[examples] Create HTTP2 example with http2.golang.org

Intention is to partition the demo into multiple files, so that the
main program is quite easy to follow.
1. connectlib.c: For any URL parsing and TCP connection related stuff
2. sh2lib.c: Convenience functions for HTTP2+TLS. The goal here is to
   expose a simpler API than nghttp2. If most usecases end up being
   served with this library, it could potentially be moved into a separate
   component

examples/protocols/http2_request/main/http2_request_example_main.c

@@ -0,0 +1,199 @@
+/* HTTP2 GET Example using nghttp2
+ 
+   Contacts http2.golang.org and executes the GET/PUT requests. A thin API
+   wrapper on top of nghttp2, to properly demonstrate the interactions.
+
+   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 <stdlib.h>
+#include <sys/time.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+#include "apps/sntp/sntp.h"
+#include "esp_log.h"
+#include "esp_system.h"
+#include "nvs_flash.h"
+
+#include "sh2lib.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 = BIT0;
+
+static const char *TAG = "http2-req";
+
+/* The HTTP/2 server to connect to */
+#define HTTP2_SERVER_URI  "https://http2.golang.org"
+/* A GET request that keeps streaming current time every second */
+#define HTTP2_STREAMING_GET_PATH  "/clockstream"
+/* A PUT request that echoes whatever we had sent to it */
+#define HTTP2_PUT_PATH            "/ECHO"
+
+int handle_get_response(struct sh2lib_handle *handle, const char *data, size_t len, int flags)
+{
+    if (len) {
+        printf("[get-response] %.*s\n", len, data);
+    }
+    if (flags == DATA_RECV_FRAME_COMPLETE) {
+        printf("[get-response] Frame fully received\n");
+    }
+    if (flags == DATA_RECV_RST_STREAM) {
+        printf("[get-response] Stream Closed\n");
+    }
+    return 0;
+}
+
+int handle_echo_response(struct sh2lib_handle *handle, const char *data, size_t len, int flags)
+{
+    if (len) {
+        printf("[echo-response] %.*s\n", len, data);
+    }
+    if (flags == DATA_RECV_FRAME_COMPLETE) {
+        printf("[echo-response] Frame fully received\n");
+    }
+    if (flags == DATA_RECV_RST_STREAM) {
+        printf("[echo-response] Stream Closed\n");
+    }
+    return 0;
+}
+
+int send_put_data(struct sh2lib_handle *handle, char *buf, size_t length, uint32_t *data_flags)
+{
+#define DATA_TO_SEND "Hello World"
+    int copylen = strlen(DATA_TO_SEND);
+    if (copylen < length) {
+        printf("[data-prvd] Sending %d bytes\n", copylen);
+        memcpy(buf, DATA_TO_SEND, copylen);
+    } else {
+        copylen = 0;
+    }
+
+    (*data_flags) |= NGHTTP2_DATA_FLAG_EOF;
+    return copylen;
+}
+
+static void set_time(void)
+{
+    struct timeval tv = {
+        .tv_sec = 1509449941,
+    };
+    struct timezone tz = {
+        0, 0
+    };
+    settimeofday(&tv, &tz);
+
+    /* Start SNTP service */
+    sntp_setoperatingmode(SNTP_OPMODE_POLL);
+    sntp_init();
+}
+
+static void http2_task(void *args)
+{
+    /* Waiting for connection */
+    xEventGroupWaitBits(wifi_event_group, CONNECTED_BIT,
+                        false, true, portMAX_DELAY);
+
+    /* Set current time: proper system time is required for TLS based
+     * certificate verification.
+     */
+    set_time();
+
+    /* HTTP2: one connection multiple requests. Do the TLS/TCP connection first */
+    printf("Connecting to server\n");
+    struct sh2lib_handle hd;
+    if (sh2lib_connect(&hd, HTTP2_SERVER_URI) != 0) {
+        printf("Failed to connect\n");
+        return;
+    }
+    printf("Connection done\n");
+
+    /* HTTP GET  */
+    sh2lib_do_get(&hd, HTTP2_STREAMING_GET_PATH, handle_get_response);
+
+    /* HTTP PUT  */
+    sh2lib_do_put(&hd, HTTP2_PUT_PATH, send_put_data, handle_echo_response);
+
+    while (1) {
+        /* Process HTTP2 send/receive */
+        if (sh2lib_execute(&hd) < 0) {
+            printf("Error in send/receive\n");
+            break;
+        }
+        vTaskDelay(2);
+    }
+
+    sh2lib_free(&hd);
+}
+
+static esp_err_t event_handler(void *ctx, system_event_t *event)
+{
+    switch (event->event_id) {
+    case SYSTEM_EVENT_STA_START:
+        ESP_LOGI(TAG, "SYSTEM_EVENT_STA_START");
+        ESP_ERROR_CHECK(esp_wifi_connect());
+        break;
+    case SYSTEM_EVENT_STA_GOT_IP:
+        ESP_LOGI(TAG, "SYSTEM_EVENT_STA_GOT_IP");
+        ESP_LOGI(TAG, "got ip:%s\n", ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
+        xEventGroupSetBits(wifi_event_group, CONNECTED_BIT);
+        break;
+    case SYSTEM_EVENT_STA_DISCONNECTED:
+        ESP_LOGI(TAG, "SYSTEM_EVENT_STA_DISCONNECTED");
+        ESP_ERROR_CHECK(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() );
+}
+
+void app_main()
+{
+    ESP_ERROR_CHECK( nvs_flash_init() );
+    initialise_wifi();
+
+    xTaskCreate(&http2_task, "http2_task", (1024 * 32), NULL, 5, NULL);
+}