Tests if hostname contains segments with an ASCII-compatible encoding of an Internationalized Domain Name. If this returns TRUE, you should decode the hostname with g_hostname_to_unicode() before displaying it to the user. Note that a hostname might contain a mix of encoded and unencoded segments, and so it is possible for g_hostname_is_non_ascii() and g_hostname_is_ascii_encoded() to both return TRUE for a name. Since 2.22
Tests if hostname is the string form of an IPv4 or IPv6 address. (Eg, "192.168.0.1".) Since 2.22
Tests if hostname contains Unicode characters. If this returns TRUE, you need to encode the hostname with g_hostname_to_ascii() before using it in non-IDN-aware contexts. Note that a hostname might contain a mix of encoded and unencoded segments, and so it is possible for g_hostname_is_non_ascii() and g_hostname_is_ascii_encoded() to both return TRUE for a name. Since 2.22
Converts hostname to its canonical ASCII form; an ASCII-only string containing no uppercase letters and not ending with a trailing dot. Since 2.22
Converts hostname to its canonical presentation form; a UTF-8 string in Unicode normalization form C, containing no uppercase letters, no forbidden characters, and no ASCII-encoded segments, and not ending with a trailing dot. Of course if hostname is not an internationalized hostname, then the canonical presentation form will be entirely ASCII. Since 2.22
Functions for manipulating internet hostnames; in particular, for converting between Unicode and ASCII-encoded forms of Internationalized Domain Names (IDNs).
The Internationalized Domain Names for Applications (IDNA) standards allow for the use of Unicode domain names in applications, while providing backward-compatibility with the old ASCII-only DNS, by defining an ASCII-Compatible Encoding of any given Unicode name, which can be used with non-IDN-aware applications and protocols. (For example, "Παν語.org" maps to "xn--4wa8awb4637h.org".)