[spec] C program to resolve UTF-8 IDNs

[Scot]

On 3/17/21 9:13 PM, Sean Conner wrote:
> It was thus said that the Great Scot once stated:
>> Hi Sean,
>    Hi Scot!
>
>> I think you were wondering whether it's possible to resolve UTF-8
>> IDNs with a C or Lua program. This Linux C program [7] will do so
>> via glibc's getaddrinfo(). For platforms without glibc such as the
>> BSDs, ports of the libidn library [1] are available.
>>
>> ...
>>
>> Thoughts?
>    Thank you *so* much for the sample code, and providing much needed
> background information about this.  This will make the final decision on IRI
> support a bit easier to make.  I was not aware of the GNU-specific AI_IDN
> flag to getaddrinfo() (and I wish it was standard actually), and yes, it
> does work on systems that have it (Linux).
>
>    Just one thing though---you might want to be careful when pasting code
> into email---the code below contained non-breaking spaces that my C compiler
> (gcc) did not like.  It's an easy fix, so this is mostly an FYI getting
> weird errors when compiling the code below.
>
>    Again, thank you for your message.
I appreciate the work you are doing and am glad that this might
have helped.

And thanks for posting the corrected code. I think it's missing the
first line, which is necessary on my system:
#define _GNU_SOURCE

>    -spc
>
>> [1] https://www.gnu.org/software/libidn/
>> [2] https://docs.microsoft.com/en-us/windows/win32/api/winnls/nf-winnls-idntoascii
>> [3] https://docs.microsoft.com/en-us/windows/win32/api/ws2tcpip/nf-ws2tcpip-getaddrinfo
>> [4] https://devstreaming-cdn.apple.com/videos/wwdc/2016/714urluxe140lardrb7/714/714_networking_for_the_modern_internet.pdf?dl=1
>> [5] https://developer.android.com/reference/kotlin/java/net/IDN
>> [6] https://developer.android.com/reference/android/icu/text/IDNA
>> [7] Public domain example C program to resolve UTF-8 IDNs
> P.S.  Here's the code with the non-breaking spaces removed.
>
> #include <locale.h>
> #include <netdb.h>
> #include <stdio.h>
> #include <string.h>
> ...
>