digest.js

// The MIT License
// 
// Copyright (c) 2012 Tim Smart
// 
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files
// (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software, and
// to permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
// 
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

var uuid  = require('node-uuid').v4
var hash  = require('crypto').createHash

/**
 * Parse a comma seperated list header
 *
 * @param {String} header
 * @return {Object}
 */
function parseListHeader (header) {
  var char              = ''
  var buf               = []
  var s                 = {}
  var out               = {}

  for (var i = 0, il = header.length; i < il; i++) {
    char                = header[i]

    if (!s.gotval) {
      buf.push(char)
    }

    if (!s.gotkey && '=' === char) {
      buf.pop()
      s.gotkey          = buf.join('').trim()
      buf               = []

    } else if (s.gotkey) {
      if (!s.gotdelim && buf.length === 1 && ('"' === char || "'" === char)) {
        s.gotdelim      = char

      } else if (!s.gotdelim && ',' === char) {
        buf.pop()
        out[s.gotkey]   = buf.join('')
        buf             = []
        s               = {}

      } else if (s.gotdelim) {
        if ('\\' === char && s.gotdelim === header[i + 1]) {
          buf.pop()
          if ("'" === s.gotdelim) {
            buf.push('"')
          } else {
            buf.push('"')
          }
          ;++i

        } else if (s.gotdelim === char) {
          if ("'" === char) {
            buf.pop()
            buf.push('"')
          }
          out[s.gotkey] = JSON.parse(buf.join(''))
          buf           = []
          s.gotval      = true

        } else if (s.gotval && ',' === char) {
          s             = {}
        }
      }
    }
  }

  return out
}

/**
 * Stringify a object into a list header
 *
 * @param {Object} obj
 * @return {String}
 */
function stringifyListHeader (obj) {
  var keys  = Object.keys(obj)
  var key   = ''
  var buf   = []

  for (var i = 0, il = keys.length; i < il; i++) {
    key     = keys[i]
    buf.push(
      [ key
      , JSON.stringify(obj[key])
      ]
      .join('=')
    )
  }

  return buf.join(', ')
}

var nccount = 0

// Export
exports.createHeader =
function createHeader (uri, header, username, password) {
  var details   = parseListHeader(header.slice(7)) // Remove 'Digest '
  if (!details) return null

  ;++nccount
  var cnonce    = uuid().replace(/-/g, '')
  var digest    =
    { username  : username
    , realm     : details.realm
    , opaque    : details.opaque
    , nonce     : details.nonce
    , cnonce    : cnonce
    , nc        : nccount
    , uri       : uri
    , qop       : 'auth'
    }

  var ha1       = hash('md5')
    .update(
      [ digest.username
      , digest.realm
      , password
      ]
      .join(':')
    )
    .digest('hex')
  var ha2       = hash('md5')
    .update(
      [ 'GET'
      , digest.uri
      ]
      .join(':')
    )
    .digest('hex')
  digest.response  = hash('md5')
    .update(
      [ ha1
      , digest.nonce
      , digest.nc
      , digest.cnonce
      , 'auth'
      , ha2
      ]
      .join(':')
    )
    .digest('hex')

  return 'Digest ' + stringifyListHeader(digest)
}