CURLOPT_IPRESOLVE(3) Library Functions Manual CURLOPT_IPRESOLVE(3)
NAME
CURLOPT_IPRESOLVE - IP protocol version to use
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_IPRESOLVE, long resolve);
DESCRIPTION
Allows an application to select what kind of IP addresses to use when
establishing a connection or choosing one from the connection pool. This
is interesting when using hostnames that resolve to more than one IP
family.
If the URL provided for a transfer contains a numerical IP version as a
host name, this option does not override or prohibit libcurl from using
that IP version.
Available values for this option are:
CURL_IPRESOLVE_WHATEVER
Default, can use addresses of all IP versions that your system
allows.
CURL_IPRESOLVE_V4
Uses only IPv4 addresses.
CURL_IPRESOLVE_V6
Uses only IPv6 addresses.
DEFAULT
CURL_IPRESOLVE_WHATEVER
PROTOCOLS
This functionality affects all supported protocols
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
/* of all addresses example.com resolves to, only IPv6 ones are used */
curl_easy_setopt(curl, CURLOPT_IPRESOLVE, (long)CURL_IPRESOLVE_V6);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}
AVAILABILITY
Added in curl 7.10.8
RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred,
see libcurl-errors(3).
SEE ALSO
CURLOPT_HTTP_VERSION(3), CURLOPT_RESOLVE(3), CURLOPT_SSLVERSION(3)
libcurl 2026-07-12 CURLOPT_IPRESOLVE(3)
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