minimal-examples/ws-client/minimal-ws-client/minimal-ws-client.c

/*
 * lws-minimal-ws-client
 *
 * Written in 2010-2020 by Andy Green <andy@warmcat.com>
 *
 * This file is made available under the Creative Commons CC0 1.0
 * Universal Public Domain Dedication.
 *
 * This demonstrates a ws client that connects by default to libwebsockets.org
 * dumb increment ws server.
 */

#include <libwebsockets.h>
#include <string.h>
#include <signal.h>

/*
 * This represents your object that "contains" the client connection and has
 * the client connection bound to it
 */

static struct my_conn {
	lws_sorted_usec_list_t	sul;	     /* schedule connection retry */
	struct lws		*wsi;	     /* related wsi if any */
	uint16_t		retry_count; /* count of consequetive retries */
} mco;

static struct lws_context *context;
static int interrupted, port = 443, ssl_connection = LCCSCF_USE_SSL;
static const char *server_address = "libwebsockets.org",
		  *pro = "dumb-increment-protocol";

/*
 * The retry and backoff policy we want to use for our client connections
 */

static const uint32_t backoff_ms[] = { 1000, 2000, 3000, 4000, 5000 };

static const lws_retry_bo_t retry = {
	.retry_ms_table			= backoff_ms,
	.retry_ms_table_count		= LWS_ARRAY_SIZE(backoff_ms),
	.conceal_count			= LWS_ARRAY_SIZE(backoff_ms),

	.secs_since_valid_ping		= 3,  /* force PINGs after secs idle */
	.secs_since_valid_hangup	= 10, /* hangup after secs idle */

	.jitter_percent			= 20,
};

/*
 * Scheduled sul callback that starts the connection attempt
 */

static void
connect_client(lws_sorted_usec_list_t *sul)
{
	struct my_conn *mco = lws_container_of(sul, struct my_conn, sul);
	struct lws_client_connect_info i;

	memset(&i, 0, sizeof(i));

	i.context = context;
	i.port = port;
	i.address = server_address;
	i.path = "/";
	i.host = i.address;
	i.origin = i.address;
	i.ssl_connection = ssl_connection;
	i.protocol = pro;
	i.local_protocol_name = "lws-minimal-client";
	i.pwsi = &mco->wsi;
	i.retry_and_idle_policy = &retry;
	i.userdata = mco;

	if (!lws_client_connect_via_info(&i))
		/*
		 * Failed... schedule a retry... we can't use the _retry_wsi()
		 * convenience wrapper api here because no valid wsi at this
		 * point.
		 */
		if (lws_retry_sul_schedule(context, 0, sul, &retry,
					   connect_client, &mco->retry_count)) {
			lwsl_err("%s: connection attempts exhausted\n", __func__);
			interrupted = 1;
		}
}

static int
callback_minimal(struct lws *wsi, enum lws_callback_reasons reason,
		 void *user, void *in, size_t len)
{
	struct my_conn *mco = (struct my_conn *)user;

	switch (reason) {

	case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
		lwsl_err("CLIENT_CONNECTION_ERROR: %s\n",
			 in ? (char *)in : "(null)");
		goto do_retry;
		break;

	case LWS_CALLBACK_CLIENT_RECEIVE:
		lwsl_hexdump_notice(in, len);
		break;

	case LWS_CALLBACK_CLIENT_ESTABLISHED:
		lwsl_user("%s: established\n", __func__);
		break;

	case LWS_CALLBACK_CLIENT_CLOSED:
		goto do_retry;

	default:
		break;
	}

	return lws_callback_http_dummy(wsi, reason, user, in, len);

do_retry:
	/*
	 * retry the connection to keep it nailed up
	 *
	 * For this example, we try to conceal any problem for one set of
	 * backoff retries and then exit the app.
	 *
	 * If you set retry.conceal_count to be larger than the number of
	 * elements in the backoff table, it will never give up and keep
	 * retrying at the last backoff delay plus the random jitter amount.
	 */
	if (lws_retry_sul_schedule_retry_wsi(wsi, &mco->sul, connect_client,
					     &mco->retry_count)) {
		lwsl_err("%s: connection attempts exhausted\n", __func__);
		interrupted = 1;
	}

	return 0;
}

static const struct lws_protocols protocols[] = {
	{ "lws-minimal-client", callback_minimal, 0, 0, 0, NULL, 0 },
	LWS_PROTOCOL_LIST_TERM
};

static void
sigint_handler(int sig)
{
	interrupted = 1;
}

int main(int argc, const char **argv)
{
	struct lws_context_creation_info info;
	const char *p;
	int n = 0;

	signal(SIGINT, sigint_handler);
	memset(&info, 0, sizeof info);
	lws_cmdline_option_handle_builtin(argc, argv, &info);

	lwsl_user("LWS minimal ws client\n");

	info.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
	info.port = CONTEXT_PORT_NO_LISTEN; /* we do not run any server */
	info.protocols = protocols;

#if defined(LWS_WITH_MBEDTLS) || defined(USE_WOLFSSL)
	/*
	 * OpenSSL uses the system trust store.  mbedTLS has to be told which
	 * CA to trust explicitly.
	 */
	info.client_ssl_ca_filepath = "./libwebsockets.org.cer";
#endif

	if ((p = lws_cmdline_option(argc, argv, "--protocol")))
		pro = p;

	if ((p = lws_cmdline_option(argc, argv, "-s")))
		server_address = p;

	if ((p = lws_cmdline_option(argc, argv, "-p")))
		port = atoi(p);

	if (lws_cmdline_option(argc, argv, "-n"))
		ssl_connection &= ~LCCSCF_USE_SSL;

	if (lws_cmdline_option(argc, argv, "-j"))
		ssl_connection |= LCCSCF_ALLOW_SELFSIGNED;

	if (lws_cmdline_option(argc, argv, "-k"))
		ssl_connection |= LCCSCF_ALLOW_INSECURE;

	if (lws_cmdline_option(argc, argv, "-m"))
		ssl_connection |= LCCSCF_SKIP_SERVER_CERT_HOSTNAME_CHECK;

	if (lws_cmdline_option(argc, argv, "-e"))
		ssl_connection |= LCCSCF_ALLOW_EXPIRED;

	info.fd_limit_per_thread = 1 + 1 + 1;

	context = lws_create_context(&info);
	if (!context) {
		lwsl_err("lws init failed\n");
		return 1;
	}

	/* schedule the first client connection attempt to happen immediately */
	lws_sul_schedule(context, 0, &mco.sul, connect_client, 1);

	while (n >= 0 && !interrupted)
		n = lws_service(context, 0);

	lws_context_destroy(context);
	lwsl_user("Completed\n");

	return 0;
}