[Libwebsockets] a bug?

"Andy Green (林安廸)" andy at warmcat.com
Sat Mar 30 04:15:01 CET 2013


On 25/03/13 22:47, the mail apparently from klervi - Alex Rhatushnyak 
included:
> Hi Andy!
> Without '-u', just
> ./libwebsockets-test-server
> and
> ./libwebsockets-test-client localhost
> I observe the following after less than 5 minutes:
> on the server side:
>  > [1364221837:7220] PARSER: written 55 bytes to client
>  > [1364221837:7225] PARSER: written 55 bytes to client
>  > [1364221837:7229] PARSER: written 55 bytes to client
> ...
> on the client side:
> "rx 8190  rx 8190  rx 8190 ..."
> Until you stop one of them.
> Looks like server only sends and client only receives messages.
>
> With '-u', that is
> ./libwebsockets-test-client localhost -u
> the same "rx 8190  rx ..." pattern after less than 5 minutes on the
> client side,
> and similarly on the server side:
> [1364222548:0620] PARSER: written 8194 bytes to client
> [1364222548:0624] PARSER: written 8194 bytes to client
> [1364222548:0628] PARSER: written 8194 bytes to client
> ...
>
> OS X 10.8.2.
> Please find the updated test-server.c and test-client.c attached.
> Regards,
> Alex
>

As I mentioned last week, relying on the OS to buffer large atomic 
packets is not a good proposition, instead you need to make use of the 
websocket protocol fragmentation.

Attached are your demo programs rewritten to use fragmentation.

Now they can send and receive 8190-size packets with a 1024 (or other) 
fragment size and corresponding rx buffer; we only ask the OS to buffer 
1024 size packet for TX which is reasonable even on small embedded systems.

Do you see any problems with these on OSX?

-Andy
-------------- next part --------------
/*
 * libwebsockets-test-client - libwebsockets test implementation
 *
 * Copyright (C) 2011 Andy Green <andy at warmcat.com>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation:
 *  version 2.1 of the License.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA  02110-1301  USA
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <string.h>
#include <signal.h>

#ifdef CMAKE_BUILD
#include "lws_config.h"
#endif

#include <libwebsockets.h>

static unsigned int opts;
static int was_closed;
static int deny_deflate;
static int deny_mux;
static struct libwebsocket *wsi_mirror;
static int mirror_lifetime = 0;
static int force_exit = 0;

/*
 * This demo shows how to connect multiple websockets simultaneously to a
 * websocket server (there is no restriction on their having to be the same
 * server just it simplifies the demo).
 *
 *  dumb-increment-protocol:  we connect to the server and print the number
 *				we are given
 *
 *  lws-mirror-protocol: draws random circles, which are mirrored on to every
 *				client (see them being drawn in every browser
 *				session also using the test server)
 */

enum demo_protocols {

	PROTOCOL_DUMB_INCREMENT,
	PROTOCOL_LWS_MIRROR,

	/* always last */
	DEMO_PROTOCOL_COUNT
};


/* dumb_increment protocol */

struct lws_dumb_instance {
	char marshalling[16384];
	int marshalled;
};

static int
callback_dumb_increment(struct libwebsocket_context *this,
			struct libwebsocket *wsi,
			enum libwebsocket_callback_reasons reason,
					       void *user, void *in, size_t len)
{
	struct lws_dumb_instance *ldi = user;
	int i;

	switch (reason) {

	case LWS_CALLBACK_CLIENT_ESTABLISHED:
		ldi->marshalled = 0;
		break;

	case LWS_CALLBACK_CLOSED:
		fprintf(stderr, "LWS_CALLBACK_CLOSED\n");
		was_closed = 1;
		break;

	case LWS_CALLBACK_CLIENT_RECEIVE:
		//lwsl_notice("rx %d on %d\n", (int)len, ldi->marshalled);


		if (ldi->marshalled + len > sizeof ldi->marshalling) {
			lwsl_err("too large, closing\n");
			return -1;
		}
		memcpy(ldi->marshalling + ldi->marshalled, in, len);
		ldi->marshalled += len;

		if (!libwebsocket_is_final_fragment(wsi))
			break;

		fprintf(stderr, "final rx %d\n", ldi->marshalled);
		for (i = 0; i < ldi->marshalled; i++)
			if (ldi->marshalling[i] != 'a')
				break;

		if (i != 8190) {
			fprintf(stderr, "ERROR!!! Only the first %d of %d "
				"bytes are 'a'.  The remainder:\n",
							   i, ldi->marshalled);
			for (; i < len; i++)
				fprintf(stderr, "0x%X ", ldi->marshalling[i]);
			exit(1);
		}

		ldi->marshalled = 0;

		break;

	/* because we are protocols[0] ... */

	case LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED:
		if ((memcmp(in, "deflate", 7) == 0) && deny_deflate) {
			fprintf(stderr, "denied deflate extension\n");
			return 1;
		}
		if ((strcmp(in, "deflate-frame") == 0) && deny_deflate) {
			fprintf(stderr, "denied deflate-frame extension\n");
			return 1;
		}
		if ((strcmp(in, "x-google-mux") == 0) && deny_mux) {
			fprintf(stderr, "denied x-google-mux extension\n");
			return 1;
		}

		break;

	default:
		break;
	}

	return 0;
}


/* lws-mirror_protocol */


static int
callback_lws_mirror(struct libwebsocket_context *context,
			struct libwebsocket *wsi,
			enum libwebsocket_callback_reasons reason,
					       void *user, void *in, size_t len)
{
	unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 4096 +
						  LWS_SEND_BUFFER_POST_PADDING];
	int l = 0;
	int n;

	switch (reason) {

	case LWS_CALLBACK_CLOSED:
		fprintf(stderr, "mirror: LWS_CALLBACK_CLOSED mirror_lifetime=%d\n", mirror_lifetime);
		wsi_mirror = NULL;
		break;

	case LWS_CALLBACK_CLIENT_ESTABLISHED:

		/*
		 * start the ball rolling,
		 * LWS_CALLBACK_CLIENT_WRITEABLE will come next service
		 */

		libwebsocket_callback_on_writable(context, wsi);
		break;

	case LWS_CALLBACK_CLIENT_RECEIVE:
/*		fprintf(stderr, "rx %d '%s'\n", (int)len, (char *)in); */
		break;

	case LWS_CALLBACK_CLIENT_WRITEABLE:

		for (n = 0; n < 1; n++)
			l += sprintf((char *)&buf[LWS_SEND_BUFFER_PRE_PADDING + l],
					"c #%06X %d %d %d;",
					(int)random() & 0xffffff,
					(int)random() % 500,
					(int)random() % 250,
					(int)random() % 24);

		n = libwebsocket_write(wsi,
		   &buf[LWS_SEND_BUFFER_PRE_PADDING], l, opts | LWS_WRITE_TEXT);

		if (n < 0)
			return -1;
		if (n < l) {
			lwsl_err("Partial write LWS_CALLBACK_CLIENT_WRITEABLE\n");
			return -1;
		}

		mirror_lifetime--;
		if (!mirror_lifetime) {
			fprintf(stderr, "closing mirror session\n");
			return -1;
		} else
			/* get notified as soon as we can write again */
			libwebsocket_callback_on_writable(context, wsi);
		break;

	default:
		break;
	}

	return 0;
}


/* list of supported protocols and callbacks */

static struct libwebsocket_protocols protocols[] = {
	{
		"dumb-increment-protocol",
		callback_dumb_increment,
		sizeof(struct lws_dumb_instance),
		1024,
	},
	{
		"lws-mirror-protocol",
		callback_lws_mirror,
		0,
		128,
	},
	{ NULL, NULL, 0, 0 } /* end */
};

void sighandler(int sig)
{
	force_exit = 1;
}

static struct option options[] = {
	{ "help",	no_argument,		NULL, 'h' },
	{ "debug",      required_argument,      NULL, 'd' },
	{ "port",	required_argument,	NULL, 'p' },
	{ "ssl",	no_argument,		NULL, 's' },
	{ "version",	required_argument,	NULL, 'v' },
	{ "undeflated",	no_argument,		NULL, 'u' },
	{ "nomux",	no_argument,		NULL, 'n' },
	{ "longlived",	no_argument,		NULL, 'l' },
	{ NULL, 0, 0, 0 }
};


int main(int argc, char **argv)
{
	int n = 0;
	int ret = 0;
	int port = 7681;
	int use_ssl = 0;
	struct libwebsocket_context *context;
	const char *address;
	struct libwebsocket *wsi_dumb;
	int ietf_version = -1; /* latest */
	int longlived = 0;
	struct lws_context_creation_info info;

	memset(&info, 0, sizeof info);
	lws_set_log_level(7, NULL); // (1<<LLL_COUNT)-1, NULL);
	fprintf(stderr, "libwebsockets test client\n"
			"(C) Copyright 2010-2013 Andy Green <andy at warmcat.com> "
						    "licensed under LGPL2.1\n");

	if (argc < 2)
		goto usage;

	while (n >= 0) {
		n = getopt_long(argc, argv, "nuv:hsp:d:l", options, NULL);
		if (n < 0)
			continue;
		switch (n) {
		case 'd':
			lws_set_log_level(atoi(optarg), NULL);
			break;
		case 's':
			use_ssl = 2; /* 2 = allow selfsigned */
			break;
		case 'p':
			port = atoi(optarg);
			break;
		case 'l':
			longlived = 1;
			break;
		case 'v':
			ietf_version = atoi(optarg);
			break;
		case 'u':
			deny_deflate = 1;
			break;
		case 'n':
			deny_mux = 1;
			break;
		case 'h':
			goto usage;
		}
	}

	if (optind >= argc)
		goto usage;

	signal(SIGINT, sighandler);

	address = argv[optind];

	/*
	 * create the websockets context.  This tracks open connections and
	 * knows how to route any traffic and which protocol version to use,
	 * and if each connection is client or server side.
	 *
	 * For this client-only demo, we tell it to not listen on any port.
	 */

	info.port = CONTEXT_PORT_NO_LISTEN;
	info.protocols = protocols;
#ifndef LWS_NO_EXTENSIONS
	info.extensions = libwebsocket_get_internal_extensions();
#endif
	info.gid = -1;
	info.uid = -1;

	context = libwebsocket_create_context(&info);
	if (context == NULL) {
		fprintf(stderr, "Creating libwebsocket context failed\n");
		return 1;
	}

	/* create a client websocket using dumb increment protocol */

	wsi_dumb = libwebsocket_client_connect(context, address, port, use_ssl,
			"/", argv[optind], argv[optind],
			 protocols[PROTOCOL_DUMB_INCREMENT].name, ietf_version);

	if (wsi_dumb == NULL) {
		fprintf(stderr, "libwebsocket dumb connect failed\n");
		ret = 1;
		goto bail;
	}

	fprintf(stderr, "Websocket connections opened\n");

	/*
	 * sit there servicing the websocket context to handle incoming
	 * packets, and drawing random circles on the mirror protocol websocket
	 */

	n = 0;
	while (n >= 0 && !was_closed && !force_exit) {
		n = libwebsocket_service(context, 10);

		if (n < 0)
			continue;

		if (wsi_mirror)
			continue;

		/* create a client websocket using mirror protocol */

		wsi_mirror = libwebsocket_client_connect(context,
			address, port, use_ssl,  "/",
			argv[optind], argv[optind],
			protocols[PROTOCOL_LWS_MIRROR].name, ietf_version);

		if (wsi_mirror == NULL) {
			fprintf(stderr, "libwebsocket "
					      "dumb connect failed\n");
			ret = 1;
			goto bail;
		}

		mirror_lifetime = 10 + (random() & 1023);
		/* useful to test single connection stability */
		if (longlived)
			mirror_lifetime += 50000;

		fprintf(stderr, "opened mirror connection with "
				     "%d lifetime\n", mirror_lifetime);

		/*
		 * mirror_lifetime is decremented each send, when it reaches
		 * zero the connection is closed in the send callback.
		 * When the close callback comes, wsi_mirror is set to NULL
		 * so a new connection will be opened
		 */
	}

bail:
	fprintf(stderr, "Exiting\n");

	libwebsocket_context_destroy(context);

	return ret;

usage:
	fprintf(stderr, "Usage: libwebsockets-test-client "
				"<server address> [--port=<p>] "
				"[--ssl] [-k] [-v <ver>] "
				"[-d <log bitfield>] [-l]\n");
	return 1;
}
-------------- next part --------------
/*
 * libwebsockets-test-server - libwebsockets test implementation
 *
 * Copyright (C) 2010-2011 Andy Green <andy at warmcat.com>
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation:
 *  version 2.1 of the License.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 *  MA  02110-1301  USA
 */
#ifdef CMAKE_BUILD
#include "lws_config.h"
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <string.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <assert.h>
#ifdef WIN32

#ifdef EXTERNAL_POLL
	#ifndef WIN32_LEAN_AND_MEAN
	#define WIN32_LEAN_AND_MEAN
	#endif
	#include <winsock2.h>
	#include <ws2tcpip.h>
	#include <stddef.h>

	#include "websock-w32.h"
#endif

#else // NOT WIN32
#include <syslog.h>
#endif

#include <signal.h>

#include <libwebsockets.h>

static int close_testing;
int max_poll_elements;

struct pollfd *pollfds;
int *fd_lookup;
int count_pollfds;
int force_exit = 0;

/*
 * This demo server shows how to use libwebsockets for one or more
 * websocket protocols in the same server
 *
 * It defines the following websocket protocols:
 *
 *  dumb-increment-protocol:  once the socket is opened, an incrementing
 *				ascii string is sent down it every 50ms.
 *				If you send "reset\n" on the websocket, then
 *				the incrementing number is reset to 0.
 *
 *  lws-mirror-protocol: copies any received packet to every connection also
 *				using this protocol, including the sender
 */

enum demo_protocols {
	/* always first */
	PROTOCOL_HTTP = 0,

	PROTOCOL_DUMB_INCREMENT,
	PROTOCOL_LWS_MIRROR,

	/* always last */
	DEMO_PROTOCOL_COUNT
};


#define LOCAL_RESOURCE_PATH INSTALL_DATADIR"/libwebsockets-test-server"
char *resource_path = LOCAL_RESOURCE_PATH;

/*
 * We take a strict whitelist approach to stop ../ attacks
 */

struct serveable {
	const char *urlpath;
	const char *mimetype;
}; 

static const struct serveable whitelist[] = {
	{ "/favicon.ico", "image/x-icon" },
	{ "/libwebsockets.org-logo.png", "image/png" },

	/* last one is the default served if no match */
	{ "/test.html", "text/html" },
};

struct per_session_data__http {
	int fd;
};

/* this protocol server (always the first one) just knows how to do HTTP */

static int callback_http(struct libwebsocket_context *context,
		struct libwebsocket *wsi,
		enum libwebsocket_callback_reasons reason, void *user,
							   void *in, size_t len)
{
#if 0
	char client_name[128];
	char client_ip[128];
#endif
	char buf[256];
	int n, m;
	unsigned char *p;
	static unsigned char buffer[4096];
	struct stat stat_buf;
	struct per_session_data__http *pss = (struct per_session_data__http *)user;
#ifdef EXTERNAL_POLL
	int fd = (int)(long)in;
#endif

	switch (reason) {
	case LWS_CALLBACK_HTTP:

		/* check for the "send a big file by hand" example case */

		if (!strcmp((const char *)in, "/leaf.jpg")) {
			char leaf_path[1024];
			snprintf(leaf_path, sizeof(leaf_path), "%s/leaf.jpg", resource_path);

			/* well, let's demonstrate how to send the hard way */

			p = buffer;

#ifdef WIN32
			pss->fd = open(leaf_path, O_RDONLY | _O_BINARY);
#else
			pss->fd = open(leaf_path, O_RDONLY);
#endif

			if (pss->fd < 0)
				return -1;

			fstat(pss->fd, &stat_buf);

			/*
			 * we will send a big jpeg file, but it could be
			 * anything.  Set the Content-Type: appropriately
			 * so the browser knows what to do with it.
			 */

			p += sprintf((char *)p,
				"HTTP/1.0 200 OK\x0d\x0a"
				"Server: libwebsockets\x0d\x0a"
				"Content-Type: image/jpeg\x0d\x0a"
					"Content-Length: %u\x0d\x0a\x0d\x0a",
					(unsigned int)stat_buf.st_size);

			/*
			 * send the http headers...
			 * this won't block since it's the first payload sent
			 * on the connection since it was established
			 * (too small for partial)
			 */

			n = libwebsocket_write(wsi, buffer,
				   p - buffer, LWS_WRITE_HTTP);

			if (n < 0) {
				close(pss->fd);
				return -1;
			}
			/*
			 * book us a LWS_CALLBACK_HTTP_WRITEABLE callback
			 */
			libwebsocket_callback_on_writable(context, wsi);
			break;
		}

		/* if not, send a file the easy way */

		for (n = 0; n < (sizeof(whitelist) / sizeof(whitelist[0]) - 1); n++)
			if (in && strcmp((const char *)in, whitelist[n].urlpath) == 0)
				break;

		sprintf(buf, "%s%s", resource_path, whitelist[n].urlpath);

		if (libwebsockets_serve_http_file(context, wsi, buf, whitelist[n].mimetype))
			return -1; /* through completion or error, close the socket */

		/*
		 * notice that the sending of the file completes asynchronously,
		 * we'll get a LWS_CALLBACK_HTTP_FILE_COMPLETION callback when
		 * it's done
		 */

		break;

	case LWS_CALLBACK_HTTP_FILE_COMPLETION:
//		lwsl_info("LWS_CALLBACK_HTTP_FILE_COMPLETION seen\n");
		/* kill the connection after we sent one file */
		return -1;

	case LWS_CALLBACK_HTTP_WRITEABLE:
		/*
		 * we can send more of whatever it is we were sending
		 */

		do {
			n = read(pss->fd, buffer, sizeof buffer);
			/* problem reading, close conn */
			if (n < 0)
				goto bail;
			/* sent it all, close conn */
			if (n == 0)
				goto bail;
			/*
			 * because it's HTTP and not websocket, don't need to take
			 * care about pre and postamble
			 */
			m = libwebsocket_write(wsi, buffer, n, LWS_WRITE_HTTP);
			if (m < 0)
				/* write failed, close conn */
				goto bail;
			if (m != n)
				/* partial write, adjust */
				lseek(pss->fd, m - n, SEEK_CUR);

		} while (!lws_send_pipe_choked(wsi));
		libwebsocket_callback_on_writable(context, wsi);
		break;

bail:
		close(pss->fd);
		return -1;

	/*
	 * callback for confirming to continue with client IP appear in
	 * protocol 0 callback since no websocket protocol has been agreed
	 * yet.  You can just ignore this if you won't filter on client IP
	 * since the default uhandled callback return is 0 meaning let the
	 * connection continue.
	 */

	case LWS_CALLBACK_FILTER_NETWORK_CONNECTION:
#if 0
		libwebsockets_get_peer_addresses(context, wsi, (int)(long)in, client_name,
			     sizeof(client_name), client_ip, sizeof(client_ip));

		fprintf(stderr, "Received network connect from %s (%s)\n",
							client_name, client_ip);
#endif
		/* if we returned non-zero from here, we kill the connection */
		break;

#ifdef EXTERNAL_POLL
	/*
	 * callbacks for managing the external poll() array appear in
	 * protocol 0 callback
	 */

	case LWS_CALLBACK_ADD_POLL_FD:

		if (count_pollfds >= max_poll_elements) {
			lwsl_err("LWS_CALLBACK_ADD_POLL_FD: too many sockets to track\n");
			return 1;
		}

		fd_lookup[fd] = count_pollfds;
		pollfds[count_pollfds].fd = fd;
		pollfds[count_pollfds].events = (int)(long)len;
		pollfds[count_pollfds++].revents = 0;
		break;

	case LWS_CALLBACK_DEL_POLL_FD:
		if (!--count_pollfds)
			break;
		m = fd_lookup[fd];
		/* have the last guy take up the vacant slot */
		pollfds[m] = pollfds[count_pollfds];
		fd_lookup[pollfds[count_pollfds].fd] = m;
		break;

	case LWS_CALLBACK_SET_MODE_POLL_FD:
		pollfds[fd_lookup[fd]].events |= (int)(long)len;
		break;

	case LWS_CALLBACK_CLEAR_MODE_POLL_FD:
		pollfds[fd_lookup[fd]].events &= ~(int)(long)len;
		break;
#endif

	default:
		break;
	}

	return 0;
}

/*
 * this is just an example of parsing handshake headers, you don't need this
 * in your code unless you will filter allowing connections by the header
 * content
 */

static void
dump_handshake_info(struct libwebsocket *wsi)
{
	int n;
	static const char *token_names[WSI_TOKEN_COUNT] = {
		/*[WSI_TOKEN_GET_URI]		=*/ "GET URI",
		/*[WSI_TOKEN_HOST]		=*/ "Host",
		/*[WSI_TOKEN_CONNECTION]	=*/ "Connection",
		/*[WSI_TOKEN_KEY1]		=*/ "key 1",
		/*[WSI_TOKEN_KEY2]		=*/ "key 2",
		/*[WSI_TOKEN_PROTOCOL]		=*/ "Protocol",
		/*[WSI_TOKEN_UPGRADE]		=*/ "Upgrade",
		/*[WSI_TOKEN_ORIGIN]		=*/ "Origin",
		/*[WSI_TOKEN_DRAFT]		=*/ "Draft",
		/*[WSI_TOKEN_CHALLENGE]		=*/ "Challenge",

		/* new for 04 */
		/*[WSI_TOKEN_KEY]		=*/ "Key",
		/*[WSI_TOKEN_VERSION]		=*/ "Version",
		/*[WSI_TOKEN_SWORIGIN]		=*/ "Sworigin",

		/* new for 05 */
		/*[WSI_TOKEN_EXTENSIONS]	=*/ "Extensions",

		/* client receives these */
		/*[WSI_TOKEN_ACCEPT]		=*/ "Accept",
		/*[WSI_TOKEN_NONCE]		=*/ "Nonce",
		/*[WSI_TOKEN_HTTP]		=*/ "Http",
		/*[WSI_TOKEN_MUXURL]	=*/ "MuxURL",
	};
	char buf[256];

	for (n = 0; n < WSI_TOKEN_COUNT; n++) {
		if (!lws_hdr_total_length(wsi, n))
			continue;

		lws_hdr_copy(wsi, buf, sizeof buf, n);

		fprintf(stderr, "    %s = %s\n", token_names[n], buf);
	}
}

/* dumb_increment protocol */

/*
 * one of these is auto-created for each connection and a pointer to the
 * appropriate instance is passed to the callback in the user parameter
 *
 * for this example protocol we use it to individualize the count for each
 * connection.
 */

struct per_session_data__dumb_increment {
	int number;

	int issued;
};

static int
callback_dumb_increment(struct libwebsocket_context *context,
			struct libwebsocket *wsi,
			enum libwebsocket_callback_reasons reason,
					       void *user, void *in, size_t len)
{
	int n, m;
	unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 8192 +
						  LWS_SEND_BUFFER_POST_PADDING];
	unsigned char *p = &buf[LWS_SEND_BUFFER_PRE_PADDING];
	struct per_session_data__dumb_increment *pss = (struct per_session_data__dumb_increment *)user;
	int write_mode = LWS_WRITE_CONTINUATION;

	switch (reason) {

	case LWS_CALLBACK_ESTABLISHED:
		lwsl_info("callback_dumb_increment: "
						 "LWS_CALLBACK_ESTABLISHED\n");
		pss->number = 0;
		pss->issued = 0;
		break;

	case LWS_CALLBACK_SERVER_WRITEABLE:
		if (!pss->issued)
			write_mode = LWS_WRITE_TEXT;

		n = 1024;
		if (pss->issued + n >= 8190)
			n = 8190 - pss->issued;
		else
			write_mode |= LWS_WRITE_NO_FIN;

		memset(LWS_SEND_BUFFER_PRE_PADDING + buf, 'a', n);
		pss->issued += n;
		if (pss->issued == 8190)
			pss->issued = 0;
		m = libwebsocket_write(wsi, p, n, write_mode);
		if (m < n) {
			//lwsl_err("ERROR %d writing to di socket\n", n);
			lwsl_err("+++++++++++++++++++++++++ERROR %d (sent %d) writing to di socket\n", m, n);
			return -1;
		}
		if (close_testing && pss->number == 50) {
			lwsl_info("close tesing limit, closing\n");
			return -1;
		}
		break;

	case LWS_CALLBACK_RECEIVE:
//		fprintf(stderr, "rx %d\n", (int)len);
		if (len < 6)
			break;
		if (strcmp((const char *)in, "reset\n") == 0)
			pss->number = 0;
		break;
	/*
	 * this just demonstrates how to use the protocol filter. If you won't
	 * study and reject connections based on header content, you don't need
	 * to handle this callback
	 */

	case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
		dump_handshake_info(wsi);
		/* you could return non-zero here and kill the connection */
		break;

	default:
		break;
	}

	return 0;
}


/* lws-mirror_protocol */

#define MAX_MESSAGE_QUEUE 32

struct per_session_data__lws_mirror {
	struct libwebsocket *wsi;
	int ringbuffer_tail;
};

struct a_message {
	void *payload;
	size_t len;
};

static struct a_message ringbuffer[MAX_MESSAGE_QUEUE];
static int ringbuffer_head;

static int
callback_lws_mirror(struct libwebsocket_context *context,
			struct libwebsocket *wsi,
			enum libwebsocket_callback_reasons reason,
					       void *user, void *in, size_t len)
{
	int n;
	struct per_session_data__lws_mirror *pss = (struct per_session_data__lws_mirror *)user;

	switch (reason) {

	case LWS_CALLBACK_ESTABLISHED:
		lwsl_info("callback_lws_mirror: LWS_CALLBACK_ESTABLISHED\n");
		pss->ringbuffer_tail = ringbuffer_head;
		pss->wsi = wsi;
		break;

	case LWS_CALLBACK_PROTOCOL_DESTROY:
		lwsl_notice("mirror protocol cleaning up\n");
		for (n = 0; n < sizeof ringbuffer / sizeof ringbuffer[0]; n++)
			if (ringbuffer[n].payload)
				free(ringbuffer[n].payload);
		break;

	case LWS_CALLBACK_SERVER_WRITEABLE:
		if (close_testing)
			break;
		while (pss->ringbuffer_tail != ringbuffer_head) {

			n = libwebsocket_write(wsi, (unsigned char *)
				   ringbuffer[pss->ringbuffer_tail].payload +
				   LWS_SEND_BUFFER_PRE_PADDING,
				   ringbuffer[pss->ringbuffer_tail].len,
								LWS_WRITE_TEXT);
			if (n < ringbuffer[pss->ringbuffer_tail].len) {
				lwsl_err("ERROR %d writing to mirror socket\n", n);
				return -1;
			}
			if (n < ringbuffer[pss->ringbuffer_tail].len)
				lwsl_err("mirror partial write %d vs %d\n",
				       n, ringbuffer[pss->ringbuffer_tail].len);

			if (pss->ringbuffer_tail == (MAX_MESSAGE_QUEUE - 1))
				pss->ringbuffer_tail = 0;
			else
				pss->ringbuffer_tail++;

			if (((ringbuffer_head - pss->ringbuffer_tail) &
				  (MAX_MESSAGE_QUEUE - 1)) == (MAX_MESSAGE_QUEUE - 15))
				libwebsocket_rx_flow_allow_all_protocol(
					       libwebsockets_get_protocol(wsi));

			// lwsl_debug("tx fifo %d\n", (ringbuffer_head - pss->ringbuffer_tail) & (MAX_MESSAGE_QUEUE - 1));

			if (lws_send_pipe_choked(wsi)) {
				libwebsocket_callback_on_writable(context, wsi);
				break;
			}
			/*
			 * for tests with chrome on same machine as client and
			 * server, this is needed to stop chrome choking
			 */
			usleep(1);
		}
		break;

	case LWS_CALLBACK_RECEIVE:

		if (((ringbuffer_head - pss->ringbuffer_tail) &
				  (MAX_MESSAGE_QUEUE - 1)) == (MAX_MESSAGE_QUEUE - 1)) {
			lwsl_err("dropping!\n");
			goto choke;
		}

		if (ringbuffer[ringbuffer_head].payload)
			free(ringbuffer[ringbuffer_head].payload);

		ringbuffer[ringbuffer_head].payload =
				malloc(LWS_SEND_BUFFER_PRE_PADDING + len +
						  LWS_SEND_BUFFER_POST_PADDING);
		ringbuffer[ringbuffer_head].len = len;
		memcpy((char *)ringbuffer[ringbuffer_head].payload +
					  LWS_SEND_BUFFER_PRE_PADDING, in, len);
		if (ringbuffer_head == (MAX_MESSAGE_QUEUE - 1))
			ringbuffer_head = 0;
		else
			ringbuffer_head++;

		if (((ringbuffer_head - pss->ringbuffer_tail) &
				  (MAX_MESSAGE_QUEUE - 1)) != (MAX_MESSAGE_QUEUE - 2))
			goto done;

choke:
		lwsl_debug("LWS_CALLBACK_RECEIVE: throttling %p\n", wsi);
		libwebsocket_rx_flow_control(wsi, 0);

//		lwsl_debug("rx fifo %d\n", (ringbuffer_head - pss->ringbuffer_tail) & (MAX_MESSAGE_QUEUE - 1));
done:
		libwebsocket_callback_on_writable_all_protocol(
					       libwebsockets_get_protocol(wsi));
		break;

	/*
	 * this just demonstrates how to use the protocol filter. If you won't
	 * study and reject connections based on header content, you don't need
	 * to handle this callback
	 */

	case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
		dump_handshake_info(wsi);
		/* you could return non-zero here and kill the connection */
		break;

	default:
		break;
	}

	return 0;
}


/* list of supported protocols and callbacks */

static struct libwebsocket_protocols protocols[] = {
	/* first protocol must always be HTTP handler */

	{
		"http-only",		/* name */
		callback_http,		/* callback */
		sizeof (struct per_session_data__http),	/* per_session_data_size */
		0,			/* max frame size / rx buffer */
	},
	{
		"dumb-increment-protocol",
		callback_dumb_increment,
		sizeof(struct per_session_data__dumb_increment),
		16384,
	},
	{
		"lws-mirror-protocol",
		callback_lws_mirror,
		sizeof(struct per_session_data__lws_mirror),
		128,
	},
	{ NULL, NULL, 0, 0 } /* terminator */
};

void sighandler(int sig)
{
	force_exit = 1;
}

static struct option options[] = {
	{ "help",	no_argument,		NULL, 'h' },
	{ "debug",	required_argument,	NULL, 'd' },
	{ "port",	required_argument,	NULL, 'p' },
	{ "ssl",	no_argument,		NULL, 's' },
	{ "interface",  required_argument,	NULL, 'i' },
	{ "closetest",  no_argument,		NULL, 'c' },
#ifndef LWS_NO_DAEMONIZE
	{ "daemonize", 	no_argument,		NULL, 'D' },
#endif
	{ "resource_path", required_argument,		NULL, 'r' },
	{ NULL, 0, 0, 0 }
};

int main(int argc, char **argv)
{
	char cert_path[1024];
	char key_path[1024];
	int n = 0;
	int use_ssl = 0;
	struct libwebsocket_context *context;
	int opts = 0;
	char interface_name[128] = "";
	const char *iface = NULL;
#ifndef WIN32
	int syslog_options = LOG_PID | LOG_PERROR;
#endif
	unsigned int oldus = 0;
	struct lws_context_creation_info info;

	int debug_level = 7; // (1<<LLL_COUNT)-1;
#ifndef LWS_NO_DAEMONIZE
	int daemonize = 0;
#endif

	memset(&info, 0, sizeof info);
	info.port = 7681;

	while (n >= 0) {
		n = getopt_long(argc, argv, "ci:hsp:d:Dr:", options, NULL);
		if (n < 0)
			continue;
		switch (n) {
#ifndef LWS_NO_DAEMONIZE
		case 'D':
			daemonize = 1;
			#ifndef WIN32
			syslog_options &= ~LOG_PERROR;
			#endif
			break;
#endif
		case 'd':
			debug_level = atoi(optarg);
			break;
		case 's':
			use_ssl = 1;
			break;
		case 'p':
			info.port = atoi(optarg);
			break;
		case 'i':
			strncpy(interface_name, optarg, sizeof interface_name);
			interface_name[(sizeof interface_name) - 1] = '\0';
			iface = interface_name;
			break;
		case 'c':
			close_testing = 1;
			fprintf(stderr, " Close testing mode -- closes on "
					   "client after 50 dumb increments"
					   "and suppresses lws_mirror spam\n");
			break;
		case 'r':
			resource_path = optarg;
			printf("Setting resource path to \"%s\"\n", resource_path);
			break;
		case 'h':
			fprintf(stderr, "Usage: test-server "
					"[--port=<p>] [--ssl] "
					"[-d <log bitfield>] "
					"[--resource_path <path>]\n");
			exit(1);
		}
	}

#if !defined(LWS_NO_DAEMONIZE) && !defined(WIN32)
	/* 
	 * normally lock path would be /var/lock/lwsts or similar, to
	 * simplify getting started without having to take care about
	 * permissions or running as root, set to /tmp/.lwsts-lock
	 */
	if (daemonize && lws_daemonize("/tmp/.lwsts-lock")) {
		fprintf(stderr, "Failed to daemonize\n");
		return 1;
	}
#endif

	signal(SIGINT, sighandler);

#ifndef WIN32
	/* we will only try to log things according to our debug_level */
	setlogmask(LOG_UPTO (LOG_DEBUG));
	openlog("lwsts", syslog_options, LOG_DAEMON);
#endif

	/* tell the library what debug level to emit and to send it to syslog */
	lws_set_log_level(debug_level, NULL);

	lwsl_notice("libwebsockets test server - "
			"(C) Copyright 2010-2013 Andy Green <andy at warmcat.com> - "
						    "licensed under LGPL2.1\n");
#ifdef EXTERNAL_POLL
	max_poll_elements = getdtablesize();
	pollfds = malloc(max_poll_elements * sizeof (struct pollfd));
	fd_lookup = malloc(max_poll_elements * sizeof (int));
	if (pollfds == NULL || fd_lookup == NULL) {
		lwsl_err("Out of memory pollfds=%d\n", max_poll_elements);
		return -1;
	}
#endif

	info.iface = iface;
	info.protocols = protocols;
#ifndef LWS_NO_EXTENSIONS
	info.extensions = libwebsocket_get_internal_extensions();
#endif
	if (!use_ssl) {
		info.ssl_cert_filepath = NULL;
		info.ssl_private_key_filepath = NULL;
	} else {
		snprintf(cert_path, sizeof(cert_path), "%s/libwebsockets-test-server.pem", resource_path);
		snprintf(key_path, sizeof(cert_path), "%s/libwebsockets-test-server.key.pem", resource_path);

		info.ssl_cert_filepath = cert_path;
		info.ssl_private_key_filepath = key_path;
	}
	info.gid = -1;
	info.uid = -1;
	info.options = opts;

	context = libwebsocket_create_context(&info);
	if (context == NULL) {
		lwsl_err("libwebsocket init failed\n");
		return -1;
	}

	n = 0;
	while (n >= 0 && !force_exit) {
		struct timeval tv;

		gettimeofday(&tv, NULL);

		/*
		 * This provokes the LWS_CALLBACK_SERVER_WRITEABLE for every
		 * live websocket connection using the DUMB_INCREMENT protocol,
		 * as soon as it can take more packets (usually immediately)
		 */

		if (((unsigned int)tv.tv_usec - oldus) > 1) {
			libwebsocket_callback_on_writable_all_protocol(&protocols[PROTOCOL_DUMB_INCREMENT]);
			oldus = tv.tv_usec;
		}

#ifdef EXTERNAL_POLL

		/*
		 * this represents an existing server's single poll action
		 * which also includes libwebsocket sockets
		 */

		n = poll(pollfds, count_pollfds, 50);
		if (n < 0)
			continue;


		if (n)
			for (n = 0; n < count_pollfds; n++)
				if (pollfds[n].revents)
					/*
					* returns immediately if the fd does not
					* match anything under libwebsockets
					* control
					*/
					if (libwebsocket_service_fd(context,
								  &pollfds[n]) < 0)
						goto done;
#else
		/*
		 * If libwebsockets sockets are all we care about,
		 * you can use this api which takes care of the poll()
		 * and looping through finding who needed service.
		 *
		 * If no socket needs service, it'll return anyway after
		 * the number of ms in the second argument.
		 */

		n = libwebsocket_service(context, 50);
#endif
	}

#ifdef EXTERNAL_POLL
done:
#endif

	libwebsocket_context_destroy(context);

	lwsl_notice("libwebsockets-test-server exited cleanly\n");

#ifndef WIN32
	closelog();
#endif

	return 0;
}


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