----- 内部域名如果http头中带有 X-YOHO-IP，则是PC/h5过来的请求，直接用这个作为real ip
----- 经过动态CDN,如果x-forward-for 只有1个IP地址，则取第一个;>=2个IP地址，例如 ip1,ip2,ip3,ip4， 则取倒数第二个，即ip3
----- 请求不经过动态CDN,取 x-forward-for 中最后一个IP地址，例如 ip1,ip2,ip3,ip4，取ip4

local realIp =  ngx.req.get_headers()["X-YOHO-IP"]
if realIp and (string.find(ngx.var.http_host,"yohoops%.org") or string.find(ngx.var.http_host,"yohops%.com"))  then
    return realIp
end


local xForwardFor =  ngx.var.http_x_forwarded_for;
if xForwardFor then
  local ips={}
  string.gsub(xForwardFor,'[^,]+',function(w) table.insert(ips, w) end )
  if string.find(ngx.var.http_host,"api%-dc",1) == 1 then
    if #ips >= 2 then
      realIp=ips[#ips-1]
    elseif #ips<=1 then
      realIp=ips[1]
    end
  else
   realIp=ips[#ips]
  end
end  

-- if not exist, then setup remote_addr
if realIp == nil then
  realIp = ngx.var.remote_addr;
end

return realIp;