curl / libcurl / API / curl_easy_setopt / CURLOPT_IPRESOLVE

CURLOPT_IPRESOLVE explained

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 result;   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, CURL_IPRESOLVE_V6);     result = curl_easy_perform(curl);     curl_easy_cleanup(curl);   } }

History

CURL_IPRESOLVE_* macros became long types in 8.15.0, before this version a long cast was necessary when passed to curl_easy_setopt.

Availability

Added in curl 7.10.8

Return value

curl_easy_setopt returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error occurred, see libcurl-errors.