/*----------------------------------------------------------------
 *    send-tcp : send messages to a remote host, TCP-based
 *----------------------------------------------------------------
 */


#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>

#define MSGSIZE 500

#ifndef IPPORT_MAX
#define IPPORT_MAX 65535  /* max port number */
#endif

#ifndef MAXHOSTNAMELEN
#define	MAXHOSTNAMELEN	256 
#endif

main(argc,argv)
  int argc;
  char *argv[];
{
  extern int errno;
  extern char *sys_errlist[];

  int s, ok, retry;
  struct sockaddr_in *to;
  struct hostent *toinfo;
  char *msg, htoname[MAXHOSTNAMELEN];
  u_long toaddr;
  u_short portnum;

  switch(argc) {
  case 1:
    fprintf(stdout,"Send messages to host: ");
    fscanf(stdin,"%s",htoname);
    fprintf(stdout,"on port number: ");
    fscanf(stdin,"%hu",&portnum);
    break;

  case 2:
    strcpy(htoname,argv[1]);
    fprintf(stdout,"Send messages to host %s on port number: ",argv[1]);
    fscanf(stdin,"%hu",&portnum);
    break;

  case 3:
    strcpy(htoname,argv[1]);
    portnum = (u_short)atoi(argv[2]);
    fprintf(stdout,"Send messages to host %s on port %d\n",
	    argv[1],portnum);
    break;

  default:
    fprintf(stderr,"%s: wrong number of arguments \n",argv[0]);
    fprintf(stderr,"Usage: %s [<hostname> [<portnumber>]]\n",argv[0]);
    exit(1);
  }

  if((portnum < IPPORT_RESERVED) || (portnum > IPPORT_MAX)){
    fprintf(stderr,"%s: bad port number\n",argv[0]);
    exit(1);
  };


  msg = (char *)malloc(MSGSIZE);
  to = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in));

  if((toinfo = gethostbyname(htoname)) == NULL) {
    fprintf(stderr,"Error %d in gethostbyname: %s\n",
	    errno,sys_errlist[errno]); 
    exit(errno);
  };
  toaddr = *(u_long *)toinfo->h_addr_list[0];

  to->sin_family = AF_INET;
  to->sin_addr.s_addr = toaddr;
  to->sin_port = htons(portnum);

  if((s = socket (PF_INET, SOCK_STREAM, 0)) == -1) {
    fprintf(stderr,"Error %d in socket: %s\n",errno,sys_errlist[errno]); 
    exit(errno);
  };

  retry = 1;
  while(retry) {
    if(connect(s,(struct sockaddr *)to,sizeof(struct sockaddr_in))== -1) {
      if(errno == ECONNREFUSED) {
	close(s);
	if((s = socket (PF_INET, SOCK_STREAM, 0)) == -1) {
	  fprintf(stderr,"Error %d in socket: %s\n",
		  errno,sys_errlist[errno]); 
	  exit(errno);
	};
	sleep(2);
	fprintf(stderr,"Retrying to connect\n");
      }
      else {
	fprintf(stderr,"Error %d in connect: %s\n",
		errno,sys_errlist[errno]); 
	exit(errno); 
      }
    }
    else retry = 0;
  };

  ok = 1;
  while(ok) {
    fprintf(stdout,"Message: ");
    scanf("%s",msg);
    fprintf(stdout,"\n");
    ok = (msg[0] != '0');

    if(send (s,msg,strlen(msg),0) == -1) {
      fprintf(stderr,"Error %d in send: %s\n",errno,sys_errlist[errno]);
      exit(errno);
    }
  }
  close(s);
}




/*----------------------------------------------------------------
 *    rcv-tcp : receive packets, TCP-based
 *----------------------------------------------------------------
 */


#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <netdb.h>
#include <errno.h>
#include <arpa/inet.h>

#define MSGSIZE 500

#ifndef IPPORT_MAX
#define IPPORT_MAX 65535  /* max port number */
#endif

#ifndef MAXHOSTNAMELEN
#define	MAXHOSTNAMELEN	256 
#endif


main(argc,argv)
     int argc;
     char *argv[];
{
  extern int errno;
  extern char *sys_errlist[];

  int s, s1, cc, ok, fromlen, pid;
  struct sockaddr_in *local_addr, *peer_addr;
  char *msg, *realmsg;
  u_long fromaddr;
  u_short portnum;

  switch(argc) {
  case 1:
    fprintf(stdout,"Receive TCP packets on port number: ");
    fscanf(stdin,"%hu",&portnum);
    break;

  case 2:
    portnum = (u_short)atoi(argv[1]);
    fprintf(stdout,"Receive TCP packets on port number: %d\n",portnum);
    break;

  default:
    fprintf(stderr,"%s: wrong number of arguments \n",argv[0]);
    fprintf(stderr,"Usage: %s [<portnumber>]\n",argv[0]);
    exit(1);
  }

  if((portnum < IPPORT_RESERVED)|| (portnum > IPPORT_MAX)) {
    fprintf(stderr,"%s: bad port number\n",argv[0]);
    exit(1);
  };


  msg = (char *)malloc(MSGSIZE);
  realmsg = (char *)malloc(MSGSIZE);
  peer_addr = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in));
  local_addr = (struct sockaddr_in *)malloc(sizeof(struct sockaddr_in));

  local_addr->sin_family = AF_INET;
  local_addr->sin_addr.s_addr = htonl(INADDR_ANY);
  local_addr->sin_port = htons(portnum);

  if((s = socket (PF_INET, SOCK_STREAM, 0)) == -1){
    fprintf(stderr,"Error %d in socket: %s\n",errno,sys_errlist[errno]); 
    exit(errno);
  };

  if(bind(s, (struct sockaddr *)local_addr,
	  sizeof(struct sockaddr_in)) == -1){
    fprintf(stderr,"Error %d in bind: %s\n",errno,sys_errlist[errno]);
    exit(errno); 
  };

  if(listen(s,5) == -1){
      fprintf(stderr,"Error %d in listen: %s\n",errno,sys_errlist[errno]); 
      exit(errno);
    };

  fprintf(stdout,"Ready to accept connections\n");

  while(1){
    fromlen = sizeof(struct sockaddr_in);
    if((s1 = accept(s,(struct sockaddr *)peer_addr,&fromlen)) == -1){
      fprintf(stderr,"Error %d in accept: %s\n",errno,sys_errlist[errno]); 
      exit(errno);
    };
    pid = fork(); /* create a son to handle the connection */
    switch(pid){
    case -1:
      fprintf(stderr,"Error %d in fork: %s\n",errno,sys_errlist[errno]); 
      exit(errno);

    case 0:
      ok = 1;
      while(ok){
	if((cc = recv (s1,msg,MSGSIZE,0)) == -1){
	  fprintf(stderr,"Error %d in recv: %s\n",
		  errno,sys_errlist[errno]);
	  exit(errno);
	};
	fromaddr = peer_addr->sin_addr.s_addr;
	strncpy(realmsg,msg,cc);
	realmsg[cc] = '\0';
	fprintf(stdout,"From %s : %s\n",
		(gethostbyaddr((char *)&fromaddr,
			       sizeof(fromaddr),AF_INET))->h_name,realmsg);
	ok = (realmsg[0] != '0');
      }
      shutdown(s1,2);
      exit(0);
    
    default:
      close(s1);
    }
  }
}