sbc-inbound/lib/utils.js

const config = require('config');
let idx = 0;

function isWSS(req) {
  return req.getParsedHeader('Via')[0].protocol.toLowerCase().startsWith('ws');
}

function getAppserver() {
  const len = config.get('trunks.appserver').length;
  return config.get('trunks.appserver')[ idx++ % len];
}

function makeRtpEngineOpts(req, srcIsUsingSrtp, dstIsUsingSrtp) {
  const from = req.getParsedHeader('from');
  const common = {'call-id': req.get('Call-ID'), 'from-tag': from.params.tag};
  const rtpCharacteristics = config.get('transcoding.rtpCharacteristics');
  const srtpCharacteristics = config.get('transcoding.srtpCharacteristics');
  return {
    common,
    offer: Object.assign({'sdp': req.body, 'replace': ['origin', 'session-connection']}, common,
      dstIsUsingSrtp ? srtpCharacteristics : rtpCharacteristics),
    answer: Object.assign({}, common, srcIsUsingSrtp ? srtpCharacteristics : rtpCharacteristics)
  };
}

module.exports = {
  isWSS,
  getAppserver,
  makeRtpEngineOpts
};