1 files changed, 373 insertions, 0 deletions
diff --git a/vendor/github.com/miekg/dns/idn/punycode.go b/vendor/github.com/miekg/dns/idn/punycode.go
new file mode 100644
index 000000000..7e5c263fc
--- /dev/null
+++ b/vendor/github.com/miekg/dns/idn/punycode.go
@@ -0,0 +1,373 @@
+// Package idn implements encoding from and to punycode as speficied by RFC 3492.
+package idn
+
+import (
+	"bytes"
+	"strings"
+	"unicode"
+	"unicode/utf8"
+
+	"github.com/miekg/dns"
+)
+
+// Implementation idea from RFC itself and from from IDNA::Punycode created by
+// Tatsuhiko Miyagawa <miyagawa@bulknews.net> and released under Perl Artistic
+// License in 2002.
+
+const (
+	_MIN  rune = 1
+	_MAX  rune = 26
+	_SKEW rune = 38
+	_BASE rune = 36
+	_BIAS rune = 72
+	_N    rune = 128
+	_DAMP rune = 700
+
+	_DELIMITER = '-'
+	_PREFIX    = "xn--"
+)
+
+// ToPunycode converts unicode domain names to DNS-appropriate punycode names.
+// This function will return an empty string result for domain names with
+// invalid unicode strings. This function expects domain names in lowercase.
+func ToPunycode(s string) string {
+	// Early check to see if encoding is needed.
+	// This will prevent making heap allocations when not needed.
+	if !needToPunycode(s) {
+		return s
+	}
+
+	tokens := dns.SplitDomainName(s)
+	switch {
+	case s == "":
+		return ""
+	case tokens == nil: // s == .
+		return "."
+	case s[len(s)-1] == '.':
+		tokens = append(tokens, "")
+	}
+
+	for i := range tokens {
+		t := encode([]byte(tokens[i]))
+		if t == nil {
+			return ""
+		}
+		tokens[i] = string(t)
+	}
+	return strings.Join(tokens, ".")
+}
+
+// FromPunycode returns unicode domain name from provided punycode string.
+// This function expects punycode strings in lowercase.
+func FromPunycode(s string) string {
+	// Early check to see if decoding is needed.
+	// This will prevent making heap allocations when not needed.
+	if !needFromPunycode(s) {
+		return s
+	}
+
+	tokens := dns.SplitDomainName(s)
+	switch {
+	case s == "":
+		return ""
+	case tokens == nil: // s == .
+		return "."
+	case s[len(s)-1] == '.':
+		tokens = append(tokens, "")
+	}
+	for i := range tokens {
+		tokens[i] = string(decode([]byte(tokens[i])))
+	}
+	return strings.Join(tokens, ".")
+}
+
+// digitval converts single byte into meaningful value that's used to calculate decoded unicode character.
+const errdigit = 0xffff
+
+func digitval(code rune) rune {
+	switch {
+	case code >= 'A' && code <= 'Z':
+		return code - 'A'
+	case code >= 'a' && code <= 'z':
+		return code - 'a'
+	case code >= '0' && code <= '9':
+		return code - '0' + 26
+	}
+	return errdigit
+}
+
+// lettercode finds BASE36 byte (a-z0-9) based on calculated number.
+func lettercode(digit rune) rune {
+	switch {
+	case digit >= 0 && digit <= 25:
+		return digit + 'a'
+	case digit >= 26 && digit <= 36:
+		return digit - 26 + '0'
+	}
+	panic("dns: not reached")
+}
+
+// adapt calculates next bias to be used for next iteration delta.
+func adapt(delta rune, numpoints int, firsttime bool) rune {
+	if firsttime {
+		delta /= _DAMP
+	} else {
+		delta /= 2
+	}
+
+	var k rune
+	for delta = delta + delta/rune(numpoints); delta > (_BASE-_MIN)*_MAX/2; k += _BASE {
+		delta /= _BASE - _MIN
+	}
+
+	return k + ((_BASE-_MIN+1)*delta)/(delta+_SKEW)
+}
+
+// next finds minimal rune (one with lowest codepoint value) that should be equal or above boundary.
+func next(b []rune, boundary rune) rune {
+	if len(b) == 0 {
+		panic("dns: invalid set of runes to determine next one")
+	}
+	m := b[0]
+	for _, x := range b[1:] {
+		if x >= boundary && (m < boundary || x < m) {
+			m = x
+		}
+	}
+	return m
+}
+
+// preprune converts unicode rune to lower case. At this time it's not
+// supporting all things described in RFCs.
+func preprune(r rune) rune {
+	if unicode.IsUpper(r) {
+		r = unicode.ToLower(r)
+	}
+	return r
+}
+
+// tfunc is a function that helps calculate each character weight.
+func tfunc(k, bias rune) rune {
+	switch {
+	case k <= bias:
+		return _MIN
+	case k >= bias+_MAX:
+		return _MAX
+	}
+	return k - bias
+}
+
+// needToPunycode returns true for strings that require punycode encoding
+// (contain unicode characters).
+func needToPunycode(s string) bool {
+	// This function is very similar to bytes.Runes. We don't use bytes.Runes
+	// because it makes a heap allocation that's not needed here.
+	for i := 0; len(s) > 0; i++ {
+		r, l := utf8.DecodeRuneInString(s)
+		if r > 0x7f {
+			return true
+		}
+		s = s[l:]
+	}
+	return false
+}
+
+// needFromPunycode returns true for strings that require punycode decoding.
+func needFromPunycode(s string) bool {
+	if s == "." {
+		return false
+	}
+
+	off := 0
+	end := false
+	pl := len(_PREFIX)
+	sl := len(s)
+
+	// If s starts with _PREFIX.
+	if sl > pl && s[off:off+pl] == _PREFIX {
+		return true
+	}
+
+	for {
+		// Find the part after the next ".".
+		off, end = dns.NextLabel(s, off)
+		if end {
+			return false
+		}
+		// If this parts starts with _PREFIX.
+		if sl-off > pl && s[off:off+pl] == _PREFIX {
+			return true
+		}
+	}
+}
+
+// encode transforms Unicode input bytes (that represent DNS label) into
+// punycode bytestream. This function would return nil if there's an invalid
+// character in the label.
+func encode(input []byte) []byte {
+	n, bias := _N, _BIAS
+
+	b := bytes.Runes(input)
+	for i := range b {
+		if !isValidRune(b[i]) {
+			return nil
+		}
+
+		b[i] = preprune(b[i])
+	}
+
+	basic := make([]byte, 0, len(b))
+	for _, ltr := range b {
+		if ltr <= 0x7f {
+			basic = append(basic, byte(ltr))
+		}
+	}
+	basiclen := len(basic)
+	fulllen := len(b)
+	if basiclen == fulllen {
+		return basic
+	}
+
+	var out bytes.Buffer
+
+	out.WriteString(_PREFIX)
+	if basiclen > 0 {
+		out.Write(basic)
+		out.WriteByte(_DELIMITER)
+	}
+
+	var (
+		ltr, nextltr rune
+		delta, q     rune // delta calculation (see rfc)
+		t, k, cp     rune // weight and codepoint calculation
+	)
+
+	s := &bytes.Buffer{}
+	for h := basiclen; h < fulllen; n, delta = n+1, delta+1 {
+		nextltr = next(b, n)
+		s.Truncate(0)
+		s.WriteRune(nextltr)
+		delta, n = delta+(nextltr-n)*rune(h+1), nextltr
+
+		for _, ltr = range b {
+			if ltr < n {
+				delta++
+			}
+			if ltr == n {
+				q = delta
+				for k = _BASE; ; k += _BASE {
+					t = tfunc(k, bias)
+					if q < t {
+						break
+					}
+					cp = t + ((q - t) % (_BASE - t))
+					out.WriteRune(lettercode(cp))
+					q = (q - t) / (_BASE - t)
+				}
+
+				out.WriteRune(lettercode(q))
+
+				bias = adapt(delta, h+1, h == basiclen)
+				h, delta = h+1, 0
+			}
+		}
+	}
+	return out.Bytes()
+}
+
+// decode transforms punycode input bytes (that represent DNS label) into Unicode bytestream.
+func decode(b []byte) []byte {
+	src := b // b would move and we need to keep it
+
+	n, bias := _N, _BIAS
+	if !bytes.HasPrefix(b, []byte(_PREFIX)) {
+		return b
+	}
+	out := make([]rune, 0, len(b))
+	b = b[len(_PREFIX):]
+	for pos := len(b) - 1; pos >= 0; pos-- {
+		// only last delimiter is our interest
+		if b[pos] == _DELIMITER {
+			out = append(out, bytes.Runes(b[:pos])...)
+			b = b[pos+1:] // trim source string
+			break
+		}
+	}
+	if len(b) == 0 {
+		return src
+	}
+	var (
+		i, oldi, w rune
+		ch         byte
+		t, digit   rune
+		ln         int
+	)
+
+	for i = 0; len(b) > 0; i++ {
+		oldi, w = i, 1
+		for k := _BASE; len(b) > 0; k += _BASE {
+			ch, b = b[0], b[1:]
+			digit = digitval(rune(ch))
+			if digit == errdigit {
+				return src
+			}
+			i += digit * w
+			if i < 0 {
+				// safety check for rune overflow
+				return src
+			}
+
+			t = tfunc(k, bias)
+			if digit < t {
+				break
+			}
+
+			w *= _BASE - t
+		}
+		ln = len(out) + 1
+		bias = adapt(i-oldi, ln, oldi == 0)
+		n += i / rune(ln)
+		i = i % rune(ln)
+		// insert
+		out = append(out, 0)
+		copy(out[i+1:], out[i:])
+		out[i] = n
+	}
+
+	var ret bytes.Buffer
+	for _, r := range out {
+		ret.WriteRune(r)
+	}
+	return ret.Bytes()
+}
+
+// isValidRune checks if the character is valid. We will look for the
+// character property in the code points list. For now we aren't checking special
+// rules in case of contextual property
+func isValidRune(r rune) bool {
+	return findProperty(r) == propertyPVALID
+}
+
+// findProperty will try to check the code point property of the given
+// character. It will use a binary search algorithm as we have a slice of
+// ordered ranges (average case performance O(log n))
+func findProperty(r rune) property {
+	imin, imax := 0, len(codePoints)
+
+	for imax >= imin {
+		imid := (imin + imax) / 2
+
+		codePoint := codePoints[imid]
+		if (codePoint.start == r && codePoint.end == 0) || (codePoint.start <= r && codePoint.end >= r) {
+			return codePoint.state
+		}
+
+		if (codePoint.end > 0 && codePoint.end < r) || (codePoint.end == 0 && codePoint.start < r) {
+			imin = imid + 1
+		} else {
+			imax = imid - 1
+		}
+	}
+
+	return propertyUnknown
+}