//-------------------------------------------------------------------
//	usenagle.cpp
//
//	Sends a stream of bytes to an echo-server using the default
//	behavior of a Linux TCP socket (i.e., the Nagle algorithm). 
//	
//	     to compile:  $ g++ usenagle.cpp -o usenagle
//	     to execute:  $ ./usenagle <target>
//
//	programmer: ALLAN CRUSE
//	written on: 01 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()
#include <arpa/inet.h>	// for inet_addr()


#define DEMO_PORT	54321


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

	//--------------------------------------------------------
	// setup hostname and network address for the remote peer 
	//--------------------------------------------------------
	char	peername[ 64 ] = { 0 }, peeraddr[ 16 ] = { 0 };
	strncpy( peername, argv[ 1 ], 63 );
	struct hostent	*pp = gethostbyname( peername );
	strcpy( peeraddr, inet_ntoa( *(in_addr*)pp->h_addr ) ); 	

	//-------------------------------------------------------
	// create a socket-address structure for the remote peer
	//------------------------------------------------------- 
	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	= inet_addr( peeraddr );

	printf( "\nDestination: %s (%s) \n", peername, peeraddr );

	//----------------------------------------------------------
	// create a socket to use for communicating with the server	
	//----------------------------------------------------------
	int	sock = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
	if ( sock < 0 ) { perror( "socket" ); exit(1); }

	//----------------------------------------------------
	// establish a connection with with the remote server
	//---------------------------------------------------- 
	if ( connect( sock, (sockaddr*)&paddr, palen ) < 0 )
		{ perror( "connect" ); exit(1); }

	//----------------------------------------------
	// prepare the message-string to be transmitted
	//----------------------------------------------
	char	msg[ 4096 ] = { 0 };
	int	k = 0;
	for (int i = 0; i < 26; i++)
		{
		for (int j = 0; j < 72; j++)
			k += sprintf( msg+k, "%c", 'a'+i );
		k += sprintf( msg+k, "\n" );
		}
	int	len = strlen( msg );

	//-------------------------------------------------------
	// write our message-string to the socket's output-queue
	//------------------------------------------------------- 
	for (int i = 0; i < len; i++) write( sock, msg+i, 1 );
	fflush( fdopen( sock, "rw" ) );

	printf( "sent %d bytes \n", len );

	//----------------------------------
	// close our socket's output-stream
	//---------------------------------- 
	shutdown( sock, SHUT_WR );
	
	//-----------------------------------------------
	// read the response from our connection-partner
	//-----------------------------------------------
	for(;;)	{
		char	buf[ 4096 ] = { 0 };
		int	rx = read( sock, buf, sizeof( buf ) );
		if ( rx == 0 ) break;	
		if ( rx < 0 ) { perror( "read" ); exit(1); }
		printf( "received %d bytes \n", rx );
		puts( buf );
		}
}