NPM- 5th ex

5th ex:-

PROGRAM:

SERVER:

#include<stdio.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<netinet/in.h>

#include<arpa/inet.h>

#define SIZE 4

main()

{

int sd,ld,len,i,j,st;

char str[20],frame[20],temp[20],ack[20];

struct sockaddr_in saddr,caddr;

sd=socket(AF_INET,SOCK_STREAM,0);

if(sd<0)

perror("error");

bzero(&saddr,sizeof(saddr));

saddr.sin_family=AF_INET;

saddr.sin_addr.s_addr=htonl(INADDR_ANY);

saddr.sin_port=htons(6616);

if(bind(sd,(struct sockaddr *)&saddr,sizeof(saddr))<0)

perror("bind error");

listen(sd,5);

len=sizeof(&caddr);

ld=accept(sd,(struct sockaddr *)&caddr,&len);

printf("enter the text\n");

scanf("%s",str);

i=0;

while(i<strlen(str))

{

memset(frame,0,20);

strncpy(frame,str+1,SIZE);

printf("transmitting frames");

len=strlen(frame);

for(j=0;j<len;j++)

{

printf("%d",i+j);

sprintf(temp,"%d",i+j);

strcat(frame,temp);

}

printf("\n");

write(ld,frame,sizeof(frame));

read(ld,ack,20);

sscanf(ack,"%d",&st);

if(st==-1)

printf("transmission is successful\n");

{

printf("received error in %d\n\n",st);

printf("\nretransmitting frame");

for(j=0;;)

{

frame[j]=str[j+st];

j++;

printf("%d",j+st);

if((j+st)%4==0)

break;

}

printf("\n");

frame[j]='\0';

len=strlen(frame);

for(j=0;j<len;j++)

{

sprintf(temp,"%d",j+st);

strcat(frame,temp);

}

write(ld,frame,sizeof(frame));

}

i+=SIZE;

}

write(ld,"exit",sizeof("exit"));

printf("\nexiting\n");

sleep(2);

close(ld);

close(sd);

}

CLIENT:

#include<stdio.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<netinet/in.h>

main()

{

int sd,len,op;

char str[20],err[20];

struct sockaddr_in saddr;

sd=socket(AF_INET,SOCK_STREAM,0);

if(sd<0)

perror("ERROR");

bzero(&saddr,sizeof(saddr));

saddr.sin_family=AF_INET;

inet_pton(AF_INET,"172.16.6.4",&saddr.sin_addr);

saddr.sin_port=htons(6616);

connect(sd,(struct sockaddr *)&saddr,sizeof(saddr));

for(;;)

{

read(sd,str,20);

if(!strcmp(str,"exit"))

{

printf("exiting\n");

break;

}

printf("\n\nreceived%s\n\n1.do u want to report an error(1-yes,0-no)",str);

scanf("%d",op);

if(op)

{

printf("enter the sequence no. of frame when error has occured\n");

scanf("%s",err);

write(sd,err,sizeof(err));

read(sd,str,20);

printf("\n\nreceived the retransmitted frames %s\n\n",str);

}

else

write(sd,"-1",sizeof("-1"));

}

}

OUTPUT:

SERVER:

[it86091@vecit ~]$ cc prog5b.c

[it86091@vecit ~]$ ./a.out

enter the text

hello

transmitting frames0123

received error in 3

retransmitting frame4

transmitting frames4567

received error in 1

retransmitting frame234

exiting

CLIENT:

[it86091@vecit ~]$ cc prog5a.c

[it86091@vecit ~]$ ./a.out

receivedello0123

1.do u want to report an error(1-yes,0-no)1

enter the sequence no. of frame when error has occured

3

received the retransmitted frames l3

receivedello4567

1.do u want to report an error(1-yes,0-no)

enter the sequence no. of frame when error has occured

1

received the retransmitted frames ell123

exiting