There's no "I" in IDN part 8: Punycode don't do the PUA

by Michael S. Kaplan, published on 2011/08/12 07:01 -04:00, original URI: http://blogs.msdn.com/b/michkap/archive/2011/08/12/10195062.aspx


Previous parts in this series:

The other day an interesting issue came up while a team worked to provide IDN support:

Picking an Uri item fails when the input data is something like "http://www.覞嬁ﺞ쫽礗萦笧䶉럼.com".

Note: the domain name portion is a randomly generated string and it doesn't have to be exactly above. It is repro with another randomly generated string also.

Also note that if the above string is shortened to "http://www.覞嬁ﺞ쫽礗萦.com", the action works.

In a way, the answer is in the question!

On the road to Punycode, there are two different processes going on:

And characters in the PUA (PRIVATE USE AREA) like , aka U+e216, have no public, agreed upon context.

Thus, they have no place in Punycode. Or in IDN.

This is different but somewhat akin to the behavior of IsNLSDefinedString that I described in Keeping out the undesirables? a few years back...


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referenced by

2013/10/17 There's no "I" in IDN, part 19: There's no "I" in IPv6, either!

2013/10/08 There's no "I" in IDN, part 18: There isn't even an "I" in John C. Klensin's name!

2013/09/13 There's no "I" in IDN, part 17: EAI made it to China, and everybody knows it!

2013/04/19 There's no "I" in IDN, part 16: It's a good thing they decided to call it EAI!

2012/10/12 There's no "I" in IDN, part 15: Still no 'I' in EAI.... but we could use an US sometime soon!

2012/08/08 There's no "I" in IDN, part 14: It turns out there's no "I" in IE, either

2012/05/18 There's no "I" in IDN, part 13: Desktop and Managed and Metro; oh my!

2012/02/27 There's no "I" in IDN, part 12: Emoji + IDN == U+1F4A9 (PILE OF POO)

2011/10/25 There's no "I" in IDN, part 11: There's no place like ::1, not even 127.0.0.1!

2011/09/21 There's no "I" in IDN, part 10: Who needs IDN support? How much? When? (Part 2)

2011/09/16 There's no "I" in IDN, part 9: Who needs IDN support? How much? When? (Part 1)

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