curl/docs/libcurl/opts/CURLOPT_DNS_SERVERS.md
Daniel Stenberg e694c8284a
docs/libcurl/opts: clarify the return values
Expand a little.

- mention the type name of the return code
- avoid stating which exact return codes that might be returned, as that
  varies over time, builds and conditions
- avoid stating some always return OK
- refer to the manpage documenting all the return codes

Closes #15900
2025-01-02 17:13:33 +01:00

80 lines
1.6 KiB
Markdown

---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_DNS_SERVERS
Section: 3
Source: libcurl
See-also:
- CURLOPT_DNS_CACHE_TIMEOUT (3)
- CURLOPT_DNS_LOCAL_IP4 (3)
- CURLOPT_DNS_LOCAL_IP6 (3)
Protocol:
- All
Added-in: 7.24.0
---
# NAME
CURLOPT_DNS_SERVERS - DNS servers to use
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_SERVERS, char *servers);
~~~
# DESCRIPTION
Pass a char pointer that is the list of DNS servers to be used instead of the
system default. The format of the dns servers option is:
host[:port][,host[:port]]...
For example:
192.168.1.100,192.168.1.101,3.4.5.6
The application does not have to keep the string around after setting this
option.
Using this option multiple times makes the last set string override the
previous ones. Set it to NULL to disable its use again.
# DEFAULT
NULL
# %PROTOCOLS%
# EXAMPLE
~~~c
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode res;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
curl_easy_setopt(curl, CURLOPT_DNS_SERVERS,
"192.168.1.100:53,192.168.1.101");
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}
~~~
# NOTES
This option requires that libcurl was built with a resolver backend that
supports this operation. The c-ares backend is the only such one.
# %AVAILABILITY%
# RETURN VALUE
curl_easy_setopt(3) returns a CURLcode indicating success or error.
CURLE_OK (0) means everything was OK, non-zero means an error occurred, see
libcurl-errors(3).