var servicePointUserReader = ServicePointManager.FindServicePoint(new Uri("https://ipv4.gdt.qq.com/get_client_ip"));
    servicePointUserReader.BindIPEndPointDelegate = (sp, remote, retryCount) => new IPEndPoint(IPAddress.Parse("192.168.1.45"), 0);

static function OnBeforeRequest(oSession: Session) {

  if(oSession.url.Contains("114.cn"))
        {
            var strBody = oSession.GetRequestBodyAsString();
            
            
            strBody = strBody.Replace("a","b");
            oSession.utilSetRequestBody(strBody);
        } 

}


static function OnBeforeResponse(oSession: Session) {
        
        if(oSession.url.Contains("114.cn"))
        {
            var strBody =  oSession.GetResponseBodyAsString();
            strBody = strBody.Replace("a","b");
            oSession.utilSetResponseBody(strBody);
        }
    }