punycode: Encode, Decode and Validate International Domain Names

In hrbrmstr/punycode: Encode, Decode and Validate International Domain Names

Description

Punycode uses the GNU libidn http://www.gnu.org/software/libidn/ library and provides functions to encode, decode & validate Punycode and Internationalizing Domain Names in Applications (IDNA) domains.

Details

Punycode is a simple and efficient transfer encoding syntax designed for use with Internationalized Domain Names in Applications. It uniquely and reversibly transforms a Unicode string into an ASCII string. ASCII characters in the Unicode string are represented literally, and non-ASCII characters are represented by ASCII characters that are allowed in host name labels (letters, digits, and hyphens).

Until now, there has been no standard method for domain names to use characters outside the ASCII repertoire. The IDNA document defines internationalized domain names (IDNs) and a mechanism called IDNA for handling them in a standard fashion. IDNs use characters drawn from a large repertoire (Unicode), but IDNA allows the non-ASCII characters to be represented using only the ASCII characters already allowed in so-called host names today. This backward-compatible representation is required in existing protocols like DNS, so that IDNs can be introduced with no changes to the existing infrastructure. IDNA is only meant for processing domain names, not free text.

Organizations that manage some Top Level Domains (TLDs) have published tables with characters they accept within the domain. The reason may be to reduce complexity that come from using the full Unicode range, and to protect themselves from future (backwards incompatible) changes in the IDN or Unicode specifications. Libidn (and, hence, this package) implements an infrastructure for defining and checking strings against such tables.

Author(s)

Bob Rudis (@hrbrmstr)

hrbrmstr/punycode documentation built on May 17, 2019, 5:12 p.m.