Simulation of Sliding Window Protocol

/* Simulation of Sliding Window Protocol */

// SlideServer.c : A Simple Slide Server Program Using Sliding Window Protocol

#include<stdio.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<netinet/in.h>

#include<string.h>

#include<stdlib.h>

#include<arpa/inet.h>

#define SIZE 4

int main()

{

        int sfd,lfd,len,i,j,status;

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

        struct sockaddr_in saddr,caddr;

        sfd=socket(AF_INET,SOCK_STREAM,0);

        if(sfd<0)

                perror("Error");

                bzero(&saddr,sizeof(saddr));

                saddr.sin_family=AF_INET;

                saddr.sin_addr.s_addr=htonl(INADDR_ANY);

                saddr.sin_port=htons(5465);

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

                        perror("Bind Error");

                listen(sfd,5);

                len=sizeof(&caddr);

                lfd=accept(sfd,(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+i,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(lfd,frame,sizeof(frame));

                        read(lfd,ack,20);

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

                        if(status==-1)

                                printf(" Transmission is successful. \n");

                        else

                        {

                                printf(" Received error in %d \n\n",status);

                                printf("\n\n Retransmitting Frame. ");

                                for(j=0;;)

                                {

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

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

                                        j++;

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

                                                break;

                                }

                                printf("\n");

                                frame[j]='\0';

                                len=strlen(frame);

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

                                {

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

                                        strcat(frame,temp);

                                }

                                write(lfd,frame,sizeof(frame));

                        }

                        i+=SIZE;

                }

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

                printf("Exiting\n");

                sleep(2);

                close(lfd);

                close(sfd);

}

// SlideClient.c : A Simple Slide Client Program Using Sliding Window Protocol

#include<stdio.h>

#include<string.h>

#include<stdlib.h>

#include<sys/socket.h>

#include<sys/types.h>

#include<netinet/in.h>

int main()

{

        int sfd,lfd,len,choice;

        char str[20],str1[20],err[20];

        struct sockaddr_in saddr,caddr;

        sfd=socket(AF_INET,SOCK_STREAM,0);

        if(sfd<0)

                perror("FdError");

        bzero(&saddr,sizeof(saddr));

        saddr.sin_family=AF_INET;

        saddr.sin_addr.s_addr=INADDR_ANY;

        saddr.sin_port=htons(5465);

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

        for(;;)

        {

                read(sfd,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",&choice);

                if(!choice)

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

                else

                {

                        printf("Enter the sequence no of the frame where error has occured\n");

                        scanf("%s",err);

                        write(sfd,err,sizeof(err));

                        read(sfd,str,20);

                        printf("\n\nReceived the re-transmitted frames%s\n\n",str);

                }

        }

}

OUT PUT :

SlideServer.c :

cc SlideServer.c

./a.out

Enter the text

jerusalem

Transmitting Frames=0123

Transmission is successful

Transmitting Frames=4567

Received error in 5

Retransmitting Frame=678

Transmitting Frames=8

Received error in 2

Retransmitting Frame=34

Exiting

ClientServer.c :

cc ClientServer.c

./a.out

Received=jeru0123

1.Do u want to report an error(1-Yes 0-No)0

Received=sale4567

1.Do u want to report an error(1-Yes 0-No)1

Enter the sequence no of the frame where error has occured

5

Received the re-transmitted frames=ale567

Received=m8

1.Do u want to report an error(1-Yes 0-No)1

Enter the sequence no of the frame where error has occured

2

Received the re-transmitted frames=ru23

Exiting