#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <stdarg.h>
#include <syslog.h>
#include <fcntl.h>
#include <semaphore.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <pthread.h>
#include <ctype.h>


// Buffer size, in bytes, used for copying in the Cat() function.
const size_t BUF_SIZE = 4096;

// Global variables
char g_program_name[100];	// Initialised from argv[0] in ParseArgs()

// Typedef for a signal handler function.
typedef void (* signal_handler_t) (int);

// Prototypes for functions in this file.
void ParseArgs (int, char **, struct in_addr *, struct in_addr *, struct in_addr *, struct in_addr *);
void Initialise (void);
void sig_child (int);
int CreateServerSocket (int);
void Daemonise (void);
void MainLoop (int);//, struct in_addr *, struct in_addr *, struct in_addr *, struct in_addr *);
void ClearList(void);
void Proxy (int, int);
struct accept * AcceptClientConnection (int);
void VerifyClient(void *);
struct client * Handshake(int);
int ConnectToServer (struct in_addr, unsigned short);
//void Cat (int, int);
void Cat (void *);
int NameToAddr (const char *, struct in_addr *);
int NameToPort (const char *, unsigned short *, const char *);
#ifdef __GNUC__
	void quit (const char *, ...) __attribute__ ((format (printf, 1, 2)));
	void pbomb (const char *, ...) __attribute__ ((format (printf, 1, 2)));
	void hbomb (const char *, ...) __attribute__ ((format (printf, 1, 2)));
#else
	void quit (const char *, ...);
	void pbomb (const char *, ...);
	void hbomb (const char *, ...);
#endif
void set_signal_handler (int, signal_handler_t);

#define __PORT__ 9000
#define __MOITA_FOI_SOLICITADA__ "moita"
#define __OK__ "ok"

struct accept
{
	int newfd;
	struct sockaddr_in sa;
};

struct main_loop
{
	int listen_fd,
		ra_1,
		ra_2,
		ra_3,
		ra_4;
};

struct client
{
	char * user;
	int client_fd;
	int jabber_fd;
	int keep_alive;
	time_t last_action;
	struct client * next;
	struct client * previous;
};

struct cat
{
	int in_fd,
		out_fd;
	int jabber,
		keep_alive;
	struct client * client;
};

struct client * clients = (struct client *)NULL;

pthread_mutex_t mutexsum;

int main (int argc, char ** argv)
{
	struct in_addr remote_addr_1,
				   remote_addr_2,
				   remote_addr_3,
				   remote_addr_4;
	int listen_fd_1,
		listen_fd_2,
		listen_fd_3,
		listen_fd_4,
		listen_fd_5;

	pthread_t port_9001,
			  port_9002,
			  port_9003,
			  port_9004,
			  port_9005;

	//ParseArgs (argc, argv, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4);

	// Create server socket before becoming a daemon so
	// there is still a chance to print an error message.
	listen_fd_1 = CreateServerSocket (9001);
	listen_fd_2 = CreateServerSocket (9002);
	listen_fd_3 = CreateServerSocket (9003);
	listen_fd_4 = CreateServerSocket (9004);
	listen_fd_5 = CreateServerSocket (9005);

	if ( listen_fd_1 < 0 )
		pbomb ("Unable to create server socket #1");

	if ( listen_fd_2 < 0 )
		pbomb ("Unable to create server socket #2");

	if ( listen_fd_3 < 0 )
		pbomb ("Unable to create server socket #3");

	if ( listen_fd_4 < 0 )
		pbomb ("Unable to create server socket #4");

	if ( listen_fd_5 < 0 )
		pbomb ("Unable to create server socket #5");

	//Daemonise ();

	//pthread_create(&port_900, NULL, (void *) &MainLoop, (void *) accept);
	MainLoop (listen_fd_1);//, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4); // never returns
	//MainLoop (listen_fd, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4); // never returns
	//MainLoop (listen_fd, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4); // never returns
	//MainLoop (listen_fd, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4); // never returns
	//MainLoop (listen_fd, &remote_addr_1, &remote_addr_2, &remote_addr_3, &remote_addr_4); // never returns

	syslog (LOG_ERR, "fim MainLoop(): %m");
	exit (EXIT_SUCCESS);
}

// ParseArgs()
// Parse the command line arguments to extract the remote
// and local adresses and port numbers, ra, rp, la & lp.
// Exit the program gracefully upon error.
void ParseArgs (int argc, char ** argv, struct in_addr * ra_1, struct in_addr * ra_2, struct in_addr * ra_3, struct in_addr * ra_4)
{
	// argv[0] = program name
	// argv[1] = remote_addr
	// argv[2] = remote_port
	// argv[3] = local_addr (optional)
	// argv[4] = local_port (optional)

	char * p = strrchr (argv[0], '/');

	strncpy (g_program_name, (p == NULL) ? argv[0] : p + 1, sizeof (g_program_name) - 1);

	if ( (argc < 5) || (argc > 5) )
	{
		fprintf (stderr, "usage: %s remote_addr_1 remote_addr_2 remote_addr_3 remote_addr_4\n", argv[0]);
		exit (EXIT_FAILURE);
	}

	if ( NameToAddr (argv[1], ra_1) )
		hbomb ("Unable to resolve \"%s\" to an ip address", argv[1]);

	if ( NameToAddr (argv[2], ra_2) )
		hbomb ("Unable to resolve \"%s\" to an ip address", argv[2]);

	if ( NameToAddr (argv[3], ra_3) )
		hbomb ("Unable to resolve \"%s\" to an ip address", argv[3]);

	if ( NameToAddr (argv[4], ra_4) )
		hbomb ("Unable to resolve \"%s\" to an ip address", argv[4]);
}

// Initialise()
// Setup syslog, signal handlers, and other intialisation.
void Initialise (void)
{
	openlog (g_program_name, LOG_PID, LOG_USER);
	syslog (LOG_INFO, "%s started", g_program_name);

	chdir ("/"); // Change working directory to the root.

	umask (0); // Clear our file mode creation mask

	//set_signal_handler (SIGCHLD, sig_child);

	//signal (SIGPIPE, SIG_IGN);
}

// CreateServerSocket()
// Create a socket, bind it to the specified address
// and port, and set it to listen for client connections.
// Returns < 0 on failure to bind, bombs on error otherwise,
// returns the fd of the new socket on success.
int CreateServerSocket (int port)
{
	int err,
		fd;
	const int on = 1;
	struct sockaddr_in sa;

	// Create a socket and get its descriptor.
	fd = socket (AF_INET, SOCK_STREAM, 0);
	if ( fd < 0 )
		syslog (LOG_ERR, "socket(): %m"), exit (EXIT_FAILURE);

	// Set SO_REUSEADDR socket option
	if ( setsockopt (fd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof (on)) < 0 )
		syslog (LOG_ERR, "setsockopt(fd%d, SO_REUSEADDR): %m", fd);

	// Load a sa structure with the specified address and port
	sa.sin_family = AF_INET;
	sa.sin_addr.s_addr = htonl(INADDR_ANY);
	sa.sin_port = htons (port);
	memset (sa.sin_zero, 0, sizeof (sa.sin_zero));

	// Bind our socket to the address and port specified
	err = bind (fd, (struct sockaddr *) &sa, sizeof (sa));
	if ( err < 0 )
	{
		syslog (LOG_ERR, "bind(): %m");
		return err;
	}

	// Tell socket to listen and queue up to 5 incoming connections.
	if ( listen (fd, 5) < 0 )
		syslog (LOG_ERR, "listen(): %m"), exit (EXIT_FAILURE);

	return fd;
}

// MainLoop()
// Classic concurrent server model.
// Wait for a client to connect, fork a child process
// to do the business with the client, parent process
// continues to wait for the next connection.
// This function does not return.
void MainLoop (int listen_fd)
{
	struct accept * client;
	unsigned int addr = 0;
	char buf[250];

	int bytes_rcvd,
		bytes_sent,
		usando_moita = 0,
		size_of_buffer,
		i;

	time_t inicio = time(NULL);

	for ( ; ; )
	{
		client = AcceptClientConnection (listen_fd);
		addr = ntohl(client->sa.sin_addr.s_addr);

		sprintf(buf,"%d.%d.%d.%d",
				(addr >> 24)  , (addr >> 16) & 0xFF ,
				(addr >> 8) & 0xFF ,  addr & 0xFF);

		printf("New connection: %s :: %d\n", buf, ntohs(client->sa.sin_port));

		bzero(buf, 250);

		if ( (bytes_rcvd = recv(client->newfd, buf, 128, 0)) < 1 )
			printf("error in recv #1\n");
		else
		{
			if ( strcmp(buf, __MOITA_FOI_SOLICITADA__) == 0 )
				if ( !usando_moita )
				{
					bzero(buf, 250);
					sprintf(buf, __OK__);
					size_of_buffer = sizeof(buf);
					for ( i = 0; i < size_of_buffer; i += bytes_sent )
					{
						bytes_sent = send (client->newfd, buf + i, sizeof(buf) - i, 0);

						if ( bytes_sent < 0 )
							break;
					}
				}
		}
	}
}

// AcceptClientConnection()
// waits for a tcp connect to the socket listen_fd, which
// must already be bound and set to listen on a local port.
// Bombs on error, returns the fd of the new socket on success.
struct accept * AcceptClientConnection (int listen_fd)
{
	int newfd;
	struct sockaddr_in sa;
	socklen_t socklen;

	syslog (LOG_INFO, "AcceptClientConnection(fd%d)", listen_fd);

	// Accept the connection and create a new socket for it.
	socklen = sizeof (sa);
	memset (&sa, 0, socklen);
	do
	{
		newfd = accept (listen_fd, (struct sockaddr *) &sa, &socklen);
	}
	while ( (newfd < 0) && (errno == EINTR) );

	syslog (LOG_INFO, "Accepted client connection on new socket fd%d", newfd);

	if ( newfd < 0 )
		syslog (LOG_ERR, "accept(): %m"), pthread_exit(0);

	if ( socklen != sizeof (sa) )
		syslog (LOG_ERR, "accept() screwed up!"), pthread_exit(0);

	struct accept * new_accept = (struct accept *) malloc(sizeof(struct accept));
	new_accept->newfd = newfd;
	new_accept->sa = sa;

	return (new_accept);
}

void VerifyClient(void * accept)
{
	int jabber_fd = (int)NULL;
	struct accept * client = (struct accept *) accept;
	struct client * user = (struct client *)NULL;
	struct cat * info;
	pthread_t cat_thread;

	unsigned int addr = 0;
	char buf[250];
	addr = ntohl(client->sa.sin_addr.s_addr);
	sprintf(buf,"%d.%d.%d.%d",
			(addr >> 24)  , (addr >> 16) & 0xFF ,
			(addr >> 8) & 0xFF ,  addr & 0xFF);
	//printf("New connection: %s\n", buf);

	//if ( strcmp(buf, "10.15.20.42") == 0 )//|| strcmp(buf, "10.15.20.202") == 0 )
	//{
	//	user = Handshake(client->newfd);
	//	jabber_fd = user->jabber_fd;
	//}

	if ( jabber_fd == (int)NULL )
	{
		//jabber_fd = ConnectToServer(client->jabber_addr, client->jabber_port);

		if ( user != (struct client *)NULL )
			user->jabber_fd = jabber_fd;
	}

	info = (struct cat *) malloc(sizeof(struct cat));

	info->out_fd = jabber_fd;
	info->in_fd = client->newfd;
	info->jabber = (int)NULL;
	info->keep_alive = (int)NULL;
	info->client = user;

	pthread_create(&cat_thread, NULL, (void *) &Cat, (void *)info );

	pthread_exit(0);
}

struct client * Handshake(int newfd)
{
	float is_new_client;// = (float) NULL;
	int bytes_rcvd,
		bytes_sent,
		i;

	unsigned char * const buf = (char *) malloc (sizeof(char) * 5);
	char * user = (char *) malloc(128 * sizeof(char)),
		 * pass = (char *) malloc(128 * sizeof(char));

	//struct client * clients = (struct client *)NULL;
	struct client * new_client = (struct client *)NULL;

	bzero(buf, 5);
	sprintf(buf, "user");
	for ( i = 0; i < sizeof(buf); i += bytes_sent )
	{
		bytes_sent = send (newfd, buf + i, sizeof(buf) - i, 0);

		if ( bytes_sent < 0 )
			break;
	}

	bzero(user, 128);
	if ( (bytes_rcvd = recv (newfd, user, 128, 0)) < 1 )
		pthread_exit(0);

	bzero(buf, 5);
	sprintf(buf, "pass");
	for ( i = 0; i < sizeof(buf); i += bytes_sent )
	{
		bytes_sent = send (newfd, buf + i, sizeof(buf) - i, 0);

		if ( bytes_sent < 0 )
			break;
	}

	bzero(pass, 128);
	if ( (bytes_rcvd = recv (newfd, pass, 128, 0)) < 1 )
		pthread_exit(0);

	pthread_mutex_lock (&mutexsum);
	if ( clients == (struct client *)NULL )
	{
		clients = (struct client *) malloc(sizeof(struct client));

		new_client = clients;
		new_client->previous = (struct client *)NULL;
		is_new_client = 1;
	}
	else
	{
		new_client = clients;
		while ( ((is_new_client = (float)strcmp(new_client->user, user)) != 0) && (new_client->next != (struct client *)NULL) )
			new_client = new_client->next;

		if ( is_new_client != 0 )
		{
			new_client->next = (struct client *) malloc(sizeof(struct client));
			new_client->next->previous = new_client;
			new_client = new_client->next;
		}
	}

	if ( is_new_client != 0 )
	{
		new_client->user = user;
		new_client->jabber_fd = (int)NULL;
		new_client->keep_alive = 1;
		new_client->next = (struct client *)NULL;
	}

	bzero(buf, 5);
	if ( is_new_client != 0 || new_client->jabber_fd == (int)NULL  )
		sprintf(buf, "new");
	else
		sprintf(buf, "rec");

	send (newfd, buf, 3, 0);

	new_client->client_fd = newfd;
	new_client->last_action = time(NULL);
	pthread_mutex_unlock(&mutexsum);

	return new_client;
}

// ConnectToServer()
// attempts a tcp connect to the server specified
// by addr and port.  Bombs on failure to connect,
// returns the fd of the new socket on success.
int ConnectToServer (struct in_addr addr, unsigned short port)
{
	// TODO: have a timeout for connect() - see Unix socket FAQ 6.2

	int fd, err;
	struct sockaddr_in sa;

	// Create a socket and get its descriptor.
	fd = socket (AF_INET, SOCK_STREAM, 0);

	if ( fd < 0 )
		syslog (LOG_ERR, "socket(): %m"), pthread_exit(0);//exit (EXIT_FAILURE);

	sa.sin_family = AF_INET;
	sa.sin_port = htons (port);
	sa.sin_addr = addr;
	memset (sa.sin_zero, 0, sizeof (sa.sin_zero));

	err = connect (fd, (struct sockaddr *) &sa, sizeof (sa));
	if (err < 0)
	{
		syslog (LOG_ERR, "Unable to connect socket fd%d to server: %m", fd);
		//exit (EXIT_FAILURE);
		pthread_exit(0);
	}

	syslog (LOG_INFO, "Connected socket fd%d to server", fd);

	return fd;
}

// Cat()
// read data from in_fd and write it to out_fd until
// the connection is closed by one of the peers.
// Data is copied using a dynamically allocated buffer.
//void Cat (int in_fd, int out_fd)
//void Cat (int in_fd, int out_fd)
void Cat (void * info)
{
	unsigned char * const buf_in = (char *) malloc (sizeof(char) * BUF_SIZE);
	unsigned char * const buf_out = (char *) malloc (sizeof(char) * BUF_SIZE);
	int bytes_rcvd_in = (int) NULL,
		bytes_sent_in = (int) NULL,
		bytes_rcvd_out = (int) NULL,
		bytes_sent_out = (int) NULL,
		i,
		in_fd,
		out_fd;
	struct cat * user = (struct cat *) info;
	in_fd = user->in_fd;
	out_fd = user->out_fd;

	syslog (LOG_INFO, "Cat(fd%d, fd%d)", in_fd, out_fd);

	if ( buf_in == NULL || buf_out == NULL )
		syslog (LOG_ERR, "malloc(): %m"), pthread_exit(0);

	fcntl(in_fd, F_SETFL, fcntl(in_fd, F_GETFL, 0) | O_NDELAY);
	fcntl(out_fd, F_SETFL, fcntl(out_fd, F_GETFL, 0) | O_NDELAY);

	bzero(buf_in, BUF_SIZE);
	bzero(buf_out, BUF_SIZE);
	do
	{
		bzero(buf_in, BUF_SIZE);
		if ( (bytes_rcvd_in = recv (in_fd, buf_in, BUF_SIZE, 0)) != 0 && strlen(buf_out) > 0 )
		{
			for ( i = 0; i < bytes_rcvd_out; i += bytes_sent_in )
			{
				bytes_sent_in = send (in_fd, buf_out + i, bytes_rcvd_out - i, 0);

				if ( bytes_sent_in < 0 )
					break;
			}
		}

		bzero(buf_out, BUF_SIZE);
		if ( (bytes_rcvd_out = recv (out_fd, buf_out, BUF_SIZE, 0)) != 0 && strlen(buf_in) > 0 )
		{
			//printf("\n%s\n", buf_in);
			for ( i = 0; i < bytes_rcvd_in; i += bytes_sent_out )
			{
				bytes_sent_out = send (out_fd, buf_in + i, bytes_rcvd_in - i, 0);

				if ( bytes_sent_out < 0 )
					break;
			}
		}
		usleep(500);
	}
	while ( (bytes_rcvd_in != 0) && (bytes_rcvd_out != 0) );

	if ( ((bytes_rcvd_in < 0) || (bytes_rcvd_out < 0)) && (errno != ECONNRESET) )
		syslog (LOG_ERR, "recv(): %m"), pthread_exit(0);

	if ( ((bytes_sent_in < 0) || (bytes_sent_out < 0)) && (errno != EPIPE) )
		syslog (LOG_ERR, "send(): %m"), pthread_exit(0);

	if ( user->jabber && !user->keep_alive )
	{
		shutdown(user->jabber, SHUT_RDWR);
		close(user->jabber);
	}
	pthread_exit(0);
	free (buf_in);
	free (buf_out);
}

// NameToAddress()
// Convert name to an ip address.
// Returns 0 on success, -1 on failure.
int NameToAddr (const char * name, struct in_addr * p_inaddr)
{
	struct hostent * he;

	// First, attempt to convert from string ip format
	// TODO: use inet_aton() instead
	p_inaddr->s_addr = inet_addr (name);
	if ( p_inaddr->s_addr != -1U ) // Success
		return 0;

	// Next, attempt to read from /etc/hosts or do a DNS lookup
	he = gethostbyname (name);
	if ( he != NULL ) // Success
	{
		memcpy (p_inaddr, he->h_addr, sizeof (struct in_addr));
		return 0;
	}

	return -1; // Failed to resolve name to an ip address
}

// NameToPort()
// Convert name to a port number. Name can either be a port name
// (in which case proto must also be set to either "tcp" or "udp")
// or name can be the ascii representation of the port number.
// Returns 0 on success, -1 on failure.
int NameToPort (const char * name, unsigned short * port, const char * proto)
{
	unsigned long lport;
	char * errpos;
	struct servent * se;

	// First, attempt to convert string to integer
	lport = strtoul (name, &errpos, 0);
	if ( (*errpos == 0) && (lport <= 65535) ) // Success
	{
		*port = lport;
		return 0;
	}

	// Next, attempt to read the string from /etc/services
	se = getservbyname (name, proto);
	if ( se != NULL) // Success
	{
		*port = ntohs (se->s_port);
		return 0;
	}

	return -1; // Failed to resolve port name to a number
}

// quit()
// Print an error message to stderr
// and syslog, then exit the program.
void quit (const char * fmt, ...) // quit with msg
{
	va_list ap;

	fflush (stdout);

	fprintf (stderr, "%s: ", g_program_name);

	va_start (ap, fmt);
	vfprintf (stderr, fmt, ap);
	va_end (ap);

	fputc ('\n', stderr);

	syslog (LOG_ERR, "I quit!");

	exit (EXIT_FAILURE);
}

// pbomb()
// Print an error message to stderr
// and syslog, then exit the program.
// pbomb() additionally include the
// string representation of errno.
void pbomb (const char * fmt, ...) // bomb with perror
{
	va_list ap;
	int errno_save = errno;
	char buf[100];

	fflush (stdout);

	fprintf (stderr, "%s: ", g_program_name);

	va_start (ap, fmt);
	vsnprintf (buf, sizeof (buf), fmt, ap);
	va_end (ap);

	errno = errno_save;
	perror (buf);

	syslog (LOG_ERR, "Bang!: %s: %m", buf);

	exit (EXIT_FAILURE);
}

// hbomb()
// Print an error message to stderr
// and syslog, then exit the program.
// hbomb() additionally include the
// string representation of h_errno.
void hbomb (const char * fmt, ...) // bomb with herror
{
	va_list ap;
	int h_errno_save = h_errno;
	char buf[100];

	fflush (stdout);

	fprintf (stderr, "%s: ", g_program_name);

	va_start (ap, fmt);
	vsnprintf (buf, sizeof (buf), fmt, ap);
	va_end (ap);

	h_errno = h_errno_save;
	herror (buf);

	syslog (LOG_ERR, "Bang!: %s: %s", buf, hstrerror (h_errno));

	exit (EXIT_FAILURE);
}

// set_signal_handler()
// Sets a signal handler function.
// Similar to signal() but this method
// is more portable between platforms.
void set_signal_handler (int signum, signal_handler_t sa_handler_func)
{
	struct sigaction act;

	act.sa_handler = sa_handler_func;
	sigemptyset (&(act.sa_mask));
	act.sa_flags = 0;

	if ( sigaction (signum, &act, NULL) < 0 )
	{
		syslog (LOG_ERR, "Error setting handler for signal %d: %m", signum);
		exit (EXIT_FAILURE);
	}
}