Stuff

#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <sys/select.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#define BUFFER_S 1024

void serve(int sd);

main( int argc, char **argv )
{
      int PORT;
      int lsd;                       // Listening socket
      struct sockaddr_in sin;
      int sin_size=sizeof(sin);
      int sd;                        // Socket gia tis nees sindeseis
      
      int enable=1;                  // &setsockopt                                    
      char answr;                    // y or n
      int flag=0;

      //Dimiourgia socket
      if ( (lsd=socket(AF_INET, SOCK_STREAM, 0)) < 0 ) {
            fprintf(stderr, "%s: cannot create listening socket: ",argv[0]);
            perror(0);
            exit(1);
      }

    
      PORT=atoi(argv[1]);
      printf("* * * Welcome to the SERVER * * *\n");
      printf("Socket will bind to port %d\n",PORT);
      
      sin.sin_family         = AF_INET; //Internet domain. Kathe socket tautopoieitai apo to IP kai to port.
      sin.sin_port           = htons(PORT); //Kathorizei to port number. To htons einai 'host to network short', morfi apodekti apo ola ta systimata.
      sin.sin_addr.s_addr = htonl(INADDR_ANY);
      
      if ( bind(lsd, &sin, sin_size) < 0 ) {		//dinete dieu8insi sto socket
            fprintf(stderr, "%s: cannot bind listening socket: ",argv[0]);
            perror(0);
            exit(1);
      }
                         
      if ( listen(lsd, 5) < 0 ) {		//Me to listen orizoume mikos ouras anamonis.
            fprintf(stderr, "%s: cannot listen on socket: ",argv[0]);
            perror(0);
            exit(1);
      }
  
      while ( 1 ) {
      printf("\n\nServer ready for connections!\n");
            if ( (sd=accept(lsd, &sin, &sin_size)) < 0 )		//dimiourgia neou socket kai enosi me ton client
                   exit(errno);
      do{
           flag=0;
           answr=' ';
           printf("Do you wish to accept the chat invitation ?(y/n)\n");
           scanf("%c",&answr);
           switch (answr)
           {
           case 'y':
                             write(sd,"accept",strlen("accept"));
                             serve(sd);
                             break;
           case 'Y':
                             write(sd,"accept",strlen("accept"));
                             serve(sd);
                             break;
           case 'n':
                             write(sd,"quit",sizeof("quit"));
                             break;
           case 'N':
                             write(sd,"quit",sizeof("quit"));
                             break;
           default: printf("answer with y or n %c\n",answr);
                             getchar();
                             flag=1;
                             break;
           }
           }     while (flag==1);
           shutdown(sd, 2);
           close(sd);
      }
}

void serve(int sd)
{
	FILE *fs;
	int r;

	char buffer[BUFFER_S];
	memset(buffer,0,sizeof(buffer));  //Katharismos tou buffer.
	
	if ((fs=fopen("server.dat","w"))==NULL)
		{
			printf("could not open and write to file\n");
			exit(1);
		}
	
	while(read(sd,&buffer,sizeof(buffer))>0) 		//diavazei osa byte xorei o buffer
			fprintf(fs,"%s",buffer);	
	printf("\n%s\n",buffer);
	fclose(fs);
						
}