docker-proxy & IPv6: weird errors in the log

[JanKoppe]

I'm seeing some weird issue, not sure if this is the fault of Docker or the SRT lib. When running a container with port forwarding on Docker 20.10.8, I'm seeing some weird errors in the logs for IPv6 connections. IPv4 (the first connection in the log) actually works great, and even sees the true client IP. When connecting with IPv6, apparently, the SRT lib falls on its nose while decoding the Client IP. It then falls back to the internal gateway IP of the Docker network. This seems only cosmetic - the data still arrives fine.

Logs:

srtrelay_1  | 2021/09/11 07:55:17 Read config from config.toml
srtrelay_1  | 2021/09/11 07:55:17 SRT Listening on :::20000
srtrelay_1  | 2021/09/11 07:55:17 API listening on :8080
srtrelay_1  | 2021/09/11 07:55:33 213.240.**.**:36586 - publish foo
srtrelay_1  | 2021/09/11 07:58:22 213.240.**.**:36586 - foo - The socket has been closed
srtrelay_1  | 2021/09/11 07:58:22 Removing stream foo
srtrelay_1  | 08:00:20.088221/SRT:RcvQ:w1*E:SRT.in: pton: IPE or net error: can't determine IPv4 carryover format: 12a:f804:**:**:0:0:0:200
srtrelay_1  | 08:00:20.088637/SRT:RcvQ:w1*E:SRT.in: pton: IPE or net error: can't determine IPv4 carryover format: 12a:f804:**:**:0:0:0:200
srtrelay_1  | 2021/09/11 08:00:20 172.20.0.1:50787 - publish foo
srtrelay_1  | 2021/09/11 08:01:51 172.20.0.1:50787 - foo - The socket has been closed

docker-compose.yaml:

version: '3.8'

services:
  srtrelay:
    image: ghcr.io/voc/srtrelay/srtrelay:latest
    volumes:
      - ./srtrelay.toml:/home/srtrelay/config.toml:ro
    ports:
      - 20000:20000/udp

# ss -ulpn
State   Recv-Q  Send-Q   Local Address:Port    Peer Address:Port  Process
UNCONN  0       0              0.0.0.0:20000        0.0.0.0:*      users:(("docker-proxy",pid=338418,fd=4))
UNCONN  0       0                 [::]:20000           [::]:*      users:(("docker-proxy",pid=338425,fd=4))