/** Simple WebSocket relay facilitating client-to-client connections.
*
* @author Steffen Vogel <stvogel@eonerc.rwth-aachen.de>
* @copyright 2018, Institute for Automation of Complex Power Systems, EONERC
* @license GNU General Public License (version 3)
*
* VILLASnode
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*********************************************************************************/
#include <iostream>
#include <vector>
#include <map>
#include <queue>
#include <string>
#include <utility>
#include <memory>
#include <string.h>
#include <spdlog/spdlog.h>
#include <spdlog/sinks/stdout_color_sinks.h>
#include <villas/copyright.hpp>
#include <libwebsockets.h>
auto console = spdlog::stdout_color_mt("console");
/** The libwebsockets server context. */
static lws_context *context;
/** The libwebsockets vhost. */
static lws_vhost *vhost;
/* Forward declarations */
lws_callback_function protocol_cb;
class Session;
class Connection;
static std::map<std::string, Session *> sessions;
class InvalidUrlException { };
struct Options {
bool loopback;
} opts;
class Frame : public std::vector<uint8_t> {
public:
Frame() {
// lws_write() requires LWS_PRE bytes in front of the payload
insert(end(), LWS_PRE, 0);
}
uint8_t * data() {
return std::vector<uint8_t>::data() + LWS_PRE;
}
size_type size() {
return std::vector<uint8_t>::size() - LWS_PRE;
}
};
class Session {
public:
typedef std::string Identifier;
static Session * get(lws *wsi)
{
char uri[64];
/* We use the URI to associate this connection to a session
* Example: ws://example.com/node_1
* Will select the session with the name 'node_1'
*/
/* Get path of incoming request */
lws_hdr_copy(wsi, uri, sizeof(uri), WSI_TOKEN_GET_URI);
if (strlen(uri) <= 0)
throw InvalidUrlException();
Identifier sid = uri;
auto it = sessions.find(sid);
if (it == sessions.end()) {
return new Session(sid);
}
else {
console->info("Found existing session: {}", sid);
return it->second;
}
}
Session(Identifier sid) :
identifier(sid)
{
console->info("Session created: {}", identifier);
sessions[sid] = this;
}
~Session()
{
console->info("Session destroyed: {}", identifier);
sessions.erase(identifier);
}
Identifier identifier;
std::map<lws *, Connection *> connections;
};
class Connection {
protected:
lws *wsi;
std::shared_ptr<Frame> currentFrame;
std::queue<std::shared_ptr<Frame>> outgoingFrames;
Session *session;
char name[128];
char ip[128];
public:
Connection(lws *w) :
wsi(w),
currentFrame(std::make_shared<Frame>()),
outgoingFrames()
{
session = Session::get(wsi);
session->connections[wsi] = this;
lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi), name, sizeof(name), ip, sizeof(ip));
console->info("New connection established: session={}, remote={} ({})", session->identifier, name, ip);
}
~Connection() {
console->info("Connection closed: session={}, remote={} ({})", session->identifier, name, ip);
session->connections.erase(wsi);
if (session->connections.empty())
delete session;
}
void write() {
while (!outgoingFrames.empty()) {
std::shared_ptr<Frame> fr = outgoingFrames.front();
lws_write(wsi, fr->data(), fr->size(), LWS_WRITE_BINARY);
outgoingFrames.pop();
}
}
void read(void *in, size_t len) {
currentFrame->insert(currentFrame->end(), (uint8_t *) in, (uint8_t *) in + len);
if (lws_is_final_fragment(wsi)) {
console->debug("Received frame, relaying to {} connections", session->connections.size() - (opts.loopback ? 0 : 1));
for (auto p : session->connections) {
auto c = p.second;
/* We skip the current connection in order
* to avoid receiving our own data */
if (opts.loopback == false && c == this)
continue;
c->outgoingFrames.push(currentFrame);
lws_callback_on_writable(c->wsi);
}
currentFrame = std::make_shared<Frame>();
}
}
};
/** List of libwebsockets protocols. */
lws_protocols protocols[] = {
{
.name = "live",
.callback = protocol_cb,
.per_session_data_size = sizeof(Connection),
.rx_buffer_size = 0
},
{ NULL /* terminator */ }
};
/** List of libwebsockets extensions. */
static const lws_extension extensions[] = {
{
"permessage-deflate",
lws_extension_callback_pm_deflate,
"permessage-deflate"
},
{
"deflate-frame",
lws_extension_callback_pm_deflate,
"deflate_frame"
},
{ NULL /* terminator */ }
};
static void logger(int level, const char *msg) {
auto log = spdlog::get("lws");
char *nl = (char *) strchr(msg, '\n');
if (nl)
*nl = 0;
/* Decrease severity for some errors. */
if (strstr(msg, "Unable to open") == msg)
level = LLL_WARN;
switch (level) {
case LLL_ERR: log->error("{}", msg); break;
case LLL_WARN: log->warn( "{}", msg); break;
case LLL_INFO: log->info( "{}", msg); break;
default: log->debug("{}", msg); break;
}
}
int protocol_cb(lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len)
{
Connection *c = reinterpret_cast<Connection *>(user);
switch (reason) {
case LWS_CALLBACK_ESTABLISHED: {
try {
new (c) Connection(wsi);
}
catch (InvalidUrlException e) {
lws_close_reason(wsi, LWS_CLOSE_STATUS_PROTOCOL_ERR, (unsigned char *) "Invalid URL", strlen("Invalid URL"));
return -1;
}
break;
}
case LWS_CALLBACK_CLOSED:
c->~Connection();
break;
case LWS_CALLBACK_SERVER_WRITEABLE:
c->write();
break;
case LWS_CALLBACK_RECEIVE:
c->read(in, len);
break;
default:
break;
}
return 0;
}
void usage()
{
std::cout << "Usage: villas-relay [OPTIONS]" << std::endl;
std::cout << " OPTIONS is one or more of the following options:" << std::endl;
std::cout << " -d LVL set debug level" << std::endl;
std::cout << " -p PORT the port number to listen on" << std::endl;
std::cout << " -P PROT the websocket protocol" << std::endl;
std::cout << " -V show version and exit" << std::endl;
std::cout << " -h show usage and exit" << std::endl;
std::cout << std::endl;
villas::print_copyright();
}
int main(int argc, char *argv[])
{
/* Initialize logging */
spdlog::stdout_color_mt("lws");
lws_set_log_level((1 << LLL_COUNT) - 1, logger);
/* Start server */
lws_context_creation_info ctx_info = { 0 };
ctx_info.options = LWS_SERVER_OPTION_EXPLICIT_VHOSTS | LWS_SERVER_OPTION_DO_SSL_GLOBAL_INIT;
ctx_info.gid = -1;
ctx_info.uid = -1;
ctx_info.protocols = protocols;
ctx_info.extensions = extensions;
ctx_info.port = 8088;
char c, *endptr;
while ((c = getopt (argc, argv, "hVp:P:ld:")) != -1) {
switch (c) {
case 'd':
spdlog::set_level(spdlog::level::from_str(optarg));
break;
case 'p':
ctx_info.port = strtoul(optarg, &endptr, 10);
goto check;
case 'P':
protocols[0].name = optarg;
break;
case 'l':
opts.loopback = true;
break;
case 'V':
villas::print_version();
exit(EXIT_SUCCESS);
case 'h':
case '?':
usage();
exit(c == '?' ? EXIT_FAILURE : EXIT_SUCCESS);
}
continue;
check: if (optarg == endptr) {
console->error("Failed to parse parse option argument '-{} {}'", c, optarg);
exit(EXIT_FAILURE);
}
}
if (argc - optind < 0) {
usage();
exit(EXIT_FAILURE);
}
context = lws_create_context(&ctx_info);
if (context == NULL) {
console->error("WebSocket: failed to initialize server context");
exit(EXIT_FAILURE);
}
vhost = lws_create_vhost(context, &ctx_info);
if (vhost == NULL) {
console->error("WebSocket: failed to initialize virtual host");
exit(EXIT_FAILURE);
}
for (;;)
lws_service(context, 100);
return 0;
}