ms_process_create("iotpi_coap", (ms_addr_t)0x08040000, 65536, 4096, 9, 0 , 0, MS_NULL, MS_NULL, MS_NULL);

/**
 * WiFi AP list.
 */
static const ms_esp_at_net_ap_t ap_list[] = {
    { "EOS-00000F",    "123456789" }, // Spirit 1 的 Wi-Fi AP SSID 与密码 
};

/* 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 <string.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>

#include "coap.h"

/* Set this to 9 to get verbose logging from within libcoap */
/* If want to change log level num to open log, don't forget to enlarge coap_example_task size*/
#define COAP_LOGGING_LEVEL 0

// test 资源对应的变量
static char test_data[100];
static int test_data_len = 0;

// test 资源的 GET 请求处理函数
static void
hnd_test_get(coap_context_t *ctx, coap_resource_t *resource,
             coap_session_t *session,
             coap_pdu_t *request, coap_binary_t *token,
             coap_string_t *query, coap_pdu_t *response)
{
    // 将 test_data 变量的内容增加到响应中
    coap_add_data_blocked_response(resource, session, request, response, token,
                                   COAP_MEDIATYPE_TEXT_PLAIN, 0,
                                   (size_t)test_data_len,
                                   (const u_char *)test_data);
}

// test 资源的 PUT 请求处理函数
static void
hnd_test_put(coap_context_t *ctx,
             coap_resource_t *resource,
             coap_session_t *session,
             coap_pdu_t *request,
             coap_binary_t *token,
             coap_string_t *query,
             coap_pdu_t *response)
{
    size_t size;
    unsigned char *data;

    // 通知观察者
    coap_resource_notify_observers(resource, NULL);

    // 设置响应代码
    if (strcmp (test_data, "no data") == 0) {
        response->code = COAP_RESPONSE_CODE(201);
    } else {
        response->code = COAP_RESPONSE_CODE(204);
    }

    // 从请求中获得数据
    (void)coap_get_data(request, &size, &data);

    // 用获得的数据设置 test_data 变量
    if (size == 0) {      /* re-init */
        snprintf(test_data, sizeof(test_data), "no data");
        test_data_len = strlen(test_data);
    } else {
        test_data_len = size > sizeof (test_data) ? sizeof (test_data) : size;
        memcpy (test_data, data, test_data_len);
    }
}

// test 资源的 DELETE 请求处理函数
static void
hnd_test_delete(coap_context_t *ctx,
                  coap_resource_t *resource,
                  coap_session_t *session,
                  coap_pdu_t *request,
                  coap_binary_t *token,
                  coap_string_t *query,
                  coap_pdu_t *response)
{
    // 通知观察者
    coap_resource_notify_observers(resource, NULL);

    // 将 test_data 变量设置为 "no data"
    snprintf(test_data, sizeof(test_data), "no data");
    test_data_len = strlen(test_data);

    // 设置响应代码
    response->code = COAP_RESPONSE_CODE(202);
}

int main(int argc, char **argv)
{
    coap_context_t *ctx = NULL;         // CoAP 协议栈上下文
    coap_address_t serv_addr;           // 多种 sockaddr 的抽象
    coap_resource_t *resource = NULL;   // CoAP 资源指针

    // 初始化 test_data 变量内容
    snprintf(test_data, sizeof(test_data), "no data");
    test_data_len = strlen(test_data);

    // 设置日志级别
    coap_set_log_level(COAP_LOGGING_LEVEL);

    while (1) {
        coap_endpoint_t *ep_udp = NULL;
        coap_endpoint_t *ep_tcp = NULL;
        unsigned wait_ms;

        // 创建一个新的 CoAP 上下文
        ctx = coap_new_context(NULL);
        if (!ctx) {
           continue;
        }

        // 准备 CoAP 服务器套接字
        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);
        // 创建 UDP 通信端点
        ep_udp = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_UDP); //Add IPv4 endpoint
        if (!ep_udp) {
           goto clean_up;
        }
        // 创建 TCP 通信端点
        ep_tcp = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_TCP);
        if (!ep_tcp) {
           goto clean_up;
        }

        // 初始化 test 资源
        resource = coap_resource_init(coap_make_str_const("test"), 0);
        if (!resource) {
           goto clean_up;
        }
		// 设置 test 资源的 GET 请求处理函数
        coap_register_handler(resource, COAP_REQUEST_GET, hnd_test_get);     
		// 设置 test 资源的 PUT 请求处理函数
        coap_register_handler(resource, COAP_REQUEST_PUT, hnd_test_put);     
		// 设置 test 资源的 DELETE 请求处理函数
        coap_register_handler(resource, COAP_REQUEST_DELETE, hnd_test_delete);  
        // 设置 test 资源是否可观察
        //（如果资源是可观察的，并且客户端在请求包中设置了 COAP_OPTION_OBSERVE， 
        // 当资源的状态发生变化时，调用 coap_resource_notify_observers()，
        // 将发送一个 Observer 响应）
        coap_resource_set_get_observable(resource, 1);

        // CoAP 上下文加入 test 资源
        coap_add_resource(ctx, resource);

        // 设置等待时间
        wait_ms = COAP_RESOURCE_CHECK_TIME * 1000;

        while (1) {
            // CoAP 协议栈 IO 处理，传入等待时间，返回前消耗的时间
            int result = coap_io_process(ctx, wait_ms);
            if (result < 0) {
                // 出错
                break;
            } else if (result && (unsigned)result < wait_ms) {
                // 如果消耗时间少于等待时间，则修改等待时间 wait_ms
                wait_ms -= result;
            }
            if (result) {
                // 如果消耗时间大于等于等待时间，则重置等待时间 wait_ms
                wait_ms = COAP_RESOURCE_CHECK_TIME * 1000;
            }
        }
    }
clean_up:
    // 释放 CoAP 上下文
    coap_free_context(ctx);
    // 清理 libcoap
    coap_cleanup();
    return 0;
}