'libcurl C++: get cookies with multi interface

I want to get the cookies from a POST request.

curl_global_init(CURL_GLOBAL_DEFAULT);
http_handle = curl_easy_init();
curl_easy_setopt(http_handle, CURLOPT_URL, url);
curl_easy_setopt(http_handle, CURLOPT_COOKIEFILE, "");

curl_easy_perform(http_handle);
curl_easy_getinfo(http_handle, CURLINFO_COOKIELIST, &cookies);

In the case above, cookies are retrieved OK.

I'm trying a similar approach with multi interface. I change the latest two lines above for the following code:

int still_running = 1;
multi_handle = curl_multi_init();
curl_multi_add_handle(multi_handle, http_handle);
do {
    curl_multi_perform(multi_handle, &still_running);
} while (still_running)
struct CURLMsg *msg;
int queued;
do {
    msg = curl_multi_info_read(multi_handle, &queued);
    if ((msg) && (msg->msg == CURLMSG_DONE)) {
        CURL *e = msg->easy_handle;
        CURLcode res = curl_easy_getinfo(e, CURLINFO_COOKIELIST, &cookies);
        // res is OK, but cookies are empty
        long status;
        CURLcode res2 = curl_easy_getinfo(e, CURLINFO_RESPONSE_CODE, &status);
        // res2 is OK, and status gets the status code
    }
} while(msg)

In the code above, I can get for example the response code, but the cookies are empty.

Maybe the multi_info_read does not work to get the cookies? Or could I be missing something?

c++cookieslibcurl


Solution 1:[1]

Please post an minimal reproducible example. The code in the question has a lot of errors and could not be compiled.

My code works well.

#include <iostream>
#include <curl/curl.h>

int main () {
    CURL* http_handle = curl_easy_init();
    curl_easy_setopt(http_handle, CURLOPT_URL, "http://httpbin.org/cookies/set?key=value");
    curl_easy_setopt(http_handle, CURLOPT_COOKIEFILE, "");
    
    int still_running = 1;
    CURLM* multi_handle = curl_multi_init();
    curl_multi_add_handle(multi_handle, http_handle);
    do {
        curl_multi_perform(multi_handle, &still_running);
    } while (still_running);
    struct CURLMsg* msg;
    int queued;
    do {
        msg = curl_multi_info_read(multi_handle, &queued);
        if ((msg) && (msg->msg == CURLMSG_DONE)) {
            CURL* e = msg->easy_handle;
            curl_slist* cookies;
            CURLcode res = curl_easy_getinfo(e, CURLINFO_COOKIELIST, &cookies);
            std::cout << "\nSet-Cookie: " << cookies->data << std::endl;
        }
    } while (msg);
    curl_multi_remove_handle(multi_handle, http_handle);
    curl_multi_cleanup(multi_handle);
    curl_easy_cleanup(http_handle);
    return 0;
}

Output:

% ./a.out               
...
Set-Cookie: httpbin.org FALSE   /   FALSE   0   key value

Sources

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Source: Stack Overflow

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