https://netpeak.ru/software/ga-openstat-code/

openstat-googleanalytics.js

var OpenStatParser={_params:{},_parsed:!1,_decode64:function(r){if("function"==typeof window.atob)return atob(r);var t,a,e,n,i,s,o,h,d="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",p=0,f=0,u="",c=[];if(!r)return r;r+="";do n=d.indexOf(r.charAt(p++)),i=d.indexOf(r.charAt(p++)),s=d.indexOf(r.charAt(p++)),o=d.indexOf(r.charAt(p++)),h=n<<18|i<<12|s<<6|o,t=h>>16&255,a=h>>8&255,e=255&h,64==s?c[f++]=String.fromCharCode(t):64==o?c[f++]=String.fromCharCode(t,a):c[f++]=String.fromCharCode(t,a,e);while(p<r.length);return u=c.join("")},_parse:function(){var r=window.location.search.substr(1),t=r.split("&");this._params={};for(var a=0;a<t.length;a++){var e=t[a].split("=");this._params[e[0]]=e[1]}this._parsed=!0},hasMarker:function(){return this._parsed||this._parse(),"undefined"!=typeof this._params._openstat},buildCampaignParams:function(){if(!this.hasMarker())return!1;var r=this._decode64(this._params._openstat),t=r.split(";");return{utmcampaign:t[1],utmsource:t[0],utmcontent:t[2]}}};

if (OpenStatParser.hasMarker()) {
  var campaignParams = OpenStatParser.buildCampaignParams();
  if (campaignParams !== false) {
    ga('set', {'campaignName': campaignParams.utmcampaign, 'campaignSource': campaignParams.utmsource, 'campaignMedium': 'cpc', 'campaignContent': campaignParams.utmcontent});
  }
}

openstatparser.js

var OpenStatParser = {
    _params: {},
    _parsed: false,
    _decode64: function(data) {
        if (typeof window['atob'] === 'function') {
            return atob(data);
        }

        var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
        var o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
            ac = 0,
            dec = "",
            tmp_arr = [];

        if (!data) {
            return data;
        }

        data += '';

        do {
            h1 = b64.indexOf(data.charAt(i++));
            h2 = b64.indexOf(data.charAt(i++));
            h3 = b64.indexOf(data.charAt(i++));
            h4 = b64.indexOf(data.charAt(i++));

            bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;

            o1 = bits >> 16 & 0xff;
            o2 = bits >> 8 & 0xff;
            o3 = bits & 0xff;

            if (h3 == 64) {
                tmp_arr[ac++] = String.fromCharCode(o1);
            } else if (h4 == 64) {
                tmp_arr[ac++] = String.fromCharCode(o1, o2);
            } else {
                tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
            }
        } while (i < data.length);

        dec = tmp_arr.join('');

        return dec;
    },
    _parse: function() {
        var prmstr = window.location.search.substr(1);
        var prmarr = prmstr.split('&');
        this._params = {};

        for (var i = 0; i < prmarr.length; i++) {
            var tmparr = prmarr[i].split('=');
            this._params[tmparr[0]] = tmparr[1];
        }

        this._parsed = true;
    },
    hasMarker: function() {
        if (!this._parsed) {
            this._parse();
        }
        return (typeof this._params['_openstat'] !== 'undefined') ? true : false;
    },
    buildCampaignParams: function() {
        if (!this.hasMarker()) {
            return false;
        }
        var openstat = this._decode64(this._params['_openstat']);
        var statarr = openstat.split(';');
        return {
          utmcampaign: statarr[1],
          utmsource: statarr[0],
          utmcontent: statarr[2]
        }
    }
}