增加libcurl库调用百度API，与原来的的go命令执行调用API两种。libcurl涉及静态链接，考虑使用哪种？

libcurl.c

@@ -0,0 +1,189 @@
+#include "libcurl.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 *curl_get_area(char *ip)
+{
+    char url[256] = { 0 };
+    snprintf(url, sizeof(url), "https://qifu.baidu.com/ip/geo/v1/district?ip=%s", ip);
+    
+    
+    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;
+}
+
+// 函数用于从 cJSON 对象提取字段内容
+void parse_string_field(cJSON *parent, const char *field_name, char *output, size_t max_len) {
+    cJSON *item = cJSON_GetObjectItemCaseSensitive(parent, field_name);
+    if (cJSON_IsString(item) && item->valuestring) {
+        strncpy(output, item->valuestring, max_len - 1);
+        output[max_len - 1] = '\0'; // 确保字符串以 '\0' 结尾
+    } else {
+        output[0] = '\0'; // 如果字段不存在或不是字符串，设置为空字符串
+    }
+}
+
+// 函数用于从 JSON 字符串解析为结构体
+int parse_json_to_struct(const char *json_string, Response *response)
+{
+    if (!response) return -1;
+
+    // 初始化结构体
+    memset(response, 0, sizeof(Response));
+
+    // 解析 JSON 字符串
+    cJSON *root = cJSON_Parse(json_string);
+    if (!root) {
+        fprintf(stderr, "Error parsing JSON: %s\n", cJSON_GetErrorPtr());
+        return -1;
+    }
+
+    // 解析字段
+    parse_string_field(root, "code", response->code, sizeof(response->code));
+    parse_string_field(root, "ip", response->ip, sizeof(response->ip));
+
+    // 如果 code 不是 "Success"，直接返回
+    if (strcmp(response->code, "Success") != 0) {
+        fprintf(stderr, "Invalid code: %s\n", response->code);
+        cJSON_Delete(root);
+        return -1;
+    }
+
+    // 解析 data 对象
+    cJSON *data_item = cJSON_GetObjectItemCaseSensitive(root, "data");
+    if (cJSON_IsObject(data_item)) {
+        parse_string_field(data_item, "continent", response->data.continent, sizeof(response->data.continent));
+        parse_string_field(data_item, "country", response->data.country, sizeof(response->data.country));
+        parse_string_field(data_item, "zipcode", response->data.zipcode, sizeof(response->data.zipcode));
+        parse_string_field(data_item, "owner", response->data.owner, sizeof(response->data.owner));
+        parse_string_field(data_item, "isp", response->data.isp, sizeof(response->data.isp));
+        parse_string_field(data_item, "adcode", response->data.adcode, sizeof(response->data.adcode));
+        parse_string_field(data_item, "prov", response->data.prov, sizeof(response->data.prov));
+        parse_string_field(data_item, "city", response->data.city, sizeof(response->data.city));
+        parse_string_field(data_item, "district", response->data.district, sizeof(response->data.district));
+        parse_string_field(data_item, "region", response->data.region, sizeof(response->data.region));
+    }
+
+    snprintf(response->continent_country, 256, "%s%s", response->data.continent, response->data.country);
+    
+    // 清理 JSON 对象
+    cJSON_Delete(root);
+    return 0;
+}
+
+
+/*
+int main(int argc, char *argv[])
+{
+    char *p = curl_get_area("1.1.1.1");
+    puts(p);
+    
+    
+    // 定义 Response 结构体
+    Response response;
+
+    // 解析 JSON 到结构体
+    if (parse_json_to_struct(p, &response) == 0) {
+        // 输出解析结果
+        printf("Code: %s\n", response.code);
+        printf("IP: %s\n", response.ip);
+        printf("Continent: %s\n", response.data.continent);
+        printf("Country: %s\n", response.data.country);
+        printf("ISP: %s\n", response.data.isp);
+        printf("Region: %s\n", response.data.region);
+    } else {
+        fprintf(stderr, "Failed to parse JSON.\n");
+    }
+
+    
+    free(p);
+}
+*/