/*
 * Copyright (c) 2002 - 2003
 * NetGroup, Politecnico di Torino (Italy)
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright 
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright 
 * notice, this list of conditions and the following disclaimer in the 
 * documentation and/or other materials provided with the distribution. 
 * 3. Neither the name of the Politecnico di Torino nor the names of its 
 * contributors may be used to endorse or promote products derived from 
 * this software without specific prior written permission. 
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 */





#include <errno.h>		// for the errno variable
#include <string.h>		// for strtok, etc
#include <stdlib.h>		// for malloc(), free(), ...
#include <pcap.h>		// for PCAP_ERRBUF_SIZE
#include <signal.h>		// for signal()
#include <pthread.h>
#include "rpcapd.h"
#include "fileconf.h"	// for the configuration file management
#include "pcap-remote.h"
#include "daemon.h"		// the true main() method of this daemon
#include "utils.h"		// Missing calls and such
#include "sockutils.h"	// for socket calls

#ifndef WIN32
#include <unistd.h>		// for exit()
#include <sys/wait.h>	// waitpid()
#else
#include "win32-svc.h"	// for Win32 service stuff
#endif


// Global variables
char hostlist[MAX_HOST_LIST + 1];		//!< Keeps the list of the hosts that are allowed to connect to this server
struct active_pars activelist[MAX_ACTIVE_LIST];		//!< Keeps the list of the hosts (host, port) on which I want to connect to (active mode)
int nullAuthAllowed;					//!< '1' if we permit NULL authentication, '0' otherwise
SOCKET sockmain;						//!< keeps the main socket identifier
char loadfile[MAX_LINE + 1];			//!< Name of the file from which we have to load the configuration
int passivemode= 1;						//!< '1' if we want to run in passive mode as well
struct addrinfo mainhints;				//!< temporary struct to keep settings needed to open the new socket
char address[MAX_LINE + 1];				//!< keeps the network address (either numeric or literal) to bind to
char port[MAX_LINE + 1];				//!< keeps the network port to bind to

extern char *optarg;	// for getopt()



// Function definition
void main_passive(void *ptr);
void main_active(void *ptr);


#ifndef WIN32
void main_cleanup_childs(int sign);
#endif


/*!
	\brief Prints the usage screen if it is launched in console mode.
*/
void printusage()
{
	char *usagetext =
	"USAGE:\n"
	" "  PROGRAM_NAME " [-b <address>] [-p <port>] [-6] [-l <host_list>] [-a <host,port>]\n"
	"        [-n] [-v] [-d] [-s <file>] [-f <file>]\n"
	"  -b <address>: the address to bind to (either numeric or literal).\n"
    "                Default: it binds to all local IPv4 addresses\n"
	"  -p <port>: the port to bind to. Default: it binds to port " RPCAP_DEFAULT_NETPORT "\n"
	"  -4: use only IPv4 (default both IPv4 and IPv6 waiting sockets are used)\n"
	"  -l <host_list>: a file that keeps the list of the hosts which\n"
	"                  are allowed to connect to this server (if more than one,\n"
	"                  list them one per line). We suggest to use \n"
	"                  literal names (instead of numeric ones) in order to avoid\n"
	"                  problems with different address families\n"
	"  -n: permit NULL authentication (usually used with '-l')\n"
	"  -a <host, port>: run in active mode when connecting to 'host' on port 'port'\n"
	"  -v: run in active mode only (default: if '-a' is specified, it accepts passive\n"
	"      connections as well\n"
	"  -d: run in daemon mode (UNIX only) or as a service (Win32 only)\n"
	"      Warning (Win32): this switch is provided automatically when the service\n"
	"      is started from the control panel\n"
	"  -s <file>: save the current configuration to file\n"
 	"  -f <file>: load the current configuration from file; all the switches\n"
  	"             specified from the command line are ignored\n"
   "  -h: print this help screen\n\n";

	printf(usagetext);
}



//! Program main
int main(int argc, char *argv[], char *envp[])
{
char savefile[MAX_LINE + 1];		// name of the file on which we have to save the configuration
int isdaemon= 0;					// Not null if the user wants to run this program as a daemon
int retval;							// keeps the returning value from several functions
char errbuf[PCAP_ERRBUF_SIZE + 1];	// keeps the error string, prior to be printed


	savefile[0]= 0;
	loadfile[0]= 0;
	hostlist[0]= 0;

	// Initialize errbuf
	memset(errbuf, 0, sizeof(errbuf) );

	if (sock_init(errbuf, PCAP_ERRBUF_SIZE) == -1)
	{
		SOCK_ASSERT(errbuf, 1);
		exit(-1);
	}

	strncpy(address, RPCAP_DEFAULT_NETADDR, MAX_LINE);
	strncpy(port, RPCAP_DEFAULT_NETPORT, MAX_LINE);

	// Prepare to open a new server socket
	memset(&mainhints, 0, sizeof(struct addrinfo));

	mainhints.ai_family = PF_UNSPEC;
	mainhints.ai_flags = AI_PASSIVE;	// Ready to a bind() socket
	mainhints.ai_socktype = SOCK_STREAM;

	// Getting the proper command line options
	while ((retval = getopt(argc, argv, "b:dhp:4l:na:s:f:v")) != -1)
	{
		switch (retval)
		{
			case 'b':
				strncpy(address, optarg, MAX_LINE);
				break;
			case 'p':
				strncpy(port, optarg, MAX_LINE);
				break;
			case '4':
				mainhints.ai_family = PF_INET;		// IPv4 server only
				break;
			case 'd':
				isdaemon= 1;
				break;
			case 'n':
				nullAuthAllowed= 1;
				break;
			case 'v':
				passivemode= 0;
				break;
			case 'l':
			{
				strncpy(hostlist, optarg, sizeof(hostlist) );
				break;
			}
			case 'a':
			{
			char *tmpaddress, *tmpport;
			int i= 0;

				tmpaddress= strtok(optarg, RPCAP_HOSTLIST_SEP);

				while ( (tmpaddress != NULL) && (i < MAX_ACTIVE_LIST) )
				{
					tmpport= strtok(NULL, RPCAP_HOSTLIST_SEP);

					snprintf(activelist[i].address, MAX_LINE, tmpaddress);
					
					if ( (tmpport == NULL) || (strcmp(tmpport, "DEFAULT") == 0) ) // the user choose a custom port
						snprintf(activelist[i].port, MAX_LINE, RPCAP_DEFAULT_NETPORT_ACTIVE);
					else
						snprintf(activelist[i].port, MAX_LINE, tmpport);

					tmpaddress = strtok(NULL, RPCAP_HOSTLIST_SEP);

					i++;
				}
				
				if (i > MAX_ACTIVE_LIST)
					SOCK_ASSERT("Only MAX_ACTIVE_LIST active connections are currently supported.", 1);

				// I don't initialize the remaining part of the structure, since
				// it is already zeroed (it is a global var)
				break;
			}
			case 'f':
				strncpy(loadfile, optarg, MAX_LINE);
				break;
			case 's':
				strncpy(savefile, optarg, MAX_LINE);
				break;
			case 'h':
				printusage();
				exit(0);
			default:
				break;
		}
	}

	if (savefile[0])
	{
		if (fileconf_save(savefile) )
			SOCK_ASSERT("Error when saving the configuration to file", 1);
	}

	// If the file does not exist, it keeps the settings provided by the command line
	if (loadfile[0])
		fileconf_read(0);

#ifdef linux
	// SIGTERM (i.e. kill -15) is not generated in WIN32, although it is included for ANSI compatibility
	signal(SIGTERM, main_cleanup);
	signal(SIGCHLD, main_cleanup_childs);
#endif

	// forking a daemon, if it is needed
	if (isdaemon)
	{
	#ifndef WIN32
	int pid;

		// Unix Network Programming, pg 336
		if ( (pid = fork() ) != 0)
			exit(0);		// Parent terminates

		// First child continues
		// Set daemon mode
		setsid();
		
		// generated under unix with 'kill -HUP', needed to reload the configuration
		signal(SIGHUP, fileconf_read);

		if ( (pid = fork() ) != 0)
			exit(0);		// First child terminates

		// LINUX WARNING: the current linux implementation of pthreads requires a management thread
		// to handle some hidden stuff. So, as soon as you create the first thread, two threads are
		// created. Fom this point on, the number of threads active are always one more compared
		// to the number you're expecting

		// Second child continues
//		umask(0);
//		chdir("/");
	#else
		// We use the SIGABRT signal to kill the Win32 service
		signal(SIGABRT, main_cleanup);

		// If this call succeeds, it is blocking on Win32
		if ( svc_start() != 1)
			SOCK_ASSERT(1, "Unable to start the service");

		// When the previous call returns, the entire application has to be stopped.
		exit(0);
	#endif
	}
	else	// Console mode
	{
		// Enable the catching of Ctrl+C
		signal(SIGINT, main_cleanup);

#ifndef WIN32
		// generated under unix with 'kill -HUP', needed to reload the configuration
		// We do not have this kind of signal in Win32
		signal(SIGHUP, fileconf_read);
#endif

		printf("Press CTRL + C to stop the server...\n");
	}

	// If we're a Win32 service, we have already called this function in the service_main
	main_startup();

	// The code should never arrive here (since the main_startup is blocking)
	//  however this avoids a compiler warning
	exit(0);
}



void main_startup(void)
{
char errbuf[PCAP_ERRBUF_SIZE + 1];	// keeps the error string, prior to be printed
struct addrinfo *addrinfo;				// keeps the addrinfo chain; required to open a new socket
int i;
#ifdef WIN32
	pthread_t threadId;					// Pthread variable that keeps the thread structures
#else
	pid_t pid;
#endif

	i= 0;
	addrinfo= NULL;
	memset(errbuf, 0, sizeof(errbuf) );

	// Starts all the active threads
	while ( (activelist[i].address[0] != 0) && (i < MAX_ACTIVE_LIST) )
	{
		activelist[i].ai_family= mainhints.ai_family;
		
#ifdef WIN32
		if ( pthread_create( &threadId, NULL, (void *) &main_active, (void *) &activelist[i]) )
		{
			SOCK_ASSERT("Error creating the active child thread", 1);
			continue;
		}
#else
		if ( (pid= fork() ) == 0)	// I am the child
		{
			main_active( (void *) &activelist[i]);
			exit(0);
		}
#endif
		i++;
	}

	/*
		The code that manages the active connections is not blocking; 
		vice versa, the code that manages the passive connection is blocking.
		So, if the user do not want to run in passive mode, we have to block
		the main thread here, otherwise the program ends and all threads
		are stopped.

		WARNING: this means that in case we have only active mode, the program does
		not terminate even if all the child thread terminates. The user has always to
		press Ctrl+C (or send a SIGTERM) to terminate the program.
	*/

	if (passivemode)
	{
	struct addrinfo *tempaddrinfo;

		// Do the work
		if (sock_initaddress((address[0]) ? address : NULL, port, &mainhints, &addrinfo, errbuf, PCAP_ERRBUF_SIZE) == -1)
		{
			SOCK_ASSERT(errbuf, 1);
			return;
		}

		tempaddrinfo= addrinfo;

		while (tempaddrinfo)
		{
			if ( (sockmain= sock_open(tempaddrinfo, SOCKOPEN_SERVER, SOCKET_MAXCONN, errbuf, PCAP_ERRBUF_SIZE)) == -1)
			{
				SOCK_ASSERT(errbuf, 1);
				tempaddrinfo= tempaddrinfo->ai_next;
				continue;
			}

#ifdef WIN32
			if ( pthread_create( &threadId, NULL, (void *) &main_passive, (void *) &sockmain ) )
			{
				SOCK_ASSERT("Error creating the passive child thread", 1);
				continue;
			}
#else
			if ( (pid= fork() ) == 0)	// I am the child
			{
				main_passive( (void *) &sockmain);
				return;
			}
#endif
			tempaddrinfo= tempaddrinfo->ai_next;
		}

		freeaddrinfo(addrinfo);
	}

	// All the previous calls are no blocking, so the main line of execution goes here
	// and I have to avoid that the program terminates
	while (1)
		pthread_suspend(10*60*1000); // it wakes up every 10 minutes; it seems to me reasonable
}


/*
	\brief Closes gracefully (more or less) the program.

	This function is called:
	- when we're running in console
	- when we're running as a Win32 service (in case we press STOP)

	It is not called when we are running as a daemon on UNIX, since
	we do not define a signal in order to terminate gracefully the daemon.

	This function makes a fast cleanup (it does not clean everything, as 
	you can see from the fact that it uses kill() on UNIX), closes
	the main socket, free winsock resources (on Win32) and exits the
	program.
*/
void main_cleanup(int sign)
{
#ifndef WIN32
	// Sends a KILL signal to all the processes
	// that share the same process group (i.e. kills all the childs)
	kill(0, SIGKILL);
#endif

	SOCK_ASSERT(PROGRAM_NAME " is closing.\n", 1);

	if (sockmain)
		closesocket(sockmain);
	sock_cleanup();

	/*
		This code is executed under the following conditions:
		- SIGTERM: we're under UNIX, and the user kills us with 'kill -15' 
		(no matter is we're a daemon or in a console mode)
		- SIGINT: we're in console mode and the user sends us a Ctrl+C 
		(SIGINT signal), no matter if we're UNIX or Win32

		In all these cases, we have to terminate the program.
		The case that still remains is if we're a Win32 service: in this case,
		we're a child thread, and we want just to terminate ourself. This is because
		the exit(0) will be invoked by the main thread, which is blocked waiting that
		all childs terminates. We are forced to call exit from the main thread otherwise
		the Win32 service control manager (SCM) does not work well.
	*/
	if ( (sign == SIGTERM) || (sign == SIGINT) )
		exit(0);
	else
		return;
}



#ifdef linux

void main_cleanup_childs(int sign)
{
pid_t pid;
int stat;

	// For reference, Stevens, pg 128

	while ( (pid= waitpid(-1, &stat, WNOHANG) ) > 0)
		SOCK_ASSERT("Child terminated", 1);

	return;
}

#endif





/*!
	\brief 'true' main of the program.

	It must be in a separate function because:
	- if we're in 'console' mode, we have to put the main thread waiting for a Ctrl+C
	(in order to be able to stop everything)
	- if we're in daemon mode, the main program must terminate and a new child must be 
	created in order to create the daemon

	\param ptr: it keeps the main socket handler (what's called 'sockmain' in the main() ), that
	represents the socket used in the main connection. It is a 'void *' just because pthreads
	want this format.
*/
void main_passive(void *ptr)
{
char errbuf[PCAP_ERRBUF_SIZE + 1];	// keeps the error string, prior to be printed
SOCKET sockctrl;				// keeps the socket ID for this control connection
struct sockaddr_storage from;	// generic sockaddr_storage variable
socklen_t fromlen;				// keeps the length of the sockaddr_storage variable
SOCKET sockmain;

#ifndef WIN32
	pid_t pid;
#endif

	sockmain= *((SOCKET *) ptr);
	// Initialize errbuf
	memset(errbuf, 0, sizeof(errbuf) );

	// main thread loop
	while (1)
	{
#ifdef WIN32
	pthread_t threadId;					// Pthread variable that keeps the thread structures
#endif
	struct daemon_slpars *pars;			// parameters needed by the daemon_serviceloop()

		// Connection creation
		fromlen = sizeof(struct sockaddr_storage);

		sockctrl= accept(sockmain, (struct sockaddr *) &from, &fromlen);
		
		if (sockctrl == -1)
		{
			// The accept() call can return this error when a signal is catched
			// In this case, we have simply to ignore this error code
			// Stevens, pg 124
#ifdef WIN32
			if (WSAGetLastError() == WSAEINTR)
#else
			if (errno == EINTR)
#endif
				continue;

			// Don't check for errors here, since the error can be due to the fact that the thread 
			// has been killed
			sock_geterror("accept(): ", errbuf, PCAP_ERRBUF_SIZE);
			SOCK_ASSERT(errbuf, 1);
			continue;
		}

		// checks if the connecting host is among the ones allowed
		if (sock_check_hostlist(hostlist, RPCAP_HOSTLIST_SEP, &from, errbuf, PCAP_ERRBUF_SIZE) < 0 )
		{
			rpcap_senderror(sockctrl, errbuf, PCAP_ERR_HOSTNOAUTH, NULL);
			sock_close(sockctrl, NULL, 0);
			continue;
		}


#ifdef WIN32
		// in case of passive mode, this variable is deallocated by the daemon_serviceloop()
		pars= (struct daemon_slpars *) malloc ( sizeof(struct daemon_slpars) );
		if (pars == NULL)
		{
			snprintf(errbuf, PCAP_ERRBUF_SIZE, "malloc() failed: %s", pcap_strerror(errno));
			continue;
		}

		pars->sockctrl= sockctrl;
		pars->activeclose= 0;		// useless in passive mode
		pars->isactive= 0;
		pars->nullAuthAllowed= nullAuthAllowed;

		if ( pthread_create( &threadId, NULL, (void *) &daemon_serviceloop, (void *) pars) )
		{
			SOCK_ASSERT("Error creating the child thread", 1);
			continue;
		}

#else
		if ( (pid= fork() ) == 0)	// I am the child
		{
			// in case of passive mode, this variable is deallocated by the daemon_serviceloop()
			pars= (struct daemon_slpars *) malloc ( sizeof(struct daemon_slpars) );
			if (pars == NULL)
			{
				snprintf(errbuf, PCAP_ERRBUF_SIZE, "malloc() failed: %s", pcap_strerror(errno));
				exit(0);
			}

			pars->sockctrl= sockctrl;
			pars->activeclose= 0;		// useless in passive mode
			pars->isactive= 0;
			pars->nullAuthAllowed= nullAuthAllowed;

			// Close the main socket (must be open only in the parent)
			closesocket(sockmain);

			daemon_serviceloop( (void *) pars);
			exit(0);
		}

		// I am the parent
		// Close the childsocket (must be open only in the child)
		closesocket(sockctrl);
#endif

		// loop forever, until interrupted
	}
}




/*!
	\brief 'true' main of the program in case the active mode is turned on.

	It does not have any return value nor parameters.
	This function loops forever trying to connect to the remote host, until the
	daemon is turned down.

	\param ptr: it keeps the 'activepars' parameters. It is a 'void *' just because pthreads
	want this format.
*/
void main_active(void *ptr)
{
char errbuf[PCAP_ERRBUF_SIZE + 1];	// keeps the error string, prior to be printed
SOCKET sockctrl;					// keeps the socket ID for this control connection
struct addrinfo hints;				// temporary struct to keep settings needed to open the new socket
struct addrinfo *addrinfo;			// keeps the addrinfo chain; required to open a new socket
struct active_pars *activepars;
struct daemon_slpars *pars;			// parameters needed by the daemon_serviceloop()


	activepars= (struct active_pars *) ptr;

	// Prepare to open a new server socket
	memset(&hints, 0, sizeof(struct addrinfo));
									// WARNING Currently it supports only ONE socket family among IPv4 and IPv6 
	hints.ai_family = AF_INET;		// PF_UNSPEC to have both IPv4 and IPv6 server
	hints.ai_socktype = SOCK_STREAM;
	hints.ai_family= activepars->ai_family;

	snprintf(errbuf, PCAP_ERRBUF_SIZE, "Connecting to host %s, port %s, using protocol %s",
			activepars->address, activepars->port, (hints.ai_family == AF_INET) ? "IPv4": 
			(hints.ai_family == AF_INET6) ? "IPv6" : "Unspecified");
	SOCK_ASSERT(errbuf, 1);

	// Initialize errbuf
	memset(errbuf, 0, sizeof(errbuf) );

	// Do the work
	if (sock_initaddress(activepars->address, activepars->port, &hints, &addrinfo, errbuf, PCAP_ERRBUF_SIZE) == -1)
	{
		SOCK_ASSERT(errbuf, 1);
		return;
	}

	while (1)
	{
	int activeclose;

		if ( (sockctrl= sock_open(addrinfo, SOCKOPEN_CLIENT, 0, errbuf, PCAP_ERRBUF_SIZE)) == -1)
		{
			SOCK_ASSERT(errbuf, 1);

			snprintf(errbuf, PCAP_ERRBUF_SIZE, "Error connecting to host %s, port %s, using protocol %s",
					activepars->address, activepars->port, (hints.ai_family == AF_INET) ? "IPv4": 
					(hints.ai_family == AF_INET6) ? "IPv6" : "Unspecified" );

			SOCK_ASSERT(errbuf, 1);

			pthread_suspend(RPCAP_ACTIVE_WAIT * 1000);

			continue;
		}

		pars= (struct daemon_slpars *) malloc ( sizeof(struct daemon_slpars) );
		if (pars == NULL)
		{
			snprintf(errbuf, PCAP_ERRBUF_SIZE, "malloc() failed: %s", pcap_strerror(errno));
			continue;
		}

		pars->sockctrl= sockctrl;
		pars->activeclose= 0;
		pars->isactive= 1;
		pars->nullAuthAllowed= nullAuthAllowed;

		daemon_serviceloop( (void *) pars);

		activeclose= pars->activeclose;

		free(pars);

		// If the connection is closed by the user explicitely, don't try to connect to it again
		// just exit the program
		if (activeclose == 1)
			break;
	}
}

