/* 
================================================
	McastChat.c 
	Kristin Kaeding
	Multicast and Multithreaded Chat 
	
	LOGIN AS:
	McastChat <login_name>  <IP_addr>  <Port>

	IP must be multicast
	224.0.0.0 THRU 239.255.255.255
	Ctrl C to quit
	Enter BYE to logoff
=================================================
*/


#include <sys/types.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <sys/errno.h>
#include <netinet/in.h>

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <thread.h>
#include "multicast.h"

#define BUFSIZE         4096

                         
int		CreateMcastSocket();
void	sendMessage(int s);
void	getMessage(int inSock);
void	map_mcast_address(char * session_numb);

void    *Tthread(void* arg);
void    *Lthread(void* arg);

char	*GroupIPaddress ="224.4.4.4";			/* multicast group IP address */
char    *usrName = "kristin"; 
int		UDPport; 						/* port number */

u_char	LOOP=1, TimeToLive=3;					/* ttl value */
int CMcastSock = -1; 
int SMcastSock = -1;
thread_t thridT, thridL;                  
thread_t thrid_main;

struct sockaddr peer;
int len = sizeof(peer);

char *host;
int hostlen = sizeof(host);

 

int
main(int argc,char *argv[])
{
	
	/* parse the command line to get the multicast group address */
	switch (argc) {
        case    4:
			UDPport = atoi(argv[3]);
			GroupIPaddress= argv[2];
			usrName= argv[1];

                break;
        default:
                errexit("usage: McastChat <login_name>  <IP_addr>  <Port>\n");
    }

	/*string user name	default: kristin	*/
	/*must be multicast default: 224.4.4.4	*/
	/*udp port number	default: 3350		*/
  	
	/*  thr_setoncurrency(10);*/
	thrid_main = thr_self();
   
	printf("==================================\n");
	printf("Welcome to McastChat\n");
	printf("program by Kristin Kaeding\n");
	printf("==================================\n");
	printf("IP must be multicast\n");
	printf("224.0.0.0 THRU 239.255.255.255\n");
	printf("==================================\n");
	printf("Ctrl C to quit\n");
	printf("Enter BYE to logoff\n");
	printf("==================================\n");
	
	
	
    if ((CMcastSock = socket(PF_INET,SOCK_DGRAM, 0)) < 0)
    {
      printf("can't create socket: \n", sys_errlist[errno]);
		exit(-1);
    }
	printf("TALK socket created...\n");

    SMcastSock  = CreateMcastSocket(UDPport);
    /* OR SMcastSock  = passiveUDP(UDPport); */
	printf("LISTEN socket created...\n");
    
	
	/*
	LISTEN THREAD: creates socket and
	calls receivemessage which writes to stdout 
	and receives over mcast group
	*/
	thr_create(NULL, 0, &Lthread, (void*) SMcastSock,
		THR_DETACHED|THR_NEW_LWP, &thridL);
    thridL = thr_self();
	

	/*
	TALK THREAD: creates socket and 
	calls sendmessage which reads from stdin 
	and sends over mcast 
	*/
	thr_create(NULL, 0, &Tthread,(void*) CMcastSock, 
		THR_DETACHED|THR_NEW_LWP, &thridT);
    thridT = thr_self();
	
	
	/*waiting for both threads to terminate*/
	/*thr_join(thrid_main, (thread_t *)&thridL ,NULL);*/
	thr_join(thridT, NULL ,NULL);
	/*printf("Main Thread exiting...\n");*/
	thr_exit((void *)0);
	  
}





/*=================================== 
 *	Talk Thread using CMcastSock
 *====================================
 */
void*
Tthread(void* arg)
{
	
	int CMcastSock;

	CMcastSock = (int)arg;
    
    
    printf("IN TALK THREAD\n");
			
    setTTLvalue(CMcastSock,&TimeToLive);	/* setting theTTL value */
	setLoopback(CMcastSock,LOOP);			/*0=disable,1=enable loopback; default is enable*/
    sendMessage(CMcastSock);
    close(CMcastSock);
	
	thr_exit((void*)0);  
        
}
/*=================================== 
 *	Listen Thread, Lthread using SMcastSock
 *====================================
 */
void*
Lthread (void* arg)
{
	int SMcastSock;
	SMcastSock = (int)arg;

	printf("IN LISTEN THREAD\n");
	
	joinGroup(SMcastSock, GroupIPaddress);    
    getMessage(SMcastSock);
    leaveGroup(SMcastSock, GroupIPaddress);    
    close(SMcastSock);
        
	thr_exit((void*)0);
}


/*===================================================================
   This functions: allocates a socket for getting the group multicast messages
====================================================================*/
 
int CreateMcastSocket(int port)
{
  int s,length,err;
  struct sockaddr_in groupHost; /* multicast group host info structure */

  
  /* Get the multicast group host information */
  groupHost.sin_family=AF_INET;
  groupHost.sin_port=htons(port); 
  /* wildcard address: means it may receive any unicast 
     or multicast pkts destined to this port */
  groupHost.sin_addr.s_addr = htonl(INADDR_ANY); /*unicast ot mcast packets*/
  /* OR (this is the only part missing in passiveUDP())==>
       groupHost.sin_addr.s_addr = htonl(inet_addr(GroupIPaddress1)); 
     this way this server is restricted to listen for mcast packets ONLY*/
  
  /* Allocate a UDP socket and set the multicast options */

  if ((s = socket(PF_INET,SOCK_DGRAM, 0)) < 0)
  {
    printf("can't create socket: \n", sys_errlist[errno]);
    exit(-1);
  }

  /* allow multipule processes to bind to same multicast port */
  reusePort(s);
  
  /* bind the UDP socket to the mcast address to recv messages from the group */
  if((bind(s,(struct sockaddr *) &groupHost, sizeof(groupHost))== -1))
  {
    printf("error in bind\n");
    exit(2);
  }
  
  return s;  
}


/* ===================================================================
   This function reads the input from STDIN and sends it to the group 
=====================================================================*/
void 
sendMessage(int sockfd)
{
    
	int i, bytes=0;
	struct sockaddr_in dest;
	char sendBuf[BUFSIZE];
	char stdinBuf[BUFSIZE];
	char byeBuf[3] = "BYE";
	char atBuf[1] = "@";
	char format[2] = ": ";
	int n;
	/*char *lhost = "hawk";*/
	char *hst;

	/* send the message to the group */
	dest.sin_family = AF_INET;
	dest.sin_port =  UDPport;
	dest.sin_addr.s_addr = inet_addr(GroupIPaddress);

	/*
	if((gethostname(&host,hostlen))< 0){
		printf("error at gethostname\n");
		exit(-1);
	}

	memcpy(&host,&lhost,sizeof(host));
	*/
	hst = getenv("HOST");
	printf("host is %s \n", hst);
	while(fgets(stdinBuf, sizeof(stdinBuf), stdin) != NULL) {
				n = strlen(stdinBuf);
				stdinBuf[n] = '\0';
				
				if(strncmp("BYE",stdinBuf,3)==0){
					sprintf(sendBuf,"%s@%s: %s",usrName,hst,byeBuf);
					dest.sin_addr.s_addr = inet_addr(GroupIPaddress);
					if ( sendto(sockfd, sendBuf,strlen(sendBuf),0,(struct sockaddr *) &dest, sizeof(dest)) < 0 ){
						printf("error in sendto BYE \n");
						exit(-1);
					}
					/*exit will kill all threads*/
					exit(0);
				}
								
				sprintf(sendBuf,"%s@%s: %s",usrName,hst,stdinBuf);
				dest.sin_addr.s_addr = inet_addr(GroupIPaddress);
				if ( sendto(sockfd, sendBuf,strlen(sendBuf),0,(struct sockaddr *) &dest, sizeof(dest)) < 0 ){
					printf("error in sendto \n");
					exit(-1);
				}
	}
	   
  
}

/*=====================================================================
   Get the multicast message sent by the group and print out to STDOUT

	INFO ON GETTING PEER NAME:
	int getpeername(int s, struct sockaddr *name, int *namelen);
	note: this is unsafe in multithreaded applications. 
	Unsafe intefaces should be called only for the main thread
  
	STRUCTURE USED:
	struct sockaddr {
		u_char	sa_len;
		u_short sa_family;
		char	sa_data[14];
	};
	
====================================================================*/
void getMessage(int inSock)
{
  int i,bytes=0;
  char recvBuf[MAX_LEN];
  
  

  
	while(1){
	/*==============GET PEER================================
	if((getpeername(inSock, &peer, &len)) < 0)
	{
		printf("error in getpeername\n");
		exit(-1);
	}
	=======================================================*/	
	
		memset(recvBuf,'\0',MAX_LEN);
		/*bytes = recv(inSock,recvBuf,MAX_LEN,0);*/
		bytes = recvfrom( inSock, recvBuf,MAX_LEN,0, &peer, &len);
		if (bytes < 0){
			printf("error in reading from multicast socket\n");
			exit(-1);
		}
				
		else if(bytes == 0)
			printf("zero bytes read\n");
		else{ /* print the message to STDOUT */
			
			if (write(1,recvBuf,bytes) < 0){
				printf("error in write to STDOUT \n");
				exit(-1);
			}
			
		}
	}
}