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authorRick Deist <dreckard@users.noreply.github.com>2018-03-17 20:10:04 +0100
committerDaniel Stenberg <daniel@haxx.se>2018-03-17 20:44:14 +0100
commitd95f3dc0b117b0677700dae8dd51145c9b6f2d08 (patch)
treef1f044908f412bc3a946f61fa611884c0ff1611b /docs/libcurl
parentfb4f568b1e090c884eb63c3419322b558a38138e (diff)
resolve: add CURLOPT_DNS_SHUFFLE_ADDRESSES
This patch adds CURLOPT_DNS_SHUFFLE_ADDRESSES to explicitly request shuffling of IP addresses returned for a hostname when there is more than one. This is useful when the application knows that a round robin approach is appropriate and is willing to accept the consequences of potentially discarding some preference order returned by the system's implementation. Closes #1694
Diffstat (limited to 'docs/libcurl')
-rw-r--r--docs/libcurl/curl_easy_setopt.32
-rw-r--r--docs/libcurl/opts/CURLOPT_DNS_SHUFFLE_ADDRESSES.369
-rw-r--r--docs/libcurl/opts/Makefile.inc1
-rw-r--r--docs/libcurl/symbols-in-versions1
4 files changed, 73 insertions, 0 deletions
diff --git a/docs/libcurl/curl_easy_setopt.3 b/docs/libcurl/curl_easy_setopt.3
index b7d67f360..97883d85d 100644
--- a/docs/libcurl/curl_easy_setopt.3
+++ b/docs/libcurl/curl_easy_setopt.3
@@ -468,6 +468,8 @@ Bind name resolves to this IP4 address. See \fICURLOPT_DNS_LOCAL_IP4(3)\fP
Bind name resolves to this IP6 address. See \fICURLOPT_DNS_LOCAL_IP6(3)\fP
.IP CURLOPT_DNS_SERVERS
Preferred DNS servers. See \fICURLOPT_DNS_SERVERS(3)\fP
+.IP CURLOPT_DNS_SHUFFLE_ADDRESSES
+Shuffle addresses before use. See \fICURLOPT_DNS_SHUFFLE_ADDRESSES(3)\fP
.IP CURLOPT_ACCEPTTIMEOUT_MS
Timeout for waiting for the server's connect back to be accepted. See \fICURLOPT_ACCEPTTIMEOUT_MS(3)\fP
.IP CURLOPT_HAPPY_EYEBALLS_TIMEOUT_MS
diff --git a/docs/libcurl/opts/CURLOPT_DNS_SHUFFLE_ADDRESSES.3 b/docs/libcurl/opts/CURLOPT_DNS_SHUFFLE_ADDRESSES.3
new file mode 100644
index 000000000..8af2d0aa2
--- /dev/null
+++ b/docs/libcurl/opts/CURLOPT_DNS_SHUFFLE_ADDRESSES.3
@@ -0,0 +1,69 @@
+.\" **************************************************************************
+.\" * _ _ ____ _
+.\" * Project ___| | | | _ \| |
+.\" * / __| | | | |_) | |
+.\" * | (__| |_| | _ <| |___
+.\" * \___|\___/|_| \_\_____|
+.\" *
+.\" * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" *
+.\" * This software is licensed as described in the file COPYING, which
+.\" * you should have received as part of this distribution. The terms
+.\" * are also available at https://curl.haxx.se/docs/copyright.html.
+.\" *
+.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+.\" * copies of the Software, and permit persons to whom the Software is
+.\" * furnished to do so, under the terms of the COPYING file.
+.\" *
+.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+.\" * KIND, either express or implied.
+.\" *
+.\" **************************************************************************
+.\"
+.TH CURLOPT_DNS_SHUFFLE_ADDRESSES 3 "3 March 2018" "libcurl 7.60.0" "curl_easy_setopt options"
+.SH NAME
+CURLOPT_DNS_SHUFFLE_ADDRESSES \- Shuffle addresses when a hostname returns more than one
+.SH SYNOPSIS
+.nf
+#include <curl/curl.h>
+
+CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SHUFFLE_ADDRESSES, long onoff);
+.fi
+.SH DESCRIPTION
+When a name is resolved and more than one IP address is returned, shuffle the
+order of all returned addresses so that they will be used in a random order.
+This is similar to the ordering behavior of gethostbyname which is no longer
+used on most platforms.
+
+Addresses will not be reshuffled if a 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 will be reordered randomly, their order will not
+be 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
+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), " CURLOPT_IPRESOLVE "(3), "
diff --git a/docs/libcurl/opts/Makefile.inc b/docs/libcurl/opts/Makefile.inc
index b370082d6..80488bfa3 100644
--- a/docs/libcurl/opts/Makefile.inc
+++ b/docs/libcurl/opts/Makefile.inc
@@ -112,6 +112,7 @@ man_MANS = \
CURLOPT_DNS_LOCAL_IP4.3 \
CURLOPT_DNS_LOCAL_IP6.3 \
CURLOPT_DNS_SERVERS.3 \
+ CURLOPT_DNS_SHUFFLE_ADDRESSES.3 \
CURLOPT_DNS_USE_GLOBAL_CACHE.3 \
CURLOPT_EGDSOCKET.3 \
CURLOPT_ERRORBUFFER.3 \
diff --git a/docs/libcurl/symbols-in-versions b/docs/libcurl/symbols-in-versions
index 2877de7f1..52e8407dd 100644
--- a/docs/libcurl/symbols-in-versions
+++ b/docs/libcurl/symbols-in-versions
@@ -373,6 +373,7 @@ CURLOPT_DNS_INTERFACE 7.33.0
CURLOPT_DNS_LOCAL_IP4 7.33.0
CURLOPT_DNS_LOCAL_IP6 7.33.0
CURLOPT_DNS_SERVERS 7.24.0
+CURLOPT_DNS_SHUFFLE_ADDRESSES 7.60.0
CURLOPT_DNS_USE_GLOBAL_CACHE 7.9.3 7.11.1
CURLOPT_EGDSOCKET 7.7
CURLOPT_ENCODING 7.10