CURLOPT_RESOLVER_START_FUNCcurl(easy_setopt CURLOPT_RESOLVER_START_FUNCTION(3)
NAME
CURLOPT_RESOLVER_START_FUNCTION - callback called before a new name re-
solve is started
SYNOPSIS
#include <curl/curl.h>
int resolver_start_cb(void *resolver_state, void *reserved, void *userdata);
CURLcode curl_easy_setopt(CURL *handle,
CURLOPT_RESOLVER_START_FUNCTION,
resolver_start_cb);
DESCRIPTION
Pass a pointer to your callback function, which should match the proto-
type shown above.
This callback function gets called by libcurl every time before a new
resolve request is started.
resolver_state 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 ex-
ample setting up socket callback options.
reserved is reserved.
userdata is the user pointer set with the CURLOPT_RE-
SOLVER_START_DATA(3) option.
The callback must return 0 on success. Returning a non-zero value will
cause the resolve to fail.
DEFAULT
NULL (No callback)
PROTOCOLS
All
EXAMPLE
static int resolver_start_cb(void *resolver_state, void *reserved,
void *userdata)
{
(void)reserved;
printf("Received resolver_state=%p userdata=%p\n",
resolver_state, userdata);
return 0;
}
CURL *curl = curl_easy_init();
if(curl) {
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, "https://example.com");
curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
AVAILABILITY
Added in 7.59.0
RETURN VALUE
Returns CURLE_OK
SEE ALSO
CURLOPT_RESOLVER_START_DATA(3)
libcurl 7.81.0 September 08, CURLOPT_RESOLVER_START_FUNCTION(3)
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