CURLOPT_RESOLVER_START_FUNCTION - set callback to be called before a new resolve
request is started
int resolver_start_cb(void *resolver_state, void *reserved, void *userdata);
CURLcode curl_easy_setopt(CURL *handle,
Pass a pointer to your callback function, which should match the prototype shown
This callback function gets called by libcurl every time before a new resolve
request is started.
points to a backend-specific resolver state. Currently
only the ares resolver backend has a resolver state. It can be used to set up
any desired option on the ares channel before it's used, for example setting
up socket callback options.
is the user pointer set with the
The callback must return 0 on success. Returning a non-zero value will cause the
resolve to fail.
NULL (No callback)
static int resolver_start_cb(void *resolver_state, void *reserved,
printf("Received resolver_state=%p userdata=%p\n",
CURL *curl = curl_easy_init();
curl_easy_setopt(curl, CURLOPT_RESOLVER_START_FUNCTION, resolver_start_cb);
curl_easy_setopt(curl, CURLOPT_RESOLVER_START_DATA, curl);
curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
Added in 7.59.0