#include "ip.h"



struct MemoryStruct {
    char *memory;
    size_t size;
};

static size_t WriteMemoryCallback(void *contents, size_t size, size_t nmemb, void *userp)
{
    size_t realsize = size * nmemb;
    struct MemoryStruct *mem = (struct MemoryStruct *)userp;

    // 注意这里根据每次被调用获得的数据重新动态分配缓存区的大小
    char *ptr = realloc(mem->memory, mem->size + realsize + 1);
    if (ptr == NULL) {
        /* 内存不足！ */
        printf("not enough memory (realloc returned NULL)\n");
        return 0;
    }

    mem->memory = ptr;
    memcpy(&(mem->memory[mem->size]), contents, realsize);
    mem->size += realsize;
    mem->memory[mem->size] = 0;

    return realsize;
}

// 获取公网IP
char *GET_PUBLIC_IP(char *URL)
{
    CURL *curl_handle;
    CURLcode res;

    struct curl_slist *headers = NULL;
    struct MemoryStruct chunk;

    chunk.memory = malloc(1);   /* 将根据上述再分配的需要增长 */
    chunk.size = 0;             /* 此时没有数据 */

    curl_global_init(CURL_GLOBAL_ALL);

    /* 初始化curl会话 */
    curl_handle = curl_easy_init();

    char *p = NULL;
    char *buff;

    p = strstr(URL, "-H");
    if (p) {

        buff = (char *)alloca(p - URL + 1);
        if (buff == NULL)
            perror("out of memory.");

        memset(buff, 0, p - URL + 1);
        memcpy(buff, URL, (int)(p - URL - 1));

        // 赋值header值
        headers = curl_slist_append(headers, p + 3);

        // 设置header
        curl_easy_setopt(curl_handle, CURLOPT_HTTPHEADER, headers);
        curl_easy_setopt(curl_handle, CURLOPT_URL, buff);

    } else {
        /* 指定要获取的URL */
        curl_easy_setopt(curl_handle, CURLOPT_URL, URL);

    }

    /* 将所有数据发送到此函数  */
    //对于同一次阻塞的curl_easy_perform而言，在写完获取的数据之前，会多次调用 WriteMemoryCallback
    curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, WriteMemoryCallback);

    /* 将"chunk"结构传递给回调函数 */
    curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, (void *)&chunk);

    curl_easy_setopt(curl_handle, CURLOPT_USERAGENT, "libcurl-agent/1.0");

    //对于同一次阻塞的curl_easy_perform而言，在写完获取的数据之前，会多次调用 WriteMemoryCallback
    res = curl_easy_perform(curl_handle);

    if (res != CURLE_OK) {
        fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
    } else {
        //printf("%lu bytes retrieved\n", (unsigned long)chunk.size);
        //printf("%s", chunk.memory);
        ;
    }

    curl_easy_cleanup(curl_handle);
    curl_global_cleanup();

    return chunk.memory;
}