UNIX for Dummies Questions & Answers

// Here Data sending order goes like this.
// First Client 1 then client 2 has to send data to server for recognization.
// Then Client 2 has to start conversation then client1 , client2... 
// in this order data has to be sent
#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#define MAXSIZE 25

main()
{

	struct sockaddr_in c_addr, s1_addr;
	int sockfd, rval, addr_len;
	char buff[MAXSIZE];

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockfd == -1)
	   printf("Error while socket creation");
	
	s1_addr.sin_family = AF_INET;
	s1_addr.sin_port = htons(7035);
	s1_addr.sin_addr.s_addr = inet_addr("127.0.0.1") ;
        
	gets(buff);
	
	rval = sendto(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, sizeof(s1_addr) );
	if (rval == -1)
	{   printf("While sending problem");close(sockfd);

        } 

	while(1)
	{  //printf("from Client 1");

	

	

	addr_len = sizeof(s1_addr);
  	rval = recvfrom(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, &addr_len );
	if (rval == -1)
	{   printf("While receving  problem");close(sockfd);}
	else
	   { puts("from server received  "); 
	     puts(buff);  }

	gets(buff);
	
	rval = sendto(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, sizeof(s1_addr) );
	if (rval == -1)
	{   printf("While sending problem");close(sockfd);

        } 	
	
        } // while end 

  close(sockfd);
}

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#define MAXSIZE 25

main()
{

	struct sockaddr_in c_addr, s1_addr;
	int sockfd, rval, addr_len;
	char buff[MAXSIZE];

	sockfd = socket(AF_INET, SOCK_DGRAM, 0);
	if (sockfd == -1)
	   printf("Error while socket creation");
	
	s1_addr.sin_family = AF_INET;
	s1_addr.sin_port = htons(7035);
	s1_addr.sin_addr.s_addr = inet_addr("127.0.0.1") ;

	gets(buff);
	
	rval = sendto(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, sizeof(s1_addr) );
	if (rval == -1)
	{   printf("While sending problem");close(sockfd);

        } 

	while(1)
	{  //printf("from Client 2");

	

	gets(buff);
	
	rval = sendto(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, sizeof(s1_addr) );
	if (rval == -1)
	{   printf("While sending problem");close(sockfd);

        } 

	addr_len = sizeof(s1_addr);
  	rval = recvfrom(sockfd, buff, sizeof(buff), 0, (struct sockaddr *)&s1_addr, &addr_len );
	if (rval == -1)
	{   printf("While receving  problem");close(sockfd);}
	else
	   { puts("from server received  "); 
	     puts(buff);  }	
	
        } // while end 

  close(sockfd);
}

// Here Data sending order goes like this.
// First Client 1 then client 2 has to send data to server for recognization.
// Then Client 2 has to start conversation then client1 , client2... 
// in this order data has to be sent.


#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#define MAXSIZE 25


main()
{

    struct sockaddr_in ss_addr, c_addr,c1_addr, c2_addr ;
    int sockfd, rval, addr_len, addr_len1;
    char buff[MAXSIZE], buff1[MAXSIZE]; 

    sockfd = socket(AF_INET, SOCK_DGRAM, 0); 
    if (sockfd == -1 )
	printf("socket(logical port) creation error");  	
    //printf("bef");		 	
    ss_addr.sin_family = AF_INET;
    ss_addr.sin_port = htons(7035);
    ss_addr.sin_addr.s_addr = htonl(INADDR_ANY);	   	
     
    rval = bind(sockfd, (struct sockaddr*) &ss_addr, sizeof(ss_addr)  );
    //printf("hHHHH");
    if (rval == -1)
	{ printf( "Binding error");close(sockfd);}
    else 
 	{
              // printf("in else");
               addr_len = sizeof(c_addr);
               addr_len1 = sizeof(c1_addr);
    rval = recvfrom(sockfd, buff, sizeof(buff), 0, (struct sockaddr*)&c_addr, &addr_len );
	
    if (rval == -1)
        printf("while recving from 1st problem.");

    puts(buff);

    rval = recvfrom(sockfd, buff1, sizeof(buff1), 0, (struct sockaddr*)&c1_addr, &addr_len1 );	
    puts(buff1);

    while(1)
    {	
   
     // For Client 2
     rval = recvfrom(sockfd, buff1, sizeof(buff1), 0, (struct sockaddr*)&c1_addr, &addr_len1 );	  
    if (rval == -1)
     {   printf("while recving from 2nd problem.");close(sockfd);}

     puts(buff1);
	
    rval = sendto(sockfd, buff1, sizeof(buff1), 0, (struct sockaddr*)&c_addr, addr_len );	
 
    if (rval == -1)
        printf("while sending from server to 1st client problem.");



  // For Client 1

 

 rval = recvfrom(sockfd, buff, sizeof(buff), 0, (struct sockaddr*)&c_addr, &addr_len );	
    if (rval == -1)
    {    printf("while recving from 1st problem.");close(sockfd);}
     puts(buff);


 rval = sendto(sockfd, buff, sizeof(buff), 0, (struct sockaddr*)&c1_addr, addr_len1 );	

     
    if (rval == -1)
    {    printf("while sending from server to 2nd client problem.");close(sockfd);}

   if (rval == -1)
   { printf("breaking from loop ");close(sockfd);	
     break; 
   }  


  }  // while end 

 // printf("at end"); 
   // puts(buff);			
}
close(sockfd);	
}