1 files changed, 227 insertions, 0 deletions
diff --git a/vendor/github.com/mattermost/rsc/imap/decode.go b/vendor/github.com/mattermost/rsc/imap/decode.go
new file mode 100644
index 000000000..ebeb1d7d7
--- /dev/null
+++ b/vendor/github.com/mattermost/rsc/imap/decode.go
@@ -0,0 +1,227 @@
+package imap
+
+import (
+	"bytes"
+	"encoding/base64"
+	"strings"
+	"unicode"
+)
+
+func decode2047chunk(s string) (conv []byte, rest string, ok bool) {
+	// s is =?...
+	// and should be =?charset?e?text?=
+	j := strings.Index(s[2:], "?")
+	if j < 0 {
+		return
+	}
+	j += 2
+	if j+2 >= len(s) || s[j+2] != '?' {
+		return
+	}
+	k := strings.Index(s[j+3:], "?=")
+	if k < 0 {
+		return
+	}
+	k += j + 3
+
+	charset, enc, text, rest := s[2:j], s[j+1], s[j+3:k], s[k+2:]
+	var encoding string
+	switch enc {
+	default:
+		return
+	case 'q', 'Q':
+		encoding = "quoted-printable"
+	case 'b', 'B':
+		encoding = "base64"
+	}
+
+	dat := decodeText([]byte(text), encoding, charset, true)
+	if dat == nil {
+		return
+	}
+	return dat, rest, true
+}
+
+func decodeQP(dat []byte, underscore bool) []byte {
+	out := make([]byte, len(dat))
+	w := 0
+	for i := 0; i < len(dat); i++ {
+		c := dat[i]
+		if underscore && c == '_' {
+			out[w] = ' '
+			w++
+			continue
+		}
+		if c == '\r' {
+			continue
+		}
+		if c == '=' {
+			if i+1 < len(dat) && dat[i+1] == '\n' {
+				i++
+				continue
+			}
+			if i+2 < len(dat) && dat[i+1] == '\r' && dat[i+2] == '\n' {
+				i += 2
+				continue
+			}
+			if i+2 < len(dat) {
+				v := unhex(dat[i+1])<<4 | unhex(dat[i+2])
+				if v >= 0 {
+					out[w] = byte(v)
+					w++
+					i += 2
+					continue
+				}
+			}
+		}
+		out[w] = c
+		w++
+	}
+	return out[:w]
+}
+
+func nocrnl(dat []byte) []byte {
+	w := 0
+	for _, c := range dat {
+		if c != '\r' && c != '\n' {
+			dat[w] = c
+			w++
+		}
+	}
+	return dat[:w]
+}
+
+func decode64(dat []byte) []byte {
+	out := make([]byte, len(dat))
+	copy(out, dat)
+	out = nocrnl(out)
+	n, err := base64.StdEncoding.Decode(out, out)
+	if err != nil {
+		return nil
+	}
+	return out[:n]
+}
+
+func decodeText(dat []byte, encoding, charset string, underscore bool) []byte {
+	odat := dat
+	switch strlwr(encoding) {
+	case "quoted-printable":
+		dat = decodeQP(dat, underscore)
+	case "base64":
+		dat = decode64(dat)
+	}
+	if dat == nil {
+		return nil
+	}
+	if bytes.IndexByte(dat, '\r') >= 0 {
+		if &odat[0] == &dat[0] {
+			dat = append([]byte(nil), dat...)
+		}
+		dat = nocr(dat)
+	}
+
+	charset = strlwr(charset)
+	if charset == "utf-8" || charset == "us-ascii" {
+		return dat
+	}
+	if charset == "iso-8859-1" {
+		// Avoid allocation for iso-8859-1 that is really just ascii.
+		for _, c := range dat {
+			if c >= 0x80 {
+				goto NeedConv
+			}
+		}
+		return dat
+	NeedConv:
+	}
+
+	// TODO: big5, iso-2022-jp
+
+	tab := convtab[charset]
+	if tab == nil {
+		return dat
+	}
+	var b bytes.Buffer
+	for _, c := range dat {
+		if tab[c] < 0 {
+			b.WriteRune(unicode.ReplacementChar)
+		} else {
+			b.WriteRune(tab[c])
+		}
+	}
+	return b.Bytes()
+}
+
+var convtab = map[string]*[256]rune{
+	"iso-8859-1":   &tab_iso8859_1,
+	"iso-8859-2":   &tab_iso8859_2,
+	"iso-8859-3":   &tab_iso8859_3,
+	"iso-8859-4":   &tab_iso8859_4,
+	"iso-8859-5":   &tab_iso8859_5,
+	"iso-8859-6":   &tab_iso8859_6,
+	"iso-8859-7":   &tab_iso8859_7,
+	"iso-8859-8":   &tab_iso8859_8,
+	"iso-8859-9":   &tab_iso8859_9,
+	"iso-8859-10":  &tab_iso8859_10,
+	"iso-8859-15":  &tab_iso8859_15,
+	"koi8-r":       &tab_koi8,
+	"windows-1250": &tab_cp1250,
+	"windows-1251": &tab_cp1251,
+	"windows-1252": &tab_cp1252,
+	"windows-1253": &tab_cp1253,
+	"windows-1254": &tab_cp1254,
+	"windows-1255": &tab_cp1255,
+	"windows-1256": &tab_cp1256,
+	"windows-1257": &tab_cp1257,
+	"windows-1258": &tab_cp1258,
+}
+
+func unrfc2047(s string) string {
+	if !strings.Contains(s, "=?") {
+		return s
+	}
+	var buf bytes.Buffer
+	for {
+		// =?charset?e?text?=
+		i := strings.Index(s, "=?")
+		if i < 0 {
+			break
+		}
+		conv, rest, ok := decode2047chunk(s[i:])
+		if !ok {
+			buf.WriteString(s[:i+2])
+			s = s[i+2:]
+			continue
+		}
+		buf.WriteString(s[:i])
+		buf.Write(conv)
+		s = rest
+	}
+	buf.WriteString(s)
+	return buf.String()
+}
+
+func lwr(c rune) rune {
+	if 'A' <= c && c <= 'Z' {
+		return c + 'a' - 'A'
+	}
+	return c
+}
+
+func strlwr(s string) string {
+	return strings.Map(lwr, s)
+}
+
+func unhex(c byte) int {
+	switch {
+	case '0' <= c && c <= '9':
+		return int(c) - '0'
+	case 'a' <= c && c <= 'f':
+		return int(c) - 'a' + 10
+	case 'A' <= c && c <= 'F':
+		return int(c) - 'A' + 10
+	}
+	return -1
+}
+
+// TODO: Will need modified UTF-7 eventually.