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