rewrite_xff

gistfile1.txt

header_filter_by_lua_block {                                                                                            
    function get_xff(s, delimiter)
        result = {};
        for match in (s..delimiter):gmatch("(.-)"..delimiter) do
            table.insert(result, match);
        end
        return result[#result];
    end

    xff = ngx.req.get_headers()["X-Forwarded-For"]
    ngx.req.clear_header("X-Forwarded-For")
    new_xff = get_xff(xff, ",")
    ngx.req.set_header("X-Forwarded-For", new_xff)
}

header_filter_by_lua_block {                                                                                                                                                                                       
  local xff = ngx.req.get_headers()["X-Forwarded-For"]                                                                                                                                                             
  ngx.req.clear_header("X-Forwarded-For")                                                                                                                                                                          
  local new_xff = string.match(xff, ",? *([^,]+)$")`                                                                                                                                                               
  ngx.req.set_header("X-Forwarded-For", new_xff)                                                                                                                                                                   
}