send-mail/node_modules/nodemailer/lib/dkim/sign.js

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2020-03-01 05:01:03 +07:00
'use strict';
const punycode = require('punycode');
const mimeFuncs = require('../mime-funcs');
const crypto = require('crypto');
/**
* Returns DKIM signature header line
*
* @param {Object} headers Parsed headers object from MessageParser
* @param {String} bodyHash Base64 encoded hash of the message
* @param {Object} options DKIM options
* @param {String} options.domainName Domain name to be signed for
* @param {String} options.keySelector DKIM key selector to use
* @param {String} options.privateKey DKIM private key to use
* @return {String} Complete header line
*/
module.exports = (headers, hashAlgo, bodyHash, options) => {
options = options || {};
// all listed fields from RFC4871 #5.5
let defaultFieldNames =
'From:Sender:Reply-To:Subject:Date:Message-ID:To:' +
'Cc:MIME-Version:Content-Type:Content-Transfer-Encoding:Content-ID:' +
'Content-Description:Resent-Date:Resent-From:Resent-Sender:' +
'Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:' +
'List-Id:List-Help:List-Unsubscribe:List-Subscribe:List-Post:' +
'List-Owner:List-Archive';
let fieldNames = options.headerFieldNames || defaultFieldNames;
let canonicalizedHeaderData = relaxedHeaders(headers, fieldNames, options.skipFields);
let dkimHeader = generateDKIMHeader(options.domainName, options.keySelector, canonicalizedHeaderData.fieldNames, hashAlgo, bodyHash);
let signer, signature;
canonicalizedHeaderData.headers += 'dkim-signature:' + relaxedHeaderLine(dkimHeader);
signer = crypto.createSign(('rsa-' + hashAlgo).toUpperCase());
signer.update(canonicalizedHeaderData.headers);
try {
signature = signer.sign(options.privateKey, 'base64');
} catch (E) {
return false;
}
return dkimHeader + signature.replace(/(^.{73}|.{75}(?!\r?\n|\r))/g, '$&\r\n ').trim();
};
module.exports.relaxedHeaders = relaxedHeaders;
function generateDKIMHeader(domainName, keySelector, fieldNames, hashAlgo, bodyHash) {
let dkim = [
'v=1',
'a=rsa-' + hashAlgo,
'c=relaxed/relaxed',
'd=' + punycode.toASCII(domainName),
'q=dns/txt',
's=' + keySelector,
'bh=' + bodyHash,
'h=' + fieldNames
].join('; ');
return mimeFuncs.foldLines('DKIM-Signature: ' + dkim, 76) + ';\r\n b=';
}
function relaxedHeaders(headers, fieldNames, skipFields) {
let includedFields = new Set();
let skip = new Set();
let headerFields = new Map();
(skipFields || '')
.toLowerCase()
.split(':')
.forEach(field => {
skip.add(field.trim());
});
(fieldNames || '')
.toLowerCase()
.split(':')
.filter(field => !skip.has(field.trim()))
.forEach(field => {
includedFields.add(field.trim());
});
for (let i = headers.length - 1; i >= 0; i--) {
let line = headers[i];
// only include the first value from bottom to top
if (includedFields.has(line.key) && !headerFields.has(line.key)) {
headerFields.set(line.key, relaxedHeaderLine(line.line));
}
}
let headersList = [];
let fields = [];
includedFields.forEach(field => {
if (headerFields.has(field)) {
fields.push(field);
headersList.push(field + ':' + headerFields.get(field));
}
});
return {
headers: headersList.join('\r\n') + '\r\n',
fieldNames: fields.join(':')
};
}
function relaxedHeaderLine(line) {
return line
.substr(line.indexOf(':') + 1)
.replace(/\r?\n/g, '')
.replace(/\s+/g, ' ')
.trim();
}