1---
2c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_DNS_INTERFACE
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_DNS_LOCAL_IP4 (3)
9  - CURLOPT_DNS_LOCAL_IP6 (3)
10  - CURLOPT_DNS_SERVERS (3)
11  - CURLOPT_INTERFACE (3)
12Protocol:
13  - All
14Added-in: 7.33.0
15---
16
17# NAME
18
19CURLOPT_DNS_INTERFACE - interface to speak DNS over
20
21# SYNOPSIS
22
23~~~c
24#include <curl/curl.h>
25
26CURLcode curl_easy_setopt(CURL *handle, CURLOPT_DNS_INTERFACE, char *ifname);
27~~~
28
29# DESCRIPTION
30
31Pass a char pointer as parameter. Set the name of the network interface that
32the DNS resolver should bind to. This must be an interface name (not an
33address). Set this option to NULL to use the default setting (do not bind to a
34specific interface).
35
36The application does not have to keep the string around after setting this
37option.
38
39Using this option multiple times makes the last set string override the
40previous ones. Set it to NULL to disable its use again.
41
42# DEFAULT
43
44NULL
45
46# %PROTOCOLS%
47
48# EXAMPLE
49
50~~~c
51int main(void)
52{
53  CURL *curl = curl_easy_init();
54  if(curl) {
55    CURLcode res;
56    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/foo.bin");
57    curl_easy_setopt(curl, CURLOPT_DNS_INTERFACE, "eth0");
58    res = curl_easy_perform(curl);
59    curl_easy_cleanup(curl);
60  }
61}
62~~~
63
64# NOTES
65
66This option requires that libcurl was built with a resolver backend that
67supports this operation. The c-ares backend is the only such one.
68
69# %AVAILABILITY%
70
71# RETURN VALUE
72
73Returns CURLE_OK if the option is supported, CURLE_UNKNOWN_OPTION if not,
74or CURLE_NOT_BUILT_IN if support was disabled at compile-time.
75