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628 lines
23 KiB
628 lines
23 KiB
/* eslint no-control-regex:0 */
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'use strict';
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const base64 = require('../base64');
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const qp = require('../qp');
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const mimeTypes = require('./mime-types');
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module.exports = {
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/**
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* Checks if a value is plaintext string (uses only printable 7bit chars)
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*
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* @param {String} value String to be tested
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* @returns {Boolean} true if it is a plaintext string
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*/
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isPlainText(value) {
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if (typeof value !== 'string' || /[\x00-\x08\x0b\x0c\x0e-\x1f\u0080-\uFFFF]/.test(value)) {
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return false;
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} else {
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return true;
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}
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},
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/**
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* Checks if a multi line string containes lines longer than the selected value.
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*
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* Useful when detecting if a mail message needs any processing at all –
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* if only plaintext characters are used and lines are short, then there is
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* no need to encode the values in any way. If the value is plaintext but has
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* longer lines then allowed, then use format=flowed
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*
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* @param {Number} lineLength Max line length to check for
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* @returns {Boolean} Returns true if there is at least one line longer than lineLength chars
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*/
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hasLongerLines(str, lineLength) {
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if (str.length > 128 * 1024) {
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// do not test strings longer than 128kB
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return true;
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}
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return new RegExp('^.{' + (lineLength + 1) + ',}', 'm').test(str);
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},
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/**
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* Encodes a string or an Buffer to an UTF-8 MIME Word (rfc2047)
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*
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* @param {String|Buffer} data String to be encoded
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* @param {String} mimeWordEncoding='Q' Encoding for the mime word, either Q or B
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* @param {Number} [maxLength=0] If set, split mime words into several chunks if needed
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* @return {String} Single or several mime words joined together
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*/
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encodeWord(data, mimeWordEncoding, maxLength) {
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mimeWordEncoding = (mimeWordEncoding || 'Q')
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.toString()
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.toUpperCase()
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.trim()
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.charAt(0);
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maxLength = maxLength || 0;
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let encodedStr;
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let toCharset = 'UTF-8';
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if (maxLength && maxLength > 7 + toCharset.length) {
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maxLength -= 7 + toCharset.length;
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}
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if (mimeWordEncoding === 'Q') {
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// https://tools.ietf.org/html/rfc2047#section-5 rule (3)
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encodedStr = qp.encode(data).replace(/[^a-z0-9!*+\-/=]/gi, chr => {
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let ord = chr
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.charCodeAt(0)
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.toString(16)
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.toUpperCase();
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if (chr === ' ') {
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return '_';
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} else {
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return '=' + (ord.length === 1 ? '0' + ord : ord);
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}
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});
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} else if (mimeWordEncoding === 'B') {
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encodedStr = typeof data === 'string' ? data : base64.encode(data);
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maxLength = maxLength ? Math.max(3, ((maxLength - (maxLength % 4)) / 4) * 3) : 0;
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}
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if (maxLength && (mimeWordEncoding !== 'B' ? encodedStr : base64.encode(data)).length > maxLength) {
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if (mimeWordEncoding === 'Q') {
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encodedStr = this.splitMimeEncodedString(encodedStr, maxLength).join('?= =?' + toCharset + '?' + mimeWordEncoding + '?');
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} else {
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// RFC2047 6.3 (2) states that encoded-word must include an integral number of characters, so no chopping unicode sequences
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let parts = [];
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let lpart = '';
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for (let i = 0, len = encodedStr.length; i < len; i++) {
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let chr = encodedStr.charAt(i);
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// check if we can add this character to the existing string
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// without breaking byte length limit
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if (Buffer.byteLength(lpart + chr) <= maxLength || i === 0) {
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lpart += chr;
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} else {
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// we hit the length limit, so push the existing string and start over
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parts.push(base64.encode(lpart));
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lpart = chr;
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}
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}
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if (lpart) {
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parts.push(base64.encode(lpart));
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}
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if (parts.length > 1) {
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encodedStr = parts.join('?= =?' + toCharset + '?' + mimeWordEncoding + '?');
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} else {
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encodedStr = parts.join('');
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}
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}
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} else if (mimeWordEncoding === 'B') {
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encodedStr = base64.encode(data);
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}
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return '=?' + toCharset + '?' + mimeWordEncoding + '?' + encodedStr + (encodedStr.substr(-2) === '?=' ? '' : '?=');
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},
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/**
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* Finds word sequences with non ascii text and converts these to mime words
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*
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* @param {String} value String to be encoded
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* @param {String} mimeWordEncoding='Q' Encoding for the mime word, either Q or B
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* @param {Number} [maxLength=0] If set, split mime words into several chunks if needed
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* @param {Boolean} [encodeAll=false] If true and the value needs encoding then encodes entire string, not just the smallest match
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* @return {String} String with possible mime words
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*/
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encodeWords(value, mimeWordEncoding, maxLength, encodeAll) {
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maxLength = maxLength || 0;
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let encodedValue;
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// find first word with a non-printable ascii in it
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let firstMatch = value.match(/(?:^|\s)([^\s]*[\u0080-\uFFFF])/);
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if (!firstMatch) {
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return value;
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}
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if (encodeAll) {
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// if it is requested to encode everything or the string contains something that resebles encoded word, then encode everything
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return this.encodeWord(value, mimeWordEncoding, maxLength);
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}
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// find the last word with a non-printable ascii in it
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let lastMatch = value.match(/([\u0080-\uFFFF][^\s]*)[^\u0080-\uFFFF]*$/);
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if (!lastMatch) {
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// should not happen
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return value;
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}
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let startIndex =
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firstMatch.index +
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(
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firstMatch[0].match(/[^\s]/) || {
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index: 0
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}
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).index;
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let endIndex = lastMatch.index + (lastMatch[1] || '').length;
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encodedValue =
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(startIndex ? value.substr(0, startIndex) : '') +
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this.encodeWord(value.substring(startIndex, endIndex), mimeWordEncoding || 'Q', maxLength) +
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(endIndex < value.length ? value.substr(endIndex) : '');
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return encodedValue;
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},
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/**
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* Joins parsed header value together as 'value; param1=value1; param2=value2'
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* PS: We are following RFC 822 for the list of special characters that we need to keep in quotes.
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* Refer: https://www.w3.org/Protocols/rfc1341/4_Content-Type.html
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* @param {Object} structured Parsed header value
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* @return {String} joined header value
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*/
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buildHeaderValue(structured) {
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let paramsArray = [];
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Object.keys(structured.params || {}).forEach(param => {
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// filename might include unicode characters so it is a special case
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// other values probably do not
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let value = structured.params[param];
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if (!this.isPlainText(value) || value.length >= 75) {
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this.buildHeaderParam(param, value, 50).forEach(encodedParam => {
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if (!/[\s"\\;:/=(),<>@[\]?]|^[-']|'$/.test(encodedParam.value) || encodedParam.key.substr(-1) === '*') {
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paramsArray.push(encodedParam.key + '=' + encodedParam.value);
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} else {
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paramsArray.push(encodedParam.key + '=' + JSON.stringify(encodedParam.value));
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}
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});
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} else if (/[\s'"\\;:/=(),<>@[\]?]|^-/.test(value)) {
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paramsArray.push(param + '=' + JSON.stringify(value));
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} else {
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paramsArray.push(param + '=' + value);
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}
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});
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return structured.value + (paramsArray.length ? '; ' + paramsArray.join('; ') : '');
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},
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/**
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* Encodes a string or an Buffer to an UTF-8 Parameter Value Continuation encoding (rfc2231)
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* Useful for splitting long parameter values.
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*
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* For example
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* title="unicode string"
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* becomes
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* title*0*=utf-8''unicode
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* title*1*=%20string
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*
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* @param {String|Buffer} data String to be encoded
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* @param {Number} [maxLength=50] Max length for generated chunks
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* @param {String} [fromCharset='UTF-8'] Source sharacter set
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* @return {Array} A list of encoded keys and headers
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*/
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buildHeaderParam(key, data, maxLength) {
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let list = [];
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let encodedStr = typeof data === 'string' ? data : (data || '').toString();
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let encodedStrArr;
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let chr, ord;
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let line;
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let startPos = 0;
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let i, len;
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maxLength = maxLength || 50;
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// process ascii only text
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if (this.isPlainText(data)) {
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// check if conversion is even needed
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if (encodedStr.length <= maxLength) {
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return [
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{
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key,
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value: encodedStr
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}
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];
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}
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encodedStr = encodedStr.replace(new RegExp('.{' + maxLength + '}', 'g'), str => {
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list.push({
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line: str
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});
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return '';
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});
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if (encodedStr) {
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list.push({
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line: encodedStr
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});
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}
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} else {
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if (/[\uD800-\uDBFF]/.test(encodedStr)) {
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// string containts surrogate pairs, so normalize it to an array of bytes
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encodedStrArr = [];
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for (i = 0, len = encodedStr.length; i < len; i++) {
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chr = encodedStr.charAt(i);
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ord = chr.charCodeAt(0);
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if (ord >= 0xd800 && ord <= 0xdbff && i < len - 1) {
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chr += encodedStr.charAt(i + 1);
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encodedStrArr.push(chr);
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i++;
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} else {
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encodedStrArr.push(chr);
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}
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}
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encodedStr = encodedStrArr;
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}
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// first line includes the charset and language info and needs to be encoded
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// even if it does not contain any unicode characters
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line = 'utf-8\x27\x27';
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let encoded = true;
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startPos = 0;
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// process text with unicode or special chars
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for (i = 0, len = encodedStr.length; i < len; i++) {
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chr = encodedStr[i];
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if (encoded) {
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chr = this.safeEncodeURIComponent(chr);
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} else {
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// try to urlencode current char
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chr = chr === ' ' ? chr : this.safeEncodeURIComponent(chr);
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// By default it is not required to encode a line, the need
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// only appears when the string contains unicode or special chars
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// in this case we start processing the line over and encode all chars
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if (chr !== encodedStr[i]) {
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// Check if it is even possible to add the encoded char to the line
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// If not, there is no reason to use this line, just push it to the list
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// and start a new line with the char that needs encoding
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if ((this.safeEncodeURIComponent(line) + chr).length >= maxLength) {
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list.push({
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line,
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encoded
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});
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line = '';
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startPos = i - 1;
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} else {
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encoded = true;
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i = startPos;
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line = '';
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continue;
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}
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}
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}
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// if the line is already too long, push it to the list and start a new one
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if ((line + chr).length >= maxLength) {
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list.push({
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line,
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encoded
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});
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line = chr = encodedStr[i] === ' ' ? ' ' : this.safeEncodeURIComponent(encodedStr[i]);
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if (chr === encodedStr[i]) {
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encoded = false;
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startPos = i - 1;
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} else {
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encoded = true;
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}
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} else {
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line += chr;
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}
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}
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if (line) {
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list.push({
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line,
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encoded
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});
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}
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}
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return list.map((item, i) => ({
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// encoded lines: {name}*{part}*
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// unencoded lines: {name}*{part}
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// if any line needs to be encoded then the first line (part==0) is always encoded
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key: key + '*' + i + (item.encoded ? '*' : ''),
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value: item.line
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}));
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},
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/**
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* Parses a header value with key=value arguments into a structured
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* object.
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*
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* parseHeaderValue('content-type: text/plain; CHARSET='UTF-8'') ->
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* {
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* 'value': 'text/plain',
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* 'params': {
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* 'charset': 'UTF-8'
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* }
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* }
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*
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* @param {String} str Header value
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* @return {Object} Header value as a parsed structure
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*/
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parseHeaderValue(str) {
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let response = {
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value: false,
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params: {}
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};
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let key = false;
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let value = '';
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let type = 'value';
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let quote = false;
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let escaped = false;
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let chr;
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for (let i = 0, len = str.length; i < len; i++) {
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chr = str.charAt(i);
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if (type === 'key') {
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if (chr === '=') {
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key = value.trim().toLowerCase();
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type = 'value';
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value = '';
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continue;
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}
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value += chr;
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} else {
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if (escaped) {
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value += chr;
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} else if (chr === '\\') {
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escaped = true;
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continue;
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} else if (quote && chr === quote) {
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quote = false;
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} else if (!quote && chr === '"') {
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quote = chr;
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} else if (!quote && chr === ';') {
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if (key === false) {
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response.value = value.trim();
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} else {
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response.params[key] = value.trim();
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}
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type = 'key';
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value = '';
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} else {
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value += chr;
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}
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escaped = false;
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}
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}
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if (type === 'value') {
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if (key === false) {
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response.value = value.trim();
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} else {
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response.params[key] = value.trim();
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}
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} else if (value.trim()) {
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response.params[value.trim().toLowerCase()] = '';
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}
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// handle parameter value continuations
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// https://tools.ietf.org/html/rfc2231#section-3
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// preprocess values
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Object.keys(response.params).forEach(key => {
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let actualKey, nr, match, value;
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if ((match = key.match(/(\*(\d+)|\*(\d+)\*|\*)$/))) {
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actualKey = key.substr(0, match.index);
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nr = Number(match[2] || match[3]) || 0;
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if (!response.params[actualKey] || typeof response.params[actualKey] !== 'object') {
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response.params[actualKey] = {
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charset: false,
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values: []
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};
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}
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value = response.params[key];
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if (nr === 0 && match[0].substr(-1) === '*' && (match = value.match(/^([^']*)'[^']*'(.*)$/))) {
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response.params[actualKey].charset = match[1] || 'iso-8859-1';
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value = match[2];
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}
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response.params[actualKey].values[nr] = value;
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// remove the old reference
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delete response.params[key];
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}
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});
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// concatenate split rfc2231 strings and convert encoded strings to mime encoded words
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Object.keys(response.params).forEach(key => {
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let value;
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if (response.params[key] && Array.isArray(response.params[key].values)) {
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value = response.params[key].values.map(val => val || '').join('');
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if (response.params[key].charset) {
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// convert "%AB" to "=?charset?Q?=AB?="
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response.params[key] =
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'=?' +
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response.params[key].charset +
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'?Q?' +
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value
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// fix invalidly encoded chars
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.replace(/[=?_\s]/g, s => {
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let c = s.charCodeAt(0).toString(16);
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if (s === ' ') {
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return '_';
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} else {
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return '%' + (c.length < 2 ? '0' : '') + c;
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}
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})
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// change from urlencoding to percent encoding
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.replace(/%/g, '=') +
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'?=';
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} else {
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response.params[key] = value;
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}
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}
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});
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return response;
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},
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/**
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* Returns file extension for a content type string. If no suitable extensions
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* are found, 'bin' is used as the default extension
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*
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* @param {String} mimeType Content type to be checked for
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* @return {String} File extension
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*/
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detectExtension: mimeType => mimeTypes.detectExtension(mimeType),
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/**
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* Returns content type for a file extension. If no suitable content types
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* are found, 'application/octet-stream' is used as the default content type
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*
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* @param {String} extension Extension to be checked for
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* @return {String} File extension
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*/
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detectMimeType: extension => mimeTypes.detectMimeType(extension),
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/**
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* Folds long lines, useful for folding header lines (afterSpace=false) and
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* flowed text (afterSpace=true)
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*
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* @param {String} str String to be folded
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* @param {Number} [lineLength=76] Maximum length of a line
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* @param {Boolean} afterSpace If true, leave a space in th end of a line
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* @return {String} String with folded lines
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*/
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foldLines(str, lineLength, afterSpace) {
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str = (str || '').toString();
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lineLength = lineLength || 76;
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let pos = 0,
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len = str.length,
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result = '',
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line,
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match;
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while (pos < len) {
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line = str.substr(pos, lineLength);
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if (line.length < lineLength) {
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result += line;
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break;
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}
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if ((match = line.match(/^[^\n\r]*(\r?\n|\r)/))) {
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line = match[0];
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result += line;
|
|
pos += line.length;
|
|
continue;
|
|
} else if ((match = line.match(/(\s+)[^\s]*$/)) && match[0].length - (afterSpace ? (match[1] || '').length : 0) < line.length) {
|
|
line = line.substr(0, line.length - (match[0].length - (afterSpace ? (match[1] || '').length : 0)));
|
|
} else if ((match = str.substr(pos + line.length).match(/^[^\s]+(\s*)/))) {
|
|
line = line + match[0].substr(0, match[0].length - (!afterSpace ? (match[1] || '').length : 0));
|
|
}
|
|
|
|
result += line;
|
|
pos += line.length;
|
|
if (pos < len) {
|
|
result += '\r\n';
|
|
}
|
|
}
|
|
|
|
return result;
|
|
},
|
|
|
|
/**
|
|
* Splits a mime encoded string. Needed for dividing mime words into smaller chunks
|
|
*
|
|
* @param {String} str Mime encoded string to be split up
|
|
* @param {Number} maxlen Maximum length of characters for one part (minimum 12)
|
|
* @return {Array} Split string
|
|
*/
|
|
splitMimeEncodedString: (str, maxlen) => {
|
|
let curLine,
|
|
match,
|
|
chr,
|
|
done,
|
|
lines = [];
|
|
|
|
// require at least 12 symbols to fit possible 4 octet UTF-8 sequences
|
|
maxlen = Math.max(maxlen || 0, 12);
|
|
|
|
while (str.length) {
|
|
curLine = str.substr(0, maxlen);
|
|
|
|
// move incomplete escaped char back to main
|
|
if ((match = curLine.match(/[=][0-9A-F]?$/i))) {
|
|
curLine = curLine.substr(0, match.index);
|
|
}
|
|
|
|
done = false;
|
|
while (!done) {
|
|
done = true;
|
|
// check if not middle of a unicode char sequence
|
|
if ((match = str.substr(curLine.length).match(/^[=]([0-9A-F]{2})/i))) {
|
|
chr = parseInt(match[1], 16);
|
|
// invalid sequence, move one char back anc recheck
|
|
if (chr < 0xc2 && chr > 0x7f) {
|
|
curLine = curLine.substr(0, curLine.length - 3);
|
|
done = false;
|
|
}
|
|
}
|
|
}
|
|
|
|
if (curLine.length) {
|
|
lines.push(curLine);
|
|
}
|
|
str = str.substr(curLine.length);
|
|
}
|
|
|
|
return lines;
|
|
},
|
|
|
|
encodeURICharComponent: chr => {
|
|
let res = '';
|
|
let ord = chr
|
|
.charCodeAt(0)
|
|
.toString(16)
|
|
.toUpperCase();
|
|
|
|
if (ord.length % 2) {
|
|
ord = '0' + ord;
|
|
}
|
|
|
|
if (ord.length > 2) {
|
|
for (let i = 0, len = ord.length / 2; i < len; i++) {
|
|
res += '%' + ord.substr(i, 2);
|
|
}
|
|
} else {
|
|
res += '%' + ord;
|
|
}
|
|
|
|
return res;
|
|
},
|
|
|
|
safeEncodeURIComponent(str) {
|
|
str = (str || '').toString();
|
|
|
|
try {
|
|
// might throw if we try to encode invalid sequences, eg. partial emoji
|
|
str = encodeURIComponent(str);
|
|
} catch (E) {
|
|
// should never run
|
|
return str.replace(/[^\x00-\x1F *'()<>@,;:\\"[\]?=\u007F-\uFFFF]+/g, '');
|
|
}
|
|
|
|
// ensure chars that are not handled by encodeURICompent are converted as well
|
|
return str.replace(/[\x00-\x1F *'()<>@,;:\\"[\]?=\u007F-\uFFFF]/g, chr => this.encodeURICharComponent(chr));
|
|
}
|
|
};
|
|
|