Networks CAT 2

AIM – To implement sliding window protocol in noisy channels
CODE –
#include<stdio.h>
#include<string.h>
#include<stdlib.h>
struct Packet{
int data;
int seq;
int rand;
};
main(){
int win,seqmax,data;
printf("Enter the max sequence number starting from zero : ");
scanf("%d",&seqmax);
win = seqmax-1;
printf("Enter the number of packets to be sent : ");
scanf("%d",&data);
Packet sd[data];
Packet rv[win];
for(int i = 0 ; i < data ; i++){
sd[i].data = i;
sd[i].seq = i%seqmax;
}
int i,j;
int sf,sn,rn;
sf = rn = 0;
while(rn < data-win){
//Sender side
printf("Packets sent (seqnum) : ");
sn = sf;
for(i = sf ; i < win+sf ; i++){
printf("%d, ",sd[i].seq);
}
sn += win;
printf("\n");
//Network noise generation (randomize packets n lose them)
for(i = sf ; i < win+sf ; i++){
int r = (rand()%win) + sf;
rv[i-sf] = sd[r];
rv[i-sf].rand = rand()%10;
}
//Reciever Side
printf("Packets Recieved : \n");
for(i = 0 ; i < win ; i++){
printf("\t");
if(rv[i].rand > 3){
printf("%d : ",rv[i].seq);
if(rv[i].seq == sd[rn].seq){
rn++;
printf("Accepted \n");
}
else{
printf("Rejected \n");
}
}
}
printf("ACK sent with %d \n",sd[rn].seq);
//Network Noise
int k = rand()%10;
//Sender side
if(k > 3){
printf("ACK recieved for packet %d \n",sd[rn].seq);
sf = rn;
}
else{
printf("ACK lost... Timeout \n");
}
}
}
OUTPUT –
EXP - 2
AIM – To implement a TCP/IP based chat application
SERVER CODE –
//server
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
int main(int argc, char *argv[]){
int sockfd,newsockfd,clilen;
int port,n;
char buffer[256];
struct sockaddr_in serv_addr,cli_addr;
if(argc < 2){
 printf("No port provided!");
 exit(1);
}
sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd < 0){
 perror("Error during socet creation!");
 exit(2);
}
bzero((char*) &serv_addr, sizeof(serv_addr));
port = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(port);
if(bind(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 perror("Error during binding!");
 exit(3);
}
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);
if(newsockfd < 0){
 perror("Error on accept!");
 exit(4);
}
do{
 bzero(buffer,256);
 n = read(newsockfd,buffer,255);
 if(n < 0){
 perror("Error reading!");
 exit(5);
 }
 printf("Message is %s \n", buffer);
 bzero(buffer,256);
 fgets(buffer,255,stdin);
 n = write(newsockfd,buffer,255);
 if(n < 0){
 perror("Error in writing");
 exit(6);
 }
}while(1);
return 0;
}
CLIENT CODE –
//client
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
#include<netdb.h>
int main(int argc, char *argv[]){
int sockfd,port,n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
if(argc < 3){
 printf("usage %s hostname port\n",argv[0]);
 exit(1);
}
port = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0){
 perror("Error during socket creation!");
 exit(2);
}
server = gethostbyname(argv[1]);
if(server == NULL){
 printf("No such host! \n");
 exit(3);
}
bzero((char*) &serv_addr,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char*) server->h_addr,(char*)&serv_addr.sin_addr.s_addr,server->h_length);
serv_addr.sin_port = htons(port);
if(connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0){
 perror("Error connecting!");
 exit(4);
}
do{
 printf("Enter message : ");
 bzero(buffer,256);
 fgets(buffer,255,stdin);
 n = write(sockfd,buffer,strlen(buffer));
 if(n < 0){
 perror("Error in Writing");
 exit(5);
 }
 bzero(buffer,256);
 n = read(sockfd,buffer,255);
 if(n < 0){
 perror("Error Reading");
 exit(6);
 }
 printf("%s \n",buffer);
}while(1);
return 0;
}
OUTPUT –
EXP-3
AIM – To transfer a file using TCP/IP
SERVER CODE –
//server
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
int main(int argc, char *argv[]){
int sockfd,newsockfd,clilen;
int port,n;
char buffer[1024];
struct sockaddr_in serv_addr,cli_addr;
if(argc < 2){
 printf("No port provided!");
 exit(1);
}
sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd < 0){
 perror("Error during socet creation!");
 exit(2);
}
bzero((char*) &serv_addr, sizeof(serv_addr));
port = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(port);
if(bind(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 perror("Error during binding!");
 exit(3);
}
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);
if(newsockfd < 0){
 perror("Error on accept!");
 exit(4);
}
//Full setup done.... server listening
FILE *fptr;
bzero(buffer,1024);
fptr = fopen("filemsg.txt","r");
if(fptr == NULL){
 printf("File open error!");
 exit(5);
}
fscanf(fptr,"%[^\n]",&buffer);
 printf("%s \n",buffer);
 n = write(newsockfd,buffer,1023);
 if(n < 0){
 perror("Error in writing");
 exit(6);
 }
 printf("String sent : %s \n",buffer);
printf("File sent!! \n");
fclose(fptr);
close(newsockfd);
//Process ends
return 0;
}
CLIENT CODE –
// client
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
#include<netdb.h>
int main(int argc, char *argv[]){
int sockfd,port,n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[1024];
if(argc < 3){
 printf("usage %s hostname port\n",argv[0]);
 exit(1);
}
port = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0){
 perror("Error during socket creation!");
 exit(2);
}
server = gethostbyname(argv[1]);
if(server == NULL){
 printf("No such host! \n");
 exit(3);
}
bzero((char*) &serv_addr,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char*) server->h_addr,(char*)&serv_addr.sin_addr.s_addr,server->h_length);
serv_addr.sin_port = htons(port);
if(connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0){
 perror("Error connecting!");
 exit(4);
}
//Full connection done
FILE *fptr;
fptr = fopen("file1.txt","a");
if(fptr == NULL){
 printf("File error");
 exit(5);
}
bzero(buffer,1024);
 n = read(sockfd,buffer,1023);
 if(n < 0){
 perror("Error reading");
 exit(5);
 }
 fprintf(fptr,"%s",buffer);
printf("File recieved!!\n");
fclose(fptr);
//Process end
return 0;
}
OUTPUT –
EXP - 4
AIM – To implement a client server authentication using TCP/IP
SERVER CODE –
//server
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<errno.h>
#include<string.h>
int main(int argc, char *argv[]){
int sockfd,newsockfd,clilen;
int port,n;
char actuser[256];
char actpass[256];
char user[256];
char pass[256];
struct sockaddr_in serv_addr,cli_addr;
if(argc < 2){
 printf("No port provided!");
 exit(1);
}
sockfd = socket(AF_INET,SOCK_STREAM,0);
if(sockfd < 0){
 perror("Error during socket creation!");
 exit(2);
}
bzero((char*) &serv_addr, sizeof(serv_addr));
port = atoi(argv[1]);
serv_addr.sin_family = AF_INET;
serv_addr.sin_addr.s_addr = INADDR_ANY;
serv_addr.sin_port = htons(port);
if(bind(sockfd,(struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 perror("Error during binding!");
 exit(3);
}
listen(sockfd,5);
clilen = sizeof(cli_addr);
newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);
if(newsockfd < 0){
 perror("Error on accept!");
 exit(4);
}
printf("Enter actual username : ");
scanf("%s",&actuser);
printf("Enter actual password : ");
scanf("%s",&actpass);
n = write(newsockfd,"Enter username : ",17);
n = read(newsockfd,user,255);
user[strlen(user)] = '\0';
if(strcmp(user,actuser) == 10){
 n = write(newsockfd,"Enter password : ",17);
 n = read(newsockfd,pass,255);
 pass[strlen(pass)] = '\0';
 if(strcmp(pass,actpass) == 10){
 n = write(newsockfd,"Accepted!",9);
 printf("ACCEPT \n");
 }
 else{
 n = write(newsockfd,"Rejected!",9);
 printf("REJECT \n");
 close(newsockfd);
 }
}
else{
 n = write(newsockfd,"Rejected!",9);
 printf("REJECT\n");
 close(newsockfd);
}
return 0;
}
CLIENT CODE –
//client
#include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
int main(int argc, char *argv[]){
int sockfd,port,n;
struct sockaddr_in serv_addr;
struct hostent *server;
char buffer[256];
char user[256];
char pass[256];
if(argc < 3){
 printf("usage %s hostname port\n",argv[0]);
 exit(1);
}
port = atoi(argv[2]);
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if(sockfd < 0){
 perror("Error during socket creation!");
 exit(2);
}
server = gethostbyname(argv[1]);
if(server == NULL){
 printf("No such host! \n");
 exit(3);
}
bzero((char*) &serv_addr,sizeof(serv_addr));
serv_addr.sin_family = AF_INET;
bcopy((char*) server->h_addr,(char*)&serv_addr.sin_addr.s_addr,server->h_length);
serv_addr.sin_port = htons(port);
if(connect(sockfd,&serv_addr,sizeof(serv_addr)) < 0){
 perror("Error connecting!");
 exit(4);
}
bzero(buffer,256);
n = read(sockfd,buffer,255);
printf("%s",buffer);
bzero(user,256);
fgets(user,255,stdin);
n = write(sockfd,user,strlen(user));
bzero(buffer,256);
n = read(sockfd,buffer,255);
printf("%s",buffer);
bzero(pass,256);
fgets(pass,255,stdin);
n = write(sockfd,pass,strlen(pass));
bzero(buffer,256);
n = read(sockfd,buffer,255);
printf("%s\n",buffer);
return 0;
}


CYCLE SHEET 1
HAMMING
#include<stdio.h>
int main() {
	int data[7],rec[7],i,c1,c2,c3,c;
	printf("this works for message of 4bits in size \nenter message bit one by one:  ");
	scanf("%d%d%d%d",&data[0],&data[1],&data[2],&data[4]);
	data[6]=data[0]^data[2]^data[4];
	data[5]=data[0]^data[1]^data[4];
	data[3]=data[0]^data[1]^data[2];
	printf("\nthe encoded bits are given below: \n");
	for (i=0;i<7;i++) {
		printf("%d ",data[i]);
	}
	printf("\nenter the received data bits one by one: ");
	for (i=0;i<7;i++) {
		scanf("%d",&rec[i]);
	}
	c1=rec[6]^rec[4]^rec[2]^rec[0];
	c2=rec[5]^rec[4]^rec[1]^rec[0];
	c3=rec[3]^rec[2]^rec[1]^rec[0];
	c=c3*4+c2*2+c1 ;
	if(c==0) {
		printf("\ncongratulations there is no error: ");
	} else {
		printf("\nerron on the postion: %d\nthe correct message is \n",c);
		if(rec[7-c]==0)
		 			rec[7-c]=1; else
		 			rec[7-c]=0;
		for (i=0;i<7;i++) {
			printf("%d ",rec[i]);
		}
	}
return 0;
}

OSI
#include<stdio.h>
#include<string.h>
int main()
{
	char temp[20],str[20];
	printf("Enter the string");
	scanf("%s",&str);
	printf("transmitter");
	strcpy(temp,str);
	printf("Application layer: ");
	strcpy(temp,"AL");
	strcat(temp,str);
	printf("%s",temp);
	printf("Presentation Layer");
	strcpy(temp,"PL");
	strcat(temp,str);
	printf("%s\nSession Layer",temp);
	strcpy(temp,"SL");
	strcat(temp,str);
	printf("%s\ntransport layer",temp);
	strcpy(temp,"TL");
	strcat(temp,str);
	printf("%s\nNetwork layer",temp);
	strcpy(temp,"NL");
	strcat(temp,str);
	printf("%s\nData Link Layer",temp);
	strcpy(temp,"DLL");
	strcat(temp,str);
	printf("%s\nReceiver",temp);
	int i;
	printf("\nData Link Layer: ");
	for(i=0;i<strlen(str);i++)
	{printf("%c",str[i]);
	}
	printf("\nNetwork layer: ");
	for(i=4;i<strlen(str);i++)
	printf("%c",str[i]);
	printf("\nTransport layer: ");
		for(i=6;i<strlen(str);i++)
		{

	printf("%c",str[i]);}
	printf("\nSession layer: ");
	for(i=8;i<strlen(str);i++)
		{

	printf("%c",str[i]);}
	printf("\nPresentation layer: ");
		for(i=10;i<strlen(str);i++)
		{

	printf("%c",str[i]);}
	printf("\nApplication layer: ");
	for(i=12;i<strlen(str);i++)
	{printf("%c",str[i]);
	}
}

BIT STUFFING
#include<conio.h>
#include<stdio.h>
#include<string.h>
void main() {
	int i, j,count=0,nl;
	char str[100];
	printf("enter the bit string:  ");
	gets(str);
	for (i=0;i<strlen(str);i++) {
		count=0;
		for (j=i;j<=(i+5);j++) {
			if(str[j]=='1') {
				count++;
			}
		}
		if(count==6) {
			nl=strlen(str)+2;
			for (;nl>=(i+5);nl--) {
				str[nl]=str[nl-1];
			}
			str[i+5]='0';
			i=i+7;
		}
	}
	puts(str);
	getch();
}

Character Count
#include<stdio.h>
#include<string.h>
int main()
{
	int t[50],i,n;
	char s[50][50];
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%s",s[i]);
	}
	for(i=0;i<n;i++)
	t[i]=strlen(s[i]);
	printf("The transmitted data is \n");
	for(i=0;i<n;i++)
	{
		printf("%d",t[i]+1);
		printf("%s",s[i]);
	}
}

CHECKSUM
#include<stdio.h>
#include<math.h>

 int sender(int b[10],int k)
 {
 			int checksum,sum=0,i;
        	printf("\n****SENDER****\n");

			for(i=0;i<k;i++)
      		sum+=b[i];
      		printf("SUM IS: %d",sum);

    	checksum=~sum;
    	printf("\nSENDER's CHECKSUM IS:%d",checksum);
    	return checksum;
}

int receiver(int c[10],int k,int scheck)
{
			int checksum,sum=0,i;
     	printf("\n\n****RECEIVER****\n");
     	for(i=0;i<k;i++)
      		sum+=c[i];
      	printf(" RECEIVER SUM IS:%d",sum);
      	sum=sum+scheck;
      	checksum=~sum;
      	printf("\nRECEIVER's CHECKSUM IS:%d",checksum);
      		return checksum;
  }
   main()
   {
     	int a[10],i,m,scheck,rcheck;
     	printf("\nENTER SIZE OF THE STRING:");
     	scanf("%d",&m);
     	printf("\nENTER THE ELEMENTS OF THE ARRAY:");
     	for(i=0;i<m;i++)
    	scanf("%d",&a[i]);
    	scheck=sender(a,m);
    	rcheck=receiver(a,m,scheck);
    	if(rcheck==0)
      		printf("\n\nNO ERROR IN TRANSMISSION\n\n");
    	else
      		printf("\n\nERROR DETECTED");

}

CRC
#include <conio.h>
 #include <string.h>
 #include<stdio.h>
 void main()
 {
 int i,j,keylen,msglen;
 char input[100], key[30],temp[30],quot[100],rem[30],key1[30];
 printf("Enter Data: ");
 gets(input);
 printf("Enter Key: ");
 gets(key);
 keylen=strlen(key);
 msglen=strlen(input);
 strcpy(key1,key);
 for(i=0;i<keylen-1;i++)
 {
 input[msglen+i]='0';
 }
 for(i=0;i<keylen;i++)
 temp[i]=input[i];
 for(i=0;i<msglen;i++)
 {
 quot[i]=temp[0];
 if(quot[i]=='0')
 for(j=0;j<keylen;j++)
 key[j]='0';
 else
 for(j=0;j<keylen;j++)
 key[j]=key1[j];
 for(j=keylen-1;j>0;j--)
 {
 if(temp[j]==key[j])
 rem[j-1]='0';
 else
 rem[j-1]='1';
 }
 rem[keylen-1]=input[i+keylen];
 strcpy(temp,rem);
 }
 strcpy(rem,temp);
 printf("\nQuotient is ");
 for(i=0;i<msglen;i++)
 printf("%c",quot[i]);
 printf("\nRemainder is ");
 for(i=0;i<keylen-1;i++)
 printf("%c",rem[i]);
 printf("\nFinal data is: ");
 for(i=0;i<msglen;i++)
 printf("%c",input[i]);
 for(i=0;i<keylen-1;i++)
 printf("%c",rem[i]);
 getch();
 }