source: trunk/minix/commands/telnetd/wtmp.c@ 20

/*
 * TNET         A server program for MINIX which implements the TCP/IP
 *              suite of networking protocols.  It is based on the
 *              TCP/IP code written by Phil Karn et al, as found in
 *              his NET package for Packet Radio communications.
 *
 *              This file contains an implementation of the "server"
 *              for the TELNET protocol.  This protocol can be used to
 *              remote-login on other systems, just like a normal TTY
 *              session.
 *
 * Usage:       telnetd [-dv]
 *
 * Version:     @(#)telnetd.c   1.00    07/26/92
 *
 * Author:      Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
 *              Michael Temari, <temari@temari.ae.ge.com>
 */
#include <sys/types.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <utmp.h>
#include <time.h>
#include <stdio.h>
#include "telnetd.h"

static char PATH_UTMP[] = "/etc/utmp";
static char PATH_WTMP[] = "/usr/adm/wtmp";

_PROTOTYPE(void wtmp, (int type, int linenr, char *line, pid_t pid,
                                                                char *host));
_PROTOTYPE(void report, (char *label));

void wtmp(type, linenr, line, pid, host)
int type;                       /* type of entry */
int linenr;                     /* line number in ttytab */
char *line;                     /* tty name (only good on login) */
pid_t pid;                      /* pid of process */
char *host;                     /* name of the remote host */
{
/* Log an event into the UTMP and WTMP files. */

  struct utmp utmp;             /* UTMP/WTMP User Accounting */
  int fd;

  /* Clear the utmp record. */
  memset((void *) &utmp, 0, sizeof(utmp));

  /* Fill in utmp. */
  switch (type) {
  case LOGIN_PROCESS:
        /* A new login, fill in line and host name. */
        strncpy(utmp.ut_line, line, sizeof(utmp.ut_line));
        strncpy(utmp.ut_host, host, sizeof(utmp.ut_host));
        break;

  case DEAD_PROCESS:
        /* A logout.  Use the current utmp entry, but make sure it is a
         * user process exiting, and not getty or login giving up.
         */
        if ((fd = open(PATH_UTMP, O_RDONLY)) < 0) {
                if (errno != ENOENT) report(PATH_UTMP);
                return;
        }
        if (lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
                || read(fd, &utmp, sizeof(utmp)) == -1
        ) {
                report(PATH_UTMP);
                close(fd);
                return;
        }
        close(fd);
        if (utmp.ut_type != USER_PROCESS) return;
        strncpy(utmp.ut_name, "", sizeof(utmp.ut_name));
        break;
  }

  /* Finish new utmp entry. */
  utmp.ut_pid = pid;
  utmp.ut_type = type;
  utmp.ut_time = time((time_t *) 0);

  /* Write new entry to utmp. */
  if ((fd = open(PATH_UTMP, O_WRONLY)) < 0
        || lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
        || write(fd, &utmp, sizeof(utmp)) == -1
  ) {
        if (errno != ENOENT) report(PATH_UTMP);
  }
  if (fd != -1) close(fd);

  if (type == DEAD_PROCESS) {
        /* Add new wtmp entry. */
        if ((fd = open(PATH_WTMP, O_WRONLY | O_APPEND)) < 0
                  || write(fd, &utmp, sizeof(utmp)) == -1
        ) {
                if (errno != ENOENT) report(PATH_WTMP);
        }
        if (fd != -1) close(fd);
  }
}

void report(label)
char *label;
{
  char message[128];

  sprintf(message, "telnetd: %s: %s\r\n", strerror(errno));
  (void) write(1, message, strlen(message));
}