[web] Support libevent as WS server instead of libwebsockets #1818
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If libevent >= 2.2 is detected during configure and "websocket_port" == 0 in the config file, the libwebsocket implementation is disabled and instead the libevent http server offers the websocket connection. The connection to the websocket is then done with the path "/ws".
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Sounds really promising. Too bad that the libevent team is slow at releasing versions of their library; last commit was last year. |
Yes, more frequent releases of libevent would be nice. Especially because it also takes quite a long time until all the distros pick up the new release. |
| [event_base_new], [event2/event.h]) | ||
| [event_base_new], [event2/event.h], | ||
| [dnl check for version 2.2 (with websocket server support) | ||
| PKG_CHECK_EXISTS([libevent >= 2.2.1], |
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Is it possible to do a feature check instead of a version check?
| return json_response; | ||
| } | ||
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| /* Thread: library (the thread the event occurred) */ |
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I think this would also be called from other threads than the library thread
| struct client *client = NULL; | ||
| char *reply = NULL; | ||
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| for (client = clients; client; client = clients->next) |
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Doesn't look thread safe to me since clients is a global? And is evws_send_text safe to call with ->evws, which looks like it belongs to the httpd thread's evhttp?
| return -1; | ||
| } | ||
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| DPRINTF(E_DBG, L_WEB, "notify callback request: %s\n", json_object_to_json_string(request)); |
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I suggest commenting this out, it's usually quite "noisy"
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| evhttp_set_cb(evhttp, "/ws", gencb_ws, NULL); | ||
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| listener_add(listener_cb, LISTENER_UPDATE | LISTENER_DATABASE | LISTENER_PAIRING | LISTENER_SPOTIFY | LISTENER_LASTFM |
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Maybe we should have a LISTENER_ALL?
| @@ -38,6 +38,7 @@ | |||
| #include "logger.h" | |||
| #include "commands.h" | |||
| #include "httpd_internal.h" | |||
| #include "websocket_ev.h" | |||
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websocket_ev.c isn't that much code, and since it's tied to libevent's evhttp and not called from anywhere else, you could just add it here in httpd_libevent.c?
| DPRINTF(E_DBG, L_WEB, "notify callback reply: %d\n", events); | ||
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| notify = json_object_new_array(); | ||
| if (events & LISTENER_UPDATE) |
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A map might be a good idea, could then also be used in process_notify_request
The next planned minor release 2.2 of libevent will have support for running a websocket server. I thought, I give it a try and see if it works in OwnTone and check if it is something worth adding :-)
The changes in this PR add a libevent based websocket server, that accepts connections under the path
/ws(and the same port as the web interface).If libevent >= 2.2 is detected during configure and "websocket_port" == 0 in the config file, the libwebsocket implementation is disabled and instead the libevent websocket server is active.
The web interface was updated to attempt a WS connection to
/wsif websocket_port == 0.The advantages in using libevent are - if it proves to be reliable - that the libwebsocket dependency could be removed. Additionally, only having one port for the web interface, will make it easier to use a reverse proxy with OwnTone (especially if the reverse proxy is running on the same host).
I did some short tests, and it seems to be working fine, but more tests are required.
I tested it locally and by building an OwnTone container with libevent from git-master (https://github.com/chme/owntone-container/tree/feat/libevent-git). Also I am unsure how it will work with the multi threading support of the http server in OwnTone.
Currently only an alpha release of libevent 2.2 is available (https://github.com/libevent/libevent/releases/tag/release-2.2.1-alpha) . Note, that the libevent 2.2.1 alpha release contains a bug that prevents ws connections from Firefox (Chrome is working fine). The bug is already fixed in the master branch of libevent.