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// Copyright (C) 2021 Russell King.
// Licensed under GPL version 2. See COPYING.
#include <gio/gio.h>
#include "event-httpd.h"
#include "resource.h"
struct resource_object {
GList *client_list;
GString *string;
};
static struct resource_object position_object;
static struct resource_object signal_object;
static void resource_obj_send_one(gpointer data, gpointer user_data)
{
GString *string = user_data;
struct client *c = data;
respond_chunk(c, string);
}
static void resource_obj_send_all(struct resource_object *obj, GString *str)
{
g_list_foreach(obj->client_list, resource_obj_send_one, str);
}
static void resource_obj_set_string(struct resource_object *obj, GString *str)
{
GString *old;
old = obj->string;
obj->string = str;
g_string_free(old, TRUE);
resource_obj_send_all(obj, str);
}
static void resource_obj_add_client(struct resource_object *obj,
struct client *c)
{
obj->client_list = g_list_append(obj->client_list, c);
}
static void resource_obj_del_client(struct resource_object *obj,
struct client *c)
{
obj->client_list = g_list_remove(obj->client_list, c);
}
static GString *object_backend_status(struct resource *r)
{
GString *str;
str = g_string_new("event: backend\n");
g_string_append_printf(str,
"data: {\"status\":\"%s\",\"timestamp\":%ld}\n\n",
r->updater ? "connected" : "disconnected",
r->updater_time);
return str;
}
static int object_v1_get(struct client *c, struct resource *r)
{
struct resource_object *obj = r->data;
GString *str;
respond_header(c, 200, "OK",
"Cache-Control: no-cache\r\n"
"Connection: keep-alive\r\n"
"Content-Type: text/event-stream; charset=UTF-8\r\n"
"Transfer-Encoding: chunked\r\n");
str = object_backend_status(r);
g_string_append(str, "retry: 10000\n");
if (obj->string)
g_string_append_len(str, obj->string->str,
obj->string->len);
respond_chunk(c, str);
g_string_free(str, TRUE);
// Add this client to the object list so it receives updates
resource_obj_add_client(obj, c);
return 1;
}
static void object_v1_close(struct client *c, struct resource *r)
{
struct resource_object *obj = r->data;
// Remove this client from the object list
resource_obj_del_client(obj, c);
}
static void object_v1_update_open(struct client *c, struct resource *r)
{
GString *str;
// Keep track of the latest updater
r->updater = c;
time(&r->updater_time);
str = object_backend_status(r);
resource_obj_send_all(r->data, str);
g_string_free(str, TRUE);
}
// Update all attached clients with the new resource object data
static int object_v1_update(struct client *c, struct resource *r, const char *m)
{
struct resource_object *obj = r->data;
GString *string;
char *n;
// Only allow the latest updater to provide updates, in case we
// end up with multiple connections. This also allows us to quickly
// release the resources of a stale connection.
if (r->updater != c)
return -1;
// Remove any trailing whitespace.
n = g_strchomp(g_strdup(m));
// Format the text/event-stream response
// We prefix the string with the "data:" tag in preparation for
// sending to via the text/event-stream connection.
// The double newline terminates this event
// See https://www.html5rocks.com/en/tutorials/eventsource/basics/
string = g_string_new(NULL);
g_string_printf(string, "data:%s\n\n", n);
g_free(n);
resource_obj_set_string(obj, string);
return 0;
}
static void object_v1_update_close(struct client *c, struct resource *r)
{
GString *str;
// If the updater goes away, clear the data so we don't serve
// stale data.
if (r->updater == c) {
r->updater = NULL;
time(&r->updater_time);
str = object_backend_status(r);
resource_obj_send_all(r->data, str);
g_string_free(str, TRUE);
}
}
static const struct resource_ops resource_v1_ops = {
.get = object_v1_get,
.close = object_v1_close,
.update_open = object_v1_update_open,
.update = object_v1_update,
.update_close = object_v1_update_close,
};
static struct resource resource_position1 = {
.ops = &resource_v1_ops,
.data = &position_object,
};
static struct resource resource_signal1 = {
.ops = &resource_v1_ops,
.data = &signal_object,
};
void resource_init(GHashTable *hash)
{
g_hash_table_insert(hash, "/api/1/position", &resource_position1);
g_hash_table_insert(hash, "/api/1/signal", &resource_signal1);
}
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