Add websockets surface module

libs/surfaces/websockets/server.cc

@@ -0,0 +1,383 @@
+/*
+ * Copyright (C) 2020 Luciano Iam <lucianito@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the/GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef DEBUG
+#include <iostream>
+#endif
+
+#include "server.h"
+#include "dispatcher.h"
+
+using namespace Glib;
+
+WebsocketsServer::WebsocketsServer
+    (ArdourSurface::ArdourWebsockets& surface)
+    : SurfaceComponent (surface)
+    , _lws_context (0)
+{
+    // keep references to all config for libwebsockets 2
+    _lws_proto[0] = {
+        "lws-ardour", // name
+        WebsocketsServer::lws_callback, // callback
+        0,  // per_session_data_size
+        0,  // rx_buffer_size
+        0,  // id
+        0,  // user
+#if LWS_LIBRARY_VERSION_MAJOR >= 3
+        0   // tx_packet_size
+#endif
+    };
+    _lws_proto[1] = {}; // sentinel
+
+    _lws_info = {};
+    _lws_info.port = WEBSOCKET_LISTEN_PORT;
+    _lws_info.protocols = _lws_proto;
+    _lws_info.uid  = -1;
+    _lws_info.gid  = -1;
+    _lws_info.user = this;
+}
+
+int
+WebsocketsServer::start ()
+{
+    _lws_context = lws_create_context (&_lws_info);
+
+    if (!_lws_context) {
+        PBD::error << "ArdourWebsockets: could not create libwebsockets context" << endmsg;
+        return -1;
+    }
+
+    // add_poll_fd() should have been called once during lws_create_context()
+    // if _fd_ctx is empty then LWS_CALLBACK_ADD_POLL_FD was not called
+    // this means libwesockets was not compiled with LWS_WITH_EXTERNAL_POLL
+    // - macos homebrew libwebsockets: disabled (3.2.2 as of Feb 2020)
+    // - linux ubuntu libwebsockets-dev: enabled (2.0.3 as of Feb 2020) but
+    //   #if defined(LWS_WITH_EXTERNAL_POLL) check is not reliable -- constant
+    //   missing from /usr/include/lws_config.h
+
+    if (_fd_ctx.empty ()) {
+        PBD::error << "ArdourWebsockets: check your libwebsockets was compiled"
+            " with LWS_WITH_EXTERNAL_POLL enabled" << endmsg;
+        return -1;
+    }
+
+    return 0;
+}
+
+int
+WebsocketsServer::stop ()
+{
+    for (LwsPollFdGlibSourceMap::iterator it = _fd_ctx.begin (); it != _fd_ctx.end (); ++it) {
+        it->second.rg_iosrc->destroy ();
+
+        if (it->second.wg_iosrc) {
+            it->second.wg_iosrc->destroy ();
+        }
+    }
+
+    _fd_ctx.clear ();
+
+    if (_lws_context) {
+        lws_context_destroy (_lws_context);
+        _lws_context = 0;
+    }
+
+    return 0;
+}
+
+void
+WebsocketsServer::update_client (Client wsi, const NodeState& state, bool force)
+{
+    ClientContextMap::iterator it = _client_ctx.find (wsi);
+    if (it == _client_ctx.end ()) {
+        return;
+    }
+
+    if (force || !it->second.has_state (state)) {
+        // write to client only if state was updated
+        it->second.update_state (state);
+        it->second.output_buf ().push_back (NodeStateMessage { state });
+        lws_callback_on_writable (wsi);
+    }
+}
+
+void
+WebsocketsServer::update_all_clients (const NodeState& state, bool force)
+{    
+    for (ClientContextMap::iterator it = _client_ctx.begin (); it != _client_ctx.end (); ++it) {
+        update_client (it->second.wsi (), state, force);
+    }
+}
+
+void
+WebsocketsServer::add_poll_fd (struct lws_pollargs *pa)
+{
+    // fd can be SOCKET or int depending platform
+    lws_sockfd_type fd = pa->fd;
+
+#ifdef PLATFORM_WINDOWS
+    RefPtr<IOChannel> g_channel = IOChannel::create_from_win32_socket (fd);
+#else
+    RefPtr<IOChannel> g_channel = IOChannel::create_from_fd (fd);
+#endif
+    RefPtr<IOSource> rg_iosrc { IOSource::create (g_channel, events_to_ioc (pa->events)) };
+    rg_iosrc->connect (sigc::bind (sigc::mem_fun (*this, &WebsocketsServer::io_handler), fd));
+    rg_iosrc->attach (main_loop ()->get_context ());
+
+    struct lws_pollfd lws_pfd;
+    lws_pfd.fd = pa->fd;
+    lws_pfd.events = pa->events;
+    lws_pfd.revents = 0;
+    _fd_ctx[fd] = LwsPollFdGlibSource { lws_pfd, g_channel, rg_iosrc, { } };
+}
+
+void
+WebsocketsServer::mod_poll_fd (struct lws_pollargs *pa)
+{
+    LwsPollFdGlibSourceMap::iterator it = _fd_ctx.find (pa->fd);
+    if (it == _fd_ctx.end ()) {
+        return;
+    }
+
+    it->second.lws_pfd.events = pa->events;
+
+    if (pa->events & POLLOUT) {
+        // libwebsockets wants to write but cannot find a way to update
+        // an existing glib::iosource event flags using glibmm,
+        // create another iosource and set to IO_OUT, it will be destroyed
+        // after clearing POLLOUT (see 'else' body below)
+
+        if (it->second.wg_iosrc) {
+            // already polling for write
+            return;
+        }
+
+        RefPtr<IOSource> wg_iosrc = it->second.g_channel->create_watch (IOCondition::IO_OUT);
+        wg_iosrc->connect (sigc::bind (sigc::mem_fun (*this, &WebsocketsServer::io_handler), pa->fd));
+        wg_iosrc->attach (main_loop ()->get_context ());
+        it->second.wg_iosrc = wg_iosrc;
+    } else {
+        if (it->second.wg_iosrc) {
+            it->second.wg_iosrc->destroy ();
+            it->second.wg_iosrc = { };
+        }
+    }
+}
+
+void
+WebsocketsServer::del_poll_fd (struct lws_pollargs *pa)
+{
+    LwsPollFdGlibSourceMap::iterator it = _fd_ctx.find (pa->fd);
+    if (it == _fd_ctx.end ()) {
+        return;
+    }
+
+    it->second.rg_iosrc->destroy ();
+
+    if (it->second.wg_iosrc) {
+        it->second.wg_iosrc->destroy ();
+    }
+
+    _fd_ctx.erase (it);
+}
+
+void
+WebsocketsServer::add_client (Client wsi)
+{
+    _client_ctx.emplace (wsi, ClientContext { wsi });
+    dispatcher ().update_all_nodes (wsi);   // send all state
+}
+
+void
+WebsocketsServer::del_client (Client wsi)
+{
+    ClientContextMap::iterator it = _client_ctx.find (wsi);
+    if (it != _client_ctx.end ()) {
+        _client_ctx.erase (it);
+    }
+}
+
+void
+WebsocketsServer::recv_client (Client wsi, void *buf, size_t len)
+{
+    NodeStateMessage msg { buf, len };
+    if (!msg.is_valid ()) {
+        return;
+    }
+
+#ifdef DEBUG
+    std::cerr << "RX " << msg.state ().debug_str () << std::endl;
+#endif
+
+    ClientContextMap::iterator it = _client_ctx.find (wsi);
+    if (it == _client_ctx.end ()) {
+        return;
+    }
+
+    // avoid echo
+    it->second.update_state (msg.state ());
+
+    dispatcher ().dispatch (wsi, msg);
+}
+
+void
+WebsocketsServer::write_client (Client wsi)
+{
+    ClientContextMap::iterator it = _client_ctx.find (wsi);
+    if (it == _client_ctx.end ()) {
+        return;
+    }
+
+    ClientOutputBuffer& pending = it->second.output_buf ();
+    if (pending.empty ()) {
+        return;
+    }
+
+    // one lws_write() call per LWS_CALLBACK_SERVER_WRITEABLE callback
+
+    NodeStateMessage msg = pending.front ();
+    pending.pop_front ();
+
+    unsigned char out_buf[1024];
+    size_t len = msg.serialize (out_buf + LWS_PRE, 1024 - LWS_PRE);
+
+    if (len > 0) {
+#ifdef DEBUG
+        std::cerr << "TX " << msg.state ().debug_str () << std::endl;
+#endif
+        lws_write (wsi, out_buf + LWS_PRE, len, LWS_WRITE_TEXT);
+    } else {
+        PBD::error << "ArdourWebsockets: cannot serialize message" << endmsg;
+    }
+
+    if (!pending.empty ()) {
+        lws_callback_on_writable (wsi);
+    }
+}
+
+bool
+WebsocketsServer::io_handler (Glib::IOCondition ioc, lws_sockfd_type fd)
+{
+    // IO_IN=1, IO_PRI=2, IO_ERR=8, IO_HUP=16
+    //printf ("io_handler ioc = %d\n", ioc);
+
+    LwsPollFdGlibSourceMap::iterator it = _fd_ctx.find (fd);
+    if (it == _fd_ctx.end ()) {
+        return false;
+    }
+
+    struct lws_pollfd *lws_pfd = &it->second.lws_pfd;
+    lws_pfd->revents = ioc_to_events (ioc);
+
+    if (lws_service_fd (_lws_context, lws_pfd) < 0) {
+        return false;
+    }
+
+    return ioc & (IO_IN | IO_OUT);
+}
+
+IOCondition
+WebsocketsServer::events_to_ioc (int events)
+{
+    IOCondition ioc = { };
+
+    if (events & POLLIN) {
+        ioc |= IO_IN;
+    }
+
+    if (events & POLLOUT) {
+        ioc |= IO_OUT;
+    }
+
+    if (events & POLLHUP) {
+        ioc |= IO_HUP;
+    }
+
+    if (events & POLLERR) {
+        ioc |= IO_ERR;
+    }
+
+    return ioc;
+}
+
+int 
+WebsocketsServer::ioc_to_events (IOCondition ioc)
+{
+    int events = 0;
+
+    if (ioc & IO_IN) {
+        events |= POLLIN;
+    }
+
+    if (ioc & IO_OUT) {
+        events |= POLLOUT;
+    }
+
+    if (ioc & IO_HUP) {
+        events |= POLLHUP;
+    }
+
+    if (ioc & IO_ERR) {
+        events |= POLLERR;
+    }
+
+    return events;
+}
+
+int
+WebsocketsServer::lws_callback(struct lws* wsi, enum lws_callback_reasons reason,
+            void *user, void *in, size_t len)
+{
+    void *ctx_userdata = lws_context_user (lws_get_context (wsi));
+    WebsocketsServer *server = static_cast<WebsocketsServer *>(ctx_userdata);
+
+    switch (reason) {
+    case LWS_CALLBACK_ADD_POLL_FD:
+        server->add_poll_fd (static_cast<struct lws_pollargs *>(in));
+        break;
+    
+    case LWS_CALLBACK_CHANGE_MODE_POLL_FD:
+        server->mod_poll_fd (static_cast<struct lws_pollargs *>(in));
+        break;
+
+    case LWS_CALLBACK_DEL_POLL_FD:
+        server->del_poll_fd (static_cast<struct lws_pollargs *>(in));
+        break;
+
+    case LWS_CALLBACK_ESTABLISHED:
+        server->add_client (wsi);
+        break;
+
+    case LWS_CALLBACK_CLOSED:
+        server->del_client (wsi);
+        break;
+
+    case LWS_CALLBACK_RECEIVE:
+        server->recv_client (wsi, in, len);
+        break;
+
+    case LWS_CALLBACK_SERVER_WRITEABLE:
+        server->write_client (wsi);
+        break;
+
+    default:
+        break;
+    }
+
+    return 0;
+}