/* fingerd.c -- Stripped finger daemon (shows logins and idle time). $Id: fingerd.c,v 0.1 1997/05/21 18:48:54 eagle Exp $ Copyright 1997 by Russ Allbery Based on code by Larry Schwimmer This is a stripped version of fingerd, designed to do nothing other than show the list of logins and idle times for a given user (the so-called short format). It was motivated by the need for other people to determine my idle time without having a local login, but under a situation where I would prefer people not be able to get full finger information or a full list of users. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /*************************************************************************** * Includes and #defines ***************************************************************************/ #ifdef UTMPX #define HAVE_UTMPX_H #endif #include /* isspace(), isprint() */ #include /* getpwnam(), struct passwd */ #include /* fgets(), stdin, printf() */ #include /* exit() */ #include /* strncmp(), memcpy() */ #include /* stat(), S_IWGRP, S_IWOTH */ #include /* time_t */ #include /* time(), strftime() */ #ifdef HAVE_UTMPX_H #include /* getutxent(), setutxent(), etc. */ #else #include /* getutent(), setutnet(), etc. */ #endif #ifndef MIN #define MIN(a, b) (((a) < (b)) ? (a) : (b)) #endif /*************************************************************************** * Display utmp information ***************************************************************************/ /* Create a string that indicates when a user logged in. This is tricky. We want to just give day of the weak unless they logged in more than a week ago, in which case we want to give the month and day, unless they logged in more than a year ago, in which case we want to give month and year. */ void build_when (char *buffer, int bufsize, struct tm *login_ptr, time_t current) { struct tm login; struct tm *now; /* Make a local copy, since we're going to call localtime() again. */ memcpy (&login, login_ptr, sizeof (struct tm)); /* Get the current time. */ now = localtime (¤t); /* Put the appropriate string in the buffer. */ if ((now->tm_year == login.tm_year && now->tm_yday - login.tm_yday < 7) || (now->tm_year - login.tm_year == 1 && (now->tm_yday + 365 + ((login.tm_year % 400 == 0) ? 1 : 0) + ((login.tm_year % 100 != 0 && (login.tm_year % 4 == 0)) ? 1 : 0) - login.tm_yday < 7))) { /* Less than a week ago. */ strftime (buffer, bufsize, "%a %H:%M", &login); } else if (now->tm_year == login.tm_year || (now->tm_year - login.tm_year == 1 && now->tm_mon < login.tm_mon)) { /* Less than a year ago. */ strftime (buffer, bufsize, "%e %h %y", &login); } else { /* More than a year ago. */ strftime (buffer, bufsize, " %h %Y", &login); } } /* Print out the header line for user login information. */ void print_banner () { printf ("Login Name TTY Idle When Where"); printf ("\r\n"); } /* We're being passed in a username which corresponds to some user on the system. Step through each line in utmp/utmpx looking for any entries matching that user which are active processes, and for each one print out the login information. */ void print_logins (char *name) { int banner = 0; #ifdef HAVE_UTMPX_H struct utmpx *ut; #else struct utmp *ut; #endif time_t now = time (NULL); /* Reset the getut(x)ent pointers and loop through all utmp(x) entries. */ #ifdef HAVE_UTMPX_H setutxent (); while (ut = getutxent ()) #else setutent (); while (ut = getutent ()) #endif { struct stat tty_status; struct tm *login_time; struct passwd *user_info; char tty[38] = "/dev/"; char frombuf[23]; char idlebuf[6] = " "; char linebuf[9]; char namebuf[21] = ""; char userbuf[9]; char whenbuf[10]; int mesg = 0; time_t idle; if (ut->ut_type != USER_PROCESS) continue; if (strncmp (name, ut->ut_user, sizeof (ut->ut_user))) continue; /* Create a string representing the login time. */ #ifdef HAVE_UTMPX_H login_time = localtime (&ut->ut_tv.tv_sec); #else login_time = localtime (&ut->ut_time); #endif build_when (whenbuf, sizeof (whenbuf), login_time, now); /* Usernames could be more than 8 characters, but only print 8. */ strncpy (userbuf, name, 8); userbuf[8] = '\0'; #ifdef HAVE_UTMPX_H /* Correct for munged utmpx files. */ if (ut->ut_syslen < 0) ut->ut_syslen = 22; #endif /* Build the contents of the "where" field. */ if (ut->ut_host[0] && isprint (ut->ut_host[0])) { #ifdef HAVE_UTMP_X strncpy (frombuf, ut->ut_host, MIN (ut->ut_syslen, 22)); frombuf[MIN (ut->ut_syslen, 22)] = '\0'; #else strncpy (frombuf, ut->ut_host, MIN (sizeof (ut->ut_host), 22)); frombuf[MIN (sizeof (ut->ut_host), 22)] = '\0'; #endif } else frombuf[0] = '\0'; /* Figure out the current idle time. */ strncat (tty, ut->ut_line, sizeof (tty) - 6); tty[37] = '\0'; if (stat (tty, &tty_status) == 0) { mesg = (tty_status.st_mode & (S_IWGRP | S_IWOTH)); idle = now - tty_status.st_atime; /* Convert the idle time to a string. */ idle /= 60; if (idle >= 60) { if (idle >= 1440) { /* Over one day of idle time, convert to days. */ idle /= 1440; if (idle <= 9999) sprintf (idlebuf, "%4dd", idle); else sprintf (idlebuf, "years"); } else { /* Idle time measured in hours. Show minues if < 10h. */ if (idle >= 600) sprintf (idlebuf, " %2dh", idle / 60); else sprintf (idlebuf, "%2d:%02d", idle / 60, idle % 60); } } else if (idle > 0) { /* Idle time measured in minutes (don't show if seconds). */ sprintf (idlebuf, " %2d", idle); } } /* Build the full name field. */ user_info = getpwnam (name); if (user_info != NULL) { strncpy (namebuf, user_info->pw_gecos, 20); namebuf[20] = '\0'; } /* Build the name of the tty. Remap pts/ttyXY to ttyXY on HP-UX. */ if (ut->ut_line[0] == 'p' && ut->ut_line[4] == 't') strncpy (linebuf, ut->ut_line + 4, 8); else strncpy (linebuf, ut->ut_line, 8); linebuf[8] = '\0'; /* Actually print out the line. */ if (!banner) { banner = 1; print_banner (); } printf ("%-8s %-21s%c%-8s %5s %9s %-16s\r\n", userbuf, namebuf, mesg ? ' ' : '*', linebuf, idlebuf, whenbuf, frombuf); } /* If we never printed anything out, say something uninformative. */ if (!banner) printf ("Sorry, no information available for this user.\r\n"); } /*************************************************************************** * Main routine ***************************************************************************/ /* Read a single line in from stdin, stripping off options if they exist (since we completely ignore whether the client wants wide format or not), and then call print_logins with the username there. If they're trying to do finger forwarding or null queries, tell them to go away. */ int main (void) { char buffer[128]; char *name, *end; /* Read the name in from stdin. */ name = fgets (buffer, sizeof (buffer), stdin); if (name == NULL || *name == '\0' || *name == '\r') { printf ("Sorry, list of on-line users not available.\r\n"); exit (0); } /* Skip past an initial /W and white space, if present (ignoring it). */ if (name[0] == '/' && name[1] == 'W') { name += 2; while (*name == ' ' || *name == '\t') name++; } /* Find the end of the username and null-terminate. */ end = name; while (*end && !isspace (*end)) end++; *end = '\0'; /* Verify that they actually gave us a username. If so, display the results, otherwise bail with an uninformative error message. */ if (end == name || getpwnam (name) == NULL) printf ("Sorry, no information available for this user.\r\n"); else print_logins (name); }