/* this server is used to run on Dublin.cs.unh.edu port 5678 ONLY
 * It's used to accept request from madrid.cs.unh.edu and change
 * kernel packet dropping rate and reset the number of TCP packet loss
 * to 0
 * It needs to be run by root because it will change proc files
 * It needs to be run after insert module "packet_dropper" and "change"
 * */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "server.h"
#include "tcpblockio.h"


#define BUFSIZE					10000000
#define listening_depth			2

#define SET_RATE 1
#define RECORD_LOSS 2

char	buffer[BUFSIZE];

int main( int argc, char *argv[] )
{
	int						n, len, fd, client_fd, amount, nettemp;
	struct sockaddr_in		address, client;
	pid_t pid;
	int status, command,iteration=0;
	FILE * procEntry;
	char * pathName;
	float rate;


	pathName = malloc( 256 );
	/* default to any interface. port 5678*/
	fd = openserver(5678, NULL, &address);

	/*	we are now successfully established as a server */
	/*	now accept a client connection (we'll block until one arrives) */
	len = sizeof(client);
	if( (client_fd = accept(fd, (struct sockaddr *)&client, &len)) < 0 )
		{
		perror("server accept");
		exit(EXIT_FAILURE);
		}

	/*	we are now successfully connected to a remote client */
	fprintf(stderr,
			"server: connected to client at internet address %s, port %d\n",
						inet_ntoa(client.sin_addr), ntohs(client.sin_port));

	/*	now read data messages from client then write them back */
	while( 1 )
	{
		/*	first read the size of the message blocks */
		readblock(client_fd, (char *)&nettemp, sizeof(nettemp));
		amount = ntohl(nettemp);

		/* secondly, read that amount of data */
		if( (n=readblock(client_fd, buffer, amount)) > 0 )
		{
			/* first all. Check what client needs me to do */
			sscanf( buffer, "%d", &command );
			if ( command == SET_RATE )
			{
				sscanf( buffer, "%d %f", &command, &rate );
				/* setup a directory with the rate as name */
				sprintf(pathName, "%f", rate );
				if ( mkdir( pathName, 777 ) )
				{
					fprintf(stderr, "Error making direcotry\n" );
					exit(EXIT_FAILURE );
				}
				/* change kernel drop rate via /proc file system */
				procEntry = fopen( "/proc/dropperInfo/dropper", "w" );
				if ( procEntry == NULL )
				{
				printf("Error opening: /proc/dropperInfo/dropper for writing\n" );
				exit( EXIT_FAILURE );
				}
				/* IP 192.168.2.2 */
				fprintf( procEntry, "%f %u", rate, 0x0202A8C0 );
				fclose( procEntry );

				/* reset the packet loss to 0 */
				procEntry = fopen( "/proc/dropperInfo/numDropped", "w" );
				if ( procEntry == NULL )
				{
				printf("Error opening: /proc/dropperInfo/numDropped for \n" );
				exit( EXIT_FAILURE );
				}
				fprintf( procEntry, "0" );
				fclose( procEntry );

				/* update iteration time */
				iteration = 0;

			}/* end of set rate */
			else if ( command == RECORD_LOSS )
			{
				/* cat /proc/dropperInfo/numDropped > $rate/$i */
				sprintf( pathName, "%f/%d", rate, iteration );
				if ( (pid = vfork()) < 0 )
				{
					fprintf(stderr,"error vfork()\n");
					exit(EXIT_FAILURE);
				}else if ( pid )
				{
					/*parent process waits*/
					wait(&status);
					iteration ++;
				}else
				{
					/* child process do cat */
					execlp("cat", "cat", "/proc/dropperInfo/numDropped", ">", 
							pathName, NULL);
					exit(0);
				}
					
			}
			else
			{
				fprintf( stderr, "Read bad data from client\n" );
				exit( EXIT_FAILURE );
			}
			/* server writes back the data he received as ACKnowledgement*/
			writeblock(client_fd, buffer, n);

		}/* end of if readblock OK */
		else
		{
			fprintf(stderr, "error reading from client\n");
			exit( EXIT_FAILURE );
		}
	}/* end of while */

	return 0; 	/* never reached */

}/* end of main */