/* echo-process.c
 *
 * Copyright (c) 2000 Sean Walton and Macmillan Publishers.  Use may be in
 * whole or in part in accordance to the General Public License (GPL).
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
*/

/*****************************************************************************/
/*** echo-process.c                                                        ***/
/***                                                                       ***/
/*** An echo server using processes for multiple, simultaneous connections.***/
/*****************************************************************************/

#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/socket.h>
/*#include <resolv.h>*/
#include <arpa/inet.h>

void PANIC(char* msg);
#define PANIC(msg)  { perror(msg); exit(-1); }

/*--------------------------------------------------------------------*/
/*--- Signal capture: SIGCHLD                                      ---*/
/*--------------------------------------------------------------------*/
void sig_handler(int sig)
{
  if ( sig == SIGCHLD )
    {   
      int retval;
      
      printf("\nSIG_HANDLER: Waiting for child to finish ...");
      wait(&retval);
      printf("Done.\n");
    }
}

/*--------------------------------------------------------------------*/
/*--- Child - echo servlet                                         ---*/
/*--------------------------------------------------------------------*/
void Child(void* arg)
{   
  char line[100];
  int bytes_read;
  int client = *(int *)arg;
  
  bzero(line, 100);
  
  /*    do
	{*/
  bytes_read = recv(client, line, sizeof(line), 0);
  if ( bytes_read < 0 )
    perror("Read socket");
  send(client, line, bytes_read, 0);
  
  printf("CHILD: Sent response: %s\n", line);
  /*    }
	while (strncmp(line, "bye\r", 4) != 0  ||  bytes_read < 0 );*/
  close(client);
  printf("CHILD: connection closed ...\n");
  /*exit(0);*/
}

/*--------------------------------------------------------------------*/

/*--- main - set up server and wait for connections                ---*/
/*--------------------------------------------------------------------*/
int main(void)
{   
  int sd;
  struct sigaction act;
  struct sockaddr_in addr;
  
  bzero(&act, sizeof(act));
  act.sa_handler = sig_handler;
  act.sa_flags = SA_NOCLDSTOP;
  sigaction(SIGCHLD, &act, 0);
  if ( (sd = socket(PF_INET, SOCK_STREAM, 0)) < 0 )
    PANIC("Socket");
  printf("PARENT: socket created\n");
  
  addr.sin_family = AF_INET;
  addr.sin_port = htons(9999);
  addr.sin_addr.s_addr = INADDR_ANY;
  if ( bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    PANIC("Bind");
  printf("PARENT: Socket bound\n");
  
  if ( listen(sd, 20) != 0 )
    PANIC("Listen");
  printf("PARENT: Listening ...\n");
  
  while (1)
    {   
      int client, pid, addr_size = sizeof(addr);
      
      printf("PARENT: Waiting for connection ...\n");
      client = accept(sd, (struct sockaddr*)&addr, &addr_size);
      if ( client < 0 )
	perror("Accept");
      else
	{
	  printf("PARENT: Connected: %s:%d\n", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
    	  
	  printf("PARENT: Forking ...\n");
	  if ( pid = fork() )
	    {
	      printf("PARENT: PID %d ...\n", pid); 
	      close(client);
	      printf("PARENT: Done\n");
	    }
	  else
	    {
	      printf("CHILD: PID %d ...\n", pid);
	      close(sd);
	      printf("CHILD: Processing client ...\n");
	      Child(&client);
	      printf("Child: Exiting\n");
	      exit(0);
	    }
	}
    }
  return 0;
}