feat(examples): Add http request example

examples/protocols/http_request/Makefile

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+#
+# This is a project Makefile. It is assumed the directory this Makefile resides in is a
+# project subdirectory.
+#
+
+PROJECT_NAME := http-request
+
+include $(IDF_PATH)/make/project.mk
+

examples/protocols/http_request/README.md

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+# HTTP Request Example
+
+Uses a POSIX socket to make a very simple HTTP request.
+
+See the README.md file in the upper level 'examples' directory for more information about examples.

examples/protocols/http_request/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+config WIFI_SSID
+    string "WiFi SSID"
+    default "myssid"
+    help
+        SSID (network name) for the example to connect to.
+
+config WIFI_PASSWORD
+    string "WiFi Password"
+    default "mypassword"
+    help
+        WiFi password (WPA or WPA2) for the example to use.
+
+        Can be left blank if the network has no security set.
+
+endmenu

examples/protocols/http_request/main/component.mk

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+#
+# "main" pseudo-component makefile.
+#
+# (Uses default behaviour of compiling all source files in directory, adding 'include' to include path.)

examples/protocols/http_request/main/http_request_example_main.c

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+/* HTTP GET Example using plain POSIX sockets
+
+   This example code is in the Public Domain (or CC0 licensed, at your option.)
+
+   Unless required by applicable law or agreed to in writing, this
+   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
+   CONDITIONS OF ANY KIND, either express or implied.
+*/
+#include <string.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"
+#include "lwip/dns.h"
+
+/* The examples use simple WiFi configuration that you can set via
+   'make menuconfig'.
+
+   If you'd rather not, just change the below entries to strings with
+   the config you want - ie #define EXAMPLE_WIFI_SSID "mywifissid"
+*/
+#define EXAMPLE_WIFI_SSID CONFIG_WIFI_SSID
+#define EXAMPLE_WIFI_PASS CONFIG_WIFI_PASSWORD
+
+/* FreeRTOS event group to signal when we are connected & ready to make a request */
+static EventGroupHandle_t wifi_event_group;
+
+/* The event group allows multiple bits for each event,
+   but we only care about one event - are we connected
+   to the AP with an IP? */
+const int CONNECTED_BIT = 1>>0;
+
+/* Constants that aren't configurable in menuconfig */
+#define WEB_SERVER "example.com"
+#define WEB_PORT 80
+#define WEB_URL "http://example.com/"
+
+static const char *TAG = "example";
+
+static const char *REQUEST = "GET " WEB_URL " HTTP/1.0\r\n"
+    "Host: "WEB_SERVER"\r\n"
+    "User-Agent: esp-idf/1.0 esp32\r\n"
+    "\r\n";
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch(event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        esp_wifi_connect();
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        /* This is a workaround as ESP32 WiFi libs don't currently
+           auto-reassociate. */
+        esp_wifi_connect();
+        xEventGroupClearBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    default:
+        break;
+    }
+    return ESP_OK;
+}
+
+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,
+            .password = EXAMPLE_WIFI_PASS,
+        },
+    };
+    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 http_get_task(void *pvParameters)
+{
+    const struct addrinfo hints = {
+        .ai_family = AF_INET,
+        .ai_socktype = SOCK_STREAM,
+    };
+    struct addrinfo *res;
+    struct in_addr *addr;
+    int s, r;
+    char recv_buf[64];
+
+    while(1) {
+        /* Wait for the callback to set the CONNECTED_BIT in the
+           event group.
+        */
+        xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT,
+                            false, true, portMAX_DELAY);
+        ESP_LOGI(TAG, "Connected to AP");
+
+        int err = getaddrinfo(WEB_SERVER, "80", &hints, &res);
+
+        if(err != 0 || res == NULL) {
+            ESP_LOGE(TAG, "DNS lookup failed err=%d res=%p", err, res);
+            vTaskDelay(1000 / portTICK_PERIOD_MS);
+            continue;
+        }
+
+        /* Code to print the resolved IP.
+
+           Note: inet_ntoa is non-reentrant, look at ipaddr_ntoa_r for "real" code */
+        addr = &((struct sockaddr_in *)res->ai_addr)->sin_addr;
+        ESP_LOGI(TAG, "DNS lookup succeeded. IP=%s", inet_ntoa(*addr));
+
+        s = socket(res->ai_family, res->ai_socktype, 0);
+        if(s < 0) {
+            ESP_LOGE(TAG, "... Failed to allocate socket.");
+            freeaddrinfo(res);
+            vTaskDelay(1000 / portTICK_PERIOD_MS);
+            continue;
+        }
+        ESP_LOGI(TAG, "... allocated socket");
+
+        if(connect(s, res->ai_addr, res->ai_addrlen) != 0) {
+            ESP_LOGE(TAG, "... socket connect failed errno=%d", errno);
+            close(s);
+            freeaddrinfo(res);
+            vTaskDelay(4000 / portTICK_PERIOD_MS);
+            continue;
+        }
+
+        ESP_LOGI(TAG, "... connected");
+        freeaddrinfo(res);
+
+        if (write(s, REQUEST, strlen(REQUEST)) < 0) {
+            ESP_LOGE(TAG, "... socket send failed");
+            close(s);
+            vTaskDelay(4000 / portTICK_PERIOD_MS);
+            continue;
+        }
+        ESP_LOGI(TAG, "... socket send success");
+
+        struct timeval receiving_timeout;
+        receiving_timeout.tv_sec = 5;
+        receiving_timeout.tv_usec = 0;
+        if (setsockopt(s, SOL_SOCKET, SO_RCVTIMEO, &receiving_timeout,
+                sizeof(receiving_timeout)) < 0) {
+            ESP_LOGE(TAG, "... failed to set socket receiving timeout");
+            close(s);
+            vTaskDelay(4000 / portTICK_PERIOD_MS);
+            continue;
+        }
+        ESP_LOGI(TAG, "... set socket receiving timeout success");
+
+        /* Read HTTP response */
+        do {
+            bzero(recv_buf, sizeof(recv_buf));
+            r = read(s, recv_buf, sizeof(recv_buf)-1);
+            for(int i = 0; i < r; i++) {
+                putchar(recv_buf[i]);
+            }
+        } while(r > 0);
+
+        ESP_LOGI(TAG, "... done reading from socket. Last read return=%d errno=%d\r\n", r, errno);
+        close(s);
+        for(int countdown = 10; countdown >= 0; countdown--) {
+            ESP_LOGI(TAG, "%d... ", countdown);
+            vTaskDelay(1000 / portTICK_PERIOD_MS);
+        }
+        ESP_LOGI(TAG, "Starting again!");
+    }
+}
+
+/******************************************************************************
+ * FunctionName : user_rf_cal_sector_set
+ * Description  : SDK just reversed 4 sectors, used for rf init data and paramters.
+ *                We add this function to force users to set rf cal sector, since
+ *                we don't know which sector is free in user's application.
+ *                sector map for last several sectors : ABCCC
+ *                A : rf cal
+ *                B : rf init data
+ *                C : sdk parameters
+ * Parameters   : none
+ * Returns      : rf cal sector
+*******************************************************************************/
+uint32_t user_rf_cal_sector_set(void)
+{
+    flash_size_map size_map = system_get_flash_size_map();
+    uint32_t rf_cal_sec = 0;
+
+    switch (size_map) {
+        case FLASH_SIZE_4M_MAP_256_256:
+            rf_cal_sec = 128 - 5;
+            break;
+
+        case FLASH_SIZE_8M_MAP_512_512:
+            rf_cal_sec = 256 - 5;
+            break;
+
+        case FLASH_SIZE_16M_MAP_512_512:
+        case FLASH_SIZE_16M_MAP_1024_1024:
+            rf_cal_sec = 512 - 5;
+            break;
+
+        case FLASH_SIZE_32M_MAP_512_512:
+        case FLASH_SIZE_32M_MAP_1024_1024:
+            rf_cal_sec = 1024 - 5;
+            break;
+
+        case FLASH_SIZE_64M_MAP_1024_1024:
+            rf_cal_sec = 2048 - 5;
+            break;
+
+        case FLASH_SIZE_128M_MAP_1024_1024:
+            rf_cal_sec = 4096 - 5;
+            break;
+
+        default:
+            rf_cal_sec = 0;
+            break;
+    }
+
+    return rf_cal_sec;
+}
+
+void user_init()
+{
+    ESP_ERROR_CHECK( nvs_flash_init() );
+    initialise_wifi();
+    xTaskCreate(&http_get_task, "http_get_task", 4096, NULL, 5, NULL);
+}