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/*
* ws protocol handler plugin for "lws-minimal"
*
* Written in 2010-2019 by Andy Green <andy@warmcat.com>
*
* This file is made available under the Creative Commons CC0 1.0
* Universal Public Domain Dedication.
*
* This version holds a single message at a time, which may be lost if a new
* message comes. See the minimal-ws-server-ring sample for the same thing
* but using an lws_ring ringbuffer to hold up to 8 messages at a time.
*/
#if !defined (LWS_PLUGIN_STATIC)
#define LWS_DLL
#define LWS_INTERNAL
#include <libwebsockets.h>
#endif
#include <string.h>
/* one of these created for each message */
struct msg {
void *payload; /* is malloc'd */
size_t len;
};
/* one of these is created for each client connecting to us */
struct per_session_data__minimal {
struct per_session_data__minimal *pss_list;
struct lws *wsi;
int last; /* the last message number we sent */
};
/* one of these is created for each vhost our protocol is used with */
struct per_vhost_data__minimal {
struct lws_context *context;
struct lws_vhost *vhost;
const struct lws_protocols *protocol;
struct per_session_data__minimal *pss_list; /* linked-list of live pss*/
struct msg amsg; /* the one pending message... */
int current; /* the current message number we are caching */
};
/* destroys the message when everyone has had a copy of it */
static void
__minimal_destroy_message(void *_msg)
{
struct msg *msg = _msg;
free(msg->payload);
msg->payload = NULL;
msg->len = 0;
}
static int
callback_minimal(struct lws *wsi, enum lws_callback_reasons reason,
void *user, void *in, size_t len)
{
struct per_session_data__minimal *pss =
(struct per_session_data__minimal *)user;
struct per_vhost_data__minimal *vhd =
(struct per_vhost_data__minimal *)
lws_protocol_vh_priv_get(lws_get_vhost(wsi),
lws_get_protocol(wsi));
int m;
switch (reason) {
case LWS_CALLBACK_PROTOCOL_INIT:
vhd = lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi),
lws_get_protocol(wsi),
sizeof(struct per_vhost_data__minimal));
vhd->context = lws_get_context(wsi);
vhd->protocol = lws_get_protocol(wsi);
vhd->vhost = lws_get_vhost(wsi);
break;
case LWS_CALLBACK_ESTABLISHED:
/* add ourselves to the list of live pss held in the vhd */
pss->pss_list = vhd->pss_list;
vhd->pss_list = pss;
pss->wsi = wsi;
pss->last = vhd->current;
break;
case LWS_CALLBACK_CLOSED:
/* remove our closing pss from the list of live pss */
lws_start_foreach_llp(struct per_session_data__minimal **,
ppss, vhd->pss_list) {
if (*ppss == pss) {
*ppss = pss->pss_list;
break;
}
} lws_end_foreach_llp(ppss, pss_list);
break;
case LWS_CALLBACK_SERVER_WRITEABLE:
if (!vhd->amsg.payload)
break;
if (pss->last == vhd->current)
break;
/* notice we allowed for LWS_PRE in the payload already */
m = lws_write(wsi, ((unsigned char *)vhd->amsg.payload) +
LWS_PRE, vhd->amsg.len, LWS_WRITE_TEXT);
if (m < (int)vhd->amsg.len) {
lwsl_err("ERROR %d writing to ws socket\n", m);
return -1;
}
pss->last = vhd->current;
break;
case LWS_CALLBACK_RECEIVE:
if (vhd->amsg.payload)
__minimal_destroy_message(&vhd->amsg);
vhd->amsg.len = len;
/* notice we over-allocate by LWS_PRE */
vhd->amsg.payload = malloc(LWS_PRE + len);
if (!vhd->amsg.payload) {
lwsl_user("OOM: dropping\n");
break;
}
memcpy((char *)vhd->amsg.payload + LWS_PRE, in, len);
vhd->current++;
/*
* let everybody know we want to write something on them
* as soon as they are ready
*/
lws_start_foreach_llp(struct per_session_data__minimal **,
ppss, vhd->pss_list) {
lws_callback_on_writable((*ppss)->wsi);
} lws_end_foreach_llp(ppss, pss_list);
break;
default:
break;
}
return 0;
}
#define LWS_PLUGIN_PROTOCOL_MINIMAL \
{ \
"lws-minimal", \
callback_minimal, \
sizeof(struct per_session_data__minimal), \
128, \
0, NULL, 0 \
}
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