written = send(sock, rx_buffer + (len - to_write), to_write, 0);if (written < 0) {ESP_LOGE(TAG, "Error occurred during sending: errno %d", errno);// Failed to retransmit, giving upreturn;}to_write -= written;}}} while (len > 0);
}static void tcp_server_task(void *pvParameters)
{char addr_str[128];int addr_family = (int)pvParameters;int ip_protocol = 0;int keepAlive = 1;int keepIdle = KEEPALIVE_IDLE;int keepInterval = KEEPALIVE_INTERVAL;int keepCount = KEEPALIVE_COUNT;struct sockaddr_storage dest_addr;#ifdef CONFIG_EXAMPLE_IPV4if (addr_family == AF_INET) {struct sockaddr_in *dest_addr_ip4 = (struct sockaddr_in *)&dest_addr;dest_addr_ip4->sin_addr.s_addr = htonl(INADDR_ANY);dest_addr_ip4->sin_family = AF_INET;dest_addr_ip4->sin_port = htons(PORT);ip_protocol = IPPROTO_IP;}
#endif
#ifdef CONFIG_EXAMPLE_IPV6if (addr_family == AF_INET6) {struct sockaddr_in6 *dest_addr_ip6 = (struct sockaddr_in6 *)&dest_addr;bzero(&dest_addr_ip6->sin6_addr.un, sizeof(dest_addr_ip6->sin6_addr.un));dest_addr_ip6->sin6_family = AF_INET6;dest_addr_ip6->sin6_port = htons(PORT);ip_protocol = IPPROTO_IPV6;}
#endifint listen_sock = socket(addr_family, SOCK_STREAM, ip_protocol);if (listen_sock < 0) {ESP_LOGE(TAG, "Unable to create socket: errno %d", errno);vTaskDelete(NULL);return;}int opt = 1;setsockopt(listen_sock, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
#if defined(CONFIG_EXAMPLE_IPV4) && defined(CONFIG_EXAMPLE_IPV6)// Note that by default IPV6 binds to both protocols, it is must be disabled// if both protocols used at the same time (used in CI)setsockopt(listen_sock, IPPROTO_IPV6, IPV6_V6ONLY, &opt, sizeof(opt));
#endifESP_LOGI(TAG, "Socket created");int err = bind(listen_sock, (struct sockaddr *)&dest_addr, sizeof(dest_addr));if (err != 0) {ESP_LOGE(TAG, "Socket unable to bind: errno %d", errno);ESP_LOGE(TAG, "IPPROTO: %d", addr_family);goto CLEAN_UP;}ESP_LOGI(TAG, "Socket bound, port %d", PORT);err = listen(listen_sock, 1);if (err != 0) {ESP_LOGE(TAG, "Error occurred during listen: errno %d", errno);goto CLEAN_UP;}while (1) {ESP_LOGI(TAG, "Socket listening");struct sockaddr_storage source_addr; // Large enough for both IPv4 or IPv6socklen_t addr_len = sizeof(source_addr);int sock = accept(listen_sock, (struct sockaddr *)&source_addr, &addr_len);if (sock < 0) {ESP_LOGE(TAG, "Unable to accept connection: errno %d", errno);break;}// Set tcp keepalive optionsetsockopt(sock, SOL_SOCKET, SO_KEEPALIVE, &keepAlive, sizeof(int));setsockopt(sock, IPPROTO_TCP, TCP_KEEPIDLE, &keepIdle, sizeof(int));setsockopt(sock, IPPROTO_TCP, TCP_KEEPINTVL, &keepInterval, sizeof(int));setsockopt(sock, IPPROTO_TCP, TCP_KEEPCNT, &keepCount, sizeof(int));// Convert ip address to string
#ifdef CONFIG_EXAMPLE_IPV4if (source_addr.ss_family == PF_INET) {inet_ntoa_r(((struct sockaddr_in *)&source_addr)->sin_addr, addr_str, sizeof(addr_str) - 1);}
#endif
#ifdef CONFIG_EXAMPLE_IPV6if (source_addr.ss_family == PF_INET6) {inet6_ntoa_r(((struct sockaddr_in6 *)&source_addr)->sin6_addr, addr_str, sizeof(addr_str) - 1);}
#endifESP_LOGI(TAG, "Socket accepted ip address: %s", addr_str);do_retransmit(sock);shutdown(sock, 0);close(sock);}CLEAN_UP:close(listen_sock);vTaskDelete(NULL);
}//===================================================================================================================================void app_main(void)
{printf("Hello world!\n");/* Print chip information */esp_chip_info_t chip_info;uint32_t flash_size;esp_chip_info(&chip_info);printf("This is %s chip with %d CPU core(s), %s%s%s%s, ",CONFIG_IDF_TARGET,chip_info.cores,(chip_info.features & CHIP_FEATURE_WIFI_BGN) ? "WiFi/" : "",(chip_info.features & CHIP_FEATURE_BT) ? "BT" : "",(chip_info.features & CHIP_FEATURE_BLE) ? "BLE" : "",(chip_info.features & CHIP_FEATURE_IEEE802154) ? ", 802.15.4 (Zigbee/Thread)" : "");unsigned major_rev = chip_info.revision / 100;unsigned minor_rev = chip_info.revision % 100;printf("silicon revision v%d.%d, ", major_rev, minor_rev);if(esp_flash_get_size(NULL, &flash_size) != ESP_OK) {printf("Get flash size failed");return;}printf("%" PRIu32 "MB %s flash\n", flash_size / (uint32_t)(1024 * 1024),(chip_info.features & CHIP_FEATURE_EMB_FLASH) ? "embedded" : "external");printf("Minimum free heap size: %" PRIu32 " bytes\n", esp_get_minimum_free_heap_size());// Initialize NVSesp_err_t ret = nvs_flash_init();if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {ESP_ERROR_CHECK(nvs_flash_erase());ret = nvs_flash_init();}ESP_ERROR_CHECK(ret);//initinitialise_wifi();#ifdef CONFIG_EXAMPLE_IPV4xTaskCreate(tcp_server_task, "tcp_server", 4096, (void*)AF_INET, 5, NULL);#endif#ifdef CONFIG_EXAMPLE_IPV6xTaskCreate(tcp_server_task, "tcp_server", 4096, (void*)AF_INET6, 5, NULL);#endifwhile(1) {vTaskDelay(1000);}
}

测试：测试类比client操作。