mathClient.c

/*-------------------------------------------------------------------------*
 *---									---*
 *---		mathClient.c						---*
 *---									---*
 *---	    This file defines a C program that gets file-sys commands	---*
 *---	from the user, and sends them to a server via a socket, waits	---*
 *---	for a reply, and outputs the response to the user.		---*
 *---									---*
 *---	----	----	----	----	----	----	----	----	---*
 *---									---*
 *---	Version 1.0		2018 August 9		Joseph Phillips	---*
 *---									---*
 *-------------------------------------------------------------------------*/

//	Compile with:
//	$ gcc mathServer.c -o mathServer -lpthread

//---		Header file inclusion					---//

#include	"mathClientServer.h"


//---		Definition of constants:				---//

#define	DEFAULT_HOSTNAME	"localhost.localdomain"



//---		Definition of functions:				---//

//  PURPOSE:  To ask the user for the name and the port of the server.  The
//	server name is returned in 'url' up to length 'urlLen'.  The port
//	number is returned in '*portPtr'.  No return value.
void	obtainUrlAndPort	(int		urlLen,
				 char*		url,
				 int*		portPtr
				)
{
  //  I.  Application validity check:
  if  ( (url == NULL)  ||  (portPtr == NULL) )
  {
    fprintf(stderr,"BUG: NULL ptr to obtainUrlAndPort()\n");
    exit(EXIT_FAILURE);
  }

  if   (urlLen <= 1)
  {
    fprintf(stderr,"BUG: Bad string length to obtainUrlAndPort()\n");
    exit(EXIT_FAILURE);
  }

  //  II.  Get server name and port number:
  //  II.A.  Get server name:
  printf("Machine name [%s]? ",DEFAULT_HOSTNAME);
  fgets(url,urlLen,stdin);

  char*	cPtr	= strchr(url,'\n');

  if  (cPtr != NULL)
    *cPtr = '\0';

  if  (url[0] == '\0')
    strncpy(url,DEFAULT_HOSTNAME,urlLen);

  //  II.B.  Get port numbe:
  char	buffer[BUFFER_LEN];

  printf("Port number? ");
  fgets(buffer,BUFFER_LEN,stdin);

  *portPtr = strtol(buffer,NULL,10);

  //  III.  Finished:
}


//  PURPOSE:  To attempt to connect to the server named 'url' at port 'port'.
//	Returns file-descriptor of socket if successful, or '-1' otherwise.
int	attemptToConnectToServer	(const char*	url,
					 int		port
					)
{
  //  I.  Application validity check:
  if  (url == NULL)
  {
    fprintf(stderr,"BUG: NULL ptr to attemptToConnectToServer()\n");
    exit(EXIT_FAILURE);
  }


  //  II.  Attempt to connect to server:
  //  II.A.  Create a socket:
  int socketDescriptor = socket(AF_INET, // AF_INET domain
				SOCK_STREAM, // Reliable TCP
				0);

  //  II.B.  Ask DNS about 'url':
  struct addrinfo* hostPtr;
  int status = getaddrinfo(url,NULL,NULL,&hostPtr);

  if (status != 0)
  {
    fprintf(stderr,gai_strerror(status));
    return(-1);
  }

  //  II.C.  Attempt to connect to server:
  struct sockaddr_in server;
  // Clear server datastruct
  memset(&server, 0, sizeof(server));

  // Use TCP/IP
  server.sin_family = AF_INET;

  // Tell port # in proper network byte order
  server.sin_port = htons(port);

  // Copy connectivity info from info on server ("hostPtr")
  server.sin_addr.s_addr =
	((struct sockaddr_in*)hostPtr->ai_addr)->sin_addr.s_addr;

  status = connect(socketDescriptor,(struct sockaddr*)&server,sizeof(server));

  if  (status < 0)
  {
    fprintf(stderr,"Could not connect %s:%d\n",url,port);
    return(-1);
  }

  //  III.  Finished:
  return(socketDescriptor);
}


//  PURPOSE:  To ask the user for a file number, and to return that number.
//	No parameters.
int		getFileNumber	()
{
  //  I.  Application validity check:

  //  II.  Get number:
  char	buffer[BUFFER_LEN];
  int	choice;

  do
  {
    printf("  File number (%d-%d)? ",MIN_FILE_NUM,MAX_FILE_NUM);
    fgets(buffer,BUFFER_LEN,stdin);
    choice	= strtol(buffer,NULL,10);
  }
  while ( (choice < MIN_FILE_NUM)  ||  (choice > MAX_FILE_NUM) );

  //  III.  Finished:
  return(choice);
}


//  PURPOSE:  To 
const char*   	getText		()
{
  //  I.  Application validity check:

  //  II.  :
  static
  char	buffer[BUFFER_LEN-2*sizeof(int)];

  printf("  Expression? ");
  fgets(buffer,BUFFER_LEN-2*sizeof(int),stdin);
  
  for(int i = 0; i < BUFFER_LEN; i++){
	  if(buffer[i] == '\n'){
		  buffer[i] = '\0';
	  }
  }

  //  III.  Finished:
  return(buffer);
}


//  PURPOSE:  To do the work of the application.  Gets letter from user, sends
//	it to server over file-descriptor 'fd', and prints returned text.
//	No return value.
void		communicateWithServer
				(int		fd
				)
{
  //  I.  Application validity check:

  //  II.  Do work of application:
  //  II.A.  Get letter from user:
  char	buffer[BUFFER_LEN+1];
  int	shouldContinue	= 1;

  while  (shouldContinue)
  {
    int	choice;

    do
    {
      printf
	("What would you like to do:\n"
	 "(1) List files\n"
	 "(2) Read a math file\n"
	 "(3) Write a math file\n"
	 "(4) Calculate a math file\n"
	 "(5) Delete a math file\n"
	 "(0) Quit\n"
	 "Your choice? "
	);
      fgets(buffer,BUFFER_LEN,stdin);
      choice = strtol(buffer,NULL,10);
    }
    while  ( (choice < 0)  ||  (choice > 5) );

    switch  (choice)
    {
    case 0 :
      shouldContinue	= 0;
      snprintf(buffer,BUFFER_LEN,"%c",QUIT_CMD_CHAR);
      break;

    case 1 :
      snprintf(buffer,BUFFER_LEN,"%c",DIR_CMD_CHAR);
      break;

    case 2 :
      snprintf(buffer,BUFFER_LEN,"%c %d",READ_CMD_CHAR,getFileNumber());
      break;

    case 3 :
      snprintf(buffer,BUFFER_LEN,"%c %d \"%s\"",
	       WRITE_CMD_CHAR,getFileNumber(),getText()
	      );
      break;

    case 4 :
      snprintf(buffer,BUFFER_LEN,"%c %d",CALC_CMD_CHAR,getFileNumber());
      break;

    case 5 :
      snprintf(buffer,BUFFER_LEN,"%c %d",DELETE_CMD_CHAR,getFileNumber());
      break;

    }
    
    for(int i=0; i < sizeof(buffer)/sizeof(char); i++){
		printf("%d %c\n", (int)buffer[i], buffer[i]);
	}

printf("Sending \"%s\"\n",buffer);
    write(fd,buffer,strlen(buffer)+1);
    read (fd,buffer,BUFFER_LEN);

    printf("%s\n",buffer);
  }

  //  III.  Finished:
}


//  PURPOSE:  To do the work of the client.  Ignores command line parameters.
//	Returns 'EXIT_SUCCESS' to OS on success or 'EXIT_FAILURE' otherwise.
int	main	()
{
  char		url[BUFFER_LEN];
  int		port;
  int		fd;

  obtainUrlAndPort(BUFFER_LEN,url,&port);
  fd	= attemptToConnectToServer(url,port);

  if  (fd < 0)
    exit(EXIT_FAILURE);

  communicateWithServer(fd);
  close(fd);
  return(EXIT_SUCCESS);
}