How to download a ZIP file from server using cURL in C? - c

Question

I am developing on Linux platform. I am using libcurl and able to receive json response and saving it to file. Below is the code.
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include <string.h>
#define URL "http://www.joes-hardware.com/tools.html"
size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
size_t written;
written = fwrite(ptr, size, nmemb, stream);
return written;
}
int main(void) {
CURL *curl;
FILE *fp;
CURLcode res;
//const char url[] = "http://www.joes-hardware.com/tools.html";
char *url= URL;
char outfilename[FILENAME_MAX] = "./json";
curl = curl_easy_init();
if (curl) {
fp = fopen(outfilename,"wb");
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
fclose(fp);
}
return 0;
}
Now I need to fetch a zip file from the server. Suppose the URL is of the format shown below:
#define URL "https://Server/File.zip"
For such URL, the code is not able to save the zip file.
How to achieve this?

Answer 1

I resolved the issue. The problem was with HTTPS connection. I had to add certificates for HTTPS.
Based on below links:
Can't connect to HTTPS site using cURL. Returns 0 length content instead
Getting no content from a HTTPS connection using CURL
#define CURL_STATICLIB
#include <stdio.h>
#include <curl/curl.h>
#include <curl/types.h>
#include <curl/easy.h>
#include <string.h>
#include <stdlib.h>
#define false 0
size_t write_data(void *ptr, size_t size, size_t nmemb, FILE *stream) {
size_t written;
written = fwrite(ptr, size, nmemb, stream);
return written;
}
int main(void) {
CURL *curl;
FILE *fp;
CURLcode res;
const char url[] = "https://example.com/filename.zip";
const char outfilename[FILENAME_MAX] = "./json.zip";
curl_version_info_data * vinfo = curl_version_info(CURLVERSION_NOW);
if(vinfo->features & CURL_VERSION_SSL){
printf("CURL: SSL enabled\n");
}else{
printf("CURL: SSL not enabled\n");
}
curl = curl_easy_init();
if (curl) {
fp = fopen(outfilename,"wb");
/* Setup the https:// verification options. Note we */
/* do this on all requests as there may be a redirect */
/* from http to https and we still want to verify */
curl_easy_setopt(curl, CURLOPT_URL, url);
curl_easy_setopt(curl, CURLOPT_CAINFO, "./ca-bundle.crt");
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, false);
curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, false);
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_data);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
int i=fclose(fp);
if( i==0)
system("unzip -j json.zip");
}
return 0;
}