added some code

wrote some code to test some functionallity

src/client_backend/connect.cpp

@@ -32,4 +32,50 @@ int connect_to_srv(const char*url,char*out,int max_len, bool ignore_insecure) {
     }
     return 2;
 }
+size_t write_callback(void* contents, size_t size, size_t nmemb, void* userp) {
+    size_t totalSize = size * nmemb;
+    FILE* file = (FILE*)userp;
+    if (file) {
+        fwrite(contents, 1, totalSize, file);
+    }
+    return totalSize;
+}
+
+int download_file_from_srv(const char* url, const char* outputFileName) {
+    //use curl to download a file from a server
+
+    CURL* curl;
+    CURLcode res;
+    FILE* output_file;
+
+    curl = curl_easy_init();
+    if (!curl) {
+        return 1;
+    }
+
+    // Set the URL to download
+    curl_easy_setopt(curl, CURLOPT_URL, url);
+
+    // Create a file to write the downloaded data
+    output_file = fopen(outputFileName, "wb");
+    if (!output_file) {
+        curl_easy_cleanup(curl);
+        return 1;
+    }
+
+    // Set the write callback function
+    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
+    curl_easy_setopt(curl, CURLOPT_WRITEDATA, output_file);
+
+    // Perform the download
+    res = curl_easy_perform(curl);
+    if (res != CURLE_OK) {
+        return 1;
+    }
+    // Cleanup and close the file
+    curl_easy_cleanup(curl);
+    fclose(output_file);
+
+    return 0;
+}
 #endif