Documentation

Overview

    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 https://www.unicode.org/reports/tr46. See https://unicode.org/cldr/utility/idna.jsp for a visualization of the differences between these two standards.

    Index

    Examples

    Constants

    View Source
    const UnicodeVersion = "12.0.0"

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

      Variables

      This section is empty.

      Functions

      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.

          Types

          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.

              This option corresponds to the CheckBidi flag in UTS #46.

              func CheckHyphens

              func CheckHyphens(enable bool) Option

                CheckHyphens sets whether to check for correct use of hyphens ('-') in labels. Most web browsers do not have this option set, since labels such as "r3---sn-apo3qvuoxuxbt-j5pe" are in common use.

                This option corresponds to the CheckHyphens flag in UTS #46.

                func CheckJoiners

                func CheckJoiners(enable bool) Option

                  CheckJoiners sets whether to check the ContextJ rules as defined in Appendix A of RFC 5892, concerning the use of joiner runes.

                  This option corresponds to the CheckJoiners flag in UTS #46.

                  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.

                      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, but is only useful if ValidateLabels is set.

                        This option is useful, for instance, for browsers that allow characters outside this range, for example a '_' (U+005F LOW LINE). See http://www.rfc-editor.org/std/std3.txt for more details.

                        This option corresponds to the UseSTD3ASCIIRules flag 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. In particular, ValidateLabels also sets the CheckHyphens and CheckJoiners flags in UTS #46.

                              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.

                                This option corresponds to the VerifyDnsLength flag in UTS #46.

                                type Profile

                                type Profile struct {
                                	// contains filtered or unexported fields
                                }

                                  A Profile defines the configuration of an IDNA mapper.

                                  Example
                                  Output:
                                  
                                   <nil>
                                  *.xn--fa-hia.com <nil>
                                  *.xn--fa-hia.com <nil>
                                   <nil>
                                  www.fass.com <nil>
                                   idna: invalid label ""
                                  www.xn--fa-hia.com <nil>
                                  
                                  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.

                                    Example
                                    Output:
                                    
                                    *.xn--fa-hia.com <nil>
                                    *.fass.com idna: disallowed rune U+002A
                                    *.faß.com idna: disallowed rune U+002A
                                    *.fass.com <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("bücher.example.com") is "xn--bcher-kva.example.com", 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("xn--bcher-kva.example.com") is "bücher.example.com", and ToUnicode("golang") is "golang". If an error is encountered it will return an error and a (partially) processed result.