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[web] Implement libevent ws in httpd_libeventhttp, address thread safety
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@chme
chme committed Dec 27, 2024
1 parent 27c9224 commit f2e4819
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Showing 5 changed files with 303 additions and 351 deletions.
1 change: 0 additions & 1 deletion src/Makefile.am
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Original file line number Diff line number Diff line change
Expand Up @@ -130,7 +130,6 @@ owntone_SOURCES = main.c \
listener.c listener.h \
commands.c commands.h \
outputs/plist_wrap.h \
websocket_ev.c websocket_ev.h \
$(LIBWEBSOCKETS_SRC) \
$(GPERF_SRC) \
$(LEXER_SRC) $(PARSER_SRC)
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303 changes: 300 additions & 3 deletions src/httpd_libevhttp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
# include <config.h>
#endif

#include <json.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
Expand All @@ -31,14 +32,18 @@
#include <event2/keyvalq_struct.h>
#include <event2/buffer.h>
#include <event2/bufferevent.h>
#ifdef HAVE_LIBEVENT22
#include <event2/ws.h>
#endif

#include <pthread.h>

#include "conffile.h"
#include "misc.h"
#include "listener.h"
#include "logger.h"
#include "commands.h"
#include "httpd_internal.h"
#include "websocket_ev.h"

// #define DEBUG_ALLOC 1

Expand Down Expand Up @@ -95,6 +100,294 @@ static void
closecb_worker(evutil_socket_t fd, short event, void *arg);


#ifdef HAVE_LIBEVENT22

/*
* Each session of the "notify" protocol holds this event mask
*
* The client sends the events it wants to be notified of and the event mask is
* set accordingly translating them to the LISTENER enum (see listener.h)
*/
struct ws_client
{
struct evws_connection *evws;
char name[INET6_ADDRSTRLEN];
short requested_events;
struct ws_client *next;
};
static struct ws_client *ws_clients = NULL;

/*
* Notify clients of the notify-protocol about occurred events
*
* Sends a JSON message of the form:
*
* {
* "notify": [ "update" ]
* }
*/
static char *
ws_create_notify_reply(short events, short *requested_events)
{
char *json_response;
json_object *reply;
json_object *notify;

DPRINTF(E_DBG, L_WEB, "notify callback reply: %d\n", events);

notify = json_object_new_array();
if (events & LISTENER_UPDATE)
{
json_object_array_add(notify, json_object_new_string("update"));
}
if (events & LISTENER_DATABASE)
{
json_object_array_add(notify, json_object_new_string("database"));
}
if (events & LISTENER_PAIRING)
{
json_object_array_add(notify, json_object_new_string("pairing"));
}
if (events & LISTENER_SPOTIFY)
{
json_object_array_add(notify, json_object_new_string("spotify"));
}
if (events & LISTENER_LASTFM)
{
json_object_array_add(notify, json_object_new_string("lastfm"));
}
if (events & LISTENER_SPEAKER)
{
json_object_array_add(notify, json_object_new_string("outputs"));
}
if (events & LISTENER_PLAYER)
{
json_object_array_add(notify, json_object_new_string("player"));
}
if (events & LISTENER_OPTIONS)
{
json_object_array_add(notify, json_object_new_string("options"));
}
if (events & LISTENER_VOLUME)
{
json_object_array_add(notify, json_object_new_string("volume"));
}
if (events & LISTENER_QUEUE)
{
json_object_array_add(notify, json_object_new_string("queue"));
}

reply = json_object_new_object();
json_object_object_add(reply, "notify", notify);

json_response = strdup(json_object_to_json_string(reply));

json_object_put(reply);

return json_response;
}

/* Thread: library, player, etc. (the thread the event occurred) */
static enum command_state
ws_listener_cb(void *arg, int *ret)
{
struct ws_client *client = NULL;
char *reply = NULL;
short *event_mask = arg;

for (client = ws_clients; client; client = ws_clients->next)
{
reply = ws_create_notify_reply(*event_mask, &client->requested_events);
evws_send_text(client->evws, reply);
free(reply);
}
return COMMAND_END;
}

static void
listener_cb(short event_mask, void *ctx)
{
httpd_server *server = ctx;
commands_exec_sync(server->cmdbase, ws_listener_cb, NULL, &event_mask);
}

/*
* Processes client requests to the notify-protocol
*
* Expects the message in "in" to be a JSON string of the form:
*
* {
* "notify": [ "update" ]
* }
*/
static int
ws_process_notify_request(short *requested_events, const char *in, size_t len)
{
json_tokener *tokener;
json_object *request;
json_object *item;
int count, i;
enum json_tokener_error jerr;
json_object *needle;
const char *event_type;

*requested_events = 0;

tokener = json_tokener_new();
request = json_tokener_parse_ex(tokener, in, len);
jerr = json_tokener_get_error(tokener);

if (jerr != json_tokener_success)
{
DPRINTF(E_LOG, L_WEB, "Failed to parse incoming request: %s\n", json_tokener_error_desc(jerr));
json_tokener_free(tokener);
return -1;
}

DPRINTF(E_DBG, L_WEB, "notify callback request: %s\n", json_object_to_json_string(request));

if (json_object_object_get_ex(request, "notify", &needle) && json_object_get_type(needle) == json_type_array)
{
count = json_object_array_length(needle);
for (i = 0; i < count; i++)
{
item = json_object_array_get_idx(needle, i);

if (json_object_get_type(item) == json_type_string)
{
event_type = json_object_get_string(item);
DPRINTF(E_SPAM, L_WEB, "notify callback event received: %s\n", event_type);

if (0 == strcmp(event_type, "update"))
{
*requested_events |= LISTENER_UPDATE;
}
else if (0 == strcmp(event_type, "database"))
{
*requested_events |= LISTENER_DATABASE;
}
else if (0 == strcmp(event_type, "pairing"))
{
*requested_events |= LISTENER_PAIRING;
}
else if (0 == strcmp(event_type, "spotify"))
{
*requested_events |= LISTENER_SPOTIFY;
}
else if (0 == strcmp(event_type, "lastfm"))
{
*requested_events |= LISTENER_LASTFM;
}
else if (0 == strcmp(event_type, "outputs"))
{
*requested_events |= LISTENER_SPEAKER;
}
else if (0 == strcmp(event_type, "player"))
{
*requested_events |= LISTENER_PLAYER;
}
else if (0 == strcmp(event_type, "options"))
{
*requested_events |= LISTENER_OPTIONS;
}
else if (0 == strcmp(event_type, "volume"))
{
*requested_events |= LISTENER_VOLUME;
}
else if (0 == strcmp(event_type, "queue"))
{
*requested_events |= LISTENER_QUEUE;
}
}
}
}

json_tokener_free(tokener);
json_object_put(request);

return 0;
}

static void
ws_client_msg_cb(struct evws_connection *evws, int type, const unsigned char *data, size_t len, void *arg)
{
struct ws_client *self = arg;
const char *msg = (const char *)data;

ws_process_notify_request(&self->requested_events, msg, len);
}

static void
ws_client_close_cb(struct evws_connection *evws, void *arg)
{
struct ws_client *client = NULL;
struct ws_client *prev = NULL;

for (client = ws_clients; client && client != arg; client = ws_clients->next)
{
prev = client;
}

if (client)
{
if (prev)
prev->next = client->next;
else
ws_clients = client->next;

free(client);
}
}

static void
ws_gencb(struct evhttp_request *req, void *arg)
{
struct ws_client *client;

client = calloc(1, sizeof(*client));

client->evws = evws_new_session(req, ws_client_msg_cb, client, 0);
if (!client->evws)
{
free(client);
return;
}

evws_connection_set_closecb(client->evws, ws_client_close_cb, client);
client->next = ws_clients;
ws_clients = client;
}

static int
ws_init(httpd_server *server)
{
int websocket_port = cfg_getint(cfg_getsec(cfg, "general"), "websocket_port");

if (websocket_port > 0)
{
DPRINTF(E_DBG, L_WEB,
"Libevent websocket disabled, using libwebsockets instead. Set "
"websocket_port to 0 to enable it.\n");
return 0;
}

evhttp_set_cb(server->evhttp, "/ws", ws_gencb, NULL);

listener_add(listener_cb, LISTENER_UPDATE | LISTENER_DATABASE | LISTENER_PAIRING | LISTENER_SPOTIFY | LISTENER_LASTFM
| LISTENER_SPEAKER | LISTENER_PLAYER | LISTENER_OPTIONS | LISTENER_VOLUME
| LISTENER_QUEUE, server);

return 0;
}

static void
ws_deinit(void)
{
listener_remove(listener_cb);
}
#endif


const char *
httpd_query_value_find(httpd_query *query, const char *key)
{
Expand Down Expand Up @@ -345,7 +638,9 @@ httpd_server_free(httpd_server *server)

if (server->evhttp)
{
websocketev_deinit();
#ifdef HAVE_LIBEVENT22
ws_deinit();
#endif
evhttp_free(server->evhttp);
}

Expand Down Expand Up @@ -380,7 +675,9 @@ httpd_server_new(struct event_base *evbase, unsigned short port, httpd_request_c
goto error;

evhttp_set_gencb(server->evhttp, gencb_httpd, server);
websocketev_init(server->evhttp);
#ifdef HAVE_LIBEVENT22
ws_init(server);
#endif

return server;

Expand Down
6 changes: 3 additions & 3 deletions src/websocket.c
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Original file line number Diff line number Diff line change
Expand Up @@ -48,7 +48,7 @@ static pthread_mutex_t websocket_write_event_lock;
static short websocket_write_events;


/* Thread: library (the thread the event occurred) */
/* Thread: library, player, etc. (the thread the event occurred) */
static void
listener_cb(short event_mask, void *ctx)
{
Expand Down Expand Up @@ -133,7 +133,7 @@ process_notify_request(short *requested_events, void *in, size_t len)
if (json_object_get_type(item) == json_type_string)
{
event_type = json_object_get_string(item);
DPRINTF(E_DBG, L_WEB, "notify callback event received: %s\n", event_type);
DPRINTF(E_SPAM, L_WEB, "notify callback event received: %s\n", event_type);

if (0 == strcmp(event_type, "update"))
{
Expand Down Expand Up @@ -279,7 +279,7 @@ callback_notify(struct lws *wsi, enum lws_callback_reasons reason, void *user, v
short events = 0;
int ret = 0;

DPRINTF(E_DBG, L_WEB, "notify callback reason: %d\n", reason);
DPRINTF(E_SPAM, L_WEB, "notify callback reason: %d\n", reason);

switch (reason)
{
Expand Down
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