/*----------------------------------------------------------------
 *    send-udp : send messages to a remote host, UDP-based
 *----------------------------------------------------------------
 */

#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.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 sockfd, ok, addr_in_size;
  u_short portnum;
  struct sockaddr_in *to;
  struct hostent *toinfo;
  char *msg, htoname[MAXHOSTNAMELEN];
  u_long toaddr;

  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];

  addr_in_size = sizeof(struct sockaddr_in);
  memset((char *)to,(char)0,addr_in_size);

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

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

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

    if(sendto(sockfd,msg,strlen(msg),0,(struct sockaddr *)to,
	      addr_in_size) == -1){
      fprintf(stderr,"Error %d in sendto: %s\n",errno,sys_errlist[errno]);
      exit(errno);
    }
  }
}




/*----------------------------------------------------------------
 *    rcv-udp : receive packets, UDP-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

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

  int sockfd, cc, addr_in_size;
  u_short portnum;
  struct sockaddr_in *my_addr, *from;
  char *msg;
  u_long fromaddr;

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

  case 2:
    portnum = (u_short)atoi(argv[1]);
    fprintf(stdout,"Receive UDP 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);
  };

  addr_in_size = sizeof(struct sockaddr_in);

  msg = (char *)malloc(MSGSIZE);
  from = (struct sockaddr_in *)malloc(addr_in_size);
  my_addr = (struct sockaddr_in *)malloc(addr_in_size);

  memset((char *)my_addr,(char)0,addr_in_size);
  my_addr->sin_family = AF_INET;
  my_addr->sin_addr.s_addr = htonl(INADDR_ANY);
  my_addr->sin_port = portnum;

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

  if(bind(sockfd, (struct sockaddr *)my_addr, addr_in_size) < 0){
    fprintf(stderr,"Error %d in bind: %s\n",errno,sys_errlist[errno]);
    if(errno != EADDRINUSE) exit(errno); 
  };

  fprintf(stdout,"Ready to receive\n");

  while(1){
    if((cc = recvfrom (sockfd,msg,MSGSIZE,0,(struct sockaddr *)from,
		       &addr_in_size)) == -1){
      fprintf(stderr,"Error %d in recvfrom: %s\n",
	      errno,sys_errlist[errno]);
      exit(errno);
    };
    fromaddr = from->sin_addr.s_addr;
    msg[cc] = '\0';
    fprintf(stdout,"From %s port %d: %s\n",
	    (gethostbyaddr((char *)&fromaddr,
			   sizeof(fromaddr),
			   AF_INET))->h_name,
	     from->sin_port,msg);

  }
}