# Websocket proxying module questions **URL:** \ **Category:** NGINX\ **Created:** [November 19, 2010, 1:33pm UTC](https://www.ruby-forum.com/t/websocket-proxying-module-questions/199360 "2010-11-19T13:33:37Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![okkezSS](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/o/85f322/32.png) [@okkezSS](https://www.ruby-forum.com/u/okkezSS)\ **Post date:** [November 19, 2010, 1:33pm UTC](https://www.ruby-forum.com/t/websocket-proxying-module-questions/199360/1 "2010-11-19T13:33:37Z")
Hello, I’m wondering if it’s possible to make a module for proxying websockets for nginx. I read [Emiller’s Guide to Nginx Module Development – Evan Miller](http://www.evanmiller.org/nginx-modules-guide.html#proxying) … > From what I understand nginx normally works like this: 1. keep connection with client 2. connect to proxy and make request 3. do something else 4. get response from proxy and reply to client Now, a websocket connection will drop when it issues the upgrade command to nginx. A couple of questions 1. Does nginx need a persistent connection per client with the proxy to do websocket proxying? 2. For proper websocket proxying would the proxy rather have to be a gateway or tunneling proxy in nature? 3. If 2 holds, does that even fit into the nginx architecture? I know there is handshake issues with draft 76, but assuming I ignore them, is it possible to implement a websocket proxy to nginx? If so, can anyone give me some hints on how to do that? If not what would be the alternative? If I were to build a websocket module for nginx, that does all the handshaking inside nginx, how would the backend notify nginx that there’s new data available? Regards, Reza Posted at Nginx Forum: > **[websocket proxying module questions](https://forum.nginx.org/read.php?2,151908,151908#msg-151908)** > > Hello, I'm wondering if it's possible to make a module for proxying websockets for nginx. I read http://www.evanmiller.org/nginx-modules-guide.html#proxying ... From what I understand nginx normally works like this: 1. keep connection with client ---
**Author:** ![rezajelveh](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/45deac/32.png) [@rezajelveh](https://www.ruby-forum.com/u/rezajelveh)\ **Post date:** [November 20, 2010, 5:14pm UTC](https://www.ruby-forum.com/t/websocket-proxying-module-questions/199360/2 "2010-11-20T17:14:56Z")
ok another update.~m~16~m~5890598851256073…~m~16~m~~j~{“buffer”:[]}. doesn’t belong in the handshake response. it’s actually websocket framing. the [socket.io](http://socket.io) server will respond not only with the handshake response but immediately throw a session id back at nginx. since nginx doesn’t know anything about websocket framing, it will think that it belongs to the challenge response and mess it up. any suggestions on how to switch from http to websocket framing? Posted at Nginx Forum: > **[Re: websocket proxying module questions](https://forum.nginx.org/read.php?2,151908,152070#msg-152070)** > > Hello, I'm wondering if it's possible to make a module for proxying websockets for nginx. I read http://www.evanmiller.org/nginx-modules-guide.html#proxying ... From what I understand nginx normally works like this: 1. keep connection with client ---
**Author:** ![rezajelveh](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/45deac/32.png) [@rezajelveh](https://www.ruby-forum.com/u/rezajelveh)\ **Post date:** [November 20, 2010, 4:29pm UTC](https://www.ruby-forum.com/t/websocket-proxying-module-questions/199360/3 "2010-11-20T16:29:08Z")
ok little update. first problem is obviously the missing 8 byte of the handshake. what happens is the following: clients sends handshake GET /socket.io/websocket HTTP/1.1 Upgrade: WebSocket Connection: Upgrade Host: websocket.local Origin: [http://websocket.local](http://websocket.local) Sec-WebSocket-Key1: '6F24 \>168D1m/2T7b Sec-WebSocket-Key2: 3 84w6 5 u{U45 7 17 Cookie: socketio=websocket 12345678 the server would forward the following: GET /socket.io/websocket HTTP/1.0 Host: websocket.local X-Real-IP: 127.0.0.1 X-Forwarded-For: 127.0.0.1 Connection: close Upgrade: WebSocket Origin: [http://websocket.local](http://websocket.local) Sec-WebSocket-Key1: '6F24 \>168D1m/2T7b Sec-WebSocket-Key2: 3 84w6 5 u{U45 7 17 Cookie: socketio=websocket note the missing websocket key3. This is easily worked around(fixed) by adding ``` if (ngx_strcasestrn(h->key.data, "upgrade", 7 - 1) && ngx_strcasestrn(h->value.data, "websocket", 9 - 1)) { r->headers_in.content_length_n = 8; ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ``` r-\>connection-\>log, 0, “Upgrade header found”); } to ngx\_http\_request.c:ngx\_http\_process\_request\_headers the next thing i don’t get, node will response with a handshake: HTTP/1.1 101 WebSocket Protocol Handshake Upgrade: WebSocket Connection: Upgrade Sec-WebSocket-Origin: [http://websocket.local](http://websocket.local) Sec-WebSocket-Location: ws://websocket.local/socket.io/websocket n.E…Q.}…/.(s.~m~16~m~5890598851256073…~m~16~m~~j~{“buffer”:[]}. nginx will return the following: HTTP/1.1 101 WebSocket Protocol Handshake Server: nginx/0.7.67 Date: Fri, 19 Nov 2010 13:41:48 GMT Transfer-Encoding: chunked Connection: keep-alive Upgrade: WebSocket Sec-WebSocket-Origin: [http://websocket.local](http://websocket.local) Sec-WebSocket-Location: ws://websocket.local/socket.io/websocket 44 n.E…Q.}…/.(s.~m~16~m~5890598851256073…~m~16~m~~j~{“buffer”:[]}. Question: 1. where do the 44 come in? how do they fit in? 2. can i store the state of the connection as being a websocket now. so that it doesn’t rewrite the connection header? Regards, Reza Posted at Nginx Forum: > **[Re: websocket proxying module questions](https://forum.nginx.org/read.php?2,151908,152064#msg-152064)** > > Hello, I'm wondering if it's possible to make a module for proxying websockets for nginx. I read http://www.evanmiller.org/nginx-modules-guide.html#proxying ... From what I understand nginx normally works like this: 1. keep connection with client ---
**Author:** ![rezajelveh](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/45deac/32.png) [@rezajelveh](https://www.ruby-forum.com/u/rezajelveh)\ **Post date:** [November 21, 2010, 4:17pm UTC](https://www.ruby-forum.com/t/websocket-proxying-module-questions/199360/4 "2010-11-21T16:17:53Z")
another quick update, adding a content-length: 16 header in my [socket.io](http://socket.io) instance(note that’s not part of the websocket draft). nginx will forward the handshake response properly. and chrome and safari will establish a websocket connection which works only server → client. i explained it a bit more detailed in irc 14:02 [timebomb] no 14:02 [timebomb] server to client 14:02 [timebomb] there’s 2 problems 14:03 [timebomb] no.1 when you make a high timeout proxy connection, nginx will assume the websocket frames are just the rest of the previous html response. so it will keep forwarding the websocket requests from the server back to the client 14:03 [timebomb] however the frontend side isn’t able to send data back over that same connection 14:04 [timebomb] no.2 once the websocket connection is established the framing is something like 00 data ff 14:04 [timebomb] it will look like this: 14:04 [timebomb] 127.0.0.1 - - [21/Nov/2010:13:28:27 +0100] “GET /socket.io/websocket HTTP/1.1” 101 589 “-” “-” 14:04 [timebomb] 127.0.0.1 - - [21/Nov/2010:13:28:27 +0100] “\x00~m~4~m~~h~1#” 400 173 “-” “-” 14:04 [timebomb] nginx will return a 400 bad request answer 14:05 [timebomb] the best solution i can think of right now is to wrap that request in a html get at frontend side and then unwrap it internally at the proxy side 14:07 [timebomb] also i needed to add a content-length: 16 header to my node.js handshake response and a content-length: 8Â internally in nginx for the handshake request otherwise nginx would drop the websocket key 3 14:08 [Evet] things getting more complicated 14:09 \*\*\* netzsportler [~removed\_email\_address@domain.invalid] has quit [Ping timeout: 245 seconds] 14:09 [timebomb] about that wrap and unwrapping … it would be easily avoided if there was a way to avoid the html filter chain once the connection is established 14:09 [timebomb] i just don’t know how and if that’s possible Posted at Nginx Forum: > **[Re: websocket proxying module questions](https://forum.nginx.org/read.php?2,151908,152227#msg-152227)** > > Hello, I'm wondering if it's possible to make a module for proxying websockets for nginx. I read http://www.evanmiller.org/nginx-modules-guide.html#proxying ... From what I understand nginx normally works like this: 1. keep connection with client