/*
 * argus - tell when people login and when they logout
 *
 * original fido (logins only) by don hopkins (a2deh@mit-mc.arpa)
 * argus by andrew scott beals (bandy@lll-crg.arpa)
 * wakeup detection by paul rubin (phr@ernie.berkeley.edu)
 *
 */

#include <stdio.h>
#include <utmp.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <ctype.h>

#ifndef DEBUG
#define NAPTIME 1800
#else
#define NAPTIME 5
#endif

#define	TRUE	1
#define	FALSE	0

char	*calloc(), *getlogin();

struct utmp utmp;
char  **Argv;
int   *loggedin, *wasloggedin;

int     Argc;

main (argc, argv)
int	argc;
char  **argv; {
    int     pid;
    char    error[128];

#ifndef DEBUG
    if ((pid = fork ()) == -1) {
	sprintf(error, "%s: can't fork", *argv);
	perror (error);
	exit (-1);
    }
    if (pid)			/* parent boogies out */
	exit (0);
    signal(SIGTTOU, SIG_IGN);
#endif
    Argc = argc;
    GetNames(argv);
    loggedin = (int *) calloc(Argc, sizeof (int));
    wasloggedin = (int *) calloc(Argc, sizeof (int));
    if (argc == 1) {
	printf ("\r\nusage: %s user ...\r\n", *Argv);
	exit (0);
    }
    prowl ();
    for (;;) {
	if(getlogin() == NULL) exit(0);
	sleep (10);
	prowl ();
    }
}

/* GetNames - copy argv array to Argv and hide original */
GetNames(argv)
char **argv;
{
  int i, n = 0;
  char *buf;

  for (i = 0; i < Argc; i++)
    n += strlen(argv[i]) + 1;

  Argv = (char **) calloc(Argc, sizeof (char *));
  buf = (char *) malloc(n+1);
  for (i = 0; i < Argc; i++) {
    strcpy(buf, argv[i]);
    Argv[i] = buf;
    buf += strlen(argv[i]) + 1;
    while (*argv[i] != '\0')
      *(argv[i]++) = '\0';
  }
}

prowl () {
    static char  ut[] = { "/etc/utmp" };
    register	j;
    register    FILE * fi;

    if ((fi = fopen (ut, "r")) == NULL) {
	printf ("\r\n\007[%s: cannot open utmp! Yargh! Bye!]\r\n", *Argv);
	exit (-1);
    }
    for(j=1;j<Argc;j++) {
	wasloggedin[j] = loggedin[j];
	loggedin[j] = 0;
    }
    while (fread ((char *) & utmp, sizeof (utmp), 1, fi) == 1) {
	if (utmp.ut_name[0] == '\0')
	    continue;
	sniff ();
    }
    /* not logged in */
    for(j = 1;j < Argc;j++) {
	if((wasloggedin[j] != 0) && (loggedin[j] == 0)) {
	    printf("\r\n\7[%s: there goes %.8s!]\r\n", *Argv, Argv[j]);
	}
    }
    fclose (fi);
}

sniff ()
{
  register int    i;
  
  for (i = 1; i < Argc; i++) {
    if (smellslike (Argv[i], utmp.ut_name, sizeof (utmp.ut_name))==TRUE) {
      int barked = 0;
      loggedin[i] = 1;
      if (wasloggedin[i] == 0) {
	bark ("Here is %s!");
	barked++;
      }
      if (isupper(*Argv[i])) {
	static char buf[100];
	struct stat sbuf;
	sprintf(buf, "/dev/", buf);
	strncat(buf, utmp.ut_line, sizeof (utmp.ut_line));
	if (stat(buf, &sbuf) >= 0) {
#ifdef DEBUG
	  printf("stat %s succeeded...\n", buf);
	  loggedin[i] = sbuf.st_mtime;
#else
	  loggedin[i] = sbuf.st_atime;
#endif
	  if (loggedin[i] - wasloggedin[i] > NAPTIME && !barked)
	    bark("%s woke up!");
	}
      return;
      }
    }
  }
}

smellslike(sample, person, len)
     char *sample, *person;
     int len;
{
  int i;
  char c1, c2;
  for (i = 0; i < len; i++) {
    if (person[i] == '\0' && sample[i] == '\0')
      return TRUE;
    c1 = isupper(person[i]) ? tolower(person[i]) : person[i];
    c2 = isupper(sample[i]) ? tolower(sample[i]) : sample[i];
    if (c1 != c2)
      return FALSE;
  }
  return TRUE;
}
    
bark (format)
     char *format;
{
  char buf[100], buf2[200];
  printf("\r\n\7[%s: ", *Argv);
  if(*utmp.ut_host)
    sprintf(buf, "%.8s@%s", utmp.ut_name, utmp.ut_host);
  else
    sprintf(buf, "%.8s", utmp.ut_name);
  sprintf(buf2, format, buf);
  printf("%s]\n", buf2);
}