commands/telnetd/wtmp.c

   1 /*
   2  * TNET         A server program for MINIX which implements the TCP/IP
   3  *              suite of networking protocols.  It is based on the
   4  *              TCP/IP code written by Phil Karn et al, as found in
   5  *              his NET package for Packet Radio communications.
   6  *
   7  *              This file contains an implementation of the "server"
   8  *              for the TELNET protocol.  This protocol can be used to
   9  *              remote-login on other systems, just like a normal TTY
  10  *              session.
  11  *
  12  * Usage:       telnetd [-dv]
  13  *
  14  * Version:     @(#)telnetd.c   1.00    07/26/92
  15  *
  16  * Author:      Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  17  *              Michael Temari, <temari@temari.ae.ge.com>
  18  */
  19 #include <sys/types.h>
  20 #include <fcntl.h>
  21 #include <errno.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <utmp.h>
  26 #include <time.h>
  27 #include <stdio.h>
  28 #include "telnetd.h"
  29
  30 static char PATH_UTMP[] = "/etc/utmp";
  31 static char PATH_WTMP[] = "/usr/adm/wtmp";
  32
  33 _PROTOTYPE(void wtmp, (int type, int linenr, char *line, pid_t pid,
  34                                                                 char *host));
  35 _PROTOTYPE(void report, (char *label));
  36
  37 void wtmp(type, linenr, line, pid, host)
  38 int type;                       /* type of entry */
  39 int linenr;                     /* line number in ttytab */
  40 char *line;                     /* tty name (only good on login) */
  41 pid_t pid;                      /* pid of process */
  42 char *host;                     /* name of the remote host */
  43 {
  44 /* Log an event into the UTMP and WTMP files. */
  45
  46   struct utmp utmp;             /* UTMP/WTMP User Accounting */
  47   int fd;
  48
  49   /* Clear the utmp record. */
  50   memset((void *) &utmp, 0, sizeof(utmp));
  51
  52   /* Fill in utmp. */
  53   switch (type) {
  54   case LOGIN_PROCESS:
  55         /* A new login, fill in line and host name. */
  56         strncpy(utmp.ut_line, line, sizeof(utmp.ut_line));
  57         strncpy(utmp.ut_host, host, sizeof(utmp.ut_host));
  58         break;
  59
  60   case DEAD_PROCESS:
  61         /* A logout.  Use the current utmp entry, but make sure it is a
  62          * user process exiting, and not getty or login giving up.
  63          */
  64         if ((fd = open(PATH_UTMP, O_RDONLY)) < 0) {
  65                 if (errno != ENOENT) report(PATH_UTMP);
  66                 return;
  67         }
  68         if (lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
  69                 || read(fd, &utmp, sizeof(utmp)) == -1
  70         ) {
  71                 report(PATH_UTMP);
  72                 close(fd);
  73                 return;
  74         }
  75         close(fd);
  76         if (utmp.ut_type != USER_PROCESS) return;
  77         strncpy(utmp.ut_name, "", sizeof(utmp.ut_name));
  78         break;
  79   }
  80
  81   /* Finish new utmp entry. */
  82   utmp.ut_pid = pid;
  83   utmp.ut_type = type;
  84   utmp.ut_time = time((time_t *) 0);
  85
  86   /* Write new entry to utmp. */
  87   if ((fd = open(PATH_UTMP, O_WRONLY)) < 0
  88         || lseek(fd, (off_t) (linenr+1) * sizeof(utmp), SEEK_SET) == -1
  89         || write(fd, &utmp, sizeof(utmp)) == -1
  90   ) {
  91         if (errno != ENOENT) report(PATH_UTMP);
  92   }
  93   if (fd != -1) close(fd);
  94
  95   if (type == DEAD_PROCESS) {
  96         /* Add new wtmp entry. */
  97         if ((fd = open(PATH_WTMP, O_WRONLY | O_APPEND)) < 0
  98                   || write(fd, &utmp, sizeof(utmp)) == -1
  99         ) {
 100                 if (errno != ENOENT) report(PATH_WTMP);
 101         }
 102         if (fd != -1) close(fd);
 103   }
 104 }
 105
 106 void report(label)
 107 char *label;
 108 {
 109   char message[128];
 110
 111   sprintf(message, "telnetd: %s: %s\r\n", strerror(errno));
 112   (void) write(1, message, strlen(message));
 113 }