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| .\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. |
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| .TH CURLOPT_DNS_SHUFFLE_ADDRESSES 3 "3 March 2018" libcurl libcurl |
| .SH NAME |
| CURLOPT_DNS_SHUFFLE_ADDRESSES \- shuffle IP addresses for hostname |
| .SH SYNOPSIS |
| .nf |
| #include <curl/curl.h> |
| |
| CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff); |
| .fi |
| .SH DESCRIPTION |
| Pass a long set to 1 to enable this option. |
| |
| When a name is resolved and more than one IP address is returned, this |
| function shuffles the order of all returned addresses so that they are used in |
| a random order. This is similar to the ordering behavior of the legacy |
| gethostbyname function which is no longer used on most platforms. |
| |
| Addresses are not reshuffled if name resolution is completed using the DNS |
| cache. \fICURLOPT_DNS_CACHE_TIMEOUT(3)\fP can be used together with this |
| option to reduce DNS cache timeout or disable caching entirely if frequent |
| reshuffling is needed. |
| |
| Since the addresses returned are randomly reordered, the order is not in |
| accordance with RFC 3484 or any other deterministic order that may be |
| generated by the system's name resolution implementation. This may have |
| performance impacts and may cause IPv4 to be used before IPv6 or vice versa. |
| .SH DEFAULT |
| 0 (disabled) |
| .SH PROTOCOLS |
| All |
| .SH EXAMPLE |
| .nf |
| int main(void) |
| { |
| CURL *curl = curl_easy_init(); |
| if(curl) { |
| curl_easy_setopt(curl, CURLOPT_URL, "https://example.com"); |
| curl_easy_setopt(curl, CURLOPT_DNS_SHUFFLE_ADDRESSES, 1L); |
| |
| curl_easy_perform(curl); |
| |
| /* always cleanup */ |
| curl_easy_cleanup(curl); |
| } |
| } |
| .fi |
| .SH AVAILABILITY |
| Added in 7.60.0 |
| .SH RETURN VALUE |
| CURLE_OK or an error such as CURLE_UNKNOWN_OPTION. |
| .SH "SEE ALSO" |
| .BR CURLOPT_DNS_CACHE_TIMEOUT (3), |
| .BR CURLOPT_IPRESOLVE (3) |
