martinsik · September 6, 2012 10:03 · linuxdeveloper · Jul 8, 2015 · rragu · Apr 22, 2016
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <html>
    <head>
        <meta charset="utf-8">
        <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
        <script type="text/javascript">
            $(function() {
                window.WebSocket = window.WebSocket || window.MozWebSocket;

                var websocket = new WebSocket('ws://127.0.0.1:9000',
                                              'dumb-increment-protocol');

                websocket.onopen = function () {
                    $('h1').css('color', 'green');
                };

                websocket.onerror = function () {
                    $('h1').css('color', 'red');
                };

                websocket.onmessage = function (message) {
                    console.log(message.data);
                    $('div').append($('<p>', { text: message.data }));
                };
                

                $('button').click(function(e) {
                    e.preventDefault();
                    websocket.send($('input').val());
                    $('input').val('');
                });
            });
        </script>
        </head>
    <body>
        <h1>WebSockets test</h1>
        <form>
            <input type="text" />
            <button>Send</button>
        </form>
        <div></div>
    </body>
 </html>
diff --git a/libwebsockets-websocket.c b/libwebsockets-websocket.c
 #include <stdio.h>
 #include <stdlib.h>
 #include <libwebsockets.h>


 static int callback_http(struct libwebsocket_context * this,
                         struct libwebsocket *wsi,
                         enum libwebsocket_callback_reasons reason, void *user,
                         void *in, size_t len)
 {
 	return 0;
 }



 static int callback_dumb_increment(struct libwebsocket_context * this,
                                   struct libwebsocket *wsi,
                                   enum libwebsocket_callback_reasons reason,
                                   void *user, void *in, size_t len)
 {
    switch (reason) {
        case LWS_CALLBACK_ESTABLISHED: // just log message that someone is connecting
            printf("connection established\n");
            break;
        case LWS_CALLBACK_RECEIVE: { // the funny part
            // create a buffer to hold our response
            // it has to have some pre and post padding. You don't need to care
            // what comes there, libwebsockets will do everything for you. For more info see
            // http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/libwebsockets.h#n597
            unsigned char *buf = (unsigned char*) malloc(LWS_SEND_BUFFER_PRE_PADDING + len +
                                                         LWS_SEND_BUFFER_POST_PADDING);
            
            int i;
            
            // pointer to `void *in` holds the incomming request
            // we're just going to put it in reverse order and put it in `buf` with
            // correct offset. `len` holds length of the request.
            for (i=0; i < len; i++) {
                buf[LWS_SEND_BUFFER_PRE_PADDING + (len - 1) - i ] = ((char *) in)[i];
            }
            
            // log what we recieved and what we're going to send as a response.
            // that disco syntax `%.*s` is used to print just a part of our buffer
            // http://stackoverflow.com/questions/5189071/print-part-of-char-array
            printf("received data: %s, replying: %.*s\n", (char *) in, (int) len,
                   buf + LWS_SEND_BUFFER_PRE_PADDING);
            
            // send response
            // just notice that we have to tell where exactly our response starts. That's
            // why there's `buf[LWS_SEND_BUFFER_PRE_PADDING]` and how long it is.
            // we know that our response has the same length as request because
            // it's the same message in reverse order.
            libwebsocket_write(wsi, &buf[LWS_SEND_BUFFER_PRE_PADDING], len, LWS_WRITE_TEXT);
            
            // release memory back into the wild
            free(buf);
            break;
        }
        default:
            break;
    }
    
    return 0;
 }



 static struct libwebsocket_protocols protocols[] = {
    /* first protocol must always be HTTP handler */
    {
        "http-only",   // name
        callback_http, // callback
        0              // per_session_data_size
    },
    {
        "dumb-increment-protocol", // protocol name - very important!
        callback_dumb_increment,   // callback
        0                          // we don't use any per session data
    },
    {
        NULL, NULL, 0   /* End of list */
    }
 };

 int main(void) {
    // server url will be http://localhost:9000
    int port = 9000;
    const char *interface = NULL;
    struct libwebsocket_context *context;
    // we're not using ssl
    const char *cert_path = NULL;
    const char *key_path = NULL;
    // no special options
    int opts = 0;
    
    // create libwebsocket context representing this server
    context = libwebsocket_create_context(port, interface, protocols,
                                          libwebsocket_internal_extensions,
                                          cert_path, key_path, -1, -1, opts);
    
    if (context == NULL) {
        fprintf(stderr, "libwebsocket init failed\n");
        return -1;
    }
    
    printf("starting server...\n");
    
    // infinite loop, to end this server send SIGTERM. (CTRL+C)
    while (1) {
        libwebsocket_service(context, 50);
        // libwebsocket_service will process all waiting events with their
        // callback functions and then wait 50 ms.
        // (this is a single threaded webserver and this will keep our server
        // from generating load while there are not requests to process)
    }
    
    libwebsocket_context_destroy(context);
    
    return 0;
 }
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8">
	<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
	<script type="text/javascript">
	$(function() {
	window.WebSocket = window.WebSocket \|\| window.MozWebSocket;

	var websocket = new WebSocket('ws://127.0.0.1:9000',
	'dumb-increment-protocol');

	websocket.onopen = function () {
	$('h1').css('color', 'green');
	};

	websocket.onerror = function () {
	$('h1').css('color', 'red');
	};

	websocket.onmessage = function (message) {
	console.log(message.data);
	$('div').append($('<p>', { text: message.data }));
	};


	$('button').click(function(e) {
	e.preventDefault();
	websocket.send($('input').val());
	$('input').val('');
	});
	});
	</script>
	</head>
	<body>
	<h1>WebSockets test</h1>
	<form>
	<input type="text" />
	<button>Send</button>
	</form>
	<div></div>
	</body>
	</html>
	#include <stdio.h>
	#include <stdlib.h>
	#include <libwebsockets.h>


	static int callback_http(struct libwebsocket_context * this,
	struct libwebsocket *wsi,
	enum libwebsocket_callback_reasons reason, void *user,
	void *in, size_t len)
	{
	return 0;
	}



	static int callback_dumb_increment(struct libwebsocket_context * this,
	struct libwebsocket *wsi,
	enum libwebsocket_callback_reasons reason,
	void user, void in, size_t len)
	{
	switch (reason) {
	case LWS_CALLBACK_ESTABLISHED: // just log message that someone is connecting
	printf("connection established\n");
	break;
	case LWS_CALLBACK_RECEIVE: { // the funny part
	// create a buffer to hold our response
	// it has to have some pre and post padding. You don't need to care
	// what comes there, libwebsockets will do everything for you. For more info see
	// http://git.warmcat.com/cgi-bin/cgit/libwebsockets/tree/lib/libwebsockets.h#n597
	unsigned char buf = (unsigned char) malloc(LWS_SEND_BUFFER_PRE_PADDING + len +
	LWS_SEND_BUFFER_POST_PADDING);

	int i;

	// pointer to `void *in` holds the incomming request
	// we're just going to put it in reverse order and put it in `buf` with
	// correct offset. `len` holds length of the request.
	for (i=0; i < len; i++) {
	buf[LWS_SEND_BUFFER_PRE_PADDING + (len - 1) - i ] = ((char *) in)[i];
	}

	// log what we recieved and what we're going to send as a response.
	// that disco syntax `%.*s` is used to print just a part of our buffer
	// http://stackoverflow.com/questions/5189071/print-part-of-char-array
	printf("received data: %s, replying: %.s\n", (char ) in, (int) len,
	buf + LWS_SEND_BUFFER_PRE_PADDING);

	// send response
	// just notice that we have to tell where exactly our response starts. That's
	// why there's `buf[LWS_SEND_BUFFER_PRE_PADDING]` and how long it is.
	// we know that our response has the same length as request because
	// it's the same message in reverse order.
	libwebsocket_write(wsi, &buf[LWS_SEND_BUFFER_PRE_PADDING], len, LWS_WRITE_TEXT);

	// release memory back into the wild
	free(buf);
	break;
	}
	default:
	break;
	}

	return 0;
	}



	static struct libwebsocket_protocols protocols[] = {
	/* first protocol must always be HTTP handler */
	{
	"http-only", // name
	callback_http, // callback
	0 // per_session_data_size
	},
	{
	"dumb-increment-protocol", // protocol name - very important!
	callback_dumb_increment, // callback
	0 // we don't use any per session data
	},
	{
	NULL, NULL, 0 /* End of list */
	}
	};

	int main(void) {
	// server url will be http://localhost:9000
	int port = 9000;
	const char *interface = NULL;
	struct libwebsocket_context *context;
	// we're not using ssl
	const char *cert_path = NULL;
	const char *key_path = NULL;
	// no special options
	int opts = 0;

	// create libwebsocket context representing this server
	context = libwebsocket_create_context(port, interface, protocols,
	libwebsocket_internal_extensions,
	cert_path, key_path, -1, -1, opts);

	if (context == NULL) {
	fprintf(stderr, "libwebsocket init failed\n");
	return -1;
	}

	printf("starting server...\n");

	// infinite loop, to end this server send SIGTERM. (CTRL+C)
	while (1) {
	libwebsocket_service(context, 50);
	// libwebsocket_service will process all waiting events with their
	// callback functions and then wait 50 ms.
	// (this is a single threaded webserver and this will keep our server
	// from generating load while there are not requests to process)
	}

	libwebsocket_context_destroy(context);

	return 0;
	}