[Bug 1771109] Re: Domain names containing emoji characters are not supported in console applications

[augeus]

Attached is a patch enabling resolution of emoji domain names on
programs that use libidn2. It patches the script get-tables-from-iana.pl
to set the state of emoji characters to PVALID, and uses the
experimental perl "smartmatch" operator, which may make it unacceptable.
Nevertheless, I believe that it provides a proof that a solution is
possible, and might prove useful to people having to resolve such
domains from a console application, so I am posting it here. It is
provided with ABSOLUTELY NO WARRANTY. However, this patch does not
affect applications using glibc to resolve domains. As such, I am
tagging this as an issue in glibc, too.

Of course, I understand that IANA disallows the use of emojis in domain
names. Perhaps a solution could be to resolve these domains, but print a
warning on the user's console? I do not have time to think about this.

** Patch added: "gen-tables-from-iana.patch"
   https://bugs.launchpad.net/ubuntu/+source/libidn2-0/+bug/1771109/+attachment/5139707/+files/gen-tables-from-iana.patch

** Also affects: glibc (Ubuntu)
   Importance: Undecided
       Status: New

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https://bugs.launchpad.net/bugs/1771109

Title:
  Domain names containing emoji characters are not supported in console
  applications

Status in glibc package in Ubuntu:
  New
Status in libidn2-0 package in Ubuntu:
  New

Bug description:
  Ubuntu release:
  user at machine:~$ lsb_release -rd
  Description:	Ubuntu 18.04 LTS
  Release:	18.04

  Description:
  What I did: Attempted to access a domain name containing an emoji character using curl and other terminal applications
  What I expected to happen: Successfully interact with the server represented by said domain name
  What happened instead: Got error saying that the domain contains a disallowed character.
  Notes: Accessing such a domain using firefox works normally. Interacting with the domain using its punycode form works just fine. Accessing IDNs containing national characters (such as hxxp://ąćęłńóśźż.pl/) works as intended.

  Steps to reproduce:
  user at machine:~$ curl 📙.la
  curl: (3) Failed to convert 📙.la to ACE; string contains a disallowed character

  Disclosure: I own such a domain name, but it is not the domain
  provided in the example.

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