/*
   tcp1-serv.c: illustrates an iterative TCP server
*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <errno.h>

int main(int argc, char *argv[])
{
   int s1;			/* s1 = listen socket */
   int s2;			/* s2 = connect socket */
   struct sockaddr_in me;	/* My own Internet address */
   struct sockaddr_in myname;	/* Used to retrieve my TCP port */
   int    myname_len;

   struct sockaddr_in from;	/* Internet address from client */
   int len; 			/* length associated with `from' */

   char c;			/* Used to get data from connection */

   int x, y, z;

   if (argc == 1)
    { printf("Usage: %s port\n", argv[0]);
      exit(1);
    }

   /* ---
      Create a socket
      --- */
   s1 = socket(AF_INET, SOCK_STREAM, 0);

   /* ---
      Set up my own Internet address to bind to the socket
      --- */
   me.sin_family = AF_INET;			/* Put in the family */
   me.sin_port = htons(atoi(argv[1]));		/* Put in the port number */
   me.sin_addr.s_addr = htonl(INADDR_ANY);	/* Use wildcard address */

   /* ---
      Here goes the binding...
      --- */
   if (bind(s1, (struct sockaddr *) &me, sizeof(me) ) < 0)
    { perror("bind:");
      exit(1);
    }

   /* ---
      Just for curiousity sake, let's find out the name of the socket...
      --- */
   myname_len = sizeof(myname);
   if (getsockname(s1, (struct sockaddr *) &myname, &myname_len) == -1)
    { printf("Trouble: system did not find my socket...\n");
      exit(1);
    }
   printf("Server's listen socket is binded to:\n");
   printf("  myname.sin_family = %u (should be AF_INET = %u)\n",
		myname.sin_family, AF_INET);
   printf("  myname.sin_addr.s_addr = %u\n", myname.sin_addr.s_addr);
   printf("  myname.sin_port = %u\n", myname.sin_port);



   /* ---
      Specify the maximum number of `backlogged' connection requests
      --- */
   listen(s1, 5);

   /* ---
      After making our socket public, the server wait for connection requests
      --- */
   while (1)
    {
      /* ---
         Wait (i.e., block) until someone makes a connect call to my s1 socket
	
	 NOTE: accept RETURNS a socket descriptor similar to the socket() call
	       BUT a huge difference is accept aslo did a bind to it without
	       asking your permission
	 --- */
      printf("Ready to accept a new call.....\n");

      len = sizeof(from);
      if ( (s2 = accept(s1, (struct sockaddr *) &from, &len)) < 0)
       { perror("accept: ");
         exit(1);
       }
      printf("\n\nNew call accepted.....\n\n");
      printf("**** Information about this call:\n");

      /* ---------------------------------------
	 Print info of the listen socket
	 --------------------------------------- */
      myname_len = sizeof(myname);
      getsockname(s1, (struct sockaddr *) &myname, &myname_len);
      printf("The listen socket is:\n");
      printf("  sin_addr.s_addr = %u\n", myname.sin_addr.s_addr);
      printf("  sin_port        = %u\n\n", myname.sin_port);

      /* ---------------------------------------
	 Print info of the data socket
	 --------------------------------------- */
      myname_len = sizeof(myname);
      getsockname(s2, (struct sockaddr *) &myname, &myname_len);
      printf("The TCP connection is:\n");
      printf("========================\n");
      printf("My network address:\n");
      printf("  sin_addr.s_addr = %u\n", myname.sin_addr.s_addr);
      printf("  sin_port        = %u\n", myname.sin_port);

      /* -------------------------------------------
	 Print info of peer socket
	 ------------------------------------------- */
      myname_len = sizeof(myname);
      getpeername(s2, (struct sockaddr *) &myname, &myname_len);
      printf("The peer socket (client) network address:\n");
      printf("  sin_addr.s_addr = %u\n", myname.sin_addr.s_addr);
      printf("  sin_port        = %u\n\n", myname.sin_port);

      printf("\n\nNow reading:\n");

      while ( 1 )
      { 
         int x1, y1, z1;

         if ( read( s2, &x1, 4) <= 0 )
	    break;

         x = ntohl(x1);                // Convert to host order

         if ( read( s2, &y1, 4) <= 0 )
	    break;

         y = ntohl(y1);                // Convert to host order

	 z = x + y;
         printf("Client data: %d, %d, send sum = %d\n", x, y, z);

         z1 = htonl(z);
	 write ( s2, &z1, 4 );
      }

      close(s2);

      printf("\n\n...Done...\n\n");
    }
}