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HACK: add support for using a proxy for wss connections #74

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HACK: add support for using a proxy for wss connections #74

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17 changes: 15 additions & 2 deletions websocket.el
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Original file line number Diff line number Diff line change
Expand Up @@ -693,14 +693,27 @@ to the websocket protocol.
(port (if (= 0 (url-port url-struct))
(if (eq type 'tls) 443 80)
(url-port url-struct)))
(host (url-host url-struct)))
(host (url-host url-struct))
(url-as-http (let ((url-as-http (copy-sequence url-struct)))
(setf (url-type url-as-http) (if (eq type 'plain) "http" "https"))
url-as-http))
(proxy (url-generic-parse-url (url-find-proxy-for-url url-as-http (url-host url-as-http)))))
(if (eq type 'plain)
(make-network-process :name name :buffer nil :host host
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@ahyatt ahyatt Sep 5, 2020

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Will this work with http proxies? I'd guess you would need to make the host different if it is a proxy?

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@catern catern Sep 5, 2020

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I'm not sure what you mean by "http proxies" - the code I have here only works with proxies that talk plain HTTP without encryption. (The gnutls-negotiate later on is for TLS with the websocket server)

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@ahyatt ahyatt Sep 8, 2020

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Sorry, I wrote something that didn't make sense.

The way I read this, it doesn't look like it would go through a proxy for unencrypted websockets. The logic testing for proxies is only execute if type is not 'plain.

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@catern catern Sep 8, 2020

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Right, this only works for wss:// at the moment. I didn't have a need for ws:// and didn't set up a testing environment for it. In theory it could be as simple as not doing the gnutls-negotiate.

:service port :nowait nowait)
(if proxy
(let ((plain-conn (make-network-process
:name name :buffer nil :host (url-host proxy)
:service (url-port proxy))))
(let ((url-http-after-change-function)
(url-current-object url-as-http))
(url-https-proxy-connect plain-conn))
(sleep-for 0.5)
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@ahyatt ahyatt Sep 5, 2020

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Why is the sleep needed? Can we instead check plain-conn?

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@catern catern Sep 5, 2020

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We need to wait until we get a response to the CONNECT issued by url-https-proxy-connect. The proper (and only) way to do this is with a process-filter. I was just too lazy to hook up that additional possible state into the websocket.el process filter...

(gnutls-negotiate :process plain-conn :hostname host))
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@ahyatt ahyatt Sep 5, 2020

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Is this all a standard sequence of actions for https proxy connections? How would we be sure this is correct?

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@catern catern Sep 5, 2020

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As far as I know it's pretty standard - I figured this out mostly by reading url.el.

We certainly could add a test for this. I looked briefly at https://tinyproxy.github.io/ and it looks like it should support proxying websocket connections. I just didn't get around to it because I wanted to figure out quickly if I could get this working against the internal corporate proxy that I wanted to access.

(condition-case-unless-debug nil
(open-network-stream name nil host port :type type :nowait nowait)
(wrong-number-of-arguments
(signal 'websocket-wss-needs-emacs-24 (list "wss"))))))
(signal 'websocket-wss-needs-emacs-24 (list "wss")))))))
(signal 'websocket-unsupported-protocol (list (url-type url-struct)))))
(websocket (websocket-inner-create
:conn conn
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