wildduck/imap-core/lib/indexer/parse-mime-tree.js

330 lines
11 KiB
JavaScript

'use strict';
const addressparser = require('nodemailer/lib/addressparser');
/**
* Parses a RFC822 message into a structured object (JSON compatible)
*
* @constructor
* @param {String|Buffer} rfc822 Raw body of the message
*/
class MIMEParser {
constructor(rfc822) {
// ensure the input is a binary string
this.rfc822 = (rfc822 || '').toString('binary');
this._br = '';
this._pos = 0;
this.rawBody = '';
this.tree = {
rootNode: true,
childNodes: []
};
this._node = this.createNode(this.tree);
}
/**
* Parses the message, line by line
*/
parse() {
let line,
prevBr = '';
// keep parsing until the last linebreak is not a string (no linebreaks anymore)
while (typeof this._br === 'string') {
line = this.readLine();
switch (this._node.state) {
case 'header': // process header section
if (this.rawBody) {
this.rawBody += prevBr + line;
}
if (!line) {
this.processNodeHeader();
this.processContentType();
this._node.state = 'body';
} else {
this._node.header.push(line);
}
break;
case 'body': // process body section
this.rawBody += prevBr + line;
if (this._node.parentBoundary && (line === '--' + this._node.parentBoundary || line === '--' + this._node.parentBoundary + '--')) {
if (
this._node.parsedHeader['content-type'].value === 'message/rfc822' &&
(!this._node.parsedHeader['content-transfer-encoding'] ||
['7bit', '8bit', 'binary'].includes(this._node.parsedHeader['content-transfer-encoding']))
) {
this._node.message = parse(this._node.body.join(''));
}
if (line === '--' + this._node.parentBoundary) {
this._node = this.createNode(this._node.parentNode);
} else {
this._node = this._node.parentNode;
}
} else if (this._node.boundary && line === '--' + this._node.boundary) {
this._node = this.createNode(this._node);
} else {
// push the line with previous linebreak value
// if the array is joined together to a one string,
// then the linebreaks in the string are the 'original' ones
this._node.body.push((this._node.body.length ? prevBr : '') + line);
}
break;
default:
// never should be reached
throw new Error('Unexpected state');
}
// store the linebreak for later usage
prevBr = this._br;
}
}
/**
* Reads a line from the message body
*
* @return {String|Boolean} A line from the message
*/
readLine() {
let match = this.rfc822.substr(this._pos).match(/(.*?)(\r*\n|$)/);
if (match) {
this._br = match[2] || false;
this._pos += match[0].length;
return match[1];
}
return false;
}
/**
* Join body arrays into strings. Removes unnecessary fields
* from the tree (circular references prohibit conversion to JSON)
*/
finalizeTree() {
if (this._node.state === 'header') {
this.processNodeHeader();
this.processContentType();
}
if (this.tree.parsedHeader && this.tree.parsedHeader['content-type'].value === 'message/rfc822') {
this.tree.message = parse(this.tree.body.join(''));
}
let walker = node => {
if (node.body) {
if (node.parentNode === this.tree && node.parsedHeader['content-type'].value === 'message/rfc822') {
node.message = parse(node.body.join(''));
}
node.lineCount = node.body.length ? node.body.length - 1 : 0;
node.body = Buffer.from(
node.body
.join('')
// ensure proper line endings
.replace(/\r?\n/g, '\r\n'),
'binary'
);
node.size = node.body.length;
}
node.childNodes.forEach(walker);
// remove unneeded properties
delete node.parentNode;
delete node.state;
if (!node.childNodes.length) {
delete node.childNodes;
}
delete node.parentBoundary;
};
walker(this.tree);
}
/**
* Creates a new node with default values for the parse tree
*/
createNode(parentNode) {
let node = {
state: 'header',
childNodes: [],
header: [],
parsedHeader: {},
body: [],
multipart: false,
parentBoundary: parentNode.boundary,
boundary: false,
parentNode
};
parentNode.childNodes.push(node);
return node;
}
/**
* Processes header lines. Splits lines to key-value pairs
* and processes special values
*/
processNodeHeader() {
let key, value;
for (let i = this._node.header.length - 1; i >= 0; i--) {
if (i && this._node.header[i].match(/^\s/)) {
this._node.header[i - 1] = this._node.header[i - 1] + '\r\n' + this._node.header[i];
this._node.header.splice(i, 1);
} else {
value = this._node.header[i].split(':');
key = (value.shift() || '').trim().toLowerCase();
value = value.join(':').trim();
// Do not touch headers that have strange looking keys, keep these
// only in the unparsed array
if (/[^a-zA-Z0-9\-*]/.test(key) || key.length >= 100) {
continue;
}
// assume UTF-8 for binary headers
value = Buffer.from(value, 'binary').toString();
if (key in this._node.parsedHeader) {
if (Array.isArray(this._node.parsedHeader[key])) {
this._node.parsedHeader[key].unshift(value);
} else {
this._node.parsedHeader[key] = [value, this._node.parsedHeader[key]];
}
} else {
this._node.parsedHeader[key] = value.replace(/\s*\r?\n\s*/g, ' ');
}
}
}
// always ensure the presence of Content-Type
if (!this._node.parsedHeader['content-type']) {
this._node.parsedHeader['content-type'] = 'text/plain';
}
// parse additional params for Content-Type and Content-Disposition
['content-type', 'content-disposition'].forEach(key => {
if (this._node.parsedHeader[key]) {
this._node.parsedHeader[key] = this.parseValueParams([].concat(this._node.parsedHeader[key] || []).pop());
}
});
// ensure single value for selected fields
['content-transfer-encoding', 'content-id', 'content-description', 'content-language', 'content-md5', 'content-location'].forEach(key => {
if (Array.isArray(this._node.parsedHeader[key])) {
this._node.parsedHeader[key] = this._node.parsedHeader[key].pop();
}
});
// Parse address fields (join several fields with same key)
['from', 'sender', 'reply-to', 'to', 'cc', 'bcc'].forEach(key => {
let addresses = [];
if (this._node.parsedHeader[key]) {
[].concat(this._node.parsedHeader[key] || []).forEach(value => {
if (value) {
addresses = addresses.concat(addressparser(value) || []);
}
});
this._node.parsedHeader[key] = addresses;
}
});
}
/**
* Splits a value to an object.
* eg. 'text/plain; charset=utf-8' -> {value: 'text/plain', params:{charset: 'utf-8'}}
*
* @param {String} headerValue A string value for a header key
* @return {Object} Parsed value
*/
parseValueParams(headerValue) {
let data = {
value: '',
type: '',
subtype: '',
params: {}
};
let match;
let processEncodedWords = {};
(headerValue || '').split(';').forEach((part, i) => {
let key, value;
if (!i) {
data.value = part.trim();
data.subtype = data.value.split('/');
data.type = (data.subtype.shift() || '').toLowerCase();
data.subtype = data.subtype.join('/');
return;
}
value = part.split('=');
key = (value.shift() || '').trim().toLowerCase();
value = value.join('=').replace(/^['"\s]*|['"\s]*$/g, '');
// Do not touch headers that have strange looking keys, keep these
// only in the unparsed array
if (/[^a-zA-Z0-9\-*]/.test(key) || key.length >= 100) {
return;
}
// This regex allows for an optional trailing asterisk, for headers
// which are encoded with lang/charset info as well as a continuation.
// See https://tools.ietf.org/html/rfc2231 section 4.1.
if ((match = key.match(/^([^*]+)\*(\d)?\*?$/))) {
if (!processEncodedWords[match[1]]) {
processEncodedWords[match[1]] = [];
}
processEncodedWords[match[1]][Number(match[2]) || 0] = value;
} else {
data.params[key] = value;
}
data.hasParams = true;
});
// convert extended mime word into a regular one
Object.keys(processEncodedWords).forEach(key => {
let charset = '';
let value = '';
processEncodedWords[key].forEach(val => {
let parts = val.split("'"); // eslint-disable-line quotes
charset = charset || parts.shift();
value += (parts.pop() || '').replace(/%/g, '=');
});
data.params[key] = '=?' + (charset || 'ISO-8859-1').toUpperCase() + '?Q?' + value + '?=';
});
return data;
}
/**
* Checks Content-Type value for the current tree node.
*/
processContentType() {
if (!this._node.parsedHeader['content-type']) {
return;
}
if (this._node.parsedHeader['content-type'].type === 'multipart' && this._node.parsedHeader['content-type'].params.boundary) {
this._node.multipart = this._node.parsedHeader['content-type'].subtype;
this._node.boundary = this._node.parsedHeader['content-type'].params.boundary;
}
}
}
function parse(rfc822) {
let parser = new MIMEParser(rfc822);
let response;
parser.parse();
parser.finalizeTree();
response = parser.tree.childNodes[0] || false;
return response;
}
module.exports = parse;