NETWORK LAB-SLIDING WINDOW PROTOCOL-SELECTIVE REPEAT N ARQ

               SELECTIVE REPEAT AND ARQ

SENDER SIDE:-

#include<stdio.h>

#include<stdlib.h>

#include<fcntl.h>

#include<sys/types.h>

#include<sys/socket.h>

#include<netinet/in.h>

#include<string.h>

int converttoframes(char *n,char data[100][100],int power)

{ FILE *fp;

int k=0,i;

fp=fopen(n,"r");

while(!feof(fp))

{ data[k][0]=k%power+48;

for(i=1;i<9;i++)

data[k][i]=fgetc(fp);

data[k++][i]='\0'; } return (k-1); }

int main(int argc,char **argv)

{ int len,bits,frames,errbit,once;

int sws,lfs,lar;

int sockfd;

int n,l=0,i,j=0,choice=0,k,pre=0;

int flag=-1,count,re=0,ch=0;

struct sockaddr_in servaddr,cliaddr;

char data[100][100],ack[1];

char buff[100][100],buff1[10];

char name[50];

int *recvd,power=1,gla=0;

sockfd=socket(AF_INET,SOCK_STREAM,0);

if(sockfd<0)

perror("Cannot create a socket");

bzero(&servaddr,sizeof(servaddr));

bzero(&buff[0],sizeof(buff[0]));

bzero(&buff1,sizeof(buff1));

servaddr.sin_family=AF_INET;

servaddr.sin_addr.s_addr=inet_addr(argv[1]);

servaddr.sin_port=htons(7995);

connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));

printf("Enter the window size:-");

scanf("%d",&sws);

printf("Enter the file name:-");

scanf("%s",name);

for(i=0;i<sws;i++)

power*=2;

frames=converttoframes(name,data,power);

recvd=(int *)malloc(sizeof(int)*sws);

recvd[-1]=1;

for(i=0;i<sws;i++)

recvd[i]=-1;

while(choice!=6)

{ flag=-1;

count=0;

for(i=0;i<sws;i++)

recvd[i]=-1;

printf("\n\t~~Choose cases~~\n1.Normal\t2.Ack Lost\t3.Data Lost\n4.Delayed Ack\t5.Wrong Data\t6.Exit\tChoice : ");

scanf("%d",&choice);

//printf("\n");

switch(choice)

{ case 1:

for(k=0;k<frames;k++)

{ j=0;

strcpy(buff[k],data[k]);

for(i=1;i<strlen(buff[k]);i++)

{ if(buff[k][i]=='1')

j++; }

if(j%2==0)

buff[k][i++]='0';

else

buff[k][i++]='1';

buff[k][i]='\0';

send(sockfd,buff[k],strlen(buff[k]),0);

recv(sockfd,ack,1,0);

lfs=k%power;

printf("\nLast frame sent:-%d",lfs);

lar=atoi(ack);

recvd[lar]=lar;

if(count==sws-1)

{ printf("\nACK:-");

printf("%d",lar); }

else if(count==sws)

count=0;

count++; }

break;

case 2: lar=0;

for(k=0;k<frames+1;k++)

{ if(k==frames && recvd[count-1]!=-1)

break;

once=0;

j=0;

strcpy(buff[k],data[k]);

for(i=1;i<strlen(buff[k]);i++)

{ if(buff[k][i]=='1')

j++; }

if(j%2==0)

buff[k][i++]='0';

else

buff[k][i++]='1';

buff[k][i]='\0';

if(count<sws)

{ if(flag!=-1)

{ wait(10);

printf("\nTIME OUT!!!"); }

send(sockfd,buff[k],strlen(buff[k]),0);

recv(sockfd,ack,1,0);

lfs=k%power;

printf("\nLast frame sent:-%d",lfs);

if(count==sws-1)

{ printf("\nAck lost?-1/0:-");

scanf("%d",&once); }

if(once==1)

recvd[count]=-1;

else

{ lar=atoi(ack);

recvd[count]=lar; }

if(once!=1 && count==sws-1)

{ if(ack[0]!='n')

{ printf("\nACK:-");

printf("%d",lar); }

else

{ printf("\nNAK:-");

printf("%d",lfs); } }

count++;

if(flag!=-1)

{ k=flag-1;

flag=-1;

count=0; } }

else

{ for(i=0;i<sws;i++)

{ if(recvd[i]==-1)

{ flag=k;

if(k>sws)

k=i-1+sws;

else

k=i-1;

count=count-1; } }

if(flag==-1)

{ for(i=0;i<sws;i++)

recvd[i]=-1;

count=0;

k=k-1; } }

bzero(&buff[k+1],sizeof(buff[k+1])); }

//bzero(&recvd,sizeof(recvd));

break;

case 3:

lar=0;

count=0;

for(k=0;k<frames+1;k++)

{

j=0;

if(k==frames && recvd[count-1]!=-1 && recvd[count-2]!=-1)

break;

strcpy(buff[k],data[k]);

for(i=1;i<strlen(buff[k]);i++)

{

if(buff[k][i]=='1')

j++;

}

if(j%2==0)

buff[k][i++]='0';

else

buff[k][i++]='1';

buff[k][i]='\0';

if(count<sws)

{

send(sockfd,buff[k],strlen(buff[k]),0);

recv(sockfd,ack,1,0);

lfs=k%power;

printf("\nLast frame sent:-%d",lfs);

if(ack[0]!='n')

{

lar=atoi(ack);

recvd[count]=lar;

}

else

recvd[count]=-1;

if(ack[0]!='n' && count==sws-1 && recvd[gla]!=-1)

{

printf("\nACK:-");

if(lar<frames-1)

printf("%d",lar+1);

else

printf("%d",lar);

}

else if(count==sws-1)

{

printf("\nNAK:-");

if(recvd[gla]==-1)

printf("%d",lfs-1);

else if(recvd[count]==-1)

printf("%d",lfs);

}

count++;

if(flag!=-1)

{

k=flag-1;

flag=-1;

count=0;

gla=0;

}

}

else

{

for(i=0;i<sws;i++)

{

if(recvd[i]==-1)

{

flag=k;

if(k>sws)

k=i-1+sws;

else

k=i-1;

if(i==0)

gla=1;

count=count-1;

}

}

if(flag==-1)

{ for(i=0;i<sws;i++)

recvd[i]=-1;

count=0;

k=k-1; } }

bzero(&buff[k+1],sizeof(buff[k+1])); }

//bzero(&recvd,sizeof(recvd));

break;

case 4:

lar=0;

for(k=0;k<frames+1;k++)

{ j=0;

once=0;

if(k==frames && recvd[count-1]!=-1)

break;

strcpy(buff[k],data[k]);

for(i=1;i<strlen(buff[k]);i++)

{ if(buff[k][i]=='1')

j++; }

if(j%2==0)

buff[k][i++]='0';

else

buff[k][i++]='1';

buff[k][i]='\0';

if(count<sws)

{ if(flag!=-1)

{ wait(10);

printf("\nTIME OUT!!!"); }

send(sockfd,buff[k],strlen(buff[k]),0);

recv(sockfd,ack,1,0);

if(count==sws-1)

{printf("\nAck delayed?-1/0:-");

scanf("%d",&once); }

if(once==1)

recvd[count]=-1;

else

{ lar=atoi(ack);

recvd[count]=lar; }

if(once!=1 && count==sws-1)

{ if(ack[0]!='n')

{ printf("\nACK : ");

printf("%d",lar); }

else

{ printf("\nNAK:-");

printf("%d",lfs); } }

count++;

if(flag!=-1)

{

k=flag-1;

flag=-1;

count=0; } }

else

{ for(i=0;i<sws;i++)

{ if(recvd[i]==-1)

{ flag=k;

if(k>sws)

k=i-1+sws;

else

k=i-1;

count=count-1; } }

if(flag==-1)

{ for(i=0;i<sws;i++)

recvd[i]=-1;

count=0;

k=k-1; } }

bzero(&buff[k+1],sizeof(buff[k+1])); }

//bzero(&recvd,sizeof(recvd));

break;

case 5:

count=0;

lar=0;

flag=0;

for(k=0;k<frames;k++)

{ j=0;

strcpy(buff1,data[k]);

for(i=1;i<strlen(buff1);i++)

{ if(buff1[i]=='1')

j++; }

if(j%2==0)

buff1[i++]='0';

else

buff1[i++]='1';

buff1[i]='\0';

printf("\nWanna introduce Error?-yes/no:-");

scanf("%d",&ch);

if(ch==1)

{ printf("\nIn which position to introduce error? ");

scanf("%d",&errbit);

if(buff1[errbit]=='1')

buff1[errbit]='0';

else

buff1[errbit]='1';

flag=buff1[0]-48;

if(flag<0)

flag+=48; }

send(sockfd,buff1,strlen(buff1),0);

recv(sockfd,ack,1,0);

lfs=k%power;

if(count==sws-1)

{ if(ack[0]!='n' && flag==0 && lar!=0)

{ printf("\nACK:-");

printf("%d",lar); }

else

{ printf("\nNAK:-");

printf("%d",flag);

flag=0; }

count=-1; }

else

if(ack[0]!='n')

flag=1;

count++;

lar=ack[0]-48;

if(lar<0)

lar+=48;

bzero(&buff1,sizeof(buff1)); }

l=0;

break;

case 6:

buff[0][1]='!';

send(sockfd,buff[0],1,0);

break; } }

shutdown(sockfd,SHUT_RDWR);

return 0; }

RECEIVER SIDE:-

#include<stdio.h>

#include<stdlib.h>

#include<fcntl.h>

#include<unistd.h>

#include<sys/types.h>

#include<sys/socket.h>

#include<netinet/in.h>

#include<string.h>

int main(int argc,char **argv)

{ int sockfd,newfd,len,count=0;

struct sockaddr_in servaddr,cliaddr;

int i,j=0,n,once=0;

int *recvd;

char s[10],ack[1];

int rws,lfr=0,mult;

sockfd=socket(AF_INET,SOCK_STREAM,0);

if(sockfd<0)

perror("Cannot create socket");

bzero(&servaddr,sizeof(servaddr));

bzero(&s,sizeof(s));

servaddr.sin_family=AF_INET;

servaddr.sin_port=htons(7995);

servaddr.sin_addr.s_addr=inet_addr(argv[1]);

if(bind(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0)

perror("Bind error");

listen(sockfd,2);

len=sizeof(&cliaddr);

newfd=accept(sockfd,(struct sockaddr*)&cliaddr,&len);

bzero(&s,sizeof(s));

printf("Enter the window size:-");

scanf("%d",&rws);

mult=rws*2;

recvd=(int *)malloc(sizeof(int)*mult);

printf("Expecting frame:-%d",lfr);

recv(newfd,s,sizeof(s),0);

while(strcmp(s,"!"))

{ printf("\n");

j=0;

printf("\nData:-%s",s);

recvd[lfr]=lfr;

for(i=1;i<strlen(s);i++)

{ if(s[i]=='1')

j=j+1; }

if(j%2==0)

ack[0]=lfr+48;

else

ack[0]='n';

printf("\nData lost?-1/0:-");

scanf("%d",&once);

if(once==1)

ack[0]='n';

send(newfd,ack,1,0);

bzero(&s,sizeof(s));

recv(newfd,s,sizeof(s),0);

lfr=s[0]-48;

if(lfr<0)

lfr+=48;

printf("Expecting frame:-%d",lfr); }

shutdown(sockfd,SHUT_RDWR);

shutdown(newfd,SHUT_RDWR);

return 0; }

INPUT FILE:-

11110000111100000000111100001111