//----------------------------------------------------------------
//	txalpha.cpp
//
//
//	     compile using:  $ g++ txalpha.cpp -o txalpha
//	     execute using:  $ ./txalpha <server-hostname>
//
//	programmer: ALLAN CRUSE
//	written on: 13 APR 2008
//----------------------------------------------------------------

#include <sys/socket.h>	// for socket()
#include <netinet/in.h>	// for PF_INET, SOCK_STREAM, IPPROTO_TCP
#include <netdb.h>	// for gethostbyname()
#include <stdio.h>	// for printf(), perror()
#include <string.h>	// for bzero(), bcopy()
#include <unistd.h>	// for read(), write(), close()
#include <fcntl.h>	// for open()
#include <sys/mman.h>	// for mmap()

#define DEMO_PORT 9734	

char filename[] = "alphabet.dat";

int main( int argc, char *argv[] )
{
	//------------------------------------------------
	// Get host information for the designated server
	//------------------------------------------------
	if ( argc == 1 )
		{
		fprintf( stderr, "must specify hostname\n" );
		return	-1;
		}

	struct hostent	*hp = gethostbyname( argv[1] );
	if ( !hp )
		{
		fprintf( stderr, "%s: unknown host\n", argv[1] );
		return	-1;
		}

	//------------------------------------
	// create the socket on which to send
	//------------------------------------
	int	sock = socket( PF_INET, SOCK_STREAM, IPPROTO_TCP );
	if ( sock < 0 )
		{
		perror( "opening stream socket" );
		return	-1;
		}
	printf( "\nsock=%d \n", sock );

	//-------------------------
	// construct a socket name
	//-------------------------
	struct sockaddr_in	name;
	socklen_t		nlen = sizeof name;
	bzero( &name, nlen );
	bcopy( hp->h_addr, &name.sin_addr, hp->h_length );
	name.sin_family = AF_INET;
	name.sin_port = htons( DEMO_PORT );

	//----------------------------------------
	// Establish a connection with the server
	//----------------------------------------
	if ( connect( sock, (sockaddr *)&name, nlen ) < 0 )
		{
		fprintf( stderr, "cannot connect\n" );
		return	-1;
		}
	printf( "connect succeeded\n" );

	//---------------------
	// open the image-file
	//---------------------
	int	fd = open( filename, O_RDONLY );
	if ( fd < 0 ) { perror( filename ); return -1; }
	int	size = lseek( fd, 0, SEEK_END );
	int	prot = PROT_READ;
	int	flag = MAP_PRIVATE;
	void	*img = mmap( NULL, size, prot, flag, fd, 0 );
	if ( img == MAP_FAILED ) { perror( "mmap" ); return -1; }

	//-------------------------------
	// write the image to the socket 
	//-------------------------------
	int	nbytes = write( sock, img, size );
	printf( "transmitted %d bytes \n", nbytes );

	//------------------------------------------------
	// close the connection to the server-application
	//------------------------------------------------ 
	close( sock );
	printf( "\n" );
}