candidate.js

var debug = require('cog/logger')('rtc-validator');
var rePrefix = /^(?:a=)?candidate:/;

/*

validation rules as per:
http://tools.ietf.org/html/draft-ietf-mmusic-ice-sip-sdp-03#section-8.1

   candidate-attribute   = "candidate" ":" foundation SP component-id SP
                           transport SP
                           priority SP
                           connection-address SP     ;from RFC 4566
                           port         ;port from RFC 4566
                           SP cand-type
                           [SP rel-addr]
                           [SP rel-port]
                           *(SP extension-att-name SP
                                extension-att-value)

   foundation            = 1*32ice-char
   component-id          = 1*5DIGIT
   transport             = "UDP" / transport-extension
   transport-extension   = token              ; from RFC 3261
   priority              = 1*10DIGIT
   cand-type             = "typ" SP candidate-types
   candidate-types       = "host" / "srflx" / "prflx" / "relay" / token
   rel-addr              = "raddr" SP connection-address
   rel-port              = "rport" SP port
   extension-att-name    = token
   extension-att-value   = *VCHAR
   ice-char              = ALPHA / DIGIT / "+" / "/"
*/
var partValidation = [
  [ /.+/, 'invalid foundation component', 'foundation' ],
  [ /\d+/, 'invalid component id', 'component-id' ],
  [ /(UDP|TCP)/i, 'transport must be TCP or UDP', 'transport' ],
  [ /\d+/, 'numeric priority expected', 'priority' ],
  [ new RegExp(require('reu/ip').source + '|.*\.local$'), 'invalid connection address', 'connection-address' ],
  [ /\d+/, 'invalid connection port', 'connection-port' ],
  [ /typ/, 'Expected "typ" identifier', 'type classifier' ],
  [ /.+/, 'Invalid candidate type specified', 'candidate-type' ]
];

/**
  ### `rtc-validator/candidate`

  Validate that an `RTCIceCandidate` (or plain old object with data, sdpMid,
  etc attributes) is a valid ice candidate.

  Specs reviewed as part of the validation implementation:

  - <http://tools.ietf.org/html/draft-ietf-mmusic-ice-sip-sdp-03#section-8.1>
  - <http://tools.ietf.org/html/rfc5245>

**/
module.exports = function(data) {
  var errors = [];
  var candidate = data && (data.candidate || data);
  var prefixMatch = candidate && rePrefix.exec(candidate);
  var parts = prefixMatch && candidate.slice(prefixMatch[0].length).split(/\s/);

  if (! candidate) {
    return [ new Error('empty candidate') ];
  }

  // check that the prefix matches expected
  if (! prefixMatch) {
    return [ new Error('candidate did not match expected sdp line format') ];
  }

  // perform the part validation
  errors = errors.concat(parts.map(validateParts)).filter(Boolean);

  return errors;
};

function validateParts(part, idx) {
  var validator = partValidation[idx];

  if (validator && (! validator[0].test(part))) {
    debug(validator[2] + ' part failed validation: ' + part);
    return new Error(validator[1]);
  }
}