76 lines
1.7 KiB
Markdown
76 lines
1.7 KiB
Markdown
|
---
|
||
|
|
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
|
||
|
|
SPDX-License-Identifier: curl
|
||
|
|
Title: CURLOPT_DNS_SHUFFLE_ADDRESSES
|
||
|
|
Section: 3
|
||
|
|
Source: libcurl
|
||
|
|
See-also:
|
||
|
|
- CURLOPT_DNS_CACHE_TIMEOUT (3)
|
||
|
|
- CURLOPT_IPRESOLVE (3)
|
||
|
|
---
|
||
|
|
|
||
|
|
# NAME
|
||
|
|
|
||
|
|
CURLOPT_DNS_SHUFFLE_ADDRESSES - shuffle IP addresses for hostname
|
||
|
|
|
||
|
|
# SYNOPSIS
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
#include <curl/curl.h>
|
||
|
|
|
||
|
|
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff);
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# 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. CURLOPT_DNS_CACHE_TIMEOUT(3) 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.
|
||
|
|
|
||
|
|
# DEFAULT
|
||
|
|
|
||
|
|
0 (disabled)
|
||
|
|
|
||
|
|
# PROTOCOLS
|
||
|
|
|
||
|
|
All
|
||
|
|
|
||
|
|
# EXAMPLE
|
||
|
|
|
||
|
|
~~~c
|
||
|
|
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);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
~~~
|
||
|
|
|
||
|
|
# AVAILABILITY
|
||
|
|
|
||
|
|
Added in 7.60.0
|
||
|
|
|
||
|
|
# RETURN VALUE
|
||
|
|
|
||
|
|
CURLE_OK or an error such as CURLE_UNKNOWN_OPTION.
|