gemini-browser

idna9.0.0.go (19639B)

---

 // Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
 
 // Copyright 2016 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 //go:build !go1.10
 
 // 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.
 package idna // import "golang.org/x/net/idna"
 
 import (
 	"fmt"
 	"strings"
 	"unicode/utf8"
 
 	"golang.org/x/text/secure/bidirule"
 	"golang.org/x/text/unicode/norm"
 )
 
 // NOTE: Unlike common practice in Go APIs, the functions will return a
 // sanitized domain name in case of errors. Browsers sometimes use a partially
 // evaluated string as lookup.
 // TODO: the current error handling is, in my opinion, the least opinionated.
 // Other strategies are also viable, though:
 // Option 1) Return an empty string in case of error, but allow the user to
 //    specify explicitly which errors to ignore.
 // Option 2) Return the partially evaluated string if it is itself a valid
 //    string, otherwise return the empty string in case of error.
 // Option 3) Option 1 and 2.
 // Option 4) Always return an empty string for now and implement Option 1 as
 //    needed, and document that the return string may not be empty in case of
 //    error in the future.
 // I think Option 1 is best, but it is quite opinionated.
 
 // ToASCII is a wrapper for Punycode.ToASCII.
 func ToASCII(s string) (string, error) {
 	return Punycode.process(s, true)
 }
 
 // ToUnicode is a wrapper for Punycode.ToUnicode.
 func ToUnicode(s string) (string, error) {
 	return Punycode.process(s, false)
 }
 
 // An Option configures a Profile at creation time.
 type Option func(*options)
 
 // 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 some browsers when resolving domain names. This
 // option is only meaningful if combined with MapForLookup.
 func Transitional(transitional bool) Option {
 	return func(o *options) { o.transitional = transitional }
 }
 
 // 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.
 func VerifyDNSLength(verify bool) Option {
 	return func(o *options) { o.verifyDNSLength = verify }
 }
 
 // RemoveLeadingDots removes leading label separators. Leading runes that map to
 // dots, such as U+3002 IDEOGRAPHIC FULL STOP, are removed as well.
 func RemoveLeadingDots(remove bool) Option {
 	return func(o *options) { o.removeLeadingDots = remove }
 }
 
 // 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 ValidateLabels(enable bool) Option {
 	return func(o *options) {
 		// Don't override existing mappings, but set one that at least checks
 		// normalization if it is not set.
 		if o.mapping == nil && enable {
 			o.mapping = normalize
 		}
 		o.trie = trie
 		o.checkJoiners = enable
 		o.checkHyphens = enable
 		if enable {
 			o.fromPuny = validateFromPunycode
 		} else {
 			o.fromPuny = nil
 		}
 	}
 }
 
 // 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 CheckHyphens(enable bool) Option {
 	return func(o *options) { o.checkHyphens = enable }
 }
 
 // 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 CheckJoiners(enable bool) Option {
 	return func(o *options) {
 		o.trie = trie
 		o.checkJoiners = enable
 	}
 }
 
 // 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 StrictDomainName(use bool) Option {
 	return func(o *options) { o.useSTD3Rules = use }
 }
 
 // NOTE: the following options pull in tables. The tables should not be linked
 // in as long as the options are not used.
 
 // 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 BidiRule() Option {
 	return func(o *options) { o.bidirule = bidirule.ValidString }
 }
 
 // ValidateForRegistration sets validation options to verify that a given IDN is
 // properly formatted for registration as defined by Section 4 of RFC 5891.
 func ValidateForRegistration() Option {
 	return func(o *options) {
 		o.mapping = validateRegistration
 		StrictDomainName(true)(o)
 		ValidateLabels(true)(o)
 		VerifyDNSLength(true)(o)
 		BidiRule()(o)
 	}
 }
 
 // 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 MapForLookup() Option {
 	return func(o *options) {
 		o.mapping = validateAndMap
 		StrictDomainName(true)(o)
 		ValidateLabels(true)(o)
 		RemoveLeadingDots(true)(o)
 	}
 }
 
 type options struct {
 	transitional      bool
 	useSTD3Rules      bool
 	checkHyphens      bool
 	checkJoiners      bool
 	verifyDNSLength   bool
 	removeLeadingDots bool
 
 	trie *idnaTrie
 
 	// fromPuny calls validation rules when converting A-labels to U-labels.
 	fromPuny func(p *Profile, s string) error
 
 	// mapping implements a validation and mapping step as defined in RFC 5895
 	// or UTS 46, tailored to, for example, domain registration or lookup.
 	mapping func(p *Profile, s string) (string, error)
 
 	// bidirule, if specified, checks whether s conforms to the Bidi Rule
 	// defined in RFC 5893.
 	bidirule func(s string) bool
 }
 
 // A Profile defines the configuration of a IDNA mapper.
 type Profile struct {
 	options
 }
 
 func apply(o *options, opts []Option) {
 	for _, f := range opts {
 		f(o)
 	}
 }
 
 // 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.
 func New(o ...Option) *Profile {
 	p := &Profile{}
 	apply(&p.options, o)
 	return p
 }
 
 // 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 (p *Profile) ToASCII(s string) (string, error) {
 	return p.process(s, true)
 }
 
 // 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.
 func (p *Profile) ToUnicode(s string) (string, error) {
 	pp := *p
 	pp.transitional = false
 	return pp.process(s, false)
 }
 
 // String reports a string with a description of the profile for debugging
 // purposes. The string format may change with different versions.
 func (p *Profile) String() string {
 	s := ""
 	if p.transitional {
 		s = "Transitional"
 	} else {
 		s = "NonTransitional"
 	}
 	if p.useSTD3Rules {
 		s += ":UseSTD3Rules"
 	}
 	if p.checkHyphens {
 		s += ":CheckHyphens"
 	}
 	if p.checkJoiners {
 		s += ":CheckJoiners"
 	}
 	if p.verifyDNSLength {
 		s += ":VerifyDNSLength"
 	}
 	return s
 }
 
 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
 
 	punycode = &Profile{}
 	lookup   = &Profile{options{
 		transitional:      true,
 		removeLeadingDots: true,
 		useSTD3Rules:      true,
 		checkHyphens:      true,
 		checkJoiners:      true,
 		trie:              trie,
 		fromPuny:          validateFromPunycode,
 		mapping:           validateAndMap,
 		bidirule:          bidirule.ValidString,
 	}}
 	display = &Profile{options{
 		useSTD3Rules:      true,
 		removeLeadingDots: true,
 		checkHyphens:      true,
 		checkJoiners:      true,
 		trie:              trie,
 		fromPuny:          validateFromPunycode,
 		mapping:           validateAndMap,
 		bidirule:          bidirule.ValidString,
 	}}
 	registration = &Profile{options{
 		useSTD3Rules:    true,
 		verifyDNSLength: true,
 		checkHyphens:    true,
 		checkJoiners:    true,
 		trie:            trie,
 		fromPuny:        validateFromPunycode,
 		mapping:         validateRegistration,
 		bidirule:        bidirule.ValidString,
 	}}
 
 	// TODO: profiles
 	// Register: recommended for approving domain names: don't do any mappings
 	// but rather reject on invalid input. Bundle or block deviation characters.
 )
 
 type labelError struct{ label, code_ string }
 
 func (e labelError) code() string { return e.code_ }
 func (e labelError) Error() string {
 	return fmt.Sprintf("idna: invalid label %q", e.label)
 }
 
 type runeError rune
 
 func (e runeError) code() string { return "P1" }
 func (e runeError) Error() string {
 	return fmt.Sprintf("idna: disallowed rune %U", e)
 }
 
 // process implements the algorithm described in section 4 of UTS #46,
 // see https://www.unicode.org/reports/tr46.
 func (p *Profile) process(s string, toASCII bool) (string, error) {
 	var err error
 	if p.mapping != nil {
 		s, err = p.mapping(p, s)
 	}
 	// Remove leading empty labels.
 	if p.removeLeadingDots {
 		for ; len(s) > 0 && s[0] == '.'; s = s[1:] {
 		}
 	}
 	// It seems like we should only create this error on ToASCII, but the
 	// UTS 46 conformance tests suggests we should always check this.
 	if err == nil && p.verifyDNSLength && s == "" {
 		err = &labelError{s, "A4"}
 	}
 	labels := labelIter{orig: s}
 	for ; !labels.done(); labels.next() {
 		label := labels.label()
 		if label == "" {
 			// Empty labels are not okay. The label iterator skips the last
 			// label if it is empty.
 			if err == nil && p.verifyDNSLength {
 				err = &labelError{s, "A4"}
 			}
 			continue
 		}
 		if strings.HasPrefix(label, acePrefix) {
 			u, err2 := decode(label[len(acePrefix):])
 			if err2 != nil {
 				if err == nil {
 					err = err2
 				}
 				// Spec says keep the old label.
 				continue
 			}
 			labels.set(u)
 			if err == nil && p.fromPuny != nil {
 				err = p.fromPuny(p, u)
 			}
 			if err == nil {
 				// This should be called on NonTransitional, according to the
 				// spec, but that currently does not have any effect. Use the
 				// original profile to preserve options.
 				err = p.validateLabel(u)
 			}
 		} else if err == nil {
 			err = p.validateLabel(label)
 		}
 	}
 	if toASCII {
 		for labels.reset(); !labels.done(); labels.next() {
 			label := labels.label()
 			if !ascii(label) {
 				a, err2 := encode(acePrefix, label)
 				if err == nil {
 					err = err2
 				}
 				label = a
 				labels.set(a)
 			}
 			n := len(label)
 			if p.verifyDNSLength && err == nil && (n == 0 || n > 63) {
 				err = &labelError{label, "A4"}
 			}
 		}
 	}
 	s = labels.result()
 	if toASCII && p.verifyDNSLength && err == nil {
 		// Compute the length of the domain name minus the root label and its dot.
 		n := len(s)
 		if n > 0 && s[n-1] == '.' {
 			n--
 		}
 		if len(s) < 1 || n > 253 {
 			err = &labelError{s, "A4"}
 		}
 	}
 	return s, err
 }
 
 func normalize(p *Profile, s string) (string, error) {
 	return norm.NFC.String(s), nil
 }
 
 func validateRegistration(p *Profile, s string) (string, error) {
 	if !norm.NFC.IsNormalString(s) {
 		return s, &labelError{s, "V1"}
 	}
 	for i := 0; i < len(s); {
 		v, sz := trie.lookupString(s[i:])
 		// Copy bytes not copied so far.
 		switch p.simplify(info(v).category()) {
 		// TODO: handle the NV8 defined in the Unicode idna data set to allow
 		// for strict conformance to IDNA2008.
 		case valid, deviation:
 		case disallowed, mapped, unknown, ignored:
 			r, _ := utf8.DecodeRuneInString(s[i:])
 			return s, runeError(r)
 		}
 		i += sz
 	}
 	return s, nil
 }
 
 func validateAndMap(p *Profile, s string) (string, error) {
 	var (
 		err error
 		b   []byte
 		k   int
 	)
 	for i := 0; i < len(s); {
 		v, sz := trie.lookupString(s[i:])
 		start := i
 		i += sz
 		// Copy bytes not copied so far.
 		switch p.simplify(info(v).category()) {
 		case valid:
 			continue
 		case disallowed:
 			if err == nil {
 				r, _ := utf8.DecodeRuneInString(s[start:])
 				err = runeError(r)
 			}
 			continue
 		case mapped, deviation:
 			b = append(b, s[k:start]...)
 			b = info(v).appendMapping(b, s[start:i])
 		case ignored:
 			b = append(b, s[k:start]...)
 			// drop the rune
 		case unknown:
 			b = append(b, s[k:start]...)
 			b = append(b, "\ufffd"...)
 		}
 		k = i
 	}
 	if k == 0 {
 		// No changes so far.
 		s = norm.NFC.String(s)
 	} else {
 		b = append(b, s[k:]...)
 		if norm.NFC.QuickSpan(b) != len(b) {
 			b = norm.NFC.Bytes(b)
 		}
 		// TODO: the punycode converters require strings as input.
 		s = string(b)
 	}
 	return s, err
 }
 
 // A labelIter allows iterating over domain name labels.
 type labelIter struct {
 	orig     string
 	slice    []string
 	curStart int
 	curEnd   int
 	i        int
 }
 
 func (l *labelIter) reset() {
 	l.curStart = 0
 	l.curEnd = 0
 	l.i = 0
 }
 
 func (l *labelIter) done() bool {
 	return l.curStart >= len(l.orig)
 }
 
 func (l *labelIter) result() string {
 	if l.slice != nil {
 		return strings.Join(l.slice, ".")
 	}
 	return l.orig
 }
 
 func (l *labelIter) label() string {
 	if l.slice != nil {
 		return l.slice[l.i]
 	}
 	p := strings.IndexByte(l.orig[l.curStart:], '.')
 	l.curEnd = l.curStart + p
 	if p == -1 {
 		l.curEnd = len(l.orig)
 	}
 	return l.orig[l.curStart:l.curEnd]
 }
 
 // next sets the value to the next label. It skips the last label if it is empty.
 func (l *labelIter) next() {
 	l.i++
 	if l.slice != nil {
 		if l.i >= len(l.slice) || l.i == len(l.slice)-1 && l.slice[l.i] == "" {
 			l.curStart = len(l.orig)
 		}
 	} else {
 		l.curStart = l.curEnd + 1
 		if l.curStart == len(l.orig)-1 && l.orig[l.curStart] == '.' {
 			l.curStart = len(l.orig)
 		}
 	}
 }
 
 func (l *labelIter) set(s string) {
 	if l.slice == nil {
 		l.slice = strings.Split(l.orig, ".")
 	}
 	l.slice[l.i] = s
 }
 
 // acePrefix is the ASCII Compatible Encoding prefix.
 const acePrefix = "xn--"
 
 func (p *Profile) simplify(cat category) category {
 	switch cat {
 	case disallowedSTD3Mapped:
 		if p.useSTD3Rules {
 			cat = disallowed
 		} else {
 			cat = mapped
 		}
 	case disallowedSTD3Valid:
 		if p.useSTD3Rules {
 			cat = disallowed
 		} else {
 			cat = valid
 		}
 	case deviation:
 		if !p.transitional {
 			cat = valid
 		}
 	case validNV8, validXV8:
 		// TODO: handle V2008
 		cat = valid
 	}
 	return cat
 }
 
 func validateFromPunycode(p *Profile, s string) error {
 	if !norm.NFC.IsNormalString(s) {
 		return &labelError{s, "V1"}
 	}
 	for i := 0; i < len(s); {
 		v, sz := trie.lookupString(s[i:])
 		if c := p.simplify(info(v).category()); c != valid && c != deviation {
 			return &labelError{s, "V6"}
 		}
 		i += sz
 	}
 	return nil
 }
 
 const (
 	zwnj = "\u200c"
 	zwj  = "\u200d"
 )
 
 type joinState int8
 
 const (
 	stateStart joinState = iota
 	stateVirama
 	stateBefore
 	stateBeforeVirama
 	stateAfter
 	stateFAIL
 )
 
 var joinStates = [][numJoinTypes]joinState{
 	stateStart: {
 		joiningL:   stateBefore,
 		joiningD:   stateBefore,
 		joinZWNJ:   stateFAIL,
 		joinZWJ:    stateFAIL,
 		joinVirama: stateVirama,
 	},
 	stateVirama: {
 		joiningL: stateBefore,
 		joiningD: stateBefore,
 	},
 	stateBefore: {
 		joiningL:   stateBefore,
 		joiningD:   stateBefore,
 		joiningT:   stateBefore,
 		joinZWNJ:   stateAfter,
 		joinZWJ:    stateFAIL,
 		joinVirama: stateBeforeVirama,
 	},
 	stateBeforeVirama: {
 		joiningL: stateBefore,
 		joiningD: stateBefore,
 		joiningT: stateBefore,
 	},
 	stateAfter: {
 		joiningL:   stateFAIL,
 		joiningD:   stateBefore,
 		joiningT:   stateAfter,
 		joiningR:   stateStart,
 		joinZWNJ:   stateFAIL,
 		joinZWJ:    stateFAIL,
 		joinVirama: stateAfter, // no-op as we can't accept joiners here
 	},
 	stateFAIL: {
 		0:          stateFAIL,
 		joiningL:   stateFAIL,
 		joiningD:   stateFAIL,
 		joiningT:   stateFAIL,
 		joiningR:   stateFAIL,
 		joinZWNJ:   stateFAIL,
 		joinZWJ:    stateFAIL,
 		joinVirama: stateFAIL,
 	},
 }
 
 // validateLabel validates the criteria from Section 4.1. Item 1, 4, and 6 are
 // already implicitly satisfied by the overall implementation.
 func (p *Profile) validateLabel(s string) error {
 	if s == "" {
 		if p.verifyDNSLength {
 			return &labelError{s, "A4"}
 		}
 		return nil
 	}
 	if p.bidirule != nil && !p.bidirule(s) {
 		return &labelError{s, "B"}
 	}
 	if p.checkHyphens {
 		if len(s) > 4 && s[2] == '-' && s[3] == '-' {
 			return &labelError{s, "V2"}
 		}
 		if s[0] == '-' || s[len(s)-1] == '-' {
 			return &labelError{s, "V3"}
 		}
 	}
 	if !p.checkJoiners {
 		return nil
 	}
 	trie := p.trie // p.checkJoiners is only set if trie is set.
 	// TODO: merge the use of this in the trie.
 	v, sz := trie.lookupString(s)
 	x := info(v)
 	if x.isModifier() {
 		return &labelError{s, "V5"}
 	}
 	// Quickly return in the absence of zero-width (non) joiners.
 	if strings.Index(s, zwj) == -1 && strings.Index(s, zwnj) == -1 {
 		return nil
 	}
 	st := stateStart
 	for i := 0; ; {
 		jt := x.joinType()
 		if s[i:i+sz] == zwj {
 			jt = joinZWJ
 		} else if s[i:i+sz] == zwnj {
 			jt = joinZWNJ
 		}
 		st = joinStates[st][jt]
 		if x.isViramaModifier() {
 			st = joinStates[st][joinVirama]
 		}
 		if i += sz; i == len(s) {
 			break
 		}
 		v, sz = trie.lookupString(s[i:])
 		x = info(v)
 	}
 	if st == stateFAIL || st == stateAfter {
 		return &labelError{s, "C"}
 	}
 	return nil
 }
 
 func ascii(s string) bool {
 	for i := 0; i < len(s); i++ {
 		if s[i] >= utf8.RuneSelf {
 			return false
 		}
 	}
 	return true
 }