summaryrefslogtreecommitdiff
path: root/vendor/golang.org/x/text/secure/precis/profile.go
diff options
context:
space:
mode:
Diffstat (limited to 'vendor/golang.org/x/text/secure/precis/profile.go')
-rw-r--r--vendor/golang.org/x/text/secure/precis/profile.go402
1 files changed, 402 insertions, 0 deletions
diff --git a/vendor/golang.org/x/text/secure/precis/profile.go b/vendor/golang.org/x/text/secure/precis/profile.go
new file mode 100644
index 0000000..0419159
--- /dev/null
+++ b/vendor/golang.org/x/text/secure/precis/profile.go
@@ -0,0 +1,402 @@
+// Copyright 2015 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.
+
+package precis
+
+import (
+ "bytes"
+ "errors"
+ "unicode/utf8"
+
+ "golang.org/x/text/cases"
+ "golang.org/x/text/language"
+ "golang.org/x/text/runes"
+ "golang.org/x/text/secure/bidirule"
+ "golang.org/x/text/transform"
+ "golang.org/x/text/width"
+)
+
+var (
+ errDisallowedRune = errors.New("precis: disallowed rune encountered")
+)
+
+var dpTrie = newDerivedPropertiesTrie(0)
+
+// A Profile represents a set of rules for normalizing and validating strings in
+// the PRECIS framework.
+type Profile struct {
+ options
+ class *class
+}
+
+// NewIdentifier creates a new PRECIS profile based on the Identifier string
+// class. Profiles created from this class are suitable for use where safety is
+// prioritized over expressiveness like network identifiers, user accounts, chat
+// rooms, and file names.
+func NewIdentifier(opts ...Option) *Profile {
+ return &Profile{
+ options: getOpts(opts...),
+ class: identifier,
+ }
+}
+
+// NewFreeform creates a new PRECIS profile based on the Freeform string class.
+// Profiles created from this class are suitable for use where expressiveness is
+// prioritized over safety like passwords, and display-elements such as
+// nicknames in a chat room.
+func NewFreeform(opts ...Option) *Profile {
+ return &Profile{
+ options: getOpts(opts...),
+ class: freeform,
+ }
+}
+
+// NewTransformer creates a new transform.Transformer that performs the PRECIS
+// preparation and enforcement steps on the given UTF-8 encoded bytes.
+func (p *Profile) NewTransformer() *Transformer {
+ var ts []transform.Transformer
+
+ // These transforms are applied in the order defined in
+ // https://tools.ietf.org/html/rfc7564#section-7
+
+ // RFC 8266 ยง2.1:
+ //
+ // Implementation experience has shown that applying the rules for the
+ // Nickname profile is not an idempotent procedure for all code points.
+ // Therefore, an implementation SHOULD apply the rules repeatedly until
+ // the output string is stable; if the output string does not stabilize
+ // after reapplying the rules three (3) additional times after the first
+ // application, the implementation SHOULD terminate application of the
+ // rules and reject the input string as invalid.
+ //
+ // There is no known string that will change indefinitely, so repeat 4 times
+ // and rely on the Span method to keep things relatively performant.
+ r := 1
+ if p.options.repeat {
+ r = 4
+ }
+ for ; r > 0; r-- {
+ if p.options.foldWidth {
+ ts = append(ts, width.Fold)
+ }
+
+ for _, f := range p.options.additional {
+ ts = append(ts, f())
+ }
+
+ if p.options.cases != nil {
+ ts = append(ts, p.options.cases)
+ }
+
+ ts = append(ts, p.options.norm)
+
+ if p.options.bidiRule {
+ ts = append(ts, bidirule.New())
+ }
+
+ ts = append(ts, &checker{p: p, allowed: p.Allowed()})
+ }
+
+ // TODO: Add the disallow empty rule with a dummy transformer?
+
+ return &Transformer{transform.Chain(ts...)}
+}
+
+var errEmptyString = errors.New("precis: transformation resulted in empty string")
+
+type buffers struct {
+ src []byte
+ buf [2][]byte
+ next int
+}
+
+func (b *buffers) apply(t transform.SpanningTransformer) (err error) {
+ n, err := t.Span(b.src, true)
+ if err != transform.ErrEndOfSpan {
+ return err
+ }
+ x := b.next & 1
+ if b.buf[x] == nil {
+ b.buf[x] = make([]byte, 0, 8+len(b.src)+len(b.src)>>2)
+ }
+ span := append(b.buf[x][:0], b.src[:n]...)
+ b.src, _, err = transform.Append(t, span, b.src[n:])
+ b.buf[x] = b.src
+ b.next++
+ return err
+}
+
+// Pre-allocate transformers when possible. In some cases this avoids allocation.
+var (
+ foldWidthT transform.SpanningTransformer = width.Fold
+ lowerCaseT transform.SpanningTransformer = cases.Lower(language.Und, cases.HandleFinalSigma(false))
+)
+
+// TODO: make this a method on profile.
+
+func (b *buffers) enforce(p *Profile, src []byte, comparing bool) (str []byte, err error) {
+ b.src = src
+
+ ascii := true
+ for _, c := range src {
+ if c >= utf8.RuneSelf {
+ ascii = false
+ break
+ }
+ }
+ // ASCII fast path.
+ if ascii {
+ for _, f := range p.options.additional {
+ if err = b.apply(f()); err != nil {
+ return nil, err
+ }
+ }
+ switch {
+ case p.options.asciiLower || (comparing && p.options.ignorecase):
+ for i, c := range b.src {
+ if 'A' <= c && c <= 'Z' {
+ b.src[i] = c ^ 1<<5
+ }
+ }
+ case p.options.cases != nil:
+ b.apply(p.options.cases)
+ }
+ c := checker{p: p}
+ if _, err := c.span(b.src, true); err != nil {
+ return nil, err
+ }
+ if p.disallow != nil {
+ for _, c := range b.src {
+ if p.disallow.Contains(rune(c)) {
+ return nil, errDisallowedRune
+ }
+ }
+ }
+ if p.options.disallowEmpty && len(b.src) == 0 {
+ return nil, errEmptyString
+ }
+ return b.src, nil
+ }
+
+ // These transforms are applied in the order defined in
+ // https://tools.ietf.org/html/rfc8264#section-7
+
+ r := 1
+ if p.options.repeat {
+ r = 4
+ }
+ for ; r > 0; r-- {
+ // TODO: allow different width transforms options.
+ if p.options.foldWidth || (p.options.ignorecase && comparing) {
+ b.apply(foldWidthT)
+ }
+ for _, f := range p.options.additional {
+ if err = b.apply(f()); err != nil {
+ return nil, err
+ }
+ }
+ if p.options.cases != nil {
+ b.apply(p.options.cases)
+ }
+ if comparing && p.options.ignorecase {
+ b.apply(lowerCaseT)
+ }
+ b.apply(p.norm)
+ if p.options.bidiRule && !bidirule.Valid(b.src) {
+ return nil, bidirule.ErrInvalid
+ }
+ c := checker{p: p}
+ if _, err := c.span(b.src, true); err != nil {
+ return nil, err
+ }
+ if p.disallow != nil {
+ for i := 0; i < len(b.src); {
+ r, size := utf8.DecodeRune(b.src[i:])
+ if p.disallow.Contains(r) {
+ return nil, errDisallowedRune
+ }
+ i += size
+ }
+ }
+ if p.options.disallowEmpty && len(b.src) == 0 {
+ return nil, errEmptyString
+ }
+ }
+ return b.src, nil
+}
+
+// Append appends the result of applying p to src writing the result to dst.
+// It returns an error if the input string is invalid.
+func (p *Profile) Append(dst, src []byte) ([]byte, error) {
+ var buf buffers
+ b, err := buf.enforce(p, src, false)
+ if err != nil {
+ return nil, err
+ }
+ return append(dst, b...), nil
+}
+
+func processBytes(p *Profile, b []byte, key bool) ([]byte, error) {
+ var buf buffers
+ b, err := buf.enforce(p, b, key)
+ if err != nil {
+ return nil, err
+ }
+ if buf.next == 0 {
+ c := make([]byte, len(b))
+ copy(c, b)
+ return c, nil
+ }
+ return b, nil
+}
+
+// Bytes returns a new byte slice with the result of applying the profile to b.
+func (p *Profile) Bytes(b []byte) ([]byte, error) {
+ return processBytes(p, b, false)
+}
+
+// AppendCompareKey appends the result of applying p to src (including any
+// optional rules to make strings comparable or useful in a map key such as
+// applying lowercasing) writing the result to dst. It returns an error if the
+// input string is invalid.
+func (p *Profile) AppendCompareKey(dst, src []byte) ([]byte, error) {
+ var buf buffers
+ b, err := buf.enforce(p, src, true)
+ if err != nil {
+ return nil, err
+ }
+ return append(dst, b...), nil
+}
+
+func processString(p *Profile, s string, key bool) (string, error) {
+ var buf buffers
+ b, err := buf.enforce(p, []byte(s), key)
+ if err != nil {
+ return "", err
+ }
+ return string(b), nil
+}
+
+// String returns a string with the result of applying the profile to s.
+func (p *Profile) String(s string) (string, error) {
+ return processString(p, s, false)
+}
+
+// CompareKey returns a string that can be used for comparison, hashing, or
+// collation.
+func (p *Profile) CompareKey(s string) (string, error) {
+ return processString(p, s, true)
+}
+
+// Compare enforces both strings, and then compares them for bit-string identity
+// (byte-for-byte equality). If either string cannot be enforced, the comparison
+// is false.
+func (p *Profile) Compare(a, b string) bool {
+ var buf buffers
+
+ akey, err := buf.enforce(p, []byte(a), true)
+ if err != nil {
+ return false
+ }
+
+ buf = buffers{}
+ bkey, err := buf.enforce(p, []byte(b), true)
+ if err != nil {
+ return false
+ }
+
+ return bytes.Compare(akey, bkey) == 0
+}
+
+// Allowed returns a runes.Set containing every rune that is a member of the
+// underlying profile's string class and not disallowed by any profile specific
+// rules.
+func (p *Profile) Allowed() runes.Set {
+ if p.options.disallow != nil {
+ return runes.Predicate(func(r rune) bool {
+ return p.class.Contains(r) && !p.options.disallow.Contains(r)
+ })
+ }
+ return p.class
+}
+
+type checker struct {
+ p *Profile
+ allowed runes.Set
+
+ beforeBits catBitmap
+ termBits catBitmap
+ acceptBits catBitmap
+}
+
+func (c *checker) Reset() {
+ c.beforeBits = 0
+ c.termBits = 0
+ c.acceptBits = 0
+}
+
+func (c *checker) span(src []byte, atEOF bool) (n int, err error) {
+ for n < len(src) {
+ e, sz := dpTrie.lookup(src[n:])
+ d := categoryTransitions[category(e&catMask)]
+ if sz == 0 {
+ if !atEOF {
+ return n, transform.ErrShortSrc
+ }
+ return n, errDisallowedRune
+ }
+ doLookAhead := false
+ if property(e) < c.p.class.validFrom {
+ if d.rule == nil {
+ return n, errDisallowedRune
+ }
+ doLookAhead, err = d.rule(c.beforeBits)
+ if err != nil {
+ return n, err
+ }
+ }
+ c.beforeBits &= d.keep
+ c.beforeBits |= d.set
+ if c.termBits != 0 {
+ // We are currently in an unterminated lookahead.
+ if c.beforeBits&c.termBits != 0 {
+ c.termBits = 0
+ c.acceptBits = 0
+ } else if c.beforeBits&c.acceptBits == 0 {
+ // Invalid continuation of the unterminated lookahead sequence.
+ return n, errContext
+ }
+ }
+ if doLookAhead {
+ if c.termBits != 0 {
+ // A previous lookahead run has not been terminated yet.
+ return n, errContext
+ }
+ c.termBits = d.term
+ c.acceptBits = d.accept
+ }
+ n += sz
+ }
+ if m := c.beforeBits >> finalShift; c.beforeBits&m != m || c.termBits != 0 {
+ err = errContext
+ }
+ return n, err
+}
+
+// TODO: we may get rid of this transform if transform.Chain understands
+// something like a Spanner interface.
+func (c checker) Transform(dst, src []byte, atEOF bool) (nDst, nSrc int, err error) {
+ short := false
+ if len(dst) < len(src) {
+ src = src[:len(dst)]
+ atEOF = false
+ short = true
+ }
+ nSrc, err = c.span(src, atEOF)
+ nDst = copy(dst, src[:nSrc])
+ if short && (err == transform.ErrShortSrc || err == nil) {
+ err = transform.ErrShortDst
+ }
+ return nDst, nSrc, err
+}