/*-------------------------------------------------------------------*/
/* client.c                                                          */
/* A client that uses sockets.                                       */
/*-------------------------------------------------------------------*/

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>

FILE *fdopen(int fildes, const char *mode);

#define BUFFER_LENGTH 100

int main(int argc, char *argv[])

/* Connect to a server whose name is argv[1] at port argv[2].
   Read a name from stdin, write that name to the server, read a 
   greeting that contains that name from the server, and write the 
   greeting to stdout. */

{
   int iRet;
   int iSocketFd;
   struct sockaddr_in sSocketAddr;
   struct hostent *psHostEntity;
   int iPort;

   if (argc != 3)
   {
      fprintf(stderr, "Usage: %s host port\n", argv[0]);
      return 1;
   }

   iRet = sscanf(argv[2], "%d", &iPort);
   if (iRet != 1)
   {
      fprintf(stderr, "Error: Port must be numeric\n");
      return 2;
   }

   /* Given the server host name, get the server host address. */

   psHostEntity = gethostbyname(argv[1]);
   if (psHostEntity == NULL)
   {
      fprintf(stderr, "Error: Unknown host\n");
      return 3;
   }

   /* Create a socket, that is, an endpoint for communication
      with the server that is identified by a file descriptor. */

   iSocketFd = socket(AF_INET, SOCK_STREAM, 0);
   if (iSocketFd == -1)
   {
      fprintf(stderr, "Error: Failed to create socket\n");
      return 4;
   }

   /* Given the server IP address, the server port, and the socket, 
      request a connection to the server through the socket. */
 
   memcpy((char*)&sSocketAddr.sin_addr, 
          psHostEntity->h_addr_list[0], 
          psHostEntity->h_length);
   sSocketAddr.sin_family = AF_INET;
   sSocketAddr.sin_port = htons((short)iPort);
   iRet = connect(iSocketFd, 
                  (struct sockaddr*)(&sSocketAddr), 
                  sizeof(sSocketAddr));
   if (iRet == -1)
   {
      perror(argv[0]);
      close(iSocketFd);
      return 5;
   }

   /* Communicate with the server via the file descriptor
      using either low-level I/O functions (write and read) or 
      standard I/O functions. */

   {
      char pcPersonName[BUFFER_LENGTH];
      char pcGreeting[BUFFER_LENGTH];
      FILE *psFile; 

      /* Wrap a FILE structure around the file descriptor to
         enable subsequent use of standard I/O functions. */

      psFile = fdopen(iSocketFd, "w+");
      if (psFile == NULL)
      {
         perror(argv[0]);
         close(iSocketFd);
         return 7;
      }

      /* Write and read data. */

      fputs("Name:  ", stdout);
      fgets(pcPersonName, BUFFER_LENGTH, stdin);
      fputs(pcPersonName, psFile);
      fflush(psFile);
      fgets(pcGreeting, BUFFER_LENGTH, psFile);
      fputs(pcGreeting, stdout);
      fclose(psFile);
   }

   return 0;
}