add very small websocket example

simple_websockets/main.c

@@ -0,0 +1,224 @@
+/*
+ * main.c
+ *
+ * Copyright 2016 Edward V. Emelianov <eddy@sao.ru, edward.emelianoff@gmail.com>
+ *
+ * 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 2 of the License, or
+ * (at your option) 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <signal.h>
+#include <libwebsockets.h>
+#include <pthread.h>
+#include <sys/prctl.h>
+#include <time.h>
+
+#include "dbg.h"
+#include "que.h"
+
+#define MESSAGE_LEN        (512)
+#define FRAME_SIZE         (LWS_SEND_BUFFER_PRE_PADDING + MESSAGE_LEN + LWS_SEND_BUFFER_POST_PADDING)
+
+
+char *client_IP = NULL; // IP of first connected client
+volatile int stop = 0;
+pthread_mutex_t command_mutex, ip_mutex;
+
+static void interrupt(_U_ int signo) {
+	stop = 1;
+}
+
+
+int ws_write(struct lws *wsi_in, char *str){
+	if (!str || !wsi_in)
+		return -1;
+	unsigned char buf[FRAME_SIZE];
+	int n;
+	size_t len = strlen(str);
+	if(len > MESSAGE_LEN) len = MESSAGE_LEN;
+	memcpy(buf + LWS_SEND_BUFFER_PRE_PADDING, str, len);
+	n = lws_write(wsi_in, buf + LWS_SEND_BUFFER_PRE_PADDING, len, LWS_WRITE_TEXT);
+	DBG("write %s\n", str);
+	return n;
+}
+
+void websig(char *command){
+	/*while(data_in_buf);
+	pthread_mutex_lock(&command_mutex);
+	strncpy(cmd_buf, command, CMDBUFLEN);
+	data_in_buf = 1;
+	pthread_mutex_unlock(&command_mutex);*/
+	DBG("get message: %s\n", command);
+}
+
+static int control_callback(struct lws *wsi,
+							enum lws_callback_reasons reason, void *user,
+							void *in, size_t len){
+	char client_name[128];
+	char client_ip[128];
+	control_data *dat = (control_data *) user;
+	char *msg = (char*) in;
+	void parse_que_msg(control_data *d){
+		char *M;
+		if((M = get_message_from_que(d))){
+			ws_write(wsi, M);
+		}
+	}
+    switch (reason) {
+		case LWS_CALLBACK_ESTABLISHED:
+			memset(dat, 0, sizeof(control_data));
+			pthread_mutex_lock(&ip_mutex);
+			lws_get_peer_addresses(wsi, lws_get_socket_fd(wsi),
+						client_name, 128, client_ip, 128);
+			if(!client_IP)
+				client_IP = strdup(client_ip);
+			else if(strcmp(client_IP, client_ip)){
+				char buf[256];
+				snprintf(buf, 255, "Already connected from %s.<br>Please, disconnect.", client_IP);
+				DBG("Already connected\n");
+				put_message_to_que(buf, dat);
+				snprintf(buf, 255, "Try of connection from %s", client_ip);
+				glob_que(buf);
+				dat->already_connected = 1;
+			}
+			pthread_mutex_unlock(&ip_mutex);
+			lws_callback_on_writable(wsi);
+		break;
+		case LWS_CALLBACK_SERVER_WRITEABLE:
+			if(dat->num)
+				parse_que_msg(dat);
+			if(!dat->already_connected && global_que.num)
+				parse_que_msg(&global_que);
+			usleep(500);
+			lws_callback_on_writable(wsi);
+			return 0;
+		break;
+		case LWS_CALLBACK_RECEIVE:
+			if(!dat->already_connected)
+				websig(msg);
+		break;
+		case LWS_CALLBACK_CLOSED:
+			DBG("closed\n");
+			if(!dat->already_connected){
+				pthread_mutex_lock(&ip_mutex);
+				free(client_IP);
+				client_IP = NULL;
+				pthread_mutex_unlock(&ip_mutex);
+			}
+		break;
+	}
+	return 0;
+}
+
+struct lws_protocols protocols[] = {
+	{
+		"IRBIS_control",			// name
+		control_callback,			// callback
+		sizeof(control_data),		// control_data_size
+		FRAME_SIZE,					// max frame size / rx buffer
+		0, NULL						// id, user
+	},
+	{ NULL, NULL, 0, 0, 0, NULL} /* terminator */
+};
+
+void *websock_thread(_U_ void *buf){
+	struct lws_context_creation_info info;
+	struct lws_context *context;
+
+	memset(&info, 0, sizeof info);
+	info.port = 9999;
+	info.iface = NULL;
+	info.protocols = protocols;
+	info.extensions = lws_get_internal_extensions();
+	info.ssl_cert_filepath = NULL;
+	info.ssl_private_key_filepath = NULL;
+	info.gid = -1;
+	info.uid = -1;
+	info.options = 0;
+
+	context = lws_create_context(&info);
+	if (context == NULL) {
+		lwsl_err("libwebsocket init failed\n");
+		stop = 1;
+	}
+	while (!stop) {
+		lws_service(context, 50);
+	}
+	usleep(10);
+	lws_context_destroy(context);
+	return NULL;
+}
+
+void *worker_thread(_U_ void* buf){
+	time_t t = time(NULL), oldt;
+	while(!stop){
+		oldt = t;
+		if(client_IP){
+			glob_que(ctime(&t));
+		}
+		while((t = time(NULL)) == oldt) usleep(1000);
+	}
+}
+
+static void main_proc(){
+	pthread_t ws_thread, wr_thread;
+	if(pthread_create(&ws_thread, NULL, websock_thread, NULL)){
+		fprintf(stderr, "Can't create websocket thread!\n");
+		stop = 1;
+		return;
+	}
+	if(pthread_create(&wr_thread, NULL, worker_thread, NULL)){
+		fprintf(stderr, "Can't create worker thread!\n");
+		stop = 1;
+		return;
+	}
+	while(!stop){
+	/*	pthread_mutex_lock(&command_mutex);
+		if(data_in_buf) process_buf(cmd_buf);
+		data_in_buf = 0;
+		pthread_mutex_unlock(&command_mutex);*/
+		usleep(1000); // give another treads some time to fill buffer
+	}
+	DBG("stop threads");
+	pthread_cancel(ws_thread);
+	pthread_cancel(wr_thread);
+	pthread_join(ws_thread, NULL);
+	pthread_join(wr_thread, NULL);
+	DBG("return main_proc");
+}
+
+int main(void) {
+	signal(SIGINT, interrupt);
+	signal(SIGTERM, interrupt);
+	signal(SIGQUIT, SIG_IGN);
+	signal(SIGTSTP, SIG_IGN);
+	while(1){
+		if(stop) return 0;
+		pid_t childpid = fork();
+		if(childpid){
+			DBG("Created child with PID %d\n", childpid);
+			wait(NULL);
+			DBG("Child %d died\n", childpid);
+		}else{
+			prctl(PR_SET_PDEATHSIG, SIGTERM); // send SIGTERM to child when parent dies
+			main_proc();
+			return 0;
+		}
+	}
+	return 0;
+}