"proxy_protocol": "v2" seems dosen't work for udp forward (from l4 to http)

[CharlesWou]

I wanna do udp forward (from l4 to http), and get real client ip by "proxy_protocol".
"proxy_proctocol_v2" has added UDP support , but it seems dosen't work despite I set "proxy_protocol" to "v2" in caddy.
Only "127.0.0.1" in log files, and I can't get real client ip.
Why? How to solve?

    "layer4": {
      "servers": {
        "fwd_udp": {
          "listen": [
            "udp/0.0.0.0:443"
          ],
          "routes": [
            {
              "handle": [
                {
                  "handler": "proxy",
                  "proxy_protocol": "v2",
                  "upstreams": [
                    {
                      "dial": [
                        "udp/127.0.0.1:7443"
                      ]
                    }
                  ]
                }
              ]
            }
          ]
        }
      }
    },
    "http": {
      "servers": {
         "srv_h3": {
            "listen": [
              "127.0.0.1:7443"
            ],
            "listener_wrappers": [
              {
                "wrapper": "proxy_protocol",
                "allow": [
                  "127.0.0.1/32"
                ]
              },
              {
                "wrapper": "tls"
              }
            ],
            ...........
         }
      }  
    }

[mohammed90]

This is duplicate of #269. It's a gap because l4 should wrap every UDP packet with the PROXY protocol header, while it currently only wraps the first packet.