examples: Add CoAP server demo

Test CoAP protocol server

examples/24_coap_server/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 := coap_server
+
+include $(IDF_PATH)/make/project.mk
+

examples/24_coap_server/main/Kconfig.projbuild

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+menu "Example Configuration"
+
+config LOCAL_PORT_NUMBER
+    int "Local port number"
+    range 0 65535
+    default 5683
+    help
+        Local port number for the example to use.
+
+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.
+
+endmenu

examples/24_coap_server/main/coap_server.c

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+/* CoAP server Example
+
+   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 "coap_server.h"
+
+#include <string.h>
+
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "freertos/event_groups.h"
+
+#include "esp_log.h"
+#include "esp_wifi.h"
+#include "esp_event_loop.h"
+
+#include "nvs_flash.h"
+#include <sys/socket.h>
+
+#include "coap_config.h"
+#include "resource.h"
+#include "coap.h"
+
+
+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 static int CONNECTED_BIT = BIT0;
+
+const static char *TAG = "CoAP_demo";
+
+static coap_async_state_t *async = NULL;
+
+static void
+send_async_response(coap_context_t *ctx, const coap_endpoint_t *local_if)
+{
+	coap_pdu_t *response;
+	unsigned char buf[3];
+	const char* response_data     = "Hello World!";
+	size_t size = sizeof(coap_hdr_t) + 20;
+	response = coap_pdu_init(async->flags & COAP_MESSAGE_CON, COAP_RESPONSE_CODE(205), 0, size);
+	response->hdr->id = coap_new_message_id(ctx);
+	if (async->tokenlen)
+		coap_add_token(response, async->tokenlen, async->token);
+	coap_add_option(response, COAP_OPTION_CONTENT_TYPE, coap_encode_var_bytes(buf, COAP_MEDIATYPE_TEXT_PLAIN), buf);
+	coap_add_data  (response, strlen(response_data), (unsigned char *)response_data);
+
+	if (coap_send(ctx, local_if, &async->peer, response) == COAP_INVALID_TID) {
+
+	}
+	coap_delete_pdu(response);
+	coap_async_state_t *tmp;
+	coap_remove_async(ctx, async->id, &tmp);
+	coap_free_async(async);
+	async = NULL;
+}
+
+/*
+ * The resource handler
+ */
+static void
+async_handler(coap_context_t *ctx, struct coap_resource_t *resource,
+              const coap_endpoint_t *local_interface, coap_address_t *peer,
+              coap_pdu_t *request, str *token, coap_pdu_t *response)
+{
+	async = coap_register_async(ctx, peer, request, COAP_ASYNC_SEPARATE | COAP_ASYNC_CONFIRM, (void*)"no data");
+}
+
+static void coap_demo_thread(void *p)
+{
+	coap_context_t*  ctx = NULL;
+	coap_address_t   serv_addr;
+	coap_resource_t* resource = NULL;
+	fd_set           readfds;
+	struct timeval tv;
+	int flags = 0;
+	/* Prepare the CoAP server socket */
+	coap_address_init(&serv_addr);
+	serv_addr.addr.sin.sin_family      = AF_INET;
+	serv_addr.addr.sin.sin_addr.s_addr = INADDR_ANY;
+	serv_addr.addr.sin.sin_port        = htons(COAP_DEFAULT_PORT);
+	ctx                                = coap_new_context(&serv_addr);
+	if (ctx) {
+		flags = fcntl(ctx->sockfd, F_GETFL, 0);
+		fcntl(ctx->sockfd, F_SETFL, flags|O_NONBLOCK);
+
+		tv.tv_usec = COAP_DEFAULT_TIME_USEC;
+		tv.tv_sec = COAP_DEFAULT_TIME_SEC;
+		/* Initialize the resource */
+		resource = coap_resource_init((unsigned char *)"Espressif", 9, 0);
+		if (resource){
+			coap_register_handler(resource, COAP_REQUEST_GET, async_handler);
+			coap_add_resource(ctx, resource);
+			/*For incoming connections*/
+			for (;;) {
+				FD_ZERO(&readfds);
+				FD_CLR( ctx->sockfd, &readfds);
+				FD_SET( ctx->sockfd, &readfds);
+
+				int result = select( FD_SETSIZE, &readfds, 0, 0, &tv );
+				if (result > 0){
+					if (FD_ISSET( ctx->sockfd, &readfds ))
+						coap_read(ctx);
+				} else if (result < 0){
+					break;
+				} else {
+					printf("select timeout\n");
+				}
+
+				if (async)
+					send_async_response(ctx, ctx->endpoint);
+			}
+		}
+
+		coap_free_context(ctx);
+	}
+
+	vTaskDelete(NULL);
+}
+
+static void coap_server_init(void)
+{
+    int ret = pdPASS;
+    xTaskHandle coap_handle = NULL;
+
+    ret = xTaskCreate(coap_demo_thread,
+                      COAP_DEMO_THREAD_NAME,
+                      COAP_DEMO_THREAD_STACK_WORDS,
+                      NULL,
+                      COAP_DEMO_THREAD_PRORIOTY,
+                      &coap_handle);
+
+    if (ret != pdPASS)  {
+        ESP_LOGI(TAG, "create thread %s failed", COAP_DEMO_THREAD_NAME);
+    }
+}
+
+static esp_err_t wifi_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);
+        coap_server_init();
+        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 wifi_conn_init(void)
+{
+    tcpip_adapter_init();
+    wifi_event_group = xEventGroupCreate();
+    ESP_ERROR_CHECK( esp_event_loop_init(wifi_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_ERROR_CHECK( esp_wifi_set_mode(WIFI_MODE_STA) );
+    ESP_ERROR_CHECK( esp_wifi_set_config(WIFI_IF_STA, &wifi_config) );
+
+    ESP_ERROR_CHECK( esp_wifi_start() );
+}
+
+void app_main(void)
+{
+    nvs_flash_init();
+    wifi_conn_init();
+}

examples/24_coap_server/main/coap_server.h

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+/* CoAP server Example
+
+   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.
+*/
+
+#ifndef _COAP_SERVER_H_
+#define _COAP_SERVER_H_
+
+#include <sdkconfig.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
+
+#define COAP_DEMO_THREAD_NAME        "CoAP_demo"
+#define COAP_DEMO_THREAD_STACK_WORDS 10240
+#define COAP_DEMO_THREAD_PRORIOTY    8
+
+/* The examples use local port number of 5683 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 OPENSSL_DEMO_TARGET_TCP_PORT 5683
+*/
+#define COAP_DEFAULT_PORT CONFIG_LOCAL_PORT_NUMBER
+#define COAP_DEFAULT_TIME_SEC 5
+#define COAP_DEFAULT_TIME_USEC 0
+
+#endif
+

examples/24_coap_server/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.)
+