forked from Pritoj/enmime
/
charsets.go
311 lines (302 loc) · 15.7 KB
/
charsets.go
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package coding
import (
"bytes"
"fmt"
"io"
"io/ioutil"
"regexp"
"strings"
"golang.org/x/text/encoding"
"golang.org/x/text/encoding/charmap"
"golang.org/x/text/encoding/japanese"
"golang.org/x/text/encoding/korean"
"golang.org/x/text/encoding/simplifiedchinese"
"golang.org/x/text/encoding/traditionalchinese"
"golang.org/x/text/encoding/unicode"
"golang.org/x/text/transform"
)
const utf8 = "utf-8"
// encodings is based on golang.org/x/net/html/charset/table.go
var encodings = map[string]struct {
e encoding.Encoding
name string
}{
"unicode-1-1-utf-8": {encoding.Nop, utf8},
"utf-8": {encoding.Nop, utf8},
"utf8": {encoding.Nop, utf8},
"866": {charmap.CodePage866, "ibm866"},
"cp866": {charmap.CodePage866, "ibm866"},
"csibm866": {charmap.CodePage866, "ibm866"},
"ibm866": {charmap.CodePage866, "ibm866"},
"csisolatin2": {charmap.ISO8859_2, "iso-8859-2"},
"iso-8859-2": {charmap.ISO8859_2, "iso-8859-2"},
"iso-ir-101": {charmap.ISO8859_2, "iso-8859-2"},
"iso8859-2": {charmap.ISO8859_2, "iso-8859-2"},
"iso88592": {charmap.ISO8859_2, "iso-8859-2"},
"iso_8859-2": {charmap.ISO8859_2, "iso-8859-2"},
"iso_8859-2:1987": {charmap.ISO8859_2, "iso-8859-2"},
"l2": {charmap.ISO8859_2, "iso-8859-2"},
"latin2": {charmap.ISO8859_2, "iso-8859-2"},
"csisolatin3": {charmap.ISO8859_3, "iso-8859-3"},
"iso-8859-3": {charmap.ISO8859_3, "iso-8859-3"},
"iso-ir-109": {charmap.ISO8859_3, "iso-8859-3"},
"iso8859-3": {charmap.ISO8859_3, "iso-8859-3"},
"iso88593": {charmap.ISO8859_3, "iso-8859-3"},
"iso_8859-3": {charmap.ISO8859_3, "iso-8859-3"},
"iso_8859-3:1988": {charmap.ISO8859_3, "iso-8859-3"},
"l3": {charmap.ISO8859_3, "iso-8859-3"},
"latin3": {charmap.ISO8859_3, "iso-8859-3"},
"csisolatin4": {charmap.ISO8859_4, "iso-8859-4"},
"iso-8859-4": {charmap.ISO8859_4, "iso-8859-4"},
"iso-ir-110": {charmap.ISO8859_4, "iso-8859-4"},
"iso8859-4": {charmap.ISO8859_4, "iso-8859-4"},
"iso88594": {charmap.ISO8859_4, "iso-8859-4"},
"iso_8859-4": {charmap.ISO8859_4, "iso-8859-4"},
"iso_8859-4:1988": {charmap.ISO8859_4, "iso-8859-4"},
"l4": {charmap.ISO8859_4, "iso-8859-4"},
"latin4": {charmap.ISO8859_4, "iso-8859-4"},
"csisolatincyrillic": {charmap.ISO8859_5, "iso-8859-5"},
"cyrillic": {charmap.ISO8859_5, "iso-8859-5"},
"iso-8859-5": {charmap.ISO8859_5, "iso-8859-5"},
"iso-ir-144": {charmap.ISO8859_5, "iso-8859-5"},
"iso8859-5": {charmap.ISO8859_5, "iso-8859-5"},
"iso88595": {charmap.ISO8859_5, "iso-8859-5"},
"iso_8859-5": {charmap.ISO8859_5, "iso-8859-5"},
"iso_8859-5:1988": {charmap.ISO8859_5, "iso-8859-5"},
"arabic": {charmap.ISO8859_6, "iso-8859-6"},
"asmo-708": {charmap.ISO8859_6, "iso-8859-6"},
"csiso88596e": {charmap.ISO8859_6, "iso-8859-6"},
"csiso88596i": {charmap.ISO8859_6, "iso-8859-6"},
"csisolatinarabic": {charmap.ISO8859_6, "iso-8859-6"},
"ecma-114": {charmap.ISO8859_6, "iso-8859-6"},
"iso-8859-6": {charmap.ISO8859_6, "iso-8859-6"},
"iso-8859-6-e": {charmap.ISO8859_6, "iso-8859-6"},
"iso-8859-6-i": {charmap.ISO8859_6, "iso-8859-6"},
"iso-ir-127": {charmap.ISO8859_6, "iso-8859-6"},
"iso8859-6": {charmap.ISO8859_6, "iso-8859-6"},
"iso88596": {charmap.ISO8859_6, "iso-8859-6"},
"iso_8859-6": {charmap.ISO8859_6, "iso-8859-6"},
"iso_8859-6:1987": {charmap.ISO8859_6, "iso-8859-6"},
"csisolatingreek": {charmap.ISO8859_7, "iso-8859-7"},
"ecma-118": {charmap.ISO8859_7, "iso-8859-7"},
"elot_928": {charmap.ISO8859_7, "iso-8859-7"},
"greek": {charmap.ISO8859_7, "iso-8859-7"},
"greek8": {charmap.ISO8859_7, "iso-8859-7"},
"iso-8859-7": {charmap.ISO8859_7, "iso-8859-7"},
"iso-ir-126": {charmap.ISO8859_7, "iso-8859-7"},
"iso8859-7": {charmap.ISO8859_7, "iso-8859-7"},
"iso88597": {charmap.ISO8859_7, "iso-8859-7"},
"iso_8859-7": {charmap.ISO8859_7, "iso-8859-7"},
"iso_8859-7:1987": {charmap.ISO8859_7, "iso-8859-7"},
"sun_eu_greek": {charmap.ISO8859_7, "iso-8859-7"},
"csiso88598e": {charmap.ISO8859_8, "iso-8859-8"},
"csisolatinhebrew": {charmap.ISO8859_8, "iso-8859-8"},
"hebrew": {charmap.ISO8859_8, "iso-8859-8"},
"iso-8859-8": {charmap.ISO8859_8, "iso-8859-8"},
"iso-8859-8-e": {charmap.ISO8859_8, "iso-8859-8"},
"iso-ir-138": {charmap.ISO8859_8, "iso-8859-8"},
"iso8859-8": {charmap.ISO8859_8, "iso-8859-8"},
"iso88598": {charmap.ISO8859_8, "iso-8859-8"},
"iso_8859-8": {charmap.ISO8859_8, "iso-8859-8"},
"iso_8859-8:1988": {charmap.ISO8859_8, "iso-8859-8"},
"visual": {charmap.ISO8859_8, "iso-8859-8"},
"csiso88598i": {charmap.ISO8859_8, "iso-8859-8-i"},
"iso-8859-8-i": {charmap.ISO8859_8, "iso-8859-8-i"},
"logical": {charmap.ISO8859_8, "iso-8859-8-i"},
"csisolatin6": {charmap.ISO8859_10, "iso-8859-10"},
"iso-8859-10": {charmap.ISO8859_10, "iso-8859-10"},
"iso-ir-157": {charmap.ISO8859_10, "iso-8859-10"},
"iso8859-10": {charmap.ISO8859_10, "iso-8859-10"},
"iso885910": {charmap.ISO8859_10, "iso-8859-10"},
"l6": {charmap.ISO8859_10, "iso-8859-10"},
"latin6": {charmap.ISO8859_10, "iso-8859-10"},
"iso-8859-13": {charmap.ISO8859_13, "iso-8859-13"},
"iso8859-13": {charmap.ISO8859_13, "iso-8859-13"},
"iso885913": {charmap.ISO8859_13, "iso-8859-13"},
"iso-8859-14": {charmap.ISO8859_14, "iso-8859-14"},
"iso8859-14": {charmap.ISO8859_14, "iso-8859-14"},
"iso885914": {charmap.ISO8859_14, "iso-8859-14"},
"csisolatin9": {charmap.ISO8859_15, "iso-8859-15"},
"iso-8859-15": {charmap.ISO8859_15, "iso-8859-15"},
"iso8859-15": {charmap.ISO8859_15, "iso-8859-15"},
"iso885915": {charmap.ISO8859_15, "iso-8859-15"},
"iso_8859-15": {charmap.ISO8859_15, "iso-8859-15"},
"l9": {charmap.ISO8859_15, "iso-8859-15"},
"iso-8859-16": {charmap.ISO8859_16, "iso-8859-16"},
"cskoi8r": {charmap.KOI8R, "koi8-r"},
"koi": {charmap.KOI8R, "koi8-r"},
"koi8": {charmap.KOI8R, "koi8-r"},
"koi8-r": {charmap.KOI8R, "koi8-r"},
"koi8_r": {charmap.KOI8R, "koi8-r"},
"koi8-u": {charmap.KOI8U, "koi8-u"},
"csmacintosh": {charmap.Macintosh, "macintosh"},
"mac": {charmap.Macintosh, "macintosh"},
"macintosh": {charmap.Macintosh, "macintosh"},
"x-mac-roman": {charmap.Macintosh, "macintosh"},
"dos-874": {charmap.Windows874, "windows-874"},
"iso-8859-11": {charmap.Windows874, "windows-874"},
"iso8859-11": {charmap.Windows874, "windows-874"},
"iso885911": {charmap.Windows874, "windows-874"},
"tis-620": {charmap.Windows874, "windows-874"},
"windows-874": {charmap.Windows874, "windows-874"},
"cp1250": {charmap.Windows1250, "windows-1250"},
"windows-1250": {charmap.Windows1250, "windows-1250"},
"x-cp1250": {charmap.Windows1250, "windows-1250"},
"cp1251": {charmap.Windows1251, "windows-1251"},
"windows-1251": {charmap.Windows1251, "windows-1251"},
"x-cp1251": {charmap.Windows1251, "windows-1251"},
"ansi_x3.4-1968": {charmap.Windows1252, "windows-1252"},
"ascii": {charmap.Windows1252, "windows-1252"},
"cp1252": {charmap.Windows1252, "windows-1252"},
"cp819": {charmap.Windows1252, "windows-1252"},
"csisolatin1": {charmap.Windows1252, "windows-1252"},
"ibm819": {charmap.Windows1252, "windows-1252"},
"iso-8859-1": {charmap.Windows1252, "windows-1252"},
"iso-ir-100": {charmap.Windows1252, "windows-1252"},
"iso8859-1": {charmap.Windows1252, "windows-1252"},
"iso8859_1": {charmap.Windows1252, "windows-1252"},
"iso88591": {charmap.Windows1252, "windows-1252"},
"iso_8859-1": {charmap.Windows1252, "windows-1252"},
"iso_8859-1:1987": {charmap.Windows1252, "windows-1252"},
"l1": {charmap.Windows1252, "windows-1252"},
"latin1": {charmap.Windows1252, "windows-1252"},
"us-ascii": {charmap.Windows1252, "windows-1252"},
"windows-1252": {charmap.Windows1252, "windows-1252"},
"x-cp1252": {charmap.Windows1252, "windows-1252"},
"cp1253": {charmap.Windows1253, "windows-1253"},
"windows-1253": {charmap.Windows1253, "windows-1253"},
"x-cp1253": {charmap.Windows1253, "windows-1253"},
"cp1254": {charmap.Windows1254, "windows-1254"},
"csisolatin5": {charmap.Windows1254, "windows-1254"},
"iso-8859-9": {charmap.Windows1254, "windows-1254"},
"iso-ir-148": {charmap.Windows1254, "windows-1254"},
"iso8859-9": {charmap.Windows1254, "windows-1254"},
"iso88599": {charmap.Windows1254, "windows-1254"},
"iso_8859-9": {charmap.Windows1254, "windows-1254"},
"iso_8859-9:1989": {charmap.Windows1254, "windows-1254"},
"l5": {charmap.Windows1254, "windows-1254"},
"latin5": {charmap.Windows1254, "windows-1254"},
"windows-1254": {charmap.Windows1254, "windows-1254"},
"x-cp1254": {charmap.Windows1254, "windows-1254"},
"cp1255": {charmap.Windows1255, "windows-1255"},
"windows-1255": {charmap.Windows1255, "windows-1255"},
"x-cp1255": {charmap.Windows1255, "windows-1255"},
"cp1256": {charmap.Windows1256, "windows-1256"},
"windows-1256": {charmap.Windows1256, "windows-1256"},
"x-cp1256": {charmap.Windows1256, "windows-1256"},
"cp1257": {charmap.Windows1257, "windows-1257"},
"windows-1257": {charmap.Windows1257, "windows-1257"},
"x-cp1257": {charmap.Windows1257, "windows-1257"},
"cp1258": {charmap.Windows1258, "windows-1258"},
"windows-1258": {charmap.Windows1258, "windows-1258"},
"x-cp1258": {charmap.Windows1258, "windows-1258"},
"x-mac-cyrillic": {charmap.MacintoshCyrillic, "x-mac-cyrillic"},
"x-mac-ukrainian": {charmap.MacintoshCyrillic, "x-mac-cyrillic"},
"chinese": {simplifiedchinese.GBK, "gbk"},
"csgb2312": {simplifiedchinese.GBK, "gbk"},
"csiso58gb231280": {simplifiedchinese.GBK, "gbk"},
"gb2312": {simplifiedchinese.GBK, "gbk"},
"gb_2312": {simplifiedchinese.GBK, "gbk"},
"gb_2312-80": {simplifiedchinese.GBK, "gbk"},
"gbk": {simplifiedchinese.GBK, "gbk"},
"iso-ir-58": {simplifiedchinese.GBK, "gbk"},
"x-gbk": {simplifiedchinese.GBK, "gbk"},
"gb18030": {simplifiedchinese.GB18030, "gb18030"},
"hz-gb-2312": {simplifiedchinese.HZGB2312, "hz-gb-2312"},
"big5": {traditionalchinese.Big5, "big5"},
"big5-hkscs": {traditionalchinese.Big5, "big5"},
"cn-big5": {traditionalchinese.Big5, "big5"},
"csbig5": {traditionalchinese.Big5, "big5"},
"x-x-big5": {traditionalchinese.Big5, "big5"},
"cseucpkdfmtjapanese": {japanese.EUCJP, "euc-jp"},
"euc-jp": {japanese.EUCJP, "euc-jp"},
"x-euc-jp": {japanese.EUCJP, "euc-jp"},
"csiso2022jp": {japanese.ISO2022JP, "iso-2022-jp"},
"iso-2022-jp": {japanese.ISO2022JP, "iso-2022-jp"},
"csshiftjis": {japanese.ShiftJIS, "shift_jis"},
"ms_kanji": {japanese.ShiftJIS, "shift_jis"},
"shift-jis": {japanese.ShiftJIS, "shift_jis"},
"shift_jis": {japanese.ShiftJIS, "shift_jis"},
"sjis": {japanese.ShiftJIS, "shift_jis"},
"windows-31j": {japanese.ShiftJIS, "shift_jis"},
"x-sjis": {japanese.ShiftJIS, "shift_jis"},
"cseuckr": {korean.EUCKR, "euc-kr"},
"csksc56011987": {korean.EUCKR, "euc-kr"},
"euc-kr": {korean.EUCKR, "euc-kr"},
"iso-ir-149": {korean.EUCKR, "euc-kr"},
"korean": {korean.EUCKR, "euc-kr"},
"ks_c_5601-1987": {korean.EUCKR, "euc-kr"},
"ks_c_5601-1989": {korean.EUCKR, "euc-kr"},
"ksc5601": {korean.EUCKR, "euc-kr"},
"ksc_5601": {korean.EUCKR, "euc-kr"},
"windows-949": {korean.EUCKR, "euc-kr"},
"csiso2022kr": {encoding.Replacement, "replacement"},
"iso-2022-kr": {encoding.Replacement, "replacement"},
"iso-2022-cn": {encoding.Replacement, "replacement"},
"iso-2022-cn-ext": {encoding.Replacement, "replacement"},
"utf-16be": {unicode.UTF16(unicode.BigEndian, unicode.IgnoreBOM), "utf-16be"},
"utf-16": {unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM), "utf-16le"},
"utf-16le": {unicode.UTF16(unicode.LittleEndian, unicode.IgnoreBOM), "utf-16le"},
"x-user-defined": {charmap.XUserDefined, "x-user-defined"},
"iso646-us": {charmap.Windows1252, "windows-1252"}, // ISO646 isn't us-ascii but 1991 version is.
"iso: western": {charmap.Windows1252, "windows-1252"}, // same as iso-8859-1
"we8iso8859p1": {charmap.Windows1252, "windows-1252"}, // same as iso-8859-1
"iso=8859-1": {charmap.Windows1252, "windows-1252"}, // same as iso-8859-1
"cp936": {simplifiedchinese.GBK, "gbk"}, // same as gb2312
"cp850": {charmap.CodePage850, "cp850"},
"cp-850": {charmap.CodePage850, "cp850"},
"ibm850": {charmap.CodePage850, "cp850"},
"136": {traditionalchinese.Big5, "big5"}, // same as chinese big5
}
var metaTagCharsetRegexp = regexp.MustCompile(
`(?i)<meta.*charset="?\s*(?P<charset>[a-zA-Z0-9_.:-]+)\s*"?`)
var metaTagCharsetIndex int
func init() {
// Find the submatch index for charset in metaTagCharsetRegexp
for i, name := range metaTagCharsetRegexp.SubexpNames() {
if name == "charset" {
metaTagCharsetIndex = i
break
}
}
}
// ConvertToUTF8String uses the provided charset to decode a slice of bytes into a normal
// UTF-8 string.
func ConvertToUTF8String(charset string, textBytes []byte) (string, error) {
if strings.ToLower(charset) == utf8 {
return string(textBytes), nil
}
csentry, ok := encodings[strings.ToLower(charset)]
if !ok {
return "", fmt.Errorf("Unsupported charset %q", charset)
}
input := bytes.NewReader(textBytes)
reader := transform.NewReader(input, csentry.e.NewDecoder())
output, err := ioutil.ReadAll(reader)
if err != nil {
return "", err
}
return string(output), nil
}
// NewCharsetReader generates charset-conversion readers, converting from the provided charset into
// UTF-8. CharsetReader is a factory signature defined by Go's mime.WordDecoder.
//
// This function is similar to: https://godoc.org/golang.org/x/net/html/charset#NewReaderLabel
func NewCharsetReader(charset string, input io.Reader) (io.Reader, error) {
if strings.ToLower(charset) == utf8 {
return input, nil
}
csentry, ok := encodings[strings.ToLower(charset)]
if !ok {
return nil, fmt.Errorf("Unsupported charset %q", charset)
}
return transform.NewReader(input, csentry.e.NewDecoder()), nil
}
// FindCharsetInHTML looks for charset in the HTML meta tag (v4.01 and v5).
func FindCharsetInHTML(html string) string {
charsetMatches := metaTagCharsetRegexp.FindAllStringSubmatch(html, -1)
if len(charsetMatches) > 0 {
return charsetMatches[0][metaTagCharsetIndex]
}
return ""
}