email-dkim/lib/process-body.js

DomainKeys Identified Mail (DKIM)

/**
 * Canonicalize the message body according to
 * methods defined in RFC[XXXX]
 * @memberOf DKIM
 * @param {Buffer|String} message
 * @param {String} method - (simple|relaxed)
 * @throws {Error} If canonicalization method is unsupported
 * @return {String}
 */
function processBody(message, method) {

  method = method || 'simple'

  if (method !== 'simple' && method !== 'relaxed') {
    throw new Error('Canonicalization method "' + method + '" not supported')
  }

  // @see https://tools.ietf.org/html/rfc6376#section-3.4.3
  if (method === 'simple') {

    const msgLine = message.toString().split("\r\n")
    let removeCount = 0

    for (let l = msgLine.length - 1; l >= 0; l--) {
      if (msgLine[l] == '') {
        removeCount += 1
      } else {
        break
      }
    }
    for (let i = 0; i < removeCount; i++) {
      msgLine.pop()
    }

    return msgLine.join("\r\n") + "\r\n"
  }

  // @see https://tools.ietf.org/html/rfc6376#section-3.4.4
  if (method === 'relaxed') {
    return message.toString('binary')
      // Ignore all whitespace at the end of lines.
      .replace(/[\x20\x09]+(?=\r\n)/g, '')
      // Reduce all sequences of WSP within a line to a single SP
      .replace(/[\x20\x09]+/g, ' ')
      // Ignore all empty lines at the end of the message body.
      .replace(/(\r\n)+$/, '\r\n')
  }

}

module.exports = processBody