A Haskell library for parsing and validating internationalized domain
names, which may contain characters from non-Latin scripts (Greek,
Hebrew, Arabic, CJK, ...) alongside the conventional letters, digits,
and hyphens.
Given a domain name as the user typed it, the library checks
that every label is well-formed, encodes any non-ASCII labels
into their ACE-prefixed form for the wire, tells the
caller what kind of label each one is, and (optionally)
renders the parsed name back to display form.
A single domain name often mixes several kinds of labels.
The library reports each label as one of: a conventional
hostname-style letter-digit-hyphen label, a legacy reserved
label, an internationalized label encoded as Punycode, an
"xn--"-prefix that turns out not to decode cleanly, a
Unicode label, an underscore-prefixed service-discovery
label (e.g. _25._tcp, _dmarc), an arbitrary-bytes label,
or the DNS wildcard. Most existing IDNA libraries don't
make these distinctions; this library does.
Strict IDNA2008. Some browsers and language standard
libraries use a more permissive variant of the IDNA standard
that accepts characters strict IDNA2008 rejects; this
library does not use that variant.
Originally factored out of the dnsbase library; conformance
test vectors are published as JSON for reuse by ports to
other languages.
