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wringing out all the water

/*

login.c

Author: Tatu Ylonen <ylo@cs.hut.fi>

Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                   All rights reserved

Created: Fri Mar 24 14:51:08 1995 ylo

This file performs some of the things login(1) normally does.  We cannot
easily use something like login -p -h host -f user, because there are
several different logins around, and it is hard to determined what kind of
login the current system has.  Also, we want to be able to execute commands
on a tty.

*/

#include "includes.h"
RCSID("$Id: login.c,v 1.6 1999/09/30 05:43:33 deraadt Exp $");

#include <util.h>
#include <utmp.h>
#include "ssh.h"

/* Returns the time when the user last logged in.  Returns 0 if the 
   information is not available.  This must be called before record_login. 
   The host the user logged in from will be returned in buf. */

/* Returns the time when the user last logged in (or 0 if no previous login
   is found).  The name of the host used last time is returned in buf. */

unsigned long get_last_login_time(uid_t uid, const char *logname,
				  char *buf, unsigned int bufsize)
{
  struct lastlog ll;
  char *lastlog;
  int fd;

  lastlog = _PATH_LASTLOG;

  buf[0] = '\0';

  fd = open(lastlog, O_RDONLY);
  if (fd < 0)
    return 0;
  lseek(fd, (off_t)((long)uid * sizeof(ll)), 0);
  if (read(fd, &ll, sizeof(ll)) != sizeof(ll))
    {
      close(fd);
      return 0;
    }
  close(fd);
  if (bufsize > sizeof(ll.ll_host) + 1)
    bufsize = sizeof(ll.ll_host) + 1;
  strncpy(buf, ll.ll_host, bufsize - 1);
  buf[bufsize - 1] = 0;
  return ll.ll_time;
}

/* Records that the user has logged in.  I these parts of operating systems
   were more standardized. */

void record_login(int pid, const char *ttyname, const char *user, uid_t uid,
		  const char *host, struct sockaddr_in *addr)
{
  int fd;
  struct lastlog ll;
  char *lastlog;

  struct utmp u;
  const char *utmp, *wtmp;

  /* Construct an utmp/wtmp entry. */
  memset(&u, 0, sizeof(u));
  strncpy(u.ut_line, ttyname + 5, sizeof(u.ut_line));
  u.ut_time = time(NULL);
  strncpy(u.ut_name, user, sizeof(u.ut_name));
  strncpy(u.ut_host, host, sizeof(u.ut_host));

  /* Figure out the file names. */
  utmp = _PATH_UTMP;
  wtmp = _PATH_WTMP;
  
  login(&u);

  lastlog = _PATH_LASTLOG;

  /* Update lastlog unless actually recording a logout. */
  if (strcmp(user, "") != 0)
    {
      /* It is safer to bzero the lastlog structure first because some
	 systems might have some extra fields in it (e.g. SGI) */
      memset(&ll, 0, sizeof(ll));

      /* Update lastlog. */
      ll.ll_time = time(NULL);
      strncpy(ll.ll_line, ttyname + 5, sizeof(ll.ll_line));
      strncpy(ll.ll_host, host, sizeof(ll.ll_host));
      fd = open(lastlog, O_RDWR);
      if (fd >= 0)
	{
	  lseek(fd, (off_t)((long)uid * sizeof(ll)), 0);
	  if (write(fd, &ll, sizeof(ll)) != sizeof(ll))
	    log("Could not write %.100s: %.100s", lastlog, strerror(errno));
	  close(fd);
	}
    }
}
  
/* Records that the user has logged out. */

void record_logout(int pid, const char *ttyname)
{
  const char *line = ttyname + 5; /* /dev/ttyq8 -> ttyq8 */
  if (logout(line))
    logwtmp(line, "", "");
}