how can I get the original dns information on iOS.

Question

Created Jan ’18

Replies 5

Boosts 0

Participants 2

Hello,

I am developing a Network Extension on iOS, I have a problem. After my VPN started, I want to know whether the original dns changed. I know that the functions in <resolv.h> can get the current dns information, but it seems these functions are based on file resolv.conf, after the VPN established, the dns will be replaced by the VPN settings, so I can not get the original dns settings any more. Is there a workaround to get the information.

Then

Thanks!

Boost

Answer 1

DTS Engineer OP

Apple

Jan ’18

I know that the functions incan get the current dns information …

That’s not true, alas. There is no API that will get you a full view of the device’s DNS setup. The legacy

<resolv.h>

API doesn’t suffice because it can only return a single list of DNS servers, and iOS’s is much more complex than that.

What you’re high-level goal here? What do you need the original DNS configuration for?

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

0

Answer 2

gazeboxu OP

Jan ’18

Hello eskimo,

Thanks for your quick reply. I am trying to implement a dns proxy on iOS(you can think add some policy on dns resolving), I need the original dns information to do the real DNS resolving, and for some reason, I can not use the high level functions such as gethostbyname or getaddinfo. Are there workaround?

thanks.

0

Answer 3

DTS Engineer OP

Apple

Jan ’18

Have you looked at

NEDNSProxyProvider

? That’s the recommended way forward here, and it does give you access to the system’s basic DNS configuration (via the

systemDNSSettings

property).

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

0

Answer 4

gazeboxu OP

Jan ’18

it seems NEDNSProxyProvider can only be used on managed devices, right?

0

Answer 5

DTS Engineer OP

Apple

Jan ’18

it seems NEDNSProxyProvider can only be used on managed devices, right?

Actually, it’s worse than that )-: Currently

NEDNSProxyProvider

is only available on supervised devices. I’m hoping that we will lift that restriction (r. 34843801) but, alas, I can’t predict when it’ll happen.

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

0