minimal-ws-proxy

minimal-examples/minimal-ws-proxy/CMakeLists.txt

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+cmake_minimum_required(VERSION 2.8)
+
+set(SAMP lws-minimal-ws-proxy)
+set(SRCS minimal-ws-proxy.c)
+
+if (UNIX)
+      set(CMAKE_C_FLAGS "-Wall -Wsign-compare -Wignored-qualifiers -Wtype-limits -Wuninitialized -Werror -Wundef ${CMAKE_C_FLAGS}" )
+endif()
+
+add_executable(${SAMP} ${SRCS})
+target_link_libraries(${SAMP} -lwebsockets)

minimal-examples/minimal-ws-proxy/README.md

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+# lws minimal ws proxy
+
+## Build
+
+```
+ $ cmake . && make
+```
+
+## Description
+
+This is the same as minimal-ws-server-ring, but with the
+inclusion of a ws client connection to https://libwebsockets.org
+using the dumb-increment protocol feeding the ringbuffer.
+
+Each client that connect to this server receives the content that
+had arrived on the client connection feeding the ringbuffer proxied
+to their browser window over a ws connection.
+
+## Usage
+
+```
+ $ ./lws-minimal-ws-proxy 
+[2018/03/14 17:50:10:6938] USER: LWS minimal ws proxy | visit http://localhost:7681
+[2018/03/14 17:50:10:6955] NOTICE: Creating Vhost 'default' port 7681, 2 protocols, IPv6 off
+[2018/03/14 17:50:10:6955] NOTICE:  Using non-SSL mode
+[2018/03/14 17:50:10:7035] NOTICE: created client ssl context for default
+[2018/03/14 17:50:11:7047] NOTICE: binding to lws-minimal-proxy
+[2018/03/14 17:50:11:7047] NOTICE: lws_client_connect_2: 0x872e60: address libwebsockets.org
+[2018/03/14 17:50:12:3282] NOTICE: lws_client_connect_2: 0x872e60: address libwebsockets.org
+[2018/03/14 17:50:13:8195] USER: callback_minimal: established
+```
+
+Visit http://localhost:7681 on multiple browser windows
+
+Data received on the remote wss connection is copied to all open browser windows.
+
+A ringbuffer holds up to 8 lines of text in the server, and the browser shows
+the last 20 lines of received text.

minimal-examples/minimal-ws-proxy/minimal-ws-proxy.c

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+/*
+ * lws-minimal-ws-proxy
+ *
+ * Copyright (C) 2018 Andy Green <andy@warmcat.com>
+ *
+ * This file is made available under the Creative Commons CC0 1.0
+ * Universal Public Domain Dedication.
+ *
+ * This demonstrates the most minimal http server you can make with lws,
+ * with an added websocket proxy distributing what is received on a
+ * dumb-increment wss connection to https://libwebsockets.org to all
+ * browsers connected to this server.
+ *
+ * To keep it simple, it serves stuff in the subdirectory "./mount-origin" of
+ * the directory it was started in.
+ * You can change that by changing mount.origin.
+ */
+
+#include <libwebsockets.h>
+#include <string.h>
+#include <signal.h>
+
+#define LWS_PLUGIN_STATIC
+#include "protocol_lws_minimal.c"
+
+static struct lws_protocols protocols[] = {
+	{ "http", lws_callback_http_dummy, 0, 0 },
+	LWS_PLUGIN_PROTOCOL_MINIMAL,
+	{ NULL, NULL, 0, 0 } /* terminator */
+};
+
+static int interrupted;
+
+static const struct lws_http_mount mount = {
+	/* .mount_next */		NULL,		/* linked-list "next" */
+	/* .mountpoint */		"/",		/* mountpoint URL */
+	/* .origin */			"./mount-origin", /* serve from dir */
+	/* .def */			"index.html",	/* default filename */
+	/* .protocol */			NULL,
+	/* .cgienv */			NULL,
+	/* .extra_mimetypes */		NULL,
+	/* .interpret */		NULL,
+	/* .cgi_timeout */		0,
+	/* .cache_max_age */		0,
+	/* .auth_mask */		0,
+	/* .cache_reusable */		0,
+	/* .cache_revalidate */		0,
+	/* .cache_intermediaries */	0,
+	/* .origin_protocol */		LWSMPRO_FILE,	/* files in a dir */
+	/* .mountpoint_len */		1,		/* char count */
+	/* .basic_auth_login_file */	NULL,
+};
+
+void sigint_handler(int sig)
+{
+	interrupted = 1;
+}
+
+int main(int argc, char **argv)
+{
+	struct lws_context_creation_info info;
+	struct lws_context *context;
+	int n = 0;
+
+	signal(SIGINT, sigint_handler);
+
+	memset(&info, 0, sizeof info); /* otherwise uninitialized garbage */
+	info.options = LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
+	info.port = 7681;
+	info.mounts = &mount;
+	info.protocols = protocols;
+
+	lws_set_log_level(LLL_ERR | LLL_WARN | LLL_NOTICE | LLL_USER
+			/* | LLL_INFO */ /* | LLL_DEBUG */, NULL);
+
+	lwsl_user("LWS minimal ws proxy | visit http://localhost:7681\n");
+
+	context = lws_create_context(&info);
+	if (!context) {
+		lwsl_err("lws init failed\n");
+		return 1;
+	}
+
+	while (n >= 0 && !interrupted)
+		n = lws_service(context, 1000);
+
+	lws_context_destroy(context);
+
+	return 0;
+}

minimal-examples/minimal-ws-proxy/mount-origin/index.html

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+<meta charset="UTF-8"> 
+<html>
+	<body>
+		<img src="libwebsockets.org-logo.png"><br>
+	
+		<b>Minimal ws server proxy example</b>.<br>
+		The server makes a dumb-increment-protocol wss connection<br>
+		to libwebsockets.org.  It proxies what it was sent to<br>
+		all browsers open on this page.<br>
+		The textarea show the last 20 lines received.
+		<br>
+		<br>
+		<textarea id=r readonly cols=40 rows=20></textarea><br>
+	</body>
+	
+	
+<script>
+
+var head = 0, tail = 0, ring = new Array();
+
+function get_appropriate_ws_url(extra_url)
+{
+	var pcol;
+	var u = document.URL;
+
+	/*
+	 * We open the websocket encrypted if this page came on an
+	 * https:// url itself, otherwise unencrypted
+	 */
+
+	if (u.substring(0, 5) == "https") {
+		pcol = "wss://";
+		u = u.substr(8);
+	} else {
+		pcol = "ws://";
+		if (u.substring(0, 4) == "http")
+			u = u.substr(7);
+	}
+
+	u = u.split('/');
+
+	/* + "/xxx" bit is for IE10 workaround */
+
+	return pcol + u[0] + "/" + extra_url;
+}
+
+function new_ws(urlpath, protocol)
+{
+	if (typeof MozWebSocket != "undefined")
+		return new MozWebSocket(urlpath, protocol);
+
+	return new WebSocket(urlpath, protocol);
+}
+
+ws = new_ws(get_appropriate_ws_url(""), "lws-minimal-proxy");
+try {
+	ws.onopen = function() {
+		document.getElementById("m").disabled = 0;
+		document.getElementById("b").disabled = 0;
+	} 
+
+	ws.onmessage =function got_packet(msg) {
+		var n, s = "";
+
+		ring[head] = msg.data + "\n";
+		head = (head + 1) % 20;
+		if (tail == head)
+			tail = (tail + 1) % 20;
+
+		n = tail;
+		do {
+			s = s + ring[n];
+			n = (n + 1) % 20;
+		} while (n != head);
+
+		document.getElementById("r").value = s; 
+		document.getElementById("r").scrollTop =
+			document.getElementById("r").scrollHeight;
+	} 
+
+	ws.onclose = function(){
+		document.getElementById("m").disabled = 1;
+		document.getElementById("b").disabled = 1;
+	}
+} catch(exception) {
+	alert('<p>Error' + exception);  
+}
+
+</script>
+</html>
+

minimal-examples/minimal-ws-proxy/protocol_lws_minimal.c

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+/*
+ * ws protocol handler plugin for "lws-minimal"
+ *
+ * Copyright (C) 2010-2018 Andy Green <andy@warmcat.com>
+ *
+ * This file is made available under the Creative Commons CC0 1.0
+ * Universal Public Domain Dedication.
+ *
+ * This version uses an lws_ring ringbuffer to cache up to 8 messages at a time,
+ * so it's not so easy to lose messages.
+ */
+
+#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;
+	uint32_t tail;
+};
+
+/* 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 lws_ring *ring; /* ringbuffer holding unsent messages */
+	struct lws_client_connect_info i;
+	struct lws *client_wsi;
+};
+
+/* 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
+connect_client(struct per_vhost_data__minimal *vhd)
+{
+	vhd->i.context = vhd->context;
+	vhd->i.port = 443;
+	vhd->i.address = "libwebsockets.org";
+	vhd->i.path = "/";
+	vhd->i.host = vhd->i.address;
+	vhd->i.origin = vhd->i.address;
+	vhd->i.ssl_connection = 1;
+
+	vhd->i.protocol = "dumb-increment-protocol";
+	vhd->i.local_protocol_name = "lws-minimal-proxy";
+	vhd->i.pwsi = &vhd->client_wsi;
+
+	return !lws_client_connect_via_info(&vhd->i);
+}
+
+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));
+	const struct msg *pmsg;
+	struct msg amsg;
+	uint32_t oldest;
+	int n, m;
+
+	switch (reason) {
+
+	/* --- protocol lifecycle callbacks --- */
+
+	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);
+
+		vhd->ring = lws_ring_create(sizeof(struct msg), 8,
+					    __minimal_destroy_message);
+		if (connect_client(vhd))
+			lws_timed_callback_vh_protocol(vhd->vhost,
+						vhd->protocol,
+					        LWS_CALLBACK_USER, 1);
+		break;
+
+	case LWS_CALLBACK_PROTOCOL_DESTROY:
+		lws_ring_destroy(vhd->ring);
+		break;
+
+	/* --- serving callbacks --- */
+
+	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->tail = lws_ring_get_oldest_tail(vhd->ring);
+		pss->wsi = wsi;
+		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:
+		pmsg = lws_ring_get_element(vhd->ring, &pss->tail);
+		if (!pmsg)
+			break;
+
+		/* notice we allowed for LWS_PRE in the payload already */
+		m = lws_write(wsi, pmsg->payload + LWS_PRE, pmsg->len,
+			      LWS_WRITE_TEXT);
+		if (m < (int)pmsg->len) {
+			lwsl_err("ERROR %d writing to di socket\n", n);
+			return -1;
+		}
+
+		n = lws_ring_get_oldest_tail(vhd->ring) == pss->tail;
+		lws_ring_consume(vhd->ring, &pss->tail, NULL, 1);
+
+		if (n) { /* we may have been the oldest tail */
+			n = 0;
+			oldest = pss->tail;
+			lws_start_foreach_llp(
+					struct per_session_data__minimal **,
+					ppss, vhd->pss_list) {
+				m = lws_ring_get_count_waiting_elements(
+						vhd->ring, &(*ppss)->tail);
+				if (m > n) {
+					n = m;
+					oldest = (*ppss)->tail;
+				}
+			} lws_end_foreach_llp(ppss, pss_list);
+
+			/* this will delete any entries behind the new oldest */
+			lws_ring_update_oldest_tail(vhd->ring, oldest);
+		}
+
+		/* more to do? */
+		if (lws_ring_get_element(vhd->ring, &pss->tail))
+			/* come back as soon as we can write more */
+			lws_callback_on_writable(pss->wsi);
+		break;
+
+	/* --- client callbacks --- */
+
+	case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
+		lwsl_err("CLIENT_CONNECTION_ERROR: %s\n",
+			 in ? (char *)in : "(null)");
+		vhd->client_wsi = NULL;
+		lws_timed_callback_vh_protocol(vhd->vhost, vhd->protocol,
+					       LWS_CALLBACK_USER, 1);
+		break;
+
+	case LWS_CALLBACK_CLIENT_ESTABLISHED:
+		lwsl_user("%s: established\n", __func__);
+		break;
+
+	case LWS_CALLBACK_CLIENT_RECEIVE:
+		/* if no clients, just drop incoming */
+		if (!vhd->pss_list)
+			break;
+
+		n = (int)lws_ring_get_count_free_elements(vhd->ring);
+		if (!n) {
+			lwsl_user("dropping!\n");
+			break;
+		}
+
+		amsg.len = len;
+		/* notice we over-allocate by LWS_PRE */
+		amsg.payload = malloc(LWS_PRE + len);
+		if (!amsg.payload) {
+			lwsl_user("OOM: dropping\n");
+			break;
+		}
+
+		memcpy((char *)amsg.payload + LWS_PRE, in, len);
+		if (!lws_ring_insert(vhd->ring, &amsg, 1)) {
+			__minimal_destroy_message(&amsg);
+			lwsl_user("dropping!\n");
+			break;
+		}
+
+		/*
+		 * 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;
+
+	case LWS_CALLBACK_CLIENT_CLOSED:
+		vhd->client_wsi = NULL;
+		lws_timed_callback_vh_protocol(vhd->vhost, vhd->protocol,
+					       LWS_CALLBACK_USER, 1);
+		break;
+
+	/* rate-limited client connect retries */
+
+	case LWS_CALLBACK_USER:
+		lwsl_notice("%s: LWS_CALLBACK_USER\n", __func__);
+		if (connect_client(vhd))
+			lws_timed_callback_vh_protocol(vhd->vhost,
+						vhd->protocol,
+					        LWS_CALLBACK_USER, 1);
+		break;
+
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+#define LWS_PLUGIN_PROTOCOL_MINIMAL \
+	{  \
+		"lws-minimal-proxy", \
+		callback_minimal, \
+		sizeof(struct per_session_data__minimal), \
+		128, \
+		0, NULL, 0 \
+	}
+
+
+#if !defined (LWS_PLUGIN_STATIC)
+
+/* boilerplate needed if we are built as a dynamic plugin */
+
+static const struct lws_protocols protocols[] = {
+	LWS_PLUGIN_PROTOCOL_MINIMAL
+};
+
+LWS_EXTERN LWS_VISIBLE int
+init_protocol_minimal(struct lws_context *context,
+		      struct lws_plugin_capability *c)
+{
+	if (c->api_magic != LWS_PLUGIN_API_MAGIC) {
+		lwsl_err("Plugin API %d, library API %d", LWS_PLUGIN_API_MAGIC,
+			 c->api_magic);
+		return 1;
+	}
+
+	c->protocols = protocols;
+	c->count_protocols = ARRAY_SIZE(protocols);
+	c->extensions = NULL;
+	c->count_extensions = 0;
+
+	return 0;
+}
+
+LWS_EXTERN LWS_VISIBLE int
+destroy_protocol_minimal(struct lws_context *context)
+{
+	return 0;
+}
+#endif