//-------------------------------------------------------------------
//	sixlinks.cpp
//
//	This TCP client establishes six connections with our server,
//	for checking the server's abiity to handle multiple clients.
//
//	    to compile:  $ g++ sixlinks.cpp -o sixlinks
//	    to execute:  $ ./sixlings <target>
//
//	programmer: ALLAN CRUSE
//	written on: 09 MAR 2009
//-------------------------------------------------------------------

#include <netdb.h>	// for gethostbyname()
#include <stdio.h>	// for printf(), perror() 
#include <stdlib.h>	// for exit() 
#include <unistd.h>	// for read(), write(), close() 
#include <string.h>	// for strncpy(), strlen()


#define DEMO_PORT	54321
#define NUM_LINKS	6


int main( int argc, char **argv )
{
	//-----------------------------------------------
	// check for the mandatory command-line argument 
	//-----------------------------------------------
	if ( argc == 1 )
		{
		fprintf( stderr, "must specify server\n" );
		exit(1);
		}

	//-------------------------------------------------
	// get the server's hostname from the command-line
	//-------------------------------------------------
	char	peername[ 64 ] = { 0 };
	strncpy( peername, argv[ 1 ], 63 );
	
	//-------------------------------------
	// obtain the IP-address of the server
	//-------------------------------------
	struct hostent	*pp = gethostbyname( peername );
	if ( !pp ) { herror( "gethostbyname" ); exit(1); }

	//--------------------------------------------
	// construct a socket-address for this server
	//--------------------------------------------
	struct sockaddr_in	paddr = { 0 };
	socklen_t		palen = sizeof( paddr );
	paddr.sin_family	= AF_INET;
	paddr.sin_port		= htons( DEMO_PORT );
	paddr.sin_addr.s_addr	= *(int32_t*)pp->h_addr;

	//-----------------------------------------------------------
	// create an array of sockets for connecting with the server
	//-----------------------------------------------------------
	int	sock[ NUM_LINKS ];
	for (int i = 0; i < NUM_LINKS; i++)
		{
		sock[ i ] = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP ); 
		if ( sock[ i ] < 0 ) { perror( "socket" ); exit(1); }
		}

	//----------------------------------------------------
	// establish six separate connections with the server 
	//----------------------------------------------------		
	for (int i = 0; i < NUM_LINKS; i++)
		{
		if ( connect( sock[ i ], (sockaddr*)&paddr, palen ) < 0 )
			{ perror( "connect" ); exit(1); }
		}

	//-----------------------------------------------------------
	// send a message to the server on each of these connections 
	//-----------------------------------------------------------
	char	msg[ 40 ] = "Never the twain shall meet\n";		
	
	for (int i = 0; i < NUM_LINKS; i++)
		{		
		int	tx = write( sock[ i ], msg, strlen( msg ) );
		if ( tx < 0 ) { perror( "write" ); exit(1); }

		fflush( fdopen( sock[ i ], "rw" ) );
		if ( shutdown( sock[ i ], SHUT_WR ) < 0 ) perror( "shutdown" );
		puts( msg );	
		}

	//---------------------------------------------------------
	// receive the server's reply on each of these connections 
	//---------------------------------------------------------
	for (int i = 0; i < NUM_LINKS; i++)
		{
		char	buf[ 40 ] = { 0 };
	
		int	rx = read( sock[ i ], buf, strlen( msg ) );
		if ( rx < 0 ) { perror( "read" ); exit(1); }
		puts( buf );
		}

	//---------------------------------------------
	// close down each of these socket-connections
	//---------------------------------------------
	for (int i = 0; i < NUM_LINKS; i++) close( sock[ i ] );
}