Package idna implements IDNA2008 using the compatibility processing defined by UTS (Unicode Technical Standard) #46, which defines a standard to deal with the transition from IDNA2003.

    IDNA2008 (Internationalized Domain Names for Applications), is defined in RFC 5890, RFC 5891, RFC 5892, RFC 5893 and RFC 5894. UTS #46 is defined in See for a visualization of the differences between these two standards.




    View Source
    const UnicodeVersion = "13.0.0"

      UnicodeVersion is the Unicode version from which the tables in this package are derived.


      This section is empty.


      func ToASCII

      func ToASCII(s string) (string, error)

        ToASCII is a wrapper for Punycode.ToASCII.

        func ToUnicode

        func ToUnicode(s string) (string, error)

          ToUnicode is a wrapper for Punycode.ToUnicode.


          type Option

          type Option func(*options)

            An Option configures a Profile at creation time.

            func BidiRule

            func BidiRule() Option

              BidiRule enables the Bidi rule as defined in RFC 5893. Any application that relies on proper validation of labels should include this rule.

              func MapForLookup

              func MapForLookup() Option

                MapForLookup sets validation and mapping options such that a given IDN is transformed for domain name lookup according to the requirements set out in Section 5 of RFC 5891. The mappings follow the recommendations of RFC 5894, RFC 5895 and UTS 46. It does not add the Bidi Rule. Use the BidiRule option to add this check.

                The mappings include normalization and mapping case, width and other compatibility mappings.

                func RemoveLeadingDots

                func RemoveLeadingDots(remove bool) Option

                  RemoveLeadingDots removes leading label separators. Leading runes that map to dots, such as U+3002 IDEOGRAPHIC FULL STOP, are removed as well.

                  This is the behavior suggested by the UTS #46 and is adopted by some browsers.

                  func StrictDomainName

                  func StrictDomainName(use bool) Option

                    StrictDomainName limits the set of permissible ASCII characters to those allowed in domain names as defined in RFC 1034 (A-Z, a-z, 0-9 and the hyphen). This is set by default for MapForLookup and ValidateForRegistration.

                    This option is useful, for instance, for browsers that allow characters outside this range, for example a '_' (U+005F LOW LINE). See for more details This option corresponds to the UseSTD3ASCIIRules option in UTS #46.

                    func Transitional

                    func Transitional(transitional bool) Option

                      Transitional sets a Profile to use the Transitional mapping as defined in UTS #46. This will cause, for example, "ß" to be mapped to "ss". Using the transitional mapping provides a compromise between IDNA2003 and IDNA2008 compatibility. It is used by most browsers when resolving domain names. This option is only meaningful if combined with MapForLookup.

                      func ValidateForRegistration

                      func ValidateForRegistration() Option

                        ValidateForRegistration sets validation options to verify that a given IDN is properly formatted for registration as defined by Section 4 of RFC 5891.

                        func ValidateLabels

                        func ValidateLabels(enable bool) Option

                          ValidateLabels sets whether to check the mandatory label validation criteria as defined in Section 5.4 of RFC 5891. This includes testing for correct use of hyphens ('-'), normalization, validity of runes, and the context rules.

                          func VerifyDNSLength

                          func VerifyDNSLength(verify bool) Option

                            VerifyDNSLength sets whether a Profile should fail if any of the IDN parts are longer than allowed by the RFC.

                            type Profile

                            type Profile struct {
                            	// contains filtered or unexported fields

                              A Profile defines the configuration of an IDNA mapper.

                              * <nil>
                              * <nil>
                               idna: invalid label ""
                              var (
                              	// Punycode is a Profile that does raw punycode processing with a minimum
                              	// of validation.
                              	Punycode *Profile = punycode
                              	// Lookup is the recommended profile for looking up domain names, according
                              	// to Section 5 of RFC 5891. The exact configuration of this profile may
                              	// change over time.
                              	Lookup *Profile = lookup
                              	// Display is the recommended profile for displaying domain names.
                              	// The configuration of this profile may change over time.
                              	Display *Profile = display
                              	// Registration is the recommended profile for checking whether a given
                              	// IDN is valid for registration, according to Section 4 of RFC 5891.
                              	Registration *Profile = registration

                              func New

                              func New(o ...Option) *Profile

                                New creates a new Profile.

                                With no options, the returned Profile is the most permissive and equals the Punycode Profile. Options can be passed to further restrict the Profile. The MapForLookup and ValidateForRegistration options set a collection of options, for lookup and registration purposes respectively, which can be tailored by adding more fine-grained options, where later options override earlier options.

                                * <nil>
                                * idna: disallowed rune U+002A
                                *.faß.com idna: disallowed rune U+002A
                                * <nil>

                                func (*Profile) String

                                func (p *Profile) String() string

                                  String reports a string with a description of the profile for debugging purposes. The string format may change with different versions.

                                  func (*Profile) ToASCII

                                  func (p *Profile) ToASCII(s string) (string, error)

                                    ToASCII converts a domain or domain label to its ASCII form. For example, ToASCII("bü") is "", and ToASCII("golang") is "golang". If an error is encountered it will return an error and a (partially) processed result.

                                    func (*Profile) ToUnicode

                                    func (p *Profile) ToUnicode(s string) (string, error)

                                      ToUnicode converts a domain or domain label to its Unicode form. For example, ToUnicode("") is "bü", and ToUnicode("golang") is "golang". If an error is encountered it will return an error and a (partially) processed result.