Varnish redirection to Desktop

sub vcl_recv
{
  #no valid cookie, this is a first time user
  if(req.http.Cookie !~ "sitepref=m" && req.http.Cookie !~ "sitepref=www")
  {
    if(req.http.user-agent ~ "iPhone|Android" && req.http.host ~ "^www.beyondyoga.com")
    {
      error 841 "redirect m";
    }
    else if(req.http.user-agent !~ "iPhone|Android" && req.http.host ~ "^m.beyondyoga.com")
    {
      error 842 "redirect www";
    }
  }
  else if(req.http.Cookie ~ "sitepref=m" && req.http.host ~ "^www.beyondyoga.com")
  {
    error 841 "redirect m";
  }
  else if(req.http.Cookie ~ "sitepref=www" && req.http.host ~ "^m.beyondyoga.com")
  {
    error 842 "redirect www";
  }
}

sub vcl_fetch
{
  #set the cookie for future requests
  if(req.http.Cookie !~ "sitepref=m" && req.http.Cookie !~ "sitepref=w")
  {
    if(req.http.host ~ "^m.beyondyoga.com")
    {
      set beresp.http.Set-Cookie = "sitepref=m; Domain=beyondyoga.com; Path=/; Expires=Mon, 01 Jan 2024 12:00:00 GMT;";
    }
    else if(req.http.host ~ "^www.beyondyoga.com")
    {
      set beresp.http.Set-Cookie = "sitepref=www; Domain=beyondyoga.com; Path=/; Expires=Mon, 01 Jan 2024 12:00:00 GMT;";
    }
  }
}

sub vcl_error
{
  if(obj.status == 841)
  {
    #redirect to m.beyondyoga.com and set sitepref=m
    set obj.http.Location = "http://m.beyondyoga.com" + req.url;
    set obj.status = 301;
    set obj.http.Set-Cookie = "sitepref=m; Domain=beyondyoga.com; Path=/; Expires=Mon, 01 Jan 2024 12:00:00 GMT;";
    return(deliver);
  }
  else if(obj.status == 842)
  {
    #redirect to www.beyondyoga.com and set sitepref=www
    set obj.http.Location = "http://www.beyondyoga.com" + req.url;
    set obj.status = 301;
    set obj.http.Set-Cookie = "sitepref=www; Domain=beyondyoga.com; Path=/; Expires=Mon, 01 Jan 2024 12:00:00 GMT;";
    return(deliver);
  }
}