Warp+http/3=unable to record client ip?

Step of reproduce

  1. Use a browser with http/3 support (Firefox/90.0 for me)
  2. Enable CLoudflare Warp (I am using Warp+ on windows with version 1.5.461.0).
  3. Access https://www.cloudflare.com/cdn-cgi/trace (or any site behind cloudflare’s proxy)

Result

You will get (if luckily enough) answer like:

fl=4f432
h=www.cloudflare.com
ip=fd01:5ca1:ab1e:8a3a:e30:ea85:e086:bb09
ts=1627899291.735
visit_scheme=https
uag=Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0
colo=SJC
http=http/3
loc=XX
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off

Notice the fd01:5ca1:ab1e:8a3a:e30:ea85:e086:bb09, it is a local address, and loc=XX here.

Not only the address in trace, address recorded by my server (X-Forwarded-For) shows the local address too, making applications relay on per ip rate limit/user region no longer work.

(Might be some bugs present when the http/3 traffic routes between cloudflare servers?)

I think it’s a quirk with http3 and WARP, and i’m not sure if there’s an official response from Cloudflare regarding this, but it has been brought up before

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