twitst4tz

utf7.js (9215B)

---

 "use strict";
 var Buffer = require("safer-buffer").Buffer;
 
 // UTF-7 codec, according to https://tools.ietf.org/html/rfc2152
 // See also below a UTF-7-IMAP codec, according to http://tools.ietf.org/html/rfc3501#section-5.1.3
 
 exports.utf7 = Utf7Codec;
 exports.unicode11utf7 = 'utf7'; // Alias UNICODE-1-1-UTF-7
 function Utf7Codec(codecOptions, iconv) {
     this.iconv = iconv;
 };
 
 Utf7Codec.prototype.encoder = Utf7Encoder;
 Utf7Codec.prototype.decoder = Utf7Decoder;
 Utf7Codec.prototype.bomAware = true;
 
 
 // -- Encoding
 
 var nonDirectChars = /[^A-Za-z0-9'\(\),-\.\/:\? \n\r\t]+/g;
 
 function Utf7Encoder(options, codec) {
     this.iconv = codec.iconv;
 }
 
 Utf7Encoder.prototype.write = function(str) {
     // Naive implementation.
     // Non-direct chars are encoded as "+<base64>-"; single "+" char is encoded as "+-".
     return Buffer.from(str.replace(nonDirectChars, function(chunk) {
         return "+" + (chunk === '+' ? '' : 
             this.iconv.encode(chunk, 'utf16-be').toString('base64').replace(/=+$/, '')) 
             + "-";
     }.bind(this)));
 }
 
 Utf7Encoder.prototype.end = function() {
 }
 
 
 // -- Decoding
 
 function Utf7Decoder(options, codec) {
     this.iconv = codec.iconv;
     this.inBase64 = false;
     this.base64Accum = '';
 }
 
 var base64Regex = /[A-Za-z0-9\/+]/;
 var base64Chars = [];
 for (var i = 0; i < 256; i++)
     base64Chars[i] = base64Regex.test(String.fromCharCode(i));
 
 var plusChar = '+'.charCodeAt(0), 
     minusChar = '-'.charCodeAt(0),
     andChar = '&'.charCodeAt(0);
 
 Utf7Decoder.prototype.write = function(buf) {
     var res = "", lastI = 0,
         inBase64 = this.inBase64,
         base64Accum = this.base64Accum;
 
     // The decoder is more involved as we must handle chunks in stream.
 
     for (var i = 0; i < buf.length; i++) {
         if (!inBase64) { // We're in direct mode.
             // Write direct chars until '+'
             if (buf[i] == plusChar) {
                 res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
                 lastI = i+1;
                 inBase64 = true;
             }
         } else { // We decode base64.
             if (!base64Chars[buf[i]]) { // Base64 ended.
                 if (i == lastI && buf[i] == minusChar) {// "+-" -> "+"
                     res += "+";
                 } else {
                     var b64str = base64Accum + buf.slice(lastI, i).toString();
                     res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
                 }
 
                 if (buf[i] != minusChar) // Minus is absorbed after base64.
                     i--;
 
                 lastI = i+1;
                 inBase64 = false;
                 base64Accum = '';
             }
         }
     }
 
     if (!inBase64) {
         res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
     } else {
         var b64str = base64Accum + buf.slice(lastI).toString();
 
         var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
         base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
         b64str = b64str.slice(0, canBeDecoded);
 
         res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
     }
 
     this.inBase64 = inBase64;
     this.base64Accum = base64Accum;
 
     return res;
 }
 
 Utf7Decoder.prototype.end = function() {
     var res = "";
     if (this.inBase64 && this.base64Accum.length > 0)
         res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");
 
     this.inBase64 = false;
     this.base64Accum = '';
     return res;
 }
 
 
 // UTF-7-IMAP codec.
 // RFC3501 Sec. 5.1.3 Modified UTF-7 (http://tools.ietf.org/html/rfc3501#section-5.1.3)
 // Differences:
 //  * Base64 part is started by "&" instead of "+"
 //  * Direct characters are 0x20-0x7E, except "&" (0x26)
 //  * In Base64, "," is used instead of "/"
 //  * Base64 must not be used to represent direct characters.
 //  * No implicit shift back from Base64 (should always end with '-')
 //  * String must end in non-shifted position.
 //  * "-&" while in base64 is not allowed.
 
 
 exports.utf7imap = Utf7IMAPCodec;
 function Utf7IMAPCodec(codecOptions, iconv) {
     this.iconv = iconv;
 };
 
 Utf7IMAPCodec.prototype.encoder = Utf7IMAPEncoder;
 Utf7IMAPCodec.prototype.decoder = Utf7IMAPDecoder;
 Utf7IMAPCodec.prototype.bomAware = true;
 
 
 // -- Encoding
 
 function Utf7IMAPEncoder(options, codec) {
     this.iconv = codec.iconv;
     this.inBase64 = false;
     this.base64Accum = Buffer.alloc(6);
     this.base64AccumIdx = 0;
 }
 
 Utf7IMAPEncoder.prototype.write = function(str) {
     var inBase64 = this.inBase64,
         base64Accum = this.base64Accum,
         base64AccumIdx = this.base64AccumIdx,
         buf = Buffer.alloc(str.length*5 + 10), bufIdx = 0;
 
     for (var i = 0; i < str.length; i++) {
         var uChar = str.charCodeAt(i);
         if (0x20 <= uChar && uChar <= 0x7E) { // Direct character or '&'.
             if (inBase64) {
                 if (base64AccumIdx > 0) {
                     bufIdx += buf.write(base64Accum.slice(0, base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
                     base64AccumIdx = 0;
                 }
 
                 buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
                 inBase64 = false;
             }
 
             if (!inBase64) {
                 buf[bufIdx++] = uChar; // Write direct character
 
                 if (uChar === andChar)  // Ampersand -> '&-'
                     buf[bufIdx++] = minusChar;
             }
 
         } else { // Non-direct character
             if (!inBase64) {
                 buf[bufIdx++] = andChar; // Write '&', then go to base64 mode.
                 inBase64 = true;
             }
             if (inBase64) {
                 base64Accum[base64AccumIdx++] = uChar >> 8;
                 base64Accum[base64AccumIdx++] = uChar & 0xFF;
 
                 if (base64AccumIdx == base64Accum.length) {
                     bufIdx += buf.write(base64Accum.toString('base64').replace(/\//g, ','), bufIdx);
                     base64AccumIdx = 0;
                 }
             }
         }
     }
 
     this.inBase64 = inBase64;
     this.base64AccumIdx = base64AccumIdx;
 
     return buf.slice(0, bufIdx);
 }
 
 Utf7IMAPEncoder.prototype.end = function() {
     var buf = Buffer.alloc(10), bufIdx = 0;
     if (this.inBase64) {
         if (this.base64AccumIdx > 0) {
             bufIdx += buf.write(this.base64Accum.slice(0, this.base64AccumIdx).toString('base64').replace(/\//g, ',').replace(/=+$/, ''), bufIdx);
             this.base64AccumIdx = 0;
         }
 
         buf[bufIdx++] = minusChar; // Write '-', then go to direct mode.
         this.inBase64 = false;
     }
 
     return buf.slice(0, bufIdx);
 }
 
 
 // -- Decoding
 
 function Utf7IMAPDecoder(options, codec) {
     this.iconv = codec.iconv;
     this.inBase64 = false;
     this.base64Accum = '';
 }
 
 var base64IMAPChars = base64Chars.slice();
 base64IMAPChars[','.charCodeAt(0)] = true;
 
 Utf7IMAPDecoder.prototype.write = function(buf) {
     var res = "", lastI = 0,
         inBase64 = this.inBase64,
         base64Accum = this.base64Accum;
 
     // The decoder is more involved as we must handle chunks in stream.
     // It is forgiving, closer to standard UTF-7 (for example, '-' is optional at the end).
 
     for (var i = 0; i < buf.length; i++) {
         if (!inBase64) { // We're in direct mode.
             // Write direct chars until '&'
             if (buf[i] == andChar) {
                 res += this.iconv.decode(buf.slice(lastI, i), "ascii"); // Write direct chars.
                 lastI = i+1;
                 inBase64 = true;
             }
         } else { // We decode base64.
             if (!base64IMAPChars[buf[i]]) { // Base64 ended.
                 if (i == lastI && buf[i] == minusChar) { // "&-" -> "&"
                     res += "&";
                 } else {
                     var b64str = base64Accum + buf.slice(lastI, i).toString().replace(/,/g, '/');
                     res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
                 }
 
                 if (buf[i] != minusChar) // Minus may be absorbed after base64.
                     i--;
 
                 lastI = i+1;
                 inBase64 = false;
                 base64Accum = '';
             }
         }
     }
 
     if (!inBase64) {
         res += this.iconv.decode(buf.slice(lastI), "ascii"); // Write direct chars.
     } else {
         var b64str = base64Accum + buf.slice(lastI).toString().replace(/,/g, '/');
 
         var canBeDecoded = b64str.length - (b64str.length % 8); // Minimal chunk: 2 quads -> 2x3 bytes -> 3 chars.
         base64Accum = b64str.slice(canBeDecoded); // The rest will be decoded in future.
         b64str = b64str.slice(0, canBeDecoded);
 
         res += this.iconv.decode(Buffer.from(b64str, 'base64'), "utf16-be");
     }
 
     this.inBase64 = inBase64;
     this.base64Accum = base64Accum;
 
     return res;
 }
 
 Utf7IMAPDecoder.prototype.end = function() {
     var res = "";
     if (this.inBase64 && this.base64Accum.length > 0)
         res = this.iconv.decode(Buffer.from(this.base64Accum, 'base64'), "utf16-be");
 
     this.inBase64 = false;
     this.base64Accum = '';
     return res;
 }