From 8f91c777559748fa6e857d9fc1f4ae079a532813 Mon Sep 17 00:00:00 2001 From: Christopher Speller Date: Mon, 3 Oct 2016 16:03:15 -0400 Subject: Adding ability to serve TLS directly from Mattermost server (#4119) --- vendor/github.com/miekg/dns/idn/punycode.go | 373 ++++++++++++++++++++++++++++ 1 file changed, 373 insertions(+) create mode 100644 vendor/github.com/miekg/dns/idn/punycode.go (limited to 'vendor/github.com/miekg/dns/idn/punycode.go') 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 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 +} -- cgit v1.2.3-1-g7c22