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Proxying Websockets and QLC
Posted: Wed Feb 17, 2021 5:56 pm
by sandinak
Heya, So this is an interesting one. I am trying to allow my students to control a lab I have setup in the shop. To do this I have created a website on a virtually hosted machine that has a VPN back here to the shop and a running version of QLC. ( hidden behind a local BasicAuth ).
Using Apache httpd and config is thus:
Code: Select all
RewriteEngine on
RewriteCond ${HTTP:Upgrade} websocket [NC]
RewriteCond ${HTTP:Connection} upgrade [NC]
RewriteRule .* "wss:/192.168.1.15:9999/$1" [P,L]
ProxyPass /qlcplusWS ws://192.168.1.15:9999/qlcplusWS retry=4
ProxyPassReverse /qlcplusWS ws://192.168.1.15:9999/qlcplusWS retry=4
# everything else
ProxyPass / http://192.168.1.15:9999/
ProxyPassReverse / http://192.168.1.15:9999/
So doing some testing and getting some interesting results:
- at first startup of httpd... first client to connect wins and can run things.
- local clients using the local address work just fine .. they can initiate control and it's reflected both places
- second and subsequent remote client connects, no error but can't do anything except see the page. No change reflected.
- subsequent local clients work just fine and do the Right thing(tm)
I am kinda sure this is apache having to deal with multiple source clients and the proxy not doing the right thing .. but was curious if anyone else has figured this one out before i go tcpdumpster diving and/or use the source luke.
Re: Proxying Websockets and QLC
Posted: Thu Feb 25, 2021 8:27 am
by Sp4rKy
Hi,
more used to nginx than apache but:
* it seems you're missing a / in rewriterule (wss://)
* you have a mix of ws and wss, afaik qlc+ only uses insecure (ws)
*I *think* you have a mix of config between rewriterule and proxypass : your rewrite rule matchs everything
Can you try something like :
Code: Select all
ProxyPass / http://192.168.1.15:9999/
RewriteEngine on
RewriteCond ${HTTP:Upgrade} websocket [NC]
RewriteCond ${HTTP:Connection} upgrade [NC]
RewriteRule ^/qlcplusWS.* "ws://192.168.1.15:9999/$1" [P,L]
?
Re: Proxying Websockets and QLC
Posted: Thu Feb 25, 2021 2:31 pm
by sandinak
Good finds! I adjusted things and I think I found the culprit
Code: Select all
x.x.x.x - - [25/Feb/2021:14:01:09 +0000] "GET /qlcplusWS HTTP/1.1" [b]401[/b] 381 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Safari/605.1.15"
The second connection is getting a 401 .. and a different Sec-WebSocket-Key on the connection. did some quick research and looks like this may be a common problem for multiple clients in QT. Gonna try with the built-in HTTP auth once I write a tool for creating/managing the password file from the C/L
