Expected Dates for NP Lab Practical Examinations

Expected dates for NP-Lab practical external examinations  on or after 25th oct'12.
NOTE : Dates r tentative ,u must confirm the dates.
 

Imp Q's for MID-2 Examination for Final B.Tech , Sub : NP

Expected q's

1)    a) Write a sample to discuss lack of flow control in UDP.

b) Discuss about recvfrm(),sendto(),read() functions.

2)  a) Discuss types of resource records.

      b) Discuss about resolver functions.

3)  Explain with diagrams for the following I/O multiplexing  

      models

              i) Blocking.

               ii) Non-blocking.

              iii) Signal driven.

4) Explain the role of resolver with neat diagram that depict the management of application, resolver and name server.

5) a) discuss about functionalities of select and poll functions

     b) discuss about resolver options RSE_USE_INIT6.

NP Lab 6,7 and 8 programs for SSNCET Final Yr Students

/*
must update ur records uptodate and submit to internal examination :

internal dates :
CSE-A  :    8-10-2012
CSE-B  :    6-10-2012
*/

W6

/* UDP client and server application to reverse the given input sentence */

/* client program */

# include "unp.h"

/* UDP ECHO Client: dg_cli function*/

 void dg_cli(FILE *fp,int sockfd,const  SA* pservaddr,socklen_t servlen)

 {

          int  n;

          char sendline[MAXLINE], recvline[MAXLINE+1];

          while ( Fgets(sendline,MAXLINE,fp)!=NULL)

          {

              sendto(sockfd, sendline, strlen(sendline), 0, pservaddr,servlen);

              n= Recvfrom(sockfd,recvline, MAXLINE,0,NULL,NULL);

              recvline[n]=0;

             Fputs(recvline, stdout);

         }

}

      

/*   UDP client main function: */

         int main(int argc, char **argv)

         {

 

             int sockfd;

             struct   sockaddr_in   servaddr;

             if(argc!=2)

                    err_quit("usage : udpcli <Ipaddress>");

            bzero(&servaddr, sizeof(servaddr));

           servaddr.sin_family= AF_INET;

           servaddr.sin_port = htons(SERV_PORT);

           Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

           sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

           dg_cli(stdin, sockfd, (SA*) &servaddr, sizeof(servaddr));

           exit(0);

      }

/* compiling */

$ cc udp_simple_client.c wrapsock.c –o udpreverseclient

/* execution */

$ ./ udpreverseclient

hai

Iah

/* UDP server program */

# include "unp.h"

/* UDP echo server dg_echo function: */

     void dg_echo(int sockfd,SA*pcliaddr,socklen_t clilen)

     {

            int n,i,j,swp;

            socklen_t len;

            char mesg[MAXLINE];

            for(;;){

                len=clilen;

                n=Recvfrom(sockfd,mesg,MAXLINE,0,pcliaddr,&len);

          printf("From Client : %s reversing ..",mesg);  

          for(i=0,j=n-1;i<n/2;i++,j--)

          {

          swp=mesg[i];

          mesg[i]=mesg[j];

          mesg[j]=swp;

          }

             Sendto(sockfd,mesg,n,0,pcliaddr,len);

                   }

     }

         

/*UDP echo server main function:*/

     #include"unp.h"

     int main(int argc,char **argv[])

     {

         int sockfd;

         struct sockaddr_in servaddr,cliaddr;

         sockfd=socket(AF_INET,SOCK_DGRAM,0);

            bzero(&servaddr,sizeof(servaddr));

            servaddr.sin_family=AF_INET;

            servaddr.sin_addr.s_addr=htonl(INADDR_ANY);

            servaddr.sin_port=htons(SERV_PORT);

         Bind(sockfd,(SA*)&servaddr,sizeof(servaddr));

         dg_echo(sockfd,(SA*)&cliaddr,sizeof(cliaddr));

     }

/* compiling */

$ cc udp_simple_server.c wrapsock.c –o udpreverseserver

/* output */

$./ udpreverseserver

Rev hai

W7

/* UDP client and server application to transfer a text file*/

/*client program */

# include "unp.h"

/* UDP ECHO Client: dg_cli function*/

 void dg_cli(FILE *fp,int sockfd,const  SA* pservaddr,socklen_t servlen)

 {

          int  n;

          char sendline[MAXLINE], recvline[MAXLINE+1];

          while ( Fgets(sendline,MAXLINE,fp)!=NULL)

          {

              sendto(sockfd, sendline, strlen(sendline), 0, pservaddr,servlen);

              n= Recvfrom(sockfd,recvline, MAXLINE,0,NULL,NULL);

              recvline[n]=0;

             Fputs(recvline, stdout);

         }

}

      

/*   UDP client main function: */

         int main(int argc, char **argv)

         {

 

             int sockfd;

             struct   sockaddr_in   servaddr;

             if(argc!=2)

                    err_quit("usage : udpcli <Ipaddress>");

            bzero(&servaddr, sizeof(servaddr));

           servaddr.sin_family= AF_INET;

           servaddr.sin_port = htons(SERV_PORT);

           Inet_pton(AF_INET, argv[1], &servaddr.sin_addr);

           sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

           dg_cli(stdin, sockfd, (SA*) &servaddr, sizeof(servaddr));

           exit(0);

      }

/* compiling */

$ cc udp_simple_file_client.c wrapsock.c –o udpfileclient

/* execution */

$ ./ udpfileclient

File name :myfile

Hello worild……

-------------

/* server program */

# include "unp.h"

/* UDP echo server dg_echo function: */

     void dg_echo(int sockfd,SA*pcliaddr,socklen_t clilen)

     {

          FILE*f;  

            int n,i=0,ch;

            socklen_t len;

            char mesg[MAXLINE];

            for(;;){

                len=clilen;

                n=Recvfrom(sockfd,mesg,MAXLINE,0,pcliaddr,&len);

          printf(" sending data.");   

          f=fopen("myfile","r");

          while((ch=getc(f))!=-1)

          mesg[i++]=ch;

          mesg[i]=0; //init null

             Sendto(sockfd,mesg,i,0,pcliaddr,len);

                   }

     }

         

/*UDP echo server main function:*/

     #include"unp.h"

     int main(int argc,char **argv[])

     {

         int sockfd;

         struct sockaddr_in servaddr,cliaddr;

         sockfd=socket(AF_INET,SOCK_DGRAM,0);

            bzero(&servaddr,sizeof(servaddr));

            servaddr.sin_family=AF_INET;

            servaddr.sin_addr.s_addr=htonl(INADDR_ANY);

            servaddr.sin_port=htons(SERV_PORT);

         Bind(sockfd,(SA*)&servaddr,sizeof(servaddr));

         dg_echo(sockfd,(SA*)&cliaddr,sizeof(cliaddr));

     }

$ cc udp_simple_file_server.c wrapsock.c –o udpfileserver

/* execution */

$ ./ udpfileserver

Wating for client request :

W8

Design TCP concurrent server to convert a given text into upper case using multiplexing system call select()

/* TCP CLIENT with SELECT */

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <fcntl.h>

#define MAXBUFFER 1024

void sendstring(int , char *);

int main( int C, char *V[] )

{

int sd,fd;

char c;

struct sockaddr_in serveraddress;

char text[100];

int i=0;

sd = socket( AF_INET, SOCK_STREAM, 0 );

if( sd < 0 ) {

perror( "socket" );

exit( 1 );

}

if (V[1] == NULL ) {

printf ("PL specfiy the server's IP Address \n");

exit(0);

}

if (V[2] == NULL ) {

printf ("PL specify the server's Port No \n");

exit(0);

}

memset( &serveraddress, 0, sizeof(serveraddress) );

serveraddress.sin_family = AF_INET;

serveraddress.sin_port = htons(atoi(V[2]));//PORT NO

serveraddress.sin_addr.s_addr = inet_addr(V[1]);//ADDRESS

if (connect(sd,(struct sockaddr*)&serveraddress,

sizeof(serveraddress))<0)

{

printf("Cannot Connect to server");

exit(1);

}

printf("enter sentence to end enter #");

while(1)

{

c=getchar();

if(c=='#')

break;

text[i++]=c;

}

text[i]='\0';

sendstring(sd,text);

close(sd);

return 0;

}

/***********************************************************

* FUNCTION NAME:sendstring

* DESCRIPTION: sends a string over the socket .

* NOTES : No Error Checking is done .

* RETURNS :void

**********************************************************/

void sendstring(

int sd, /*Socket Descriptor*/

char *fname) /*Array Containing the string */

/***********************************************************/

{ int n , byteswritten=0 , written ;

char buffer[MAXBUFFER];

strcpy(buffer , fname);

n=strlen(buffer);

while (byteswritten<n)

{

written=write(sd , buffer+byteswritten,(n-byteswritten));

byteswritten+=written;

}

printf("String : %s sent to server \n",buffer);

}

/***********************************************************/

/*

Compiling and running Client.

root@localhost week7and8]# ./tcpclient 127.0.0.1 13153

enter sentence to end enter #abcd#

String : abcd sent to server

*/

/*TCP SERVER_SELECT*/

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <sys/select.h>

#include <sys/time.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <fcntl.h>

#define MAXLINE 100

#define SERV_PORT 13153

int main(int argc, char **argv)

{

int k, i, maxi, maxfd, listenfd, connfd, sockfd;

int nready, client[FD_SETSIZE];

ssize_t n;

fd_set rset, allset;

char line[MAXLINE],buf[100];

socklen_t clilen;

struct sockaddr_in cliaddr, servaddr;

listenfd = socket(AF_INET, SOCK_STREAM, 0);

if (listenfd < 0 )

{

perror("socket" );

exit(1);

}

bzero(&servaddr, sizeof(servaddr));

servaddr.sin_family = AF_INET;

servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

servaddr.sin_port = htons(SERV_PORT);

bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)); G. Narayanamma Institute of Technology & Science.(for Women)– CSE Dept 6 Day Workshop on “Network Programming and Simulators” 5th – 10th July 2010 - 30 -

listen(listenfd,5);

maxfd = listenfd; /* initialize */

maxi = -1; /* index into client[] array */

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

client[i] = -1; /* -1 indicates available entry */

FD_ZERO(&allset);

FD_SET(listenfd, &allset);

/* end fig01 */

/* include fig02 */

for ( ; ; ) {

printf("Server:I am waiting-----Start of Main Loop\n");

rset = allset; /* structure assignment */

nready = select(maxfd+1, &rset, NULL, NULL, NULL);

if (FD_ISSET(listenfd, &rset)) {

/* new client connection */

clilen = sizeof(cliaddr);

connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &clilen);

#ifdef NOTDEF

printf("new client: %s, port %d\n",inet_ntop(AF_INET,

&cliaddr.sin_addr, buf, NULL),ntohs(cliaddr.sin_port));

#endif

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

if (client[i] < 0) {

client[i] = connfd; /* save descriptor */

break;

}

if (i == FD_SETSIZE)

{

printf("too many clients");

exit(0);

}

FD_SET(connfd, &allset);

/* add new descriptor to set */

if (connfd > maxfd)

maxfd = connfd;

/* for select */

if (i > maxi)

maxi = i;

/* max index in client[] array */

if (--nready <= 0)

continue;

/* no more readable descriptors */

}

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

/* check all clients for data */

if ( (sockfd = client[i]) < 0)

continue;

if (FD_ISSET(sockfd, &rset)) {

if ( (n = read(sockfd, line, MAXLINE)) == 0) {

/*4connection closed by client */

close(sockfd);

FD_CLR(sockfd, &allset);

client[i] = -1;

} else

{

printf("\n output at server\n");

for(k=0;line[k]!='\0';k++)

printf("%c",toupper(line[k]));

write(sockfd, line, n);

}

if (--nready <= 0)

break;

/* no more readable descriptors */

}

}

}

}

/*

EXECUTION AND RESULTS

Compiling and running server.

root@localhost week7and8]# cc tcpservselect01.c

[root@localhost week7and8]# mv a.out tcpservselect1

[root@localhost week7and8]# ./tcpservselect

 [root@localhost week7and8]# ./tcpservselect1

Server:I am waiting-----Start of Main Loop

Server:I am waiting-----Start of Main Loop

output at server

A B C DServer:I am waiting-----Start of Main Loop

output at server

A B C DServer:I am waiting-----Start of Main Loop

Server:I am waiting-----Start of Main Loop

*/