x/text: *Profile.process to throw labelError if verifyDNSLength = true and s ends with trailing dot.

[elliotwutingfeng]

Issue

The existing implementation of *Profile.process erroneously accepts trailing dots when verifyDNSLength is true.

This behavior is described in the Unicode Technical Standard 46 at https://unicode.org/reports/tr46/#ToASCII

Proposed change

*Profile.process to reject trailing dots when verifyDNSLength is true.

Fixes golang/go#47182

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Message from Marcel van Lohuizen:

Patch Set 1: Code-Review+1

(1 comment)

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[zeroizerz]

As per golang/go#58778 (comment):

The root label should be disallowed when VerifyDNSLength is true, so www.éxamplé.ćóḿ. should also be rejected but is currently not. So this problem does not only affect ASCII labels as believed in #47182.

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Message from Wu Tingfeng:

Patch Set 3:

(1 comment)

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