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Add WebSocket demo that uses asynchronous messages from the server.

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William Greathouse
2013-09-09 13:06:03 -04:00
committed by Thomas Davis
parent aa51d80d24
commit aa7c2a1b8c
3 changed files with 641 additions and 0 deletions
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examples/ws_server/ws_server.c Normal file
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// Copyright (c) 2004-2012 Sergey Lyubka
// This file is a part of civetweb project, http://github.com/sunsetbrew/civetweb
//
// v 0.1 Contributed by William Greathouse 9-Sep-2013
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "civetweb.h"
// simple structure for keeping track of websocket connection
struct ws_connection {
struct mg_connection *conn;
int update;
int closing;
};
// time base and structure periodic updates to client for demo
#define BASETIME 100000 /* 0.1 seconds */
struct progress {
int limit;
int increment;
int period;
int value;
};
// up to 16 independent client connections
#define CONNECTIONS 16
static struct ws_connection ws_conn[CONNECTIONS];
// ws_server_thread()
// Simple demo server thread. Sends periodic updates to connected clients
static void *ws_server_thread(void *parm)
{
int wsd = (long)parm;
struct mg_connection *conn = ws_conn[wsd].conn;
int timer = 0;
char tstr[32];
int i;
struct progress meter[] = {
/* first meter 0 to 1000, by 5 every 0.1 second */
{ 1000, 5, 1, 0 },
/* second meter 0 to 500, by 10 every 0.5 second */
{ 500, 10, 5, 0 },
/* third meter 0 to 100, by 10 every 1.0 second */
{ 100, 10, 10, 0},
/* end of list */
{ 0, 0, 0, 0}
};
fprintf(stderr, "ws_server_thread %d\n", wsd);
/* Send initial meter updates */
for (i=0; meter[i].period != 0; i++)
{
if (meter[i].value >= meter[i].limit)
meter[i].value = 0;
if (meter[i].value >= meter[i].limit)
meter[i].value = meter[i].limit;
sprintf(tstr, "meter%d:%d,%d", i+1,
meter[i].value, meter[i].limit);
mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, tstr, strlen(tstr));
}
/* While the connection is open, send periodic updates */
while(!ws_conn[wsd].closing)
{
usleep(100000); /* 0.1 second */
timer++;
/* Send meter updates */
if (ws_conn[wsd].update)
{
for (i=0; meter[i].period != 0; i++)
{
if (timer%meter[i].period == 0)
{
if (meter[i].value >= meter[i].limit)
meter[i].value = 0;
else
meter[i].value += meter[i].increment;
if (meter[i].value >= meter[i].limit)
meter[i].value = meter[i].limit;
// if we are closing, server should not send new data
if (!ws_conn[wsd].closing)
{
sprintf(tstr, "meter%d:%d,%d", i+1,
meter[i].value, meter[i].limit);
mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, tstr, strlen(tstr));
}
}
}
}
/* Send periodic PING to assure websocket remains connected, except if we are closing */
if (timer%100 == 0 && !ws_conn[wsd].closing)
mg_websocket_write(conn, WEBSOCKET_OPCODE_PING, NULL, 0);
}
fprintf(stderr, "ws_server_thread %d exiting\n", wsd);
// reset connection information to allow reuse by new client
ws_conn[wsd].conn = NULL;
ws_conn[wsd].update = 0;
ws_conn[wsd].closing = 2;
return NULL;
}
// websocket_connect_handler()
// On new client connection, find next available server connection and store
// new connection information. If no more server connections are available
// tell civetweb to not accept the client request.
static int websocket_connect_handler(const struct mg_connection *conn) {
int i;
fprintf(stderr, "connect handler\n");
for(i=0; i < CONNECTIONS; ++i)
{
if (ws_conn[i].conn == NULL)
{
fprintf(stderr, "...prep for server %d\n", i);
ws_conn[i].conn = (struct mg_connection *)conn;
ws_conn[i].closing = 0;
ws_conn[i].update = 0;
break;
}
}
if (i >= CONNECTIONS)
{
fprintf(stderr, "Refused connection: Max connections exceeded\n");
return 1;
}
return 0;
}
// websocket_ready_handler()
// Once websocket negotiation is complete, start a server for the connection
static void websocket_ready_handler(struct mg_connection *conn) {
int i;
fprintf(stderr, "ready handler\n");
for(i=0; i < CONNECTIONS; ++i)
{
if (ws_conn[i].conn == conn)
{
fprintf(stderr, "...start server %d\n", i);
mg_start_thread(ws_server_thread, (void *)(long)i);
break;
}
}
}
// websocket_close_handler()
// When websocket is closed, tell the associated server to shut down
static void websocket_close_handler(struct mg_connection *conn) {
int i;
//fprintf(stderr, "close handler\n"); /* called for every close, not just websockets */
for(i=0; i < CONNECTIONS; ++i)
{
if (ws_conn[i].conn == conn)
{
fprintf(stderr, "...close server %d\n", i);
ws_conn[i].closing = 1;
}
}
}
// Arguments:
// flags: first byte of websocket frame, see websocket RFC,
// http://tools.ietf.org/html/rfc6455, section 5.2
// data, data_len: payload data. Mask, if any, is already applied.
static int websocket_data_handler(struct mg_connection *conn, int flags,
char *data, size_t data_len) {
int i;
int wsd;
for(i=0; i < CONNECTIONS; ++i)
{
if (ws_conn[i].conn == conn)
{
wsd = i;
break;
}
}
if (i >= CONNECTIONS)
{
fprintf(stderr, "Received websocket data from unknown connection\n");
return 1;
}
if (flags & 0x80)
{
flags &= 0x7f;
switch (flags)
{
case WEBSOCKET_OPCODE_CONTINUATION:
fprintf(stderr, "CONTINUATION...\n");
break;
case WEBSOCKET_OPCODE_TEXT:
fprintf(stderr, "TEXT: %-.*s\n", (int)data_len, data);
/*** interpret data as commands here ***/
if (strncmp("update on", data, data_len)== 0)
{
/* turn on updates */
ws_conn[wsd].update = 1;
/* echo back */
mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, data, data_len);
}
else if (strncmp("update off", data, data_len)== 0)
{
/* turn off updates */
ws_conn[wsd].update = 0;
/* echo back */
mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, data, data_len);
}
break;
case WEBSOCKET_OPCODE_BINARY:
fprintf(stderr, "BINARY...\n");
break;
case WEBSOCKET_OPCODE_CONNECTION_CLOSE:
fprintf(stderr, "CLOSE...\n");
/* If client initiated close, respond with close message in acknowlegement */
if (!ws_conn[wsd].closing)
{
mg_websocket_write(conn, WEBSOCKET_OPCODE_CONNECTION_CLOSE, data, data_len);
ws_conn[wsd].closing = 1; /* we should not send addional messages when close requested/acknowledged */
}
return 0; /* time to close the connection */
break;
case WEBSOCKET_OPCODE_PING:
/* client sent PING, respond with PONG */
mg_websocket_write(conn, WEBSOCKET_OPCODE_PONG, data, data_len);
break;
case WEBSOCKET_OPCODE_PONG:
/* received PONG to our PING, no action */
break;
default:
fprintf(stderr, "Unknown flags: %02x\n", flags);
break;
}
}
return 1; /* keep connection open */
}
int main(void)
{
char server_name[40];
struct mg_context *ctx;
struct mg_callbacks callbacks;
const char *options[] = {
"listening_ports", "8080",
"document_root", "docroot",
NULL
};
/* get simple greeting for the web server */
snprintf(server_name, sizeof(server_name),
"Civetweb websocket server v. %s",
mg_version());
memset(&callbacks, 0, sizeof(callbacks));
callbacks.websocket_connect = websocket_connect_handler;
callbacks.websocket_ready = websocket_ready_handler;
callbacks.websocket_data = websocket_data_handler;
callbacks.connection_close = websocket_close_handler;
ctx = mg_start(&callbacks, NULL, options);
/* show the greeting and some basic information */
printf("%s started on port(s) %s with web root [%s]\n",
server_name, mg_get_option(ctx, "listening_ports"),
mg_get_option(ctx, "document_root"));
getchar(); // Wait until user hits "enter"
mg_stop(ctx);
return 0;
}