/* client1udp.c - a client program that uses the socket interface to udp */
/* THIS PROGRAM IS ADAPTED FROM HANDOUT OF CS820 OS PROGRAMMING
 * THE ORIGINAL AUTHOR SHOULD BE PROF. BOB RUSSELL
 * MODIFIED BY LIN @OCT,2001 
 */

#include <stdio.h>
#include <stdlib.h>
#ifdef __linux__
#ifndef __USE_BSD
#define __USE_BSD
#endif
#endif
#include <unistd.h>
#include <string.h>
#include <sys/times.h>   
#include <sys/param.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#ifdef __osf__
/* on DECUNIX no standard header file containns a prototype for this function
 * however, the function is in the standard c library (libc.a )
 */

extern void herror( char * name );
#endif

/* on solaris this program must be linked with -lnsl and -lsocket to load the
 * routines defined in the socket library.
 * also on Solaris <netdb.h> contains a prototype for herror(),  but it is 
 * NOT defined in the standard c library. therefore, the separate file herror. 
 * c must  be compiled and linked too
 */

#include "client.h"
#include "timer.h"

#define ITERATIONS  100
#define AMOUNT      1
#define MAXAMOUNT   10000000
 
char    data[MAXAMOUNT];


void client( int server_port, char * server_name, int argc, char * argv[] )
{
	int n, fd;
	int count, iterations=0, amount=0;
	struct 	sockaddr_in	address;
	struct	hostent		*node_ptr;
	char 			local_node[ MAXHOSTNAMELEN ] ;
    struct tms              tmsstart, tmsstop;
    clock_t                 start, stop;

    if( argc > 0 )
        iterations = atoi(argv[0]);
    if( iterations <= 0 )
        iterations = ITERATIONS;
    if( argc > 1 )
        amount = atoi(argv[1]);
    if( amount <= 0 )
        amount = AMOUNT;
    if( amount > MAXAMOUNT )
        amount = MAXAMOUNT;

	data[ MAXAMOUNT - 1 ] = '\0';

    fprintf(stderr, "udpclient: %d iterations, %d bytes each\n",
                                                        iterations, amount);

	/* set up the name of the remote host interface for the server */
	if ( server_name == NULL )
	{
		/* default to name of local_node */
		if ( gethostname( local_node, MAXHOSTNAMELEN ) < 0 )
		{
			perror( "client1udp gethostname" );
			exit( EXIT_FAILURE );
		}
		server_name = local_node;
	}/* end of if */

	/* get structure for remote host interface on which server is listening */
	if ( ( node_ptr = gethostbyname( server_name ) ) == NULL )
	{
		herror( server_name );
		exit( EXIT_FAILURE );
	}

	/* set up Internet address structure for the server */
	memset( &address, 0, sizeof( struct sockaddr_in ) ) ;
	address.sin_family = node_ptr->h_addrtype; 	/* should be AF_INET */
 	address.sin_port = htons( server_port );

	memcpy( &address.sin_addr, node_ptr->h_addr, node_ptr->h_length );

	fprintf(stderr, "udpclient:will send to server at port %d on node %s, \n", 
					 server_port, node_ptr->h_name );

	fprintf(stderr, "	internet address %s\n", inet_ntoa( address.sin_addr) );

	/* open an internet udp socket */
	if ( ( fd = socket( PF_INET,  SOCK_DGRAM, 0 ) ) < 0 )
	{
		perror( "client1udp socket" );
		exit( EXIT_FAILURE );
	}

	/* send special packet to anounce begin of this transmission */
	sprintf( data, "-2 %d ",iterations ); 
	data[ 20 ] = '\0';
    sendto(fd, data, 21, 0,
				  (struct sockaddr* )&address, sizeof( address ) ); 

    if( (start = times(&tmsstart)) < 0 )
        exit(EXIT_FAILURE);

    /*  now transmit data messages to server */
	/* a UDP sequence number is added on the beginning of each packet */
	/* this sequence will be used by server to count the packet loss*/
    for( count = 0;  count < iterations;  count++ )
    {
		sprintf( data, "%d ", count );

        if( ( n = sendto(fd, data, amount, 0,
				  (struct sockaddr* )&address, sizeof( address ) ) )!=amount ) 
		{
			if ( n < 0 )
			{
				perror( "udpclient sendto");
				break;
			}
			else
			{
			fprintf( stderr, "udpclient: really sent %d bytes, attempted %d\n",
						n, amount );
			break;
			}
		}
    }/* end of for */

    if( (stop = times(&tmsstop)) < 0 )
        exit(EXIT_FAILURE);
 
	/* send special packet to anounce end of this transmission */
	sprintf( data, "-1 %d ",iterations ); 
	data[ 20 ] = '\0';
    sendto(fd, data, 21, 0,
				  (struct sockaddr* )&address, sizeof( address ) ); 
    fprintf(stderr, "udpclient: finished %d iterations of %d bytes each\n",
                                                            count, amount);
 
    pr_times(stderr, stop-start, &tmsstart, &tmsstop);

	/* close the udp socket */
	if ( close( fd ) < 0 )
	{
		perror( "client1udp close " );
		exit( EXIT_FAILURE );
	}

	fprintf(stderr, "\n" );

}/* end of client */