c-ares 为 DNS 解析指定网络接口

c-ares specifying network interface for the DNS resolves(c-ares 为 DNS 解析指定网络接口)

问题描述

有没有办法设置DNS请求可以绑定到的网络接口.

Is there a way in which you can set the network interface to which the DNS requests can be bound to.

我们有一个项目需要使用高优先级流会话通过一个接口，所有其他请求通过第二个接口.

We have a project which requires to use a highpriority streaming session go through one interface and all the other requests channeled through the second one.

示例:设置 'eth0' 以便所有 ares 请求都通过 'eth0' 而不是在 'wlan0' 上.

example: setting 'eth0' so that all the ares requests will go through 'eth0' and not on 'wlan0'.

我在 c-ares(在 ares_init_options() API 中)找不到任何提供此设置界面选项的 API.

I was not able to find any API in c-ares (in ares_init_options() API) that gives this option of setting interface.

如果有什么方法可以做到这一点，或者我错过了什么，请告诉我.

Can you please let me know if there is some way to achive this or if I missed something.

谢谢，阿俊

推荐答案

如果你有一个相当新的 c-ares (c-ares >= 1.7.4)，请查看 ares.h(这是我唯一的地方实际上发现它被引用了).

If you have a fairly new c-ares (c-ares >= 1.7.4), check out ares.h (It's the only place I've actually found it referenced).

/* These next 3 configure local binding for the out-going socket
 * connection.  Use these to specify source IP and/or network device
 * on multi-homed systems.
 */
CARES_EXTERN void ares_set_local_ip4(ares_channel channel, unsigned int local_ip);

/* local_ip6 should be 16 bytes in length */
CARES_EXTERN void ares_set_local_ip6(ares_channel channel,
                                     const unsigned char* local_ip6);

/* local_dev_name should be null terminated. */
CARES_EXTERN void ares_set_local_dev(ares_channel channel,
                                     const char* local_dev_name);

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