kore/examples/sse/src/sse.c

186 lines
4.9 KiB
C
Executable File

/*
* Copyright (c) 2015 Joris Vink <joris@coders.se>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/*
* Simple example of how SSE (Server Side Events) could be used in Kore.
*
* Upon new arrivals, a join event is broadcast to all clients.
* If a client goes away a leave event is broadcasted.
* Each connection gets its own 10 second ping timer which will emit
* a ping event to the connection endpoint.
*/
#include <kore/kore.h>
#include <kore/http.h>
#include "assets.h"
void sse_ping(void *, u_int64_t);
int page(struct http_request *);
int subscribe(struct http_request *);
void sse_disconnect(struct connection *);
void sse_send(struct connection *, void *, size_t);
void sse_broadcast(struct connection *, void *, size_t);
int check_header(struct http_request *, const char *, const char *);
/*
* Each client subscribed to our SSE gets a state attached
* to their hdlr_extra pointer member.
*/
struct sse_state {
struct kore_timer *timer;
};
int
page(struct http_request *req)
{
if (req->method != HTTP_METHOD_GET) {
http_response_header(req, "allow", "get");
http_response(req, 405, NULL, 0);
return (KORE_RESULT_OK);
}
http_response_header(req, "content-type", "text/html");
http_response(req, 200, asset_index_html, asset_len_index_html);
return (KORE_RESULT_OK);
}
int
subscribe(struct http_request *req)
{
struct sse_state *state;
char *hello = "event:join\ndata: client\n\n";
/* Preventive paranoia. */
if (req->hdlr_extra != NULL) {
kore_log(LOG_ERR, "%p: already subscribed", req->owner);
http_response(req, 500, NULL, 0);
return (KORE_RESULT_OK);
}
/* Only allow GET methods. */
if (req->method != HTTP_METHOD_GET) {
http_response_header(req, "allow", "get");
http_response(req, 405, NULL, 0);
return (KORE_RESULT_OK);
}
/* Only do SSE if the client told us it wanted too. */
if (!check_header(req, "accept", "text/event-stream"))
return (KORE_RESULT_OK);
/* Do not include content-length in our response. */
req->flags |= HTTP_REQUEST_NO_CONTENT_LENGTH;
/* Notify existing clients of our new client now. */
sse_broadcast(req->owner, hello, strlen(hello));
/* Set a disconnection method so we know when this client goes away. */
req->owner->disconnect = sse_disconnect;
/* We do not expect any more data to arrive. */
req->owner->flags |= CONN_READ_BLOCK;
/* Allocate a state to be carried by our connection. */
state = kore_malloc(sizeof(*state));
req->owner->hdlr_extra = state;
/* Now start a timer to send a ping back every 10 second. */
state->timer = kore_timer_add(sse_ping, 10000, req->owner, 0);
/* Respond that the SSE channel is now open. */
kore_log(LOG_NOTICE, "%p: connected for SSE", req->owner);
http_response_header(req, "content-type", "text/event-stream");
http_response(req, 200, NULL, 0);
return (KORE_RESULT_OK);
}
void
sse_broadcast(struct connection *src, void *data, size_t len)
{
struct connection *c;
/* Broadcast the message to all other clients. */
TAILQ_FOREACH(c, &connections, list) {
if (c == src)
continue;
sse_send(c, data, len);
}
}
void
sse_send(struct connection *c, void *data, size_t len)
{
struct sse_state *state = c->hdlr_extra;
/* Do not send to clients that do not have a state. */
if (state == NULL)
return;
/* Queue outgoing data now. */
net_send_queue(c, data, len);
net_send_flush(c);
}
void
sse_ping(void *arg, u_int64_t now)
{
struct connection *c = arg;
char *ping = "event:ping\ndata:\n\n";
/* Send our ping to the client. */
sse_send(c, ping, strlen(ping));
}
void
sse_disconnect(struct connection *c)
{
struct sse_state *state = c->hdlr_extra;
char *leaving = "event: leave\ndata: client\n\n";
kore_log(LOG_NOTICE, "%p: disconnecting for SSE", c);
/* Tell others we are leaving. */
sse_broadcast(c, leaving, strlen(leaving));
/* Kill our timer and free/remove the state. */
kore_timer_remove(state->timer);
kore_free(state);
/* Prevent us to be called again. */
c->hdlr_extra = NULL;
c->disconnect = NULL;
}
int
check_header(struct http_request *req, const char *name, const char *value)
{
const char *hdr;
if (!http_request_header(req, name, &hdr)) {
http_response(req, 400, NULL, 0);
return (KORE_RESULT_ERROR);
}
if (strcmp(hdr, value)) {
http_response(req, 400, NULL, 0);
return (KORE_RESULT_ERROR);
}
return (KORE_RESULT_OK);
}