This is client code by using libwebsocket version 1.5
#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <string.h>
#include <assert.h>
#include <signal.h>
#include <syslog.h>
#include <sys/time.h>
#include <unistd.h>
#include <libwebsockets.h>
static volatile int force_exit = 0;
static int state, command_received = 0, forked = 0;
#define MAX_ECHO_PAYLOAD 1400
#define LOCAL_RESOURCE_PATH "./"
struct per_session_data {
unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + MAX_ECHO_PAYLOAD + LWS_SEND_BUFFER_POST_PADDING];
unsigned int len;
};
//for temporary storing data from tcpdump
struct per_session_data data1;
static int callback_echo(struct libwebsocket_context *context, struct libwebsocket *wsi, enum libwebsocket_callback_reasons reason, void *user, void *in, size_t len)
{
struct per_session_data *pss = (struct per_session_data *)user;
int n;
switch (reason) {
/* when the callback is used for client operations --> */
case LWS_CALLBACK_CLOSED:
case LWS_CALLBACK_CLIENT_CONNECTION_ERROR:
printf("Closed\n");
state = 0;
break;
case LWS_CALLBACK_ESTABLISHED:
case LWS_CALLBACK_CLIENT_ESTABLISHED:
printf("Client connected\n");
state = 2;
break;
/* we will receive our packet here*/
case LWS_CALLBACK_RECEIVE:
case LWS_CALLBACK_CLIENT_RECEIVE:
printf("Rx from server: %s\n", (char *)in);
if (!strcmp((char *)in, "tcpdump"))
{
command_received = 1;
}
break;
/* we will send our packet here */
case LWS_CALLBACK_CLIENT_WRITEABLE:
printf("client writing to server\n");
pss->len = sprintf((char *)&pss->buf[LWS_SEND_BUFFER_PRE_PADDING], "%s", data1.buf + LWS_SEND_BUFFER_PRE_PADDING);
n = libwebsocket_write(wsi, &pss->buf[LWS_SEND_BUFFER_PRE_PADDING], pss->len, LWS_WRITE_TEXT);
printf("Data: %s\n\n\n\n\n\n\n", &pss->buf[LWS_SEND_BUFFER_PRE_PADDING]);
//error handling for write fail and partial writes
if (n < 0) {
printf("ERROR %d writing to socket, hanging up\n", n);
return -1;
}
if (n < (int)pss->len) {
printf("Partial write\n");
return -1;
}
break;
default:
printf("default...\n");
break;
}
return 0;
}
/* List of available protocols */
static struct libwebsocket_protocols protocols[] = {
{
"default", /* name */
callback_echo, /* callback */
sizeof(struct per_session_data) /* per_session_data_size */
},
{
NULL, NULL, 0 /* End of list */
}
};
void sighandler(int sig)
{
force_exit = 1;
}
int main(int argc, char **argv)
{
//pipe stuff
int pipe_fd[2];
if (pipe(pipe_fd) < 0)
{
perror("PIPE:");
exit(-1);
}
//for libwebsocket_service
int n = 0;
//test port can be overidden
int port = 9000;
struct libwebsocket_context *context;
int opts = 0;
char interface_name[128] = "";
const char *interface = NULL;
int use_ssl = 0;
char ssl_cert[256] = LOCAL_RESOURCE_PATH"/libwebsockets-test-server.pem";
char ssl_key[256] = LOCAL_RESOURCE_PATH"/libwebsockets-test-server.key.pem";
int listen_port = 80;
struct lws_context_creation_info info;
char passphrase[256];
char uri[256] = "/";
char address[256], ads_port[256 + 30];
//lws servicing time intervals
int rate_us = 250000;
unsigned int oldus = 0;
struct libwebsocket *wsi;
//should check this
int debug_level = 2;
memset(&info, 0, sizeof info);
lwsl_notice("Built to support client operations\n");
//re-configuring server ip and port here
if (argc == 3)
{
strncpy(address, argv[1], sizeof(address) - 1);
address[sizeof(address) - 1] = '\0';
port = atoi(argv[2]);
}
else if (argc == 1)
{
strncpy(address, "localhost", sizeof(address) - 1);
address[sizeof(address) - 1] = '\0';
port = 9000;
}
else
{
printf("Try: ./client.exec <ip> <port>\n");
exit(-1);
}
/* we will only try to log things according to our debug_level */
setlogmask(LOG_UPTO (LOG_DEBUG));
openlog("lwsts", 0, LOG_DAEMON);
/* tell the library what debug level to emit and to send it to syslog */
lws_set_log_level(debug_level, lwsl_emit_syslog);
lwsl_notice("libwebsockets echo test - "
"(C) Copyright 2010-2015 Andy Green <andy@warmcat.com> - "
"licensed under LGPL2.1\n");
lwsl_notice("Running in client mode\n");
listen_port = CONTEXT_PORT_NO_LISTEN;
lwsl_info("requiring server cert validation againts %s\n", ssl_cert);
info.ssl_ca_filepath = ssl_cert;
info.port = listen_port;
info.iface = interface;
info.protocols = protocols;
#ifndef LWS_NO_EXTENSIONS
info.extensions = libwebsocket_get_internal_extensions();
#endif
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;
}
signal(SIGINT, sighandler);
n = 0;
while (n >= 0 && !force_exit)
{
//do connect only once
if (!state) {
state = 1;
printf("Client connecting to %s:%u....\n", address, port);
address[sizeof(address) - 1] = '\0';
sprintf(ads_port, "%s:%u", address, port & 65535);
wsi = libwebsocket_client_connect(context, address, port, use_ssl, uri, ads_port, ads_port, NULL, -1);
if (!wsi) {
printf("Client failed to connect to %s:%u\n", address, port);
goto bail;
}
}
if (command_received == 1 && !forked)
{
printf("Going to fork\n");
forked = 1;
pid_t child_pid = fork();
if (child_pid == -1)
{
perror("FORK:");
exit(-1);
}
else if (child_pid == 0)
{
close(pipe_fd[0]);
printf("Starting tcpdump\n");
if (dup2(pipe_fd[1], 1) < 0)
{
perror("DUP2:");
exit(-1);
}
//closing the connection to server for child
libwebsocket_context_destroy(context);
closelog();
char *cmd[] = {"tcpdump", "-i", "any", NULL};
if (execv("/usr/sbin/tcpdump", cmd) < 0)
{
perror("EXECV:");
exit(-1);
}
}
}
/* if (forked == 1)
{
close(pipe_fd[1]);
}
*/
if (command_received == 1)
{
//stay here if the pipe is empty else try to read max 1400 bytes of data
while ((data1.len = read(pipe_fd[0], data1.buf + LWS_SEND_BUFFER_PRE_PADDING, 1400)) <= 0);
//check if server wants any service
//printf("%s\n\n\n\n\n\n\n", data1.buf + LWS_SEND_BUFFER_PRE_PADDING);
libwebsocket_callback_on_writable(context, wsi);
}
//This fn times out every 10usec
n = libwebsocket_service(context, 10);
}
//bail: jump from while loop also if connect fails
bail:
libwebsocket_context_destroy(context);
printf("libwebsockets-test-echo exited cleanly\n");
closelog();
return 0;
}This is my server code by using socket.io
var io = require('socket.io')();
var middleware = require('socketio-wildcard')();
io.use(middleware);
io.on('connection', function(socket) {
console.log('On socket connection')
socket.on('*', function(event, data){
console.log("---- Event ----- : " + JSON.stringify(event));
console.log("---- Data ----- : " + JSON.stringify(data))
});
});
io.listen(9000, 'localhost');The client is unable to connect with server. when i tested client with strace it infinitely does receive as below
recv(8, "", 1, 0) = 0
recv(8, "", 1, 0) = 0
recv(8, "", 1, 0) = 0
.
.
.
.Please point out my mistake. Any help is appreciated.
Thanks
