Protocol - 3 (Simplex Protocol For Noisy Channel)

[ SENDER SIDE ]

#include<stdio.h>
#include<fcntl.h>
#include<string.h>
typedef struct
{
int seqno,ackno;
char data[50];
}frame;
int getAck()
{
int pid,ack=0;
pid=open("pipe2",O_RDONLY);
if(pid>0)
{
read(pid,&ack,sizeof(ack));
unlink("pipe2");
}
close(pid);
return ack;
}
int start_timer(int ack)
{
int i;
printf("\ntimer starts");
for(i=0;i<10;i++)
{
printf("\n%d",i+1);
sleep(1);
if(ack==getAck())
{
return 0;
}
}
return 1;
}
void from_network_layer(char buffer[])
{
printf("Enter data : ");
scanf("%s",buffer);
}
void to_physical_layer(frame *f)
{
int pid;
system(">pipe1");
pid=open("pipe1",O_WRONLY);
if(pid>0)
{
write(pid,f,sizeof(frame));
}
close(pid);
}
void main()
{
int n,i;
char buffer[50];
frame f;
printf("Enter how many data want to send : ");
scanf("%d",&n);
for(i=1;i<=n;i++)
{
from_network_layer(buffer);
strcpy(f.data,buffer);
f.seqno=i;
do
{
printf("\n\t...data send...\n");
to_physical_layer(&f);
}while(start_timer(i));
}
}

[ RECEIVER SIDE ]

#include<stdio.h>
#include<fcntl.h>
#include<string.h>
typedef struct
{
int seqno,ackno;
char data[50];
}frame;
int getAck()
{
int pid,ack=0;
pid=open("pipe2",O_RDONLY);
if(pid>0)
{
read(pid,&ack,sizeof(ack));
unlink("pipe2");
}
close(pid);
return ack;
}
int start_timer(int ack)
{
int i;
printf("\ntimer starts");
for(i=0;i<10;i++)
{
printf("\n%d",i+1);
sleep(1);
if(ack==getAck())
{
return 0;
}
}
return 1;
}
void to_network_layer(char buffer[])
{
printf("\nYour data : %s",buffer);
}
void from_physical_layer(frame *f)
{
int pid;
pid=open("pipe1",O_RDONLY);
printf("\nfile operation : %d\n",pid);
if(pid>0)
{
read(pid,f,sizeof(frame));
unlink("pipe1");
}
close(pid);
}
void send_ack(int seqno)
{
int pid;
system(">pipe2");
pid=open("pipe2",O_WRONLY);
if(pid>0)
{
write(pid,&seqno,sizeof(seqno));
}
close(pid);
}
void main()
{
int n,i;
char buffer[50];
frame f;
from_physical_layer(&f);
strcpy(buffer,f.data);
to_network_layer(buffer);
send_ack(f.seqno);
}